In a recent paper, arXiv:2509.19899, we presented a new method to test the consistency between uncalibrated BAO and SNIa data through a common parameter, the Alcock-Paczynski variable. Using Gaussian Processes, we can determine if various datasets are consistent, independently of dark energy or modified gravity models, and of the sound horizon and SNIa peak magnitude. We found that the DES-Y5 SNIa data showed non-negligible tension with other datasets. However, the recent update DES-Dovekie removes this tension. We find that all uncalibrated data from DESI DR2 BAO and three SNIa datasets, Union3, Pantheon+, and DES-Dovekie, are consistent with each other within $\sim 1\sigma$.

The near geometrical progressions of distances of main regular secondaries in the planetary system and in the satellite systems of Jupiter, Saturn and Uranus are often disregarded, contrary to other regular orbital features. Among dynamical effects other than direct gravitational interactions, primary tides and gas drag cause the secondary's semi-major axis to evolve secularly. The consequences of these two effects on the mean ratios of secondary orbital distances are assessed for the four systems. A general relation is first derived to estimate a past initial mean distance ratio and is characterised for primary tides and for the drag caused by primordial nebulae. Results show first that the mean distance ratios of the four systems did not evolve sensibly under primary tidal action for periods corresponding to the age of the Solar System, and that the mean distance ratios are approximately conserved after the dissipation of initial nebulae. Secondly, the mean distance ratios may not have changed much due to gas drag caused by primaeval nebulae after formation of initial proto-secondaries and for periods corresponding to assumed lifetimes of nebulae, depending on initial nebulae models and on periods of effective drag. These results involve only the systems' mean distance ratios and do not imply that neither the secondary distances nor the individual distance ratios are conserved. Resonances among secondaries mean motions would reinforce the approximate conservation of mean distance ratios.

In the Gaia era, a comprehensive analysis of the binary open clusters NGC 869 (h Persei) and NGC 884 (chi Persei) system has been conducted to investigate its structural, astrophysical, kinematic, and Galactic orbital properties, along with its dynamical evolution. By applying the UPMASK algorithm to Gaia astrometric data for the estimation of cluster membership probabilities, it has been determined that 808 stars in NGC 869 and 707 stars in NGC 884 exhibit the highest statistical likelihood of being cluster members. The fundamental astrophysical parameters of the clusters were inferred within a Bayesian framework using Gaia data and PARSEC stellar evolutionary isochrones, through the application of the Markov Chain Monte Carlo (MCMC) technique. The estimated parameters are: colour excess E(B-V) = 0.516 +0.17/-0.24 mag and 0.516 +0.22/-0.33 mag, distances 2376 +301/-278 and 2273 +230/-290 pc, ages log(t/yr) = 7.31 +0.17/-0.32 and log(t/yr) = 7.30 +0.13/-0.29, and metallicities [Fe/H] = -0.24 +/- 0.12 and [Fe/H] = -0.25 +/- 0.12 dex for NGC 869 and NGC 884, respectively. Since spectroscopic observations are not available for the clusters, SED analysis was employed for the member stars, yielding results consistent with those obtained using the MCMC method. Kinematic and Galactic orbital analyses suggest that the open clusters originated in nearby regions of the Galaxy. This interpretation is supported by their similar space velocities and Galactic orbital parameters. Furthermore, orbital integration over 1 Gyr indicates a potential interaction between the clusters within the next 11 Myr. This study provides strong evidence of a common origin and a possible future dynamical interaction, contributing valuable insights into the formation and evolution of binary open clusters in the Milky Way.

This letter reports statistically significant changes in the equivalent widths of MgII and CaII lines in the dusty and polluted white dwarf WD 0106-328, based on six epochs of spectroscopy using the VLT and Keck spanning 25 yr. Furthermore, the ratio of these two equivalent widths may also vary, with a 7% probability of being constant. Between 2000 and 2025, both Mg and Ca have experienced decreases in accretion rates, of approximately 20 and 60%, respectively, but with individual variation during the interim. These metal abundance decreases are the first empirical corroboration of diffusion theory in white dwarfs, which predict sinking timescales on the order of days for this star. However, the persistent atmospheric metals require a more gradual, circumstellar process, where one possibility is viscous spreading in an ionized disk of metals, consistent with $\alpha\approx0.1$ within that formalism. The combination of optical and ultraviolet spectroscopy with the Hubble Space Telescope detects all the major rock-forming elements (O, Mg, Si, Fe), and demonstrates that Fe dominates the accreted material by mass, and that it is delivered mostly as pure metal from within a differentiated parent body. This inference is consistent with the possibility that chemically-segregated accretion may result from a combination of planetary assembly, fragmentation, disk evolution, and be observed on relatively short timescales.

