Quasar pair, a special subclass of galaxy pair, is valuable in the investigation of quasar interaction, co-evolution, merger, and clustering, as well as the formation and evolution of galaxies and supermassive black holes. However, quasar pairs at kpc-scale are rare in the universe. The scarcity of available samples hindered the deeper exploration and statistics of these objects. In this work, we apply an astrometric method to systematically search for quasar candidates within a transverse distance of 100 kpc to known quasars in the Million Quasar Catalog. These candidates are ${\it Gaia}$ sources with zero proper motion and zero parallax, which are the kinematic characteristics of extragalactic sources. Visual inspection of the sample was performed to remove the contamination of dense stellar fields and nearby galaxies. A total of 4,062 quasar pair candidates were isolated, with the median member separation, ${\it Gaia}$ G-band magnitude, and redshift of 8.81$^{\prime\prime}$, 20.49, and 1.59, respectively. Our catalog was compared with three major candidate quasar pair catalogs and identified 3,964 new quasar pair candidates previously uncataloged in the three catalogs. Extensive spectroscopic follow-up campaigns are being carried out to validate their astrophysical nature. Several interesting quasar pair candidates are highlighted and discussed. We also briefly discussed several techniques for improving the success rate of quasar pair selection.

Mass loss through stellar winds governs the evolution of stars on the asymptotic giant branch (AGB). In the case of carbon-rich AGB stars, the wind is believed to be driven by radiation pressure on amorphous carbon (amC) dust forming in the atmosphere. The choice of dust optical data will have a significant impact on atmosphere and wind models of AGB stars. We compare two commonly used optical data sets of amC and investigate how the wind characteristics and photometric properties resulting from dynamical models of carbon-rich AGB stars are influenced by the micro-physical properties of dust grains. We computed two extensive grids of carbon star atmosphere and wind models with the DARWIN 1D radiation-hydrodynamical code. Each of the two grids uses a different amC optical data set. The stellar parameters of the models were varied to cover a wide range of possible combinations. A posteriori radiative transfer calculations were performed for a sub-set of the models, resulting in photometric fluxes and colours. We find small, but systematic differences in the predicted mass-loss rates for the two grids. The grain sizes and photometric properties are affected by the different dust optical data sets. Higher absorption efficiency leads to the formation of a greater number of grains, which are smaller. Models that are obscured by dust exhibit differences in terms of the covered colour range compared to observations, depending on the dust optical data used. An important motivation for this study was to investigate how strongly the predicted mass-loss rates depend on the choice of dust optical data, as these mass-loss values are more frequently used in stellar evolution models. Based on the current results, we conclude that mass-loss rates may typically differ by about a factor of two for DARWIN models of C-type AGB stars for commonly used dust optical data sets.

We introduce a new 1D stellar spectral synthesis Python code called \stardis. \stardis\ is a modular, open-source radiative transfer code that is capable of spectral synthesis from near-UV to IR for FGK stars. We describe the structure, inputs, features, underlying physics, and assumptions of \stardis\ as well as the radiative transfer scheme implemented. To validate our code, we show spectral comparisons between \stardis\ and \textsc{korg} with the same input atmospheric structure models, and also compare qualitatively to \textsc{phoenix} for solar models. We find that \stardis\ generally agrees well with \textsc{korg} for solar models on the few percent level or better, that the codes can diverge in the ultraviolet, with more extreme differences in cooler stars. \stardis\ can be found at \href{https://github.com/tardis-sn/stardis}{https://github.com/tardis-sn/stardis}, and documentation can be found at \href{https://tardis-sn.github.io/stardis/}{https://tardis-sn.github.io/stardis/}.

We present WI2easy, a Mathematica package for high-precision analysis of warm inflation (WI) dynamics, enabling efficient computation of both background evolution and curvature perturbations. Designed with a user-friendly interface, the tool supports a broad spectrum of inflaton potentials--including large-field, small-field, and hybrid models--and accommodates arbitrary dissipation coefficients dependent on temperature, field amplitude, or both, encompassing canonical forms prevalent in WI studies. Users can define custom models through intuitive commands, generating full dynamical trajectories and perturbation spectra in a streamlined workflow. This facilitates rapid confrontation of theoretical predictions with observational constraints, empowering systematic exploration of WI parameter spaces. WI2easy bridges the gap between theoretical models and observational cosmology, offering a robust, adaptable framework for next-generation inflationary analyses.

We consider, in the context of axion-inflation, the \textit{Pure Natural Inflation} (PNI) model coupled with an SU(2) gauge sector via a Chern-Simons term. As the axion rolls down its potential, it dissipates energy in the gauge sector thus sourcing fluctuations of scalar and tensor degrees of freedom therein. Gauge field fluctuations will, in turn, feed primordial gravitational waves as well as curvature perturbations. Remarkably, we can use upcoming cosmological probes to test this mechanism across a vast range of scales, from the CMB to laser interferometers. Due to their flat plateau at large field values, we find that PNI potentials fare better vis-\'{a}-vis CMB observations than the conventional sinusoidal potential of chromo-natural inflation (CNI). We show that, even when the dynamics begin in the weak backreaction regime, the rolling of the axion leads to a build-up of the gauge-quanta production, invariably triggering the strong backreaction of the gauge sector tensors on the background dynamics. This transition results in the copious production of both scalar and tensor perturbations, which we study in detail. The gravitational wave signatures include a rich peak structure with a characteristic scale-dependent chirality, a compelling target for future gravitational wave detectors. Additionally, the peak in scalar perturbations may lead to the formation of primordial black holes, potentially accounting for a significant fraction of the observed dark matter abundance.

Adjacent type-I and -II proton superconductors in a rotation-powered pulsar are predicted to exist in a metastable state containing macroscopic and quantized flux tubes, respectively. Previous studies show that the type-I and -II regions are coupled magnetically, when macroscopic flux tubes divide dendritically into quantized flux tubes near the type-I-II interface, through a process known as flux branching. The studies assume that the normal-superconducting boundary is sharp, and the quantized flux tubes do not repel mutually. Here the sharp-interface approximation is refined by accounting for magnetic repulsion. It is found that flux tubes in the same flux tree cluster with a minimum-energy separation two to seven times less than that of isolated flux tubes. Neutron vortices pin and cluster about flux trees. We find that the maximum characteristic wave strain $h_0$ of the current quadrupole gravitational radiation emitted by a rectilinear array of clustered vortices exceeds by $(1+N_{\rm v,t})^{1/2}$ the strain $h_0 \sim 10^{-32}(f/30 {\rm Hz})^{5/2} (D/1 {\rm kpc})^{-1}$ emitted by uniformly distributed vortices, where $N_{\rm v,t}$ is the mean number of pinned vortices per flux tree, $f$ is the star's spin frequency, and $D$ is the star's distance from Earth. The factor $(1 + N_{\rm v,t})^{1/2}$ brings $h_0$ close to the sensitivity limit of the current generation of interferometric gravitational wave detectors under certain circumstances, specifically when flux branching forms relatively few (and hence relatively large) flux trees.

Open clusters offer unique opportunities to study stellar dynamics and evolution under the influence of their internal gravity, the Milky Way's gravitational field, and the interactions with encounters. Using the Gaia DR3 data for a catalog of open clusters within 500 parsecs that exhibit tidal features reported by the literature, we apply a novel method based on 3D principal component analysis to select a ''golden sample'' of nearby open clusters with minimal line-of-sight distortions. This approach ensures a systematic comparison of 3D and 2D structural parameters for tidally perturbed clusters. The selected golden sample includes Blanco 1, Melotte 20, Melotte 22, NGC 2632, NGC 7092, NGC 1662, Roslund 6 and Melotte 111. We analyze these clusters by fitting both 2D and 3D King Profiles to their stellar density distributions. Our results reveal systematic discrepancies: most of the golden sample clusters exhibit larger 3D tidal radii compared to their 2D counterparts, demonstrating that the 2D projection effects bias the measured cluster size. Furthermore, the 3D density profiles show stronger deviations from King profiles at the tidal radii ($\Delta \rho_{\rm 3D} > \Delta \rho_{\rm 2D}$), highlighting enhanced sensitivity to tidal disturbances. Additionally, we investigate the spatial distribution of cluster members relative to their bulk motion in the Galactic plane. We find that some clusters exhibit tidal features oriented perpendicular to their direction of motion, which can be attributed to the fact that the current surveys only detect the curved inner regions of the tidal features. In conclusion, this work offers a golden sample of nearby open clusters that are most reliable for 3D structure analysis and underscores the necessity of 3D analysis in characterizing OC morphological asymmetries, determining cluster size, and identifying tidal features.

In the third-generation (3G) gravitational-wave (GW) detector era, GW multi-messenger observations for binary neutron star merger events can exert great impacts on exploring the cosmic expansion history. Extending the previous work, we explore the potential of 3G GW standard siren observations in cosmological parameter estimation by considering their associated electromagnetic (EM) counterparts, including $\gamma$-ray burst (GRB) coincidence observations by the Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor and GW-triggered target-of-opportunity observations of kilonovae by different optical survey projects. During an assumed 10-year observation, we predict that the number of detectable GW-kilonova events is $\sim 4900$ with redshifts below $\sim 0.4$ under GW network and Large Synoptic Survey Telescope in the $i$ band, which is three times more than that of GW-GRB detections. For the cosmological analysis, we find that with the inclusion of GW-kilonova detections, the constraints on cosmological parameters from GW-EM detections are significantly improved compared to those from GW-GRB detections. In particular, GW-EM detections can tightly constrain the Hubble constant with a precision ranging from $0.076\%$ to $0.034\%$. Moreover, GW multi-messenger observations could effectively break the cosmological parameter degeneracies generated by the mainstream EM observations, CMB+BAO+SN (CBS). The combination of CBS and GW-EM can tightly constrain the equation of state parameters of dark energy $w$ in the $w$CDM model and $w_0$ in the $w_0w_a$CDM model with precisions of $0.72\%$ and $0.99\%$, respectively, meeting the standard of precision cosmology. In conclusion, GW multi-messenger observations could play a crucial role in helping solve the Hubble tension and probing the fundamental nature of dark energy.

We present the first extensive seismic modelling of SX Phe stars in the stellar system $\omega$ Cen. First, using the new values of reddening $E(B-V)$ and distance modulus $(m-M)_V$, and bolometric corrections from Kurucz model atmospheres, we determine the effective temperatures and luminosities of all SX Phe variables in $\omega$ Cen with available $(B-V)$ colours. Next, we carefully select SX Phe stars that have a frequency ratio strongly suggesting excitation of two radial modes, and, in addition, their preliminary pulsational models have the values of $(T_{\rm eff},~ L)$ consistent with observational determinations. For five double-mode radial pulsators, we perform an extensive seismic modeling using the Bayesian analysis based on Monte Carlo simulations. We study the effect of opacity tables and helium abundance. With the OPAL data and $Y=0.30$, we obtained masses in the range (1.0,~1.2) M$_{\odot}$, metallicity $Z\in(0.0007,~0.0029)$ and the age of about (1.9,~3.8) Gyr. The OP and OPLIB seismic models have always higher metallicites, sometimes outside the allowed range for $\omega$ Cen. In the case of three stars, we find seismic models within the observed range of $(T_{\rm eff},~L)$ with all three opacity tables. In the case of two stars, with the highest metallicity, seismic models computed with the OP and OPLIB tables are located far outside the observed error box. The OPAL seismic models follow the age$-$metallicity relation known for $\omega$ Cen from the literature.

We have created a large database of similarity information between sub-regions of Hubble Space Telescope images. These data can be used to assess the accuracy of image search algorithms based on computer vision methods. The images were compared by humans in a citizen science project, where they were asked to select similar images from a comparison sample. We utilized the Amazon Mechanical Turk system to pay our reviewers a fair wage for their work. Nearly 850,000 comparison measurements have been analyzed to construct a similarity distance matrix between all the pairs of images. We describe the algorithm used to extract a robust distance matrix from the (sometimes noisy) user reviews. The results are very impressive: the data capture similarity between images based on morphology, texture, and other details that are sometimes difficult even to describe in words (e.g., dusty absorption bands with sharp edges). The collective visual wisdom of our citizen scientists matches the accuracy of the trained eye, with even subtle differences among images faithfully reflected in the distances.

Cosmic inflation may exhibit stochastic periods during which quantum fluctuations dominate over the semi-classical evolution. Extracting observables in these regimes is a notoriously difficult program as quantum randomness makes them fully probabilistic. However, among all the possible quantum histories, the ones which are relevant for Cosmology are conditioned by the requirement that stochastic inflation ended. From an observational point of view, it would be more convenient to model stochastic periods as starting from the time at which they ended and evolving backwards in times. We present a time-reversed approach to stochastic inflation, based on a reverse Fokker-Planck equation, which allows us to derive non-perturbatively the probability distribution of the field values at a given time before the end of the quantum regime. As a motivated example, we solve the flat semi-infinite potential and derive a new and exact formula for the probability distribution of the quantum-generated curvature fluctuations. It is normalisable while exhibiting tails slowly decaying as a Levy distribution. Our reverse-time stochastic formalism could be applied to any inflationary potentials and quantum diffusion eras, including the ones that can lead to the formation of primordial black holes.

The Lyman-alpha (Ly{\alpha};1216 {\AA}) line is the brightest emission line in the quiescent solar spectrum and radiates a significant fraction of the available nonthermal energy during flares. Despite its importance, there is a lack of detailed studies of Ly{\alpha} spectral variability during flares. Recently, spectrally resolved Ly{\alpha} flare observations from the SORCE/SOLSTICE instrument have become available. This study examines Ly{\alpha} spectral variability and its relationship with HXR emission from nonthermal electrons, using observations of two M-class flares from SORCE/SOLSTICE and RHESSI. Imaging observations from STEREO/SECCHI EUVI and SDO/AIA provide further context. Enhancements across the Ly{\alpha} line profile were found to closely correlate with bursts of HXR emission, suggesting a primarily nonthermal origin. Red enhancement asymmetries at the peak of each flare were attributed to chromospheric evaporation, while blue wing enhancement and blue asymmetry were linked to a bright filament-eruption seen in SDO/AIA 1600 {\AA} images. These findings contribute to the understanding of spectral Ly{\alpha} variability during flares and highlight the need for future studies using a higher quality and quantity of spectral Ly{\alpha} flare observations. Such studies will further characterise the physical mechanisms driving Ly{\alpha} flare variability.

Eccentric cavities in circumbinary disks precess on timescales much longer than the binary orbital period. These long-lived steady states can be understood as trapped modes in an effective potential primarily determined by the binary quadrupole and the inner-disk pressure support, with associated frequencies $\omega_Q$ and $\omega_P$. Within this framework, we show that the ratio $\omega_P/\omega_Q$ is the main parameter determining the mode spectrum, and obtain a thorough understanding of it by systematically solving this problem with various degrees of sophistication. We first find analytical solutions for truncated power-law disks and use this insight in disks with smooth central cavities. Our main findings are: (i) The number of modes increases for thinner disks and more-equal-mass binaries. (ii) For 2D disks, the normalized ground-mode frequency, $\omega_0/(\omega_Q+\omega_P)$, decreases monotonically with the ratio $\omega_P/\omega_Q$. (iii) For thin disks, $\omega_P\ll\omega_Q$, the ground-mode frequency coincides with the maximum of the effective potential, which tracks the gravitational quadrupole frequency inside the inner-disk cavity, and is thus rather sensitive to the density profile of the cavity, where these modes are localized. (iv) For thick disks, $\omega_P\gg\omega_Q$, increasing pressure support anchors the peak of the effective potential at the inner cavity radius as the ground-mode extends farther out and its frequency decreases. (v) In agreement with numerical simulations, with $\omega_P/\omega_Q \simeq 0.1$, we find that disk precession is rather insensitive to the density profile and ground-mode frequencies for 3D disks are about half the value for 2D disks.

Hot dust-obscured galaxies (Hot DOGs), the most infrared (IR) luminous objects selected by the WISE all-sky mid-IR survey, have yielded a sample of intrinsically luminous quasars (QSOs) with obscured nuclear activity and hot dust temperatures. The molecular gas excitation properties have yet to be examined in detail under such extreme conditions. Here we study the most far-IR luminous WISE Hot DOG W2246-0526, focusing on the central host galaxy. Multi-J CO transition measurements at J=2-1, 5-4, 7-6, 12-11, and 17-16 provide the most well-sampled CO excitation ladder of any WISE Hot DOG to date, providing the first self-consistent modeling constraints on the molecular gas and dust properties. We implement a state-of-the-art TUrbulent Non-Equilibrium Radiative transfer model (TUNER) that simultaneously models both the line and dust continuum measurements. Due to a combination of high molecular gas densities and high kinetic temperatures, this extreme CO spectral line energy distribution peaks at J = 10 to 12, likely making this the most highly excited galaxy ever reported. We derive the alpha_CO conversion factors and conclude that (J=3-7) CO line luminosities trace the bulk of the molecular gas mass. W2246-0526 is a rapidly evolving system, with a high value of the molecular gas kinetic temperature versus dust temperature T_k / T_d ~ 3.9, reflecting previously reported shocks and outflows injecting kinetic energy within the central kpc of this host. This first comprehensive simultaneous modeling of both the molecular gas and dust in any object within the WISE-selected Hot DOG sample motivates obtaining well-sampled dust and line spectral energy distributions to better understand the conditions within these short-lived episodes in galaxy evolution that are associated with the most obscured supermassive black hole activity.

We investigate a quintessence axion model for dynamical dark energy, motivated in part by recent results from the Baryon Acoustic Oscillation (BAO) measurements of the Dark Energy Spectroscopic Instrument (DESI) and the Cosmic Microwave Background (CMB) observations from the Atacama Cosmology Telescope (ACT). By carefully treating the initial conditions and parameter sampling, we identify a preferred parameter space featuring a sub-Planckian axion decay constant and a relatively large axion mass, which naturally avoids the quality problem and remains consistent with the perturbative string conjecture. Our parameter scan also uncovers a trans-Planckian regime of theoretical interest, which is only mildly disfavored by observations. The results remain robust when DESI BAO data are combined with CMB and supernova observations. Finally, we discuss the possible connection between this model and the recently reported non-zero rotation of the CMB linear polarization angle, emphasizing the broader cosmological implications and the promising prospects for testing this scenario. We show that an $\mathcal{O}(1)$ electromagnetic anomaly coefficient is preferred by the strongest constraint, which is in full agreement with the minimal quintessence axion model.

Accretion and outflows are astrophysical phenomena observed across a wide range of objects, from white dwarfs to supermassive black holes. Developing a complete picture of these processes requires complementary studies across this full spectrum of jet-launching sources. Jet-interstellar medium (ISM) interaction sites near black hole X-ray binaries provide unique laboratories to study jet energetics. This work aims to detect and characterise the bow shock near one black hole X-ray binary, Cyg X-1, and then use this bow shock structure to parametrise the properties of the jet launched by Cyg X-1 over its lifetime. We used the MeerKAT radio telescope to investigate the bow shock structure formed by the interaction between the jets of Cyg X-1 and the ISM. We successfully detect the bow shock north of Cyg X-1 in the L and S bands and report its size and brightness. We present the spectral index distribution across the bow shock, which is in the range -0.9 to 0.4, with an error distribution (0.6 to 1.5) that peaks at unity. We determine that the unshocked ISM density is 6-7 cm^-3 for a temperature range of 10^4 to 3*10^6 K. This temperature range suggests that the velocity of the bow shock is 21 km/s to 364 km/s. The age of the Cyg X-1 jet responsible for the bow shock is 0.04 to 0.3 Myr, and the power of the jet is constrained to 2*10^31 ergs/s to 10^35 ergs/s. We also detect new morphological features of the bow shock in the S-band image. The comparison of archival H_alpha maps with the new radio observations hints at different regions of emission, different temperature ranges, and different ISM densities. The spectral index suggests a consistent emission origin across the structure. The ISM density around Cyg X-1 is on the higher end for Galactic environments, and our results indicate a lower jet energy transport rate than prior estimates.

After the inflationary phase, the universe enters the preheating phase, during which the inflaton field rolls down its potential and oscillates. When the potential significantly deviates from a parabolic shape at its minimum, these oscillations trigger an instability in the scalar perturbations, leading to their amplification. This phenomenon, known as self-resonance, has important implications in cosmology. Notably, since scalar perturbations couple to tensor perturbations at second order in the equations of motion, this amplification results in the production of Gravitational Waves (GWs), referred to as Scalar-Induced Gravitational Waves (SIGWs). In this study, we investigate the production of SIGWs during the preheating phase for a class of inflationary models known as $\alpha$-attractors, characterized by a single parameter $\alpha$. We focus on small values of this parameter, specifically $\alpha \sim O(10^{-1} - 10^{-4})$, where the self-resonance effect is particularly pronounced. We obtain lower bounds on this parameter, $\log_{10}(\alpha)>-3.54$ for the T-model and $\log_{10}(\alpha)>-3.17$ for the E-model, based on the energy density of SIGWs constrained by Big Bang nucleosynthesis, which ultimately translates into lower bounds on the tensor-to-scalar ratio, $r>9.61\times10^{-7}$ for the T-model and $r>2.25\times10^{-6}$ for the E-model.

Galactic archaeology relies on accurate stellar parameters to reconstruct the galaxy's history, including information on stellar ages. While the precision of data has improved significantly in recent years, stellar models used for age inference have not improved at a similar rate. In fact, different models yield notably different age predictions for the same observational data. In this paper, we assess the difference in age predictions of various widely used model grids for stars along the red giant branch. Using open source software, we conduct a comparison of four different evolution grids and we find that age estimations become less reliable if stellar mass is not known, with differences occasionally exceeding $80\%$. Additionally, we note significant disagreements in the models' age estimations at non-solar metallicity. Finally, we present a method for including theoretical uncertainties from stellar evolutionary tracks in age inferences of red giants, aimed at improving the accuracy of age estimation techniques used in the galactic archaeology community.

Analyses of stellar spectra, stellar populations, and transit light curves rely on grids of synthetic spectra and center-to-limb variations (limb darkening) from model stellar atmospheres. Extensive model grids from PHOENIX, a generalized non-LTE 1D and 3D stellar atmosphere code, have found widespread use in the astronomical community, however current PHOENIX/1D models have been substantially improved over the last decade. To make these improvements available to the community, we have constructed the NewEra LTE model grid consisting of 37438 models with $2300K \leq T_{eff} \leq 12000K$, $0.0\le log{(g)} \le 6.0$ metallicities [M/H] from $-4.0$ to $+0.5$, and for metallicities $-2.0 \le [M/H] \le 0.0$ additional $\alpha$ element variations from $-0.2 \le [\alpha/{\rm Fe}] \le +1.2$ are included. The models use databases of 851 million atomic lines and 834 billion molecular lines and employ the Astrophysical Chemical Equilibrium Solver for the equation of state. All models in the NewEra grid have been calculated in spherical symmetry because center-to-limb variation differences from plane-parallel models are quite large for giants and not insignificant for dwarfs. All model data are provided in the Hierarchical Data Format 5 (HDF5) format, including low and high sampling rate spectra. These files also include a variety of details about the models, such as the exact abundances and isotopic patterns used and results of the atomic and molecular line selection. Although the model structures have small differences with the previous grid generation, the spectra show significant differences, mostly due to the updates of the molecular line lists.

Stellar activity can be observed at different wavelengths in a variety of different activity indicators. We investigated the correlation between coronal and chromospheric emissions by combining X-ray data from stars detected in the eROSITA all-sky surveys (eRASS1 and eRASS:5) with Ca II infrared triplet (IRT) activity indices as published in the third Gaia data release (Gaia DR3). We specifically studied 24 300 and 43 200 stellar sources with reliable Ca II IRT measurement and X-ray detection in eRASS1 and eRASS:5, which is by far the largest stellar sample available so far. The largest detection fraction is obtained for highly active sources and stars of a late spectral type, while F-type and less active stars (as measured in the Ca II IRT) remain mostly undetected in X-rays. Also, the correlation is the strongest for late-type sources, while F-type stars show a rather weak correlation between the X-ray to bolometric flux ratio and the Ca II IRT activity index. The relation between the X-ray and Ca II IRT surface fluxes changes with the fractional X-ray flux without showing two separated branches as described in previous studies. For fast rotators, both activity indicators saturate at a similar Rossby number and the X-ray to bolometric flux ratio decreases faster than the IRT index for slower rotating stars. As a consequence, the ratio between X-ray and IRT fluxes is constant in the saturation regime and decreases for slow rotators.

Context. Observations with warm Spitzer and JWST revealed high and variable brightness in the planet 55 Cnc e. Aims. Inventory of the tidal effects on the rotational and orbital evolution of the planet 55 Cnc e enhanced by the nonzero orbital eccentricity. Methods. The creep-tide theory is used in simulations and dynamical analyses that explore the difficult trapping of the planet rotation in a 3:2 spin-orbit resonance and the most probable synchronization of the rotation. Results. The strong tidal dissipation of energy, enhanced by the non-zero orbital eccentricity, may explain the observed brightness anomalies. However, the strong dissipation should also circularize the orbit. The observed non-zero eccentricity, if true, would indicate that an unknown planet in a close orbital resonance with 55 Cnc e perturbing the motion of this planet should exist.

The chemical enrichment of X-ray-emitting hot halos has primarily been studied in closed-box galaxy clusters. Investigating the metal content of lower-mass, open systems can serve as a valuable tracer for understanding their dynamical history and the extent of chemical enrichment mechanisms in the Universe. In this context, we use an 85.6 ks XMM-Newton observation to study the spatial distribution of the abundance ratios of Mg, Si, and S with respect to Fe in the hot gas of the ram-pressure-stripped M86, which has undergone morphological transformations. We report that the chemical composition in the M86 galaxy core is more similar to the rest of the hot gaseous content of the Universe than to its stellar population. This result indicate that even extreme supersonic ram-pressure is insufficient to strip the inner part of a galaxy of its hot atmosphere. Comparison with other galaxies undergoing ram-pressure stripping suggests that stripping the "primordial" atmosphere of a galaxy requires a combination of ram-pressure stripping and strong radio-mechanical AGN activity. The X-ray emission structures within M86, the plume and the tail, are found to be relatively isothermal. We observe that the Mg/Fe ratio in the plume is $3.3\sigma$ higher than in the M86 galaxy core and is consistent with that in the M86 group outskirts and the Virgo ICM, suggesting that the plume might originate from the low-entropy group gas due to a galaxy-galaxy collision rather than from the ram-pressure stripping of the dense galaxy core.

The population of high-redshift radio galaxies (HzRGs) is still poorly studied because only a few of these objects are currently known. We here present the results of a pilot project of spectroscopic identification of HzRG candidates. The candidates are selected by combining low-frequency radio and optical surveys that cover a total of ~2,000 squared degrees using the dropout technique, that is, the presence of a redshifted Lyman break in their photometric data. We focused on 39 g-dropout sources, which is about one-third of the selected sources, that are expected to be at 3.0 < z < 4.5. We considered single and double radio sources separately and searched for g-dropout sources at the location of the midpoint of the radio structure for the latter. The host galaxy is expected to be located there. We confirm only one out of 29 candidate HzRG associated with an extended radio source. For the compact radio sources, we instead reach a success rate of 30% by confirming 3 out of 10 HzRG targets. The four newly discovered HzRGs show a wide range of spectral radio slopes. This supports the idea that not all HzRGs are ultrasteep radio sources (USSs). The criterion for USSs is most commonly used to find HzRGs, but this method only selects a subpopulation. We discuss various contamination sources for the objects that are selected with the Lyman-break method and conclude that they are likely mainly HzRGs, but with a Ly$\alpha$ line that is underluminous with respect to expectations.

The co-evolution of massive black holes (BHs) and their host galaxies is well-established within the hierarchical galaxy formation paradigm. Large-scale cosmological simulations are an ideal tool to study the repeated BH mergers, accretion and feedback that conspire to regulate this process. While such simulations are of fundamental importance for understanding the complex and intertwined relationship between BHs and their hosts, they are plagued with numerical inaccuracies at the scale of individual BH orbits. To quantify this issue, taking advantage of the $(100 \, h^{-1}\,\text{cMpc})^3$ FABLE simulation box, we track all individual BH mergers and the corresponding host galaxy mergers as a function of cosmic time. We demonstrate that BH mergers frequently occur prematurely, well before the corresponding merger of the host galaxies is complete, and that BHs are sometimes erroneously displaced from their hosts during close galaxy encounters. Correcting for these artefacts results in substantial macrophysical delays, spanning over several Gyrs, which are additional to any microphysical delays arising from unresolved BH binary hardening processes. We find that once the macrophysical delays are accounted for, high-mass BH merger events are suppressed, affecting the predictions for the BH population that may be observable with LISA and pulsar timing arrays. Furthermore, including these macrophysical delays leads to an increase in the number of observable dual active galactic nuclei, especially at lower redshifts, with respect to FABLE. Our results highlight the pressing need for more accurate modelling of BH dynamics in cosmological simulations of galaxy formation as we prepare for the multi-messenger era.

Baryonic cycling is reflected in the spatial distribution of metallicity within galaxies, yet gas-phase metallicity distribution and its connection with other properties of dwarf galaxies are largely unexplored. We present the first systematic study of radial gradients of gas-phase metallicities for a sample of 55 normal nearby star-forming dwarf galaxies (stellar mass $M_\star$ ranging from $10^7$ to $10^{9.5}\ M_\odot$), based on MUSE spectroscopic observations. We find that metallicity gradient shows a significant negative correlation (correlation coefficient $r \approx -0.56$) with $\log M_\star$, in contrast to the flat or even positive correlation observed for higher-mass galaxies. This negative correlation is accompanied by a stronger central suppression of metallicity compared to the outskirts in lower-mass galaxies. Among the other explored galaxy properties-including baryonic mass, star formation distribution, galaxy environment, regularity of the gaseous velocity field, and effective yield of metals $y_{\rm eff}$-only the velocity field regularity and $y_{\rm eff}$ show residual correlation with the metallicity gradient after controlling for $M_\star$, in the sense that galaxies with irregular velocity fields or lower $y_{\rm eff}$ tend to have less negative or more positive gradients. Particularly, a linear combination of $\log M_\star$ and $\log y_{\rm eff}$ significantly improves the correlation with metallicity gradient ($r \approx -0.68$) compared to $\log M_\star$ alone. The lack of correlation with environment disfavors gas accretion as a dominant factor. Our findings imply that metal mixing and transport processes, including but not limited to feedback-driven outflows, are more important than in-situ metal production in shaping the metallicity distribution of dwarf galaxies.

We present optical, radio, and X-ray observations of EP250108a/SN 2025kg, a broad-line Type Ic supernova (SN Ic-BL) accompanying an Einstein Probe (EP) fast X-ray transient (FXT) at $z=0.176$. EP250108a/SN 2025kg possesses a double-peaked optical light curve and its spectrum transitions from a blue underlying continuum to a typical SN Ic-BL spectrum over time. We fit a radioactive decay model to the second peak of the optical light curve and find SN parameters that are consistent with the SNe Ic-BL population, while its X-ray and radio properties are consistent with those of low-luminosity GRB (LLGRB) 060218/SN 2006aj. We explore three scenarios to understand the system's multi-wavelength emission -- (a) SN ejecta interacting with an extended circumstellar medium (CSM), (b) the shocked cocoon of a collapsar-driven jet choked in its stellar envelope, and (c) the shocked cocoon of a collapsar-driven jet choked in an extended CSM. All three models can explain the optical light curve and are also consistent with the radio and X-ray observations. We favor models (a) and (c) because they self-consistently explain both the X-ray prompt emission and first optical peak, but we do not rule out model (b). From the properties of the first peak in models (a) and (c), we find evidence that EP250108a/SN 2025kg interacts with an extended CSM, and infer an envelope mass $M_{\rm e} \sim 0.1\,\rm M_\odot$ and radius $R_{\rm e} \sim 4 \times 10^{13}$ cm. EP250108a/SN 2025kg's multi-wavelength properties make it a close analog to LLGRB 060218/SN 2006aj, and highlight the power of early follow-up observations in mapping the environments of massive stars prior to core collapse.

Recent observations have revealed the spectral feature of carbonaceous grains even in a very distant galaxy. We develop a state-of-the-art dust synthesis code by self-consistently solving molecule and dust formation in supernova (SN) ejecta that contain various elements in different layers. With a progenitor mass 25 Msun and explosion energy 10^{52} erg, we run the following four test calculations to investigate the impact of input physics. (i) With molecule formation solved, our SN model produces 8.45x10^{-2} Msun carbonaceous grains. (ii) If all available C and Si were initially depleted into CO and SiO molecules, respectively, the C grain mass could be underestimated by ~40%. In these two models producing 0.07 Msun 56Ni without mixing fallback, a large amount of silicates (0.260 Msun) created in O-rich layers are also ejected and likely to hide the spectral feature of carbonaceous grains. We then consider mixing-fallback that can reproduce the observed elemental abundance ratios of C-normal and C-enhanced extremely metal-poor stars in the Milky Way. (iii) In the former, the mass ratio of carbonaceous to silicate grains is still small (~0.3). However, (iv) in the latter (known as a ''faint SN'), while the C grain mass is unchanged (6.78x10^{-2} Msun), the silicate mass is reduced (9.98x10^{-3} Msun). Therefore, we conclude that faint SNe can be a significant carbonaceous dust factory in the early Universe.

The nearby (d=3.6 Mpc) starburst galaxy M82 has been studied for several decades by very long baseline interferometry (VLBI) networks such as e-MERLIN and the European VLBI Network (EVN). The numerous supernova remnants (SNRs), HII regions and other exotic transients make it a perfect laboratory for studying stellar evolution and the interstellar medium (ISM). Its proximity provides a linear resolution of 17 pc/arcsec, enabling decadal-time-scale variability and morphology studies of the tens of compact radio sources. In this proceedings, we describe new techniques developed in the last ten years that provide deeper, more robust imaging, enable in-band spectral index mapping, and allow wider fields of view to be imaged to find new radio sources.

Determining stellar ages is challenging, particularly for cooler main-sequence stars. Magnetic evolution offers an observational alternative for age estimation via the age-chromospheric activity (AC) relation. We evaluate the impact of metallicity on this relation using near one-solar-mass stars across a wide metallicity range. We analyze a sample of 358 solar-type stars with precise spectroscopic parameters determined through a line-by-line differential technique and with ages derived using Yonsei-Yale isochrones. We measured chromospheric activity (S-index) using high-quality HARPS spectra, calibrated to the Mount Wilson system, and converted to the $R^{\prime}_{\mathrm HK}(T_{\mathrm{eff}})$ index with a temperature-based photospheric correction. Our findings show that the AC relation for $R^{\prime}_{\mathrm HK}(T_{\mathrm{eff}})$ is strongly influenced by metallicity. We propose a new age-activity-metallicity relation for solar-type main-sequence (MS) stars ($\log{g} \gtrsim 4.2 $) with temperatures 5370 $\lesssim$ $T_{\mathrm{eff}}$ $\lesssim$ 6530 K and metallicities from -0.7 to +0.3 dex. We show that taking metallicity into account significantly enhances chromospheric ages' reliability, reducing the residuals' root mean square (RMS) relative to isochronal ages from 2.6 Gyr to 0.92 Gyr. This reflects a considerable improvement in the errors of chromospheric ages, from 53\% to 15\%. The precision level achieved in this work is also consistent with previous age-activity calibration from our group using solar twins.

As the lifetime of a black hole decreases, the energy of the Hawking radiation it emits increases, ultimately culminating in its disappearance through a powerful burst of gamma rays. For primordial black holes (PBHs) with an initial mass of $\sim 5\times10^{14}$ g, their lifespans are expected to end in the present epoch. Detecting such PBH bursts would provide compelling evidence of their existence. The Cherenkov Telescope Array (CTA) has the potential to observe these bursts at the high-energy end of the gamma-ray spectrum. To investigate this possibility, we conduct a study to evaluate the sensitivity of CTA to the local burst rate density of PBHs. Our results suggest that during a 5-year observational campaign, CTA could exclude a local burst rate density exceeding $\sim 36\ \mathrm{pc}^{-3}\ \mathrm{yr}^{-1}$, which represents an improvement of one order of magnitude over the upper limit set by the Large High Altitude Air Shower Observatory (LHAASO). In addition, we propose an observation strategy optimized for detecting PBH bursts.

Solar active regions (ARs) are crucial for understanding the long-term evolution of solar activities and predicting eruptive phenomena, including solar flares and coronal mass ejections. However, the cycle-dependent properties in the north-south asymmetry of ARs have not been fully understood. In this study, we investigate the hemispheric distribution of ARs from Carrington Rotation 1909 to 2278 (between 1996 May and 2023 November) by using three parameters that describe the magnetic field distribution of ARs: number, area, and flux. The main findings are as follows: (1) The three AR parameters show significant hemispheric asymmetry in cycles 23-25. The strong correlation between AR area and flux indicates that they can better reflect the intrinsic properties of solar magnetic field. (2) The correlation between sunspot activity and AR parameters varies in the two hemispheres across the different cycles. The AR parameters provide additional information for the variations in sunspot activity, which can better predict the intensity and cyclical changes of solar activity. (3) The variation in the fitting slope sign of the asymmetry index for AR parameters reflects periodic changes in hemispheric ARs, providing valuable insights into the activity of other stars. (4) Both the dominant hemisphere and the cumulative trend of AR parameters display a cycle-dependent behavior. Moreover, the trend variations of AR area and flux are similar, reflecting the long-term evolutionary characteristics of solar magnetic field. Our analysis results are relevant for understanding the hemispheric coupling of solar magnetic activity and its cyclic evolutionary patterns.

This study aims to detect and characterize quasi-periodic oscillations (QPOs) signals in X-ray observations of NGC 4151. We employed the Weighted Wavelet Z-transform (WWZ) and Lomb-Scargle periodogram (LSP) methods for our analysis. QPO signals with frequencies of 5.91 $\times 10^{-4}$ Hz and 5.68 $\times 10^{-4}$ Hz were detected in observations conducted by Chandra (ObsID 7830) in 2007 and XMM-Newton (ObsID 0761670301) in 2015, with confidence levels of 3.7 $\sigma$ and 3.3 $\sigma$, respectively. These signals are the first to be independently observed by two different telescopes over an eight-year period with closely matched frequencies. Most notably, the combined confidence level of the QPO signals from these two independent observations reaches an exceptional 5.2 $\sigma$, which is rare in astrophysical research and significantly strengthens our conviction in the authenticity of these signals. A detailed analysis of the observational data suggests that these QPO signals may be correlated with the properties of the central supermassive black hole. Additionally, spectral analysis of the observational data revealed no significant spectral differences between the QPO and non-QPO segments. These findings provide new insights into the X-ray variability mechanisms of the central black hole in NGC 4151 and offer a novel perspective for black hole mass estimation.

Black holes, both supermassive and stellar-mass, impact the evolution of their surroundings on a large range of scales. While the role of supermassive black holes is well studied, the effects of stellar-mass black holes on their surroundings, particularly in inducing structures in the interstellar medium (ISM), remain under explored. This study focuses on the black hole X-ray binary GRS 1915+105, renowned for its active jets, and the primary aim is to unveil and characterise the impact of GRS 1915+105 on its environment by identifying structures induced by jet-ISM interaction. Methods: We observed GRS 1915+105 with MeerKAT for a total exposure time of 14~hr, and we obtained the deepest image of GRS 1915+105 to date. Using a previously proposed self-similar model for large-scale jets, we inferred the properties of both the jets and the ISM, providing insights into the jet-ISM interaction site. Our observations revealed a bow shock structure near GRS 1915+105, likely induced by a jet interacting with the ISM and blowing an overpressured cavity in the medium. We constrained the ISM density to 100--160 particles\,cm$^{-3}$ while assuming a temperature range of 10$^4$--10$^6$\,K, which implies a bow shock expansion velocity of $20\,{\rm km\,s}^{-1}<\dot{L} <\,360\,{\rm km\,s}^{-1}$. We estimate that the jet responsible for the formation of the bow shock has an age between 0.09 and 0.22 Myr, and the time-averaged energy rate Conclusions: Our results confirm that in stellar-mass black holes, the energy dissipated through jets can be comparable to the accretion energy, and through the interaction of the jet with the ISM, such energy is transferred back to the environment. This feedback mechanism mirrors the powerful influence of supermassive black holes on their environments, underscoring the significant role a black hole's activity has in shaping its surroundings.

We study the asymptotic behaviour of the free, cold-dark matter density fluctuation bispectrum in the limit of small scales. From an initially Gaussian random field, we draw phase-space positions of test particles which then propagate along Zel'dovich trajectories. A suitable expansion of the initial momentum auto-correlations of these particles leads to an asymptotic series whose lower-order power-law exponents we calculate. The dominant contribution has an exponent of $-11/2$. For triangle configurations with zero surface area, this exponent is even enhanced to $-9/2$. These power laws can only be revealed by a non-perturbative calculation with respect to the initial power spectrum. They are valid for a general class of initial power spectra with a cut-off function, required to enforce convergence of its moments. We then confirm our analytic results numerically. Finally, we use this asymptotic behaviour to investigate the shape dependence of the bispectrum in the small-scale limit, and to show how different shapes grow over cosmic time. These confirm the usual model of gravitational collapse within the Zel'dovich picture.

Syn-glycolamide, a glycine isomer, has recently been detected in the G+0.693-0.027 molecular cloud. Investigations on its formation in the interstellar medium could offer insights into synthetic routes leading to glycine in prebiotic environments. Quantum chemical simulations on glycolamide (NH$_2$C(O)CH$_2$OH) formation on interstellar ice mantles, mimicked by a water ice cluster model, are presented. Glycolamide synthesis has been here modeled considering a stepwise process: the coupling between formaldehyde (H$_2$CO) and the radical of formamide (NH$_2$CO$^{\bullet}$) occurs first, forming the glycolamide precursor NH$_2$C(O)CH$_2$O$^{\bullet}$, which is then hydrogenated to give anti-glycolamide. We hypothesize that anti-to-syn interconversion will occur in conjunction with glycolamide desorption from the ice surface. The reaction barrier for NH$_2$C(O)CH$_2$O$^{\bullet}$ formation varies from 9 to 26 kJ mol$^{-1}$, depending on surface binding sites. Kinetic studies indicate that this reaction step is feasible in environments with a $T > 35~\text{K}$, until desorption of the reactants. The hydrogenation step leading to anti-glycolamide presents almost no energy barrier due to the easy H atom diffusion towards the NH$_2$C(O)CH$_2$O$^{\bullet}$ intermediate. However, it competes with the extraction of an H atom from the formyl group of NH$_2$C(O)CH$_2$O$^{\bullet}$, which leads to formyl formamide, NH$_2$C(O)CHO, and H$_2$. Nonetheless, according to our results, anti-glycolamide formation is predicted to be the most favored reactive channel.

Gaia Data Release 3 (GDR3) contains a wealth of information to advance our knowledge of stellar physics. In these lecture notes we introduce the data products from GDR3 that can be exploited by the stellar physics community. Then we visit different regions of the HR diagram, discuss the open scientific questions, and describe how GDR3 can help advance this particular topic. Specific regions include hot OB and A type stars, FGK main sequence, giants, and variable sources, low mass stars, and ultra-cool dwarfs. Examples of scientific exploitation are also provided. These lecture notes are accompanied by a 3-hour lecture presentation and a 3-hour practical session that are publicly available on the website of the Ecole Evry Schatzman 2023: Stellar physics with Gaia, https://ees2023.sciencesconf.org/, see Lectures and Hands-on Work.

