The Ghana Radio Astronomy Observatory (GRAO) marks a pivotal advance in African radio astronomy through the successful transformation of a decommissioned 32 m satellite communication antenna into a scientifically capable, VLBI-ready radio telescope. Strategically located near the equator at Kutunse, Ghana, the telescope offers nearly full-sky coverage (-77 degrees to +88 degrees declination), making it a valuable asset for time-domain astronomy, transient surveys, and global VLBI networks. This work documents the technical evolution of the facility, including beam-waveguide optics, dual-polarization C-band receivers (5 and 6.7 GHz), and recent backend upgrades culminating in the integration of a hydrogen maser, wideband ROACH2 system, and enhanced control and pointing infrastructure. We report early science results from high-resolution spectral-line observations of 6.7 GHz Class II methanol masers, pulse timing of PSR J0835-4510 (Vela), and successful VLBI fringe detections on intercontinental baselines. Simulations and commissioning tests confirm high aperture efficiency (>77%), low sidelobe levels, and robust time stability across the signal chain. These outcomes validate the GRAO's readiness for both standalone and networked operations. As the first operational node in West Africa contributing to the African VLBI Network, GRAO plays a critical role in advancing the continent's participation in global radio astronomy, capacity building, and the preparatory phase of the Square Kilometre Array.

Active galactic nucleus (AGN) powered jets can accelerate cosmic ray electrons, leading to the observed radio synchrotron emission. To simulate this emission, jet dynamics in galaxy clusters must be coupled to electron spectral modelling. We run magneto-hydrodynamic (MHD) simulations of a single AGN jet outburst in a Perseus-like galaxy cluster and adopt a sub-grid model for the acceleration of cosmic ray protons and electrons at unresolved internal shocks in the jet. We evolve cosmic ray electron spectra along Lagrangian trajectories using the Fokker-Planck solver Crest and compute the non-thermal emission using Crayon+. The resulting total electron spectrum reaches a steady-state slope at high momenta, with a gradually decreasing normalization over time, while the lower-momentum portion continues to resemble a freely cooling spectrum. The interaction of the jets with the turbulent cluster environment inflates lobes which rise buoyantly, induce amplification of the magnetic fields and uplift old cosmic ray populations in the wake of the bubbles. We connect radio spectral indices to electron injection ages: at a given radio frequency, weaker magnetic fields are illuminated by higher momenta electrons, whose age is determined by the last injection event. On the other hand, stronger magnetic fields are illuminated by lower momenta electrons, whose age is determined by the maximum energy injection event in the past. This powerful approach allows us to relate the underlying MHD properties to electron spectra and the resulting radio synchrotron emission, thereby enabling us to infer the underlying physics from observed radio properties.

Notoriously hard to detect and study, isolated neutron stars (NS) could provide valuable answers to fundamental questions about stellar evolution and explosion physics. With the upcoming Roman Space Telescope, scheduled for launch in 2026, a new and powerful channel for their detection - astrometric microlensing - will become available. We set out to create a realistic sample of simulated gravitational microlensing events as observed by Roman with the Galactic Bulge Time Domain Survey. We focus in particular on the population of NS lenses, which has until now been largely understudied. We use state-of-the-art Galactic models tailored for application to microlensing by compact objects. We simulate four different NS populations with Maxwellian natal kick distributions: $\bar{v} = (150, \ 250, \ 350, \ 450)$ km/s. We apply projected Roman precision, cadence, and detectability criteria. We find the parameter space $\log_{10} t_{\rm E}$ - $\log_{10} θ_{\rm E}$, which will be accessible to Roman observations, to be maximally efficient for classification of stellar remnants. We find a feature in this space that is characteristic to NS; using this feature, optimal samples of NS candidates can be constructed from Roman-like datasets. We describe the dependence of observable parameter distributions on the assumed mean kick velocities. As the effects of natal kicks are very complex and mutually counteracting, we suggest more detailed studies focused on the dynamics of NS are needed in anticipation of Roman and future surveys. We estimate Roman will observe approximately $11\,000$ microlensing events - including $\sim100$ with NS lenses - whose both photometric and astrometric signal are detectable; the event yield decreases by $38\%$ if gap-filling low-cadence observations are not included. We make all simulated microlensing event datasets publicly available in preparation for Roman data.

Characterizing exoplanet host stars at a population level requires a method of homogeneously characterizing stellar properties across all spectral types. To this end, we have developed Metal Pipe, a new code for determining stellar parameters and abundances, which is designed for use across a wider range of spectral types than many commonly used codes. It combines the widely-used package MOOG with photometric stellar parameters, a user-supplied high-resolution spectrum, and a newly curated list of spectral lines. Metal Pipe outputs values for $T_{\rm{eff}}$, $\log{(g)}$, $M_*$, $R_*$, and $L_*$ from isochrones, and abundances of C, O, Na, Mg, Al, Si, S, Ca, Ti, and Fe from MOOG. In this paper, we describe the Metal Pipe algorithm and tests of Metal Pipe against previous abundance measurements on archival HIRES spectra of 503 F, G, and K type stars. We find RMS scatters of ~100 K in $T_{\rm{eff}}$, ~0.10 dex in $\log{(g)}$, and ~0.10 dex for all measured abundances. These values are comparable to estimated measurement uncertainties, verifying Metal Pipe for continued use in building a detailed abundance catalog. Future papers in this series will test Metal Pipe's applicability to late K and M dwarf stars, and provide other improvements.

Weak lensing surveys require accurate correction for the point spread function (PSF) when measuring galaxy shapes. For a diffraction-limited PSF, as arises in space-based missions, this correction depends on each galaxy SED. In the Euclid mission, galaxy SED reconstruction, a tasks of the photometric-redshift processing function (PHZ PF), relies on broad- and medium-band ancillary photometry. The limited wavelength sampling of the Euclid VIS passband and signal-to-noise ratio may affect the reconstruction accuracy and translate into biases in the weak lensing measurements. In this study, we present the methodology, which is employed in the Euclid PHZ PF, for reconstructing galaxy SEDs at 55 wavelengths, sampling the VIS passband every 10 nm, and we assess whether it fulfils the accuracy requirements imposed on the Euclid PSF model. We employ both physics- and data-driven methods, focusing on a new approach of template-based flux correction and Gaussian processes, and we introduce an SED metric whose bias propagates into PSF quadrupole moment errors. Our findings demonstrate that Gaussian processes and template fitting meet the requirements only in specific, but complementary, redshift intervals. We therefore propose a hybrid approach, which leverages both methods. This solution proves to be effective in meeting the Euclid accuracy requirements for most of the redshift range of the survey. Finally, we investigate the impact on the SED reconstruction of a new set of 16 evenly-spaced medium-band filters for the Subaru telescope, providing quasi-spectroscopic coverage of the VIS passband. This study shows promising results, ensuring accurate SED reconstruction and meeting the mission PSF requirements. This work thus provides not only the methodological foundation of galaxy SED reconstruction in the Euclid PHZ PF, but also a roadmap for future improvements using a new medium-band survey.

Most LSST extragalactic science will rely on photometric redshifts (photo-$z$) to extract distance information for the galaxies. However, an incomplete or non-representative training set can introduce bias into photo-$z$ estimation. It is necessary to understand how various forms of training set imperfection, such as incompleteness and non-trivial spectroscopic target selection, affect photo-$z$ estimation algorithms, and to identify metrics best-suited to quantify the impact. This work aims to systematically study metrics for diagnosing how various photo-$z$ methods react to certain types of training set incompleteness and non-representativeness. We use methods available through the open-source Python library Redshift Assessment Infrastructure Layers (RAIL) to systematically test the algorithms CMNN, GPz, FlexZBoost, and PZFlow on mock training data degraded in accordance with several existing spectroscopic sky surveys, as well as under conditions of inverse redshift incompleteness, which approximately mimics observed patterns of incompleteness at high redshift. We employ the algorithm TrainZ as a control. Finally, we quantify photo-$z$ algorithm performance using a variety of statistical metrics implemented externally to RAIL. We determine that the Kullback-Liebler Divergence, Wasserstein Distance, and Probability Integral Transform are particularly informative metrics with which to assess the impact of training set imperfection on algorithmic performance. We also find that inverse redshift incompleteness effects alone lack the complexity to realistically represent anticipated training data.

Millimeter-band polarimetry offers a powerful probe of AGN jets, accessing regions less affected by opacity and Faraday rotation than at longer radio wavelengths. As part of the POLAMI program, we have conducted 14 years of 1 mm and 3 mm polarization monitoring of a sample of gamma-ray-bright blazars with the IRAM 30-m telescope, complemented here with long-term optical polarimetric observations from multiple facilities. We aim to test whether current models of parsec-scale jet physics are consistent with observed multi-band polarization behavior. Using a Bayesian framework, we derive intrinsic mean flux densities and modulation indices for total flux and fractional polarization, and characterize EVPA variability using circular statistics. We then examine how these quantities reflecting variability properties across millimeter and optical bands relate to synchrotron peak frequency, jet orientation, and radio/gamma-ray luminosities. BL Lac objects exhibit, on average, higher fractional polarization and lower EVPA variability than FSRQs at all wavelengths. Fractional polarization increases with frequency, consistent with increasingly ordered magnetic fields at shorter wavelengths. BL Lacs also show more frequent alignment of EVPAs between optical and millimeter bands, whereas FSRQs display weaker coherence. EVPA variability correlates positively with radio and gamma-ray luminosities and negatively with synchrotron peak frequency, most strongly in the optical. We further find a positive correlation between EVPA spread and fractional polarization variability, suggesting a direct link between magnetic-field structure and polarization dynamics.

The surface [C/N] of red giants is correlated with birth mass, but not directly impacted by mass loss. Exploiting this, we compare asteroseismic masses of red giants with the same [C/N] and but different evolutionary states. We find bulk differences between stars at the beginning of the red giant branch and in the subsequent evolutionary phase, the red clump, providing a direct constraint on the strength of net RGB mass loss in field stars. We find that net mass loss decreases with metallicity and mass, matching recent studies for field giants, but contradicting expectations from the widely used Reimers' mass loss formula. We propose a mass- and metallicity-dependent Reimers' $η$ calibration that reproduces the empirical trends that we see. In addition, we identify 207 stars (3.33% of our sample) that are clear outliers from their population in these birth mass bins, which we believe are likely candidates for mass transfer events. These stars do not show any obvious discrepancies in abundances or binary properties from their counterparts. This population should be accounted for in Galactic archaeological studies. Further follow-up is required to quantify their occurrence rate and origin.