Asteroid impactors larger than ~10 m, from Chelyabinsk-scale airburst and Tunguska-scale events to >300 m continental threats, remain the dominant planetary-defense risk. While the Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST) will transform Solar System science, its observing cadence and survey design were not specifically optimized to discover imminent impactors. To assess its performance, we introduce a new method for efficiently generating synthetic impactor populations by minimally perturbing sampled NEOMOD3 orbits and evaluate their discovery efficiency with the Sorcha survey simulator. Our simulations show that LSST discovers 79.7% of large impactors (>140 m), decreasing to 50.3% for upper mid-sized (50-140 m), 26.8% for lower mid-sized (20 - 50 m), and 10.5% for small objects (10-20 m). Warning times of the discovered impactors show a similar size dependence: small objects are typically discovered only weeks before impact (median:12.4 days), lower mid-sized within a month (median: 21.5 days), and upper mid-sized objects on timescales of a few months (median: 106.2 days). 39.0% of large impactors are discovered more than a year before impact, lacking long-lead warning despite their brightness. A loss-mode analysis reveals the underlying cause that small impactors are limited mainly by photometric sensitivity, whereas mid-sized and large objects are missed primarily due to cadence and linking constraints from LSST and its Solar System Processing (SSP) Pipelines. These results show that LSST excels at discovering faint, small impactors, but cannot by itself guarantee long-lead warning across the hazardous size spectrum. Coordinated multi-survey strategies will therefore be essential in the LSST era to achieve robust planetary-defense capability, and we study a complementary high-cadence, shallow-depth example with the Argus Array.

Obtaining a census of dark matter structures at low mass ($\leq 10^9 M_\odot$) can provide strong constraints on the nature of dark matter, though identifying such structures remains difficult. In this work, we study the galaxy cluster RX J0437.1+0043, taking advantage of its powerful "exotic" Hyperbolic-Umbilic (HU) lensing configuration to search for substructure candidates. Using a combination of high resolution imaging, IFU spectroscopy, and gravitational lensing modelling, we report on a tentative detection of a dark matter subhalo ($m_{\rm halo} = 2.25 \pm 0.94 \times 10^9 M_\odot$) near the vicinity of one of the largest HU images. We stress that this result is still preliminary and that deeper data and more advanced modelling techniques are needed to ultimately confirm this detection. Nevertheless, this work outlines the first steps towards understanding subhalo properties in dense cluster environments, developing HU cluster lenses as a potential new tool for investigating dark matter.

Tomographic reconstruction of reionization is a long-sought goal. It would move the field beyond global summary statistics, such as the volume-averaged ionised fraction, to direct, field-level constraints on the ionization topology. With this in mind, we present TORRCH (TOmographic Reconstruction of the Reionization of Cosmic Hydrogen), a deep-learning framework that reconstructs the neutral-hydrogen fraction field during the epoch of reionization from the spatial distributions of Ly$\alpha$ emitters (LAEs) and non-Ly$\alpha$-selected galaxies (NLSGs) at luminosity limits comparable to current surveys. Using hydrodynamical simulations post-processed with radiative transfer, we train a deterministic 3D U-Net on mock surveys spanning diverse reionization scenarios and predict the neutral-fraction field. We find that TORRCH recovers the large-scale ionization morphology from synthetic data comparable to current surveys with high fidelity, and reproduces both the one-point distribution and the 2D power spectrum of projected neutral fractions. The predicted galaxy-IGM cross-correlation is also captured well, including the expected small-scale anti-correlation and its decline towards zero at large separations. Reconstruction quality depends on tracer completeness, with deep joint LAE+NLSG samples yielding the most accurate morphology, while LAE-only selections retain bubble-scale topology but with reduced fidelity. Robustness tests show that the method is stable to variations in ionization conditions between training and test data, and to realistic redshift uncertainties. Our results suggest that galaxy-based tomography can potentially deliver reliable reionization maps across realistic survey redshift windows.

We present a binary-based reassessment of the age of the intermediate-age open cluster NGC 7789, together with well-constrained stellar parameters for twelve components in six SB2 systems, including two eclipsing binaries. Our analysis employs a unified modelling framework that combines radial-velocity orbits, TESS light curves, and blue-to-IR spectral energy distributions (SEDs), providing a robust alternative to traditional isochrone-based age determinations. By adopting common cluster-wide parameters (age, distance, and line-of-sight extinction) when solving for the stellar parameters of the binary components, we obtain a coherent set of masses, radii, effective temperatures, and luminosities for all twelve stars. The combined SED, eclipsing-binary, and radial-velocity analysis yields a well-constrained cluster age of $1.26 \pm 0.09$ Gyr and an extinction of $A_V = 0.90 \pm 0.05$ mag, while remaining consistent with the Gaia DR3 distance of $d \simeq 2.06$ kpc used as an external prior. An independent Gaia DR3 astrometric analysis gives a distance of $2082 \pm 142$ pc and confirms the membership of all six systems. The twelve binary components occupy the turnoff and subgiant regions of the cluster, enabling stringent evolutionary tests: in the radius--mass, radius--temperature, and temperature--mass diagrams, they show excellent agreement with modern stellar evolution models for the derived cluster parameters. NGC 7789 thus serves as a valuable benchmark for multi-observable, binary-based age determinations in open cluster studies.