We present a unique discovery of three new detected systems showing two different phenomena together. These are 2+2 quadruple stellar systems showing two eclipsing binaries as the inner pairs. And besides that, these systems were also found to exhibit the precession of the inner orbits causing the inclination changes manifesting themselves through the eclipse depth variations. We are not aware of any similar known system on the sky nowadays, hence our discovery is really unique. In particular these systems are: CzeV4315 = HD 228777 (periods 6.7391 d and 0.91932 d, inclination change of pair B of about 1.4deg/yr); ASASSN-V J075203.23-323102.7 = GDS_J0752031-323102 (8.86916 d + 2.6817 d, inclination change of pair B of about 1.03deg/yr, now only ellipsoidal variations); ASASSN-V J105824.33-611347.6 = TIC 465899856 (2.3304 d + 13.0033 d, inclination change of pair B, now undetectable). These systems provide us unique insight into the quadruple-star dynamics, including the orbit-orbit interaction, Kozai-Lidov cycles, and testing the stellar formation theories of these higher order multiples.

We formulate an effective field theory (EFT) of coupled dark energy (DE) and dark matter (DM) interacting through energy and momentum transfers. In the DE sector, we exploit the EFT of vector-tensor theories with the presence of a preferred time direction on the cosmological background. This prescription allows one to accommodate shift-symmetric and non-shift-symmetric scalar-tensor theories by taking a particular weak coupling limit, with and without consistency conditions respectively. We deal with the DM sector as a non-relativistic perfect fluid, which can be described by a system of three scalar fields. By choosing a unitary gauge in which the perturbations in the DE and DM sectors are eaten by the metric, we incorporate the leading-order operators that characterize the energy and momentum transfers besides those present in the conventional EFT of vector-tensor and scalar-tensor theories and the non-relativistic perfect fluid. We express the second-order action of scalar perturbations in real space in terms of time- and scale-dependent dimensionless EFT parameters and derive the linear perturbation equations of motion by taking into account additional matter (baryons, radiation). In the small-scale limit, we obtain conditions for the absence of both ghosts and Laplacian instabilities and discuss how they are affected by the DE-DM interactions. We also compute the effective DM gravitational coupling $G_{\rm eff}$ by using a quasi-static approximation for perturbations deep inside the DE sound horizon and show that the existence of momentum and energy transfers allow a possibility to realize $G_{\rm eff}$ smaller than in the uncoupled case at low redshift.

The outer solar system is theoretically predicted to harbour an undiscovered planet, often referred to as P9. Simulations suggest that its gravitational influence could explain the unusual clustering of minor bodies in the Kuiper Belt. However, no observational evidence for P9 has been found so far, as its predicted orbit lies far beyond Neptune, where it reflects only a faint amount of Sunlight. This work aims to find P9 candidates by taking advantage of two far-infrared all-sky surveys, which are IRAS and AKARI. The epochs of these two surveys were separated by 23 years, which is large enough to detect the ~3'/year orbital motion of P9. We use a dedicated AKARI Far-Infrared point source list for our P9 search - AKARI Monthly Unconfirmed Source List, which includes sources detected repeatedly only in hours timescale, but not after months. We search for objects that moved slowly between IRAS and AKARI detections given in the catalogues. First, we estimated the expected flux and orbital motion of P9 by assuming its mass, distance, and effective temperature to ensure it can be detected by IRAS and AKARI, then applied the positional and flux selection criteria to narrow down the number of sources from the catalogues. Next, we produced all possible candidate pairs whose angular separations were limited between 42' and 69.6', corresponding to the heliocentric distance range of 500 - 700 AU and the mass range of 7 - 17 Earth masses. There are 13 pairs obtained after the selection criteria. After image inspection, we found one good candidate, of which the IRAS source is absent from the same coordinate in the AKARI image after 23 years and vice versa. However, AKARI and IRAS detections are not enough to determine the full orbit of this candidate. This issue leads to the need for follow-up observations, which will determine the Keplerian motion of our candidate.

Understanding the epochs of cosmic dawn and reionisation requires us to leverage multi-wavelength and multi-tracer observations, with each dataset providing a complimentary piece of the puzzle. To interpret such data, we update the public simulation code, 21cmFASTv4, to include a discrete source model based on stochastic sampling of conditional mass functions and semi-empirical galaxy relations. We demonstrate that our new galaxy model, which parametrizes the means and scatters of well-established scaling relations, is flexible enough to characterize very different predictions from hydrodynamic cosmological simulations of high-redshift galaxies. Combining a discrete galaxy population with approximate, efficient radiative transfer allows us to self-consistently forward-model galaxy surveys, line intensity maps (LIMs), and observations of the intergalactic medium (IGM). Not only does each observable probe different scales and physical processes, but cross-correlation will maximise the information gained from each measurement by probing the galaxy-IGM connection at high-redshift. We find that a stochastic source field produces significant shot-noise in 21cm and LIM power spectra. Scatter in galaxy properties can be constrained using UV luminosity functions and/or 21cm power spectra, especially if astrophysical scatter is higher than expected (as might be needed to explain recent JWST observations). Our modelling pipeline is both flexible and computationally efficient, facilitating high-dimensional, multi-tracer, field-level Bayesian inference of cosmology and astrophysics during the first billion years.

The spectral variability of changing-look active galactic nuclei (CL-AGNs) occurred on timescales of years to tens of years, posing a significant challenge to the standard thin disk model. In this work, we propose a sandwich model, including an optically thick disk in the mid-plane (Disk 1) and two disks of low effective optical depth on both sides (Disk 2). These two types of disks are coupled with magnetic fields, which allow viscous torque interaction between them. As a consequence, the radial velocity of Disk 1 can increase by up to three orders of magnitude compared to the standard thin disk, leading to an equivalent decrease in the accretion timescale. Therefore, such a sandwich model can account for the rapid variability in CL-AGNs. In addition, we also discuss the influence of the magnetic pressure on Disk 2. When Disk 2 is dominated by the magnetic pressure, it resembles a "warm corona", which is responsible for the soft X-ray excess.

The formation of Saturn is modeled by detailed numerical simulations according to the core-nucleated accretion scenario. Previous models are enhanced to include the dissolution of accreting planetesimals, composed of water ice, rock, and iron, in the gaseous envelope of the planet, leading to a non-uniform composition with depth. The immiscibility of helium in metallic hydrogen layers is also considered. The calculations start at a mass $0.5$ Earth masses and are extended to the present day. At 4.57 Gyr, the model, proceeding outwards, has the following structure: (i) a central core composed of $100$% heavy elements and molecules, (ii) a region with decreasing heavy element mass fraction, down to a value of $0.1$, (iii) a layer of uniform composition with the helium mass fraction $Y$ enhanced over the primordial value, (iv) a helium rain region with a gradient in $Y$, (v) an outer convective, adiabatic region with uniform composition in which $Y$ is reduced from the primordial value, and (vi) the very outer layers where cloud condensation of the heavy elements occurs. Models of the distribution of heavy elements as a function of radius are compared with those derived to fit the observations of the Cassini mission, with rough qualitative agreement. The helium mass fraction in Saturn's outer layers is estimated to be around $20$%. Models are found which provide good agreement with Saturn's intrinsic luminosity and radius.

JWST galaxy deep spectral surveys provide a unique opportunity to trace a broad range of evolutionary features of galaxies and the intergalactic medium given the huge distance the photons are propagating. We have analyzed the spectral data of JWST galaxies up to a redshift of around 7 using the Kolmogorov technique, which is an efficient tool for testing the tiny comparative randomness properties of cumulative signals, that is, for distinguishing the contributions of regular and stochastic sub-signals. Our aim is to determine if certain identical spectral features of galaxies have undergone any distortions or systematic evolution across a broad range of redshifts. Our results indicate a change in the spectral properties of the sample galaxies at around z \simeq 2.7 at over a 99% confidence level.

The article describes observations of the crescent of Venus and other bright planets using a large camera obscura. The goal of the article is to demonstrate that these observations can be successfully performed. Achieving positive results depends on solving several key problems. The most significant of these is the difficulty of perceiving the extremely faint light of a planet on the camera obscura screen. This issue is resolved through the use of special directional screens. Two main types (translucent and reflective) are described in the article. The construction of a so-called ''artificial Venus'', designed to test directional screens and determine the average sensitivity of human vision, is also presented. \\ Other serious challenges include aiming the camera obscura at the celestial object and compensating for Earth's rotation. One of the methods discussed involves the use of a flat intermediate mirror and a special mount for its guidance.\\ The objective of the paper is fulfilled through the presentation of both visual and photographic observation results. In addition to Venus's crescent, observations of the Saturn's rings are also presented. The proposed design of the camera obscura, which incorporates a specialized projection system, enables the separation of its two functions: directing light from objects and focusing its energy. The elements performing these tasks are fully scalable. This can be used in the construction of modern telescopes. The article also comments on the possibility of observing the phases of Venus in the distant past and the important consequences resulting from this.

Producing stable $^{58}$Ni in Type Ia supernovae (SNe Ia) requires sufficiently high density conditions that are not predicted for all origin scenarios, so examining the distribution of $^{58}$Ni using the NIR [Ni II] 1.939 $\mu$m line may observationally distinguish between possible progenitors and explosion mechanisms. We present 79 telluric-corrected NIR spectra of 22 low-redshift SNe Ia from the Carnegie Supernova Project-II ranging from +50 to +505 days, including 31 previously unpublished spectra. We introduce the Gaussian Peak Ratio, a detection parameter that confirms the presence of the NIR [Ni II] 1.939 $\mu$m line in 8 SNe in our sample. Non-detections occur at earlier phases when the NIR Ni line has not emerged yet or in low signal-to-noise spectra yielding inconclusive results. Subluminous 86G-like SNe Ia show the earliest NIR Ni features around ~+50 days, whereas normal-bright SNe Ia do not exhibit NIR Ni until ~+150 days. NIR Ni features detected in our sample have low peak velocities ($v$~1200 km/s) and narrow line widths ($\leq$ 3500 km/s), indicating stable $^{58}$Ni is centrally located. This implies high density burning conditions in the innermost regions of SNe Ia and could be due to higher mass progenitors (i.e. near-$M_{ch}$). NIR spectra of the nearly two dozen SNe Ia in our sample are compared to various model predictions and paired with early-time properties to identify ideal observation windows for future SNe Ia discovered by upcoming surveys with Rubin-LSST or the Roman Space Telescope.

Many post-AGB star binaries are observed to have relatively high orbital eccentricities (up to 0.6). Recently, AC Her was observed to have a polar-aligned circumbinary disk. We perform hydrodynamic simulations to explore the impact of a polar-aligned disk on the eccentricity of a binary. For a binary system with central masses of 0.73 M_sun and 1.4 M_sun, we find that a disk with a total mass of 0.1 M_sun can enhance the binary eccentricity from 0.2 to 0.7 within 5000 years, or from 0.01 to 0.65 within 15000 years. Even if the disk mass is as low as 0.01 M_sun, the binary eccentricity grows within our simulation time while the system remains stable. These eccentricity variations are associated with the variations of the inclination between the disk and the binary orbit due to von Zeipel-Kozai-Lidov oscillations. The oscillations eventually damp and leave the binary eccentricity at a high value. The numerical results are in good agreement with analytical estimates. In addition, we examine the AC-Her system and find that the disk mass should be on the order of 10^(-3)M_sun for the disk to remain polar.

Despite a wealth of multi-wavelength, spatially resolved, time-domain solar activity data, an accurate and complete temporo-spatial solar flare census is unavailable, which impedes our understanding of the physics of flare production. We present an Automatically Labeled EUV and X-ray Incident SolarFlares (ALEXIS) pipeline, designed to decompose the X-Ray flux of the full solar disk into a minimum set of discrete regions on the Solar surface. ALEXIS returns an average RMSE between the XRS time series and the discrete EUV signals of 0.066 $\pm$ 0.036 for a randomly selected test bed sample of 1000 hour-long data segments from May 2010 - March 2020. Flare emission that requires multiple regions was found to be synchronous: flares occurring at the same time, sympathetic: flares separated by minutes, or needed to capture the background emission before and/or after the main flare. ALEXIS uses the original full resolution and cadence of both the Atmospheric Imaging Assembly Instrument and the GOES13-15 Solar X-Ray Imager. Comparison of the ALEXIS catalog with those produced by SWPC and SolarSoft show that these canonical databases need revisiting for 62$\%$ and 15$\%$ of the sub-sample, respectively. Additionally, we increased the number of flares reported by SWPC and SolarSoft by 15$\%$. Our pipeline misses 6.7$\%$ of the 1057 flare sub-sample and returns 5$\%$ of false positives from 1211 flares reported by ALEXIS. The ALEXIS catalog returns flare peak times, coordinates, the corrected scaled XRay magnitude, and the associated NOAA active region with a HARP identifier number independently from any external data products.

We present X-ray spectra ($0.7-20$ keV) of two high synchrotron-peaked blazars Mrk 421 and 1ES 1959+650 from simultaneous observations by the SXT and LAXPC instruments onboard \textit{AstroSat} and the \textit{Swift}-XRT during multiple intervals in 2016-19. The spectra of individual epochs are satisfactorily fitted by the log-parabola model. We carry out time-resolved X-ray spectroscopy using the \textit{AstroSat} data with a time resolution of $\sim$10 ks at all epochs, and study the temporal evolution of the best-fit spectral parameters of the log-parabola model. The energy light curves, with duration ranging from $0.5-5$ days, show intra-day variability and change in brightness states from one epoch to another. We find that the variation of the spectral index ($\alpha$) at hours to days timescale has an inverse relation with the energy flux and the peak energy of the spectrum, which indicates a harder-when-brighter trend in the blazars. The variation of curvature ($\beta$) does not follows a clear trend with the flux and has an anti-correlation with $\alpha$. Comparison with spectral variation simulated using a theoretical model of time variable nonthermal emission from blazar jets shows that radiative cooling and gradual acceleration of emitting particles belonging to an initial simple power-law energy distribution can reproduce most of the variability patterns of the spectral parameters at sub-day timescales.

The COronal DEnsity and Temperature (CODET) model is a physics-based model (Rodr\'iguez-G\'omez et al. 2018; Rodr\'iguez-G\'omez 2017) . This model uses the relationship between the magnetic field, density, temperature, and EUV emission. This model provides mean daily Solar Spectral Irradiance time series in EUV wavelengths in long time scales from days to solar cycles. The current manuscript presents the updated/new CODET model version 1.1. It uses observational datasets from SDO/EVE MEGS-A at $28.4 \ \mathrm{nm}$ and $21.1 \ \mathrm{nm}$ wavelengths to obtain the goodness-of-fit between them and the modeled SSI from April 30, 2010, to May 26, 2014. The model described well observational data during that period, with less than $20\%$ error in both wavelengths. Additionally, SSI predictions are provided using the new model parameters from July 1996 to October 2024, where SOHO/MDI and SDO/HMI photospheric magnetic field data are available. These predictions were compared with GOES/EUVS at $28.4 \ \mathrm{nm}$ and mean daily values of SDO/AIA at $21.1 \ \mathrm{nm}$ data, with errors of $\sim 26\%$ and $42\%$ for $28.4 \ \mathrm{nm}$ and $21.1 \ \mathrm{nm}$, respectively. The error analysis for model fitting and predictions shows how accurate the model predictions are. Thus, the CODET model provides a reliable estimate of the Solar Spectral Irradiance time series in EUV wavelengths where no observational data is available, e.g., after the SDO/EVE MEGS-A era.

Long gamma-ray bursts (LGRBs), including their subclasses of low-luminosity GRBs (LL-GRBs) and X-ray flashes (XRFs) characterized by low spectral peak energies, are known to be associated with broad-lined Type Ic supernovae (SNe Ic-BL), which result from the core collapse of massive stars that lose their outer hydrogen and helium envelopes. However, the soft and weak end of the GRB/XRF population remains largely unexplored, due to the limited sensitivity to soft X-ray emission. Here we report the discovery of a fast X-ray transient, EP250108a, detected by the Einstein Probe (EP) in the soft X-ray band at redshift $z = 0.176$, which was followed up by extensive multiband observations. EP250108a shares similar X-ray luminosity as XRF\,060218, the prototype of XRFs, but it extends GRBs/XRFs down to the unprecedentedly soft and weak regimes, with its $E_{\rm peak} \lesssim 1.8\,\mathrm{keV}$ and $E_{\rm iso} \lesssim 10^{49}\, \mathrm{erg}$, respectively. Meanwhile, EP250108a is found to be associated with SN\,2025kg, one of the most luminous and possibly magnetar-powered SNe Ic-BL detected so far. Modeling of the well-sampled optical light curves favors a mildly relativistic outflow as the origin of this event. This discovery demonstrates that EP, with its unique capability, is opening a new observational window into the diverse outcomes of death of massive stars.

Atmospheric turbulence degrades the quality of astronomical observations in ground-based telescopes, leading to distorted and blurry images. Adaptive Optics (AO) systems are designed to counteract these effects, using atmospheric measurements captured by a wavefront sensor to make real-time corrections to the incoming wavefront. The Fried parameter, r0, characterises the strength of atmospheric turbulence and is an essential control parameter for optimising the performance of AO systems and more recently sky profiling for Free Space Optical (FSO) communication channels. In this paper, we develop a novel data-driven approach, adapting machine learning methods from computer vision for Fried parameter estimation from a single Shack-Hartmann or pyramid wavefront sensor image. Using these data-driven methods, we present a detailed simulation-based evaluation of our approach using the open-source COMPASS AO simulation tool to evaluate both the Shack-Hartmann and pyramid wavefront sensors. Our evaluation is over a range of guide star magnitudes, and realistic noise, atmospheric and instrument conditions. Remarkably, we are able to develop a single network-based estimator that is accurate in both open and closed-loop AO configurations. Our method accurately estimates the Fried parameter from a single WFS image directly from AO telemetry to a few millimetres. Our approach is suitable for real time control, exhibiting 0.83ms r0 inference times on retail NVIDIA RTX 3090 GPU hardware, and thereby demonstrating a compelling economic solution for use in real-time instrument control.

Context. Star-forming galaxies emit {\gamma}rays with relatively low luminosity, but the study of their emission is no less captivating. While it is known that their {\gamma}-ray luminosity in the GeV band is strongly linked to their star formation, the origin of their emission at higher energies remains uncertain due to limited observations. Aims. Our aim is to assemble the largest possible sample of star-forming galaxies with potential detectability by the new-generation of Cherenkov telescopes. Methods. To achieve this, we compile a comprehensive sample of galaxies, including those previously detected by Fermi-LAT in the GeV energy range as well as a larger sample of star-forming galaxies in the Local Volume that have been cataloged in the near-infrared band. We estimate their {\gamma}-ray flux assuming a proportional relationship with their star formation rate, and then select the brightest candidates. The predicted spectra in the TeV band are derived using a simple empirical model normalized to the star formation rate and a model based on extrapolating the latest Fermi-LAT data to higher energies. The ground-based detectability of {\gamma}-ray emission from these sources is assessed through a comparison to the most recent instrument response functions. Results. Our investigation reveals that almost a dozen star-forming galaxies may be detectable by upcoming {\gamma}-ray telescopes. Conclusions. The observation of numerous star-forming galaxies in the TeV band is a fundamental piece of the panchromatic puzzle for understanding the physics inside these galaxies. The significant increase in the number of galaxies that can be studied in detail in the near future, particularly with the Cherenkov Telescope Array Observatory, promises a major step forward in the study of the conditions of acceleration and transport of cosmic rays in nearby extragalactic environments.

Motivated by recent discoveries of X-ray quasi-periodic eruptions, we revisit the collision of a black hole and an accretion disk. Assuming that they are orbiting a supermassive black hole in orthogonal orbits, we perform a general relativistic simulation of the collision, varying the relative velocity $V_0$ from $0.032c$ to $0.2c$ (where $c$ is the speed of light) with a variety of disk thickness and a realistic local density profile for the disk. Our findings indicate that the mass of the outflow matter from the disk, $m_{\rm ej}$, is slightly less than the expected value. Meanwhile, the typical energy associated with this outflow $E_{\rm ej}$ is $\sim m_{\rm ej}V_0^2$. Thus, the predicted peak luminosity from disk flares is approximately equal to the Eddington luminosity of the black hole, whereas the peak time and duration of the flares, which are $\propto m_{\rm ej}^{1/2}$, are shorter than that previously believed. We also demonstrate that the property of the outflow matter induced by the incoming and outgoing stages of the black hole collision is appreciably different. We find that a high mass accretion rate onto the black hole from the disk persists for a timescale of $\sim 10^6$ Schwarzschild time of the black hole after the collision for $V_0/c \lesssim 0.1$, making this long-term accretion onto the black hole the dominant emission process for black hole-disk collision events. Implications of these results are discussed.

Granulation in the photospheres of FGK-type stars induces variability in absorption lines, complicating exoplanet detection via radial velocities and characterisation via transmission spectroscopy. We aim to quantify the impact of granulation on the radial velocity and bisector asymmetry of stellar absorption lines of varying strengths and at different limb angles. We use 3D radiation-hydrodynamic simulations from MURaM paired with MPS-ATLAS radiative transfer calculations to synthesise time series' for four Fe I lines at different limb angles for a solar-type star. Our line profiles are synthesised at an extremely high resolution (R = 2,000,000), exceeding what is possible observationally and allowing us to capture intricate line shape variations. We introduce a new method of classifying the stellar surface into three components and use this to parameterise the line profiles. Our parameterisation method allows us to disentangle the contributions from p-modes and granulation, providing the unique opportunity to study the effects of granulation without contamination from p-mode effects. We validate our method by comparing radial velocity power spectra of our granulation time series to observations from the LARS spectrograph. We find that we are able to replicate the granulation component extracted from observations of the Fe I 617 nm line at the solar disk centre. We use our granulation-isolated results to show variations in convective blueshift and bisector asymmetry at different limb angles, finding good agreement with empirical results. We show that weaker lines have higher velocity contrast between granules and lanes, resulting in higher granulation-induced velocity fluctuations. Our parameterisation provides a computationally efficient strategy to construct new line profiles, laying the groundwork for future improvements in mitigating stellar noise in exoplanet studies.

The Pair Instability (PI) boundary is crucial for understanding heavy merging Black Holes (BHs) and the second mass gap's role in galactic chemical evolution. So far, no works have critically and systematically examined how rotation and mass loss affect the PI boundary or BH masses below it. Rapid rotation significantly alters stellar structure and mass loss, which is expected to have significant effects on the evolution of stellar models. We have previously derived a critical core mass independent of stellar evolution parameters, finding the BH (Pulsational) PI boundary at $M_{ CO, crit} = 36.3 M_\odot$ for a carbon-oxygen (CO) core. Using MESA, we model massive stars around the PI boundary for varying rotation rates and metallicities. We implement mechanical mass loss in MESA, studying its effects on massive stars in low-metallicity environments. Below $1/100$th $Z_\odot$, mechanical mass loss dominates over radiative winds. We check the BH-PI boundary for rapid rotators to confirm our critical core mass criterion and derive model fits describing rotation's impact on core and final masses. Fast rotators reach a point (typically $\Omega / \Omega_{crit} \approx 0.6$) where the entire star becomes chemically homogeneous, evolving like a stripped star. This lowers the maximum BH mass before PI to its critical core mass of $M_{CO, crit} = 36.3 M_\odot$, aligning with the bump feature in the BH mass distribution observed by LIGO/VIRGO.

The James Webb Space Telescope (JWST) discovered 79 transients out to $z$$\sim$4.8 through the JADES Transient Survey (JTS), but the JTS did not find any $z$$>$5 transients. Here, we present the first photometric evidence of a $z$$>$5 transient/variable source with JWST. The source, AT 2023adya, resides in a $z_{\mathrm{spec}}$$=$5.274 galaxy in GOODS-N, which dimmed from $m_{\rm F356W}$$=$26.05$\pm$0.02 mag to 26.24$\pm$0.02 mag in the rest-frame optical over approximately two rest-frame months, producing a clear residual signal in the difference image ($m_{\rm F356W}$$=$28.01$\pm$0.17 mag; SN$_\mathrm{var}$$=$6.09) at the galaxy center. Shorter-wavelength bands (F090W/F115W) show no rest-frame ultraviolet brightness change. Based on its rest-frame V-band absolute magnitude of M$_\mathrm{V}$$=$$-$18.48 mag, AT 2023adya could be any core-collapse supernova (SN) subtype or an SN Ia. However, due to low SN Ia rates at high redshift, the SN Ia scenario is unlikely. Alternatively, AT 2023adya may be a variable active galactic nucleus (AGN). However, the JWST NIRCam/Grism spectrum shows no broad H$\alpha$ emission line (FWHM$=$130$\pm$26 km s$^{-1}$), disfavoring the variable AGN scenario. It is also unlikely that AT 2023adya is a tidal disruption event (TDE) because the TDE models matching the observed brightness changes have low event rates. Although it is not possible to determine AT 2023adya's nature based on the two-epoch single-band photometry alone, this discovery indicates that JWST can push the frontier of transient/variable science past $z$$=$5 and towards the epoch of reionization.

Using high-resolution general relativistic magnetohydrodynamic (GRMHD) simulations, we investigate accretion flows around spinning black holes and identify three distinct accretion states. Our results naturally explain some of the complex phenomenology observed across the black hole mass spectrum. The magnetically arrested disk (MAD) state, characterized by strong magnetic fields (plasma-$\beta << 1$), exhibits powerful jets (of power $\sim10^{39}$ erg s$^{-1}$), highly variable accretion, and significant sub-Keplerian motion. On the other hand, weakly magnetized disks (plasma-$\beta >> 1$), known as the standard and normal evolution (SANE) state, show steady accretion with primarily thermal winds. An intermediate state bridges the gap between MAD and SANE regimes, with moderate magnetic support (plasma-$\beta \sim 1$) producing mixed outflow morphologies and complex variability. This unified framework explains the extreme variability of GRS 1915+105, the steady jets of Cyg X-1, and the unusually high luminosities (even super-Eddington based on stellar mass black hole) of HLX-1 without requiring super-Eddington mass accretion rates. Our simulations reveal a hierarchy of timescales that explain the rich variety of variability patterns, with magnetic processes driving transitions between states. Comparing two with three dimensional simulations demonstrates that while quantitative details differ, the qualitative features distinguishing different accretion states remain robust. The outflow power and variability follow a fundamental scaling relation with mass determined by the magnetic field configuration, demonstrating how similar accretion physics operates from stellar-mass X-ray binaries (XRBs) to intermediate mass black hole sources. This could be extrapolated further to supermassive black holes.

The Radial Acceleration Relation (RAR) follows from Milgromian gravitation (MoND). Velocity dispersion data of many dwarf spheroidal galaxies (dSphs) and galaxy clusters have been reported to be in tension with it. We consider the Generalized Poisson Equation (GPE), expressed in terms of the p-Laplacian, which has been applied in electrodynamics. We investigate whether it can address these tensions. From the GPE we derive a generalized RAR characterized by the $p$-parameter from the p-Laplacian and a velocity dispersion formula for a Plummer model. We apply these models to Milky Way and Andromeda dSphs and HIFLUGS galaxy clusters and derive a $p$-parameter for each dSph and galaxy cluster. We explore a relation of $p$ to the mass density of the bound system, and alternatively a relation of $p$ to the external field predicted from Newtonian gravity. This ansatz allows the deviations of dSphs and galaxy clusters from the RAR without introducing dark matter. Data points deviate from the Milgromian case, $p=3$, with up to $5\sigma$-confidence. Also, we find the model predicts velocity dispersions, each of which lies in the 1$\sigma$-range of their corresponding data point allowing the velocity dispersion to be predicted for dSphs from their baryonic density. The functional relation between the mass density of the bound system and $p$ suggests $p$ to increase with decreasing density. We find for the critical cosmological density $p(\rho_{\text{crit}}) = 12.27 \pm 0.39$. This implies significantly different behaviour of gravitation on cosmological scales. Alternatively, the functional relation between $p$ and the external Newtonian gravitational field suggests $p$ to decrease with increasing field strength.

Theoretical arguments and observations suggest that in massive halos ($>10^{12}\,M_\odot$), the circumgalactic medium (CGM) is dominated by a 'hot' phase with gas temperature near the virial temperature ($T \approx T_{\rm vir}$) and a quasi-hydrostatic pressure profile. Lower-mass halos are however unlikely to be filled with a similar quasi-static hot phase, due to rapid radiative cooling. Using the FIRE cosmological zoom simulations, we demonstrate that the hot phase is indeed sub-dominant at inner radii ($\lesssim 0.3\,R_{\rm vir}$) of $\lesssim 10^{12}\,M_\odot$ halos, and the inner CGM is instead filled with $T \ll T_{\rm vir}$ gas originating in outflows and inflows, with a turbulent velocity comparable to the halo virial velocity. The turbulent velocity thus exceeds the mass-weighted sound speed in the inner CGM, and the turbulence is supersonic. UV absorption features from such CGM trace the wide lognormal density distributions of the predominantly cool and turbulent volume-filling phase, in contrast with tracing localized cool 'clouds' embedded in a hot medium. We predict equivalent widths of $W_\lambda \sim 2\lambda v_c/c \sim 1A$ for a broad range of strong UV and EUV transitions (Mg II, C II, C IV, Si II-IV, O III-V) in sightlines through inner CGM dominated by turbulent pressure of $\lesssim L^*$ galaxies at redshifts $0 \leq z \lesssim 2$, where $\lambda$ is the transition wavelength, $v_{\rm c}$ is the halo circular velocity and $c$ is the speed of light. Comparison of our predictions with observational constraints suggests that star-forming dwarf and $\lesssim L^*$ galaxies are generally dominated by turbulent pressure in their inner CGM, rather than by thermal pressure. The inner CGM surrounding these galaxies is thus qualitatively distinct from that around quenched galaxies and massive disks such as the Milky-Way, in which thermal pressure likely dominates.

The mass of the Local Group (LG), comprising the Milky Way (MW), Andromeda (M31), and their satellites, is crucial for validating galaxy formation and cosmological models. Traditional virial mass estimates, which rely on line-of-sight (LoS) velocities and simplified infall assumptions, are prone to systematic biases due to unobserved velocity components and anisotropic kinematics. Using the TNG cosmological simulation, we examine two limiting cases: the \underline{minor infall} model -- ignoring perpendicular velocities to the LoS directions) and the \underline{major infall} model -- assuming purely radial motion towards the Center of Mass (CoM). Our simulations demonstrate that geometric corrections are vital: the minor-infall model underestimates the true mass, while the major-infall model overestimates it. By applying these calibrated corrections to observed dwarf galaxy kinematics within 1 Mpc of the LG's CoM, we derive a refined LG mass of $M_{\mathrm{LG}} = (2.99 \pm 0.60) \times 10^{12}\, M_\odot$. This finding aligns with predictions from the $\Lambda$CDM model, timing arguments, and independent mass estimates, resolving previous discrepancies. Our analysis highlights the importance of correcting for velocity anisotropy and offers a robust framework for dynamical mass estimation in galaxy groups.

We report the detection of thermal emission from and confirm the planetary nature of WD 1856+534b, the first transiting planet known to orbit a white dwarf star. Observations with JWST's Mid-Infrared Instrument (MIRI) reveal excess mid-infrared emission from the white dwarf, consistent with a closely-orbiting Jupiter-sized planet with a temperature of $186^{+6}_{-7}$ K. We attribute this excess flux to the known giant planet in the system, making it the coldest exoplanet from which light has ever been directly observed. These measurements constrain the planet's mass to no more than six times that of Jupiter, confirming its planetary nature and ruling out previously unexcluded low-mass brown dwarf scenarios. WD 1856+534b is now the first intact exoplanet confirmed within a white dwarf's "forbidden zone", a region where planets would have been engulfed during the star's red giant phase. Its presence provides direct evidence that planetary migration into close orbits, including the habitable zone, around white dwarfs is possible. With an age nearly twice that of the Solar System and a temperature akin to our own gas giants, WD 1856+534b demonstrates JWST's unprecedented ability to detect and characterize cold, mature exoplanets, opening new possibilities for imaging and characterizing these worlds in the solar neighborhood.

We present nuclear (100-150 pc) spectral energy distributions (SEDs) for a sample of 23 nearby luminous infrared galaxies hosting a total of 28 nuclei. We gather aperture photometry from high-resolution X-ray to submillimeter data for each nuclear region localized by ALMA observations of the dust continuum. We model the broadband SEDs using X-CIGALE. Binning the merging systems by interaction class, we find that the AGN fraction (fraction of AGN infrared luminosity to total infrared luminosity) appears enhanced in the late- and post-merger stages compared to early-stage mergers. Examining the relationship between X-ray emission and infrared emission of the nuclear regions, we find that the infrared emission in the nucleus is dominated by dust and AGN, with minimal contribution from stars. We also find that nuclear regions have higher X-ray hardness ratios than the host galaxies globally among both the AGN and non-AGN population. We highlight the similarities and differences in the SEDs of dual nuclei in five closely separated late-stage merging systems: Arp 220 ($d_\mathrm{nuc} \sim$ 0.5 kpc), NGC 6240 ($d_\mathrm{nuc} \sim$ 1 kpc), IRAS 07251-0248 ($d_\mathrm{nuc} \sim$ 2 kpc), IRAS F12112+0305 ($d_\mathrm{nuc} \sim$ 4 kpc), and IRAS F14348+1447 ($d_\mathrm{nuc} \sim$ 6 kpc). The SEDs for these resolved pairs are distinct, suggesting that the AGN state is much more susceptible to the stellar and dust content within the immediate circumnuclear ($<$150 pc) environment than to the host's global infrared luminosity or merger stage.

It is demonstrated that estimators of the angular power spectrum commonly used for the stochastic gravitational-wave background (SGWB) lack a closed-form analytical expression for the likelihood function and, typically, cannot be accurately approximated by a Gaussian likelihood. Nevertheless, a robust statistical analysis can be performed by extending the framework outlined in \cite{PRL} to enable the estimation and testing of angular power spectral models for the SGWB without specifying distributional assumptions. Here, the technical aspects of the method are discussed in detail. Moreover, a new, consistent estimator for the covariance of the angular power spectrum is derived. The proposed approach is applied to data from the third observing run (O3) of Advanced LIGO and Advanced Virgo.

Free space optical (FSO) communication using lasers is a rapidly developing field in telecommunications that can offer advantages over traditional radio frequency technology. For example, optical laser links may allow transmissions at far higher data rates, require less operating power and smaller systems and have a smaller risk of interception. In recent years, FSO laser links have been demonstrated, tested or integrated in a range of environments and scenarios. These include FSO links for terrestrial communication, between ground stations and cube-sats in low Earth orbit, between ground and satellite in lunar orbit, as part of scientific or commercial space relay networks, and deep space communications beyond the moon. The possibility of FSO links from and to the surface of Mars could be a natural extension of these developments. In this paper we evaluate some effects of the Martian atmosphere on the propagation of optical communication links, with an emphasis on the impact of dust on the total link budget. We use the output of the Mars Climate Database to generate maps of the dust optical depth for a standard Mars climatology, as well as for a warm (dusty) atmosphere. These dust optical depths are then extrapolated to a wavelength of 1.55 um, and translated into total slant path optical depths to calculate link budgets and availability statistics for a link between the surface and a satellite in a sun-synchronous orbit. The outcomes of this study are relevant to potential future missions to Mars that may require laser communications to or from its surface. For example, the results could be used to constrain the design of communication terminals suitable to the Mars environment, or to assess the link performance as a function of ground station location.

Recent spectroscopic observations of the [C\,{\tiny II}] 158$\,\mathrm{\mu m}$ fine-structure line of ionized carbon (C$^+$), using the Stratospheric Observatory for Infrared Astronomy (SOFIA), have revealed expanding [C\,{\tiny II}] shells in Galactic H\,{\tiny II} regions. We report the discovery of a bubble-shaped source (S144 in RCW79), associated with a compact H\,{\tiny II} region, excited by a single O7.5--9.5V/III star, which is consistent with a scenario that the bubble is still mostly ''filled'' with C$^+$. This indicates most likely a very early evolutionary state, in which the stellar wind has not yet blown material away, as it is the case for more evolved H\,{\tiny II} regions. Using the SimLine non-LTE radiative transfer code, the [C\,{\tiny II}] emission can be modeled to originate from three regions. First, a central H\,{\tiny II} region with little C$^+$ in the fully ionized phase, followed by two layers with gas density around $2500\,\mathrm{cm^{-3}}$ of partially photo-dissociated gas. The second layer is a slowly expanding [C\,{\tiny II}] shell with an expansion velocity of $\sim\,$$2.6\,\mathrm{km\,s^{-1}}$. The outermost layer exhibits a temperature and velocity gradient that produces the observed self-absorption features in the optically thick [C\,{\tiny II}] line ($\tau \sim 4$) leading to an apparent deficit in [C\,{\tiny II}] emission and a low ratio of [C\,{\tiny II}] to total far-infrared (FIR) emission. We developed a procedure to approximate the missing [C\,{\tiny II}] flux and find a linear correlation between [C\,{\tiny II}] and FIR without a [C\,{\tiny II}]-deficit. This demonstrates that at least some of the [C\,{\tiny II}]-deficit found in Galactic H\,{\tiny II} bubbles can be attributed to self-absorption.

This study is aimed to contribute to a more comprehensive understanding of the molecular hydrogen distribution in the galaxy M33 by introducing novel methods for generating high angular resolution (18.2$''$, equivalent to 75 pc) column density maps of molecular hydrogen ($N_{\rm H_2}$). M33 is a local group galaxy that has been observed with Herschel in the far-infrared wavelength range from 70 to 500 $\mu$m. Previous studies have presented total hydrogen column density maps ($N_{\rm H}$), using these FIR data (partly combined with mid-IR maps), employing various methods. We first performed a spectral energy distribution fit to the 160, 250, 350, and 500 $\mu$m continuum data obtain $N_{\rm H}$, using a technique similar to one previously reported in the literature. We also use a second method which involves translating only the 250 $\mu$m map into a $N_{\rm H}$ map at the same angular resolution. An $N_{\rm H_2}$ map via each method is then obtained by subtracting the HI component. Distinguishing our study from previous ones, we adopt a more versatile approach by considering a variable emissivity index, $\beta$ and dust absorption coefficient, $\kappa_0$. This choice enables us to construct a $\kappa_0$ map, thereby enhancing the depth and accuracy of our investigation of the hydrogen column density. We address the inherent biases and challenges within both methods (which give similar results) and compare them with existing maps available in the literature. Moreover, we calculate a map of the carbon monoxide CO-to-H$_2$ conversion factor ($X_\mathrm{CO}$ factor), which shows a strong dispersion around an average value of $1.8\times10^{20}\,\mathrm{cm^{-2}/(K\,km\,s^{-1})}$ throughout the disk. We obtain column density probability distribution functions (N-PDFs) from the $N_{\rm H}$, $N_{\rm H_2}$, and $N_{HI}$ maps and discuss their shape.

As part of the collaboration building a set of detectors for the new collider, our group was tasked with designing and building a large-scale cosmic ray detector, which was to complement the capabilities of the MPD (Dubna) detec-tor set. The detector was planned as a trigger for cosmic ray particles and to be used to calibrate and test other systems. Additional functions were to be the detection of pairs of high-energy muons originating from some parti-cle decay processes generated during collisions and con-tinuous observation of the cosmic muon stream in order to detect multi muons events. From the very beginning, the detector was designed as a scalable and universal device for many applications. The following work will present the basic features and parameters of the Modular COsmic Ray Detector (MCORD) and examples of its possible use in high energy physics, astrophysics and geology. Thanks to its universal nature, MCORD can be potential used as a fast trigger, neutron veto detector, muon detector and as a tool in muon tomography.

Gravitational-wave data from advanced-era interferometric detectors consists of background Gaussian noise, frequent transient artefacts, and rare astrophysical signals. Multiple search algorithms exist to detect the signals from compact binary coalescences, but their varying performance complicates interpretation. We present a machine learning-driven approach that combines results from individual pipelines and utilises conformal prediction to provide robust, calibrated uncertainty quantification. Using simulations, we demonstrate improved detection efficiency and apply our model to GWTC-3, enhancing confidence in multi-pipeline detections, such as the sub-threshold binary neutron star candidate GW200311_103121.

Recent results have shown that singularities can be avoided from the general relativistic standpoint in Lorentzian-Euclidean black holes by means of the transition from a Lorentzian to an Euclidean region where time loses its physical meaning and becomes imaginary. This dynamical mechanism, dubbed ''atemporality'', prevents the emergence of black hole singularities and the violation of conservation laws. In this paper, the notion of atemporality together with a detailed discussion of its implications is presented from a philosophical perspective. The main result consists in showing that atemporality is naturally related to conservation laws.

It is well known that the event horizon of the de Sitter universe can produce particles, and one can get sizable Hawking radiation by considering inflationary phases as de Sitter spacetimes with large Hubble rates. In this compact paper, we consider the graviton emission part of these radiations and assume that these graviton signals can exist in the current universe in the form of gravitational waves. We predict an energy density parameter of $\log_{10}(\Omega_{\rm GW} h^2) \sim \mathscr{O}(-25) - \mathscr{O}(-30)$ and its associated peak frequency $\log_{10}(f_{\rm peak}^0) \sim \mathscr{O}(6)-\mathscr{O}(5)$, depending on the reheating temperature. These signals occupy a frequency band below the ultrahigh-frequency regime and possess a detectable energy density, offering a promising target for future gravitational wave observatories. We believe that the detection of such signals would provide a compelling test of Hawking's radiation theory in a cosmological context.

Satellite-based estimates of greenhouse gas (GHG) properties from observations of reflected solar spectra are integral for understanding and monitoring complex terrestrial systems and their impact on the carbon cycle due to their near global coverage. Known as retrieval, making GHG concentration estimations from these observations is a non-linear Bayesian inverse problem, which is operationally solved using a computationally expensive algorithm called Optimal Estimation (OE), providing a Gaussian approximation to a non-Gaussian posterior. This leads to issues in solver algorithm convergence, and to unrealistically confident uncertainty estimates for the retrieved quantities. Upcoming satellite missions will provide orders of magnitude more data than the current constellation of GHG observers. Development of fast and accurate retrieval algorithms with robust uncertainty quantification is critical. Doing so stands to provide substantial climate impact of moving towards the goal of near continuous real-time global monitoring of carbon sources and sinks which is essential for policy making. To achieve this goal, we propose a diffusion-based approach to flexibly retrieve a Gaussian or non-Gaussian posterior, for NASA's Orbiting Carbon Observatory-2 spectrometer, while providing a substantial computational speed-up over the current operational state-of-the-art.

Searches for neutrino isocurvature usually constrain a specific linear combination of isocurvature perturbations. In this work, we discuss realistic cosmological scenarios giving rise to neutrino isocurvature. We show that in general both, neutrino and matter isocurvature perturbations are generated, whose ratio we parameterize by a newly introduced mixing angle. We obtain the first limits on this new mixing angle from PLANCK data, and discuss novel insights into the early Universe that could be provided by future measurements.

The ringdown phase of a binary black-hole merger encodes key information about the remnant properties and provides a direct probe of the strong-field regime of General Relativity. While quasi-normal mode frequencies and damping times are well understood within black-hole perturbation theory, their excitation amplitudes remain challenging to model, as they depend on the merger phase. The complexity increases for precessing black-hole binaries, where multiple emission modes can contribute comparably to the ringdown. In this paper, we investigate the phenomenology of precessing binary black hole ringdowns using the SXS numerical relativity simulations catalog. Precession significantly impacts the ringdown excitation amplitudes and the related mode hierarchy. Using Gaussian process regression, we construct the first fits for the ringdown amplitudes of the most relevant modes in precessing systems.