We present high-resolution Very Large Array (VLA) continuum observations at S-band ($3$ GHz, $560$ pc scale) and X-band ($10$ GHz, $200$ pc scale) of the ram-pressure-stripped Virgo galaxy NGC 4522, to investigate the characteristics of its radio continuum, spectral index, and magnetic field under the influence of the intracluster medium (ICM). The total radio continuum shows an asymmetry that extends northwest, mirroring the HI gas distribution, but showing distinct features in the extraplanar regions. The spectral index steepens systematically from $α\sim-0.6$ in the main disk to $α\sim-1.1$ in the outer disk. We find that the spectral index behavior of the outer disk is mainly due to an ICM shock that can re-accelerate electrons and a significant reduction of thermal emission. Intriguingly, extraplanar clouds exhibit exceptionally flat spectral indices ($α\sim-0.2$ to $0$), resulting from a combination of significantly enhanced thermal emission and pronounced spectral aging of the non-thermal component. Although some of these regions correlate with H$α$, others do not. We propose that the mixing between the ICM and interstellar medium (ISM) is an alternative mechanism that enhances thermal emission independently of star formation. Polarized continuum emissions are highly asymmetric, preferentially distributed along the ICM wind side, and the polarization fraction increases radially outward from the galactic midplane, indicating that the polarized emission is strongly influenced by the ICM wind. Our results show how and where the ICM substantially affects the ISM, and also demonstrate that high-frequency observations are crucial for analyzing the radio continuum of ram pressure stripping galaxies.

We investigate the long-term impact of disc photoevaporation on the dynamical stability and evolution of giant planet pairs in mean motion resonances. Using two-dimensional hydrodynamical simulations with FARGO3D, in which we have included mass-loss due to photoevaporation, we explore a parameter space covering disc mass, viscosity, planet mass, and resonance type. We find that strong photoevaporation depletes gas in the common gap between the planets, slowing migration and suppressing planet-disc interactions that typically lead to resonance breaking and eccentricity damping. This stabilising effect is most significant for 3:2 resonances, which are more prone to disruption due to the reduced planet spacing. In contrast, 2:1 resonances are generally more robust but can still be destabilised at high disc mass and moderate-to-strong photoevaporation due to asymmetric torques. Photoevaporation can therefore stabilise resonances that would otherwise break, or conversely disrupt resonances that are natively more stable. Even in cases where photoevaporation does not directly affect resonance stability, it typically results in increased planetary eccentricities. These results highlight the complex, system-dependent nature of resonance evolution, with implications for the final orbital architectures of giant planet systems and their detectability via astrometry from missions such as Gaia.

We present a comprehensive reanalysis of the dynamical state of the high-redshift galaxy cluster SPT-CL J2215-3537 (z = 1.16), using the full set of available Chandra observations to characterize the thermodynamic and morphological properties of the intracluster medium. Although previously identified as one of the most distant dynamically relaxed systems based on X-ray morphological statistics, we find compelling evidence that SPT-CL J2215-3537 displays some level of dynamical activity. This includes temperature anisotropies consistent with the first detection of a pair of core-sloshing cold fronts at z > 1. We identify a ghost cavity candidate and estimate its mechanical power as log10(Pcav/10^42 erg s^-1) = 2.66 +- 0.23, confirming that radiative cooling strongly exceeds active galactic nucleus feedback heating. We show that SPT-CL J2215-3537 is likely in a short transient phase preceding the onset of a self-regulated cooling-feedback cycle. We recalculate traditional X-ray morphological parameters and discuss how non-self-similar evolution of parameters sensitive to the surface brightness cuspiness can bias dynamical classifications at high redshift.

High-resolution total solar eclipse (TSE) white light (WL) images are the only observations at present to capture coronal structures over an uninterrupted field of view (FoV) of at least 10 solar radii (Rs) starting from the solar limb. They were the first to report the presence of vortex rings originating within the prominence-corona transition region (PCTR). They also captured CMEs and Kelvin-Helmholtz (KH) instabilities at different phases of their evolution. While the evolution of CMEs and KH waves is relatively well-documented, little is known about the survivability of vortex rings beyond the FoV of the TSE images. In this study, we use seven TSE images and non-contemporaneous WL images acquired by the Wide-Field Imager for Parker Solar PRobe (WISPR) to track the spatial evolution of vortex rings, KH waves, and CMEs. The size trend versus radial distance for vortex rings and KH waves are found to be shallower below 1.5 Rs than beyond 3 Rs, while the CMEs observed beyond 3 Rs show a unique slope. The WISPR time series yield an average speed of 249.02 +/- 25.3 km/s for the vortex rings beyond 3 Rs, that when combined with their size yields a speed of 19.39 +/- 3.20 km/s below 1 Rs. These values are remarkably consistent with the acceleration profile of the slow solar wind over the same distance. This study provides strong empirical evidence that vortex rings, which originate at the PCTR with complex magnetic structures, do not dissipate as they expand away from the Sun with the solar wind.

Aims. By analysing the light curves of the ZZ Ceti star WD 1310+583, we aim to determine its pulsational frequencies and to give constraints on the main stellar parameters using the tools of asteroseismology. Methods. We performed the Fourier analysis of the TESS light curves of WD 1310+583 and selected the possible pulsational modes. We also used spectroscopic data collected with the Cosmic Origins Spectrograph of the Hubble Space Telescope to give constraints for the asteroseismic analysis. We perform the latter with period-to-period fits using fully evolutionary white dwarf models. Results. The star presented in this paper shows a particularly large number (41) of pulsational frequencies, which provides a potential opportunity for detailed asteroseismic investigations. We found a mean period spacing of ~40.5 seconds, which allows us to state that the stellar mass of WD 1310+583 would be larger than ~0.57 M_Sun. We also attempted an asteroseismological analysis by performing period-to-period fits, but we were unable to find a single statistically significant asteroseismological solution. We adopted a tentative solution consisting of a white dwarf model with M* = 0.632 M_Sun, Teff = 11 702 K, and an asteroseismic distance d = 27.75 +0.17/-0.15 pc, which is significantly smaller than the one predicted by Gaia (d = 30.79 +/- 0.2 pc). We also determined that the rotational period of our target is 1.18 d.

We determine the post-perihelion rotation period of 3I/ATLAS using two independent diagnostics: the temporal modulation of the position angle (PA) of a persistent jet-like feature, and a time-series photometric light curve in the Gr (R) band. For the jet morphology, we measure the PA at multiple epochs by applying the Larson-Sekanina Rotational Gradient filter to Hubble Space Telescope images between November 20, 2025 and December 27, 2025, and model the phase-folded PA curve with weighted least-squares Fourier series up to two harmonics while scanning trial periods P to identify minima in \c{hi}2(P). For the photometry, we adopt the best-fit period from an independent 30-minute binned analysis (from a 0.25 meter telescope MPC L92) based on a refined \c{hi}2(P) profile for a sinusoidal model with nightly offsets. We find that the jet-PA modulation gives a period Pjet = 7.20 +/-0.05 h (adopting a conservative uncertainty dominated by sparse sampling and systematics), while the photometry yields Pphot = 7.136+/-0.001 h (formal 1σ uncertainty). Although the periods differ slightly, the offset is plausibly attributable to non-Gaussian systematics and aliasing. The combined data supports a post-perihelion rotation period of 7.1 h associated with precession of the jet structure around the rotation axis by 20°. The rotation axis is aligned with the sunward direction to within 20°

Near-infrared (NIR) detectors -- which use non-destructive readouts to measure time-series counts-per-pixel -- play a crucial role in modern astrophysics. Standard NIR flux extraction techniques were developed for space-based observations and assume that source fluxes are constant over an observation. However, ground-based telescopes often see short-timescale atmospheric variations that can dramatically change the number of photons arriving at a pixel. This work presents a new statistical model that shares information between neighboring spectral pixels to characterize time-variable observations and extract unbiased fluxes with optimal uncertainties. We generate realistic synthetic data using a variety of flux and amplitude-of-time-variability conditions to confirm that our model recovers unbiased and optimal estimates of both the true flux and the time-variable signal. We find that the time-variable model should be favored over a constant-flux model when the observed count rates change by more than 3.5%. Ignoring time variability in the data can result in flux-dependent, unknown-sign biases that are as large as ~120% of the flux uncertainty. Using real APOGEE spectra, we find empirical evidence for approximately wavelength-independent, time-dependent variations in count rates with amplitudes much greater than the 3.5% threshold. Our model can robustly measure and remove the time-dependence in real data, improving the quality of data-model comparison. We show several examples where the observed time-dependence quantitatively agrees with independent measurements of observing conditions, such as variable cloud cover and seeing.

The Latin American Giant Observatory (LAGO) is a collaborative initiative that deploys a network of low-cost, autonomous Water Cherenkov Detectors across Latin America and Spain. Initially focused on detecting gamma-ray bursts at high-altitude sites, LAGO has evolved into a multidisciplinary forum for astroparticle physics, space weather studies, and environmental monitoring. Its detectors operate from sea level to over 4300 meters above sea level (m a.s.l.) in diverse geomagnetic and atmospheric conditions. The ARTI-MEIGA simulation framework is a key development that models the entire cosmic-ray interaction chain, enabling site-specific simulations to be integrated into FAIR-compliant workflows. LAGO also plays a significant role in regional education and training through partnerships with ERASMUS+ projects, positioning itself as a hub for research capacity building. New contributions emerging from the collaboration include volcano muography, neutron hydrometry for precision agriculture, and space weather monitoring in the South Atlantic Magnetic Anomaly. LAGO demonstrates how Cherenkov-based detection and open science can drive scientific discovery and practical innovation.

The transient and variable optical sky is relatively poorly characterised on fast ($<$1$\,$hr) timescales. With the Dark Energy Camera (DECam), the Deeper, Wider, Faster programme (DWF) probes a unique parameter space with its deep (median of $g\sim22.2$ AB mag), minute-cadence imaging. In this work, we present DWF's first data release which comprises high cadence photometry extracted from $\sim$12000 images and 166 hours of telescope time. We present a novel data processing pipeline, $\texttt{dwf-postpipe}$, developed to identify sources and extract their light curves. The accuracy of the photometry is assessed by cross-matching to public catalogues. In addition, we injected a population of synthetic GRB afterglows into a subset of the DWF DECam imaging to compare the efficiency of our pipeline with a standard difference imaging approach. Both pipelines show performance and reliably recover injected transients with peak magnitudes $g<22$ AB mag with an efficiency of $97.24^{+0.7}_{-1.0}$ percent for \texttt{dwf-postpipe} and $96.14^{+0.9}_{-1.1}$ percent for a difference imaging approach. However, we find that $\texttt{dwf-postpipe}$ is less likely to recover transients appearing in galaxies that are brighter or comparable in brightness to the transient itself. To demonstrate the power of the data in this release, we conduct a search for uncatalogued variable stars in a single night of DWF DECam imaging and find ten pulsating variables, two eclipsing binaries and one ZZ ceti. We also conduct a search for variable phenomena in the Chandra Deep Field South, a Rubin deep drilling field, and identify two flares from likely UV ceti type stars.