The Event Horizon Telescope (EHT) Collaboration produced the first image of the apparent shadow of the central black hole of Sagittarius\,A$^*$ (\sgra). \sgra source structure varies significantly on timescales shorter than the duration of an observation, preventing improved data coverage through Earth rotation aperture synthesis. This rapid variability provides the opportunity to quantify intrinsic variability and separate time-variable emission features from stable signatures of strong gravity and the accretion environment. To infer the properties \sgra and its surrounding accretion flow, we perform Bayesian inference on a series of EHT data segments (``snapshots''). We directly fit parameters of a semi-analytic emission model jointly with complex station gains to snapshot visibilities, then extract estimates of the time-averaged, persistent source structure and temporal variability by stacking snapshots in a Bayesian hierarchical model. This approach successfully reproduces parameters of General Relativistic Magnetohydrodynamics simulations using synthetic EHT observations. Even with physically motivated assumptions about the \sgra environment, black hole spin and magnetic field parameters are poorly constrained by 2017 EHT observations. Our inference constrains other parameters, favoring a nearly face-on observer inclination ($\theta_{\rm o} = 9.2\degree \pm 3.6 \degree \pm_{\rm v} 11.6\degree$), an emission peak near the horizon ($R_{\rm peak} = 4.9 \pm 0.1 \pm_{\rm v} 0.5\,GM/c^2$), near-vertical projected spin position angle ($p.a. = 7.3\degree \pm 7.08 \degree \pm_{\rm v} 43.5\degree$ counterclockwise from vertical), and dominant emission $43.4\degree \pm 2.0\degree \pm_{\rm v} 5.9\degree$ above the equatorial plane, where we separate average structure uncertainty ($\pm$) from the impacts of temporal variability and model misspecification ($\pm_{\rm v}$).

proto-Lightspeed is a new instrument that has been commissioned on the Nasmyth East port of the Magellan Clay Telescope at Las Campanas Observatory to deliver high-speed optical imaging with deep sub-electron read noise. Making use of commercial re-imaging lenses and the ORCA-Quest 2 camera from Hamamatsu, proto-Lightspeed images a field $1'$ in diameter at up to $200$ Hz or windowed fields at higher rates, up to 6600 Hz for a $1.6''\times 1'$ field of view. proto-Lightspeed delivers seeing-limited image quality in the $g'$, $r'$, and $i'$ bands and adjustable magnification for pixel scales between $0.017''-0.050''$. proto-Lightspeed is well suited to studying compact binary systems, exoplanet transits, rapid flaring associated with accretion, periodic optical emission from pulsars, occultations of background stars by small trans-Neptunian Objects, and any other rapidly variable source. proto-Lightspeed will be a P.I. instrument beginning in 2026B, available for use by members of the Magellan Consortium. In this paper, we discuss the design and performance of the instrument, results from its two commissioning runs, and plans for a facility instrument, Lightspeed, to support simultaneous multicolor imaging across a $7'\times4'$ field.

We present constraints on the sum of neutrino masses $\sum m_\nu$ from a dataset incorporating the full SPT-3G 2018 TT/TE/EE+lensing spectra together with Planck PR4 lensing and low-$\ell$ parts of the Planck PR3 spectra. Using it as a baseline for the DESI DR2 BAO measurements, we arrive at a $95\%$ upper limit of $\sum m_\nu < 0.11$ eV, relaxing the tension between $\rm \Lambda$CDM and lower bounds on $\sum m_\nu$ based on neutrino oscillation experiments. When including DES Y1 weak lensing information and the Pantheon+ SNIa catalog, the limit is further loosened to $\sum m_\nu<0.138$ eV with a slight preference for $\sum m_\nu>0$. On contrast, replacing SPT-3G 2018 primary CMB and lensing spectra with ones from the SPT-3G 2019-2020 (D1) release tightens the overall constraint to $<0.082$ eV and pushes the $\sum m_\nu$ posterior mode value to zero, indicating a preference for quasi-negative neutrino masses in line with the D1 analysis. This is a curious shift within SPT-3G measurements of the same field taken in 2018 and in 2019-2020 and processed with different analysis pipelines.

We present the first sample of 222 high-redshift (z>0.5) star clusters, detected with JWST/NIRCam in 78 magnified galaxies from different galaxy cluster fields. The majority of the systems (~60%) is observed in the very deep NIRCam observations of the cluster AbellS1063 (GLIMPSE program), showing the power that deep observations, combined with lensing, has to reveal these primordial stellar structures. We perform simultaneous size-flux estimates in all available NIRCam filters and spectral energy distribution (SED) fitting analysis to recover star cluster physical properties. All star cluster candidates have very high magnification. Star clusters and clumps show similar ages and redshift distributions, although noticeable differences are seen in their masses, sizes and stellar surface densities inherent to the lack of resolution in the latter group. We reconstruct the formation redshift of star clusters and find that the large majority of the observed star clusters show young ages (<100 Myr) and seems to form at cosmic noon (CN,1<z<4). A small sample of CN star clusters is about 1 Gyr old, these potential globular clusters have formed well within cosmic reionization. Star clusters have stellar densities in the range 10^2 to 10^6 M/pc^2, with median values around 10^4 pc2. Their sizes and densities better overlap with those of nuclear star clusters in the local Universe. These intrinsic properties make high-z star clusters a viable channel to grow intermediate mass black holes. We use Bayesian inference to make first direct measurement of the star cluster mass function at z>1, based on a subsample of 60 star clusters younger than 100 Myr and with masses above 2e6 Msun. The star cluster mass function is well described by a power-law with slope beta = -1.89 suggesting that a power-law -2 function might already be in place in the distant Universe.