Detection of sub-GeV dark matter (DM) particles in direct detection experiments is inherently difficult, as their low kinetic energies in the galactic halo are insufficient to produce observable recoils of the heavy nuclei in the detectors. On the other hand, whenever DM particles interact with nucleons, they can be accelerated by scattering with galactic cosmic rays. These cosmic-ray-boosted DM particles can then interact not only through coherent elastic scattering with nuclei, but also through scattering with individual nucleons in the detectors and produce outgoing particles at MeV to GeV kinetic energies. The resulting signal spectrum overlaps with the detection capabilities of modern neutrino experiments. One future experiment is the Deep Underground Neutrino Experiment (DUNE) at the Sanford Underground Research Facility. Our study shows that DUNE has a unique ability to search for cosmic-ray boosted DM with sensitivity comparable to dedicated direct detection experiments in the case of spin-independent interactions. Importantly, DUNE's sensitivity reaches similar values of DM-nucleon cross sections also in the case of spin-dependent interactions, offering a key advantage over traditional direct detection experiments.

Dark matter (DM) candidates with very small masses, and correspondingly large number densities, have gained significant interest in recent years. These DM candidates are typically said to behave "classically". More specifically, they are often assumed to reside in an ensemble of coherent states. One notable exception to this scenario is when isocurvature fluctuations of the DM are produced during inflation (or more generally by any Bogoliubov transformation). In such contexts, the ultralight DM instead resides in a squeezed state. In this work, we demonstrate that these two scenarios can be distinguished via the statistics of the DM density fluctuations, such as the matter power spectrum and bispectrum. This provides a probe of the DM state which persists in the limit of large particle number and does not rely on any non-gravitational interactions of the DM. Importantly, the statistics of these two states differ when the modes of the squeezed state are all in-phase, as is the case at the end of inflation. Later cosmological dynamics may affect this configuration. Our work motivates future numerical studies of how cosmological dynamics may impact the initial squeezed state and the statistics of its density fluctuations.

Precision observations of orbital systems have recently emerged as a promising new means of detecting gravitational waves and ultra-light dark matter, offering sensitivity in new regimes with significant discovery potential. These searches rely critically on precise modeling of the dynamical effects of these signals on the observed system; however, previous analyses have mainly only relied on the secularly-averaged part of the response. We introduce here a fundamentally different approach that allows for a fully time-resolved description of the effects of oscillatory metric perturbations on orbital dynamics. We find that gravitational waves and ultra-light dark matter can induce large oscillations in the orbital parameters of realistic binaries, enhancing the sensitivity to such signals by orders of magnitude compared to previous estimates.

Recent Baryonic Acoustic Oscillation (BAO) measurements from the Dark Energy Spectroscopic Instrument (DESI) are mildly discrepant ($2.2\sigma$) with the Cosmic Microwave Background (CMB) when interpreted within $\Lambda$CDM. When analyzing these data with extended cosmologies this inconsistency manifests as a $\simeq3\sigma$ preference for sub-minimal neutrino mass or evolving dark energy. It is known that the preference for sub-minimal neutrino mass from the suppression of structure growth could be alleviated by increasing the optical depth to reionization $\tau$. We show that, because the CMB-inferred $\tau$ is negatively correlated with the matter fraction, a larger optical depth resolves a similar preference from geometric constraints. Optical depths large enough to resolve the neutrino mass tension ($\tau\sim0.09)$ also reduce the preference for evolving dark energy from $\simeq3\sigma$ to $\simeq1.5\sigma$. Conversely, within $\Lambda$CDM the combination of DESI BAO, high-$\ell$ CMB and CMB lensing yields $\tau = 0.090 \pm 0.012$. The required increase in $\tau$ is in $\simeq3-5\sigma$ tension with Planck low-$\ell$ polarization data when taken at face value. While there is no evidence for systematics in the large-scale Planck data, $\tau$ remains the least well-constrained $\Lambda$CDM parameter and is far from its cosmic variance limit. The importance of $\tau$ for several cosmological measurements strengthens the case for future large-scale CMB experiments as well as direct probes of the epoch of reionization.

We identified known Trans-Neptunian Objects (TNOs) and Centaurs in the complete Dark Energy Survey (DES) year six catalog (DES Y6) through the Sky Body Tracker (SkyBoT) tool. We classified our dataset of 144 objects into a widely used 4-class taxonomic system of TNOs. No such previous classification was available in the literature for most of these objects. From absolute magnitudes and average albedos, an estimation of the diameters of all these objects is obtained. Correlations involving colours, orbital parameters, dynamical classes and sizes are also discussed. In particular, our largest reddest object has a diameter of $390^{+68}_{-53}$ km and our largest cold classical, $255^{+19}_{-17}$ km. Also, a weak correlation between colour and inclination is found within the population of resonant TNOs in addition to weak correlations between colour and phase slope in different bands.

It has been suggested that a gravitational slingshot from the hypothetical Planet 9 (P9) could explain the unusually large velocity of meteor CNEOS 2014-01-08. I show that this explanation does not work because P9 can at most provide an insignificant 0.25 km/s of the object's 42 km/s asymptotic heliocentric velocity and at most a 7.6 degree deflection due to P9's low orbital speed and non-zero radius. Furthermore, the hypothesis requires an encounter with two planets that is trillions of times more unlikely than CNEOS 2014-01-08 simply being fast from the beginning.

During the late stages of a binary neutron star inspiral, dynamical tides induced in each star by its companion become significant and should be included in complete gravitational-wave (GW) modeling. We investigate the coupling between the tidal field and quasi-normal modes in hybrid stars and show that the discontinuity mode ($g$-mode)--intrinsically associated with first-order phase transitions and buoyancy--can rival the contribution of the fundamental $f$-mode. We find that the $g$-mode overlap integral can reach up to $\sim 10\%$ of the $f$-mode value for hybrid star masses in the range 1.4-2.0$M_{\odot}$, with the largest values generally associated with larger density jumps. This leads to a GW phase shift due to the $g$-mode of $\Delta \phi_g \lesssim 0.1$-$1$ rad (i.e., up to $\sim$5\%-10\% of $\Delta \phi_f$), with the largest shifts occurring for masses near the phase transition. At higher masses, the shifts remain smaller and nearly constant, with $\Delta \phi_g \lesssim 0.1$ rad (roughly $\sim 1\%$ of $\Delta \phi_f$). These GW shifts may be relevant even at the design sensitivity of current second-generation GW detectors in the most optimistic cases. Moreover, if a $g$-mode is present and lies near the $f$-mode frequency, neglecting it in the GW modeling can lead to systematic biases in neutron star parameter estimation, resulting in radius errors of up to $1\%-2\%$. These results show the importance of dynamical tides to probe neutron stars' equation of state, and to test the existence of dense-matter phase transitions.

Recent observational advances, such as Gaia DR3 GSP-Spec, have highlighted the potential of chemical abundances in tracing and revealing the structure of spiral arms. Building on these studies, we aim to trace the Milky Way's inner spiral arms using chemical abundance data from the Gaia-ESO Survey (GES). By mapping over-densities in [Fe/H] and [Mg/Fe], we seek to identify spiral arms in both radial and vertical planes, detect substructures, and compare our results with recent Galactic chemical evolution models. We used chemical abundance data from the Gaia-ESO Survey to create spatial maps of [Fe/H], [Mg/H], and [Mg/Fe] excess across the Galactic inner disc. We compared our results with the spiral arm models proposed by Spitoni et al. (2023) and Barbillon et al. (2024). For the first time, the inner spiral arms were revealed using chemical abundance patterns. We detected [Fe/H] enhancements and [Mg/Fe] under-abundances that consistently trace the Scutum and Sagittarius arms. A connecting spur between these arms is observed in the [Mg/H] plane. The alignment between our observations and the results of our 2D chemical evolution models reinforces the significance of spiral arm transits in driving both azimuthal and radial variations in chemical abundances. Our results confirm that spiral arms can be traced using stellar chemical abundances with GES data, providing a new perspective on the structure of the inner Galaxy. The consistency between enhanced [Fe/H] and lower [Mg/Fe] ratios, as observed in previous studies, further strengthens the reliability of our findings. The observed spur, bifurcation, and vertical substructures align well with recent models and studies, indicating that chemical maps can significantly contribute to our understanding of Galactic spiral arms.

Using 15 years of data from the Fermi Large Area Telescope (Fermi-LAT), we performed a comprehensive analysis on the gamma-ray binary HESS J0632+057. Its spectrum in 0.1-300 GeV band is well described by a power law model with an index of $2.40\pm0.16$, leading to an energy flux of (5.5$\pm$1.6$)\times$ 10$^{-12}$ erg cm$^{-2}$ s$^{-1}$. The GeV Spectral Energy Distribution (SED) of HESS J0632+057 hints for a spectral turn-over between $\sim$10-100 GeV. Orbital analysis reveals a flux enhancement during the phase range of 0.2-0.4, consistent with the X-ray and TeV light curves, indicating an origin of a common particle population. We carried out six deep radio observations on HESS J0632+057 with the Five-hundred-meter Aperture Spherical Telescope (FAST), evenly distributed across its orbit, reaching a detection sensitivity of 2$\mu$Jy. However, no radio pulsation was detected within these observations. The absence of radio pulsation may be attributed to the dense stellar wind environment of HESS J0632+057.

Cosmic-ray air shower detection with the low-frequency part of the Square Kilometre Array (SKA) radio telescope is envisioned to yield very high precision measurements of the particle composition of cosmic rays between $10^{16}$ and $10^{18}$ eV. This is made possible by the extreme antenna density of the core of SKA-Low, surpassing the current most dense radio air shower observatory LOFAR by over an order of magnitude. In order to make these measurements, the technical implementation of this observation mode and the development of reconstruction methods have to happen hand-in-hand. As a first lower limit of what is obtainable, we apply the current most precise reconstruction methods as used at LOFAR to a first complete simulation of air shower signals for the SKA-Low array. We describe this simulation setup and discuss the obtainable accuracy and resolution. A special focus is put on effects of the dynamic range of the system, beamforming methods to lower the energy threshold, as well as the limits to the mass composition accuracy given by statistical and systematic uncertainties.

We report the discovery of an isolated millisecond pulsar M15O (J2129+1210O) from the globular cluster M15 (NGC 7078) with a period of $\sim$11.06686 ms and a dispersion measure of $\sim$67.44 cm$^{-3}$ pc. Its spin period is so close to the $10^{\text{th}}$ harmonic of the bright pulsar M15A ($\sim$11.06647 ms) and thus missed in previous pulsar search. We suggest adding the spectrum in the pulsar candidate diagnostic plot to identify new signals near the harmonics. M15O has the first spin frequency derivative and the second spin frequency derivative,being 1.79191(5) $\times$ $10^{-14}$ Hz $s^{-2}$ and 3.3133(6)$\times$ $10^{-23}$ Hz $s^{-3}$, respectively. Its projected distance from the optical centre of M15 is the closest among all the pulsars in M15. The origin can be something from the center of the massive and core-collapsed globular cluster M15.

The combination of independent cosmological datasets is a route towards precision and accurate inference of the cosmological parameters if these observations are not contaminated by systematic effects. However, the presence of unknown systematics present in differrent datasets can lead to a biased inference of the cosmological parameters. In this work, we test the consistency of the two independent tracers of the low-redshift cosmic expansion, namely the supernovae dataset from Pantheon$+$ and the BAO dataset from DESI DR2 using the distance duality relation which is a cornerstone relation in cosmology under the framework of General Relativity. We find that these datasets violate the distance duality relation and show a signature of redshift evolution, hinting toward unaccounted physical effects or observational artifacts. Coincidentally this effect mimics a redshift evolving dark energy scenario when supernovae dataset and DESI datasets are combined without accounting for this inconsistency. Accounting for this effect in the likelihood refutes the previous claim of evidence of non-cosmological constant as dark energy model from DESI DR2, and shows a result consistent with cosmological constant with $w_0= -0.92\pm 0.08$ and $w_a= -0.49^{+0.33}_{-0.36}$. This indicates that the current conclusion from DESI DR2 in combination with Pantheon$+$ is likely due to the combination of two inconsistent datasets resulting in precise but inaccurate inference of cosmological parameters. In the future, tests of this kind for the consistency between different cosmological datasets will be essential for robust inference of cosmological parameters and for deciphering unaccounted physical effects or observational artifacts from supernovae and BAO datasets.

We address the question whether the magneto-rotational instability (MRI) can operate in the near-surface shear layer (NSSL) of the Sun and how it affects the interaction with the dynamo process. Using hydromagnetic mean-field simulations of $\alpha\Omega$-type dynamos in rotating shearing-periodic boxes, we show that for negative shear, the MRI can operate above a certain critical shear parameter. This parameter scales inversely with the equipartition magnetic field strength above which $\alpha$ quenching set in. Like the usual $\Omega$ effect, the MRI produces toroidal magnetic field, but in our Cartesian cases it is found to reduce the resulting magnetic field strength and thus to suppress the dynamo process. In view of the application to the solar NSSL, we conclude that the turbulent magnetic diffusivity may be too large for the MRI to be excited and that therefore only the standard $\Omega$ effect is expected to operate.

Aims. We aim to characterize the properties of the inner companion of the S-type AGB star pi1 Gru, and to identify plausible future evolution scenarios for this triple system. Methods. We observed pi1 Gru with ALMA and VLT/SPHERE. In addition, we collected archival photometry data and used the Hipparcos-Gaia proper motion anomaly. We derive the best orbital parameters from Bayesian inference. Results. The inner companion, pi1 Gru C was located at 37.4 +/- 2.0 mas from the primary in June-July 2019 (projected separation of 6.05 +/- 0.55 au at 161.7 +/- 11.7 pc). The best orbital solution gives a companion mass of 0.86 (+0.22/-0.20) Msun (using the derived mass of the primary), and a semi-major axis of 7.05 (+0.54/-0.57) au. This leads to an orbital period of 11.0 (+1.7/-1.5) yr. The best solution is an elliptical orbit with eccentricity e = 0.35 (+0.18/-0.17), but a circular orbit cannot be totally excluded. The close companion can either be a K1V (F9.5V/K7V) star or a white dwarf. The ultraviolet and millimeter continuum photometry are consistent with the presence of an accretion disk around the close companion. The ultraviolet emission could then either originate in hot spots in an overall cooler disk, or also from a hot disk in case the companion is a white dwarf. Conclusions. Though the close companion and the AGB star are interacting, and an accretion disk is observed around the companion, the mass-accretion rate is too low to cause a Ia supernova but could produce novae every ~900 yr. Short wavelength spatially resolved observations are needed to further constrain the nature of the C companion. Searches for close-in companions similar to this system will help to better understand the physics of mass- and angular-momentum transfer, and orbital evolution in the late evolutionary stages.

Symbiotic stars, interacting binaries composed of a cool giant and a hot compact companion, exhibit complex variability across the electromagnetic spectrum. Over the past decades, large-scale photometric and spectroscopic surveys from ground- and space-based observatories have significantly advanced their discovery and characterization. These datasets have transformed the search for new symbiotic candidates, providing extensive time-domain information crucial for their classification and analysis. This review highlights recent observational results that have expanded the known population of symbiotic stars, refined classification criteria, and enhanced our understanding of their variability. Despite these advances, fundamental questions remain regarding their long-term evolution, mass transfer and accretion processes, or their potential role as progenitors of Type Ia supernovae. With ongoing and upcoming surveys, the coming years promise new discoveries and a more comprehensive picture of these intriguing interacting systems.

V596 Pup is a detached eclipsing binary containing two A1 V stars in a 4.596 d period orbit with a small eccentricity and apsidal motion, previously designated as VV Pyxidis. We use new light curves from the Transiting Exoplanet Survey Satellite (TESS) and published radial velocities to determine the physical properties of the component stars. We find masses of 2.098 +/- 0.021 Msun and 2.091 +/- 0.018 Msun, and radii of 2.179 +/- 0.008 Rsun and 2.139 +/- 0.007 Rsun. The measured distance to the system is affected by the light from a nearby companion star; we obtain 178.4 +/- 2.5 pc. The properties of the system are best matched by theoretical predictions for a subsolar metallicity of Z = 0.010 and an age of 570 Myr. We measure seven significant pulsation frequencies from the light curve, six of which are consistent with delta Scuti pulsations and one of which is likely of slowly-pulsating B-star type.

RZ Cha is a detached eclipsing binary containing two slightly evolved F5 stars in a circular orbit of period 2.832 d. We use new light curves from the Transiting Exoplanet Survey Satellite (TESS) and spectroscopic orbits from Gaia DR3 to measure the physical properties of the component stars. We obtain masses of 1.488 +/- 0.011 Msun and 1.482 +/- 0.011 Msun, and radii of 2.150 +/- 0.006 Rsun and 2.271 +/- 0.006 Rsun. An orbital ephemeris from the TESS data does not match published times of mid-eclipse from the 1970s, suggesting the period is not constant. We measure a distance to the system of 176.7 +/- 3.7 pc, which agrees with the Gaia DR3 value. A comparison with theoretical models finds agreement for metal abundances of Z = 0.014 and Z = 0.017 and an age of 2.3 Gyr. No evidence for pulsations was found in the light curves. Future data from TESS and Gaia will provide more precise masses and constraints on any changes in orbital period.

In this work, we analyze the ongoing brightening of the poorly studied symbiotic star V4141 Sgr and examine its long-term variability. We present new low-resolution spectroscopic observations of the system in its bright state and combine them with multi-color photometric data from our observations, ASAS-SN, ATLAS, and Gaia DR3. To investigate its long-term evolution, we also incorporate historical data, including photographic plates, constructing a light curve spanning more than a century. Our analysis reveals that V4141 Sgr has undergone multiple outbursts, with at least one exhibiting characteristics typical of "slow" symbiotic novae. The current outburst is characterized by the ejection of optically thick material and possibly bipolar jets, a phenomenon observed in only a small fraction of symbiotic stars. These findings establish V4141 Sgr as an intriguing target for continued monitoring.

This paper derives and summarizes the analytical conditions for lunar ballistic capture and constructs ballistic lunar transfers based on these conditions. We adopt the Sun-Earth/Moon planar bicircular restricted four-body problem as the dynamical model to construct lunar transfers. First, the analytical conditions for ballistic capture are derived based on the relationship between the Keplerian energy with respect to the Moon and the angular momentum with respect to the Moon, summarized in form of exact ranges of the Jacobi energy at the lunar insertion point. Both sufficient and necessary condition and necessary condition are developed. Then, an optimization method combined with the analytical energy conditions is proposed to construct ballistic lunar transfers. Simulations shows that a high ballistic capture ratio is achieved by our proposed method (100$\%$ for direct insertion and $99.15\%$ for retrograde insertion). Examining the obtained ballistic lunar transfers, the effectiveness of the analytical energy conditions is verified. Samples of our obtained lunar transfers achieves a lower impulse and shorter time of flight compared to two conventional methods, further strengthening the advantage of our proposed method.

We present a ''cyclic zoom'' method to capture the dynamics of accretion flows onto black holes across a vast range of spatial and temporal scales in general relativistic magnetohydrodynamic (GRMHD) simulations. In this method, we cyclically zoom out (derefine) and zoom in (refine) the simulation domain while using a central mask region containing a careful treatment of the coarsened fluid variables to preserve the small-scale physics, particularly the magnetic field dynamics. The method can accelerate GRMHD simulations by $\gtrsim 10^5$ times for problems with large scale separation. We demonstrate the validity of the technique using a series of tests, including spherically symmetric Bondi accretion, the Blandford-Znajek monopole, magnetized turbulent Bondi accretion, accretion of a magnetized rotating torus, and the long-term evolution of an accreting torus about both Schwarzschild and Kerr black holes. As applications, we simulate Bondi and rotating torus accretion onto black holes from galactic scales, covering an extremely large dynamic range. In Bondi accretion, the accretion rate is suppressed relative to the Bondi rate by $\sim(10r_\mathrm{g}/r_\mathrm{B})^{1/2}$ with a feedback power of $\sim 0.01 \dot{M} c^2$ for vanishing spin, and $\sim 0.1 \dot{M} c^2$ for spin $a\approx0.9$. In the long-term evolution of a rotating torus, the accretion rate decreases with time as $\dot{M}\propto t^{-2}$ on timescales much longer than the viscous timescale, demonstrating that our method can capture not only quasi-steady problems but also secular evolution. Our new method likewise holds significant promise for applications to many other problems that need to cover vast spatial and temporal scales.

Radiometers are crucial instruments in radio astronomy, forming the primary component of nearly all radio telescopes. They measure the intensity of electromagnetic radiation, converting this radiation into electrical signals. A radiometer's primary components are an antenna and a Low Noise Amplifier (LNA), which is the core of the ''receiver'' chain. Instrumental effects introduced by the receiver are typically corrected or removed during calibration. However, impedance mismatches between the antenna and receiver can introduce unwanted signal reflections and distortions. Traditional calibration methods, such as Dicke switching, alternate the receiver input between the antenna and a well-characterised reference source to mitigate errors by comparison. Recent advances in Machine Learning (ML) offer promising alternatives. Neural networks, which are trained using known signal sources, provide a powerful means to model and calibrate complex systems where traditional analytical approaches struggle. These methods are especially relevant for detecting the faint sky-averaged 21-cm signal from atomic hydrogen at high redshifts. This is one of the main challenges in observational Cosmology today. Here, for the first time, we introduce and test a machine learning-based calibration framework capable of achieving the precision required for radiometric experiments aiming to detect the 21-cm line.

Ultra-short-period (USP) planets represent a unique class of exoplanets characterized by their tight orbits and relatively low masses, with some also exhibiting unusually high iron fractions. Previous work (Becker et al, 2021) proposed a dynamical pathway wherein planets can migrate inward due to drag from sub-Keplerian gas during episodic FU Orionis (FU Ori) outbursts, an abrupt accretion phenomenon exhibited by young stellar objects, thereby potentially populating USP orbits. However, the implications of this migration process on the structural and compositional evolution of these planets remain unexplored. In this work, we model the response of a planet's surface material to the high disk temperatures characteristic of an FU Ori event and compute the fraction of an Earth-like planet's mass that will be lost due to vaporization and subsequent turbulent diffusion of gaseous molecules during the FU Ori event. We find that low-mass planets may lose a substantial fraction of their mantle mass during FU Ori events, potentially contributing to the observed prevalence of low-mass, iron-rich USP planets.

Constant-roll inflation is a distinctive class of phenomenological inflationary models in which the inflaton's rate of roll remains constant. It provides an exact solution that is compatible with the latest observational constraints and offers a natural framework for enhancing the curvature power spectrum, which is relevant to the formation of primordial black holes. In this paper, I review constant-roll inflation in memory of Alexei Starobinsky.

Quasars are variable and their variability can both constrain their physical properties and help to identify them. We look for ways to efficiently identify quasars exhibiting consistent variability over multi-year time-scales, based on a small number of epochs. Using infrared (IR) is desirable to avoid bias against reddened objects. We compare the apparent brightness of known quasars that have been observed with two IR surveys, covering up to a twenty-year baseline: the Two Micron All Sky Survey (2MASS; 1997-2001) and the VISTA Hemisphere Survey (VHS; 2009-2017). We look at the previous studies of the selected variable quasars to see if their variable behaviour is known and when available we use multi-epoch monitoring with the Zwicky Transient Facility (ZTF) to obtain a measure of optical variability of individual objects. We build a sample of ~2500 quasars that show statistically significant variability between the 2MASS and VHS. About 1500 of these come from the new Quaia sample based on Gaia spectra and about 1/3 of these have hardly been studied. The Quaia sample constitutes the main product of this work. Based on ensemble variability and structure function analysis we demonstrate that the selected objects in our sample are representative of the typical quasar population and show behaviour, consistent with other quasar samples. Our analysis strengthens previous results, for example that variability decreases with the rest-frame wavelength and that it exhibits peaks for certain absolute magnitudes of the quasars. Similarly, the structure function shows an increase in variability for rest-frame time lags below ~1500 d and a decrease for longer lags, just like in previous studies. Our selection, even though it is based on two epochs only, seems to be surprisingly robust, showing up to ~11% contamination by quasars that show stable non-variable behaviour in ZTF.

We apply the caustic technique to samples of galaxy clusters stacked in redshift space to estimate the gravitational potential in the cluster's outer region and test modifications to the standard theory of gravity. We separate 122 galaxy clusters from the HeCS-SZ, HeCS-redMapper, and HeCS samples into four samples with increasing mass; we estimate four robust, highly constraining caustic profiles for these samples. The caustic masses of the four stacked clusters agree within $ 10\%$ with the corresponding median values of each cluster sample. By adopting the NFW density profile to model the gravitational potential, we recover the caustic profile $\mathcal{A}(r)$ up to radius $r_{\rm p} \sim 4.0\, {\rm Mpc}$. This comparison is a first-order validation of the mass-concentration relation for galaxy clusters expected in the $\Lambda$CDM model. We thus impose this correlation as a prior in our analysis. Based on our stacked clusters, we estimate the value of the filling factor, which enters the caustic technique, $\mathcal{F}_{\beta} = 0.59\pm 0.05$; we derive this value using real data alone and find it consistent with the value usually adopted in the literature. We then use the caustic profiles $\mathcal{A}(r)$ of the stacked clusters to constrain the chameleon gravity model. We find that the caustic profiles provide a stringent upper limit of $|f_{\rm R0}| \lesssim 4 \times 10^{-6}$ at $95\%$ C.L. limits in the $f(\mathcal{R})$ scenario. The formalism developed here shall be further refined to test modifications to gravity in the extended outer weak gravitational regions of galaxy clusters.

One of the most striking manifestations of orderly behavior emerging out of complex interactions in any astrophysical system is the 11-year cycle of sunspots. However, direct sunspot observations and reconstructions of long-term solar activity clearly exhibit amplitude fluctuations beyond the decadal timescale -- which may be termed as supradecadal modulation. Whether this long-term modulation in the Sun's magnetic activity results from nonlinear mechanisms or stochastic perturbations remains controversial and a matter of active debate. Utilizing multi-millennial scale kinematic dynamo simulations based on the Babcock-Leighton paradigm -- in the likely (near-critical) regime of operation of the solar dynamo -- we demonstrate that this supradecadal modulation in solar activity cannot be explained by nonlinear mechanisms alone; stochastic forcing is essential for the manifestation of observed long-term fluctuations in the near-critical dynamo regime. Our findings substantiate some independent observational and theoretical investigations, and provide additional insights into temporal dynamics associated with a plethora of natural phenomena in astronomy and planetary systems arising from weakly nonlinear, non-deterministic processes.

Context. The emerging population of inert black hole binaries (BHBs) provides a unique opportunity to constrain black hole (BH) formation physics. These systems are composed of a stellar-mass BH in a wide orbit around a non-degenerate star with no observed Xray emission. Inert BHBs allow for narrow constraints to be inferred on the natal kick and mass loss during BH-forming core-collapse events. Aims. In anticipation of the upcoming BLOeM survey, we aim to provide tight constraints on BH natal kicks by exploiting the full parameter space obtained from combined spectroscopic and astrometric data to characterize the orbits of inert BHBs. Multi-epoch spectroscopy from the BLOeM project will provide measurements of periods, eccentricities, and radial velocities for inert BHBs in the SMC, which complements Gaia astrometric observations of proper motions. Methods. We present a Bayesian parameter estimation framework to infer natal kicks and mass loss during core-collapse from inert BHBs, accounting for all available observables, including the systemic velocity and its orientation relative to the orbital plane. The framework further allows for circumstances when some of the observables are unavailable, such as for the distant BLOeM sources which preclude resolved orbits. Results. With our new framework, we are able to distinguish between BH formation channels, even in the absence of a resolved orbit. In cases when the pre-explosion orbit can be assumed to be circular, we precisely recover the parameters of the core-collapse, highlighting the importance of understanding the eccentricity landscape of pre-explosion binaries, both theoretically and observationally. Treating the near-circular, inert BHB, VFTS 243, as a representative of the anticipated BLOeM systems, we constrain the natal kick to less than 27 km/s and the mass loss to less than 2.9 Msun within a 90% credible interval.

As the closest Earth-like exoplanet within the habitable zone of the M-dwarf star TRAPPIST-1, TRAPPIST-1e exhibits a magnetic field topology that is dependent on space weather conditions. Variations in these conditions influence its habitability and contribute to its radio emissions. Our objective is to analyze the response of different terrestrial magnetosphere structures of TRAPPIST-1e to various space weather conditions, including events analogous to coronal mass ejections (CMEs). We assess its habitability by computing the magnetopause standoff distance and predict the resulting radio emissions using scaling laws. This study provides some priors for future radio observations. We perform three-dimensional magnetohydrodynamic (MHD) simulations of the TRAPPIST-1e system using the PLUTO code in spherical coordinates. Our analysis indicates that the predicted habitability and radio emission of TRAPPIST-1e strongly depend on the planet's magnetic field intensity and magnetic axis inclination. Within sub-Alfvenic, super-Alfvenic, and transitional stellar wind regimes, the radio emission intensity positively correlates with both planetary magnetic field strength and axial tilt, while planetary habitability, quantified by the magnetopause standoff distance, shows a positive correlation with magnetic field strength and a negative correlation with magnetic axis tilt...

Radio astronomy is part of radio science that developed rapidly in recent decades. In the research of radio astronomy, pulsars have always been an enduring popular research target. To find and observe more pulsars, large radio telescopes have been built all over the world. In this paper, we present our studies on pulsars in M15 and NGC 6517 with FAST, including monitoring pulsars in M15 and new pulsar discoveries in NGC 6517. All the previously known pulsars in M15 were detected without no new discoveries. Among them, M15C was still detectable by FAST, while it is assumed to fade out due to precession [1]. In NGC 6517, new pulsars were continues to be discovered and all of them are tend to be isolated pulsars. Currently, the number of pulsars in NGC 6517 is 17, much more than the predicted before [2].

With current observational methods it is not possible to directly measure the magnetic field in the solar corona with sufficient accuracy. Therefore, coronal magnetic field models have to rely on extrapolation methods using photospheric magnetograms as boundary conditions. In recent years, due to the increased resolution of observations and the need to resolve non-force-free lower regions of the solar atmosphere, there have been increased efforts to use magnetohydrostatic (MHS) field models instead of force-free extrapolation methods. Although numerical methods to calculateMHS solutions can deal with non-linear problems and hence provide more accurate models, analytical three-dimensional MHS equilibria can also be used as a numerically relatively "cheap" complementary method. In this paper, we present an extrapolation method based on a family of analytical MHS equilibria that allows for a transition from a non-force-free region to a force-free region. We demonstrate how asymptotic forms of the solutions can help to increase the numerical efficiency of the method. Through both artificial boundary condition testing and a first application to observational

A heliocentric dust ring on Venus orbit was discovered following observations by the Helios spacecraft, and then confirmed thanks to observations by STEREO and the Parker Solar Probe. The impact risk it poses needs to be evaluated for any spacecraft crossing the ring. This study aims to provide a first model of the dust ring, in terms of distribution of particles (including size distribution), velocity, density of the ring, and deduce a first estimation of the impact risk to spacecrafts crossing the ring. We seek to describe the orbits of dust particles in the ring. We explore a first simple model, that leads us to propose a second, more elaborate, model. This model is then populated by particles that we integrate for 2000 years. We demonstrate that the dust ring will persist over the next 2000 years, only slightly extending radially and perpendicularly to the Venus orbital plane. We show that particles tend to accumulate at Venus orbit, but that along it the differences in density is negligible. We compute the number of particles we can expect to find in the ring. Finally, as an example, we apply this model to Bepi-Colombo to obtain a first estimate of the impact flux in function of radius and mass, for radii between 2 $\mu$m and 2 cm (i.e. for masses between 10^-2 kg and 10^-14 kg). We also present the impact velocity and direction of impacts with respect to Bepi-Colombo. We are able to conclude that the ring seems to present a low risk for spacecrafts using Venus as a gravity assist.

It is explained why ultra-diffuse galaxies (UDGs), a subset of (IC 3475)-type galaxies, do not have unexpectedly large sizes but large sizes that are in line with expectations from the curved size-luminosity relation defined by brighter early-type galaxies (ETGs). UDGs extend the faint end of the (absolute magnitude, $\mathfrak{M}$)-log(S\'ersic index, $n$) and $\mathfrak{M}$-(central surface brightness, $\mu_{\rm 0}$) relations defined by ETGs, leading to the large effective half-light radii, $R_{\rm e}$, in UDGs. It is detailed how the scatter in $\mu_{\rm 0}$, at a given $\mathfrak{M}$, relates to variations in the galaxies' values of $n$ and effective surface brightness, $\mu_{\rm e}$. These variations map into changes in $R_{\rm e}$ and produce the scatter about the $\mathfrak{M}$-$R_{\rm e}$ relation at fixed $\mathfrak{M}$. Similarly, the scatter in $\mathfrak{M}$, at fixed $\mu_{\rm 0}$ and $n$, can be mapped into changes in $R_{\rm e}$. The increased scatter about the faint end of the $\mathfrak{M}$-$R_{\rm e}$ relation and the smaller scatter about $\mathfrak{M}$-(isophotal radii, $R_{\rm iso}$) relations are explained. Artificial and potentially misleading size-luminosity relations for UDGs are also addressed. The suggestion that there may be two types of UDG appears ill-founded, arising from the scatter about the $\mathfrak{M}$-$\mu_{\rm 0}$ relation, which persists at all magnitudes. Hopefully, the understanding presented here will prove helpful for interpreting the many low surface brightness galaxies that the Large Synoptic Survey Telescope will detect.

Dynamics of stellar mass black holes (sBHs) embedded in active galactic nuclei (AGNs) could produce highly eccentric orbits near the central supermassive black hole, leading to repeated close encounters that emit gravitational waves in the LIGO frequency band. Many works have focused on the mergers of sBH in the disk that produce gravitational waves; however, sBHs in hyperbolic orbits also emit gravitational-wave \bremss{} that can be detected by ground-based interferometers like LIGO. In this work, we analyze the scattering of sBHs in an AGN disk as they migrate inside the disk, focusing on gravitational-wave \bremss{} emission. We determine how the gravitational-wave emission depends on the different parameters of the scattering experiments, such as the mass of the supermassive black hole and the sBH migration rate and mass ratio. We find that scattering with detectable gravitational-wave \bremss{} is more frequent around lower mass SMBHs ($\sim 10^{5-6}$M$_\odot$). We then conduct a suite of Monte Carlo simulations and estimated the rate for ground-based gravitational-wave detections to be in the range of 0.08 - 1194 $\text{Gpc}^{-3} \text{ yr}^{-1}$, depending on migration forces and detection thresholds, with large uncertainties accounting for variations in possible AGN environments. The expected rate for our {\tt Fiducial} parameters is 3.2 $\text{Gpc}^{-3} \text{ yr}^{-1}$. Finally, we provide first-principle gravitational wave templates produced by the encounters.

The class-transition Galactic X-ray binary IGR J17091--3624 was simultaneously monitored by the IXPE and NuSTAR satellites. We present a detailed spectro-polarimetric study of the source using data from both satellites covering the period from March 7-10, 2025. A polarimetric analysis in the $2$-$8$~keV band using a model-independent method reveals a significant detection of polarization degree (PD) of $(11.3\pm2.35)\%$ at a polarization angle (PA) of $82^\circ.7\pm5^\circ.96$ (significant at $>4\sigma$). The model-dependent polarization analysis using the polconst and polpow models yields consistent values of PD and PA. In both methods, an energy-dependent increasing trend of PD is observed. In the $6$-$8$~keV band, a maximum PD of $(29.9\pm8.46)\%$ is detected at a PA of $88^\circ.0\pm8^\circ.15$ (significant at $>3\sigma$) . The joint spectral analysis using IXPE and NuSTAR data in the $2$-$70$~keV band was performed with four different sets of phenomenological and physical models. Our results indicate a strong dominance of non-thermal photons originating from a 'hot' Compton cloud, suggesting that the source was in a hard spectral state. Spectral fitting with the physical kerrbb and TCAF models provides an estimate of the black hole mass $M_{\rm BH} = 14.8^{+4.7}_{-3.4}~M_\odot$ and dimensionless spin parameter $a^* \sim 0.54$.

The Galactic transient black hole candidate MAXI J1834-021 exhibited 'faint' outbursting activity for approximately $10$ months following its discovery on February 5, 2023. We study the evolution of both the temporal (hard and soft band photon count rates, hardness ratios, and QPO frequencies) and spectral properties of the source using NICER data between March 7 and October 4, 2023. The outburst profile and the nature of QPOs suggest that the source underwent a mini-outburst following the primary outburst. A monotonic evolution of low-frequency QPOs from higher to lower frequencies is observed during the primary outbursting phase. Both phenomenological (diskbb plus powerlaw) and physical (Two Component Advective Flow) model fitted spectral studies suggest that during the entire epoch, the source remained in harder spectral states, with a clear dominance of nonthermal emissions from the 'hot' Compton cloud. The 2023 outbursting activity of MAXI J1834$-$021 can be classified as a combination of double 'failed' outbursts, as no softer spectral states were observed.

The rising phase of the 2023-24 outburst of the recently discovered bright transient black hole candidate Swift J1727.8-1613 was monitored by \textit{Insight}-HXMT. We study the evolution of hard ($4$-$150$ keV) and soft ($2$-$4$ keV) band photon count rates, the hardness ratio (HR), and QPO frequencies using daily observations from the HXMT/LE, ME, and HE instruments between August 25 and October 5, 2023. The QPO frequency is found to be strongly correlated with the soft-band X-ray count rates, and spectral photon indices. In contrast, a strong anti-correlation is observed between HR and QPO frequency, as well as between HR and photon index. Based on the evolution of the QPO frequency, the rising phase of the outburst is subdivided into six parts, with parts 1-5 fitted using the propagating oscillatory shock (POS) solution to understand the nature of the evolution from a physical perspective. The best-fitted POS model is obtained with a black hole mass of $13.34\pm0.02~M_\odot$. An inward-propagating shock with weakening strength (except in part 4) is observed during the period of our study. The POS model-fitted mass of the source is further confirmed using the QPO frequency ($\nu$)-photon index ($\Gamma$) scaling method. From this method, the estimated probable mass of Swift J1727.8-1613 is obtained to be $13.54\pm1.87~M_\odot$.

We have been developing a CdZnTe immersion grating for a compact high-dispersion mid-infrared spectrometer (wavelength range 10--18 $\mu$m, spectral resolution $R = \lambda/\Delta \lambda > 25,000$, operating temperature $T < 20$ K). Using an immersion grating, the spectrometer size can be reduced to $1/n$ ($n$: refractive index) compared to conventional diffraction gratings. CdZnTe is promising as a material for immersion gratings for the wavelength range. However, the refractive index $n$ of CdZnTe has not been measured at $T < 20$ K. We have been developing a system to precisely measure $n$ at cryogenic temperatures ($T \sim 10$ K) in the mid-infrared wavelength range. As the first result, this paper reports the temperature dependence of $n$ of CdZnTe at the wavelength of 10.68 $\mu$m. This system employs the minimum deviation method. The refractive index $n$ of CdZnTe is measured at temperatures of \( T = 12.57, 22.47, 50.59, 70.57, \text{ and } 298 \, \text{K} \). We find that $n$ of CdZnTe at $\lambda =$ 10.68 $\mu$m is $2.6371 \pm 0.0022$ at $12.57 \pm 0.14$ K, and the average temperature dependence of $n$ between 12.57 $\pm$ 0.14 K and 70.57 $\pm$ 0.23 K is $\Delta n/\Delta T = (5.8 \pm 0.3) \times 10^{-5}$ K$^{-1}$.

Ultralight (or fuzzy) dark matter (ULDM) is an alternative to cold dark matter. A key feature of ULDM is the presence of solitonic cores at the centers of collapsed halos. These would potentially increase the drag experienced by supermassive black hole (SMBH) binaries, changing their merger dynamics and the resulting gravitational wave background. We perform detailed simulations of high-mass SMBH binaries in the soliton of a massive halo. We find more rapid decay than previous simulations and semi-analytic approximations. We confirm expectations that the drag depends strongly on the ULDM particle mass, finding masses greater than $10^{-21}$ eV could potentially alleviate the final parsec problem and that ULDM may even suppress gravitational wave production at lower frequencies in the pulsar timing band.

Recent analysis of the DESI Collaboration challenges the $\Lambda$-Cold Dark Matter ($\Lambda$CDM) model, suggesting evidence for a dynamic dark energy. These results are obtained in the context of generic parameterizations of the dark energy equation of state (EoS), which better fit the data when they exhibit an unphysical phantom behavior in the past. In this paper, we briefly analyze how ambiguous this latter conclusion can be in light of the background degeneracy between EoS parameterizations and minimally coupled quintessence scenarios. We then investigate whether the current observational data can be accommodated with a non-phantom, thawing dark energy EoS, typical of a broad class of quintessence models. We show that the thawing behavior of this EoS outperforms the CPL parameterization and is statistically competitive with $\Lambda$CDM while predicting cosmic acceleration as a transient phenomenon. Such a dynamic behavior aligns with theoretical arguments from string theory and offers a way out of the trans-Planckian problem that challenges the ever-accelerated $\Lambda$CDM paradigm.

We build slowly rotating anisotropic neutron stars using the Hartle-Thorne formalism, employing three distinct anisotropy models--Horvat, Bowers-Liang, and a covariant model--to characterize the relationship between radial and tangential pressure. We analyze how anisotropy influences stellar properties such as the mass-radius relation, angular momentum, moment of inertia, and binding energy. Our findings reveal that the maximum stable mass of non-rotating stars depends strongly on the anisotropy model, with some configurations supporting up to 60% more mass than their isotropic counterparts with the same central density. This mass increase is most pronounced in the models where the anisotropy grows toward the star's surface, as seen in the covariant model. Furthermore, slowly rotating anisotropic stars adhere to universal relations for the moment of inertia and binding energy, regardless of the chosen anisotropy model or equation of state.

The black hole at the center of M87 is observed to flare regularly in the very high energy (VHE) band, with photon energies $\gtrsim 100$ GeV. The rapid variability, which can be as short as $2$ days in the VHE lightcurve constrains some of the flares to originate close to the black hole. Magnetic reconnection is a promising candidate for explaining the flares, where the VHE emission comes from background soft photons that Inverse Compton (IC) scatter off of high energy electron-positron pairs in the reconnecting current sheet. In this work, we ray trace photons from a current sheet near the black hole event horizon during a flux eruption in a magnetically arrested state in a general relativistic magnetohydrodynamics simulation. We incorporate beaming of the Compton up-scattered photons, based on results from radiative kinetic simulations of relativistic reconnection. We then construct VHE lightcurves that account for the dynamics of the current sheet and lensing from general-relativistic effects. We find that most of the flux originates in the inner $5$ gravitational radii, and beaming is essential to explain the observed flux from the strongest VHE flares. The ray traced lightcurves show features resulting from the changing volume of the reconnecting current sheet on timescales that can be consistent with observations. Furthermore, we find that the amount of beaming depends strongly on two effects: the current sheet inclination with respect to the observer and the anisotropy in the direction of motion of the accelerated particles.