Brown dwarfs that gain mass through binary interactions may be pushed above the boundary that divides brown dwarfs from low-mass stars: the hydrogen burning limit (HBL). Some of these objects will make their way to the main sequence and may eventually be indistinguishable from ordinary low-mass stars, while others will remain brown dwarf-like, unable to burn hydrogen at a high enough rate to power their surface luminosity. We study the evolution of both types of object to provide a taxonomy and testable observational predictions for these objects depending on their evolutionary path. Using MESA simulations, we find that a subset of the objects that will eventually become stars experience an extended luminosity plateau, where their surface luminosity remains nearly constant on 100 Myr - Gyr timescales. We find that the plateau timescale is set by the amount of energy required to re-heat the cores of these objects to a level sufficient to sustain convection. The timescales required for the cores of these objects to "unfreeze" and arrive at the main sequence is long enough that surveys may be able to find objects in this evolutionary stage. These objects, along with those that never reach the main sequence, occupy a unique space in a mass-luminosity diagram, and would provide a unique constraint on binary mass transfer physics.

We presented a comprehensive multi-epoch timing and multiwavelength analysis of the accreting millisecond X-ray pulsar MAXI J1957+032, covering two major outbursts in 2022 and 2025. By reanalyzing the 2022 outburst data from the Neutron Star Interior Composition Explorer (NICER), we found the spin frequency and orbital parameters from the observations in 0.3-5 keV. For the 2025 outburst, we reported the detection of pulsations with the Einstein Probe (EP). Based on the $\sim$3-year baseline between these two outbursts, we measured a significant long-term spin-down rate of $\dotν= (-5.73 \pm 0.28) \times 10^{-14}~{\rm Hz~s^{-1}}$. Assuming that the quiescent spin-down is driven by magnetic dipole radiation, we inferred a spin-down luminosity of $L \approx 1.1 \times 10^{36}~{\rm erg~s^{-1}}$ and a surface dipolar magnetic field of $B \approx (7.3 - 10.4) \times 10^8$ G. Furthermore, we conducted a deep radio pulsation search with the Five-hundred-meter Aperture Spherical radio Telescope (FAST) during the X-ray quiescent state in 2024, resulting in a non-detection with a 7$σ$ flux density upper limit of 12.3 $μ$Jy. This corresponds to a radio efficiency upper limit of $ξ< 2.8 \times 10^{-10}$, which is significantly lower than that of typical millisecond pulsars with a similar spin-down power. This profound radio pulsation faintness can be explained by two primary scenarios: either a geometric effect, wherein the pulsar's radio beam is directed away from our line of sight, or a physical suppression of the emission mechanism, potentially caused by a persistent low-level accretion flow during the X-ray quiescent state.

Context. We investigate the physics of black hole accretion flows, particularly focusing on phenomena like magnetic reconnection and plasmoid formation, which are believed to be responsible for energetic events such as flares observed from astrophysical black holes.Aims. We aim to understand the influence of radiative cooling on plasmoid formation within black hole accretion flows that are threaded by multi-loop magnetic field configurations.Methods. We conducted two- and three-dimensional two-temperature general relativistic magnetohydrodynamic (GRMHD) simulations. By varying the magnetic loop sizes and the mass accretion rate, we explored how radiative cooling alters the accretion dynamics, disk structure, and the properties of reconnection-driven plasmoid chains.Results. Our results demonstrate that radiative cooling suppresses the transition to the magnetically arrested disk (MAD) state by reducing magnetic flux accumulation near the horizon. It significantly modifies the disk morphology by lowering the electron temperature and compressing the disk, which leads to increased density at the equatorial plane and decreased magnetization. Within the current sheets, radiative cooling triggers layer compression and the collapse of plasmoids, shortening their lifetime and reducing their size, while the frequency of plasmoid events increases. Moreover, we observe enhanced negative energy-at-infinity density in plasmoids near the ergosphere, with its peaks corresponding to plasmoid presence.Conclusions. Radiative cooling plays a critical role in shaping both macroscopic accretion flow properties and microscopic reconnection phenomena near black holes. This suggests that radiative cooling may modulate black hole energy extraction through reconnection-driven Penrose processes, highlighting its importance in models of astrophysical black holes.

The active impedance is a fundamental parameter for characterizing the behavior of large, uniform phased array antennas. However, its conventional calculation via the mutual impedance matrix (or the scattering matrix) offers limited physical intuition and can be computationally intensive. This paper presents a novel derivation of the active impedance directly from the radiated beam pattern of such arrays. This approach maps the scan-angle variation of the active impedance directly to the intrinsic angular variation of the beam, providing a more intuitive physical interpretation. The theoretical derivation is straightforward and rigorous. The validity of the proposed equation is conclusively confirmed through full-wave simulations of a prototype array. This work establishes a new and more intuitive framework for understanding, analyzing and accurately measuring the scan-dependent variations in phased arrays, which is one of the main challenges in modern phased array designs. Consequently, this novel formalism is expected to expedite and simplify the overall design and optimization process for next-generation, large-scale uniform phased arrays.

Dust grains in the interstellar medium interact with photons across the electromagnetic spectrum. They are generally photon energy converters, absorbing short wavelength radiation and emitting long wavelength radiation. Sixty years ago in 1965, thermal emission from dust grains in the interstellar medium was discovered. This tutorial is a summary of the physics of thermal dust continuum emission and how to use observations of the intensity and flux density of dusty objects to calculate physical properties such as mass, column density, luminosity, dust temperature, and dust opacity spectral index. Equations are derived, when feasible, from first principles with all limits and assumptions explicitly stated. Properties of dust opacities appropriate for different astrophysical environments (e.g. diffuse ISM, dense cores, protoplanetary disks) are discussed and tabulated for the wavelengths of past, current, and future bolometer cameras. Corrections for observations at high redshift as well as the effects of telescope measurement limitations are derived. We also update the calculation of the mean molecular weight in different ISM environments and find that it is 1.404 per H atom, 2.809 per H2 molecule, and 2.351 per gas particle assuming protosolar metallicity and the latest values of the ISM gas phase abundances of metals.

The speed of sound refers to the rate at which information travels from one point to another. It is a positive quantity and bounded by causality. It is defined as the rate of change of pressure with respect to the system's density. In this article, we derive a covariant equation for the sound wave and demonstrate how the wave equation is modified in the general relativistic formalism. One can then define an effective speed of sound by attenuating the usual definition of sound speed with the gravitational metric potential. The general relativistic curvature effect is observed to reduce the speed of sound when computed inside a neutron star. This effectively makes the star relatively softer (according to the equation of state). The change in the effective sound speed can be easily visualised if one redefines the non-radial modes in terms of it. The modes do not change, but the space-time curvature reduces the amplitude of the oscillation modes. The formalism is suited for studying astrophysical compact objects.

We present the neutral gas morphology of four galaxies from z = 0.22 to 0.47 obtained with the COSMOS HI Large Extragalactic Survey (CHILES). The HI is resolved at the highest redshift with the 7.5 arcsec beam of CHILES and 43 kpc linear scale, with all four galaxies having extended HI. Three are massive galaxies (Mstellar > 3 e10 Mo), with HI masses of 1.6 - 6.7 e10 Mo, and active star formation (3 - 30 Mo/yr). The morphology and kinematics of the galaxies vary from regular to disturbed, including an asymmetric HI disk surrounding the fourth smaller galaxy (Mstellar ~ e9 Mo). CO(1-0) observations of the sample, obtained with the LMT, confirm the redshifts of three of the four galaxies and we derive H2 masses of 0.4 - 5.2 e10 Mo. JWST imaging with four combined NIRCam filters reveals disturbed stellar components with compact knots in two of the galaxies. We combine our new higher-redshift galaxies with previously published observations to conduct a more complete study of HI and H2 evolution in the redshift range 0 - 0.5. With our HI flux-limited observations compared to similar lower redshift galaxies with high stellar mass (Mstellar > e10 Mo), the results show the mean H2/HI ratio at the highest redshift is 10.3 +- 3.4 larger than the mean H2/HI ratio in the local Universe.

The Gamma-ray Burst Monitor (GBM) on board Fermi Gamma-ray Space Telescope has produced the largest database of all-sky observations in gamma rays with its continuous data with high time and energy resolutions. These data contain a wealth of unidentified transient events that did not trigger the detectors for various reasons. We conducted extensive searches to identify such untriggered transient events observed with GBM in 11 years (July 2010 - June 2021). In particular, we employed four different search modes with various energy ranges (mainly below 300 keV) and time resolutions (from 8 ms to 2 s), utilizing three statistical methods (signal-to-noise ratio, Poisson, and Bayesian statistics), each with different effectiveness in identifying specific classes of transients. Moreover, we developed algorithms for known-event flagging as well as unknown-event classification for our candidate events found in the searches. In this paper, we present our search methodologies, event flagging and classification algorithms and the resulting comprehensive event catalog. The catalog contains more than a million events in total, including known events such as gamma-ray bursts, soft-gamma repeater bursts, galactic X-ray source activities, terrestrial gamma flashes, and solar flares. For each candidate event, the catalog presents the event time, detection significance, event duration, hardness ratios, known-event flagging results, and classification probabilities. Our short-transient catalog significantly expands the currently-existing list of known events and complements the GBM trigger catalog. The event database with filtering capabilities is also publicly available at https://magnetars.sabanciuniv.edu/gbm, which allows users to retrieve event information based on their input queries along with the event lightcurves.