Star formation timescales are key to understanding fundamental physics like feedback mechanisms, as well as the abundance of bright galaxies at $z>10$. We investigate galaxy star formation histories (SFHs) and their evolution across $z\sim3$--9 by measuring the line-to-UV ratio (\rline) and line equivalent width (EW) of \hanii\ and \oiiihb\ directly from UNCOVER/MegaScience spectro-photometry without relying on a specific SFH or nebular line modeling. Our photometric measurements recover \rline\ and EW to $<10\%$ systematic accuracy compared to spectroscopy. This allows us to construct a large mass- (and flux-) complete sample and quantitatively examine how \rline\ evolves with redshift and stellar mass. We find that the intrinsic scatter in \rline\ does not significantly evolve with redshift across $3<z<7$, though it may increase at $z\gtrsim8$. We build population-level toy models using \texttt{fsps} to help interpret our observations, and find that scatter in \rline\ primarily reflects the amplitude of SFH fluctuations; this implies that our observed lack of evolution in the scatter of \rline\ is due to similar star formation burstiness from $z\sim3$ to $z\sim7$. Our observations are best reproduced by a set of SFHs with rising, long-duration, and large-amplitude bursts. Finally, we demonstrate that the toy model that best describes our $z\sim6$ data can boost UV brightness by up to $\Delta M_{\rm UV}\sim-2.0\,{\rm mag}$ compared with a 200\,Myr constant SFH, and naturally produces a large number of galaxies at $z>10$. This suggests that no significant evolution in star formation burstiness is required to explain the abundance of UV-bright galaxies at high redshift.

Giant radio haloes are diffuse synchrotron sources typically found in merging galaxy clusters, while smaller mini-haloes occur in cool-core clusters. Both trace cosmic-ray electrons in the intracluster medium, though recent observations suggest their distinction is not always clear. We present new 903-1655 MHz MeerKAT observations of Abell 1775 and Abell 1795, both hosting cool cores and cold fronts. Combined with reprocessed 120-168 MHz LOFAR Two-metre Sky Survey data, we perform imaging and spectral analyses of their radio emission. In both clusters, we detect radio haloes with distinct inner and outer components. In Abell 1775, the halo appears diffuse at 1.3 GHz, while LOFAR images reveal steep-spectrum filaments. In Abell 1795, the inner component corresponds to a previously reported mini-halo candidate, but the full structure extends to $\sim$1 Mpc with a spectral index of $\alpha=-1.08\pm0.06$. The presence of such a large, flat-spectrum halo in a dynamically relaxed cluster makes Abell 1795 an outlier relative to typical merging systems. This suggests that some relaxed clusters may still retain sufficient turbulence to sustain particle re-acceleration, or that hadronic interactions producing secondary electrons play a significant role. Together with other recent discoveries in cool-core systems, our results indicate that some large radio haloes may have been overlooked in past studies due to limited dynamic range near bright central AGN. Finally, we detect steep-spectrum emission south of Abell 1795's central AGN, tracing a 45 kpc X-ray and optical filament that terminates in an X-ray cavity, likely linked to a past AGN outburst.

We develop a geometry-first model that maps measured thin-disk water megamaser observables--sky angles, frequency shifts, their secular drifts and the angular redshift rate--to the black hole parameters in a generic static, spherically symmetric (SSS) spacetime written in the Schwarzschild gauge. The core of the approach is local: dot-product relations in the equatorial curved geometry relate the conserved light-deflection parameter to the observed detector angle at finite distance, providing a connection between sky positions and photon constants of motion. These local identities feed a closed model for the frequency shift of photons traveling between a maser clump circularly orbiting a black hole and a finite-distance detector, making explicit the dependence on the metric at emission and detection radii. We also apply the Gauss-Bonnet theorem to this construction on the equatorial two-manifold as an intrinsic cross-check. This theorem provides a global consistency relation between the local emission and detection angles, helping to validate sign conventions and angle branch choices in the local setup. In this sense, the local and global perspectives on the megamaser system support each other. To supplement the instantaneous information contained in frequency shifts, we incorporate the time-domain general relativistic invariant, the redshift rapidity. We further introduce a prospective angular-domain observable, the angular redshift rate, and give its analytic expression in the SSS framework. The results are formulated for generic SSS backgrounds, providing closed relations suited for likelihood-based inference from VLBI positions and spectral monitoring. In particular, for a Schwarzschild background, the black hole mass, its distance to Earth and megamaser orbital radius are fully constrained in the language of astrophysical observables.

Modern surveys such as Euclid report a decline in the fraction of barred galaxies from the local Universe to $z \sim 1$, whereas the TNG50 simulation predicts higher bar fractions, in tension with observations. This discrepancy may be due to observational biases in bar detectability when comparing simulations with observations. We present a proof-of-concept study quantifying how Euclid-like observational conditions affect bar detectability in TNG50. We analysed the entire galaxy sample at $z = 0.5$ and highlight one borderline case with a bar length of 2.1 kpc and bar strength $A_2 = 0.4$. Synthetic images were produced with Monte Carlo radiative transfer and realistic post-processing, and analysed with ellipse fitting and Fourier decomposition, as well as the recently constructed Zoobot analysis. Results were compared to idealised, noise-free stellar mass maps. In the illustrative case the bar is clearly detected in the mass map and remains visible in the Euclid VIS $I_{\rm E}$ filter, where Zoobot also classifies it as barred, but becomes undetectable in $Y_{\rm E}$ and in the VIS-NISP RGB composite, with all methods failing outside VIS. Extending to the full $z = 0.5$ sample, Zoobot recovers only 31/141 galaxies, while $A_2$ and ellipse fitting perform better (80/141 and 67/141) but still miss many short or weak bars. When non-detections are counted as unbarred, the bar fraction of 44 percent falls to $12\!-\!33$ percent depending on the method. These results demonstrate the strong impact of observational effects on bar detectability and motivate bar-fraction estimates which incorporate realistic instrumental conditions across redshift in cosmological simulations.