We describe the CHIME All-sky Multiday Pulsar Stacking Search (CHAMPSS) project. This novel radio pulsar survey revisits the full Northern Sky daily, offering unprecedented opportunity to detect highly intermittent pulsars, as well as faint sources via long-term data stacking. CHAMPSS uses the CHIME/FRB datastream, which consists of 1024 stationary beams streaming intensity data at $0.983$\,ms resolution, 16384 frequency channels across 400--800\,MHz, continuously being searched for single, dispersed bursts/pulses. In CHAMPSS, data from adjacent east-west beams are combined to form a grid of tracking beams, allowing longer exposures at fixed positions. These tracking beams are dedispersed to many trial dispersion measures (DM) to a maximum DM beyond the Milky Way's expected contribution, and Fourier transformed in time to form power spectra. Repeated observations are searched daily to find intermittent sources, and power spectra of the same sky positions are incoherently stacked, increasing sensitivity to faint persistent sources. The $0.983$\,ms time resolution limits our sensitivity to millisecond pulsars; we have full sensitivity to pulsars with $P > 60\,$ms, with sensitivity gradually decreasing from $60$ ms to $2$\,ms as higher harmonics are beyond the Nyquist limit. In a commissioning survey, data covering $\sim 1/16$ of the CHIME sky was processed and searched in quasi-realtime over two months, leading to the discovery of eleven new pulsars, each with $S_{600} > 0.1$\,mJy. When operating at scale, CHAMPSS will stack $>$1\,year of data along each sightline, reaching a sensitivity of $\lesssim 30\, \mu$Jy for all sightlines above a declination of $10^{\circ}$, and off of the Galactic plane.

The low-mass end of low-mass galaxies is largely unexplored in AGN studies, but it is essential for extending our understanding of the black hole-galaxy coevolution. We surveyed the 3D-HST catalog and collected a sample of 546 dwarf galaxies with stellar masses log(M$_*$/\(M_\odot\))$<$8.7, residing in the GOODS-South deep field. We then used the unprecedented depth of Chandra available in the GOODS-South field to search for AGN. We carefully investigated the factors that could play roles in the AGN detectability, such as Chandra's point-spread function and the redshift- and off-axis-dependent detection limits. We identified 16 X-ray sources that are likely associated with AGN activity. Next, we evaluated the environment density of each galaxy by computing tidal indices. We uncovered a dramatic impact of the environment on AGN triggering as dwarfs from high-density environments showed an AGN fraction of 22.5\%, while the median stellar mass of this subset of dwarfs is only log(M$_*$/\(M_\odot\))=8.1. In contrast, the low-density environment dwarfs showed an AGN fraction of only 1.4\%, in line with typically reported values from the literature. This highlights the fact that massive central black holes are ubiquitous even at the lowest mass scales and demonstrates the importance of the environment in triggering black hole accretion, as well as the necessity for deep X-ray data and proper evaluation of the X-ray data quality. Alternatively, even if the detected X-ray sources are related to stellar mass accretors rather than AGN, the environmental dependence persists, signaling the impact of the environment on galaxy evolution and star formation processes at the lowest mass scales. Additionally, we stacked the X-ray images of non-detected galaxies from high- and low-density environments, revealing similar trends.

Imaging reconstruction of interferometric data is a hard ill-posed inverse problem. Its difficulty is increased when observing the Galactic Center, which is obscured by a scattering screen. This is because the scattering breaks the one-to-one correspondence between images and visibilities. Solving the scattering problem is one of the biggest challenges in radio imaging of the Galactic Center. In this work we present a novel strategy to mitigate its effect and constrain the screen itself using multiobjective optimization. We exploit the potential of evolutionary algorithms to describe the optimization landscape to recover the intrinsic source structure and the scattering screen affecting the data. We successfully recover both the screen and the source in a wide range of simulated cases, including the speed of a moving screen at 230 GHz. Particularly, we can recover a ring structure in scattered data at 86 GHz. Our analysis demonstrates the huge potential that recent advancements in imaging and optimization algorithms offer to recover image structures, even in weakly constrained and degenerated, possibly multi-modal settings. The successful reconstruction of the scattering screen opens the window to event horizon scale works on the Galactic Center at 86G Hz up to 116 GHz, and the study of the scattering screen itself.

Gravitationally lensed quasars offer a unique opportunity to study cosmological and extragalactic phenomena, using reliable light curves of the lensed images. This requires accurate deblending of the quasar images, which is not trivial due to the small separation between the lensed images (typically $\sim1$ arcsec) and because there is light contamination by the lensing galaxy and the quasar host galaxy. We propose a series of experiments aimed at testing our ability to extract precise and accurate photometry of lensed quasars. In this first paper, we focus on evaluating our ability to extract light curves from simulated CCD images of lensed quasars spanning a broad range of configurations and assuming different observational/instrumental conditions. Specifically, the experiment proposes to go from pixels to light curves and to evaluate the limits of current photometric algorithms. Our experiment has several steps, from data with known point spread function (PSF), to an unknown spatially-variable PSF field that the user has to take into account. This paper is the release of our simulated images. Anyone can extract the light curves and submit their results by the deadline. These will be evaluated with the metrics described below. Our set of simulations will be public and it is meant to be a benchmark for time-domain surveys like Rubin-LSST or other follow-up time-domain observations at higher temporal cadence. It is also meant to be a test set to help develop new algorithms in the future.

Context: Dimethyl sulfide (DMS; CH$_3$SCH$_3$) is an organosulfur compound that has been suggested as a potential biosignature in exoplanetary atmospheres. In addition to its tentative detections toward the sub-Neptune planet K2-18b, DMS has been detected in the coma of the 67/P comet and toward the galactic center molecular cloud G+0.693-0.027. However, its formation routes have not been characterized yet. Aims: In this work, we have investigated three gas-phase reactions (CH$_3$SH + CH$_3$OH$_2^+$, CH$_3$OH + CH$_3$SH$_2^+$, and the CH$_3$ + CH$_3$S radiative association), aiming at characterizing DMS formation routes in shocked molecular clouds and star-forming regions. Methods: We have performed dedicated quantum and kinetics calculations to evaluate the reaction rate coefficients as a function of temperature to be included in astrochemical models. Results: Among the investigated processes, the reaction between methanethiol (CH$_3$SH) and protonated methanol (CH$_3$OH$_2^+$)(possibly followed by a gentle proton transfer to ammonia) is a compelling candidate to explain the formation of DMS in the galactic center molecular cloud G+0.693-0.027. The CH$_3$ + CH$_3$S radiative association does not seem to be a very efficient process, with the exclusion of cold clouds, provided that the thiomethoxy radical (CH$_3$S) is available. This work does not deal directly with the possible formation of DMS in the atmosphere of exoplanets. However, it clearly indicates that there are efficient abiotic formation routes of this interesting species.

Sagittarius A* (Sgr A*) exhibits frequent flaring activity across the electromagnetic spectrum, often associated with a localized region of strong emission, known as a hot spot. We aim to establish an empirical relationship linking key parameters of this phenomenon -- emission radius, inclination, and black hole spin -- to the observed angle difference between the primary and secondary image ($\Delta PA$) that an interferometric array could resolve. Using the numerical radiative transfer code IPOLE, we generated a library of more than 900 models with varying system parameters and computed the position angle difference on the sky between the primary and secondary images of the hot spot. We find that the average $\Delta PA$ over a full period is insensitive to inclination. This result significantly simplifies potential spin measurements which might otherwise have large dependencies on inclination. Additionally, we derive a relation connecting spin to $\Delta PA$, given the period and emission radius of the hot spot, with an accuracy of less than $5^\circ$ in most cases. Finally, we present a mock observation to showcase the potential of this relation for spin inference. Our results provide a novel approach for black hole spin measurements using high-resolution observations, such as future movies of Sgr A* obtained with the Event Horizon Telescope, next-generation Event Horizon Telescope, and Black Hole Explorer.

We predict the sensitivity of the Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST) to faint, resolved Milky Way satellite galaxies and outer-halo star clusters. We characterize the expected sensitivity using simulated LSST data from the LSST Dark Energy Science Collaboration (DESC) Data Challenge 2 (DC2) accessed and analyzed with the Rubin Science Platform as part of the Rubin Early Science Program. We simulate resolved stellar populations of Milky Way satellite galaxies and outer-halo star clusters over a wide range of sizes, luminosities, and heliocentric distances, which are broadly consistent with expectations for the Milky Way satellite system. We inject simulated stars into the DC2 catalog with realistic photometric uncertainties and star/galaxy separation derived from the DC2 data itself. We assess the probability that each simulated system would be detected by LSST using a conventional isochrone matched-filter technique. We find that assuming perfect star/galaxy separation enables the detection of resolved stellar systems with $M_V$ = 0 mag and $r_{1/2}$ = 10 pc with >50% efficiency out to a heliocentric distance of ~250 kpc. Similar detection efficiency is possible with a simple star/galaxy separation criterion based on measured quantities, although the false positive rate is higher due to leakage of background galaxies into the stellar sample. When assuming perfect star/galaxy classification and a model for the galaxy-halo connection fit to current data, we predict that 89 +/- 20 Milky Way satellite galaxies will be detectable with a simple matched-filter algorithm applied to the LSST wide-fast-deep data set. Different assumptions about the performance of star/galaxy classification efficiency can decrease this estimate by ~75-25%, which emphasizes the importance of high-quality star/galaxy separation for studies of the Milky Way satellite population with LSST.

In theories of ultralight dark matter, solitons form in the inner regions of galactic halos. The observational implications of these depend on the soliton mass. Various relations between the mass of the soliton and properties of the halo have been proposed. We analyze the implications of these relations, and test them with a suite of numerical simulations. The relation of Schive et al. 2014 is equivalent to $(E/M)_{\rm sol}=(E/M)_{\rm halo}$ where $E_{\rm sol (halo)}$ and $M_{\rm sol (halo)}$ are the energy and mass of the soliton (halo). If the halo is approximately virialized, this relation is parametrically similar to the evaporation/growth threshold of Chan et al. 2022, and it thus gives a rough lower bound on the soliton mass. A different relation has been proposed by Mocz et al. 2017, which is equivalent to $E_{\rm sol}=E_{\rm halo}$, so is an upper bound on the soliton mass provided the halo energy can be estimated reliably. Our simulations provide evidence for this picture, and are in broad consistency with the literature, in particular after accounting for ambiguities in the definition of $E_{\rm halo}$ at finite volume.

We use the TRAPPIST-1 system as a model observation of Earth-like planets. The densities of these planets being 1-10% less than the Earth suggest that the outer planets may host significant hydrospheres. We explore the uncertainty in water mass fraction from observed mass and radius. We investigate the interior structure of TRAPPIST-1 f using the open-source solver MAGRATHEA and varying assumptions in the interior model. We find that TRAPPIST-1 f likely has a water mass fraction of 16.2% $\pm$ 9.9% when considering all possible core mass fractions and requires 6.9% $\pm$ 2.0% water at an Earth-like mantle to core ratio. We quantify uncertainties from observational precision, model assumptions, and experimental and theoretical data on the bulk modulus of planet building materials. We show that observational uncertainties are smaller than model assumptions of mantle mineralogy and core composition but larger than hydrosphere, temperature, and equation of state assumptions/uncertainties. Our findings show that while precise mass and radius measurements are crucial, uncertainties in planetary models can often outweigh those from observations, emphasizing the importance of refining both theoretical models and experimental data to better understand exoplanet interiors.

We investigate the impact of satellites, a potentially important contributor towards the cold gas assembly of a halo, on the cold gas budgets of 197 TNG50 simulated halos with masses of 10$^{10.85}$ $\le$ M$_{200c}$/M$_{\odot}$ $\le$ 10$^{12.24}$ at $z$ = 0. To highlight the effect of satellites, we split the sample into three mass bins. We find that the total number of satellites, total mass of satellites, number of massive satellites and stellar mass of the most massive satellite, all correlate with the cold gas mass in halos. The total number of satellites (stellar mass of the most massive satellite) correlates most with the halo cold gas mass for low (middle) mass halos. The number of massive or observable satellites correlates with cold gas mass in similar manner as the total number of satellites. Our findings can, therefore, be used to guide future observers to focus on the link between the number of observable satellites and the amount of cold gas in a halo. Despite this correlation, we find that much of the cold gas lies far from the satellites. This leads us to conclude that satellites are unlikely to be the main supplier for cold gas in halos, however we discuss how they may act in tandem with other sources such that the satellite population correlates with the total cold gas in their host halo.

We present a multiwavelength analysis of the galaxy cluster Abell 795 (z=0.1374), known for its extended (200 kpc) radio emission with a steep spectral index of unclear origin surrounding the brightest cluster galaxy (BCG), and for sloshing features observed by Chandra. We used new JVLA 1.5 GHz, archival GMRT 325 MHz, and XMM-Newton data to investigate the nature of the radio emission and the dynamical state of the intracluster medium. Our X-ray surface brightness analysis revealed an azimuthally asymmetric excess extending to 650 kpc from the center, possibly related to the sloshing spiral, although the existing data did not allow us to confirm the presence of a cold front. We also detected a previously unknown galaxy group located 1 Mpc northwest of the cluster. Its X-ray emission was well fitted by a $\beta$-model ($\beta$=0.52$\pm$0.17), and the spectral analysis revealed a thermal plasma temperature kT=1.08$\pm$0.08 keV and metallicity Z=0.13$\pm$0.06 Z$_{\odot}$. We investigated the possibility that this group acted as the perturber that triggered the sloshing in Abell 795, and we showed that the velocity distribution of member galaxies supports the dynamically unrelaxed nature of Abell 795. The analysis of JVLA 1.5 GHz and GMRT 325 MHz images confirmed the presence of extended radio emission with largest linear size 200 kpc, preferentially extended toward southwest and terminating in a sub-component ("SW blob"). We measured the spectral indices, finding $\alpha_{Ext}$=-2.24$\pm$0.13 for the diffuse extended emission, and $\alpha_{SWb}$=-2.10$\pm$0.13 for the SW blob. These ultra-steep spectral index values, coupled with the complex morphology and cospatiality with the radio-loud AGN present in the BCG, suggest that this emission could be classified as a radio phoenix, possibly arising from adiabatic compression of an ancient AGN radio lobe due to the presence of sloshing motions.

We observed the dynamically similar near-Sun asteroids 2021 PH27 and 2025 GN1 for their optical colors. These objects have the lowest known semi-major axes of any asteroids. 2021 PH27 has the largest general relativistic effects of any known solar system object. The small semi-major axis and very close passage to the Sun suggests the extreme thermal and gravitational environment should highly modify these asteroids' surfaces. From g', r', i' and z'-band imaging, we find the colors of 2021 PH27 to be between the two major asteroid types the S and C classes (g'-r'= 0.58 +- 0.02, r'-i'=0.12 +- 0.02 and i'-z'=-0.08 +- 0.05 mags). With a spectral slope of 6.8 +-0.03 percent per 100nm, 2021 PH27 is a X-type asteroid and requires albedo or spectral features to further identify its composition. We find the dynamically similar 2025 GN1 also has very similar colors (g'-r'=0.55 +-0.06 and r'-i'=0.14 +-0.04) as 2021 PH27, suggesting these objects are fragments from a once larger parent asteroid or 2021 PH27 is shedding material. The colors are not blue like some other near-Sun asteroids such as 3200 Phaethon that have been interpreted to be from the loss of reddening substances from the extreme temperatures. There is no evidence of activity or a large amplitude period for 2021 PH27, whereas 2025 GN1 might have a more significant rotational light curve. 2025 GN1 may have a very close encounter or hit Venus in about 2155 years and likely separated from 2021 PH27 in about the last 10 kyrs.

In this paper, we present a homogeneous analysis of close-in Neptune planets. To do this, we compile a sample of TESS-observed planets using a ranking criterion which takes into account the planet's period, radius, and the visual magnitude of its host star. We use archival and new HARPS data to ensure every target in this sample has precise radial velocities. This yields a total of 64 targets, 46 of which are confirmed planets and 18 of which show no significant radial velocity signal. We explore the mass-radius distribution, planetary density, stellar host metallicity, and stellar and planetary companions of our targets. We find 26$\%$ of our sample are in multi-planet systems, which are typically seen for planets located near the lower edge of the Neptunian desert. We define a 'gold' subset of our sample consisting of 33 confirmed planets with planetary radii between 2$R_{\oplus}$ and 10$R_{\oplus}$. With these targets, we calculate envelope mass fractions (EMF) using the GAS gianT modeL for Interiors (GASTLI). We find a clear split in EMF between planets with equilibrium temperatures below and above 1300~K, equivalent to an orbital period of $\sim$3.5~days. Below this period, EMFs are consistent with zero, while above they typically range from 20$\%$ to 40$\%$, scaling linearly with the planetary mass. The orbital period separating these two populations coincides with the transition between the Neptunian desert and the recently identified Neptunian ridge, further suggesting that different formation and/or evolution mechanisms are at play for Neptune planets across different close-in orbital regions.

The LMC's stellar bar is offset from the outer disk center, tilted from the disk plane, and does not drive gas inflows. These properties are atypical of bars in gas-rich galaxies, yet the LMC bar's strength and radius are similar to typical barred galaxies. Using N-body hydrodynamic simulations, we show that the LMC's unusual bar is explainable if there was a recent (${\approx}$100 Myr ago) collision (impact parameter $\approx$2 kpc) between the LMC and SMC. Pre-collision, the simulated bar is centered, co-planar, and has a gaseous counterpart. Post-collision, the simulated bar is offset ($\approx$1.5 kpc), tilted ($\approx8.6^\circ$), and non-existent in gas. The simulated bar offset reduces with time, and comparing with the observed offset ($\approx0.8$ kpc) suggests the timing of the true collision to be 150-200 Myr ago. 150 Myr post-collision, the LMC's bar is centered with its dark matter halo, whereas the outer disk center is separated from the dark matter center by $\approx1$ kpc. The SMC collision produces a tilted-ring morphology for the simulated LMC, consistent with observations. Post-collision, the simulated bar's pattern speed decreases by a factor of two. Hence, observations of the LMC bar pattern speed should be interpreted with caution. We demonstrate that the SMC's torques on the LMC's bar during the collision are sufficient to explain the observed bar tilt, provided the SMC's total mass within 2 kpc was $(0.8-2.4) \times 10^9$ M$_\odot$. Therefore, the LMC bar's tilt constrains the SMC's pre-collision dark matter profile, and requires the SMC to be a dark matter-dominated galaxy.

The vast majority of binary systems are disrupted at the moment of the first supernova, resulting in an unbound compact object and companion star. These ejected companion stars contribute to the observed population of runaway stars. Therefore, an understanding of their ejection velocities is essential to interpreting observations, particularly in the Gaia era of high-precision astronomy. We present a comparison of the predicted ejection velocities of disrupted binary companions in three different population synthesis codes: COSMIC, COMPAS, and binary_c, which use two independent algorithms for the treatment of natal kicks. We confirm that, despite the codes producing different pre-supernova evolution from the same initial conditions, they each find the ejection velocities of secondary stars from disrupted binaries are narrowly distributed about their pre-supernova orbital velocity. We additionally include a correction to the derivation included in Kiel & Hurley 2009 that brings it into agreement with methods from other works for determining post-supernova binary orbital parameters. During this comparison, we identified and resolved bugs in the kick prescriptions of \textit{all three} codes we considered, highlighting how open-science practices and code comparisons are essential for addressing implementation issues.

The Perseus complex offers an ideal testbed to study cluster formation and early evolution as it hosts two major hierarchical structures (namely LISCA I and LISCA II) and the W3/W4/W5 (W345) region characterized by recent star formation. This work aims to provide a full characterization of the population of star clusters in the W345 region, in terms of their structural, photometric, and kinematic properties. Clusters are then used to probe the dynamical properties of the W345 region and, on a larger scale, to investigate the evolution of the Perseus complex. We used Gaia DR3 data to search for star clusters in the W345 region and characterize them in terms of their density structure, ellipticity, internal dynamical state, and ages. We identified five stellar clusters belonging to the W345 complex. The three younger clusters are still partially embedded in the gas and show evidence of expansion, while the older ones cleared the surrounding gas. We also found that YSOs trace the parent gas structure and possibly its kinematics. Thanks to the 6D information available for star clusters, we followed their orbital evolution to assess the formation conditions and evolution of the complex. When accounting for the Galactic potential, we find that the Perseus complex is not dispersing. The observed expansion might be a projection effect due to stars orbiting the Galaxy at different velocities. In addition, we find that the LISCA I and W345 systems formed some $20-30$ Myr ago just a few hundred parsecs away, while LISCA II was originally $\simeq 0.75-1$ kpc apart. Finally, we also assessed the impact of spiral arm perturbations by constructing tailored Galactic potential which matches the observed Galactic spiral arm structure. We find spiral structures drag star clusters toward higher-density regions, possibly keeping clusters closer for longer than the unperturbed, axisymmetric case.

Observations with modern radio interferometers are uncovering the intricate morphology of synchrotron sources in galaxy clusters, both those arising from the intracluster medium (ICM) and those associated with member galaxies. Moreover, in addition to the well-known radio tails from active galactic nuclei, radio continuum tails from jellyfish galaxies are being efficiently detected in nearby clusters and groups. Our goal is to investigate the radio emission from the Ophiuchus cluster, a massive, sloshing cluster in the local Universe ($z=0.0296$) that hosts a diffuse mini halo at its center. To achieve this, we analyzed a 7.25 h MeerKAT L-band observation, producing sensitive images at 1.28 GHz with multiple resolutions. A catalog of spectroscopically confirmed cluster galaxies was used to identify and study the member galaxies detected in radio. We discover thin threads of synchrotron emission embedded in the mini halo, two of which may be connected to the brightest cluster galaxy. We also report the first identification of jellyfish galaxies in Ophiuchus, detecting six galaxies with radio continuum tails, one of which extending for $\sim$64 kpc at 1.28 GHz, making it one of the longest detected at such a high frequency. Finally, we propose an alternative scenario to explain the origin of a bright amorphous radio source, previously classified as a radio phoenix, aided by the comparison with recent simulations of radio jets undergoing kink instability. In Ophiuchus thin threads have been observed within the diffuse emission; a similar result was obtained in Perseus, another nearby cluster hosting a mini halo, suggesting that these structures may be a common feature in this kind of sources. Moreover, radio continuum observations have proven effective in detecting the first jellyfish galaxies in both systems.

Axion quark nuggets (AQNs) are hypothetical objects with nuclear density that would have formed during the quark-hadron transition and could make up most of the dark matter today. These objects have a mass greater than a few grams and are sub-micrometer in size. They would also help explain the matter-antimatter asymmetry and the similarity between visible and dark components of the universe, i.e. $\Omega_{\text{DM}} \sim \Omega_{\text{visible}}$. These composite objects behave as cold dark matter, interacting with ordinary matter and producing pervasive electromagnetic radiation. This work aims to calculate the FUV electromagnetic signature in a 1 kpc region surrounding the solar system, resulting from the interaction between antimatter AQNs and baryons. To this end, we use the high-resolution hydrodynamic simulation of the Milky Way, FIRE-2 Latter suite, to select solar system-like regions. From the simulated gas and dark matter distributions in these regions, we calculate the FUV background radiation generated by the AQN model. We find that the results are consistent with the FUV excess recently confirmed by the Alice spectrograph aboard New Horizons, which corroborated the FUV excess initially discovered by GALEX a decade ago. We also discuss the potential cosmological implications of our work, which suggest the existence of a new source of FUV radiation in galaxies, linked to the interaction between dark matter and baryons.

We propose a GeV-scale self-interacting dark matter (SIDM) candidate within a dark $U(1)_D$ gauged extension of the Standard Model (SM), addressing small-scale structure issues in $\Lambda$CDM while predicting an observable contribution to $\Delta N_{\rm eff}$ in the form of dark radiation. The model introduces a fermionic DM candidate $\chi$ and a scalar $\phi$, both charged under an unbroken $U(1)_D$ gauge symmetry. The self-interactions of $\chi$ are mediated by a light vector boson $X^\mu$, whose mass is generated via the Stueckelberg mechanism. The relic abundance of $\chi$ is determined by thermal freeze-out through annihilations into $X^\mu$, supplemented by a non-thermal component from the late decay of $\phi$. Crucially, $\phi$ decays after the Big Bang Nucleosynthesis (BBN) but before the Cosmic Microwave Background (CMB) epoch, producing additional $\chi$ and a dark radiation species ($\nu_S$). This late-time production compensates for thermal underabundance due to efficient annihilation into light mediators, while remaining consistent with structure formation constraints. The accompanying dark radiation yields a detectable $\Delta N_{\rm eff}$, compatible with Planck 2018 bounds and within reach of next-generation experiments such as SPT-3G, CMB-S4, and CMB-HD.

We explore the gravitational baryogenesis paradigm in the homogeneous and isotropic cosmology of generalized coupling gravity and, in particular, of the so-called Minimal Exponential Measure Model (MEMe). We show that, also in this theory, the time derivative of the Ricci scalar couples with matter currents and can preserve an unbalance in the baryon-antibaryon number beyond thermal equilibrium. Using the current bounds on the ratio of baryon number to entropy density, we can considerably improve the known constraints on the parameter q that characterizes the MEMe model. This estimate also allows us to draw stringent constraints on the spatial curvature of the cosmological model.

We investigate the capability of the Taiji space-based gravitational wave observatory to detect stochastic gravitational wave backgrounds produced by first-order phase transitions in the early universe. Using a comprehensive simulation framework that incorporates realistic instrumental noise, galactic double white dwarf confusion noise, and extragalactic compact binary backgrounds, we systematically analyze Taiji's sensitivity across a range of signal parameters. Our Bayesian analysis demonstrates that Taiji can robustly detect and characterize phase transition signals with energy densities exceeding $\Omega_{\text{PT}} \gtrsim 1.4 \times 10^{-11}$ across most of its frequency band, with particularly strong sensitivity around $10^{-3}$ to $10^{-2}$ Hz. For signals with amplitudes above $\Omega_{\text{PT}} \gtrsim 1.1 \times 10^{-10}$, Taiji can determine the peak frequency with relative precision better than $10\%$. These detection capabilities would enable Taiji to probe electroweak-scale phase transitions in various beyond-Standard-Model scenarios, potentially revealing new physics connected to baryogenesis and dark matter production. We quantify detection confidence using both Bayes factors and the Deviance Information Criterion, finding consistent results that validate our statistical methodology.

A relativistic self-gravitating equilibrium system with steady flow as well as spherical symmetry is discovered. The energy-momentum tensor contains the contribution of a current related to the flow and the metric tensor does an off-diagonal component to balance with the flow momentum. The presence of the off-diagonal component of the metric implies the radial motion of the reference frame, which gives rise to a problem how the relativistic effect is included in thermodynamic observables for such a general relativistic system. This problem is solved by taking an instantaneously rest frame in which geometric thermodynamic observables read as previously and giving them the special relativistic effect emerged from the inverse transformation to the original frame pointwise. The solution of the thermodynamic observables in accord with the laws of thermodynamics and the theory of relativity is presented. Finally the relativistic structure equations for the equilibrium are derived, from which the general relativistic Poisson equation as well as the heat conduction one are developed exactly.

We explore the quantum state transition of photon orbital angular momentum (OAM) in the present of gravitational waves (GWs) and demonstrate the potential of a new photonic single-arm GW detection technique. The interaction is calculated based on the framework of the wave propagation in linearized gravity theory and canonical quantization of the electromagnetic field in curved spacetime. It is demonstrated that when a photon possessing OAM of 1 interacts with GWs, it may relinquish its OAM and produce a central signal that may be detected. The detector provides a high and steady rate of detected photons in the low-frequency range ($<1$ Hz), opens a potential window to identify GWs in the mid-frequency range ($1\sim10$ Hz), which is absent in other contemporary GW detectors, and establishes a selection rule for GW frequencies in the high-frequency range ($>10$ Hz), allowing for the adjustment of detector parameters to focus on specific GW frequencies. Furthermore, the detector is insensitive to seismic noise, and the detectable photon count rate is proportional to the square of the GW amplitude, making it more advantageous for determining the distance of the source compared to current interferometer detectors. This technique not only facilitates the extraction of GW information but also creates a new approach for identifying and selecting GW signals.

One of the key scientific objectives for the next decade is to uncover the nature of dark matter (DM). We should continue prioritizing targets such as weakly-interacting massive particles (WIMPs), Axions, and other low-mass dark matter candidates to improve our chances of achieving it. A varied and ongoing portfolio of experiments spanning different scales and detection methods is essential to maximize our chances of discovering its composition. This report paper provides an updated overview of the Brazilian community's activities in dark matter and dark sector physics over the past years with a view for the future. It underscores the ongoing need for financial support for Brazilian groups actively engaged in experimental research to sustain the Brazilian involvement in the global search for dark matter particles

An understanding of how turbulent energy is partitioned between ions and electrons in weakly collisional plasmas is crucial for modelling many astrophysical systems. Using theory and simulations of a four-dimensional reduced model of low-beta gyrokinetics (the 'Kinetic Reduced Electron Heating Model'), we investigate the dependence of collisionless heating processes on plasma beta and imbalance (normalised cross-helicity). These parameters are important because they control the helicity barrier, the formation of which divides the parameter space into two distinct regimes with remarkably different properties. In the first, at lower beta and/or imbalance, the absence of a helicity barrier allows the cascade of injected power to proceed to small (perpendicular) scales, but its slow cascade rate makes it susceptible to significant electron Landau damping, in some cases leading to a marked steepening of the magnetic spectra on scales above the ion Larmor radius. In the second, at higher beta and/or imbalance, the helicity barrier halts the cascade, confining electron Landau damping to scales above the steep 'transition-range' spectral break, resulting in dominant ion heating. We formulate quantitative models of these processes that compare well to simulations in each regime, and combine them with results of previous studies to construct a simple formula for the electron-ion heating ratio as a function of beta and imbalance. This model predicts a 'winner takes all' picture of low-beta plasma heating, where a small change in the fluctuations' properties at large scales (the imbalance) can cause a sudden switch between electron and ion heating.

We study a point scalar charge in circular orbit around a topological star, a regular, horizonless soliton emerging from dimensional compactification of Einstein-Maxwell theory in five dimensions, which could describe qualitative properties of microstate geometries for astrophysical black holes. This is the first step towards studying extreme mass-ratio inspirals around these objects. We show that when the particle probes the spacetime close to the object, the scalar-wave flux deviates significantly from the corresponding black hole case. Furthermore, as the topological star approaches the black-hole limit, the inspiral can resonantly excite its long-lived modes, resulting in sharp features in the emitted flux. Although such resonances are too narrow to produce detectable dephasing, we estimate that a year-long inspiral down to the innermost stable circular orbit could accumulate a significant dephasing for most configurations relative to the black hole case. While a full parameter-estimation analysis is needed, the generically large deviations are likely to be within the sensitivity reach of future space-based gravitational-wave detectors.

We present estimators for quantifying intrinsic alignments in large spectroscopic surveys that efficiently capture line-of-sight (LOS) information while being relatively insensitive to redshift-space distortions (RSD). We demonstrate that changing the LOS integration range, {\Pi}max, as a function of transverse separation outperforms the conventional choice of a single {\Pi}max value. This is further improved by replacing the flat {\Pi}max cut with a LOS weighting based on shape projection and RSD. Although these estimators incorporate additional LOS information, they are projected correlations that exhibit signal-to-noise ratios comparable to 3D correlation functions, such as the IA quadrupole. Using simulations from Abacus Summit, we evaluate these estimators and provide recommended {\Pi}max values and weights for projected separations of 1 - 100 Mpc/h. These will improve measurements of intrinsic alignments in large cosmological surveys and the constraints they provide for both weak lensing and direct cosmological applications.

We show that the regularization of the second order pole in the pole inflation can induce the increase of $n_s$, which may be important after the latest data release of cosmic microwave background (CMB) observation by Atacama Cosmology Telescope (ACT). Pole inflation is known to provide a unified description of attractor models that they can generate a flat plateau for inflation given a general potential. Recent ACT observation suggests that the constraint on the scalar spectral index $n_s$ at CMB scale may be shifted to a larger value than the predictions in the Starobinsky model, the Higgs inflation, and the $\alpha$-attractor model, which motivates us to consider the modification of the pole inflation. We find that if we regularize the second order pole in the kinetic term such that the kinetic term becomes regular for all field range, we can generally increase $n_s$ because the potential in the large field regime will be lifted. We have explicitly demonstrated that this type of regularized pole inflation can naturally arise from the Einstein-Cartan formalism, and the inflationary predictions are consistent with the latest ACT data without spoiling the success of the $\alpha$-attractor models.

The enhanced primordial scalar power spectrum is a widely studied mechanism for generating primordial gravitational waves (PGWs), also referred to as scalar-induced gravitational waves (SIGWs). This process also plays a pivotal role in facilitating the formation of primordial black holes (PBHs). Traditionally, the ultra slow-roll (USR) mechanism has been the predominant approach used in the early universe. In this framework, the second slow-roll parameter $\epsilon_2$, is typically set to $-6$ or lower for a brief period -- marking a significant departure from the standard slow-roll condition where $\epsilon_2 \simeq 0$. Such conditions often emerge in models with inflection points or localized features, such as bumps in the potential. In this paper, we challenge the conventional assumption that $\epsilon_2 \lesssim -6$ is a prerequisite for substantial amplification of the scalar power spectrum. We demonstrate that any negative value of the second slow-roll parameter can indeed enhance the scalar power spectrum through sub-horizon growth, establishing this as a necessary and sufficient condition for amplification. Consequently, this mechanism facilitates the generation of both PGWs and PBHs. To illustrate this, we examine a standard scenario where a brief USR phase is embedded between two slow-roll (SR) phases. By systematically varying $\epsilon_{2}$ values from $-1$ to $-10$ in the USR region, we investigate the amplification of the power spectrum and its implications for PGWs and PBHs production, particularly in the context of ongoing and future cosmological missions.

Deconvolution, imaging and calibration of data from radio interferometers is a challenging computational (inverse) problem. The upcoming generation of radio telescopes poses significant challenges to existing, and well proven data reduction pipelines due to the large data sizes expected from these experiments, and the high resolution and dynamic range. In this manuscript, we deal with the deconvolution problem. A variety of multiscalar variants to the classical CLEAN algorithm (the de-facto standard) have been proposed in the past, often outperforming CLEAN at the cost of significantly increasing numerical resources. In this work, we aim to combine some of these ideas for a new algorithm, Autocorr-CLEAN, to accelerate the deconvolution and prepare the data reduction pipelines for the data sizes expected by the upcoming generation of instruments. To this end, we propose to use a cluster of CLEAN components fitted to the autocorrelation function of the residual in a subminor loop, to derive continuously changing, and potentially non-radially symmetric, basis functions for CLEANing the residual. Autocorr-CLEAN allows for the superior reconstruction fidelity achieved by modern multiscalar approaches, and their superior convergence speed. It achieves this without utilizing any substep of super-linear complexity in the minor loops, keeping the single minor loop and subminor loop iterations at an execution time comparable to CLEAN. Combining these advantages, Autocorr-CLEAN is found to be up to a magnitude faster than the classical CLEAN procedure. Autocorr-CLEAN fits well in the algorithmic framework common for radio interferometry, making it relatively straightforward to include in future data reduction pipelines. With its accelerated convergence speed, and smaller residual, Autocorr-CLEAN may be an important asset for the data analysis in the future.

Jets and disc winds play an important role in the evolution of protoplanetary discs and the formation of planetary systems. However, there is still a lack of observational data regarding the presence and parameters of outflows, especially for close young binaries. In this study, we aim to find the HH flow near the young sub-arcsecond binary DF Tau and explore its morphology. Narrow-band H$\alpha$ and H$_2$ 2.12 $\mu$m imaging and spectroscopic observations of DF Tau and its vicinity were performed. We have discovered several emission nebulae near the binary, which likely result from the interaction of gas outflow from the binary components with the surrounding medium. The outflow appears to occur both in the form of jets, generating numerous Herbig-Haro objects (HH 1266 flow), and as a weakly collimated wind responsible for the formation of the ring-like nebula around the binary and the rim of the cometary globule. We have found that the angle between the jet and the counter-jet is $168^\circ$ and discuss the complex morphology of the HH flow.

Tidal disruption events (TDEs) occur when stars pass close enough to supermassive black holes to be torn apart by tidal forces. Traditionally, these events are studied with computationally intensive hydrodynamical simulations. In this paper, we present a fast, physically motivated two-stage model for TDEs. In the first stage, we model the star's tidal deformation using linear stellar perturbation theory, treating the star as a collection of driven harmonic oscillators. When the tidal energy exceeds a fraction $\gamma$ of the star's gravitational binding energy (with $\gamma \sim \mathcal{O}(1)$), we transition to the second stage, where we model the disrupted material as free particles. The parameter $\gamma$ is determined with a one-time calibration to hydrodynamical simulations. This method enables fast computation of the energy distribution $\mathrm{d}M/\mathrm{d}E$ and fallback rate $\mathrm{d}M/\mathrm{d}T$, while offering physical insight into the disruption process. We apply our model to MESA-generated profiles of middle-age main-sequence stars. Our code is available on GitHub.

The detection of the 244 EeV Amaterasu event by the Telescope Array, one of the most energetic ultrahigh-energy cosmic rays (UHECRs; $E\gtrsim0.1$ EeV) observed to date, invites scrutiny of its potential source. We investigate whether the nearby blazar PKS 1717+177, located within $2.5^\circ$ of the reconstructed arrival direction, could explain the event under a proton-primary hypothesis. Using a one-zone jet model, we fit the multi-wavelength spectral energy distribution of the source, incorporating both leptonic and hadronic cascade emission from photohadronic interactions. Our model supports a cosmic-ray origin of the very-high-energy ($E\gtrsim 100$ GeV) $\gamma$-ray flux and predicts a subdominant neutrino flux, an order of magnitude lower than from TXS 0506+056. Under Lorentz invariance violation, protons above a specific energy can propagate over hundreds of Mpc without significant energy loss for certain parameter choices. In such a scenario, our analysis indicates negligible deflection in the Galactic magnetic field, implying a strong extragalactic magnetic field, placing a lower bound on the field strength. Our findings provide a compelling multi-messenger framework linking UHECRs, $\gamma$ rays, and neutrinos and motivate targeted searches by current and future high-energy neutrino telescopes during increased $\gamma$-ray or X-ray activity of this blazar.

QSEBs are small-scale magnetic reconnection events in lower solar atmosphere. Sometimes, they exhibit transition region counterparts, known as UV brightenings. Magnetic field extrapolations suggest that QSEBs can occur at various locations of a fan-spine topology, with UV brightening occurring at null point through a common reconnection process. We aim to understand how complex magnetic configurations like interacting fan-spine topologies can cause small-scale dynamic phenomena in lower atmosphere. QSEBs were detected using k-means clustering on Hbeta observations from Swedish 1-m Solar Telescope (SST). Further, chromospheric inverted-Y-shaped jets were identified in the Hbeta blue wing. Magnetic field topologies were determined through potential field extrapolations from photospheric magnetograms using the Fe I 6173 A line. UV brightenings were detected in IRIS 1400 A SJI. We identify two distinct magnetic configurations associated with QSEBs, UV brightenings, and chromospheric inverted-Y-shaped jets. The first involves a nested fan-spine structure where, due to flux emergence, an inner 3D null forms inside fan surface of an outer 3D null with some overlap. QSEBs occur at two footpoints along the shared fan surface, with UV brightening located near the outer 3D null point. The jet originates close to the two QSEBs and follows the path of high squashing factor Q. We discuss a comparable scenario using a numerical simulation. In second case, two adjacent fan-spine topologies share fan footpoints at a common positive polarity patch, with the QSEB, along with a chromospheric inverted-Y-shaped jet, occurring at the intersection having high Q values. This study demonstrates through observational and modelling support that associated QSEBs, UV brightenings, and chromospheric inverted-Y-shaped jets share a common origin driven by magnetic reconnection between interacting fan-spine topologies.

Type IIn supernovae (SNe) resembling SN 2009ip (09ip-like SNe) originate from the interaction between circumstellar material (CSM) and the ejecta. This subclass not only shares similar observational properties around the maximum, but is commonly characterized by a long duration precursor before its maximum. Investigating the observed properties of the precursor provides constraints on the mass-loss history of the progenitor.We present observational data of SN 2023vbg, a 09ip-like type IIn SN that displayed unique observational properties compared to other 09ip-like SNe. SN 2023vbg showed a long-duration precursor at $M_g\sim-14$ mag lasting for $\sim100$ days, followed by a bright bump at $M_g\sim-17$ mag at 12-25 days before the maximum. The luminosity of the precursor is similar to those of other 09ip-like SNe, but the bright bump has not been observed in other cases.After reaching the peak luminosity, the light curve exhibited a peculiar smooth decline.While the H$\alpha$ profile displays two velocity components ($\sim 500$ and $3000\ \mathrm{km\ s^{-1}}$), a broad component observed in other 09ip-like SNe was not detected. We suggest that these properties are explained by the difference in the CSM structure as compared to other 09ip-like SNe; SN 2023vbg had an inner denser CSM component, as well as generally smooth CSM density distribution in a more extended scale, than in the others. Such diversity of CSM likely reflects the diversity of pre-SN outbursts, which in turn may mirror the range of evolutionary pathways in the final stages of the progenitors.

The CHNOS elemental budgets of rocky planets are crucial for their structure, evolution and potential chemical habitability. It is unclear how the nonlocal disk processes affecting dust in planet-forming disks affect the CHNOS elemental budgets of nascent planets both inside and outside the Solar System. We aim to quantify the coupled effect of dynamical and collisional processes on the initial refractory CHNOS budgets of planetesimals, forming interior to the water ice line for a Solar and non-Solar composition consistent with the star HIP 43393. Methods. We utilize the SHAMPOO code to track the effects of dynamical and collisional processes on 16000 individual dust monomers. Each monomer is here assigned a refractory chemical composition and mineralogy informed by the equilibrium condensation code GGCHEM given the P-T conditions at the initial position of the monomer. Monomers travel embedded in aggregates through a young class I disk, whose structure is calculated with the ProDiMo code. Furthermore, monomers are allowed to undergo dehydration and desulfurization. We find that solid material becomes well-mixed both radially and vertically. For both the Solar and HIP43393 compositions, the solid phase in the disk midplane regions interior to r~0.7AU can become enriched in hydrogen and sulfur by up to 10at% relative to predictions from purely local calculations. This originates from the inward radial transport of hydrated and sulfur-bearing minerals such as lizardite and iron sulfide. Nonlocal disk processing in a young turbulent, massive disk can lead to significant compositional homogenization of the midplane dust and by extension of the initial composition of planetesimals. Planetesimals forming at r<0.7AU may become enriched in hydrated minerals and sulfur, which could result in more widespread aqueous alteration interior to the water iceline compared to planetesimals that emerge...