Galaxy cluster-scale strong gravitational lensing systems are rare yet valuable tools for investigating the properties of dark matter and dark energy, as well as providing the opportunity to study the distant universe at flux levels and spatial resolutions that would otherwise be unavailable. Large-scale imaging surveys present unprecedented opportunities to expand the sample of cluster lenses. In this study, we adopt a deep learning-based approach to identify cluster lenses from the DESI Legacy Imaging Surveys, utilizing the catalog of galaxy cluster candidates identified by Zou et al. (2021). Our lens-finder employs a ResNet-18 architecture, trained with mock images of cluster lenses as positives and observational images of cluster scale non-lenses as negatives. We do an iterative operation to increase the completeness of our work, namely adding the found true positive samples back to the training set and training again for several times. Human inspection is conducted to further refine the candidates, categorizing them into grades (A, B, C) according to the significance of the strongly lensed arcs. Reviewing all 540,432 objects in Zou's catalog, we discover 485 high-confidence cluster lens candidates with a cluster $M_{500}$ range of $10^{13.67\sim14.97}M_{\odot}$ and a Brightest Central Galaxy (BCG) redshift range of $0.04\sim0.89$. After excluding the lens candidates listed in previous studies, we identify 247 newly discovered cluster lens candidates, including 16 grade A, 90 grade B, and 141 grade C. This catalog of cluster lens candidates is publicly available online, and follow-up observations are encouraged to confirm and conduct thorough investigations of these systems.

Recent JWST observations of Lyman-$α$ emission at $z \sim 11-6$ indicate a rapid reionization of the intergalactic medium within the first $\sim700$ Myr. The required Lyman continuum (LyC) photon budget may naturally arise from the unexpectedly high galaxy number densities revealed by JWST, reducing the need for scenarios invoking very high LyC escape fractions ($f_{\rm esc}\gtrsim0.2$) or dominant contributions from ultra-faint galaxies ($M_{\rm UV}>-15$) in the standard $Λ$CDM framework. In this work, we model the reionization history under the Early Dark Energy (EDE) paradigm -- originally proposed to ease the Hubble tension -- which also explains the observed over-abundance of high-$z$ galaxies without extreme star formation efficiencies. The EDE model yields reionization histories consistent with current constraints while requiring only moderate LyC escape fractions and UV luminosity densities ($f_{\rm esc}\sim 0.05-0.1$, $M_{\rm UV}\lesssim -17$ to $-15$). Our results suggest that, once key astrophysical parameters are better constrained, the reionization history could serve as an independent and complementary probe of EDE cosmologies.

The Main Aim of this paper is to explain the emergence of new components of pulsars at higher radio bands by implementing the Inverse Compton Scattering Mechanism. From pulsar radio observation, it is seen that a couple of pulsars reveal new emission components at higher radio frequencies, although they show single-component emission at lower frequencies. We develop a brief outline, fostering inverse Compton scattering (ICS) of the low-frequency radio photons as a vulnerable source of scattering, susceptible to explaining the evolution of new components of some radio pulsars at higher bands. We couple the conventional curvature radiation (CR) mechanism and ICS, and suggest that the spectral convolution of the flux component individually from CR and the modulated template due to the ICS scattered component can be combined to reproduce such signatures associated with the diverse morphology of the integrated pulse profile. We reproduce the beam frequency diagram, the geometrical variation of different parameters of the emission geometry, as well as the multi-frequency evolution from theory. We have suitably tuned the input parameter space and given the combination of parameters that can tune to a particular scattered frequency in tabulated form. We conclude that ICS may be a responsible process for describing the emergence of new components in higher radio emission bands.

Pulsar wind nebula DA~495 (G65.7+1.2) has been extensively observed from radio to TeV $γ$-ray bands. We present LHAASO observations of DA~495, revealing an energy-dependent morphology, where an extended source with $r_{39}=0.19^{\circ}\pm0.02^{\circ}$ is detected by WCDA (0.4-15~TeV), and a point-like source with a 95\% upper limit of $r_{39}=0.11^{\circ}$ is observed by KM2A ($>25~\mathrm{TeV}$). The spectrum of the source extends beyond 100~TeV with a break or cutoff at a few tens of TeV. Our X-ray data analysis, based on Chandra and XMM-Newton observations, shows that the X-ray emission of DA~495 extends well to $\sim 6^{\prime}$, significantly larger than the size previously reported. The broadband spectral energy distribution across radio, X-ray and TeV $γ$-ray bands is phenomenologically described by a one-zone leptonic model, yielding an average magnetic field of $\sim$ 5 $\mathrm{μG}$, while Fermi-LAT spectral analysis indicates a likely presence of a $γ$-ray pulsar within the system. A time-dependent model, in which particle transport is convection-dominated in the inner region (within $\sim100^{\prime\prime}$) and diffusion-dominated in the outer region, successfully reproduces the observed radial profiles of X-ray surface brightness and spectral index, and also accounts for the TeV $γ$-ray emission detected by LHAASO, suggesting that DA~495 represents an evolved PWN with ongoing particle escape that gives rise to a TeV halo component -- that is, a PWN+halo system.

Potential Field Source Surface (PFSS) models are widely used to study the solar corona and form the basis for solar wind forecasting, yet often fail to reproduce observed properties of coronal holes. We analyze 702 observed coronal holes between 2010 and 2019 and compute corresponding PFSS magnetic field extrapolations to examine their magnetic topology and loop statistics, comparing them with quiet Sun regions. Our goal is to determine how observed coronal holes are represented in a PFSS model and to identify sources of known discrepancies. We find that low-lying loops covering the weak, balanced background field in coronal holes are statistically smaller and narrower than in quiet Sun regions, with a median height strongly correlated to the coronal holes mean magnetic flux density (cc_Pearson = 0.81). This suggests that at low altitudes, the coronal hole magnetic topology is primarily governed by its flux density, unlike in quiet Sun regions. Coronal holes also contain loops extending much higher into the corona than typical quiet Sun loops, although it is unclear if these are truly closed or reflect source surface height limitations. Overall, differences in modeled magnetic structures of coronal holes and quiet Sun regions are evident, even when the PFSS model does not indicate any open fields. These results suggest that observed coronal holes correspond to distinct photospheric magnetic structures, and that discrepancies with PFSS models reflect modeling limitations rather than the absence of coronal holes.

We analyze several key rest-optical emission-line ratios in a sample of 763 galaxies as well as composite spectra from JADES DR3 in the range $1.4 < z < 7$. These emission-line ratios include: [O III]$\lambda5008$/H$β$, [N II]$λ6585$/H$α$, [S II]$λλ6718,6733$/H$α$, [O I]$λ6302$/H$α$, O32, R23, Ne3O2, and RO2Ne3. We find evidence for a harder ionizing spectrum at $z\sim 3.5$ compared to $z\sim 2$ at fixed gas-phase metallicity, resulting in a pronounced shift in the star-forming galaxy locus on the [N II]/H$α$ BPT diagram and the O32 vs. R23 diagram. At $z\gtrsim 3.5$, star-forming galaxies occupy a common locus, indicating that ISM ionizing conditions at fixed gas-phase metallicity do not evolve strongly at these early cosmic times. There is a connection between ISM ionizing conditions and the chemical abundance patterns (i.e., $α$/Fe) in massive stars providing the ionizing radiation field. Therefore, the lack of evolution in ISM ionizing conditions at $z\gtrsim 3.5$, followed by evolution towards a softer ionizing spectrum at fixed nebular metallicity as cosmic time proceeds to $z\sim 2$ and lower redshift mirrors the chemical abundance patterns in Milky Way stars as a function of iron abundance. Our results highlight the diagnostic power of emission-line diagrams in the era of JWST to further our understanding of the ISM conditions into the Epoch of Reionization.

We present the Atacama Large Millimeter/submillimeter Array (ALMA) observations of linearly polarized 870 $μ$m continuum emission at a resolution of $\sim$0.2$^{\prime\prime}$ (2000 au) toward the two massive clumps, Clump 1 and Clump 4, in the 20 km s$^{-1}$ cloud. The derived magnetic field strengths for both clumps range from $\sim$0.3 to 3.1 mG using the Angular Dispersion Function (ADF) method. The magnetic field orientations across multiple scales suggests that the magnetic field dominates at the cloud scale, whereas gravity likely governs the structures at the core (0.01$-$0.1 pc) and condensation ($\le$ 0.01 pc) scales. Furthermore, the study on the angular difference between the orientations of the local gravity gradient and the magnetic field suggests that the magnetic field predominantly governs the dynamics in the diffuse regions, while gravity and star formation feedback become increasingly significant within the dense regions. The ratio of the magnetic field tension force $F_\textrm{B}$ to the gravitational force $F_\textrm{G}$ suggests that the magnetic field may provide some support against gravity, but it is insufficient to prevent gas from infalling toward the dense cores.

The first four all-sky surveys with eROSITA the soft X-ray instrument on board the Spektrum-Roentgen-Gamma (SRG) satellite revealed a new X-ray source, eRASSU J012422.9-724248, in the Magellanic Bridge, near the Eastern Wing of the Small Magellanic Cloud (SMC). We performed a broadband timing and spectral analysis using the optical and X-ray data of eRASSU J012422.9-724248. Using the X-ray observations with eROSITA, Swift, NuSTAR and optical data from the optical Gravitational Lensing Experiment (OGLE) and the Las Cumbres Observatory (LCO), we confirm the nature of eRASSU J012422.9-724248 as a Be/X-ray binary (BeXRB) pulsar in the Magellanic bridge. The position is coincident with that of an early-type star (OGLE ID SMC732.10.7). We detect the spin period at 341.71 s in NuSTAR data and infer a period of 63.65 days from the 15 year monitoring with OGLE, that we interpret as the orbital period of the system. A tentative CRSF at ~12.3 keV is identified in NuSTAR spectra with ~1.8-sigma. The source appears to show a persistent X-ray luminosity and an optical magnitude transition on the long timescale. We propose eRASSU J012422.9-724248 is a new member of the class of persistent BeXRBs.

Growing evidence indicates that some fast radio bursts (FRBs) reside in dense, magneto-ionic environments where extrinsic propagation effects can substantially reshape the observed signal. Within a 1D Gaussian plasma-lens framework, we show that small, monotonic variations in the incidence angle of the FRB wavefront naturally generate both downward and upward sub-burst frequency drifts. We further demonstrate that distinct lensed paths that probe different rotation measures (RMs), can produce orthogonal polarization-angle (PA) jumps at gigahertz frequencies. In this picture, a $\sim 90^\circ$ PA transition requires only a modest RM contrast of order a few $\times10~\rm{rad~m^{-2}}$ between the multiple images. The chromatic activity of FRB 20180916B-earlier and narrower activity windows at higher frequencies-can be explained as preferential magnification near the outer caustic. Finally, the intrinsic resolution of a plasma lens provides an upper limit on the transverse emission size: lenses located close to the source yield magnetospheric-scale constraints and offer a practical means of discriminating between inner- and outer-magnetospheric emission scenarios. These results suggest that plasma lensing could account for multiple complex observational features of FRBs and may play a non-negligible role in modulating their observable properties.