Galaxies and galaxy clusters trace the same cosmic density field, but their statistics have been modeled separately in cosmological analyses. We present a unified, simulation-based framework to model them using the galaxy-halo connection. Our analysis includes cluster lensing, galaxy clustering, and galaxy-cluster cross-correlation. We validate our method on the FLAMINGO hydrodynamic simulation. Relative to the cluster-only approach, combining these probes improves the $\sigma_8-\Omega_m$ figure of merit by a factor of 15. Our framework enables stringent tests of cosmological models and exploits small-scale information.

We report the discovery and characterization of TOI-6692 b, an eccentric (e~0.54) Jupiter on a 130-day orbit. TOI-6692 b was first detected as a community TESS Object of Interest (cTOI) by the Visual Survey Group and the Planet Hunters group as a single transit candidate via TESS observation. The period was subsequently confirmed via radial velocity monitoring from the Planet Finder Spectrograph on the 6.5m Magellan telescope. Additional radial velocities were acquired with the CHIRON, FEROS, and CORALIE spectrographs. LCOGT ground-based photometric follow-up was conducted over 2 weeks to detect another transit and refine the period. Although we did not detect an ingress or egress of the 11.04 hr transit, we did detect a possible in-transit signal in the multi-night data and provide an updated ephemeris for future monitoring. TOI-6692 b is one of few planets with orbital periods longer than 100 days that have a secure mass, radius, and eccentricity detection. As with most giant planets at these orbital periods, the eccentricity of TOI-6692 b is lower than that expected of planets undergoing high-eccentricity tidal migration, but is more consistent with the expectations of planet-planet scattering outcomes. A long-term radial velocity trend was detected and further monitoring is warranted to determine the outer companion period. TOI-6692 b is also one of few TESS single transit targets that have its period eventually confirmed via follow-up photometric campaigns timed to capture transits despite the relatively large ephemeris uncertainties. Such efforts highlight the capabilities of night-to-night stability on ground-based photometric facilities today.

Tilted accretion disks in the magnetically arrested (MAD) state may be present in X-ray binaries and active galactic nuclei such as Sgr A* and M87. We have carried out 3D global GRMHD simulations to study the evolution of these accretion flows as a function of black hole spin and misalignment angle. Prograde MADs align with the spin through a two-stage process: an initial rapid alignment phase that operates on the magnetic flux saturation timescale, followed by a slower, spin-independent phase. In contrast, retrograde MADs remain persistently misaligned regardless of the black hole spin, displaying solid-body precession at rates four times higher than weakly magnetized flows at the same spin magnitude. By deriving torque equations in ideal GRMHD and evaluating them in a frame aligned with instantaneous disk orientation, we demonstrate that electromagnetic (EM) torques always act to align the disk with the BH spin, but are countered by opposing hydrodynamic fluxes in retrograde flows. We further develop a preliminary empirical model to explain the cause of two-stage prograde alignment and discuss the possibility of alignment in the retrograde MAD. Strongly magnetized, retrograde, misaligned accretion disks provide a candidate scenario for the low-frequency quasi-periodic oscillations in black hole X-ray binaries.

We present the result from a comprehensive laboratory and on-sky characterization of the commercial spectrograph system consisting of a PIXIS 1300BX charge-coupled device (CCD) camera and an IsoPlane 320A spectrograph as part of the preparation of the forthcoming all-sky spectroscopic survey of nearby galaxies (A-SPEC). In the laboratory, we have quantified readout noise, dark current, gain, and full-well capacity via bias, dark, and photon transfer curve analysis at all acquisition modes. To do that, we have developed a gradient correction technique to address row-dependent signal gradients in the image, which are caused by the shutter-less condition of our CCD camera test setup. The technique successfully reproduces the values in the manufacturer specifications. We also have measured quantum efficiency exceeding 80% from 400--800 nm and $\gtrsim$ 90% between 450--750 nm, with sub-second persistence decay, making it ideal for rapid, multi-object spectroscopy. Using a set of diffraction gratings (150, 300, and 600 gr mm$^{-1}$), we have evaluated the spatial separability of multiple spectra and spectral resolution. We have conducted a test observation with this spectrograph system at the Seoul National University Astronomical Observatory (SAO) 1 m telescope and successfully demonstrated its capability of multi-object spectroscopy with moderate resolution of $R \approx 600 - 2600$. We release all Python codes for the test and recipes to facilitate further instrument evaluations.

We present results from XMM-Newton observations of ten high-redshift ($0.81 < z < 1.17$) galaxy clusters selected from the CAMIRA catalog based on high richness ($N > 40$). These massive clusters, identified in the Hyper Suprime-Cam Subaru Strategic Program field, provide an ideal sample for probing the dynamical state of the intracluster medium (ICM) in the early Universe. We performed uniform X-ray imaging and spectral analyses to measure the ICM temperature and bolometric luminosity, and investigated cluster morphology through offsets between the brightest cluster galaxy (BCG) and the X-ray peak. Extended X-ray emission was detected from all targets, but only one system was classified as dynamically relaxed, indicating a low relaxed fraction ($\sim 10\%$) at high redshift. By combining this high-$z$ sample with a lower-redshift CAMIRA cluster sample, we derived scaling relations among richness, temperature, luminosity, and mass. The results are broadly consistent with predictions from both the self-similar model and the baseline model incorporating the mass--concentration relation. We find no significant redshift evolution, strengthening the view that cluster scaling relations are largely established by $z \sim 1$. We also examined the AGN fraction among member galaxies and found significantly higher AGN activity in high-redshift clusters, particularly in the outskirts, suggesting enhanced AGN triggering during early cluster assembly and a possible connection to the thermodynamic state of dynamically young clusters. These findings provide new insights into the formation and evolution of massive clusters and the thermodynamic history of the ICM, and complement large-area X-ray surveys such as eROSITA.