Long Gamma Ray Bursts (lGRBs) are associated with jets in Type Ic broadline supernovae. The Collapsar model provides a theoretical framework for the jet formation from the core collapse of a massive star in such supernovae. The GRB can only be produced after a successful jet break out from the star. Under this formalism the GRB duration ($t_{\rm{90}}$) has been hypothesized to be the difference between the central engine activity duration ($t_{\rm{eng}}$) and the jet breakout time ($t_{\rm{bo}}$), that is $t_{\rm{90}} = t_{\rm{eng}} - t_{\rm{bo}}$. This disallows $t_{\rm{90}} > t_{\rm{eng}}$ and puts a lower bound on successful lGRB jet central engine duration ($t_{\rm{eng}} > t_{\rm{bo}}$), various numerical simulations have shown otherwise. This study considers a photospheric GRB emission from a relativistic jet punching out of a Wolf-Rayet-like star. We use the bolometric lightcurve generated to calculate the lGRB duration ($t_{\rm{90}}$) for varying engine duration. We find for longer engine duration the lGRB lightcurve reflects the jet profile and $t_{\rm{90}} \approx t_{\rm{eng}}$. While for shorter engine duration, the $t_{\rm{90}}$ has photospheric radius ($R_{\rm{ph}}$) dependence. This can be modeled by a relation, $t_{\rm{90}} = t^{\rm{90}}_{\rm{eng}} + 0.03\left(\frac{R_{\rm{ph}}}{c}\right)$, where c is the speed of light, with a lower bound on $t_{\rm{90}}$ for a successful lGRB. This relation should be most relevant for possible low-luminous lGRBs originating from a collapsar with central engine duration comparable to the jet breakout time.

The infrared (IR) to X-ray luminosity ratio (IRX) is an indicator of the role of the dust plays in cooling of hot gas in supernova remnants (SNR). Using the 3D dynamics of gas and interstellar polydisperse dust grains we analyze the evolution of SNR in the inhomogeneous medium. We obtain spatial distributions of the surface brigthness both of the X-ray emission from hot gas inside SNR and the IR emission from the SNR swept-up shell, as well as, the average gas temperature in the SNR, $T_X$. We find that the IRX changes significantly (by a factor of $\sim 3-30$) as a function of impact distance within the SNR and its age. In a low inhomogeneous medium the IRX drops rapidly during the SNR evolution. On the other hand, if large inhomogeneities are present in the medium, the IRX is maintained at higher levels during the late SNR evolution at radiative phase due to replenishment of dust in the hot gas by incompletely destroyed fragments behind the shock front. We show that the onset of the radiative phase determines the evolution of the $T_X - {\rm IRX}$ diagram. We illustrate that decreasing gas metallicity or density leads to high values of temperature and IRX ratio. We discuss how our results can be applied to the observational data to analyse the SNR older than 10 kyr (i.e. when the mass of the swept-up dust in the shell is expected to exceed that produced in the SNR) in the Galaxy and Large Magellanic Cloud.

Determining the composition of an exoplanet atmosphere relies on the presence of detectable spectral features. The strongest spectral features, including DMS, look approximately Gaussian. Here, I perform a suite of Gaussian feature analyses to find any statistically significant spectral features in the recently published MIRI/LRS spectrum of K2-18b (N. Madhusudhan et al. 2025). In N. Madhusudhan et al. 2025, they claim a 3.4-$\sigma$ detection of spectral features compared to a flat line. In 5 out of 6 tests, I find the data preferred a flat line over a Gaussian model, with a $\chi^{2}_{\nu}$ of 1.06. When centering the Gaussian where the absorptions for DMS and DMDS peak, I find ln(B) = 1.21 in favour of the Gaussian model, with a $\chi^{2}_{\nu}$ of 0.99. With only $\sim$2-$\sigma$ in favour of Gaussian features, I conclude no strong statistical evidence for spectral features.

(Aims) Hot Dust Obscured Galaxies (Hot DOGs) are a population of hyper-luminous, heavily obscured quasars. Although nuclear obscurations close to Compton-thick are typical, a fraction show blue UV spectral energy distributions consistent with unobscured quasar activity, albeit two orders of magnitude fainter than expected from their mid-IR luminosity. The origin of the UV emission in these Blue excess Hot DOGs (BHDs) has been linked to scattered light from the central engine. Here we study the properties of the UV emission in the BHD WISE J020446.13-050640.8 (W0204-0506). (Methods) We use imaging polarization observations in the $R_{\rm Special}$ band obtained with the FORS2 instrument at VLT. We compare these data with radiative transfer simulations to constrain the characteristics of the scattering material. (Results) We find a spatially integrated polarization fraction of $24.7\pm 0.7$%, confirming the scattered-light nature of the UV emission of W0204-0506. The source is spatially resolved in the observations and we find a gradient in polarization fraction and angle that is aligned with the extended morphology of the source found in HST/WFC3 imaging. A dusty, conical polar outflow starting at the AGN sublimation radius with a half-opening angle $\lesssim 50~\rm deg$ viewed at an inclination $\gtrsim 45~\rm deg$ can reproduce the observed polarization fraction if the dust is graphite-rich. We find that the gas mass and outflow velocity are consistent with the range of values found for [OIII] outflows through spectroscopy in other Hot DOGs, though it is unclear whether the outflow is energetic enough to affect the long-term evolution of the host galaxy. Our study highlights the unique potential for polarization imaging to study dusty quasar outflows, providing complementary constraints to those obtained through traditional spectroscopic studies.

We present radial density profiles, as traced by luminous galaxies and dark matter particles, for voids in eleven snapshots of the \texttt{TNG300} simulation. The snapshots span 11.65~Gyr of cosmic time, corresponding to the redshift range $0 \le z \le 3$. Using the comoving galaxy fields, voids were identified via a well-tested, watershed transformation-based algorithm. Voids were defined to be underdense regions that are unlikely to have arisen from Poisson noise, resulting in the selection of $\sim100-200$ of the largest underdense regions in each snapshot. At all redshifts, the radial density profiles as traced by both the galaxies and the dark matter resemble inverse top-hat functions. However, details of the functions (particularly the underdensities of the innermost regions and the overdensities of the ridges) evolve considerably more for the dark matter density profiles than for the galaxy density profiles. At all redshifts, a linear relationship between the galaxy and dark matter density profiles exists, and the slope of the relationship is similar to the bias estimates for \texttt{TNG300} snapshots. Lastly, we identify distinct environments in which voids can exist, defining ''void-in-void" and ''void-in-cloud" populations (i.e., voids that reside in larger underdense or overdense regions, respectively) and we investigate ways in which the relative densities of dark matter and galaxies in the interiors and ridges of these structures vary as a function of void environment.

Neutron stars (NSs) probe the high-density regime of the nuclear equation of state (EOS). However, inferring the EOS from observations of NSs is a computationally challenging task. In this work, we efficiently solve this inverse problem by leveraging differential programming in two ways. First, we enable full Bayesian inference in under one hour of wall time on a GPU by using gradient-based samplers, without requiring pre-trained machine learning emulators. Moreover, we demonstrate efficient scaling to high-dimensional parameter spaces. Second, we introduce a novel gradient-based optimization scheme that recovers the EOS of a given NS mass-radius curve. We demonstrate how our framework can reveal consistencies or tensions between nuclear physics and astrophysics. First, we show how the breakdown density of a metamodel description of the EOS can be determined from NS observations. Second, we demonstrate how degeneracies in EOS modeling using nuclear empirical parameters can influence the inverse problem during gradient-based optimization. Looking ahead, our approach opens up new theoretical studies of the relation between NS properties and the EOS, while effectively tackling the data analysis challenges brought by future detectors.

We search for possible GeV-TeV gamma-ray imprints of ultrahigh-energy (UHE; $\gtrsim 0.1$ EeV) cosmic ray (CR) acceleration in the large-scale structures surrounding the brightest gamma-ray burst (GRB) explosion, GRB 221009A. Using 1.25 years of post-event Fermi Large Area Telescope (LAT) data, we construct a 1 GeV - 1 TeV test-statistic (TS) map within 15 Mpc of the burst. We identify two peaks in the TS map with TS $\geq 9$. The most significant peak, J1911.8+2044, exhibits gamma-ray emission in pre-burst LAT data. The other peak, J1913.2+1901, coincides with a 664.6 GeV photon recorded $\sim191.9$ days after the GRB trigger and located at about $0.75^{\circ}$ from the GRB localization. The per-photon 95% containment angle for the LAT is about $0.25^{\circ}$ in the 100 GeV - 1 TeV energy range. We explore two possible origins for the $\gamma$-ray emission: (1) UHECRs from GRB 221009A propagating through a magnetized cosmological volume in its vicinity, and (2) UHE or very-high-energy (VHE; $\gtrsim 100$ GeV) $\gamma$-ray emission from GRB 221009A, propagating in the same volume. In both cases, electromagnetic cascade emission is induced in the structured region embedding the burst. If any TS features are related to large-scale imprints induced by cosmic rays, it might be further evidence that GRB 221009A accelerated UHECRs. However, our results show that alternative scenarios without invoking UHECRs cannot be ruled out, and the observed high-energy photon could be unrelated to GRB 221009A.

Eclipsing binary systems (EBs), as foundational objects in stellar astrophysics, have garnered significant attention in recent years. These systems exhibit periodic decreases in light intensity when one star obscures the other from the observer's perspective, producing characteristic light curves (LCs). With the advent of the Transiting Exoplanet Survey Satellite (TESS), a vast repository of stellar LCs has become available, offering unprecedented opportunities for discovering new EBs. To efficiently identify such systems, we propose a novel method that combines LC data and generalized Lomb-Scargle periodograms (GLS) data to classify EBs. At the core of this method is CNN Attention LSTM Net (CALNet), a hybrid deep learning model integrating Convolutional Neural Networks (CNNs), Long Short-Term Memory (LSTM) networks, and an Attention Mechanism based on the Convolutional Block Attention Module (CBAM). We collected 4,225 EB samples, utilizing their 2-minute cadence LCs for model training and validation. CALNet achieved a recall rate of 99.1%, demonstrating its robustness and effectiveness. Applying it to TESS 2-minute LCs from Sectors 1 to 74, we identified 9,351 new EBs after manual visual inspection, significantly expanding the known sample size. This work highlights the potential of advanced deep-learning techniques in large-scale astronomical surveys and provides a valuable resource for further studies on EBs.

In recent years, high-precision high-cadence space photometry has revealed that stochastic low frequency (SLF) variability is common in the light curves of massive stars. We use the data from the Transiting Exoplanet Survey Satellite (TESS) to study and characterize the SLF variability found in a sample of 49 O- and B-type main-sequence stars across six Cygnus OB~associations and one low-metallicity SMC star AV~232. We compare these results to 53 previously studied SLF variables. We adopt two different methods for characterizing the signal. In the first, we follow earlier work and fit a Lorentzian-like profile to the power density spectrum of the residual light curve to derive the amplitude $\alpha_0$, characteristic frequency $\nu_{\rm char}$, and slope $\gamma$ of the variability. In our second model-independent method, we calculate the root-mean-square (RMS) of the photometric variability as well as the frequency at 50\% of the accumulated power spectral density, $\nu_{50\%}$, and the width of the cumulative integrated power density, $w$. For the full sample of 103 SLF variables, we find that $\alpha_0$, $\gamma$, RMS, $\nu_{50\%}$, and $w$ correlate with the spectroscopic luminosity of the stars. Both $\alpha_0$ and RMS appear to increase for more evolved stars whereas $\nu_{\rm char}$ and $\nu_{50\%}$ both decrease. Finally, we compare our results to 2-D and 3-D simulations of subsurface convection, core-generated internal gravity waves, and surface stellar winds, and find good agreement between the observed $\nu_{\rm char}$ of our sample and predictions from sub-surface convection.

The evolution of large-scale structure, galaxies and the intergalactic medium (IGM) during the Epoch of Reionization (EoR) can be probed by upcoming Line Intensity Mapping (LIM) experiments, which sample in redshift and direction without needing to resolve individual galaxies. We predict the intensity and sources of hydrogen H$\alpha$ emission, dominated by radiative recombination following ionization by UV from the same massive stars that caused reionization, down to redshift 4.6, using the largest fully-coupled, radiation-hydro simulation of galaxy formation and reionization to date, Cosmic Dawn (CoDa) III. We compute the mean intensity and Voxel Intensity Distribution (VID) vs. redshift, including the relative contributions of galaxies and IGM. This will provide mock data to guide and interpret LIM experiments such as NASA's SPHEREx and proposed Cosmic Dawn Intensity Mapper (CDIM).

Cosmic rays are often modeled as charged particles. This allows their non-ballistic propagation in magnetized structures to be captured. In certain situations, a neutral cosmic ray component can arise. For example, cosmic ray neutrons are produced in considerable numbers through hadronic pp and p$\gamma$ interactions. At ultrahigh energies, the decay timescales of these neutrons is dilated, allowing them to traverse distances on the scale of galactic and cosmological structures. Unlike charged cosmic rays, neutrons are not deflected by magnetic fields. They propagate ballistically at the speed of light in straight lines. The presence of a neutral baryonic cosmic ray component formed in galaxies, clusters and cosmological filaments can facilitate the escape and leakage of cosmic rays from magnetic structures that would otherwise confine them. We show that, by allowing confinement breaking, the formation of cosmic-ray neutrons by high-energy hadronic interactions in large scale astrophysical structures can modify the exchange of ultra high-energy particles across magnetic interfaces between galaxies, clusters, cosmological filaments and voids.

The ultra-hot Jupiter (UHJ) TOI-2109b marks the lower edge of the equilibrium temperature gap between 3500 K and 4500 K, an unexplored thermal regime that separates KELT-9b, the hottest planet yet discovered, from all other currently known gas giants. To study the structure of TOI-2109b's atmosphere, we obtained high-resolution emission spectra of both the planetary day- and nightsides with CARMENES and CRIRES$^+$. By applying the cross-correlation technique, we identified the emission signatures of Fe I and CO, as well as a thermal inversion layer in the dayside atmosphere; no significant H$_2$O signal was detected from the dayside. None of the analyzed species were detectable from the nightside atmosphere. We applied a Bayesian retrieval framework that combines high-resolution spectroscopy with photometric measurements to constrain the dayside atmospheric parameters and derive upper limits for the nightside hemisphere. The dayside thermal inversion extends from 3200 K to 4600 K, with an atmospheric metallicity consistent with that of the host star (0.36 dex). Only weak constraints could be placed on the C/O ratio ($>$ 0.15). The retrieved spectral line broadening is consistent with tidally locked rotation, indicating the absence of strong dynamical processes. An upper temperature limit of 2400 K and a maximum atmospheric temperature gradient of 700 K/log bar could be derived for the nightside. Comparison of the retrieved dayside T-p profile with theoretical models, the absence of strong atmospheric dynamics, and significant differences in the thermal constraints between the day- and nightside hemispheres suggest a limited heat transport efficiency across the planetary atmosphere. Overall, our results place TOI-2109b in a transitional regime between the UHJs below the thermal gap, which show both CO and H$_2$O emission lines, and KELT-9b, where molecular features are largely absent.

SiO masers from AGB stars exhibit variability in intensity and polarization during a pulsation period. This variability is explained by radiative transfer and magnetic properties of the molecule. To investigate this phenomenon, a 3D maser simulation is employed to study the SiO masers based on Zeeman splitting. We demonstrate that the magnetic field direction affects maser polarization within small tubular domains with isotropic pumping, and yields results that are similar to those obtained from 1D modelling. This work also studies larger clouds with different shapes. We use finite-element domains with internal node distributions to represent the maser-supporting clouds. We calculate solutions for the population inversions in all transitions and at every node. These solutions show that saturation begins near the middle of a domain, moving towards the edges and particularly the ends of long axes, as saturation progresses, influencing polarization. When the observer's view of the domain changes, the plane of linear polarization responds to the projected shape and the projected magnetic field axis. The angle between the observer's line of sight and the magnetic field may cause jumps in the plane of polarization. Therefore, we can conclude that polarization is influenced by both the cloud's major axis orientation and magnetic field direction. We have investigated the possibility of explaining observed polarization plane rotations, apparently within a single cloud, by the mechanism of line-of-sight overlap of two magnetized maser clouds.

This paper reports on the detection of a likely explosive outflow in the high-mass star-forming complex G34.26+0.15, adding to the small number (six) of explosive outflows detected so far. ALMA CO(2-1) and SiO(5-4) archival observations reveal multiple outflow streamers from G34.26+0.15, which correlate well with H2 jets identified from Spitzer-IRAC 4.5 um and [4.5]/[3.6] flux ratio maps. These nearly linear outflow streamers originate from a common center within an ultracompact HII region located in the complex. The velocity spread of the outflow streamers ranges from 0 to 120 km/s. The radial velocities of these streamers follow the Hubble-Lema\^itre velocity law, indicating an explosive nature. From the CO emission, the total outflow mass, momentum, and outflow energy are estimated to be ~264 M_sun, 4.3*10^3 M_sun km/s, and 10^48 erg, respectively. The event triggering the outflow may have occurred about 19,000 years ago and could also be responsible for powering the expanding UC HII region, given the similar dynamical ages and positional coincidence of the UC HII region with the origin of the outflow. The magnetic field lines in the region associated with G34.26+0.15 also appear to align with the direction of the outflow streamers and jets, possibly being dragged by the explosive outflow.

In this work, we present EDRIS (French for Distance Estimator for Incomplete Supernova Surveys), a cosmological inference framework tailored to reconstruct unbiased cosmological distances from type Ia supernovae light-curve parameters. This goal is achieved by including data truncation directly in the statistical model which takes care of the standardization of luminosity distances. It allows us to build a single-step distance estimate by maximizing the corresponding likelihood, free from the biases the survey detection limits would introduce otherwise. Moreover, we expect the current worldwide statistics to be multiplied by O(10) in the upcoming years. This provides a new challenge to handle as the cosmological analysis must stay computationally towable. We show that the optimization methods used in EDRIS allow for a reasonable time complexity of O($N^2$) resulting in a very fast inference process (O(10s) for 1500 supernovae).

Recent observations and statistical studies have revealed that a significant fraction of hydrogen-poor superluminous supernovae (SLSNe-I) exhibit light curves that deviate from the smooth evolution predicted by the magnetar-powered model, instead showing one or more bumps after the primary peak. However, the formation mechanisms of these post-peak bumps remain a matter of debate. Furthermore, previous studies employing the magnetar-powered model have typically assumed a fixed magnetic inclination angle and neglected the effects of magnetar precession. However, recent research has shown that the precession of newborn magnetars forming during the collapse of massive stars causes the magnetic inclination angle to evolve over time, thereby influencing magnetic dipole radiation. In this paper, therefore, we incorporate the effects of magnetar precession into the magnetar-powered model to develop the precessing magnetar-powered model. Using this model, we successfully reproduce the multi-band light curves of 6 selected representative SLSNe-I with post-peak bumps. Moreover, the derived model parameters fall within the typical parameter range for SLSNe-I. By combining the precessing magnetars in SLSNe-I and long GRBs, we find that the ellipticity of magnetars is related to the dipole magnetic field strength, which may suggest a common origin for the two phenomena. Our work provides a potential explanation for the origin of post-peak bumps in SLSNe-I and offers evidence for the early precession of newborn magnetars formed in supernova explosions.

We present a novel reinforcement learning (RL) approach for solving the classical 2-level atom non-LTE radiative transfer problem by framing it as a control task in which an RL agent learns a depth-dependent source function $S(\tau)$ that self-consistently satisfies the equation of statistical equilibrium (SE). The agent's policy is optimized entirely via reward-based interactions with a radiative transfer engine, without explicit knowledge of the ground truth. This method bypasses the need for constructing approximate lambda operators ($\Lambda^*$) common in accelerated iterative schemes. Additionally, it requires no extensive precomputed labeled datasets to extract a supervisory signal, and avoids backpropagating gradients through the complex RT solver itself. Finally, we show through experiment that a simple feedforward neural network trained greedily cannot solve for SE, possibly due to the moving target nature of the problem. Our $\Lambda^*-\text{Free}$ method offers potential advantages for complex scenarios (e.g., atmospheres with enhanced velocity fields, multi-dimensional geometries, or complex microphysics) where $\Lambda^*$ construction or solver differentiability is challenging. Additionally, the agent can be incentivized to find more efficient policies by manipulating the discount factor, leading to a reprioritization of immediate rewards. If demonstrated to generalize past its training data, this RL framework could serve as an alternative or accelerated formalism to achieve SE. To the best of our knowledge, this study represents the first application of reinforcement learning in solar physics that directly solves for a fundamental physical constraint.

X-ray observations can be used to effectively probe the galactic ecosystem, particularly its hot and energetic components. However, existing X-ray studies of nearby star-forming galaxies are limited by insufficient data statistics and a lack of suitable spectral modeling to account for X-ray emission and absorption geometry. We present results from an X-ray spectral study of M51 using 1.3-Ms Chandra data, the most extensive for such a galaxy. This allows the extraction of diffuse X-ray emission spectra from spiral arm phase-dependent regions using a logarithmic spiral coordinate system. A hierarchical Bayesian approach analyzes these spectra, testing models from simple 1-T hot plasma to those including distributed hot plasma and X-ray-absorbing cool gas. We recommend a model fitting the spectra well, featuring a galactic corona with a lognormal temperature distribution and a disk with mixed X-ray emissions and absorption. In this model, only half of the coronal emission is subject to internal absorption. The best-fit absorbing gas column density is roughly twice that inferred from optical extinction of stellar light. The temperature distribution shows a mean temperature of $\sim 0.1$ keV and an average one-dex dispersion that is enhanced on the spiral arms. The corona's radiative cooling might balance the mechanical energy input from stellar feedback. These results highlight the effectiveness of X-ray mapping of the corona and cool gas in spiral galaxies.

The variability mechanisms from jetted AGNs are still under debate. Here the damped random walk (DRW) model, implemented through Gaussian Processe (GPs), is used to fit the $ZTF$ long-term optical light curves of 1684 $\gamma$-ray emission jetted AGNs. This analysis yields one of the largest samples with characteristic optical variability timescales for jetted AGNs. A single DRW model from GPs can fit the optical light curve of most jetted AGNs well/potentially well, while there are still some jetted AGNs whose light curve can not be fitted well by a single DRW model. After the jet power, proxied by gamma-ray luminosity, is introduced as a new parameter, new relationships among intrinsic variability time scales, black hole mass and jet power are discovered for efficient accretion AGNs ($\tau^{\rm in} \propto M_{\rm BH}^{0.29^{+0.06}_{-0.06}}P_{\rm jet}^{-0.3^{+0.03}_{-0.03}}$ with scatter of approximately 0.09~dex) and for inefficient accretion AGNs ($\tau^{\rm in} \propto M_{\rm BH}^{0.06^{+0.07}_{-0.07}}P_{\rm jet}^{0.37^{+0.11}_{-0.11}}$ with scatter of approximately 0.14~dex), respectively. Our results support that the optical variability of jetted AGNs with efficient accretion may originate within the standard accretion disk at UV emitting radii similar to non-jetted AGNs, and is directly related to the acceleration of shock in the jet and then enhanced through the beaming effect in beamed AGNs. For the jetted AGNs with inefficient accretion, the intrinsic timescale is consistent with the escape timescale of electrons.

One of the most important discoveries in modern cosmology is cosmic acceleration. However, we find that today's universe could decelerate in the statistically preferred Chevallier-Polarski-Linder (CPL) scenario over the $\Lambda$CDM model by cosmic microwave background, type Ia supernova and DESI's new measurements of baryon acoustic oscillations. Using various datasets, at a beyond $5\,\sigma$ confidence level, we demonstrate that the universe experiences a triple deceleration during its evolution and finally reaches the state of the ''Big Stall", which predicts that: (i) the universe suddenly comes to a halt in the distant future; (ii) its eventual destiny is dominated by dark matter rather than dark energy ; (iii) it ultimately retains an extremely small fraction of dark energy but exerts an extremely large pressure. Our findings profoundly challenge the established understanding of cosmic acceleration and enrich our comprehension of cosmic evolution.

Baryonic effects created by feedback processes associated with galaxy formation are an important, poorly constrained systematic effect for models of large-scale structure as probed by weak gravitational lensing. Upcoming surveys require fast methods to predict and marginalize over the potential impact of baryons on the total matter power spectrum. Here we use the FLAMINGO cosmological hydrodynamical simulations to test a recent proposal to approximate the matter power spectrum as the sum of the linear matter power spectrum and a constant multiple, $A_{\rm mod}$, of the difference between the linear and non-linear gravity-only power spectra. We show that replacing this constant multiple with a one-parameter family of sigmoid functions of the wavenumber $k$ allows to us match the predictions of simulations with different feedback strengths for $z \leq 1, k < 3~h\cdot{\rm Mpc}^{-1}$, and the different cosmological models in the FLAMINGO suite. The baryonic response predicted by FLAMINGO models that use jet-like AGN feedback instead of the fiducial thermally-driven AGN feedback can also be reproduced, but at the cost of increasing the number of parameters in the sigmoid function from one to three. The assumption that $A_{\rm mod}$ depends only on $k$ breaks down for decaying dark matter models, highlighting the need for more advanced baryon response models when studying cosmological models that deviate strongly from $\Lambda$CDM.

This study presents a detailed timing analyses of two cataclysmic variables (CVs), [PK2008] HalphaJ115927 and IGR J14091-610, utilizing the optical data from the Transiting Exoplanet Survey Satellite (TESS). Periods of 7.20$\pm$0.02 h, 1161.49$\pm$0.14 s, and 1215.99$\pm$0.15 s are presented for [PK2008] HalphaJ115927, and are interpreted as the probable orbital, spin, and beat periods of the system, respectively. The presence of multiple periodic variations suggests that it likely belongs to the intermediate polar (IP) category of magnetic CVs. Interestingly, [PK2008] HalphaJ115927 exhibits a unique and strong periodic modulation at 5.66$\pm$0.29 d, which may result from the precession of an accretion disc, similar to the IP TV Col. The detection of a spin signal of 576.63$\pm$0.03 s and inferred orbital signal of $\sim$ 15.84 h supports the classification of IGR J14091-610 as an IP. The identification of such a long orbital period adds a new example to the limited population of long-period IPs. The observed dominant signal at the second harmonic of the orbital frequency also suggests ellipsoidal modulation of the secondary in this system. The observed double-peaked spin pulse profile in [PK2008] HalphaJ115927 likely results from two-pole accretion, where both poles contribute to the spin modulation, and their geometry allows equal visibility of both accreting poles. In contrast, IGR J14091-610 exhibits a single-peaked sinusoidal like spin pulse, attributed to the changing visibility of the accretion curtains due to a relatively low dipole inclination. The present observations indicate that accretion in both systems occurs predominantly through a disc.

Fast radio bursts (FRBs) are luminous radio transients with millisecond duration. For some active repeaters, such as FRBs 20121102A and 20201124A, more than a thousand bursts have been detected by the Five-hundred-meter Aperture Spherical radio Telescope (FAST). The waiting time (WT) distributions of both repeaters, defined as the time intervals between adjacent (detected) bursts, exhibit a bimodal structure well-fitted by two log-normal functions. Notably, the time scales of the long-duration WT peaks for both repeaters show a decreasing trend over time. These similar burst features suggest that there may be a common physical mechanism for FRBs~20121102A and 20201124A. In this paper, we {revisit} the neutron star (NS)--white dwarf (WD) binary model with an eccentric orbit to account for the observed changes in the long-duration WT peaks. According to our model, the shortening of the WT peaks corresponds to the orbital period decay of the NS-WD binary. We consider two mass transfer modes, namely, stable and unstable mass transfer, to examine how the orbital period evolves. Our findings reveal distinct evolutionary pathways for the two repeaters: for FRB~20121102A, the NS-WD binary likely undergoes a combination of common envelope (CE) ejection and Roche lobe overflow, whereas for FRB~20201124A the system may experience multiple CE ejections. These findings warrant further validation through follow-up observations.

The Black Hole Explorer (BHEX) will be the first sub-mm wavelength Space Very-Long-Baseline Interferometry (VLBI) mission. It targets astronomical imaging with the highest ever spatial resolution to enable detection of the photon ring of a supermassive black hole. BHEX is being proposed for launch in 2031 as a NASA Small Explorers mission. BHEX science goals and mission opportunity require a high precision lightweight spaceborne antenna. A survey of the technology landscape for realizing such an antenna is presented. Technology readiness (TRL) for the antenna is discussed and assessed to be at TRL 5. An update on our technology maturation efforts is provided. Design studies leading to the conceptual design of a metallized carbon fiber reinforced plastic (CFRP) technology based antenna with a mass of only $\dim 50$ kg, incorporating a 3.4 m primary reflector with a surface precision of < 40 $\mu$m to allow efficient operation up to 320 GHz are outlined. Current plans anticipate attaining TRL6 in 2026 for the BHEX antenna. Completed design studies point to a large margin in surface precision which opens up opportunities for applications beyond BHEX, at significantly higher THz frequencies.

We present new rotational period estimates for 216 Jupiter Trojans using photometric data from the Zwicky Transient Facility (ZTF), including 80 Trojans with previously unknown periods. Our analysis reveals rotation periods ranging from 4.6 hours to 447.8 hours. These results support the existence of a spin barrier for Trojans larger than 10 km, with periods clustering between 4 and 4.8 hours. This spin barrier is roughly twice as long as that observed for main-belt asteroids, suggesting that Jupiter Trojans have significantly lower bulk densities, likely due to a higher fraction of ices and volatile materials in their composition. We identify three new Trojans with reliable rotation periods near the spin barrier, doubling the number of known Trojans in this critical period range. Using these results, we estimate a mean density of approximately 0.52 g/cm^3 for rubble-pile Trojans. Our findings support the growing evidence that many Trojans are rubble-pile bodies with distinct physical properties compared to main-belt asteroids. Looking forward, we anticipate that data from the Vera C. Rubin Observatory's Legacy Survey of Space and Time (LSST) will provide rotational period estimates for several hundred thousand Trojans, down to objects as small as 1 km, enabling a more detailed investigation of their rotational properties and internal structure.

Using JWST near-infrared data of the inner Orion Nebula, \citet{Pearson_McCaughrean_2023} detected 40 binary systems they proposed to be Jupiter-Mass Binary Objects (JuMBOs) -- although their actual nature is still in debate. Only one of the objects, JuMBO\,24, was detected in the radio continuum. Here, we report on new radio continuum (10 GHz) Karl G. Jansky Very Large Array (VLA) detections of the radio counterpart to JuMBO\,24, and on an unsuccessful search for 5 GHz continuum emission with the High Sensitivity Array (HSA). From our new VLA detections and adopting a distance to the region, we set an upper limit of $\simeq 6$~km~s$^{-1}$ to the velocity of the radio source in the plane of the sky. This upper limit favors an origin for this source similar to that of stars, that is, from a stationary contracting core. The nature of the radio emission remains uncertain but the lack of strong variability (all VLA observations are consistent with a steady flux of $\sim$50 $\mu$Jy), of detection on long HSA baseline, and of detectable circular polarization in VLA data do not favor a non-thermal origin.

In this work we examine the baryon acoustic oscillations (BAO) in 2D angular and redshift space $\{\theta, \Delta z\}$, with $\Delta z$ denoting the redshift difference between two given angular shells. We thus work in the context of tomographic analyses of the large scale structure (LSS) where data are sliced in different redshift shells and constraints on Cosmology are extracted from the auto and cross-angular spectra of two different probes, namely the standard galaxy angular density fluctuations (ADF, or 2D clustering), and the galaxy angular redshift fluctuations (ARF). For these two observables we study by first time how the BAO peak arises in the $\{\theta, \Delta z\}$ plane. Despite being a weak feature (particularly for $\Delta z \neq 0$), a Fisher forecast analysis shows that, a priori, most of the information on cosmological and galaxy bias parameters is carried by the BAO features in shell auto- and cross-angular power spectra. The same study shows that a joint probe analysis (ADF+ARF) increases the Fisher determinant associated to cosmological parameters such as $H_0$ or the Dark Energy Chevallier-Polarski-Linder (CPL) parameters $\{w_0,w_a\}$ by at least an order of magnitude. We also study how the Fisher information on cosmological and galaxy bias-related parameters behaves under different redshift shell configurations: including cross-correlations to neighbour shells extending up to $(\Delta z)^{\rm tot}\sim 0.6$ ($(\Delta z)^{\rm tot}\sim 0.4$) for ADF (ARF) is required for Fisher information to converge. At the same time, configurations using narrow shell widths ($\sigma_z \leq 0.02$) preserve the cosmological information associated to peculiar velocities and typically yield Fisher determinants that are about two orders of magnitudes larger than for wider shell ($\sigma_z>0.02$) configurations.

The transfer of material between planetary bodies due to impact events is important for understanding planetary evolution, meteoroid impact fluxes, the formation of near-Earth objects (NEOs), and even the provenance of volatile and organic materials at Earth. This study investigates the dynamics and fate of lunar ejecta reaching Earth. We employ the high-accuracy IAS15 integrator withing the REBOUND package to track for 100,000 years the trajectories of 6,000 test particles launched from various lunar latitudes and longitudes. Our model incorporates a realistic velocity distribution for ejecta fragments (tens of meters in size), derived form large lunar cratering events. Our results show that 22.6% of lunar ejecta collide with Earth, following a power-law $C(t) \propto t^{0.315}$ with half of the impacts occurring within ~10,000 years. We also confirm that impact events on the Moon's trailing hemisphere serve as a dominant source of Earth-bound ejecta, consistent with previous studies. Additionally, a small fraction of ejecta remains transiently in near-Earth space, providing evidence that lunar ejecta may contribute to the NEO population. This aligns with recent discoveries of Earth co-orbitals such as Kamo'oalewa (469219, 2016 HO3) and 2024 PT5, both exhibiting spectral properties consistent with lunar material. These findings enhance our understanding of the lunar ejecta flux to Earth, providing insights into the spatial and temporal patterns of this flux and its broader influence on the near-Earth environment.

In certain scenarios, the accreted angular momentum of plasma onto a black hole could be low; however, how the accretion dynamics depend on the angular momentum content of the plasma is still not fully understood. We present three-dimensional, general relativistic magnetohydrodynamic simulations of low angular momentum accretion flows around rapidly spinning black holes (with spin $a = +0.9$). The initial condition is a Fishbone-Moncrief (FM) torus threaded by a large amount of poloidal magnetic flux, where the angular velocity is a fraction $f$ of the standard value. For $f = 0$, the accretion flow becomes magnetically arrested and launches relativistic jets but only for a very short duration. After that, free-falling plasma breaks through the magnetic barrier, loading the jet with mass and destroying the jet-disk structure. Meanwhile, magnetic flux is lost via giant, asymmetrical magnetic bubbles that float away from the black hole. The accretion then exits the magnetically arrested state. For $f = 0.1$, the dimensionless magnetic flux threading the black hole oscillates quasi-periodically. The jet-disk structure shows concurrent revival and destruction while the gas outflow efficiency at the event horizon changes accordingly. For $f \geq 0.3$, we find that the dynamical behavior of the system starts to approach that of a standard accreting FM torus. Our results thus suggest that the accreted angular momentum is an important parameter that governs the maintenance of a magnetically arrested flow and launching of relativistic jets around black holes.

Inverse Compton scattering by the thermal motions of electrons is believed to produce polarized hard X-rays in active galactic nuclei and black-hole binaries. Meanwhile, plasma within the plunging region of the black hole free falls into the event horizon with a bulk relativistic speed, which could also imprint polarization on up-scattered photons but has not been discussed in detail. To examine this, we computed polarimetric signatures via general relativistic ray-tracing of a toy model consisting of an accreting, geometrically thin plasma with moderate optical depth, falling onto the black hole with a bulk relativistic speed within the plunging region. We show that the maximum spatially unresolved linear polarization could be as large as approximately $7 - 8$ percent when the black hole is viewed near edge-on, while the corresponding resolved linear polarization could be roughly $50$ percent. The large discrepancy between the two is due to 1) dilution from the radiation outside the plunging region and 2) substantial cancellations of the Stokes $Q$ and $U$ fluxes. The resultant polarization contributed by bulk Comptonization could nevertheless exceed that of thermal electron scattering in a Novikov-Thorne disk. Our results thus suggest a new model for imprinting considerable polarization on the electromagnetic observables of accreting black holes. Measurements of X-ray polarization from black-hole binaries and the central black hole of active galactic nuclei could provide direct detection of the plunging region and help constrain plasma properties in the immediate vicinity of the event horizon.

Strong gravitational lensing is a powerful tool for probing the nature of dark matter, as lensing signals are sensitive to the dark matter substructure within the lensing galaxy. We present a comparative analysis of strong gravitational lensing signatures generated by dark matter subhalo populations using two different approaches. The first approach models subhalos using an empirical model, while the second employs the Galacticus semi-analytic model of subhalo evolution. To date, only empirical approaches have been practical in the analysis of lensing systems, as incorporating fully physical models was computationally infeasible. To circumvent this, we utilize a generative machine learning algorithm, known as a normalizing flow, to learn and reproduce the subhalo populations generated by Galacticus. We demonstrate that the normalizing flow algorithm accurately reproduces the Galacticus subhalo distribution while significantly reducing computation time compared to direct simulation. Moreover, we find that subhalo populations from Galacticus produce comparable results to the empirical model in replicating observed lensing signals under the fiducial dark matter model. This work highlights the potential of machine learning techniques in accelerating astrophysical simulations and improving model comparisons of dark matter properties.

A large fraction of the baryon budget at $z<1$ resides in large-scale filaments in the form of diffuse intergalactic gas, and numerous studies have reported a significant correlation between the strength of the absorptions produced by this gas in the spectra of bright background sources, and impact parameter to cosmic filaments intersected by these sightlines. However, a similar relation is harder to determine for the warm-hot phase of the intergalactic gas, since its higher Doppler parameter and significantly lower neutral gas fraction makes this gas difficult to detect in absorption. We use a sample of 13 broad Ly$\alpha$ absorbers (BLAs) detected in the HST/COS spectrum of a single QSO ($z\sim0.27$), whose sightline intersects several inter-cluster axes, to study the relation between BLAs and the large-scale structure of the Universe. Given their Doppler parameters of $b>40$ km s$^{-1}$, BLAs are good tracers of warm-hot intergalactic gas. We use VLT/MUSE and VLT/VIMOS data to infer local overdensities of galaxies at the redshifts of the BLAs, and to assess the potential association of the BLAs with nearby galaxies. We find that out of the 13 BLAs in our sample, four are associated with a strong overdensity of galaxies, and four with tentative overdensities. The remaining five are located at redshifts where we do not identify any excess of galaxies. We find that these overdensities of galaxies at the redshift of BLAs are local, and they vanish when larger cosmic volumes are considered, in terms of a larger velocity offset to the BLA or larger impact parameter to the QSO sightline. Finally, we find a positive correlation between the total hydrogen column densities inferred from the BLAs, and the relative excess of galaxies at the same redshifts, consistent with the picture where warm-hot gas resides deep within the gravitational potential well of cosmic filaments.

High-energy gamma rays have been detected in the region of LHAASO~J2108+5157 by the Fermi--LAT, HAWC and LHAASO-KM2A observatories. Cygnus~OB2 in Cygnus--X has been confirmed as the first strong stellar cluster PeVatron in our Galaxy. Thus, the star--forming regions Kronberger~80 and Kronberger~82, located in the field of LHAASO~J2108+5157, are analyzed to evaluate their stellar population and potential as associated PeVatron candidates. A distance of 10~kpc is adopted for Kronberger~80, while $\sim$1.6~kpc is estimated for Kronberger~82. Based on stellar densities, we report that their cluster radii are 2.5$\arcmin$ and 2.0$\arcmin$, while IR photometry reveals poor stellar content in massive O-type stars in both cases. From optical data, the estimation of cluster ages are 5--12.6~Myr and $\lesssim$ 5~Myr, respectively. We conclude that, in contrast to the stellar content of Cygnus~OB2, it is unlikely that Kronberger~80 and Kronberger~82 are PeVatrons associated with LHAASO~J2108+5157. The presence of a PeVatron in this region remains a mystery, but we confirm that the two Kronberger regions are star--forming regions undergoing formation rather than evolution.

Any attempt to understand the ubiquitous nature of the magnetic field in the present universe seems to lead us towards its primordial origin. For large-scale magnetic fields, however, their strength and length scale may not necessarily originate from a singular primordial mechanism, namely inflationary magnetogenesis, which has been a popular consideration in the literature. In this paper, we propose a minimal scenario wherein a large-scale magnetic field is generated from the inflationary perturbation without any non-conformal coupling. Due to their origin in the inflationary scalar spectrum, these primordial fields are inherently weak, with their strength suppressed by the small amplitude of scalar fluctuations. We then consider the coupling between this large-scale weak primordial magnetic field and a light axion of mass $<10^{-28}$ eV, which is assumed to be frozen in a misaligned state until the photon decoupling. After the decoupling, when the universe enters into a dark age, the light axion coherently oscillates. By appropriately tuning the axion-photon coupling parameter $\alpha$, we demonstrate that a large-scale magnetic field of sufficient strength can indeed be generated through tachyonic resonance. We further show that the produced magnetic field induces a unique spectrum with multiple peaks of secondary gravitational waves, which the upcoming CMB-S4 can probe through B-mode polarization. The strength can be sufficient enough to violate the PLANCK bound on tensor-to-scalar ratio $r \lesssim 0.036$. Such a violation leads to a constraint on $\alpha \lesssim 80$. With this limiting value of the coupling, we find that present-day magnetic field strength could be as high as $10^{-10}$ Gauss at $\Mpc$ scale, consistent with observation.

Observations of auroras on exoplanets would provide numerous insights into planet-star systems, including potential detections of the planetary magnetic fields, constraints on host-star wind properties, and information on the thermal structures of planets. However, there have not yet been any discoveries of auroras on exoplanets. In this paper, we focus on the search for infrared auroral emission from the molecular ion H$_3^+$, which is common in the atmospheres of solar system planets Jupiter, Saturn, and Uranus. Using Keck/NIRSPEC high-resolution spectroscopy, we search for H$_3^+$ emission from two hot Jupiters, WASP-80b and WASP-69b. We do not see any evidence of emission in the observed spectra when cross-correlating with an H$_3^+$ spectral model or when using an auto-correlation approach to search for any significant features. We therefore place upper limits on the total emission of $5.32 \times 10^{18}$ W for WASP-80b and $1.64 \times 10^{19}$ W for WASP-69b. These upper limits represent the most stringent limits to date and approach the regime of emission suspected from theoretical models.

Spotted stars in eclipsing binary systems allow us to gather significant information about the stellar surface inhomogeneities that is otherwise impossible from only photometric data. Starspots can be scanned using the eclipse (or transit) mapping technique, which takes advantage of the passage of a companion star (or planet) in front of a spotted giant star in a binary system. Based on the characteristics of their ultra-precise space photometric light curves, we compile a list of eclipsing binaries whose primary component is a spotted subgiant or giant star, with the aim of applying the eclipse mapping technique to them. Eclipsing binaries with giant primaries were selected from Transiting Exoplanet Survey Satellite (TESS) light curves by visual inspection. Spots showing up as bumps during eclipses are modeled with an eclipse mapping technique specialized for two stars, and the number of spots are found with the help of Bayes factors. The full light curves themselves were analyzed with time series spot modeling, and the results of the two approaches were compared. We present a catalog of 29 eclipsing close binaries with active giant components and analyze TIC 235934420, TIC 271892852 and TIC 326257590 from the Continuous Viewing Zones (CVZ) of TESS. Remarkable agreement is found between the starspot temperatures, sizes, and longitudes from the eclipse mapping results and the corresponding full light curve solutions. Spots are always present at the substellar points of the tidally locked binaries. Data from the TESS CVZ allow us to follow the changes of spot patterns on yearly timescales.