The Lyman-alpha (Ly$α$) absorption profile in star-forming galaxies serves as a powerful tracer of the extended, dense neutral hydrogen in their surroundings during the Epoch of Reionization (EoR). We report a unique galaxy, A2744-z7DLA, at $z\approx 6.87$ gravitationally lensed by the foreground galaxy cluster Abell 2744, which exhibits both moderate Ly$α$ emission and damped Ly$α$ absorption, suggesting the presence of a dense neutral hydrogen environment. Our analysis suggests that the UV continuum turnover near Ly$α$ is more likely shaped by a damped Ly$α$ system rather than nebular continuum from two photon process. We analyze the physical properties of A2744-z7DLA with spectroscopic and photometric data from the JWST and the HST. The galaxy shows a compact morphology ($r_e \sim 0.3\ {\rm kpc}$) and a broadened H$α$ emission line, suggesting possible AGN activity. The broad component of H$α$ has a FWHM of $2721 \pm 200\ {\rm km\ s^{-1}}$, corresponding to a black hole mass of $M_{\rm BH}=2.90^{+2.35}_{-1.28}\times 10^7 M_\odot$ and a black hole-to-stellar mass ratio of $\log (M_{\rm BH}/M_{\rm stellar}) = -1.58^{+0.45}_{-0.34}$. The Balmer decrement ($\rm Hα/Hβ$) yields a dust attenuation of $\rm A_V \approx 1.15 \pm 0.23$, indicating that this system is less dust-rich than some "little red dots". Furthermore, we perform SED fitting using both stellar and AGN models. The results show that the UV and optical wavelengths are dominated by star-forming regions, while the AGN component contributes primarily at longer wavelengths. This work provides new insights into the interplay between star formation, neutral gas, and potential AGN activity in galaxies during the EoR.

Nearby galaxies exhibit a variety of structures, including central rings, similar to the MW Central Molecular Zone (CMZ). These rings are common in barred galaxies and can be gas-rich and highly star-forming. We aim to study molecular gas content and star formation rate of central rings within nearby galaxies and link them to global galaxy properties (e.g. bar morphology). We utilize $1\,$'' resolution CO(2-1) PHANGS-ALMA observations, visually identify 20 central rings and determine their properties. For $14$ rings, SFR surface density maps are available. We derive ring geometry, integrated molecular gas masses, SFRs, depletion times, and compare them to host galaxy and bar properties. Molecular gas is a good tracer for central rings: Previous studies used ionized gas and dust tracers to identify central rings in galaxies of similar morphological types as this study. In comparison, we find similar fractions of galaxies hosting central rings and similar radii distributions. The gaseous central rings have typical radii of $400_{-150}^{+250}\,$pc, molecular gas masses of $\log(M_\text{mol}/M_\odot){\sim}8.1_{-0.23}^{+0.17}$, and SFRs of $0.21_{-0.16}^{+0.15}\,M_\odot/\text{yr}$, thus contributing $5.6_{-2.1}^{+4.5}\,\%$ and $13_{-5}^{+10}\,\%$ to their host galaxies' molecular gas mass and SFR. The MW CMZ sits at the lower end of the radius, molecular gas mass, and SFR distribution, but it has a similar molecular gas mass and SFR fraction, and depletion time. Longer bars contain more massive molecular central rings, but we find no correlation between bar strength and the ring's molecular gas content. Although absolute central ring properties likely depend on host galaxy properties, the similarities between the MW CMZ and PHANGS central rings in relative parameters suggest that the processes of gas inflow and star formation are similar for central rings across nearby galaxies.

We present sub-arcsecond ($θ\sim0.1^{\prime\prime}$) resolution VLA 1.3 cm continuum and 22.2 GHz H$_2$O maser observations toward 15 compact radio continuum sources with rising spectral index and 8 string-like radio continuum structures in the Rosero et al. (2016, 2019) survey. Three different morphologies are observed: elongated or double-peak string-like structure (6 out of 23 cases), a collection of distinct continuum peaks (4 out of 23 cases), and single compact sources (13 out of 23 cases). The majority of H$_2$O maser spots detected are within a sky-projected distance of $\sim5,000$ au from the radio continuum peaks and tend to be well aligned and distributed in an elongated structure when more than three spots are observed. We generally recover less emission than Rosero et al. (2016, 2019), which together with the fact that more than half of the jet candidates in our survey appear mostly compact, suggest core/halo shock structures even on small scales. We also detected proper motion in 10 cases and measured an average projected velocity of approximately 120 km s$^{-1}$. Radio brightness variability is detected in at least two cases, possibly due to weak accretion bursts. This work, together with our previous molecular jet study, provides further evidence that support the main source of ionization in the studied sources is shocks, yet collimation is only observed in 4 cases. We conclude that the available data supports the thermal jet classification of 7 sources, and the ionized jet interpretation is further supported in 16 sources.

The cosmological principle assumes the isotropy of the Universe at large scales. It is a foundational assumption in the $Λ$CDM model, which is the current standard model of cosmology. Recent tensions give legitimacy to investigating the possibility of anisotropies in the Universe. The large sky coverage achieved by the Zwicky Transient Facility survey (ZTF) allows us to test the veracity of the cosmological principle using observations of Type Ia supernovae (SNe Ia). In this article, we develop a methodology to measure potential anisotropies in the Hubble constant $H_0$. We test our method on realistic simulations of the second data release (DR2) of ZTF SNe Ia in which we introduce a dipole. We develop an unbiased method both to introduce a dipole in the simulations and to recover it. We test a potential $H_0$ dependency of our method while varying the dipole amplitude. We analyse the impact of introducing large-scale structures in the simulations and the efficiency of using a volume-limited sample, which is an unbiased subsample of the ZTF SNe Ia sample. Finally, we build an error model applied to the recovered dipole amplitude ($ΔH_0$) and its direction ($α_0$, $δ_0$). Our analysis allows us to recover a dipole with an error on the amplitude of $0.33\,\mathrm{km\,s^{-1}\,Mpc^{-1}}$, and uncertainties of $3.4^\circ$ and $6.1^\circ$ on the right ascension and declination, respectively, for an initial dipole amplitude of $ΔH_0 = 3\,\mathrm{km\,s^{-1}\,Mpc^{-1}}$. The resulting dipole is independent of the chosen $H_0$ value and sky coverage. This paper paves the way for a future precise ZTF dipole investigation.

The formalism of Bayesian model selection provides a very elegant way of ranking different physical models in terms of how compatible they are with a given set of observed data. However, its practical application is often hampered by the challenge of having to compute the Bayesian evidence - a multi-dimensional integral over the product of likelihood and prior probability. This usually necessitates a large number of function calls to the likelihood, which may become prohibitive in case of "slow", costly to evaluate likelihoods. A possible solution to this problem lies in approximating the slow full likelihood by a fast emulated likelihood. In this paper, we introduce BOBE (Bayesian Optimisation for Bayesian Evidence), a method to construct a Gaussian Process Regression (GPR)-based emulator. BOBE utilises a Bayesian Optimisation algorithm designed specifically to (i) provide a realistic estimate of the emulator's uncertainty and its impact on the evidence calculation, and (ii) minimise the number of likelihood evaluations required in order to meet a given evidence accuracy goal. We apply it to a number of toy examples as well as actual cosmological likelihoods, and demonstrate that training the emulator to a sufficient accuracy takes a factor of $O(10^3)$ fewer direct likelihood evaluations than would be needed if one were to directly compute the evidence integral via nested sampling. BOBE's overhead is independent of the likelihood computation time $t_L$, making it particularly useful for "expensive" likelihoods with $t_L \gtrsim 1$~s. BOBE is written in Python, supports MPI parallelisation, takes advantage of automatic differentiation and just-in-time-compilation provided by JAX, can straightforwardly be implemented with cosmological data analysis frameworks such as Cobaya, and is available for download from https://github.com/Ameek94/BOBE.

We analyze the spectral energy distributions (SEDs), star formation histories (SFHs), and infrared-radio correlation (IRRC) of 221 850 $μ$m-selected submillimeter galaxies (SMGs) in the SSA22 deep field. The median mass-weighted age is 567 Myr. Most galaxies in our sample began forming $\sim$ 1.68 Gyr after the Big Bang, entered the 'SMG phase' after $\sim$ 1 Gyr of evolution -- when they are predominantly observed -- and largely transitioned out of the 'SMG phase' to become quiescent within an additional $\sim$ 0.2 Gyr. A subset of massive galaxies shows rapid early assembly with high star formation efficiencies ($\sim$0.2-0.8). The majority of SMGs reside at the high-mass end of the star-forming main sequence, with a characteristic stellar mass of $M_{star} \sim 10^{11}$ M$_\odot$, above which galaxies are predominantly either on the main sequence or already quenched. We observe a downsizing trend: more massive galaxies tend to ''mature" earlier, completing their major episodes of star formation at higher redshifts compared to lower-mass systems. Our sample contributes $\sim$ 21% (28%) to the cosmic star formation rate density (stellar mass density), including the overdensity, with its relative contribution peaking at 50-60% in the redshift range $z=2.5-3.5$. We suggest that 850 $μ$m surveys may miss a population of faint, warm galaxies at $z \geq 1$-2. The median infrared-radio correlation parameter $q_{IR}$ is 2.37, evolving as $(1+z)^{-0.11}$, likely due to AGN contributions at high redshift and intrinsic differences between low- and high-redshift populations.

We present a photometric analysis of 19 DA and 13 DAO white dwarfs (WDs) with effective temperatures exceeding 60 kK, building on the spectral analysis reported in the first paper of this two-part study. By examining archival light curves for periodic signals, we identify that four of the 32 objects ($13^{+8}_{-4}$%) exhibit photometric variability. Spectral energy distribution (SED) fitting allowed us to derive radii, luminosities, and gravity masses, as well as to characterise the infrared excesses observed in six sources. A notable discovery is the identification of a 1.87 d period in the ZTF light curves of WD1342+443 and weak emission lines in the optical spectra of this star, which strongly indicate an irradiation effect system. Our SED fit indicates the presence of cool dust, which must be located farther from the star, and that any companion with a spectral type earlier than L2.0 would appear in the SED. This leads us to speculate that WD1342+443 might have an irradiated, sub-stellar companion. We also highlight that we uncovered, for the first time, a 4.23 d photometric period in the well-known, close DA+dM binary WD0232+035, based on TESS data. We find that the phase and amplitude of the light curve variations are consistent with expectations from an irradiation effect. Intriguingly, we detected an additional, mysterious period at 1.39 d, which is approximately one-third of the orbital period. Moreover, we revisited the longstanding discrepancy between Kiel and gravity masses for the hottest WDs. To address this, we explored fully metal line blanketed model atmospheres as a potential solution, contrasting them with the results from pure H and H+He models. Our results show that including metal opacities does not resolve the discrepancy - in fact, it slightly deteriorates the agreement. Finally, we reaffirm the previously observed correlation between He abundance and luminosity.