We compute the density and velocity profiles along the tail induced by a body of mass $M$, embedded in the midplane of a vertically-stratified media with scaleheight $H$, adopting a one-dimensional model as in the Bondi-Hoyle-Lyttleton problem. In analogy to what occurs in the case of a homogeneous medium, there exist a family of solutions that satisfy the boundary conditions. A shooting method is employed to isolate those solutions that fulfill a specific set of physical and mathematical constraints. The tail is found to be both densest and slowest when the scaleheight $H$ is equal to the gravitational radius $\xi_{0}\equiv GM/v_{0}^{2}$, where $v_{0}$ its relative velocity with respect to the medium. The location of the stagnation point is evaluated as a function of $H$ and $\xi_{0}$, and an empirical fitting formula is provided. While the distance to the stagnation point is maximized when $H\simeq \xi_{0}$, the mass accretion rate attains its maximum value for $H \ll \xi_{0}$ at fixed surface density. When instead the midplane density is held constant and $H$ is varied, the accretion rate hardly changes once $H$ exceeds about $2\xi_{0}$. Additionally, we investigate how both the drag force resulting from mass accretion and the gravitational drag arising from its tail depend on $H/\xi_{0}$. We highlight how the effect of varying the degree of mixing in the tail influences the resulting drag force. Finally, for the particular case of an infinitely thin layer, we provide a simple analytical solution, which may serve as a useful pedagogical reference.

Filaments are crucial components of the cosmic web, representing the extensive and aligned distributions of galaxies and gas. Using the Five-hundred-meter Aperture Spherical radio Telescope (FAST), we report the detection of a filament in the Ursa Major supergroup using atomic-hydrogen (HI) observations. This filament consists of sixteen various types of galaxies and five starless gas clumps, spanning a length of approximately 0.9 Mpc. Notably, it is extremely thin, with a thickness comparable to the diameter of a galaxy. We observed a galaxy-filament spin alignment and a velocity gradient within the filament. These findings strongly suggest a cold accretion flow along the filament, potentially contributing to the formation and growth of the galaxies. The thin filament, as a small group, is likely to be merged into the Ursa Major supergroup in the context of hierarchical structure formation.

Galaxies undergo perturbations, either gravitational or hydrodynamic in origin, which can generate extragalactic structures such as rings and tails, where in situ star formation may take place. We selected a sample consisting of JO201 and JW100, undergoing ram-pressure stripping, and NGC 5291 and NGC 7252, formed through gravitational interactions, to investigate how different perturbation mechanisms influence dust content and star formation in extragalactic features. In both cases, star formation can be observed outside the main disks of the galaxies. We present new results of dust attenuation for JO201 and JW100, while for NGC 5291 and NGC 7252 we use results from our previous study, based on high-resolution observations obtained with the Ultraviolet Imaging Telescope onboard AstroSat. Dust attenuation is determined from the ultraviolet continuum slope ($\beta$) calculated using the FUV-NUV colour, and the star formation rates of the star-forming knots are corrected accordingly. It is seen that dust attenuation and dust-corrected SFR densities of the knots in the ram-pressure stripped tails of JO201 and JW100 are comparable to those in the collisional ring of the NGC 5291 system and the tidal tails of the NGC 7252 system. We conclude that, though the formation scenarios of the tails of JO201 and JW100, the NGC 5291 ring, and the NGC 7252 tails are different, their dust content and star formation activity are notably similar.

The circumgalactic medium (CGM) is a multi-phase, dynamic interface between galaxy and the intergalactic medium, providing crucial diagnostics of galaxy evolution. However, direct evidence for a hot (million-Kelvin) CGM around present-day L* galaxies remains elusive. Here, we present the first systematic search of the hot CGM around nearby (< 50 Mpc) L* galaxies, by stacking their X-ray images and spectra from the SRG/eROSITA all-sky survey. Significant diffuse X-ray emission is detected out to ~ 50 kpc, with spectral signatures consistent with a hot gas but arguing against a predominantly non-thermal origin. The radial distribution and total amount of the hot gas are in agreement with prediction by IllustrisTNG simulations. The constraints on the hot CGM derived in this study hold promise for calibrating key physical processes in next-generation cosmological simulations.