The cluster environment has been shown to affect the molecular gas content of cluster members, yet a complete understanding of this often subtle effect has been hindered due to a lack of detections over the full parameter space of galaxy star formation rates and stellar masses. Here we stack CO(2-1) spectra of z~1.6 cluster galaxies to explore the average molecular gas fractions of galaxies both at lower mass (log(M/solar mass)~9.6) and further below the Star Forming Main Sequence (SFMS; DeltaMS~ -0.9) than other literature studies; this translates to a 3sigma gas mass limit of ~7x10^9 solar masses for stacked galaxies below the SFMS. We divide our sample of 54 z~1.6 cluster galaxies, derived from the Spitzer Adaptation of the Red-Sequence Cluster Survey, into 9 groupings, for which we recover detections in 8. The average gas content of the full cluster galaxy population is similar to coeval field galaxies matched in stellar mass and star formation rate. However, when further split by CO-undetected and CO-detected, we find that galaxies below the SFMS have statistically different gas fractions from the field scaling relations, spanning deficiencies to enhancements from 2sigma below to 3sigma above the expected field gas fractions, respectively. These differences between z=1.6 cluster and field galaxies below the SFMS are likely due to environmental processes, though further investigation of spatially-resolved properties and more robust field scaling relation calibration in this parameter space are required.

Context. Extreme-ultraviolet (EUV) observations have revealed small-scale transient brightenings that may share common physical mechanisms with larger-scale solar flares. A notable feature of solar and stellar flares is the presence of quasi-periodic pulsations (QPPs), which are considered a common and potentially intrinsic characteristic. Aims. We investigate the properties of QPPs detected in EUV brightenings, which are considered small-scale flares, and compare their statistical properties with those observed in solar and stellar flares. Methods. We extracted integrated light curves of 22,623 EUV brightenings in two quiet Sun regions observed by the Solar Orbiter/Extreme Ultraviolet Imager and identified QPPs in their light curves using Fourier analysis. Results. Approximately 2.7 % of the EUV brightenings exhibited stationary QPPs. The QPP occurrence rate increased with the surface area, lifetime, and peak brightness of the EUV brightenings. The detected QPP periods ranged from approximately 15 to 260 seconds, which is comparable to the periods observed in solar and stellar flares. Consistent with observations of QPPs in solar and stellar flares, no correlation was found between the QPP period and peak brightness. However, unlike the trend observed in solar flares, no correlation was found between the QPP period and lifetime/length scale. Conclusions. The presence of QPPs in EUV brightenings supports the interpretation that these events may be small-scale manifestations of flares, and the absence of period scaling with loop length further suggests that standing waves may not be the primary driver of QPPs in these events.

The trans-neptunian object (58534) 1997 CQ$_{29}$ (a.k.a. Logos) is a resolved wide binary in the dynamically Cold Classical population. With Hubble Space Telescope resolved observations where the primary Logos is well separated from its secondary Zoe it can be established that Logos has a time-variable brightness. Logos' brightness varied by several tenths of a magnitude over a short timescale of hours while the brightness variability of Zoe was on a longer timescale. New unresolved ground-based observations obtained with the Lowell Discovery Telescope and the Magellan-Baade telescope confirm at least one highly variable component in this system. With our ground-based observations and photometric constraints from space-based observations, we suggest that the primary Logos is likely a close/contact binary whose rotational period is 17.43$\pm$0.06 h for a lightcurve amplitude of 0.70$\pm$0.07 mag while Zoe is potentially a (very) slow rotator with an unknown shape. Using the Candela software, we model the Logos-Zoe system and predict its upcoming mutual events season using rotational, physical, and mutual orbit parameters derived in this work or already published. Zoe's shape and rotational period are still uncertain, so we consider various options to better understand Zoe. The upcoming mutual event season for Logos-Zoe starts in 2026 and will last for four years with up to two events per year. Observations of these mutual events will allow us to significantly improve the physical and rotational properties of both Logos and Zoe.

Galaxy mergers are pivotal events in the evolutionary history of galaxies, with their impact believed to be particularly significant in dwarf galaxies. We report the serendipitous identification of an isolated merging dwarf system with a total stellar mass of M$_{\rm \star}$$\sim$10$^{9.7}$M$_{\rm \odot}$, located in the centre of a cosmic void. This system is one of the rare examples, and possibly the first, of merging dwarf galaxy pairs studied within the central region of a cosmic void. Using CAVITY PPAK-IFU data combined with deep optical broadband imaging from the Isaac Newton Telescope, we analysed the kinematics and ionized gas properties of each dwarf galaxy in the system by employing a full spectral fitting technique. The orientation of this merging pair relative to the line of sight allowed us to determine the dynamical mass of each component, showing that both had similar dynamical masses within galactocentric distances of up to 2.9 kpc. While the gas-phase metallicity of both components is consistent with that of star-forming dwarf galaxies, the star formation rates observed in both components exceed those typically reported for equally massive star-forming dwarf galaxies. This indicates that the merger has presumably contributed to enhancing star formation. Furthermore, we found no significant difference in the optical g-r colour of this merging pair compared to other merging dwarf pairs across different environments. While most merging events occur in group-like environments with high galaxy density and the tidal influence of a host halo, and isolated mergers typically involve galaxies with significant mass differences, the identified merging pair does not follow these patterns. We speculate that the global dynamics of the void or past three-body encounters involving components of this pair and a nearby dwarf galaxy might have triggered this merging event.

Understanding gas flows between galaxies and their surrounding circum-galactic medium (CGM) is crucial to unveil the mechanisms regulating galaxy evolution, especially in the early Universe. However, observations of the CGM around massive galaxies at z>6 remain limited, particularly in the cold gas phase. In this work, we present multi-configuration ALMA observations of [CII]$\lambda158,\mu$m and millimetre continuum emission in the z~6.4 quasar PSOJ183+05, to trace the cold CGM and investigate the presence of outflows. We find clumpy [CII] emission, tracing gas up to a ~6 kpc radius, consistent with the interface region between the interstellar medium (ISM) and CGM. The [CII] kinematics shows a rotating disk and a high-velocity, biconical outflow extending up to 5 kpc. The inferred mass outflow rate is ~930 MSun/yr, among the highest at z>6, and comparable to the star-formation rate. These findings suggest that quasar-driven outflows can rapidly transfer energy and momentum to the CGM, without immediately quenching star formation in the host galaxy ISM. This supports a delayed feedback scenario, in which outflows reshape CGM conditions and regulate future gas accretion over longer timescales. Combining high-resolution and sensitive ALMA data with observations from JWST and MUSE will be crucial to map the CGM across its different phases and build a comprehensive picture of the baryon cycle in the first massive galaxies.

The Milky Way has a large population of dwarf galaxy satellites. Their properties are sensitive to both cosmology and the physical processes underlying galaxy formation, but these properties are still not properly characterized for the entire satellite population. We aim to provide the most accurate systemic dynamical and metallicity properties of the dwarf galaxy Bo\"otes II (Boo II). We use a new spectroscopic sample of 39 stars in the field of Boo II with data from the Fiber Large Array Multi Element Spectrograph (FLAMES) mounted on the Very Large Telescope (VLT). The target selection is based on a combination of broadband photometry, proper motions from Gaia, and the metallicity-sensitive narrow-band photometry from the Pristine survey that is ideal for removing obvious Milky Way contaminants. We found 9 new members, including 5 also in the recent work of Bruce et al. (2023), and the farthest member to date (5.7 half-light radii from Boo II centroid), extending the spectroscopic spatial coverage of this system. Our metallicity measurements based on the Calcium triplet lines leads to the detection of the two first extremely metal-poor stars (EMPS, [Fe/H] < -3.0) in Boo II. Combining this new dataset with literature data refines Boo II's velocity dispersion (5.6km/s), systemic velocity(-126.8 km/s) and shows that it does not show any sign of a significant velocity gradient. We are thus able to confirm the kinematic and metallicity properties of the satellite as well as identify new members for future high-resolution analyses.

Context. To date, more than a hundred debris disks have been spatially resolved. Among them, the young system HD 120326 stands out, displaying different disk substructures on both intermediate (30-150 au) and large (150-1000 au) scales. Aims. We present new VLT/SPHERE (1.0-1.8 $\mu$m) and ALMA (1.3 mm) data of the debris disk around HD 120326. By combining them with archival HST/STIS (0.2-1.0 $\mu$m) and archival SPHERE data, we have been able to examine the morphology and photometry of the debris disk, along with its dust properties. Methods. We present the open-access code MoDiSc (Modeling Disks in Scattered light) to model the inner belt jointly using the SPHERE polarized and total intensity observations. Separately, we modeled the ALMA data and the spectral energy distribution (SED). We combined the results of both these analyses with the STIS data to determine the global architecture of HD 120326. Results. For the inner belt, identified as a planetesimal belt, we derived a semi-major axis of 43 au, fractional luminosity of 1.8 x 10-3 , and maximum degree of polarization of 45-57 % at 1.6 $\mu$m. The spectral slope of its reflectance spectrum is red between 1.0 and 1.3 $\mu$m and gray between 1.3 and 1.8 $\mu$m. Additionally, the SPHERE data show that there could be a halo of small particles or a second belt at distances <150 au. Using ALMA, we derived in the continuum (1.3 mm) an integrated flux of 541-581 $\mu$Jy. We did not detect any 12CO emission. At larger separations (>150 au), we highlight a spiral-like feature spanning hundreds of astronomical units in the STIS data. Conclusions. Further data are needed to confirm and better constrain the dust properties and global morphology of HD 120326.

Bayesian field-level inference of galaxy clustering guarantees optimal extraction of all cosmological information, provided that the data are correctly described by the forward model employed. The latter is unfortunately never strictly the case. A key question for field-level inference approaches then is where the cosmological information is coming from, and how to ensure that it is robust. In the context of perturbative approaches such as effective field theory, some progress on this question can be made analytically. We derive the parameter posterior given the data for the field-level likelihood given in the effective field theory, marginalized over initial conditions in the zero-noise limit. Particular attention is paid to cutoffs in the theory, the generalization to higher orders, and the error made by an incomplete forward model at a given order. The main finding is that, broadly speaking, an $m$-th order forward model captures the information in $n$-point correlation functions with $n \leqslant m+1$. Thus, by adding more terms to the forward model, field-level inference is made to automatically incorporate higher-order $n$-point functions. Also shown is how the effect of an incomplete forward model (at a given order) on the parameter inference can be estimated.

Self-interacting neutrinos provide an intriguing extension to the Standard Model, motivated by both particle physics and cosmology. Recent cosmological analyses suggest a bimodal posterior for the coupling strength $G_{\rm eff}$, favoring either strong or moderate interactions. These interactions modify the scale-dependence of the growth of cosmic structures, leaving distinct imprints on the matter power spectrum at small scales, $k\,>\,0.1\,{\rm Mpc}^{-1}$. For the first time, we explore how the 21-cm power spectrum from the cosmic dawn and the dark ages can constrain the properties of self-interacting, massive neutrinos. The effects of small-scale suppression and enhancement in the matter power spectrum caused by self-interacting neutrinos propagate to the halo mass function, shaping the abundance of small- and intermediate-mass halos. It is precisely these halos that host the galaxies responsible for driving the evolution of the 21-cm signal during the cosmic dawn. We find that HERA at its design sensitivity can improve upon existing constraints on $G_{\rm eff}$ and be sensitive to small values of the coupling, beyond the reach of current and future CMB experiments. Crucially, we find that the combination of HERA and CMB-S4 can break parameter degeneracies, significantly improving the sensitivity to $G_{\rm eff}$ over either experiment alone. Finally, we investigate the prospects of probing neutrino properties with futuristic Lunar interferometers, accessing the astrophysics-free 21-cm power spectrum during the dark ages. The capability of probing small scales of these instruments will allow us to reach a percent-level constraint on the neutrino self-coupling.

The dust attenuation of galaxies is highly diverse and closely linked to stellar population properties and the star dust geometry, yet its relationship to galaxy morphology remains poorly understood. We present a study of 141 galaxies ($9<\log(\rm M_{\star}/\rm M_{\odot})<11.5$) at $1.7<z<3.5$ from the Blue Jay survey combining deep JWST/NIRCam imaging and $R\sim1000$ JWST/NIRSpec spectra. Using \texttt{Prospector} to perform a joint analysis of these data with non-parametric star-formation histories and a two-component dust model with flexible attenuation laws, we constrain stellar and nebular properties. We find that the shape and strength of the attenuation law vary systematically with optical dust attenuation ($A_V$), stellar mass, and star formation rate (SFR). $A_V$ correlates strongly with stellar mass for starbursts, star-forming galaxies and quiescent galaxies. The inclusion of morphological information tightens these correlations: attenuation correlates more strongly with stellar mass and SFR surface densities than with the global quantities. The Balmer decrement-derived nebular attenuation for 67 of these galaxies shows consistent trends with the stellar continuum attenuation. We detect a wavelength-dependent size gradient: massive galaxies ($\rm M_{\star}\gtrsim 10^{10}~M_{\odot}$) appear $\sim30\%$ larger in the rest-optical than in the rest-NIR, driven by central dust attenuation that flattens optical light profiles. Lower-mass systems exhibit more diverse size ratios, consistent with either inside-out growth or central starbursts. These results demonstrate that dust attenuation significantly alters observed galaxy structure and highlight the necessity of flexible attenuation models for accurate physical and morphological inference at cosmic noon.

Multiphase gas can be found in many astrophysical environments, such as galactic outflows, stellar wind bubbles, and the circumgalactic medium, where the interplay between turbulence, cooling, and viscosity can significantly influence gas dynamics and star formation processes. We investigate the role of viscosity in modulating turbulence and radiative cooling in turbulent radiative mixing layers (TRMLs). In particular, we aim to determine how different amounts of viscosity affect the Kelvin-Helmholtz instability (KHI), turbulence evolution, and the efficiency of gas mixing and cooling. Using idealized 2D numerical setups, we compute the critical viscosity required to suppress the KHI in shear flows characterized by different density contrasts and Mach numbers. These results are then used in a 3D shear layer setup to explore the impact of viscosity on cooling efficiency and turbulence across different cooling regimes. We find that the critical viscosity follows the expected dependence on overdensity and Mach number. Our viscous TRMLs simulations show different behaviors in the weak and strong cooling regimes. In the weak cooling regime, viscosity has a strong impact, resulting in laminar flows and breaking previously established inviscid relations between cooling and turbulence (albeit leaving the total luminosity unaffected). However, in the strong cooling regime, when cooling timescales are shorter than viscous timescales, key scaling relations in TRMLs remain largely intact. In this regime -- which must hold for gas to remain multiphase -- radiative losses dominate, and the system effectively behaves as non-viscous regardless of the actual level of viscosity. Our findings have direct implications for both the interpretation of observational diagnostics and the development of subgrid models in large-scale simulations.

This study comprehensively analyzes three open star clusters: SAI 16, SAI 81, and SAI 86 using Gaia DR3 data. Based on the ASteCA code, we determined the most probable star candidates (P >= 50%) and estimated the number of star members of each cluster as 125, 158, and 138, respectively. We estimated the internal structural parameters by fitting the King model to the observed RDPs, including the core, limited, and tidal radii. The isochrone fitting to the color-magnitude diagram provided log(age) values of 9.13 +/- 0.04, 8.10 +/- 0.04, and 8.65 +/- 0.04 and distances of 3790 +/- 94 pc, 3900 +/- 200 pc, and 3120 +/- 30 pc for SAI 16, SAI 81, and SAI 86, respectively. We also calculated their projected distances from the Galactic plane (X_sun, Y_sun) as well as their vertical distances (Z_sun), Galactocentric distances (R_gc), and total masses (M_C) in solar units, which are about 142 +/- 12, 302 +/- 17, and 192 +/- 14 for SAI 16, SAI 81, and SAI 86, respectively. Examining the dynamical relaxation state indicates that all three clusters are dynamically relaxed. By undertaking a kinematic analysis of the cluster data, the space velocity was determined. We calculated the coordinates of the apex point (A_o, D_o) using the AD diagram method along with the derivation of the solar motion parameters (S_sun, l_A, b_A). Through our detailed dynamic orbit analysis, we determined that the three SAI clusters belong to the young stellar disc, confirming their membership within this component of the Galactic structure.

We present an analysis of AGN activity within recently quenched massive galaxies at cosmic noon ($z\sim 2$), using deep Chandra X-ray observations of the Ultra-Deep Survey (UDS) field. Our sample includes over 4000 massive galaxies ($M_\ast > 10^{10.5}$ M$_{\odot}$) in the redshift range $1 < z < 3$, including more than 200 transitionary post-starburst (PSB) systems. We find that X-ray emitting AGN are detected in $6.2 \pm 1.5$ per cent of massive PSBs at these redshifts, a detection rate that lies between those of star-forming and passive galaxies ($8.2 \pm 0.5$ per cent and $5.7 \pm 0.8$ per cent, respectively). A stacking analysis shows that the average X-ray luminosity for PSBs is comparable to older passive galaxies, but a factor of $2.6 \pm 0.3$ below star-forming galaxies of similar redshift and stellar mass. The average X-ray luminosity in all populations appears to trace the star-formation rate, with PSBs showing low levels of AGN activity consistent with their reduced levels of star formation. We conclude that, on average, we see no evidence for excess AGN activity in the post-starburst phase. However, the low levels of AGN activity can be reconciled with the high-velocity outflows observed in many PSBs, assuming the rare X-ray detections represent short-lived bursts of black hole activity, visible $\sim$5 per cent of the time. Thus, X-ray AGN may help to maintain quiescence in massive galaxies at cosmic noon, but the evidence for a direct link to the primary quenching event remains elusive.

This study investigates the open clusters SAI 72 and SAI 75 using Gaia DR3 data, employing the Automated Stellar Cluster Analysis (ASteCA) tool to determine their structural and fundamental properties, including center coordinates, size, age, distance, mass, luminosity, and kinematics. Based on membership probabilities (P >= 50%), we identified 112 and 115 stars as probable members of SAI 72 and SAI 75, respectively. Radial density profile (RDP) analysis yielded cluster radii of 2.35 arcmin for SAI 72 and 2.19 arcmin for SAI 75. The spectral energy distribution (SED) fitting was performed to refine metallicity, distance, and color excess parameters, ensuring consistency within 1 sigma of isochrone-based estimates. Isochrone fitting of the color-magnitude diagram (CMD) suggests ages of 316 Myr and 302 Myr, with corresponding distances of 3160 +/- 80 pc and 3200 +/- 200 pc. We derived their Galactic positions, projected distances (X_sun, Y_sun), and vertical displacements (Z_sun). Mass function analysis estimates cluster masses of 612 +/- 174 solar masses for SAI 72 and 465 +/- 90 solar masses for SAI 75. Kinematic studies indicate that both clusters have reached dynamical equilibrium. The AD diagram method provided convergent point coordinates of (A, D)_o = (97.016 +/- 0.09, 4.573 +/- 0.05) for SAI 72 and (99.677 +/- 0.10, 1.243 +/- 0.09) for SAI 75. Orbital analysis confirms that both clusters follow nearly circular trajectories with low eccentricities and minor variations in apogalactic and perigalactic distances. Furthermore, we determine that SAI 72 and SAI 75 originated beyond the solar circle at R_Birth = 10.825 +/- 0.068 kpc and R_Birth = 9.583 +/- 0.231 kpc, respectively. Their maximum heights above the Galactic plane, Z_max, are 109 +/- 9 pc for SAI 72 and 232 +/- 24 pc for SAI 75, reinforcing their classification as part of the young stellar disc population.

We obtain constraints in a 12 parameter cosmological model using the recent DESI Data Release (DR) 2 Baryon Acoustic Oscillations (BAO) data, combined with Cosmic Microwave Background (CMB) power spectra (Planck Public Release (PR) 4) and lensing (Planck PR4 + Atacama Cosmology Telescope (ACT) Data Release (DR) 6) data, uncalibrated type Ia Supernovae (SNe) data from Pantheon+ and Dark Energy Survey (DES) Year 5 (DESY5) samples, and Weak Lensing (WL: DES Year 1) data. The cosmological model consists of six $\Lambda$CDM parameters, and additionally, the dynamical dark energy parameters ($w_0$, $w_a$), the sum of neutrino masses ($\sum m_{\nu}$), the effective number of non-photon radiation species ($N_{\textrm{eff}}$), the scaling of the lensing amplitude ($A_{\textrm{lens}}$), and the running of the scalar spectral index ($\alpha_s$). Our major findings are the following: i) With CMB+BAO+DESY5+WL, we obtain the first 2$\sigma$+ detection of a non-zero $\sum m_{\nu} = 0.19^{+0.15}_{-0.18}$ eV (95%). Replacing DESY5 with Pantheon+ still yields a $\sim$1.9$\sigma$ detection. ii) The cosmological constant lies at the edge of the 95% contour with CMB+BAO+Pantheon+, but is excluded at 2$\sigma$+ with DESY5, leaving evidence for dynamical dark energy inconclusive, contrary to claims by DESI collaboration. iii) With CMB+BAO+SNe+WL, $A_{\textrm{lens}} = 1$ is excluded at $>2\sigma$, while it remains consistent with unity without WL data - suggesting for the first time that the existence of lensing anomaly may depend on non-CMB datasets. iv) The Hubble tension persists at 3.6-4.2$\sigma$ with CMB+BAO+SNe; WL data has minimal impact.

Several enigmatic dusty sources have been detected in the central parsec of the Galactic Center. Among them is X7, located at only $\sim$0.02 pc from the central super-massive black hole, Sagittarius A* (Sgr A*). Recent observations have shown that it is becoming elongated due to the tidal forces of Sgr A*. X7 is expected to be fully disrupted during its pericenter passage around 2035 which might impact the accretion rate of Sgr A*. However, its origin and nature are still unknown. We investigated the tidal interaction of X7 with Sgr A* in order to constrain its origin. We tested the hypothesis that X7 was produced by one of the observed stars with constrained dynamical properties in the vicinity of Sgr A*. We employed a set of test-particle simulations to reproduce the observed structure and dynamics of X7. The initial conditions of the models were obtained by extrapolating the observationally constrained orbits of X7 and the known stars into the past, making it possible to find the time and source of origin by minimizing the three-dimensional separation and velocity difference between them. Our results show that ejecta from the star S33/S0-30, launched in $\sim$1950, can to a large extent, replicate the observed dynamics and structure of X7, provided that it is initially elongated with a velocity gradient across it, and with an initial maximum speed of $\sim$600~km~s$^{-1}$. Our results show that a grazing collision between the star S33/S0-30 and a field object such as a stellar mass black hole or a Jupiter-mass object is a viable scenario to explain the origin of X7. Nevertheless, such encounters are rare based on the observed stellar dynamics within the central parsec.

The DESI collaboration, combining their Baryon Acoustic Oscillation (BAO) data with cosmic microwave background (CMB) anisotropy and supernovae data, have found significant indication against $\Lambda$CDM cosmology. The significance of the exclusion of $\Lambda$CDM can be interpreted entirely as significance of the detection of the $\boldsymbol{w_a}$ parameter that measures variation of the dark energy equation of state. We emphasize that DESI's DR2 exclusion of $\Lambda$CDM is quoted in the articles for a combination of BAO and CMB data with each of three different and overlapping supernovae datasets (at 2.8-sigma for Pantheon+, 3.8-sigma for Union3, and 4.2-sigma for DESY5). We show that one can neither choose amongst nor average over these three different significances. We demonstrate how a principled statistical combination yields a combined exclusion significance of 3.1-sigma. Further we argue that, based on available knowledge, and faced with these competing significances, the most secure inference from the DESI DR2 results is the 3.1-sigma level exclusion of $\Lambda$CDM, obtained from combining DESI+CMB alone, while omitting supernovae.

The light curves of radioactive transients, such as supernovae and kilonovae, are powered by the decay of radioisotopes, which release high-energy leptons through $\beta^+$ and $\beta^-$ decays. These leptons deposit energy into the expanding ejecta. As the ejecta density decreases during expansion, the plasma becomes collisionless, with particle motion governed by electromagnetic forces. In such environments, strong or turbulent magnetic fields are thought to confine particles, though the origin of these fields and the confinement mechanism have remained unclear. Using fully kinetic particle-in-cell (PIC) simulations, we demonstrate that plasma instabilities can naturally confine high-energy leptons. These leptons generate magnetic fields through plasma streaming instabilities, even in the absence of pre-existing fields. The self-generated magnetic fields slow lepton diffusion, enabling confinement and transferring energy to thermal electrons and ions. Our results naturally explain the positron trapping inferred from late-time observations of thermonuclear and core-collapse supernovae. Furthermore, they suggest potential implications for electron dynamics in the ejecta of kilonovae. We also estimate synchrotron radio luminosities from positrons for Type Ia supernovae and find that such emission could only be detectable with next-generation radio observatories from a Galactic or local-group supernova in an environment without any circumstellar material.

In the presence of a weak gravitational wave (GW) background, astrophysical binary systems act as high-quality resonators, with efficient transfer of energy and momentum between the orbit and a harmonic GW leading to potentially detectable orbital perturbations. In this work, we develop and apply a novel modeling and analysis framework that describes the imprints of GWs on binary systems in a fully time-resolved manner to study the sensitivity of lunar laser ranging, satellite laser ranging, and pulsar timing to both resonant and nonresonant GW backgrounds. We demonstrate that optimal data collection, modeling, and analysis lead to projected sensitivities which are orders of magnitude better than previously appreciated possible, opening up a new possibility for probing the physics-rich but notoriously challenging to access $\mu\mathrm{Hz}$ frequency GWs. We also discuss improved prospects for the detection of the stochastic fluctuations of ultra-light dark matter, which may analogously perturb the binary orbits.

Motivated by the recent Year-2 data release of the DESI collaboration, we update our results on time-varying dark energy models driven by the Cohen-Kaplan-Nelson bound. The previously found preference of time-dependent dark energy models compared to $\Lambda$CDM is further strengthend by the new data release. For our particular models, we find that this preference increases up to $\approx 2.6\,\sigma$ depending on the used supernova dataset.

International and U.S. strategies and protocols have identified the need to develop rapid-response spacecraft reconnaissance capabilities as a priority to advance planetary defense readiness. A space-based reconnaissance response is recommended for potential impactors as small as 50 m, making these small objects the most likely to trigger a space-based response and the ones that drive the reconnaissance capabilities needed. Even following the successful completion of the NEO Surveyor mission and Rubin Observatory survey efforts, roughly half of the 50-m near-Earth object (NEO) population will remain undiscovered. As a result, 50-m impactors may not be found with long warning times, and a rapid-response flyby mission may be the only reconnaissance possible. To develop a robust flyby reconnaissance capability for planetary defense, four major requirements are defined for a demonstration mission. 1. Enable a flyby of greater than 90 percent of the potential asteroid threat population. 2. Demonstrate the flyby reconnaissance for a 50 m NEO. 3. Obtain the information needed to determine if and where it would impact the Earth. 4. Determine key properties of the asteroid to inform decision makers. As commonly noted in the planetary defense community, in planetary defense, you do not pick the asteroid, the asteroid picks you. Thus, a planetary defense flyby reconnaissance demonstration mission is not about just flying by an asteroid, but rather it is about developing a robust capability for the objects that are most likely to require a short-warning-time, space-based response.

A novel goodness-of-fit strategy is introduced for testing models for angular power spectra characterized by unknown parameters. Using this strategy, it is possible to assess the validity of such models without specifying the distribution of the estimators of the angular power spectrum being used. This holds under general conditions, ensuring the applicability of the method across diverse scenarios. Moreover, the proposed solution overcomes the need for case-by-case simulations when testing different models -- leading to notable computational advantages.

The KM3NeT collaboration recently reported the detection of an ultra-high-energy neutrino event, dubbed KM3-230213A. This is the first observed neutrino event with energy of the order of $\mathcal{O}(100)$PeV, the origin of which remains unclear. We interprete this high energy neutrino event results from the Dirac fermion dark matter (DM) $\chi$ decay through the right-handed (RH) neutrino portal assuming the Type-I seesaw mechanism for neutrino masses and mixings. Fruthermore, dark matter $\chi$ is assumed to charged under $U(1)_X$ dark gauge symmetry, which is sponetaneously broken by the vacuum expectation value of the dark Higgs $\Phi$. In this scenario, the DM can decay into a pair of Standard Model (SM) particles for $v_\Phi \gg m_\chi$, which we assume is the case. If the DM mass is around $440$ PeV with a lifetime $5\times 10^{29}$ sec, it can account for the KM3-230213A event. However, such heavy DM cannot be produced through the thermal freeze-out mechanism due to overproduction and violation of unitarity bounds. We focus on the UV freeze-in production of DM through a dimension-5 operator, which helps in producing the DM dominantly in the early Universe. We have also found a set of allowed parameter values that can correctly account for the DM relic density and decay lifetime required to explain the KM3NeT signal. Moreover, we have generated the neutrino spectra from the two-body decay using the HDMSpectra package, which requires the dark Higgs vacuum expectations value (VEV) to be much larger than the DM mass. Finally, the large value of the dark Higgs field VEV opens up the possibility of generating GW spectra from cosmic strings. We have found a reasonable set of parameter values that can address the KM3NeT signal, yield the correct value of the DM relic density through freeze-in mechanism, and allow for possible detection of GW at future detectors.

Gravitational waves from merging binary black holes present exciting opportunities for understanding fundamental aspects of gravity, including nonlinearities in the strong-field regime. One challenge in studying and interpreting the dynamics of binary black hole collisions is the intrinsically geometrical nature of spacetime, which in many ways is unlike that of other classical field theories. By exactly recasting Einstein's equations into a set of coupled nonlinear Maxwell equations closely resembling classical electrodynamics, we visualize the intricate dynamics of gravitational electric and magnetic fields during inspiral, merger and ring-down of a binary black hole collision.

Space plasmas in various astrophysical setups can often be both very hot and dilute, making them highly susceptible to waves and fluctuations, which are generally self-generated and maintained by kinetic instabilities. In this sense, we have in-situ observational evidence from the solar wind and planetary environments, which reveal not only wave fluctuations at kinetic scales of electrons and protons, but also non-equilibrium distributions of particle velocities. This paper reports on the progress made in achieving a consistent modeling of the instabilities generated by temperature anisotropy, taking concrete example of those induced by anisotropic electrons, such as, electromagnetic electron-cyclotron (whistler) and firehose instabilities. The effects of the two main electron populations, the quasi-thermal core and the suprathermal halo indicated by the observations, are thus captured. The low-energy core is bi-Maxwellian, and the halo is described for the first time by a regularized (bi-)$\kappa$-distribution (RKD), which was recently introduced to fix inconsistencies of standard $\kappa$-distributions (SKD). In the absence of a analytical RKD dispersion kinetic formalism (involving tedious and laborious derivations), both the dispersion and (in)stability properties are directly solved numerically using the numerical Arbitrary Linear Plasma Solver (ALPS). The results have an increased degree of confidence, considering the successful testing of the ALPS on previous results with established distributions.

We present a reanalysis of 17 gravitational-wave events detected with Advanced LIGO and Advanced Virgo in their first three observing runs, using the new IMRPhenomTEHM model -- a phenomenological time-domain multipolar waveform model for aligned-spin black-hole binaries in elliptical orbits with two eccentric parameters: eccentricity and mean anomaly. We also analyze all events with the underlying quasi-circular model IMRPhenomTHM to study the impact of including eccentricity and compare the eccentric and quasi-circular binary hypotheses. The high computational efficiency of IMRPhenomTEHM enables us to explore the impact of two different eccentricity priors -- uniform and log-uniform -- as well as different sampler and data settings. We find evidence for eccentricity in two publicly available LVK events, GW200129 and GW200208_22, with Bayes factors favoring the eccentric hypothesis over the quasi-circular aligned-spin scenario: $\log_{10}\mathcal{B}_{\mathrm{E/QC}}\in\left[1.30^{+0.15}_{-0.15}, 5.14^{+0.15}_{-0.15}\right]$ and $\log_{10}\mathcal{B}_{\mathrm{E/QC}}\in\left[0.49^{+0.08}_{-0.08}, 1.14^{+0.08}_{-0.08}\right]$, respectively. Additionally, the two high-mass events GW190701 and GW190929 exhibit potential eccentric features. For all four events, we conduct further analyses to study the impact of different sampler settings. We also investigate waveform systematics by exploring the support for spin precession using IMRPhenomTPHM and NRSur7dq4, offering new insights into the formation channels of detected binaries. Our results highlight the importance of considering eccentric waveform models in future observing runs, alongside precessing models, as they can help mitigate potential biases in parameter estimation studies. This will be particularly relevant with the expected increase in the diversity of the binary black hole population with new detectors.

We describe an exact solution representing a bouncing cosmology in the Minimal Exponential Measure (MEMe) model. Such a solution, obtained by means of the linearization around small values of the characteristic energy scale q of the theory, has the peculiarity of representing a complete bounce model that can be used to explore quantitative processes in non-singular cosmologies.

This study evaluates the possibility of efficient radio emission generation in the bow shock region of hot Jupiter-type exoplanets. As a source of energetic electrons, the shock drift acceleration mechanism at a quasi-perpendicular shock is proposed. Electrons reflected and accelerated by the shock propagate through the relatively dense stellar wind plasma and excite plasma waves; therefore, a plasma emission mechanism is considered as the source of the resulting radio waves. Using the bow shock of the hot Jupiter HD 189733b as a case study, the properties of the energetic electron beam, the excited plasma waves, and the resulting radio frequencies are estimated. An energy-based analysis is carried out to identify the range of stellar wind parameters for which radio emission from the bow shock of the exoplanet HD 189733b could be detectable by modern astronomical instruments.

Lorentz-invariance violation (LV) at energy scales approaching the Planck regime serves as a critical probe for understanding quantum gravity phenomenology. Astrophysical observations of gamma-ray bursts (GRBs) present a promising avenue for testing LV-induced spectral lag phenomena; however, interpretations are complicated by degeneracies between LV effects and intrinsic emission delays. This study systematically investigates three competing time delay models: Model A (LV delay combined with a constant intrinsic delay), Model B (energy-dependent intrinsic delay without LV), and Model C (LV delay combined with energy-dependent intrinsic delay). We utilize mock GRB datasets generated under distinct delay mechanisms and employ Bayesian parameter estimation on simulated observations of 10 GRBs. Our findings demonstrate that Model C consistently recovers input parameters across all datasets. In contrast, Models A and B struggle to reconcile data generated under alternative mechanisms, particularly when confronted with high-energy TeV photons from GRB 190114C and GRB 221009A. Our analysis confirms that the incorporation of energy-dependent intrinsic delays in Model C is essential for establishing robust LV constraints, effectively resolving prior ambiguities in the interpretation of multi-GeV and TeV photon emissions. The results validate Model C as a generalized framework for future LV searches, yielding a subluminal LV scale of \(E_{\rm LV} \simeq 3 \times 10^{17}\) GeV based on realistic datasets. These findings are consistent with earlier constraints derived from Fermi-LAT datasets. This work underscores the necessity for joint modeling of LV and astrophysical emission processes in next-generation LV studies utilizing observatories such as LHAASO and CTA.

Multi natural inflation is studied in the context of warm inflation. We study the warm multi natural inflation scenario with both linear and cubic dissipation coefficients. The model is motivated by axion-like inflation models with coupling to non-Abelian gauge fields through a dimension five coupling and dissipation originating from sphaleron decay in a thermal bath. Both cases of dissipation coefficients can be compatible with current observations. In the case of the cubic dissipation coefficient, we find that the curvature perturbation starts to grow suddenly when a transition from a weak dissipation to a strong dissipation regime occurs at the later stage of the inflation. We also show that such rapid growth of the curvature perturbation on small scales gives rise to abundant scalar induced gravitational waves, which may be detectable with future gravitational wave detectors such as DECIGO and ET. On the other hand, there are also other parameter regions of the model, in the warm inflation regime of weak to strong dissipation and with sub-Planckian axion decay constant, that can lead to overproduction of primordial black holes on small scales, which are constrained by nucleosynthesis bounds, thus ruling out the model in this region of parameters.

Using $10,\!080^3$ grid simulations, we analyze scale-dependent alignment in driven, compressible, no net-flux magnetohydrodynamic turbulence. The plasma self-organizes into localized, strongly aligned regions. Alignment spans all primitive variables and their curls. Contrary to incompressible theory, velocity-magnetic alignment scales as $\theta(\lambda) \sim \lambda^{1/8}$, where $\lambda$ is the scale, suggesting a distinct three-dimensional eddy anisotropy and a much higher critical transition scale toward a reconnection-mediated cascade.

We analyze the damping of inflationary gravitational waves (GW) that re-enter the Hubble horizon before or during a post-inflationary era dominated by a meta-stable, right-handed neutrino (RHN), whose out-of-equilibrium decay releases entropy. Within a minimal type-I seesaw extension of the Standard Model (SM), we explore the conditions under which the population of thermally produced RHNs remain long-lived and cause a period of matter-domination. We find that the suppression of the GW spectrum occurs above a characteristic frequency determined by the RHN mass and active-sterile mixing. For RHN masses in the range $0.1$ - $10$ GeV and mixing $10^{-12} \lesssim |V_{eN}|^2 \lesssim 10^{-5}$, we estimate such characteristic frequencies and the signal-to-noise ratio to assess the detection prospects in GW observatories such as THEIA, $\mu$-ARES, LISA, BBO and ET. We find complementarity between GW signals and laboratory searches in SHiP, DUNE and LEGEND-1000. Notably, RHN masses of $0.2$ - $2$ GeV and mixing $10^{-10} \lesssim |V_{eN}|^2 \lesssim 10^{-7}$ are testable in both laboratory experiments and GW observations. Additionally, GW experiments can probe the canonical seesaw regime of light neutrino mass generation, a region largely inaccessible to laboratory searches.

We examine the impact of non-perturbative quantum corrections to the entropy of both charged and charged rotating quasi-topological black holes, with a focus on their thermodynamic properties. The negative-valued correction to the entropy for small black holes is found to be unphysical. Furthermore, we analyze the effect of these non-perturbative corrections on other thermodynamic quantities, including internal energy, Gibbs free energy, charge density, and mass density, for both types of black holes. Our findings indicate that the sign of the correction parameter plays a crucial role at small horizon radii. Additionally, we assess the stability and phase transitions of these black holes in the presence of non-perturbative corrections. Below the critical point, both the corrected and uncorrected specific heat per unit volume are in an unstable regime. This instability leads to a first-order phase transition, wherein the specific heat transitions from negative to positive values as the system reaches a stable state.

Neutron stars offer powerful astrophysical laboratories to probe the properties of dark matter. Gradual accumulation of heavy, non-annihilating dark matter in neutron stars can lead to the formation of comparable-mass black holes, and non-detection of gravitational waves from mergers of such low-mass black holes can constrain such dark matter interactions with nucleons. These constraints, though dependent on the currently uncertain binary neutron star merger rate density, are significantly more stringent than those from direct detection experiments and provide some of the strongest limits on heavy, non-annihilating dark matter interactions. Additionally, dark matter with baryon number-violating interactions can induce excess heating in cold neutron stars and is thus significantly constrained by thermal observations of cold neutron stars.

The natural environment of the Earth can act as a sensitive detector for dark matter in ultralight axions. When axions with masses between $1\times10^{-15}\,{\rm eV}$ and $1\times10^{-13}\,{\rm eV}$ pass through the Earth, they interact with the global geomagnetic field, generating electromagnetic (EM) waves in the extremely low-frequency range ($0.3$--$30\,{\rm Hz}$) through axion-photon coupling. This paper is one of a series of companion papers for~\cite{Taruya:2025zql}, focusing on the data analysis method and search results for an axion signal. Utilizing the theoretical predictions of axion-induced EM spectra from a companion study, we analyzed long-term observational data of terrestrial magnetic fields in this frequency band to search for axion-induced signals. Our analysis identified 65 persistent signal candidates with a signal-to-noise ratio (SNR) greater than 3. Aside from these candidates, we placed a new upper bound on the axion-photon coupling parameter, significantly refining the previous constraint from CAST by at most two orders of magnitude down to $g_{a\gamma} \lesssim 4\times10^{-13} \,{\rm GeV}^{-1}$ for the axion mass around $3 \times 10^{-14}\,{\rm eV}$.

Galaxy formation models, particularly semi-analytic models (SAMs), rely on differential equations with free parameters to describe the physical mechanisms governing galaxy formation and evolution. Traditionally, most SAMs calibrate these parameters manually to match observational data. However, this approach fails to fully explore the multidimensional parameter space, resulting in limited robustness and inconsistency with some observations. In contrast, the L-Galaxies SAM features a unique Markov Chain Monte Carlo (MCMC) mode, enabling robust model calibration. Using this functionality, we address a long-standing tension in galaxy formation models: simultaneously reproducing the number densities of dusty star-forming galaxies (DSFGs) and high-redshift massive quiescent galaxies (MQs). We test nine combinations of observational constraints - including stellar mass functions, quiescent fractions, neutral hydrogen mass functions, and DSFG number densities - across different redshifts. We then analyze the resulting galaxy property predictions and discuss the underlying physical mechanisms. Our results identify a model that reasonably matches the number density of DSFGs while remaining consistent with observationally-derived lower limits on the number density of high-redshift MQs. This model requires high star formation efficiencies in mergers and a null dependency of supermassive black hole (SMBH) cold gas accretion on halo mass, facilitating rapid stellar mass and SMBH growth. Additionally, our findings highlight the importance of robust calibration procedures to address the significant degeneracies inherent to multidimensional galaxy formation models.

The Roman Space Telescope Galactic Bulge Time Domain Survey (GBTDS) is expected to detect ~10^5 transiting planets. Many of these planets will have short orbital periods and are thus susceptible to tidal decay. We use a catalog of simulated transiting planet detections to predict the yield of orbital decay detections in the Roman GBTDS. Assuming a constant stellar tidal dissipation factor, Q^{'}_{*}, of 10^6, we predict ~ 5 - 10 detections. We additionally consider an empirical period-dependent parameterization of Q^{'}_{*} \propto P^{-3} and find a substantially suppressed yield. We conclude that Roman will provide constraints on the rate of planet engulfment in the Galaxy and probe the physics of tidal dissipation in stars.

Recent measurements of baryon acoustic oscillations (BAO) by the Dark Energy Spectroscopic Instrument (DESI) exhibit a mild-to-moderate tension with cosmic microwave background (CMB) and Type Ia supernova (SN) observations when interpreted within a flat $\Lambda$CDM framework. This discrepancy has been cited as evidence for dynamical dark energy (DDE). Given the profound implications of DDE for fundamental physics, we explore whether the tension can instead be resolved by modifying the physics of recombination. We find that a phenomenological model of modified recombination can effectively reconcile the BAO and CMB datasets and, unlike DDE, also predicts a higher Hubble constant $H_0$, thereby partially alleviating the Hubble tension. A global fit to BAO, CMB, and calibrated SN data clearly favors modified recombination over DDE, suggesting that current claims of a DDE detection may be premature.

Weak gravitational lensing is the slight distortion of galaxy shapes caused primarily by the gravitational effects of dark matter in the universe. In our work, we seek to invert the weak lensing signal from 2D telescope images to reconstruct a 3D map of the universe's dark matter field. While inversion typically yields a 2D projection of the dark matter field, accurate 3D maps of the dark matter distribution are essential for localizing structures of interest and testing theories of our universe. However, 3D inversion poses significant challenges. First, unlike standard 3D reconstruction that relies on multiple viewpoints, in this case, images are only observed from a single viewpoint. This challenge can be partially addressed by observing how galaxy emitters throughout the volume are lensed. However, this leads to the second challenge: the shapes and exact locations of unlensed galaxies are unknown, and can only be estimated with a very large degree of uncertainty. This introduces an overwhelming amount of noise which nearly drowns out the lensing signal completely. Previous approaches tackle this by imposing strong assumptions about the structures in the volume. We instead propose a methodology using a gravitationally-constrained neural field to flexibly model the continuous matter distribution. We take an analysis-by-synthesis approach, optimizing the weights of the neural network through a fully differentiable physical forward model to reproduce the lensing signal present in image measurements. We showcase our method on simulations, including realistic simulated measurements of dark matter distributions that mimic data from upcoming telescope surveys. Our results show that our method can not only outperform previous methods, but importantly is also able to recover potentially surprising dark matter structures.