The development of detectors using Silicon Photo-Multipliers for acquisition of fast light signals coming from Cherenkov and fluorescence emissions started by particle showers in the terrestrial atmosphere is the main goal of the Italian ASI/INFN Agreement n.2021-8-HH.2-2022, named "ASI/INFN_EUSO-SPB2", in view of the next generation of telescopes in balloon-borne and space-based experiments. A survey of performances of different Silicon Photo-Multipliers available on the market has been performed to identify the best sensors for space applications, where high thermal excursions and environmental radiation must be mainly taken into account in contrast to ground-based experiments. In particular, a characterization protocol for Silicon Photo-Multiplier qualification has been specified to Hamamatsu S13161-3050AE-08 sensor ($8 \times 8$) array in the $30 \, \textrm{C}^{\circ}$ down to $-40 \, \textrm{C}^{\circ}$ temperature range. The protocol specifies measurements of break-down voltage, quenching resistance, gain, dark count rate and the probability of cross-talk. These parameters have been measured as a function of temperature at fixed over-voltage. Based on these previous measurements, a dedicated set-up is under completion for performing massive tests to validate and calibrate 32 Silicon Photo-Multipliers (Hamamatsu S13361-3050 series, 64 channels each), composing the (2048 pixels, $12^{\circ} \times 6^{\circ}$ field of view) Focal Surface of the Cherenkov Camera that will fly on the POEMMA-Balloon with Radio mission. The technical details and description of this system and the procedural steps implemented are reported, preliminary measurements on the first Elementary Cell are also shown.

Little Red Dots (LRDs) are enigmatic, compact, red galaxies at high redshift, $z\sim 4$-$7$, discovered by the James Webb Space Telescope. Broad emission lines in the absence of X-ray and radio counterparts suggest that they host accreting supermassive black holes embedded in dense gaseous envelopes. This black-hole-envelope configuration facilitates efficient photohadronic interactions and neutrino production. Remarkably, their observed source number density and luminosity are compatible with the energetics of the diffuse neutrino background. We consider that relativistic jets and outflows are launched from the black hole and propagate through low-density polar funnels within envelopes, where particle acceleration and neutrino emission occur. This leads to LRDs being effectively hidden sources. Our analytic and numerical calculations show that, in an optimistic scenario, LRDs can contribute $\sim 30\%$ of the observed diffuse background at TeV$-$sub-PeV energies, predominantly through photomeson production. At high neutrino energies, $\gtrsim 10^{5.5}~{\rm GeV}$, inverse-Compton cooling of muons modifies the resulting flavor ratio, providing a distinctive diagnostic for IceCube-Gen2 and other upcoming neutrino telescopes.

We present a multiwavelength analysis of 850 $μ$m-selected SMGs (deblended S$_{\rm 850}\gtrsim$ 1mJy) in the SSA22 field, where our deepest JCMT/SCUBA-2 observations reach a sensitivity of $σ_{850}\sim$ 0.80mJy beam$^{-1}$. Using multiple identification methods, we have identified 248 deblended SMG candidates for 192 SCUBA-2 sources. The average multiplicity of SCUBA-2 sources is $\sim$26%, with brighter sources exhibiting higher multiplicity. After applying quality cuts based on SED fitting reliability, our final sample comprises 221 SMGs associated with 186 SCUBA-2 sources. The SSA22 SMGs have a median infrared luminosity of (2.25$\pm$0.25) $\times$10$^{12}$ L$_{\odot}$, with $\sim$ 63% ($\sim$ 8%) of the sample classified as ULIRGs (HLIRGs). The median redshift of the sample is $z = 2.00 \pm 0.08$, while optically faint galaxies exhibit higher median redshift ($\sim 2.20 \pm 0.17$). The comoving volume density of SMGs increases by a factor of $\sim 6$ at $z \lesssim 4$, plateauing at $\sim$ 1.78-3.16 $\times$ 10$^{-5}$ cMpc$^{-3}$ over $z \sim$ 1-3 (including the overdensity). The significant overdensity of SMGs within large-scale structures demonstrates their reliability as tracers of cosmic structure formation at high redshift. The median stellar mass and SFR of our SMG sample are $(1.55 \pm 0.22) \times 10^{11}$ M$_\odot$ and $166 \pm 25$ M$_\odot$ yr$^{-1}$, respectively. We observe a clear ''downsizing" signature: after cosmic noon ($z \lesssim 2$), massive SMGs exhaust their gas reservoirs and transition to quiescence, while lower-mass SMGs continue forming stars and dominate the cosmic SFR density. The sample has a median dust mass of (1.95 $\pm$ 0.14) $\times$ 10$^{9}$ M$_{\odot}$. The dust fraction ($ M_{\text{dust}}/M_{\text{star}}$) has a median value of (1.4 $\pm$ 0.2) $\times$ 10$^{-2}$. The median $A_V$ of SMGs is 3.09$\pm$0.07mag.

Dark matter dominates the matter content of the Universe, and its properties can be constrained through large-scale structure probes such as the cross-correlation between the unresolved gamma-ray background (UGRB) and weak gravitational lensing. We analysed 15 years of Fermi-LAT data, constructing UGRB intensity maps in ten energy bins (0.5-1000 GeV), and cross-correlated them with KiDS-Legacy shear in six tomographic bins. The measurements were performed using angular power spectra estimated with the pseudo-$C_\ell$ method. No significant cross-correlation is found. Based on this non-detection, we present 95% upper bounds on the weakly interacting massive particle (WIMP) decay rate $Γ_{\rm dec}$ and velocity-averaged annihilation cross-section $\langleσ_{\rm ann} v\rangle$ as functions of mass. We compare our results with bounds from other cosmological tracers and from local probes, and found them to be complementary, particularly at low masses ($\rm GeV/TeV$). In addition, using a Euclid-like lensing survey cross-correlated with Fermi-LAT, we forecast $\sim$2 times tighter limits, highlighting the potential of forthcoming data to strengthen constraints on dark matter annihilation and decay.

In recent years, intensity interferometry has seen renewed interest and successful application at Imaging Atmospheric Cherenkov Telescope arrays. These measurements are usually performed during bright moon periods while the instruments' primary purpose -- gamma-ray observations -- cannot be fulfilled. The Mobile Intensity Interferometer for Stellar Observations was designed as a proof of concept for a purpose-built intensity interferometer. Using acrylic Fresnel lenses 1 m in diameter with 1.2 m focal length, a compact, economical and lightweight design was realised. The detector fixture allows for translation in the z-axis to adjust for measurements at different wavelengths (and therefore focal points) and easy swapping of the detector in its entirety. Both mobility and scalability in quantity of this design allow for specific targeting of projected baselines and orientations based on the target. Particularly for potential binary systems, selective coverage of a target's u-v plane is essential to probing the characteristics accurately. A first campaign demonstrated the capability of these Fresnel lens telescopes by measuring the spatial coherence curve of Arcturus ($α$ Boo). In an observation time of less than 11 h, the angular diameter was measured with milliarcsecond precision, in agreement with the values in the literature.

The influences on the cluster number counts from the coupling between dark energy and dark matter with momentum transfer are investigated. We find that the extrapolated linear density contrast computed from the spherical collapse model is suppressed when the strength of momentum transfer is increased. Using the Sheth-Tormen mass function, the cluster number counts are computed. The minimum mass limit in the mass integration for each redshift bin is determined by matching the predicted number counts from the $Λ$CDM model with the result from eROSITA surveys. We find that the number of clusters is maximal at a higher redshift bin, and the number of clusters in a maximum redshift bin is enhanced when the strength of momentum and energy transfers increases due to the reduction of extrapolated linear density contrast. Setting the parameters of the dark energy model with momentum coupling according to the observational constraints in \cite{bestfit}, the predicted number counts from the coupled dark energy is larger than the result from eROSITA surveys. The statistical analysis yields a $p$-value of 0.189 for the proposed model relative to $Λ$CDM. Consequently, there is no statistically significant evidence of an improved fit over the standard $Λ$CDM framework based on the eROSITA cluster number counts.

Fast flavor conversions (FFCs) in supernovae, driven by neutrino-neutrino refraction, can catastrophically equilibrate flavors and potentially affect the neutrino-driven explosion. We present a pivotal insight: matter density fluctuations characterized by red spectra ($ν<0$), naturally arising in stratified supernova environments, can suppress such instabilities by inducing accelerated decoherence. By deriving exact analytical solutions for two-flavor evolution in red turbulent matter-where correlations grow as $t^{|ν|}$-we uncover a novel acceleration of coherence loss. This dynamical decoherence mechanism raises an effective energy barrier against the collective growth of flavor instabilities. Translating our master-equation results into an effective damping rate for FFC linear analysis, we find that realistic red turbulence ($ν\sim -1$, fluctuation strength $ξ_ν\sim 0.1$) can elevate the FFC threshold by a factor of $\sim 3-5$, potentially stabilizing regions that would otherwise undergo explosion-killing flavor equilibration (or vice versa). Our work provides the first analytical criterion for FFC suppression in turbulent media and identifies red turbulence as a critical, physics-grounded ingredient missing from current supernova models.

Cold Jupiters play a crucial role in planet formation and dynamical evolution. Since their initial discovery around 47 UMa, they have attracted significant interest, yet their formation mechanisms remain uncertain, underscoring the need to expand the known population. In this work, we combine RV data with Gaia astrometry using Hipparcos-Gaia proper-motion anomalies over a 25-year baseline. By jointly modeling both datasets with the MCMC framework, we constrain planetary masses, orbital inclinations, and three-dimensional orbital architectures. This reduces RV degeneracies and improves mass determinations. Four cold Jupiters are reported: HD 68475 b and HD 100508 b are each the first confirmed planet in their systems, with orbital periods $7832_{-323}^{+463}$ d and $5681\pm42$ d and dynamical masses of $5.16_{-0.47}^{+0.53} M_{\text{Jup}}$ and $1.2_{-0.18}^{+0.30} M_{\text{Jup}}$, respectively. In multi-planet systems, HD 48265 c has a period of $10418_{-1400}^{+2400}$ d and a mass of $3.71_{-0.43}^{+0.68} M_{\text{Jup}}$, while HD 114386 c orbits at $444.00_{-0.88}^{+0.93}$ d with a minimum mass of $0.37 \pm 0.03 M_{\text{Jup}}$. The two planets in the HD 48265 system may exhibit a significant mutual inclination, making it a target for testing the von-Zeipel-Kozai-Lidov mechanism. HD 68475 b is a promising candidate for future direct imaging with ELT/METIS. We identified a Jupiter analog with the longest known orbital period among planets with masses between 0.5 and 2 $M_{\text{Jup}}$, implying that a substantial population of cold Jupiters likely awaits discovery by Gaia. This study expands the sample of cold Jupiters with constrained orbits and dynamical masses, demonstrating the value of combining radial velocity and astrometry in exoplanet research.