We introduce a new photometric catalog of RR Lyrae variables (RRLs, $\sim$300,000) mainly based on data available in public datasets. We also present the largest and most homogeneous spectroscopic dataset of RRLs and Blue Horizontal Branch [BHB] stars ever collected. This includes radial velocity measurements ($\sim$16,000) and iron abundances ($\Delta$S method for 8,140 RRLs, plus 547 from literature). Elemental abundances based on high-resolution spectra are provided for 487 RRLs and 64 BHB stars. We identified candidate RRLs associated to the main Galactic components and their iron distribution function (IDF) becomes more metal-rich when moving from the Halo ([Fe/H]=-1.56) to the Thick (TCD; [Fe/H]=-1.47) and Thin (TND; [Fe/H]=-0.73) disk. Furthermore, Halo RRLs and RRLs in retrograde orbits are $\alpha$-enhanced ([$\alpha$/Fe]=0.27, $\sigma$=0.18), while TCD RRLs are either $\alpha$-enhanced ([Fe/H]$\le$-1.0) or $\alpha$-poor ([Fe/H]$>$-1.0), and TND RRLs are mainly $\alpha$-poor ([$\alpha$/Fe]=-0.01, $\sigma$=0.20). We also identified RRLs associated to the main stellar streams (Gaia-Sausage-Enceladus [GSE]; Sequoia, Helmi, Sagittarius) and we found that their IDFs are quite similar to Halo RRLs. However, GSE RRLs lack the metal-poor/metal-rich tails and their $\alpha$-element distribution is quite compact. The iron radial gradient in Galactocentric distance for TND, TCD and Halo RRLs is negative and it decreases from -0.026, to -0.010, and to -0.002 dex/kpc. The iron radial gradient based on dry Halo (Halo without substructures) RRLs is, within the errors, equal to the global Halo. We also found a strong similarity between iron and [$\alpha$/Fe] radial gradients of Milky Way RRLs and M31 globular clusters throughout the full range of galactocentric distances covered by the two samples.

Detection of stellar flares at hard X-ray is still rare at the current stage. A transient was recently detected by the hard X-ray camera, ECLAIRs onboard the SVOM mission at 11:39:01.2UT on 2025, January 09. Simultaneous monitor in the optical band on the ground by SVOM/GWAC and follow-up spectroscopy enable us to confirm that the transient is caused by a superflare on HD~22468, a RS CVn-type star. The bolometric energy released in the flare is estimated to be $\sim7.2\times10^{37}-1.7\times10^{38}\ \mathrm{erg}$. The hard X-ray spectra of the event at the peak can be reproduced by the ``apec'' model of a hot plasma with a temperature of $106^{+27}_{-22}$~MK. In the optical range, the H$\alpha$ emission-line profile obtained at $\sim1.7$ hrs after the trigger shows a bulk blueshift of $-96\pm20\ \mathrm{km\ s^{-1}}$, which can be explained by either a chromospheric evaporation or a prominence eruption. The ejected mass is estimated to be $3.9\times10^{20}$ g for the evaporating plasma, and to be $3.2\times10^{21}\ \mathrm{g}<M_{\mathrm{p}}<8.8\times10^{21}\ \mathrm{g}$ for the erupted prominence.

Multiphase gas -- ranging from cold molecular clouds ($\lesssim 100\,$K) to hot, diffuse plasma ($\gtrsim 10^6\,$K) is a defining feature of the interstellar, circumgalactic, intracluster, and intergalactic media. Accurately simulating its dynamics is critical to improving our understanding of galaxy formation and evolution, however, due to their multi-scale and multi-physics nature, multiphase systems are highly challenging to model. In this review, we provide a comprehensive overview of numerical simulations of multiphase gas in and around galaxies. We begin by outlining the environments where multiphase gas arises and the physical and computational challenges associated with its modeling. Key quantities that characterize multiphase gas dynamics are discussed, followed by an in-depth look at idealized setups such as turbulent mixing layers, cloud-wind interactions, thermal instability, and turbulent boxes. The review then transitions to less idealized and/or larger-scale simulations, covering radiative supernovae bubbles, tall box simulations, isolated galaxy models including dwarf and Milky Way-mass systems, and cosmological zoom-in simulations, with a particular focus on simulations that enhance resolution in the halo. Throughout, we emphasize the importance of connecting scales, extracting robust diagnostics, and comparing simulations to observations. We conclude by outlining persistent challenges and promising directions for future work in simulating the multiphase Universe.

Results from GRBAlpha, VZLUSAT-2 and GRBBeta CubeSats and their on-board gamma-ray detectors for monitoring transients are summarised in this article. GRBAlpha was a 1U CubeSat launched in March 2021 to a 550 km altitude polar orbit carrying a CsI(Tl) scintillator gamma-ray burst (GRB) detector with a sensitive range of approximately 30-900 keV. It successfully operated for over four years until June 2025 when it de-orbited. VZLUSAT-2 was a 3U CubeSat launched in January 2022 to a 535 km altitude polar orbit and de-orbited in November 2025 after almost four years of smooth operation. It carried on board two GRB detectors very similar to the one used on GRBAlpha. Both missions have detected about 360 gamma-ray transients, including over 170 long and short gamma-ray bursts (GRBs), and including the most intense GRB ever recorded GRB 221009A and the second brightest GRB 230307A. The new family member, GRBBeta 2U CubeSat, integrated at Masaryk University, was launched in July 2024 to a 580 km altitude, 62 degree inclination orbit. It has been detecting GRBs since its launch without any trouble. Gamma-ray detectors on these nanosatellites are based on CsI(Tl) scintillator readout by silicon photomultipliers (SiPMs). These missions also provide a unique opportunity to study the radiation damage of SiPMs in the low Earth orbit environment and monitor the radiation belts. We have demonstrated that CubeSats can be used in missions lasting beyond three years and routinely detect GRBs.