JWST have revealed temporarily-quenched and ultraviolet-luminous galaxies in the early universe, suggesting enhanced star formation stochasticity. Verifying this hypothesis is critical, yet challenging; outshining, wherein light from young stars dominates the spectral energy distribution, represents perhaps the greatest challenge in inferring the formation histories of unresolved galaxies. In this paper, we take a simple model of burstiness and show that state-of-the-art inference methods with flexible star formation histories (SFHs) and neutral priors, while recovering average star formation rates (SFRs; $\sim0.1$ dex median offset), fail to recover the complexities of fluctuations on tens of Myr timescales, and typically underestimate masses in bursty systems ($\sim0.15$ dex). Surprisingly, detailed SFH recovery is still sensitive to priors even when data quality is optimal, e.g., including high signal-to-noise ($\rm20~pixel^{-1}$) spectroscopy with wide coverage (rest-frame $0.12-1.06~\mu$m). Crucially, however, refitting the same data with a prior correctly encoding the bursty expectation eliminates these biases: median offsets in mass and SFRs decrease to $\sim 0.04$ dex and $\sim 0.05$ dex, respectively. Under the assumption that current population burstiness predicts past SFH, the solution to outshining in modeling statistical samples is empirically measuring recent galaxy SFHs with population modeling. A prototype is H$\alpha$/UV: while helpful, it is insufficient to constrain the expected complex burstiness. To this end, we introduce a more complete, quantitative population-level approach and demonstrate that it promises to recover the typical amplitude, timescale, and slope of the recent SFH to high accuracy. This approach thus has the strong potential to solve outshining using observations from JWST.

Compact Obscured Nuclei (CONs) are heavily obscured infrared cores that have been found in local (ultra)luminous infrared galaxies (U/LIRGs). They show bright emission from vibrationally excited rotational transitions of HCN, known as HCN-vib, and are thought to harbor Compton Thick (CT, $N_{\text{H}} \geq 10^{24}$ cm$^{-2}$) active galactic nuclei (AGN) or extreme compact starbursts. We explore the potential evolutionary link between CONs and CT AGN by searching for CONs in hard X-ray-confirmed CT AGN from the Great Observatories All-sky LIRG Survey (GOALS). Here, we present new Atacama Large Millimeter/submillimeter Array Band 6 observations that targeted HCN-vib emission in four hard X-ray-confirmed CT AGN. We analyze these objects together with literature HCN-vib measurements of five additional hard X-ray-confirmed CT AGN from the GOALS sample. We do not detect any CONs in this combined sample of nine CT AGN. We then explore a proposed evolutionary sequence in which CONs evolve into X-ray-detectable CT AGN once outflows and feedback reduce the column densities of the enshrouding gas. We find, however, no evidence of well-developed dense molecular outflows in the observed CT AGN. While this could suggest that CT AGN are not universally linked to CONs, it could also be explained by a short duty cycle for molecular outflows.

We characterize the warm circumgalactic medium (CGM) of a dwarf galaxy pair with properties similar to the Magellanic Clouds in the \textsc{Hestia} cosmological simulations. The system consists of a massive dwarf ($M_{\rm halo} \sim 10^{11.5} M_{\odot}$) and a lower-mass companion ($M_{\rm halo} \sim 10^{10} M_{\odot}$), dynamically evolving in isolation before infall into a Milky Way-mass halo. The massive dwarf hosts a warm coronal gas envelope with a temperature of $T \sim 3 \times 10^5$ K, consistent with expectations for virialized CGM in dwarf halos. Tidal interactions produce a neutral gas stream that extends over $\sim 150$ kpc, with an \ion{H}{1} mass of $M_{\rm HI} \sim 10^8 M_{\odot}$, similar to the Magellanic Stream. Furthermore, in the \textsc{Hestia} simulation suite, we find that coronal gas is ubiquitous in all halos with $M_{\rm halo} > 10^{11} M_{\odot}$, implying that massive dwarfs generically develop extended gaseous envelopes prior to accretion. This result has significant implications for the survival of neutral tidal structures, and suggests that current and future high-ion UV absorption-line observations are indicative of warm coronae surrounding LMC-mass dwarfs, independent of their environment.

A fundamental question in cosmology is whether dark energy evolves over time, a topic that has gained prominence since the discovery of cosmic acceleration. Recently, the DESI collaboration has reported increasing evidence for evolving dark energy using combinations of cosmic microwave background (CMB), type Ia supernova (SN), and their new measurements of baryon acoustic oscillations (BAO). However, our analysis reveals that these combinations are problematic due to clear tensions among the CMB, BAO and SN datasets. Consequently, DESI's claim of dynamical dark energy (DDE) is not robust. A more reliable approach involves constraining the evolution of dark energy using each dataset independently. Through a statistical comparison for each dataset, on average, we find that DDE is strongly preferred over the $\Lambda$CDM model. This suggests that DDE likely exists, although its real parameter space remains elusive due to weak constraints on the dark energy equation of state and inconsistencies among the datasets. Interestingly, when considering DDE, none of the individual datasets -- including CMB, DESI DR2, Pantheon+, Union3, and DESY5 -- can independently detect cosmic acceleration at a significant level. Our findings not only clarify the current understanding of the nature of dark energy but also challenge the established discovery of cosmic acceleration and the long-held notion that dark energy exerts negative pressure. Both individual and combined datasets suggest that the ultimate fate of the universe is likely to be dominated by matter rather than dark energy.

The latest ACT data release disfavors the attractor $n_s=1-2/N$. In inflationary models with nonminimal coupling, such attractors typically arise in the strong coupling limit. To align with observational constraints, we focus on nonminimal coupling models with small coupling constants. For the model with the coupling function $\Omega(\phi) = 1 + \xi f(\phi)$ and the potential $V(\phi) = \lambda^2 f^2(\phi)$, we find that observational data constrain the parameters as $0.1 \lesssim \xi \lesssim 35$ and $0 \lesssim k \lesssim 1.5$ for $f(\phi) = \phi^k$ at the $1\sigma$ confidence level. With the help of the nonmiminal coupling $\Omega(\phi) = 1 + \xi \phi^2$, the hilltop inflation and power-law inflation models with power indices $2/3$ and $1/3$ can be consistent with observational data within the $1\sigma$ range. We also give the viable parameter regions for $\xi$ for these three models.

Recent data from DESI, in combination with other data, provide moderate evidence of dynamical dark energy, $w\neq-1$. In the $w_0, w_a$ parametrization of $w$, there is a preference for a phantom crossing, $w<-1$, at redshift $z\sim0.5$. In general relativity, the phantom equation of state is unphysical. Thus it is important to check whether phantom crossing is present in other physically self-consistent models of dark energy that have equivalent evidence to the $w_0, w_a$ parametrization. We find that thawing quintessence with nonzero cosmic curvature can fit the recent data as well as $w_0, w_a$ in a flat background, based on both parametric and realistic scalar field evolutions. Although the realistic model does not allow $w<-1$, the parametrizations do allow it. However even if we allow $w<-1$ the data do not enforce phantom crossing. Thus, the phantom crossing is an artifact of a parametrization that is not based on a physical model.

We present a Simulation-Based Inference (SBI) framework for cosmological parameter estimation via void lensing analysis. Despite the absence of an analytical model of void lensing, SBI can effectively learn posterior distributions through forward modeling of mock data. We develop a forward modeling pipeline that accounts for both cosmology and the galaxy-halo connection. By training a neural density estimator on simulated data, we infer the posteriors of two cosmological parameters, $\Omega_m$ and $S_8$. Validation tests are conducted on posteriors derived from different cosmological parameters and a fiducial sample. The results demonstrate that SBI provides unbiased estimates of mean values and accurate uncertainties. These findings highlight the potential to apply void lensing analysis to observational data even without an analytical void lensing model.

This work investigates a potential time dependence of the absolute magnitude of Type Ia Supernovae (SN Ia). Employing the Gaussian Process approach, we obtain the SN Ia absolute magnitude and its derivative as a function of redshift. The data set considered in the analysis comprises measurements of apparent magnitude from SN Ia, Hubble rate from cosmic chronometers, and the ratio between angular and radial distances from Large-Scale Structure data (BAO and voids). Our findings reveal good compatibility between the reconstructed SN Ia absolute magnitudes and a constant value. However, the mean value obtained from the Gaussian Process reconstruction is $M=-19.456\pm 0.059$, which is $3.2\sigma$ apart from local measurements by Pantheon+SH0ES. This incompatibility may be directly associated to the $\Lambda$CDM model and local data, as it does not appear in either model-dependent or model-independent estimates of the absolute magnitude based on early universe data. Furthermore, we assess the implications of a variable $M$ within the context of modified gravity theories. Considering the local estimate of the absolute magnitude, we find $\sim3\sigma$ tension supporting departures from General Relativity in analyzing scenarios involving modified gravity theories with variations in Planck mass through Newton's constant.

Fast Radio Bursts (FRBs) have emerged as a powerful tool for cosmological studies, particularly through the dispersion measure-redshift ($\mathrm{DM}-z$) relation. This work proposes a novel calibration method for FRBs using the Yang-Li-Zhang (YLZ) empirical relation, which links the rotation measure (RM) of FRBs to the luminosity of their associated persistent radio sources (PRS). We demonstrate that this approach provides independent constraints on cosmological parameters, bypassing limitations inherent to traditional $\mathrm{DM}-z$ method. Utilizing the current sample of four YLZ-calibrated FRBs, we derive a Hubble constant measurement of $H_0 = 86.18_{-14.99}^{+18.03}\ \mathrm{km\ s^{-1}\ Mpc^{-1}}$ (68\% CL). Monte Carlo simulations indicate that a future catalog of 400 FRB-PSR systems could reduce the relative uncertainty of $H_0$ to 4.5\%. Combining YLZ-calibrated FRBs with $\mathrm{DM}-z$ sample reveals critical synergies: joint analysis of equalized samples ($N=100$ for both methods) reduces the relative uncertainty of $H_0$ to 2.9\%, mainly because the incorporation of PRS observations substantially mitigates the degeneracy between the parameters such as IGM baryon mass fraction ($f_{\rm IGM}$) and other cosmological parameters inherent to the $\mathrm{DM}-z$ relation.

A search was carried out for pulsars with periods (P) from 2 to 90 s in daily observations carried out over an interval of 5 years in a area measuring 6300 sq.deg. The data was obtained on a Large Phased Array (LPA) at a frequency of 111 MHz. The periodograms calculated using the Fast Folding Algorithm (FFA) were used for the search. To increase the sensitivity, the periodograms obtained in different observation sessions were added together. Of the 14 known pulsars that entered the study area, with periods of P>2 s and dispersion measures (DM) less than 200 pc/cm$^3$, 9 were detected. 2 new pulsars have been found. The mean profiles of pulsars are obtained and estimates of their flux densities are given. The open pulsar J1951+28, with a period of P = 7.3342 s and DM = 3.5 pc/cm$^3$, turned out to be one of the pulsars closest to the Sun. The absence of new pulsars with periods of tens of seconds with a search sensitivity of 1 mJy outside the Galactic plane indicates a low probability of the existence of pulsars with extremely long periods. Most likely, the recently found sources of periodic radiation with periods from a minute to tens of minutes are white dwarfs.

We present multiwavelength analysis of the pre-flare phase and onset of the powerful X4.9 near-limb eruptive solar flare on February 25, 2014, revealing the tether-cutting (TC) geometry. We aim at determining relationship between the region of pre-flare energy release with the regions where the flare started to develop, and to investigate a detailed chronology of energy release during the pre-flare time interval and the beginning of the impulse phase. Using X-ray, ultraviolet and radio microwave data we found that the pre-flare energy release site was compact and localized in the vicinity of TC interaction of magnetic structures near the polarity inversion line. The analysis indicates that a pre-flare current sheet (CS) could be in this region. Good correspondence between the location of the pre-flare and flare emission sources visible at the very beginning of the impulsive phase is shown. We found relationship between dynamics of the energy release in the pre-flare CS and formation of the future flare eruptive structure. The growth of the magnetic flux rope was associated with activation of plasma emissions, flows and an increase of UV radiation fluxes from the region where the pre-flare CS was located. The eruptive flux rope gradually grew due to feeding by magnetized plasma ejected from the reconnecting pre-flare CS. Finally, it is shown that the most probable trigger of the eruption was a local fast microflare-like magnetic reconnection in the pre-flare CS. Some local instability in the pre-flare sheet could lead to a transition from the slow to fast reconnection regime. As a result, an ejection from the sheet was initiated and the eruptive flux rope lost its stability. Then, the eruptive flux rope itself initiated formation of the main reconnecting flare CS as in the Standard Flare Model during its movement, and intense emissions associated with the impulsive phase were observed.

The 21-cm forest offers a powerful cosmological probe of the thermal history and small-scale structure of the intergalactic medium during the Epoch of Reionization (EoR). Its success, however, critically depends on the availability of high-redshift radio-loud quasars (HzRLQs) as background sources. In this work, we investigate the configuration requirements for a Moon-based low-frequency radio interferometer aimed at maximizing the detection of HzRLQs for future 21-cm forest studies. Building upon a previously developed quasar luminosity function (QLF), we forecast HzRLQ abundances under various array configurations. Assuming a total survey area of $10^4\,\mathrm{deg}^2$ and 1 year of observation, we compare continuum surveys with 10 MHz bandwidth and 21-cm forest surveys with 5 kHz resolution. Our results show that a minimum collecting area of $\sim$6 500 m$^2$ enables detection at $z \sim 6$, while SKA-like arrays ($N_{\mathrm{st}} = 512$) extend the detection limit to $z \sim 10$ for 21-cm forest survey and $z \sim 16$ for continuum survey. Larger arrays with $N_{\mathrm{st}} = 2048$ can reach $z \sim 11$ in 21-cm forest mode. We also explore configurations that maintain fixed collecting areas while increasing the number to enhance survey efficiency. This boosts source detection but significantly increases the data volume and computational demands. These results underscore the importance of optimizing array design for different survey goals and balancing sensitivity, spectral resolution, and data management. A well-designed Moon-based array could open a new observational window on reionization and early cosmic structure formation.

Filaments are special plasma phenomena embedded in the solar atmosphere, characterized by unique thermodynamic properties and magnetic structures. Magnetohydrodynamic (MHD) simulations are useful to investigate the eruption mechanisms of filaments. We conduct a data-constrained zero-$\beta$ MHD simulation in spherical coordinates to investigate a C3.5 class flare triggered by an eruptive filament on 2022 August 15 in a decaying weak active region 13079. We reconstruct the three-dimensional coronal magnetic field using vector magnetograms and synoptic maps from the Solar Dynamics Observatory/Helioseismic and Magnetic Imager (SDO/HMI). We transform vector magnetic field into Stonyhurst heliographic spherical coordinates combined with a synoptic map and constructed a potential field source surface (PFSS) model with a magnetic flux rope (MFR) embedded using the Regularized Biot--Savart Laws (RBSL). Subsequently, we conduct a spherical zero-$\beta$ MHD simulation using the Message Passing Interface Adaptive Mesh Refinement Versatile Advection Code (MPI-AMRVAC) and replicated the entire dynamic process of the filament eruption consistent with observations. With the calculation of time-distance profile, Qusai-Separatrix Layers (QSL), and synthetic radiation from simulated current density, we find a good agreement between our simulation and observations in terms of dynamics and magnetic topology. Technically, we provide a useful method of advanced data-constrained simulation of weak active regions in spherical coordinates. Scientifically, the model allows us to quantitatively describe and diagnose the entire process of filament eruption.

Potential vibrational modes associated with diffuse interstellar bands (DIBs) could be discerned by examining energy differences between correlated DIBs. Consequently, $\approx 10^3$ higher correlated DIB pairs ($r-\sigma_r \ge 0.8$, $\ge 12$ sightlines) were extracted from the Apache Point Observatory DIB catalog, and their energy spacings computed. In this first macro exploratory step, a histogram possibly reveals chemical bond signatures of C$\equiv$C, C$\equiv$N, S$-$H, C$-$O, C$=$O, Si$-$H, N$-$H, C$-$H (aliphatic), C$\mathbf{^{\underline{...}}}$C (in-ring), and aromatics (C$-$H stretch, C$\mathbf{^{\underline{...}}}$C in-ring, oop C$-$H bending, and overtones). Continued research is required to (in)validate the histogram approach, mitigate noise, scrutinize maxima, break degeneracies, and converge upon an optimal framework.

$\delta$ Scuti ($\delta$ Sct) stars are potential distance tracers for studying the Milky Way structure. We conduct a comprehensive analysis of the period-luminosity (PL) and period-luminosity-metallicity (PLZ) relation for $\delta$ Sct stars, integrating data from the Zwicky Transient Facility (ZTF), the Transiting Exoplanet Survey Satellite (TESS), Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST), Apache Point Observatory Galactic Evolution Experiment (APOGEE), and Gaia. To mitigate the impact of the Gaia parallax zero point offset, we applied a correction method, determining the optimal zero point value to be $zp_\varpi = 35 \pm 2 \, \mu\text{as}$. Using the three best bands, by varying the parallax error threshold, we found that the total error of the PLR zero point was minimized to 0.9\% at a parallax error threshold of 6\%. With this threshold, we derived the PL and PLZ relation for nine bands (from optical to mid-infrared) and five Wesenheit bands. Through our analysis, we conclude that the influence of metallicity on the PLR of $\delta$ Sct stars is not significant, and the differences across various bands are minimal.

Slow magnetoacoustic waves (SMAWs) have been considered in the past as a possible candidate for chromospheric heating. This study analyzes 20 active regions observed between 2012 and 2016 to examine the amplitude and energy flux variation of SMAWs in the umbral atmosphere. Six different wavelength channels from the Atmospheric Imaging Assembly onboard the Solar Dynamics Observatory, covering regions from the photosphere to the low corona, were utilized for this purpose. The wave amplitude estimations show a gradual increase in 3-minute oscillation amplitude, peaking between 700--900 km, followed by a steady decrease; at altitudes greater than 1800 km, the amplitude appears to increase and then decrease again. The corresponding energy flux, on the other hand, displays a steady and monotonous decrease with a significant reduction in value from approximately $3.32 \pm 0.50~\mathrm{kW,m^{-2}}$ near the photosphere to about $(6.47 \pm 3.16) \times 10^{-4}~\mathrm{W,m^{-2}}$ at an altitude of 2585 km. This decay may be attributed to radiative damping and shock dissipation in the lower altitudes, and thermal conduction and viscosity in the higher altitudes. The missing flux is a factor of 3--15 lower than that required to counterbalance the chromospheric radiative losses.

We report on the spectral energy distributions (SEDs) of infrared-bright dust-obscured galaxies (DOGs) with $(i - [22])_{\rm AB} \geq 7.0$. Using photometry from the deep and wide Ultraviolet Near-Infrared Optical Northern Survey, combined with near-IR and mid-IR data from the UKIRT Infrared Deep Sky Survey and the Wide-field Infrared Survey Explorer, we successfully identified 382 DOGs in $\sim$ 170 deg$^2$. Among them, the vast majority (376 DOGs) were classified into two subclasses: bump DOGs (132/376) and power-law (PL) DOGs (244/376), which are dominated by star formation and active galactic nucleus (AGN), respectively. Through the SED analysis, we found that roughly half (120/244) of the PL DOGs show ''broken'' power-law SEDs. The significant red slope from optical to near-IR in the SEDs of these ''broken power-law DOGs'' (BPL DOGs) probably reflects their large amount of dust extinction. In other words, BPL DOGs are more heavily obscured AGNs, compared to PL DOGs with non-broken power-law SEDs.

The prompt emission of gamma-ray bursts (GRBs) is supposed to be released from the relativistic jet launched from the central engine. Apart from the non-thermal nature of the spectra in a majority of GRBs, there is evidence for the presence of quasi-thermal components in the prompt emission of a few GRBs according to observations by Fermi satellite. On the other hand, the GRB jet has been revealed as structured in recent research. The theoretical observed spectra of photosphere emissions by an off-axis observer and the dependence of the spectra on the viewing angle under the assumption of structured jets remain unexplored. In this paper, we numerically calculate the instantaneous photosphere spectra by different viewing angles from a structured jet, from which relevant temporal and spectral characteristics are derived. Moreover, we address the necessity of proper treatment of the outflow boundary in the photosphere emission scenario. Furthermore, our calculations suggest that the Einstein Probe and Space-based multi-band astronomical Variable Object Monitor will have the capability to detect the short GRBs similar to GRB 170817A up to a luminosity distance of 200Mpc if the off-axis viewing angle is less than 10 degrees.

The eruption of solar prominences can eject substantial mass and magnetic field into interplanetary space and cause geomagnetic storms. However, various questions about prominences and their eruption mechanism remain unclear. In particular, what causes the intriguing Doppler bullseye pattern in prominences has not yet been solved, despite some preliminary studies proposing that they are probably associated with counterstreaming mass flows. Previous studies are mainly based on single-angle and short timescale observations, making it difficult to determine the physical origin of Doppler bullseye patterns in prominences. Here, taking advantage of stereoscopic observations taken by the Solar Dynamics Observatory and the Solar Terrestrial Relations Observatory and a three-dimensional numerical simulation, we investigate the origin of prominence Doppler bullseye pattern by tracing a long-lived transequatorial filament/prominence from July 23 to August 4, 2012. We find that repeated coronal jets at one end of the prominence can launch the Doppler bullseye pattern. It is evidenced in our observations and simulation that during the forward traveling of jet plasma along the helical magnetic field structure of the prominence, part of the ejecting plasma can not pass through the apex of the prominence due to the insufficient kinetic energy and therefore forms a backward-moving mass flow along the same or neighboring magnetic field lines. This process finally forms counterstreaming mass flows in on-disk filaments. When the on-disk filament rotates to the solar limb to be a prominence, the counterstreaming mass flows are naturally observed as a Doppler bullseye pattern.

Interstellar hydrogen atoms (H atoms) penetrate into the heliosphere through the region of the solar wind interaction with the interstellar plasma due to their large mean free path. Resonant charge exchange of H atoms with protons has been considered as the main interaction process between the components. In the majority of models, other processes like elastic H-H and H-p collisions are not included. Moreover, it has been assumed that the velocities of the colliding particles remain unchanged during charge exchange. This corresponds to the scattering on the angle of $\pi$ in the centre mass rest frame. The goal of this paper is to explore effects of the elastic H-H and H-p collisions as well as the angular scattering during charge exchange on the distribution of the interstellar atoms in the heliosphere and at its boundary. We present results of simple (and therefore, easily repeatable) kinetic model of the interstellar atom penetration through the region of the solar and interstellar winds interaction into the heliosphere. As a result of the model we compute the distribution function of the interstellar atoms at different heliospheric distances. Further, this distribution function is used to compute its moments and potentially observable features such as absorption and backscattered spectra in the Lyman-alpha line. Results show that there are differences in the behavior of the distribution function when considering elastic collisions and the changes in the moments of the distribution achieve 10%. Therefore, in cases where precise calculation of H atom parameters is essential, such as in the modeling of backscattered Lyman-$\alpha$ emission, elastic collisions must be considered.

We use the highest-resolution EAGLE simulation, Recal-L025N0752, to study the properties and formation of ultra-diffuse galaxies (UDGs). We identify 181 UDGs and find their properties closely match observations. The total masses of EAGLE UDGs range from ${\sim}5\times 10^{8}~M_{\odot}$ to ${\sim}2\times 10^{11}~M_{\odot}$, indicating that they are dwarf galaxies rather than failed $L_\star$ galaxies. EAGLE UDGs are not a distinct population, but rather a subset of dwarf galaxies, as their properties generally form a continuous distribution with those of normal dwarf galaxies. Unlike the situations in previous studies, the extended sizes of field UDGs in EAGLE are not driven by high halos spin or by supernova-induced stellar expansion, but instead largely arise from high spins in their star-forming gas and thus the newly formed stars at large radii. This might be attributed to galactic fountains, by which star-forming gas are launched to large halo-centric distances and acquire additional angular momentum through interactions with the circumgalactic medium. For satellite UDGs, ${\sim} 60 \%$ of them were already UDGs before falling into the host galaxy, while the remaining ${\sim} 40\%$ were normal galaxies prior to infall and subsequently transformed into UDGs due to tidal effects after infall.

Laboratory searching for dark matter is crucial for understanding several fundamental conundrums in physics and cosmology. Most cavity-based haloscope searches focus on the frequency range below 10 GHz, while the parameter space with higher frequency remains rarely explored, due to the challenges lying in the fabrication of microwave cavities. Here we report the first Q-band haloscope searching for dark photons with a 33.141 GHz cavity. A novel coupling tuning structure separated from the cavity was designed so as not to degrade the quality factor of the cavity. We have established the most stringent constraints $\chi<2.5\times10^{-12}$ at a confidence level of 90$\%$ in the frequency range from 33.139 GHz to 33.143 GHz, corresponding to the mass of dark photons ranging from 137.05 $\mu$eV to 137.07 $\mu$eV. The results surpass the previous astronomical constraints by nearly three orders of magnitude. This work has demonstrated the feasibility of dark matter haloscopes at Q band. In the future, the constraints can be further improved by more than one order of magnitude through low-temperature experiments, and the setup can be extended to search for axions, axion-like particles, and high-frequency gravitational waves.

We study the G013.313+0.193 G013.313 region, a complex environment characterized by molecular cloud interactions indicative of cloud-cloud collision (CCC). Observations of the NH3(1,1) and (2,2) inversion transitions were obtained using the Nanshan 26 m radio telescope, while HCO+ (1-0), 12CO, 13CO, and C18O(1-0) transitions from the Purple Mountain Observatory Delingha 14 m telescope. Archival data are also included. We identified key observational signatures of CCC, including complementary spatial distributions, U-shaped structures, bridge features, and V-shaped velocity distributions. The position-velocity diagrams (P-V) reveal clear indications of gas interaction between two velocity components, suggesting an ongoing collision at an estimated angle of approximately 45 degree to the line of sight. The estimated collision timescale is 0.35-1.03 Myr, aligned with the inferred ages of young stellar objects (YSOs) in the region, supporting the hypothesis of collision-induced star formation. Hub-filament system (HFS) are identified in the compressed gas region, where filaments converge toward a dense hub, suggesting the CCC as a potential driver of HFS formation and massive star formation. The high column density suggests favorable conditions for the formation of massive stars. Although alternative kinematic drivers such as longitudinal collapse and shear motion are considered, CCC remains the most plausible explanation for the observed features. Our findings contribute to our understanding of the mechanisms of cloud dynamics and massive star formation in turbulent molecular environments.

Recently, Sawala et al. 2025 claimed to refute the cosmological significance of the Giant Arc based on their analysis of the FLAMINGO-10K simulation data. In our paper here, we highlight several shortcomings of the authors' analysis. We then perform an enhanced analysis on the FLAMINGO-10K simulation data with applications of: the Single-Linkage Hierarchical Clustering (SLHC), the Convex Hull of Member Spheres (CHMS), and the Minimal Spanning Tree (MST) algorithms. Using the full $2.8^3$ Gpc$^3$ FLAMINGO-10K box, with subhaloes at $z=0.7$, and $100$ random realisations (from random subset selections) we find no gigaparsec structures in FLAMINGO-10K, and only a few ultra-large large-scale structures (uLSSs, structures exceeding a maximum pairwise separation of $370$ Mpc). Somewhat surprisingly, we found that the large-scale aspects of the FLAMINGO-10K data could be adequately represented by a Poisson point distribution. The enhanced analysis presented here further supports the remarkable nature of the Giant Arc as a cosmologically-significant structure. Of course, the Giant Arc is also accompanied by a second uLSS, the Big Ring. The analysis presented here builds on the work presented by Sawala et al., but amends the application of their statistical assessments. We do not yet know why there appears to be such a large discrepancy between the FLAMINGO-10K data and the observed LSS in MgII absorbers. Perhaps the results presented here might suggest that the GA, and especially the GA + BR, presents a more direct challenge to $\Lambda$CDM. In contrast to the conclusion of Sawala et al. that 'gigaparsec patterns abound in a $\Lambda$CDM universe' we find that they are nowhere to be seen.

Despite its scientific importance, the low-surface-brightness universe has yet to be fully explored due to various systematic uncertainties that affect the achievable surface-brightness limit. Reducing these uncertainties requires very accurate data processing. The dark-sky flat is a widely used calibration frame for accurate flat-field correction, generated by combining the sky background from science images. However, the night sky will likely contain complex local fluctuations, thus may still lead to photometric errors in data calibrated with dark-sky flats. To address this concern, we conduct mock observations with semi-realistic sky simulation data and evaluate observation strategies to mitigate the impact of the fluctuating sky background. Our experiments consider two representative sky conditions (clear and dirty) and perform intensive comparative analysis on two observation methods (offset and rolling). Our findings suggest that the rolling dithering method, which incorporates the operation of camera rotation into conventional dithering, can provide more accurate dark-sky flats. Finally, we discuss the broader implications of this method through additional experiments examining several factors that may affect the imaging quality of observational data.

The thorough understanding on the initiation of coronal mass ejections (CMEs), which is manifested as a slow rise of pre-eruptive structures before the impulsive ejection in kinematics, is the key for forecasting the solar eruptions. In our previous work, we showed that the slow rise of a hot flux rope with coronal mass density is caused by the moderate magnetic reconnection occurring in the hyperbolic flux tube (HFT) combined with the torus instability. However, it remains unclear how the initiation process varies when a filament is present in the pre-eruptive flux rope. In this work, we reveal the complete initiation route of a CME containing filament mass with a state-of-the-art full-magnetohydrodynamics simulation. The comprehensive analyses show that the filament mass has an important impact on the CME initiation through triggering and driving the slow rise of flux rope with its drainage, besides the contributions of HFT reconnection and torus instability. Finally, in combination with our previous work, we propose that the enhanced drainage of filament mass and various features related to the HFT reconnection, such as, the split of pre-eruptive structure and the pre-flare loops and X-ray emissions, can serve as the precursors of CME initiation in observations.

We report the X-ray polarization properties of the high-synchrotron-peaked BL Lac H 1426+428, based on two-epoch observational data from the Imaging X-ray Polarimetry Explorer (IXPE). For the first observation, only an upper limit of polarization degree ($\Pi_{\rm X}$), $\Pi_{\rm X}<19.5\%$, at the 99\% confidence level (C.L.) is determined. In contrast, for the second observation, we derive $\Pi_{\rm X}=20.6\%\pm2.9\%$ with a polarization angle ($\psi_{\rm X}$) of $\psi_{\rm X}=116.1^{\circ}\pm4.1^{\circ}$ at a C.L. of 7.1 $\sigma$. The time-resolved and energy-resolved polarization analysis reveals no significant variation in $\psi_{\rm X}$ and no detectable polarization within narrower energy bins for the first observation, while the polarization during the second observation is predominantly dominated by low-energy photons. Furthermore, the X-rays during the second observation are found to be in a higher flux state with a harder spectrum compared to that observed during the first observation, consistent with a {\it harder-when-brighter} behavior. We propose that the plasma responsible for the X-ray emission during the first observation propagates downstream and encounters a shock, leading to electron acceleration and more ordered of the magnetic fields. The enhanced X-ray emission observed during the second observation is produced by shock-accelerated electrons within an ordered magnetic field region via synchrotron radiation. No significant detection of polarization during the first IXPE observation may be due to the limited number of detected photons.

Hypervelocity stars (HVSs) represent a unique class of objects capable of escaping the gravitational pull of the Milky Way due to extreme acceleration events, such as close encounters with the supermassive black hole at the Galactic center (GC), supernova explosions in binary systems, or multi-body dynamical interactions. Finding and studying HVSs are crucial to exploring these ejection mechanisms, characterizing central black holes, probing the GC environment, and revealing the distribution of dark matter in our galaxy. The Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) spectroscopic surveys have so far identified four B-type unbound HVSs. To expand this sample with the second-phase LAMOST survey that started in 2018, we conducted a systematic search for early-type HVSs using the LAMOST Data Release 10. We identified 125 early-type high-velocity candidates with total velocities exceeding 300 km\,s$^{-1}$. Among them, we report ten new unbound B- and A-type hypervelocity star (HVS) candidates (designated LAMOST-HVS5 through LAMOST-HVS14), tripling the number of unbound HVSs previously identified by LAMOST. Kinematic analyses suggest that these newly discovered HVS candidates likely originated either from the Galactic Center or via dynamical interactions. Future high-resolution follow-up observations promise to refine the stellar parameters, distances, and elemental abundances of these candidates, thereby providing deeper insights into their origins and broadening their potential applications across astrophysics.

Supersymmetry-based hybrid inflation models (referred to as 'spontaneously broken supersymmetry' by the Planck collaboration) are attractive for several reasons, including the appealing feature that inflation is associated with local gauge symmetry breaking in the early universe. Following the Planck collaboration's notation, the inflationary potential with sub-Planckian inflaton field values is given by: $V = \Lambda^4 [1 + \alpha_h \log(\phi / M_{Pl})] - m_{3/2} \Lambda^2 \phi + \Lambda^4 O((\phi / M_{Pl})^4)$. Here, $\Lambda = \sqrt{\kappa} M$ denotes the energy scale of inflation, $M$ is the gauge symmetry breaking scale, $\kappa$ is a dimensionless parameter that sets the inflaton mass ($\sqrt{2} \kappa M$), and $\alpha_h$ is determined from quantum corrections in terms of $\kappa$ and the underlying gauge group. A soft supersymmetry-breaking term proportional to the gravitino mass $m_{3/2}$ (~10 TeV) and linear in the inflaton field $\phi$ is also present during inflation. The final term in $V$ represents the leading-order supergravity correction. (Note that the last two terms were not taken into account in the Planck analysis.) We provide estimates for the parameters $\kappa$ (and $\alpha_h$) that yield a scalar spectral index $n_s$ in the range 0.96 to 0.98, which is fully consistent with recent P-ACT-LB measurements presented by the Atacama Cosmology Telescope, as well as earlier measurements by Planck. We recall that in the absence of the soft SUSY-breaking term proportional to $m_{3/2}$ in $V$, the spectral index $n_s = 1 - 1/N = 0.98$, where $N = 50$ denotes the number of e-foldings. The tensor-to-scalar ratio $r$ in this minimal model is tiny, but it can reach potentially observable values ($r \lesssim 0.01$) in non-minimal models.

Lyman-$\alpha$ damping wings towards quasars provide a unique probe of reionization because their strength correlates strongly with the global volume-averaged neutral hydrogen (HI) fraction of the intergalactic medium (IGM). Cosmic variance in the IGM, however, is a major source of stochasticity since the local neutral environment around a quasar varies significantly even at fixed global neutral fraction. We show that the IGM damping wing carries additional information about this local ionization topology, unexploited by current analysis frameworks. We introduce a set of two new physically motivated summary statistics encoding the local information about the HI distribution in the IGM before it is altered by ionization radiation from the quasar, encompassing 1) the HI column density, weighted by a Lorentzian profile mimicking the frequency dependence of the Lyman-$\alpha$ cross section, and 2) the distance from the quasar to the first neutral patch. This description, when combined with the quasar's lifetime as a third parameter, reduces the IGM transmission scatter in the damping wing region of the spectrum to $\lesssim 1\,\%$ across the full range of physical parameter space. We introduce a simple procedure for generating synthetic HI sightlines around quasars and demonstrate that the resulting damping wing profiles are statistically indistinguishable from a realistic reionization topology. This opens the door for optimally extracting the salient local information encoded in the imprint in a model-independent fashion. In the context of a specific reionization model, measurements of these local parameters can be translated into constraints on the global timing of reionization, but in addition, they provide information about the reionization topology, hitherto unused. A marginally modified version of our framework can also be employed in the context of damping wings towards galaxies.

Once per 10,000-100,000 years, an unlucky star may experience a close encounter with a supermassive black hole (SMBH), partially or fully tearing apart the star in an exceedingly brief, bright interaction called a tidal disruption event (TDE). Remnants of partial TDEs are expected to be plentiful in our Galactic Center, where at least six unexplained, diffuse, star-like "G objects" have already been detected which may have formed via interactions between stars and the SMBH. Using numerical simulations, this work aims to identify the characteristics of TDE remnants. We take 3D hydrodynamic FLASH models of partially disrupted stars and map them into the 1D stellar evolution code MESA to examine the properties of these remnants from tens to billions of years after the TDE. The remnants initially exhibit a brief, highly luminous phase, followed by an extended cooling period as they return to stable hydrogen burning. During the initial stage (< 10,000 yr) their luminosities increase by orders of magnitude, making them intriguing candidates to explain a fraction of the mysterious G objects. Notably, mild TDEs are the most common and result in the brightest remnants during this initial phase. However, most remnants exist in a long-lived stage where they are only modestly offset in temperature and luminosity compared to main-sequence stars of equivalent mass. Nonetheless, our results indicate remnants will sustain abnormal, metal-enriched envelopes that may be discernible through spectroscopic analysis. Identifying TDE survivors within the Milky Way could further illuminate some of the most gravitationally intense encounters in the Universe.

We have discovered a substantial sodium doublet (Na D $\lambda\lambda$5890, 5896\AA)-traced neutral outflow in a quenching galaxy JADES-GS-206183 at $z=1.317$ in GOODS-S field. Its JWST NIRSpec/MSA spectrum shows a significantly blueshifted and deep Na D absorption, revealing a neutral outflow with a velocity of $v_{\rm out}=828^{+79}_{-49}\,\mathrm{km\,s^{-1}}$ and a mass outflow rate of $\log(\dot{M}_{\rm out}/\mathrm{M_{\odot}\,yr^{-1}})=2.40^{+0.11}_{-0.16}$. The mass outflow rate of this outflow is higher than any of the neutral outflows identified previously beyond $z\sim1$ by the same line diagnostic and is comparable with those in local galaxies with extremely strong star formation activities or luminous AGN. Nonetheless, the best-fit SED modeling of JADES-GS-206183, based on its multi-band photometry from HST/ACS to JWST/NIRCam, suggests that the host galaxy now is quenched, and the Paschen $\alpha$ (Pa$\alpha$) emission in the FRESCO NIRCam grism spectrum confirms its current low star formation rate ($10.78\pm 0.55\,\mathrm{M_{\odot}\,yr^{-1}}$). More surprisingly, optical line ratio diagnostics indicate that the current AGN activity of JADES-GS-206183, if present, is weak. Even though we tentatively detect a broad component of the H$\alpha$ line, it is more likely tracing the ionized outflow than an AGN. The results demonstrate that the Na D outflow in JADES-GS-206183 is highly unlikely to be driven by current star formation or nuclear activity. Instead, we propose that the outflow that we are witnessing in JADES-GS-206183 may be a long-lasting fossil outflow, powered by previous AGN activity that has recently shut down.

We performed star counts in the region of the open cluster NGC 3532. The ranges of trigonometric parallaxes and proper motions containing all the stars of the cluster were determined using the stars with 5- and 6-parameter Gaia DR3 solutions. The estimated radius of the cluster was R_c=178+-3 arcminutes and the number of cluster stars was N_c=2200+-40. We estimate the number of stars with poor astrometric solutions that may be members of the cluster. For this purpose, we analyze the surface density distribution of stars with two-parameter Gaia DR3 solutions, stars with the parameter RUWE>1.4, and stars with large relative errors of trigonometric parallaxes in the vicinity of the cluster. We are looking for stars that fall within the area of the color-magnitude diagram occupied by probable members of the NGC 3532 cluster from the Hant&Reffert sample. The radial surface density profile plotted with such stars shows the concentration of stars toward the cluster center. An analysis of the profile yields an estimate of 2150+-230 stars that may be cluster members. Thus, nearly one half of cluster members can be lost when the probable members are selected only by exact astrometric data of Gaia DR3. Among these lost stars, there may be a significant number of unresolved binary and multiple systems.

The 21cm forest, narrow absorption features in the spectra of high redshift radio sources caused by intervening neutral hydrogen, offers a unique probe of the intergalactic medium and small-scale structures during reionization. While traditional power spectrum methods have been widely used for analyzing the 21cm forest, these techniques are limited in capturing the non-Gaussian nature of the signal. In this work, we introduce the Wavelet Scattering Transform (WST) as a novel diagnostic tool for the 21cm forest, which allows for the extraction of higher-order statistical features that power spectrum methods cannot easily capture. By decomposing simulated brightness temperature spectra into a hierarchy of scattering coefficients, the WST isolates both local intensity fluctuations (first-order coefficients) and scale-scale correlations (second-order coefficients), revealing the complex, multi-scale non-Gaussian interactions inherent in the 21cm forest. This approach enhances the power of 21cm forest in distinguishing between different cosmological models, such as Cold Dark Matter (CDM) and Warm Dark Matter (WDM), as well as scenarios with enhanced X-ray heating. Unlike traditional methods, which focus primarily on Gaussian statistics, the WST captures richer astrophysical and cosmological information. Our analysis shows that WST can significantly improve constraints on key parameters, such as the X-ray heating efficiency and the WDM particle mass, providing deeper insights into the early stages of cosmic structure formation.

Cosmic voids are underdense regions within the large-scale structure of the Universe, spanning a wide range of physical scales - from a few megaparsecs (Mpc) to the largest observable structures. Their distinctive properties make them valuable cosmological probes and unique laboratories for galaxy formation studies. A key aspect to investigate in this context is the galaxy bias, $b$, within voids - that is, how galaxies in these underdense regions trace the underlying dark-matter density field. We want to measure the dependence of the large-scale galaxy bias on the distance to the void center, and to evaluate whether this bias profile varies with the void properties and identification procedure. We apply a void identification scheme based on spherical overdensities to galaxy data from the IllustrisTNG magnetohydrodynamical simulation. For the clustering measurement, we use an object-by-object estimate of large-scale galaxy bias, which offers significant advantages over the standard method based on ratios of correlation functions or power spectra. We find that the average large-scale bias of galaxies inside voids tends to increase with void-centric distance when normalized by the void radius. For the entire galaxy population within voids, the average bias rises with the density of the surrounding environment and, consequently, decreases with increasing void size. Due to this environmental dependence, the average galaxy bias inside S-type voids - embedded in large-scale overdense regions - is significantly higher ($\langle b\rangle_{\rm in} > 0$) at all distances compared to R-type voids, which are surrounded by underdense regions ($\langle b\rangle_{\rm in} < 0$). The bias profile for S-type voids is also slightly steeper. Since both types of voids host halo populations of similar mass, the measured difference in bias can be interpreted as a secondary bias effect.

Semidetached binaries, distinguished by their mass transfer phase, play a crucial role in elucidating the physics of mass transfer within interacting binary systems. To identify these systems in eclipsing binary light curves provided by large-scale time-domain surveys, we have developed a methodology by training two distinct models that establish a mapping relationship between the parameters (orbital parameters and physical parameters) of semidetached binaries and their corresponding light curves. The first model corresponds to scenarios where the more massive star fills its Roche lobe, while the second model addresses situations where the less massive star does so. In consideration of the O'Connell effect observed in the light curves, we integrated a cool spot parameter into our models, thereby enhancing their applicability to fit light curves that exhibit this phenomenon. Our two-model framework was then harmonized with the Markov Chain Monte Carlo algorithm, enabling precise and efficient light-curve fitting and parameter estimation. Leveraging 2 minute cadence data from the initial 67 sectors of the Transiting Exoplanet Survey Satellite, we successfully identified 327 systems where the less massive component fills its Roche lobe, alongside three systems where the more massive component fills its Roche lobe. Additionally, we offer comprehensive fundamental parameters for these binary systems, including orbital inclination, relative radius, mass ratio, and effective temperature.