Although the migration of hot Jupiters is not yet fully understood, measurements of the projected spin-orbit angle λ help shed light on the processes involved. Here we present Doppler tomography of three known hot Jupiters to determine their λ orientation: HAT-P-49 b, HAT-P-57A b, and XO-3A b. Our analysis explores the impact of cross-correlation processing methods on the detectability and characterization of the planet's Doppler shadow using up to three independent routines for cross-correlation functions extraction; those being: Yabi, iSpec and IRAF. After accounting for differences among the results obtained with the various routines, we report: first, the HAT-P-49 system is a case of a hot Jupiter on a polar orbit with λ=-85.3{\pm}1.7°, second, HAT-P-57A indicates practically no deviation of the planet's projected orbit from the host's equatorial plane with λ=-0.4^{+1.4}_{-1.9}°, and third, the XO-3A system with the measured value of λ=38{+3}_{-4}° lies in between an aligned and a perpendicular orientation, which is a less populated region of the spin-orbit distribution. Our findings highlight both the diversity of spin-orbit angles among close-in giant planets and the potential discrepancies in their measurement that can arise from different approaches to constructing the cross-correlation functions.

Extragalactic planetary nebulae (xPNe) in galaxies beyond the Local Universe serve as discrete tracers for studying the element abundances and kinematics of galaxies covering a wide range of morphologies and masses at a variety of angular distances, from the centre well out into their haloes. They are direct stellar probes to identify the galaxy progenitors of haloes and the intracluster light. Even with new facilities, reaching higher angular resolution and sensitivity, xPNe are the only stellar tracers that can be directly and singularly detected and characterised out to 100 Mpc distance, making them crucial for tracing halo and intracluster light assembly. New wide-field spectroscopic instruments at 10+meter-class telescopes will allow the unprecedented characterisation of xPN populations from galaxy centres to their diffuse outskirts. Panoramic integral-field spectroscopy will enable the simultaneous study of xPN and stellar population properties, establishing their use as age- and metallicity-tracers while also improving post-AGB stellar evolution models.

Previously we developed a local model for a spherically contracting/expanding gas cloud that can be used to study turbulence and small scale instabilities in such flows. In this work we generalise the super-comoving variables used in studies of cosmological structure formation to our local spherical flow model, which make it significantly easier to derive analytical solutions and analyse the interactions of more complex flows with the background. We show that a wide class of solutions to the local spherical flow model can be obtained via a mapping from the corresponding solutions in regular Cartesian flows. The rescaling of time in the transformation results in a modification of the linear instabilities that can occur in spherical flows, causing them to have a time dependent growth rate in the physical time coordinate, and can prevent slower instabilities from operating. Finally, we show that the small scale flows in isotropic contraction/expansion can be mapped directly to Cartesian, inviscid, incompressible hydrodynamics, meaning that one expects a form of rescaled Kolmogorov-turbulence at the small scale of isotropically contracting/expanding flows.

Under certain conditions, the oscillating inflaton condensate filling the Universe after inflation can fragment and form so-called oscillons. These long-lived soliton-like field configurations can dominate the Universe for several $e$-folds of expansion, leading to an early matter-dominated phase preceding the standard radiation era. In this paper we show how the rapid final decay of the oscillons leads to an enhanced production of induced gravitational waves, whose energy density can saturate the observational bound on the effective number of relativistic species. We leverage this bound to constrain the inflaton mass, cubic, and quartic self-coupling in generic models that admit oscillon formation, providing novel and complementary constraints in regions of parameter space that are inaccessible with cosmic microwave background observations alone.

Central flashes occur during stellar occultations by solar system objects. We catalog diffraction effects on the flash with point-like stars, monochromatic waves and spherical transparent atmosphere. Diffraction involves the Huygens principle, the Sommerfeld lemma and the stationary phase method, while finite stellar diameter cases involve Clausius' theorem. For point-like stars, the central flash shape is that of the classical Poisson spot, but with larger height. For tenuous atmospheres that cannot focus the stellar rays at shadow center, the flash is amplified by the factor (R_0/r_0)^2 compared to the Poisson spot, where R0 and r0 are the object and the shadow radii, respectively. For denser atmospheres that can focus the rays at shadow center, the flash peaks at 2[(pi*R/lambda_F})^2]*phi0, where R is the central flash layer radius, lambda_F is the Fresnel scale and phi0 is the flux that would be observed at shadow center without focusing. For isothermal atmospheres with scale height H, the height is 2(R*H)(pi/lambda_F)^2. Fringes surrounding the central flash are separated by lambda_P=lambda_F^2/R, related to the separation between the primary and secondary stellar images. For a projected stellar diameter D*>lambda_P, the flash is described by complete elliptic integrals, and has full width at half maximum of 1.14D* and peak value 8H/D*. For Earth-based occultations by Pluto and Triton observed in the visible with point-like stars, diffraction causes flashes with very large heights ~10e4-10e5, spread over a very small meter-sized region in the shadow plane. In practice, the flash is usually smoothed by the stellar diameter, but still reaches high values of ~50 and ~200 during Pluto and Triton occultations, respectively. Diffraction dominates when using millimeter wavelengths or longer. Effects of departure from sphericity, atmospheric waves and stellar limb darkening are discussed.

In the context of pre-processing -- a scenario in which galaxies quench their star formation within substructures before falling into clusters -- we investigate the impact of environment on the physical and morphological properties of galaxies in Compact Groups (CGs), focusing specifically on a sample of Star-Forming Compact Groups (SFCGs). Our aim is to characterize the physical and morphological properties of galaxies in SFCGs, analogues of the Blue Infalling Group, and to understand how the environment influences their evolution. We use photometric techniques to derive stellar masses and star formation rates (SFRs). Morphological parameters are extracted from DECaLS images, obtaining parametric properties such as the Sérsic index ($n$) and effective radius ($R_{\mathrm{e}}$) using GALFITM, as well as non-parametric indices -- including the Gini coefficient, $M_{20}$, and asymmetry -- from the same data. These indicators allow us to classify galaxies into E/S0/Sa, Sb/Sc/Ir, and merger types. All measurements are compared to a control sample of field galaxies to assess environmental effects. We find no significant differences in $n$ and $R_{\mathrm{e}}$ between SFCG and field galaxies, in contrast to results reported for other CG samples. However, SFCG galaxies exhibit higher specific star formation rates (sSFRs) than their field counterparts. Approximately $16\%$ of SFCG galaxies show merger features and elevated asymmetry. These mergers also present enhanced SFRs compared to both other SFCG types and the field population. We propose that SFCGs represent an earlier evolutionary phase of CGs, supported by their lower velocity dispersions and moderate crossing times, in addition to the observed SFR enhancement and the absence of pronounced morphological transformation. Galaxy mergers in this phase appear to enhance, rather than suppress, star formation.

We test whether a representation learned from interferometric strain transients in gravitational-wave observatories can act as a frozen morphology-sensitive operator for unseen sensors, provided the target signals preserve coherent elastic transient structure. Using a neural encoder trained exclusively on non-Gaussian instrumental glitches, we perform strict zero-shot anomaly analysis on rolling-element bearings without retraining, fine-tuning, or target-domain labels. On the IMS-NASA run-to-failure dataset, the operator yields a monotonic health index HI(t) = s0.99(t)/tau normalized to an early-life reference distribution, enabling fixed false-alarm monitoring at 1-q = 1e-3 with tau = Q0.999(P0). In discrete fault regimes (CWRU), it achieves strong window-level discrimination (AUC_win about 0.90) and file-level separability approaching unity (AUC_file about 0.99). Electrically dominated vibration signals (VSB) show weak, non-selective behavior, delineating a physical boundary for transfer. Under a matched IMS controlled-split protocol, a generic EfficientNet-B0 encoder pretrained on ImageNet collapses in the intermittent regime (Lambda_tail about 2), while the interferometric operator retains strong extreme-event selectivity (Lambda_tail about 860), indicating that the effect is not a generic property of CNN features. Controlled morphology-destruction transformations selectively degrade performance despite per-window normalization, consistent with sensitivity to coherent time-frequency organization rather than marginal amplitude statistics.

We apply the angular two-point correlation function (TPCF) to the spatial distribution of young star clusters (YSCs) in four nearby star forming galaxies (NGC 628, NGC 4449, M51, and M83) in order to investigate their underlying hierarchical structuring. Using newly constructed catalogs of YSCs in the emerging phase (eYSCs), identified in the infrared with JWST, and optical YSCs detected in archival HST data, we compute TPCFs for various cluster samples and age bins across the four galaxies as part of the FEAST (Feedback in Emerging extrAgalactic Star ClusTers) program. We find clear evidence of hierarchical structuring, especially in eYSCs and YSCs with ages < 10 Myr (referred to as oYSCs), which show similar TPCFs within each galaxy. NGC 628 exhibits a clear distinction between the TPCFs of eYSCs and oYSCs, implying a shorter randomization timescale. In contrast, clusters aged 10 to 300 Myr exhibit progressively more random spatial distributions, becoming effectively random after $\sim$ 100 Myr, consistent with earlier studies. The two-dimensional fractal index $D_2$ of the YSCs underlying distribution is calculated from model fits to TPCFs. Our values of $D_2$ derived from the youngest YSC populations align better with the expected value of $D_2 \sim $1.3 for a universal star formation process compared to previous findings.

We have used Auriga -- a set of state-of-the-art cosmological hydrodynamical simulations of Milky Way-size systems -- to study the impact of baryons on the Galactic subhalo population. A DM-only run counterpart of Auriga allows us to compare results with and without baryons. We repopulate the original suites with low-mass subhalos orders of magnitude lighter than the mass resolution limit, starting from a detailed characterization of Auriga data in the well-resolved subhalo mass range. The survival of low-mass subhalos to tidal forces is unclear and under debate nowadays, thus in our study we stay agnostic and consider two different levels of subhalo resilience to tidal stripping ('fragile' and 'resilient' subhalos). We find baryons to alter the Galactic substructure significantly, by decreasing its overall abundance by a factor $\sim2.4$ (fragile) and $\sim1.9$ (resilient) and subhalo concentration -- here defined in terms of maximum circular velocity -- by $\sim1.5$ with respect to the DM-only scenario. This has important consequences for indirect searches of DM. As an example, we investigated the case of using unidentified gamma-ray sources to set constraints on the DM particle properties, assuming some of them may be dark satellites. We find the DM annihilation cross-section constraints to worsen by a factor $\sim3.6$ in the most realistic scenario of including baryons, compared to DM-only simulations in the 'fragile' setup. Yet, a stronger resilience of subhalos to tidal stripping improves these DM limits by a factor $\sim4.5$ and $\sim10$ compared to the DM-only and hydrodynamical 'fragile' cases, respectively. Our results show the importance of including baryons to properly characterize the Galactic subhalo population, as well as to propose the most optimal subhalo search strategies, not only via its potential DM annihilation products but also through their gravitational signatures.

Mini-EUSO is the first space-borne detector of the JEM-EUSO (Joint Exploratory Missions for Extreme Universe Space Observatory) program, operating on the International Space Station (ISS) since October 2019. Designed to search for Ultra-High Energy Cosmic Rays (UHECRs) above 10$^{21}~$eV and capable of placing a stringent upper limit on their flux at these extreme energies, paving the way to future space-based UHECR observatories, Mini-EUSO has completed more than 150 observation sessions over five years, accumulating approximately 750 hours of data. The mission has produced the first global UV emission maps of Earth and provided valuable insights into lightning phenomena and Transient Luminous Events (TLEs), such as elves, as well as artificial light sources and meteors. Notably, Mini-EUSO has conducted the first systematic space-based meteor survey, detecting over 22,000 meteors and identifying three interstellar candidates. Among the observed TLEs, the most interesting class of phenomena are elves, which appear as expanding ring-shaped structures occurring at $\sim$90 km altitude. Mini-EUSO has detected elves with varying structures and different numbers of concentric rings, from single-ring up to five rings. Thanks to its imaging capabilities, fast time resolution, and favorable observational geometry, Mini-EUSO is uniquely suited to studying this kind of lightning phenomena, providing unprecedented insight into their dynamics. Additionally, the instrument has demonstrated the capability of a space-based detector to identify short light transients resembling extensive air shower signals while distinguishing them from those produced by UHECRs. This contribution presents a comprehensive summary of the Mini-EUSO mission, its status, and main results.

We present a study of Pseudo-LRD-NOM (Pseudo little red dot with no metal lines), a highly magnified low-mass galaxy behind the lensing cluster Abell 370 at z=5.96. We classify this object as a pseudo-LRD because its red rest-frame optical colour is mainly driven by a prominent Halpha line (with EW0 >~ 800 Angstroms) present in its JWST NIRSpec spectrum. Halpha is dominated by a narrow component and also has a minor broad component indicative of an active black hole with M_BH = 2.9x10^6 Msun. A narrow Hbeta emission line is also detected (with S/N = 8), producing a Balmer decrement (narrow) Halpha/Hbeta = 11. The rest-frame UV spectral slope is beta_UVspec = -1.2. All these features can be ascribed to high dust attenuation. However, no [OIII]5007 or any other metal lines are detected in the spectrum, so [OIII]5007/Hbeta < 0.25, at odds with a simple dust-attenuation explanation. Accounting for all the spectral properties requires the model of a starburst with moderate colour excess E(B-V)=0.18-0.45, high gas density (n_H >~ 10^6 cm^{-3}) and extremely low gas/stellar metallicities (Z = 0.01-0.1 Zsun). The demagnified stellar mass is 1.62^{+1.54}_{-0.79} x10^7 Msun and the stellar-mass surface density is Sigma* = 418^{+725}_{-310} Msun/pc^2, similar to that of massive/nuclear star clusters. Pseudo-LRD-NOM provides evidence of massive black-hole growth occurring in a high-density, dusty starburst which is at the early stages of its chemical enrichment, and is likely a precursor to a real LRD.

We present observations and analysis of the bound planetary microlensing event KMT-2025-BLG-1616. The planetary signal was captured by the Korea Microlensing Telescope Network (KMTNet) and the DECam Rogue Earths and Mars Survey (DREAMS). DREAMS's minute-cadence observations break the central/resonant degeneracy in the binary-lens models. The color of the faint source star ($I=22$) is measured from the DREAMS's $r - z$ color. The planetary system has a planet-host mass ratio of $q \sim 5 \times 10^{-4}$. A Bayesian analysis yields a host-star mass of $\sim 0.3\,M_\odot$, a planetary mass of $\sim 40\,M_{\oplus}$, a projected planet-host separation of $\sim 1.6~\mathrm{au}$, and a lens distance of $\sim 7.5~\mathrm{kpc}$. Based on the photometric precision achieved by DREAMS for this event, we simulate free-floating planet (FFP) detections and find that DREAMS is sensitive to Mars-mass FFPs in the Galactic bulge and Moon-mass FFPs in the Galactic disk.

The peak luminosities and rates of decline for a large sample of novae recently published by Clark et al. have been analyzed using the Yaron et al. nova models to estimate fundamental properties of the M31 nova population. The apparent white dwarf (WD) mass distribution is approximately Gaussian with a mean $\langle M_\mathrm{WD} \rangle = 1.16\pm0.14~M_{\odot}$. When corrected for recurrence-time bias, the mean drops to $\langle M_\mathrm{WD} \rangle = 1.07~M_\odot$. The average WD mass of the M31 nova sample is found to be remarkably similar to that found by Shara et al. in their study of 82 Galactic novae, but $\sim0.15~M_\odot$ more massive than the mean recently determined by Schaefer in his comprehensive study of more than 300 systems. As expected, the average WD mass for the recurrent novae included in the M31 sample, $\langle M_\mathrm{WD} \rangle = 1.33\pm0.08~M_{\odot}$, is significantly higher than that for novae generally. Other parameters of interest, such as the accretion rate, velocity of the ejecta, and the predicted recurrence time, are characterized by skewed distributions with large spreads about means of $\langle \log \dot M ~(M_\odot~\mathrm{yr}^{-1}) \rangle \simeq -9.27$, $\langle V_\mathrm{max} \rangle \simeq 1690~\mathrm{km~s}^{-1}$, and $\langle \log P_\mathrm{rec}~\mathrm{(yr)} \rangle \simeq 4.39$, respectively. The role of hibernation in affecting the $\dot M$ and $P_\mathrm{rec}$ distributions is briefly discussed. Finally, the nova properties were studied as a function of apparent position (isophotal radius) in M31, with the preponderance of evidence failing to establish any clear dependence on stellar population.

Recently, the experimental realization of a Kapitza potential in a Bose-Einstein Condensate (BEC) has been reported for the first time in literature, motivating further theoretical investigations of such system. At the same time, in the astrophysical context, BEC dark matter models have been widely studied as a possible phenomenological explanation for the dark matter phenomena. We model the galactic structure with an inner cored profile obtained from the ground state equilibrium solution of the Schroedinger-Poisson together with a Kapitza-BEC like interaction for the tail region. We find reasonable agreement of the model with representative galaxy rotation curves available in the SPARC catalogue.

In radio interferometric observations, the main source of information is the complex visibility function, which includes amplitude and phase. In this paper, the dependence of the phase of the visibility function on the base projection is investigated when used in radio interferometry with space bases up to six Earth diameters. The dependence of the phase of the visibility function on the projection of the base and direction is obtained. It is shown that for small values of the base projections, this dependence has a universal character and is consistent with the results of numerical magnetohydrodynamic models.

We present JWST/NIRSpec PRISM observations of a robust galaxy candidate at $z\simeq14$, selected from pure-parallel NIRCam imaging; PAN-z14-1. The NIRSpec spectrum allows confirmation of this source at $z_{\rm spec}=13.53^{+0.05}_{-0.06}$ through modeling of the Lyman-$α$ break. PAN-z14-1 is the fourth most distant galaxy known to date and is extremely luminous ($M_{\rm UV}=-20.6\pm0.2$), with a blue UV-continuum slope ($β=-2.26\pm0.08$) and a large physical size ($r_{\rm c}=233\pm10\, \rm pc$). We fail to detect any rest-frame UV emission lines at $\geq 2σ$ significance, with upper limits sufficiently constraining to exclude the possibility of strong line emission. In terms of its physical properties, PAN-z14-1 is remarkably similar to the previously confirmed $z_{\rm spec}=14.18$ galaxy GS-z14-0. The lack of strong emission lines and large physical size is consistent with an emerging picture of two potentially distinct galaxy populations at $z>10$, distinguished by star-formation rate surface density. In this scenario, PAN-z14-1 is a second example of a ''normal'', extended, luminous, star-forming galaxy at $z \simeq 14$, and differs markedly from the other class of extremely compact galaxies with strong emission lines recently uncovered at extreme redshifts with JWST. These results highlight the importance of further spectroscopic confirmation of $z>10$ galaxy candidates in order to fully understand the diversity of properties displayed by the first galaxies.

The intrabinary shocks (IBS) in spider pulsars emit non-thermal synchrotron X-rays from accelerated electrons and positrons in the shocked pulsar wind, likely energized by magnetic reconnection. The double-peaked X-ray light curves from these shocks have been well characterized in several spider systems. In this paper, we analyze Imaging X-ray Polarimetry Explorer (IXPE) observations of the redback pulsar J1723$-$2837 to examine the expected synchrotron polarization. Using advanced extraction methods that include spatial, temporal, and particle background weights, we constrain the polarization of the IBS. We compare different models for the magnetic field in the radiation zone and find that the best fit prefers a striped pulsar wind model over other polarized models, with maximum polarization degree of the IBS emission component $Π_{\rm IBS}=36^{+16}_{-15}\%$, in addition to an unpolarized non-IBS component. Since this is only 2.4$σ$, we cannot claim strong preference over an unpolarized model; we report a $99\%$ confidence level upper limit on the total polarization of both IBS and non-IBS components $Π_{99}<36\%$, which is improved over the $50\%$ limit obtained in previous work. The best-fit polarization of the IBS component is consistent with numerical simulations. Detailed tests of such models are accessible to future measurements.