The $S_8$ parameter, which quantifies the amplitude of matter fluctuations on scales of $8h^{-1}$ Mpc, has been a source of tension between weak lensing surveys (e.g. KiDS, DES, HSC) and the Planck Cosmic Microwave Background (CMB) measurements. This discrepancy challenges the standard ${\Lambda}$CDM model and has become one of the most significant tensions in modern cosmology. The ${\Lambda'}$ model offers a potential resolution by introducing modifications to the cosmic growth history through alterations to the gravitational sector. The alterations involve including a Ricci soliton into Einstein's field equations which introduce a time dependent factor yielding a time varying cosmological constant ${\Lambda'}=(1-{\alpha(t)^2}(t)){\Lambda_{DE}}\frac{{\rho}_g}{\rho_{DE}}$ and subsequently the evolution of the cosmos. The Ricci soliton is sourced from gravitational energy density. In this study we analyze results from six surveys and compare the results for $w_a$ and $w_0$ with the ${\Lambda'}$ model. We also find ${\sigma}_8={0.750}_{-0.020}^{+0.020}$ , $S_8={0.788}$. These values are closer to some low $S_8$ measurements from weak lensing surveys (e.g DES, KiDS), which report $S_8 \approx 0.76-0.78$, suggesting that the model may alleviate the $S_8$ tension. High values of ${\alpha(t)}$ in the late universe are the cause of suppressed structure formation and low values of ${\Lambda'}$. The late universe in the ${\Lambda'}$ model is effectively or apparently 5-10% younger than in ${\Lambda}$CDM which translates to $H_0={72.734}_{-1.687}^{+1.687}$ km/s/Mpc, which is in agreement with late universe probes. ${\Lambda'}$ is classified under the dynamical dark energy models, however unlike alternatives, it does not invoke exotic particles nor phantom energy.

We present late-time optical and infrared (IR) observations of a sample of nine extragalactic Luminous Red Novae (LRNe) discovered in the last three decades. In all these cases, the LRN survivors fade below the pre-outburst luminosity of the progenitors in the optical region. Instead, they remain visible in the near-IR (NIR), and bright in the mid-IR (MIR) domains for years. We recover AT 1997bs in $Spitzer$ images from 2004, and a residual source is visible in HST and $JWST$ NIR images 27 years after the outburst. Its spectral energy distribution (SED) is consistent with that of a red supergiant star with a photospheric temperature of 3200 K and a radius of 220 $R_{\odot}$, without a significant circumstellar dust attenuation, as the source is not detected at 4.5 $\mu$m. Another LRN, AT 2011kp, is detected by $JWST$ 12.5 years after the outburst. From its SED, we find evidence for three black-body components: a warm/hot stellar component, a colder component from cool dust at 425 K, emitting between 3 and 6 $\mu$m, and a third even colder component responsible for the excess at 8 $\mu$m, possibly due to an IR echo. We construct the $[3.6]-[4.5]$ colour curves extending up to +7 years for six LRNe, which show a similar evolution: the MIR colour is $\sim0$ before the optical maximum light, it becomes bluer ($\sim-0.5$ mag) at around +1 year, then it gradually turns to redder colours ($\sim+0.5$ mag) in the following years, before reaching $[3.6]-[4.5]\sim+1.5$ mag 7 years after the outburst. Finally, we also estimate the masses and the temperatures of newly-formed dust years after the LRN onset for different chemical compositions (silicates or graphite) and grain sizes (0.1 or 1.0 $\mu$m). We find that LRNe produce dust masses of the order of (0.1-30)$\times10^{-6}$ $M_{\odot}$ between 3.6 and 13 years after the outbursts, with temperatures in the range from 350 to 770 K.

Searching for primordial gravitational wave in cosmic microwave background (CMB) polarization signal is one of the key topics in modern cosmology. Cutting-edge CMB telescopes requires thousands of pixels to maximize mapping speed. Using modular design, the telescope focal plane is simplified as several detector modules. Each module has hundreds of pixels including antenna arrays, detector arrays, and readout arrays. The antenna arrays, as the beam defining component, determine the overall optical response of the detector module. In this article, we present the developments of 6-inch broadband antenna arrays from 80GHz to 170GHz for the future IHEP focal plane module. The arrays are fabricated from 42 6-inch silicon wafers including 456 antennas, 7% more pixels than usual design. The overall in-band cross polarization is smaller than -20 dB and the in-band beam asymmetry is smaller than 10%, fulfilling the requirements for primordial gravitational wave search.

The red supergiant (RSG) problem refers to the observed dearth of luminous RSGs identified as progenitors of Type II supernovae (SNe II) in pre-SN imaging. Understanding this phenomenon is essential for studying pre-SN mass loss and the explodability of core-collapse SNe. In this work, we re-assess the RSG problem using late-phase spectroscopy of a sample of 50 SNe II. The [O I] $\lambda\lambda$6300,6363 emission in the spectra is employed to infer the zero-age main sequence (ZAMS) mass distribution of the progenitors, which is then transformed into a luminosity distribution via an observation-calibrated mass-luminosity relation. The resulting luminosity distribution reveals an upper cutoff at log $L/L_{\odot} = 5.21^{+0.09}_{-0.07}$ dex, and the RSG problem is statistically significant at the 2$\sigma$ to 3$\sigma$ level. Assuming single RSG progenitors that follow the mass-luminosity relation of KEPLER models, this luminosity cutoff corresponds to an upper ZAMS mass limit of $20.63^{+2.42}_{-1.64}$ $M_{\odot}$. Comparisons with independent measurements, including pre-SN imaging and plateau-phase light curve modeling, consistently yield an upper ZAMS mass limit below about 25 $M_{\odot}$, with a significance level of 1-3$\sigma$. While each individual method provides only marginal significance, the consistency across multiple methodologies suggests that the lack of luminous RSG progenitors may reflect a genuine physical problem. Finally, we discuss several scenarios to account for this issue should it be confirmed as a true manifestation of stellar physics.

In this study, we further developed and investigated the dual parameter phenomenological dark energy model (H^2 + H^-2 dark energy model) derived from Kaniadakis holographic dark energy. On the theoretical basis of the original H^2 + H^-2 dark energy model (HHDE), four types of viscosities and seven types of interactions were introduced. These were combined pairwise, and a dynamical analysis was conducted on a total of 35 Modified H^2 + H^-2 Viscous Interacting Dark Energy (MHH-VIDE) models. The advantage of the HHDE model and MHH-VIDE models is that these models can greatly relieve the Hubble tension and cicumventing the potential issue of a 'big rip', and the dark energy is Quintom-like. In this article, we performed a three-dimensional dynamical analysis of the aforementioned models with interactions and viscosity, testing their viability. The results suggest that the nature of this dark energy is closer to a property of spacetime than a cosmological component. The phase diagram analysis reveals a modified radiation-dominated epoch, a transitional matter-dominated phase, and a late-time attractor corresponding to the dark-energy-driven acceleration phase.

Measurement of environmental parameters is one of the basic requirements for the proper operation of a telescope. This memo is intended to provide guidance for the measurement accuracy requirements in the context of the ngVLA. It relies on previous work for ALMA (Mangum, 2001) and EVLA (Butler \& Perley, 2008) and a review of the subject by Mangum \& Wallace (2015). The local operational environment can be broadly divided into two categories: electromagnetic and physical. Meteorological parameters (weather) primarily constitute the physical environmental component and radio frequency interference (RFI) is the essential element of the electromagnetic environment. This memo focuses on the weather component and does not address the RFI, safety and physical infrastructure components. Under weather, the relevant topics are (1) the correction to pointing arising from refraction in the atmosphere (2) the different delays in the arrival times of signals at different antennas due to propagation in the atmosphere (3) monitoring weather parameters to provide operations support, e.g. in determining prevalence of precision or normal conditions, dynamic scheduling and the choice of antennas to constitute a sub-array with a given set of characteristics, among others, and (4) archival. Here we restrict ourselves to the first two topics which impact the data obtained and its calibration.

The ngVLA is a new interferometric radio astronomy facility with transformative capabilities, being developed by the National Radio Astronomy Observatory. It combines two orders of magnitude in frequency coverage, over 1.2 - 116 GHz, with unprecedented sensitivity, spatial resolution and spatial frequency coverage, opening up new discovery space, impacting nearly every area of astrophysics. The high sensitivity that enables the path breaking science goals, which in turn lead to stringent instrument requirements, also open up new approaches to meeting them, previously only possible in limited contexts. Chief among the requirements are the image dynamic range specifications of 45 dB and 35 dB at 8 GHz and 27 GHz in single pointing and mosaiced observations. As the baseline calibration strategy to meet these requirements, we leverage the high ngVLA sensitivity through routine use of self-calibration on short time scales to counter atmospheric delay fluctuations and pointing self-calibration to correct for pointing errors. A key benefit of leveraging self-calibration techniques, where possible, is the a reduction in system complexity of a range of subsystems, which in turn improves system reliability. Self-calibration also promises the possibility of attaining thermal noise limited dynamic range performance in some cases. This presentation provides the bases for these approaches, illustrating them to make the case for their application to the ngVLA in parallel.

The ngVLA is a new interferometric radio astronomy facility with transformative capabilities, being developed by the National Radio Astronomy Observatory. It combines two orders of magnitude in frequency coverage, over 1.2 - 116 GHz, with unprecedented sensitivity, spatial resolution and spatial frequency coverage, opening up new discovery space, impacting nearly every area of astrophysics. The high sensitivity that enables the path breaking science goals, which in turn lead to stringent instrument requirements, also open up new approaches to meeting them, previously only possible in limited contexts. Chief among the requirements are the image dynamic range specifications of 45 dB and 35 dB at 8 GHz and 27 GHz in single pointing and mosaiced observations. As the baseline calibration strategy to meet these requirements, we leverage the high ngVLA sensitivity through routine use of self-calibration on short time scales to counter atmospheric delay fluctuations. We recognize the broader nature of the problem - requiring a certain dynamic range, DR, at a targeted science noise level {\sigma}_science presupposes the presence of bright emission in the field at a corresponding level of detected interferometric flux of \sim DR \times {\sigma}_science, by definition. With the problem posed broadly in this way, one can derive a general limit without recourse to background source counts and the attendant Poisson fluctuations of their occurrence, and which depends only on the number of antennas in the array and the science noise level of the observation, independent of the observing band, primary beam size and antenna SEFDs. This memo formally explores these ideas as the main strategy to achieve the ngVLA image dynamic range requirements.

Upcoming wide-field time-domain surveys, such as the Vera C. Rubin Observatory's Legacy Survey of Space and Time (LSST) are expected to discover up to two orders of magnitude more strongly lensed supernovae per year than have so far been observed. Of these, Type IIn supernovae have been predicted to be detected more frequently than any other supernova type, despite their small relative detection fraction amongst non-lensed supernovae. However, previous studies that predict a large population of lensed Type IIn supernova detections model their time evolving spectrum as a pure blackbody. In reality, there is a deficit in the UV flux of supernovae relative to the blackbody continuum due to line-blanketing from iron-group elements in the ejecta and scattering effects. In this work we quantify the effect of this UV suppression on the detection rates by LSST of a simulated population of strongly lensed Type IIn supernovae, relative to a pure blackbody model, using a mock LSST observing run. With a blackbody model, we predict to detect $\sim$70 lensed Type IIn supernova per year with LSST. By modelling a similar UV deficit to that seen in superluminous supernovae, we recover 60 - 80% of the detections obtained using a pure blackbody model, of which $\sim$10 detections per year are sufficiently bright ($m_\textrm{i} < 22.5$ mag) and detected early enough (> 5 observations before lightcurve peak) to enable high-cadence spectroscopic follow up.

Context:Halo formation time, which quantifies the mass assembly history of dark-matter halos, directly impacts galaxy properties and evolution. Although not directly observable, it can be inferred through proxies like star formation history or galaxy spatial distributions. Recent advances in machine learning enable more accurate predictions of halo formation time using galaxy and halo properties. Aims:This study aims to investigate a machine learning-based approach to predict halo formation time-defined as the epoch when a halo accretes half of its current mass-using both halo and baryonic properties derived from cosmological simulations. By incorporating properties associated with the brightest cluster galaxy located at the cluster center, its associated intracluster light component and satellite galaxies, we aim to surpass these analytical predictions, improve prediction accuracy and identify key properties that can provide the best proxy for the halo assembly history. Methods:Using The Three Hundred cosmological simulations, we train Random Forest (RF) and Convolutional Neural Network (CNN) models on halo and baryonic properties, such as mass, concentration, stellar and gas masses, and features of the brightest cluster galaxy and intracluster light. CNN models are trained on two-dimensional radial property maps. We also construct simple linear models using only observationally accessible features. Results:RF models show median biases of 4%-9% with standard deviations of 20%. CNN models reduce median bias to <4%, although they have higher scatter. Simple linear models using a limited number of observables achieve prediction accuracy comparable to RF models. Traditional relations between halo formation time and mass/concentration are preserved.

We investigate potential deviations from cold dark matter (CDM) using the latest Baryon Acoustic Oscillations (BAO) measurements from the Dark Energy Spectroscopic Instrument (DESI). Analyzing DESI data alone constrains the dark matter equation of state parameter $w_{\mathrm{dm}} = -0.042^{+0.047}_{-0.024}$, revealing a mild preference for non-cold dark matter. This preference strengthens significantly in combined analyses, but reveals a striking tension in the inferred $w_{\mathrm{dm}}$ values from observations of different nature. The DESI+DESY5 combination yields $w_{\mathrm{dm}} = -0.084 \pm 0.035$, excluding CDM ($w_{\mathrm{dm}}=0$) at 2.4$\sigma$ significance. In contrast, Planck+DESI gives $w_{\mathrm{dm}} = 0.00077\pm0.00038$, differing from concordance model at 2$\sigma$ significance. The non-vanishing $w_{\mathrm{dm}}$ preference is particularly driven by low-redshift BAO measurements ($z<1.1$), while higher redshift data remain consistent with $\Lambda$CDM. The evidence for non-cold dark matter is more pronounced in DESI compared to the previous BAO surveys. All dataset combinations show significant improvement over the $\Lambda$CDM paradigm, providing compelling evidence for non-cold dark matter scenario.

Multi-line spectropolarimetric observations allow for the simultaneous inference of the magnetic field at different layers of the solar atmosphere and provide insight into how these layers are magnetically coupled. The new upgrade of the Gregor Infrared Spectrograph (GRIS) instrument offers such a possibility, allowing for the simultaneous observation of the Ca II line at 8542 A, the Si I line at 10827 A, and the He I triplet at 10830 A in addition to some additional weaker spectral lines that can probe deeper in the photosphere. Because these spectral lines are sensitive to the plasma properties at different regions of the solar atmosphere, their combined analysis can help understand the stratification of its thermal and magnetic properties from the photosphere to the chromosphere. This work showcases recent observations of the upgraded GRIS at the active region AR13724, which shows the instrument's potential for unravelling the most minute details of solar phenomena. In particular, we analyse the spatial distribution of the polarisation signals as well as the distribution of Stokes profiles for different regimes of the magnetic field strength. We also conduct a preliminary data analysis using relatively simple and approximate methods.

Dusty stellar point sources are a significant stage in stellar evolution and contribute to the metal enrichment of galaxies. These objects can be classified using photometric and spectroscopic observations with color-magnitude diagrams (CMD) and infrared excesses in spectral energy distributions (SED). We employed supervised machine learning spectral classification to categorize dusty stellar sources, including young stellar objects (YSOs) and evolved stars (oxygen- and carbon-rich asymptotic giant branch stars, AGBs), red supergiants (RSGs), and post-AGB (PAGB) stars in the Large and Small Magellanic Clouds, based on spectroscopic labeled data from the Surveying the Agents of Galaxy Evolution (SAGE) project, which used 12 multiwavelength filters and 618 stellar objects. Despite missing values and uncertainties in the SAGE spectral datasets, we achieved accurate classifications. To address small and imbalanced spectral catalogs, we used the Synthetic Minority Oversampling Technique (SMOTE) to generate synthetic data points. Among models applied before and after data augmentation, the Probabilistic Random Forest (PRF), a tuned Random Forest (RF), achieved the highest total accuracy, reaching $\mathbf{89\%}$ based on recall in categorizing dusty stellar sources. Using SMOTE does not improve the best model's accuracy for the CAGB, PAGB, and RSG classes; it remains $\mathbf{100\%}$, $\mathbf{100\%}$, and $\mathbf{88\%}$, respectively, but shows variations for OAGB and YSO classes. We also collected photometric labeled data similar to the training dataset, classifying them using the top four PRF models with over $\mathbf{87\%}$ accuracy. Multiwavelength data from several studies were classified using a consensus model integrating four top models to present common labels as final predictions.

Understanding the origin of substructures in protoplanetary disks and their connection to planet formation is currently one of the main challenges in astrophysics. While some disks appear smooth, most exhibit diverse substructures such as gaps, rings, or inner cavities, with varying brightness and depth. As part of the Ophiuchus Disk Survey Employing ALMA (ODISEA), we previously proposed an evolutionary sequence to unify this diversity, driven by the formation of giant planets through core accretion and subsequent planet-disk interactions. By combining the disk evolution and planet formation code PLANETALP with the radiative transfer code RADMC-3D, we have now reproduced the key aspects of the proposed evolutionary sequence. Starting with a smooth disk (like e.g., WLY 2-63), we modeled the evolution of a fiducial disk with a 1 Jupiter-mass planet at 57 au. Within a few hundreds of orbits, a narrow gap forms, resembling ISO-Oph 17. By $\sim$0.1 Myr, the gap widens, and dust accumulates at the cavity edge, producing a structure similar to Elias 2-24. At $\sim$0.4 Myr, the disk evolves further into a morphology akin to DoAr 44, characterized by a smaller inner disk and a brighter inner rim. By $\sim$1 Myr, the system transitions to a single narrow ring, resembling RXJ1633.9-2442. This line of work strongly supports the planetary origin of substructures and enables the possibility of identifying a population of planets that is currently beyond the reach of more direct detection techniques.

The young (23 Myr) nearby (19.4 pc) star $\beta$ Pictoris hosts an edge-on debris disk with two gas giant exoplanets in orbit around it. Many transient absorption features have been detected in the rotationally broadened stellar lines, which are thought to be the coma of infalling exocomets crossing the line of sight towards Earth. In the Solar System, the molecule cynaogen (CN) and its associated ionic species are one of the most detectable molecules in the coma and tails of comets. We perform a search for cyanogen in the spectra of $\beta$ Pictoris to detect or put an upper limit on this molecule's presence in a young, highly active planetary system. We divide twenty year's worth of HARPS spectra into those with strong exocomet absorption features, and those with only stellar lines. The high signal-to-noise stellar spectrum normalises out the stellar lines in the exocomet spectra, which are then shifted and stacked on the deepest exocomet absorption features to produce a high signal-to-noise exocomet spectrum, and search for the CN band head using a model temperature dependent cross-correlation template. We do not detect CN in our data, and place a temperature and broadening dependent 5$\sigma$ upper limit between 10$^{12}$ cm$^{-2}$ and 10$^{13}$ cm$^{-2}$, to be compared to the typical 10$^9$ - 10$^{10}$ cm$^{-2}$ expected from scaling of the values in the Solar System comets.

Lorentz invariance violation in photons can be quantified by measuring the difference in arrival times between high- and low-energy photons originating from gamma-ray bursts (GRBs). When analyzing data, it is crucial to consider the inherent time delay in the emission of these photons at the source of the GRB. In a recent study, three distinct models were evaluated to explain the intrinsic emission times of high-energy photons by analyzing 14 multi-GeV photon events detected from 8 GRBs using the Fermi Gamma-ray Space Telescope (FGST). In this study, we examine three remarkable GRB photons recorded by different observatories: the 99.3~GeV photon from GRB 221009A observed by FGST, the 1.07~TeV photon from GRB 190114C detected by the Major Atmospheric Gamma Imaging Cherenkov (MAGIC) telescope, and the 12.2~TeV photon from GRB 221009A observed by the Large High Altitude Air-shower Observatory (LHAASO). Our analysis indicates that the newly proposed model with a linear relationship between photon energy and intrinsic emission time can offer a consistent framework to explain the behavior of all three exceptional photons with a Lorentz violation scale $E_{\rm LV}\sim 3\times 10^{17}$~GeV.

Circumstellar interaction of supernova (SN) ejecta is an essential process in its evolution and observations of SNe have found the signature of circumstellar interaction both in the early and late evolutionary phase of SNe. In this Letter, we show that if the SN forward shock plunges into tenuous stellar wind from dense circumstellar medium (CSM) in the vicinity of the progenitor (i.e., confined CSM), the subsequent time evolutions of the SN-CSM interaction system deviates from the prediction of self-similar solution. In this case, after all of the confined CSM is swept up by the SN forward shock (roughly $10$ days after the explosion), the propagation of the shocked shell will be driven by the freely expanding ram pressure of the confined CSM component, instead of the SN ejecta. Meanwhile, the forward shock decelerates faster than the prediction of thin-shell approximation once the confined CSM component reaches homologous expansion. This lasts until the reverse shock in the confined CSM component reaches the head of the SN ejecta, leading to the restoration of the system into the evolutionary model without confined CSM, where the SN ejecta drives the expansion of the system. We also show that this peculiar evolution will be reflected in observational signatures originating from SN-CSM interaction, taking rapid decline and rebrightening of radio emission as examples. Our results shed light on the importance of taking into account the effect of initial SN-CSM interaction even when we focus on observational properties of SNe a few years after the explosion.

The Magellanic Clouds (MCs) are excellent locations to study stellar dust emission and its contribution to galaxy evolution. Through spectral and photometric classification, MCs can serve as a unique environment for studying stellar evolution and galaxies enriched by dusty stellar point sources. We applied machine learning classifiers to spectroscopically labeled data from the Surveying the Agents of Galaxy Evolution (SAGE) project, which involved 12 multiwavelength filters and 618 stellar objects at the MCs. We classified stars into five categories: young stellar objects (YSOs), carbon-rich asymptotic giant branch (CAGB) stars, oxygen-rich AGB (OAGB) stars, red supergiants (RSG), and post-AGB (PAGB) stars. Following this, we augmented the distribution of imbalanced classes using the Synthetic Minority Oversampling Technique (SMOTE). Therefore, the Probabilistic Random Forest (PRF) classifier achieved the highest overall accuracy, reaching ${89\%}$ based on the recall metric, in categorizing dusty stellar sources before and after data augmentation. In this study, SMOTE did not impact the classification accuracy for the CAGB, PAGB, and RSG categories but led to changes in the performance of the OAGB and YSO classes.

The phosphorus budget of planets is intertwined with their formation history and is thought to influence their habitability. The chemical reservoirs and volatile \emph{vs} refractory budget of phosphorus in planet-forming environments have so far eluded empirical characterisation. We employ high-resolution spectra from HST/STIS in the ultraviolet and APEX in the sub-mm to constrain the phosphorus budget in the well-characterized HD\,100546 star and protoplanetary disk system. We measure $\log{(P/H)_{\star}}=-7.50^{+0.23}_{-0.28}$ on the stellar surface, which traces the total inventory of P in accreting gas \emph{and }dust from the inner disk. The inner disk gas, inside of the main dust trap, has $\log{(P/H)_{\rm in}}\lesssim-8.70$, and the outer disk gas $\log{(P/H)_{\rm out}}\lesssim-9.30$. Phosphorus in the disk is carried by a relatively refractory reservoir, consistent with minerals such as apatite or schreibersite, or with ammonium phosphate salts, in terms of sublimation temperature. We discuss the impact this might have on the two protoplanets around HD\,100546. Our results contribute to our understanding of the chemical habitability of planetary systems and lay a foundation for future explorations, especially in the context of JWST and \emph{Ariel} which can study phosphorus in exoplanet atmospheres.

We present a comprehensive analysis of the 'canonical' soft state ($\gamma$, $\delta$, and $\phi$ spectral variability classes) of the black hole binary GRS 1915+105, using RXTE, AstroSat, and NuSTAR data from 1996 to 2017 to investigate the origin of High Frequency Quasi-periodic Oscillations (HFQPOs). Our findings reveal that HFQPOs occur only in the $\gamma$ and $\delta$ classes, with frequencies of $65.07-71.38$ Hz and are absent in the $\phi$ class. We observe an evolution of time-lag from hard-lag (1.59$-$7.55 ms) in RXTE to a soft-lag (0.49$-$1.68 ms) in AstroSat observations. Wide-band (0.7$-$50 keV) spectral modelling suggests that HFQPOs are likely observed with a higher covering fraction ($f_{cov} \gtrsim 0.5$), i.e., the fraction of seed photons being Comptonized in the corona, enhanced Comptonized flux ($\sim$ 38%), and lower optical depth ($\tau \lesssim 8.5$ ) in contrast to observations where HFQPOs are absent. We observed similar constraints for observing HFQPOs during an inter-class ($\phi \rightarrow \delta$) transition as well as in a few intra-class ($\delta \rightarrow \delta$) variations. We also find that the time-lag decreases as $\tau$ increases, indicating that a higher $\tau$ reduces Compton up-scattering, thereby decreasing the hard-lag. Interestingly, in RXTE observations, the hard-lag ($\sim$ 7 ms) gradually decreases as optical depth and Comptonization ratio increases, eventually becoming a soft-lag ($\sim$1 ms) in AstroSat observations. These constraints on spectro-temporal parameters for the likelihood of observing HFQPOs support a 'compact' coronal oscillation mechanism for generating HFQPOs, which we attempt to explain within the framework of a possible accretion scenario.

We theoretically analyze the dipole anisotropy observed in the quasar distribution from the CatWISE2020 catalog. The catalog data shows a peak around $z\approx 1$, suggesting the presence of a large-scale dipole component. We explore the possibility that this dipole could be driven by primordial density fluctuations from modes that were superhorizon at the time of CMB decoupling but have since entered the horizon and become subhorizon. In particular, we consider the impact of adiabatic modes with wavenumbers $k$ in the range $(10^{-4} - 4 \times 10^{-3})~\mathrm{Mpc}^{-1} $, corresponding to wavelength scales of several Gpc. Such modes can create large-scale density variations, likely causing anisotropies in the distribution of matter and, as a result, affecting the number density of observed quasars. We also demonstrate that a superhorizon curvature perturbations mode, with comoving wavenumber $k\lesssim0.3H_0$ can lead to a significant enhancement in the locally inferred Hubble constant. This effect offers a viable explanation for the observed discrepancy between local and CMB inferred measurements of $H_0$.

In this study, we conducted a comprehensive analysis of the SX Phoenicis (SX Phe) type star CY Aquarii (CY Aqr). Our investigation included a detailed $O-C$ analysis based on a 90-year observational dataset, augmented by 1,367 newly determined times of maximum light. The $O-C$ diagram reveals that (i) the primary star of CY Aqr exhibits a linear period variation rate of $(1/P_0)(\mathrm{d} P/ \mathrm{d} t) = (2.132 \pm 0.002) \times 10^{-8} \mathrm{yr}^{-1}$ for its dominant pulsation mode; (ii) the primary star is disturbed by two companions and part of a triple system; (iii) Companion A has an orbital period of approximately 60.2 years and Companion B has an orbital period of approximately 50.8 years. It is highly probable that both Companion A and B are white dwarfs, with Companion A's elliptical orbit displaying an eccentricity of $e = 0.139 \pm 0.002$, which is the lowest confirmed value in similar binary and triple systems to date. Most notably, Companion A and B have masses that are identical within the uncertainties, with a mass ratio exceeding 0.99. Whether this is considered a coincidental event or the result of an underlying mechanism, CY Aqr is an exceptionally rare case that broadens our understanding of multiple star systems and offers a unique opportunity to delve into the enigmatic evolutionary histories of such configurations. Further intriguing characteristics of this system warrant investigation in future studies, based on additional observational data.

In this work, we present a study on the long time-scale period variations of four single-mode high-amplitude delta Scuti stars (HADS) via the classical $O-C$ analysis. The target HADS are (i) XX Cygni, (ii) YZ Bootis, (iii) GP Andromedae, and (iv) ZZ Microscopii. The newly determined times of maximum light came from the Transiting Exoplanet Survey Satellite (TESS), American Association of Variable Star Observers (AAVSO), and Bundesdeutsche Arbeitsgemeinschaft f$\ddot{\rm u}$r Ver$\ddot{\rm a}$nderliche Sterne (BAV) projects. Together with the times of maximum light obtained in the historical literature, the $O-C$ analysis was performed on these HADS, in which we obtained the linear period variation rates $\dot{P}/P$ as $(9.2 \pm 0.2) \times 10^{-9} \ \mathrm{yr^{-1}}$, $(3.2\pm 0.2)\times 10^{-9} \ \mathrm{yr^{-1}}$, $(4.22\pm 0.03) \times 10^{-8} \ \mathrm{yr^{-1}}$, and $(-2.06 \pm 0.02) \times 10^{-8} \ \mathrm{yr^{-1}}$, respectively. Based on these results and some earlier research, we also discuss the evolutionary stages and the mechanisms of the period variation of these four HADS.

In astrophysical simulations, nuclear reacting flows pose computational challenges due to the stiffness of reaction networks. We introduce neural network-based surrogate models using the DeePODE framework to enhance simulation efficiency while maintaining accuracy and robustness. Our method replaces conventional stiff ODE solvers with deep learning models trained through evolutionary Monte Carlo sampling from zero-dimensional simulation data, ensuring generalization across varied thermonuclear and hydrodynamic conditions. Tested on 3-species and 13-species reaction networks, the models achieve $\lesssim 1\%$ accuracy relative to semi-implicit numerical solutions and deliver a $\sim 2.6\times$ speedup on CPUs. A temperature-thresholded deployment strategy ensures stability in extreme conditions, sustaining neural network utilization above 75\% in multi-dimensional simulations. These data-driven surrogates effectively mitigate stiffness constraints, offering a scalable approach for high-fidelity modeling of astrophysical nuclear reacting flows.

When binaries are injected into low-angular-momentum orbits around a central supermassive black hole (SMBH), various outcomes can occur, including binary tidal breakup, double stellar disruptions and stellar collision. We use hydrodynamical simulations to study stellar collisions triggered by binary-SMBH encounters, examining both head-on and grazing collisions in deep ($\beta_b=5$) and gentle ($\beta_b=0.6$) encounters, where $\beta_b$ is the ratio of the binary tidal disruption radius to the binary pericenter distance to the SMBH. Head-on collisions consistently result in appreciable mass loss ($\sim 5\%$) and a single merger remnant. Grazing collisions in deep encounters typically leave two strongly disturbed stars with comparable mass loss, while in gentle encounters, multiple collisions eventually produce a single remnant with minimal mass loss ($\lesssim 1\%$). All merger remnants feature extended envelopes, making them susceptible to partial tidal disruptions when they return to the SMBH. The morphology and orbital energy distribution of collision-induced debris differ significantly from those of tidal disruption event (TDE) debris of single stars. Approximately half of the collision-generated debris falls back onto the SMBH, exhibiting a distinct time evolution of the fallback rate. We suggest that such mass loss and fallback can generate electromagnetic flares that mimic weak TDEs.

We present a catalog of Local Universe Near-Infrared Seyfert (LUNIS) \textit{K-}band integral field unit (IFU) data of 88 nearby Active Galactic Nuclei (AGN), curated from SINFONI/VLT and OSIRIS/Keck archival datasets. This catalog includes both type 1 and 2 Seyfert AGN probed down to scales of tens of parsecs with z $<$ 0.02 and spanning over five orders of magnitude in L$_{14-195keV}$ AGN luminosity. As part of this catalog we make publicly available for all galaxies the processed datacubes, a central 200 pc integrated spectrum, and two-dimensional maps of flux, velocity, and velocity dispersion for H$_2$ 1-0 S(1) 2.1218 $\mu$m, [Si VI] 1.9641 $\mu$m, and Br-$\gamma$ 2.1655 $\mu$m. The morphology and geometry of [Si VI], a tracer of AGN outflows, are reported for the 66$\%$ of galaxies with extended emission. We utilize this large sample to probe the behavior of molecular and ionized gas, identifying trends in the properties of the circumnuclear gas (surface brightness and velocity dispersion) with fundamental AGN properties (obscuration and X-ray luminosity). While there is significant variation in circumnuclear gas characteristics across the sample, we find molecular hydrogen to be less centrally concentrated and exhibit lower velocity dispersion relative to ionized gas. In addition, we find elevated molecular hydrogen surface brightness and decreased [Si VI] velocity dispersion in obscured relative to unobscured AGN. The [Si VI] and Br-$\gamma$ emission scale with L$_{14-195keV}$ X-ray luminosity, which, along with the elevated velocity dispersion compared to the molecular gas, verifies an association with AGN outflow processes.

We study the reheating phase following inflation in the context of single-field models, focusing on the perturbative decay of the inflaton into lighter particles. A general analytical framework is presented to compute the reheating temperature $T_{re}$ and related quantities by combining cosmological observations with model-dependent parameters. We derive expressions for $T_{re}$ for three types of interactions: gravitational, scalar, and Yukawa-type fermionic couplings, and apply these results to the class of $\alpha$-attractor inflationary models, which exhibit attractor behavior in the $(n_s, r)$ plane. The main goal of this work is to investigate how key cosmological quantities such as $T_{re}$, $N_{re}$, and $m_\phi$ among others, evolve with the scalar spectral index $n_s$ and the Yukawa coupling constant $y$, within a consistent analytical framework. Although the formulas used are approximate, they are sufficient to capture the qualitative behavior of the relevant quantities across a wide range of parameter values. Here, we are not interested in precise numerical approximations or data analysis, but rather in understanding the general trends and dependence of cosmological quantities of interest. In particular, tendencies observed in the figures, such as the sensitivity of $T_{re}$ to the coupling strength and the equation-of-state parameter $\omega_{re}$, reflect physical features that are not strongly affected by the approximations involved.

In the era of JWST, observations of hot Jupiter atmospheres are becoming increasingly precise. As a result, the signature of limb asymmetries due to temperature or abundance differences and the presence of aerosols can now be directly measured using transmission spectroscopy. Using a grid of general circulation models (GCMs) with varying irradiation temperature (1500 K - 4000 K) and prescriptions of cloud formation, we simulate 3D ingress/egress and morning/evening-limb transmission spectra. We aim to assess the impact that clouds, 3D temperature structure, and non-uniform distribution of gases have on the observed spectra, and how these inhomogeneities can be identified. A second goal is to assess the relative merits of two separate methods (ingress/egress v.s. morning/evening-limb spectroscopy) for isolating atmospheric asymmetries. From our models, it is evident that an east-west temperature difference is the leading order effect for producing ingress/egress or morning/evening-limb spectral differences. We additionally find that clouds contribute strongly to the observed limb asymmetry at moderate irradiation temperatures in our grid ($\sim 2000 \mathrm{K} < T_{\mathrm{irr}} < 3500 \mathrm{K}). At lower temperatures clouds equally dominate the optical depth on both limbs, while at higher temperatures the entire terminator region remains cloud-free. We develop limb asymmetry metrics that can be used to assess the degree of east-west asymmetry for a given planet and predict trends in these metrics with respect to irradiation temperature that are indicative of various physical processes. Our results are useful for predicting and diagnosing the signatures of limb asymmetries in JWST spectra.

We investigate the relationship between solar coronal holes and open-field regions using three-dimensional radiative magnetohydrodynamic (MHD) simulations combined with remote-sensing observations from the Solar Dynamics Observatory (SDO). Our numerical simulations reveal that magnetically open regions in the corona can exhibit brightness comparable to quiet regions, challenging the conventional view that open-field regions are inherently dark coronal holes. We find that the coronal brightness is primarily determined by the total energy input from photospheric magnetic activities, such as the small-scale dynamo, rather than differences in dissipative processes within the corona. Using synthesized EUV intensity maps, we show that brightness thresholds commonly used to identify coronal holes may overlook open-field regions, especially at lower spatial resolutions. Observational analysis utilizing SDO/HMI and AIA synoptic maps supports our simulation results, demonstrating that magnetic field extrapolation techniques, such as the Potential Field Source Surface (PFSS) model, are sensitive to the chosen parameters, including the source surface height. We suggest that discrepancies in estimates of open magnetic flux (the ''open flux problem'') arise both from the modeling assumptions in coronal magnetic field extrapolation and systematic biases in solar surface magnetic field observations. Our findings indicate the need for reconsidering criteria used to identify coronal holes as indicators of open-field regions to better characterize the solar open magnetic flux.

This paper presents the results of a detailed timing and spectral analysis of the TeV-detected blazar 1ES 1218+304, focused on the observations performed with the different instruments onboard the Neil Gehrels Swift Observatory in the period 2005-2024. The source showed various strengths of X-ray flaring activity and 0.3-10\,keV states differing by a factor up to 20 in brightness, exceeding a level of 2.7$\times$10$^{-10}$erg cm$^{-2}$s$^{-1}$ and representing the 3rd brightest blazar during the strongest flare. We detected tens of intraday variability instances, the majority of which occurred on sub-hour timescales and were consistent with the shock-in-jet scenario. The spectral properties were strongly and fastly variable, characterized by a frequent occurrence of very hard photon indices in the 0.3-10 keV and Fermi 0.3-300 GeV bands. The source exhibited very fast transitions of logparabolic-to-powerlaw spectra or conversely, possibly caused by changes of magnetic field properties over small spatial scales or by turbulence-driven relativistic magnetic reconnection. We detected various spectral features, which demonstrate the importance of the first-order Fermi mechanism operating by the magnetic field of changing confinement efficiencies and by the electron populations with different initial energy distributions, stochastic acceleration and cooling processes. In some periods, the source showed a softening at higher GeV-band energies, possibly due to the inverse-Compton upscatter of X-ray photons in the Klein-Nishina regime reflected in the positive correlation between X-ray and high-energy emissions.

Protoplanetary disks around luminous young A-type stars are prime observational laboratories to determine the abundances of complex organic molecules (COMs) present during planet formation. In contrast to their lower stellar mass counterparts, these warmer disks contain the sublimation fronts of complex molecules such as CH3OH on spatial scales accessible with the Atacama Large Millimeter/submillimeter Array (ALMA). We present ALMA observations of the Herbig Ae disk HD 100453 that uncover a rich reservoir of COMs sublimating from the dust cavity edge. In addition to CH3OH, we detect 13CH3OH for the first time in a Class II disk, revealing a factor of three enhancement of 13C in the disk large organics. A tentative detection of CH2DOH is also reported, resulting in a D/H of 1-2%, which is consistent with the expected deuterium enhancement from the low temperature CH3OH formation in molecular clouds and with the deuteration of CH3OH measured in comets. The detection of methyl-formate (CH3OCHO), at only a few percent level of CH3OH is an order of magnitude lower compared to claims towards other organic-rich Herbig Ae disks but is more in line with organic abundance patterns towards the earlier stages of star formation. Together these data provide multiple lines of evidence that disks, and therefore the planet and comet-forming materials, contain inherited interstellar ices and perhaps the strongest evidence to date that much of the interstellar organic ice composition survives the early stages of planet formation.

We report the first X-ray and radio polarimetric results of the neutron star (NS) low-mass X-ray binary (LMXB) atoll-source 4U 1728-34 using the Imaging X-ray Polarimetry Explorer (IXPE) and Australia Telescope Compact Array (ATCA). We discovered that the X-ray source was polarized at PD = 1.9 +/- 1.0% (3-sigma errors) with a polarization angle of PA = -41 +/- 16 degree (3-sigma errors). Simultaneous Neutron Star Interior Composition Explorer (NICER) observations show that the source was in a relatively hard state, marking it as the first IXPE observation of an NS atoll source in the hard state. We do not detect any significant linear polarization (LP) in the radio band, with a 3-sigma upper limit of 2% at 5.5 GHz and 1.8% at 9 GHz. Combining the radio datasets provides the deepest upper limits on the radio polarization at < 1.5% on the linear and circular polarization (measured at 7.25 GHz). The X-ray polarimetric results suggest a source geometry with a Comptonization component possibly attributed to a boundary layer (BL) emission reflected off the disk, consistent with the other NS atoll sources.

We investigate the presence of supermassive black hole (SMBH) binary signatures and the feasibility of identifying them through X-ray reflection spectra. The X-ray emitting region is modeled as a set of two mini-disks bound to the individual SMBHs separated by 100 $GM/c^2$ and the spectra calculated as a function of the mass, mass ratio, and total accretion rate of the binary. The X-ray reflection features are strongly influenced by the accretion-inversion phenomenon expected in SMBH binaries, which results in a wide range of ionization conditions in the two mini-disks. These are imprinted in the resulting composite spectra and the double-peaked and time-variable relativistic Fe K$\alpha$ line profiles. To test whether these features can be used as evidence for the presence of an SMBH binary, we fit mock 100\,ks observations with a single AGN model. For a $10^9$ $M_\odot$ binary targeted by Pulsar Timing Arrays (PTAs), at $z=0.1$ the single AGN model clearly fails to fit the data, while at $z=1$ the fit is acceptable but unable to converge on the SMBH spin. For a $10^6$ $M_\odot$ binary, a progenitor of a \textit{Laser Interferometer Space Antenna} (\textit{LISA}) source, spectral fitting is only possible at $z=0.1$, with the outcomes similar to the PTA binary at $z=1$. We also find that PTA binaries can be expected to show a distinct X-ray spectral variability in multi-epoch observations, whereas for \textit{LISA} precursors, orbital averaging results in the loss of spectral variability signatures.

Hydrogen sulfide (H2S) is thought to be an important sulfur reservoir in interstellar ices. It serves as a key precursor to complex sulfur-bearing organics, and has been proposed to play a significant role in the origin of life. Although models and observations both suggest H2S to be present in ices in non-negligible amounts, its sublimation dynamics remain poorly constrained. In this work, we present a comprehensive experimental characterization of the sublimation behavior of H2S ice under astrophysically-relevant conditions. The sublimation behavior of H2S was monitored with a quadrupole mass spectrometer (QMS) during temperature-programmed desorption (TPD) experiments. These experiments are used to determine binding energies and entrapment efficiencies of H2S, which are then employed to estimate its snowline positions in a protoplanetary disk midplane. We derive mean binding energies of 3159\pm46 K for pure H2S ice and 3392\pm56 K for submonolayer H2S desorbing from a compact amorphous solid water (cASW) surface. These values correspond to sublimation temperatures of around 64 K and 69 K in the disk midplane, placing its sublimation fronts at radii just interior to the CO2 snowline. We also investigate the entrapment of H2S in water ice and find it to be highly efficient, with ~75-85% of H2S remaining trapped past its sublimation temperature for H2O:H2S mixing ratios of ~5-17:1. We discuss potential mechanisms behind this efficient entrapment. Our findings imply that, in protoplanetary disks, H2S will mostly be retained in the ice phase until water crystallizes, at radii near the water snowline, if it forms mixed into water ice. This has significant implications for the possibility of H2S being incorporated into icy planetesimals and its potential delivery to terrestrial planets, which we discuss in detail.