Since viable $f(R)$ gravity models must reconcile early-universe inflation with late-time acceleration, we specifically study the dynamical behavior of such a theory during the matter-dominated to dark-energy-dominated transition epoch. By using $y_{H}(z)$ versus $z$ and the Hubble parameter, we solved the field equations. After appropriately choosing appropriate parameter values , we plotted a series of images. We mentioned that their current values are similar to latest observations data and $\Lambda$CDM-model values. Furthermore, we plotted the fitting of the distance modulus about this model using SN Ia observation data. Therefore we find that the $f(R)$ gravity model is consistent with the SN Ia data, meanwhile, explains the late-stage acceleration of the Universe. Finally, we used various diagnostic tools including $( r, s)$, $( r, q)$, $w_{D}-w'_{D}$ plane, growth rate analysis, statefinder hierarchy and $Om(z)$-diagnostic to evaluate the observational viability of our model, we perform a systematic comparison with the standard $\Lambda$CDM. We found that evolutionary images can be clearly distinguished this model from the $\Lambda$CDM.

Twin stars are predicted to exist in nature if the hadron-to-quark phase transition is strong enough to form a new branch of hybrid stars, separated from the branch of neutron stars. We adopt an agnostic approach, using transition energy density, transition pressure, the discontinuity strength, and a constant speed of sound for quark matter as our parameter space to construct a large possibility of hybrid equations of state, and thereby encapsulating a comprehensive picture of the twin star scenario. First, we report the complete conditions on our parameter space imposed by the general relativistic hydrostatic equilibrium solutions. For a fixed transition energy density and speed of sound for quark matter, we define distinct ranges of transition pressures based on the allowed strengths of discontinuity. Below a maximum transition pressure, a range of discontinuity exists that increases as the transition pressure decreases. Thereby, we identify the loci of the limits on discontinuities as the `witch-hat' curves. Based on the causality limit, the witch-hat curves can be punctured or incomplete. Strong constraints on this picture are drawn from the inferences from GW170817 and the NICER measurements. We computed the maximum mass for twin stars to be $2.05~M_\odot$, the allowed strongest discontinuity in rest-mass density to be $7.76\rho_\mathrm{sat}$, and the upper bound on transition rest-mass density to be $4.03\rho_\mathrm{sat}$. Subsequently, we compute the implications of the stiffness of the quark matter equation of state on this picture. Different confidence levels for observational inferences are considered to assess the extent of inclusion (and rejection) of hybrid equations of state and, consequently, their effects on the limits of the maximum mass of twin stars and phase transition properties.

The success of an astronomical facility is measured by its scientific impact. A principal metric for this impact is the ensemble of peer-reviewed publications based on the observational data obtained by the facility. We present a comprehensive study of the statistics of the 4,190 refereed publications of the Atacama Large Millimeter/Submillimeter Array (ALMA) in the period from 2012 to 2024. The publications have received 169,985 citations and are based on 2,670 ALMA projects totalling 19,265 hours of 12-m-array-equivalent observing time. Our study analyses publication statistics related to various aspects, e.g. science categories, geographical distribution, archival research, time to publication, publication fraction, and citations. We also look into the community and compare ALMA with other facilities. We find that ALMA is a high-impact observatory with an average of 41 citations per publication, ~70% of observed projects published, ~40% of publications making use of archival data in 2024, more than 9,400 unique authors, and a publication evolution following that of HST and VLT. Currently, the impact factor for ALMA publications is larger than that of all other major astronomical facilities. ALMA also plays a pivotal role in very long baseline interferometry (VLBI), substantially contributing to landmark achievements such as capturing the first image of a black hole shadow.

We present the detection and analysis of H2 absorption at z = 4.24 towards the bright quasar J0007-5705, observed with the Very Large Telescope as part of the ESPRESSO QUasar Absorption Line Survey (EQUALS). The high resolving power, R~120000, enables the identification of extremely weak H2 lines in several rotational levels at a total column density of N(H2)~2x10^14 cm^-2, among the lowest ever measured in quasar absorption systems. Remarkably, this constitutes the highest-redshift H2 detection to date. Two velocity components are resolved, separated by only 3 km/s: a narrow (b~1.7 km/s) and a broader (b~6.2 km/s) component. Modelling the rotational population of H2 yields density of log nH/cm^-3 ~ 2.8 with temperature of ~40K (typical of the cold neutral medium) for the narrow component and log nH/cm^-3 ~ 1.4 , T~600K for the warmer, more turbulent component under a moderate ultraviolet (UV) field, suggesting at least several Mpc distance from the quasar. This system reveals the existence of tiny (down to ~0.01 pc), cold overdensities in the neutral medium. Their detection among only 7 damped Lyman-alpha systems in EQUALS suggests that they may be widespread yet usually remain undetected. H2 provides an exceptionally sensitive probe of these structures: even a minute molecular fraction produces measurable Lyman-Werner absorption lines along the extremely narrow optical beam -- the size of the quasar's accretion disc -- when observed at sufficiently high spectral resolution. High-resolution spectroscopy on extremely large telescopes may routinely detect and resolve such structures in the distant Universe, when 21-cm absorption will trace the collective contribution of many cold cloudlets toward larger radio background sources.

A search for pulsars was carried out using a Large Phased Array (LPA) radio telescope at a frequency of 110.4 MHz with a time resolution of 3.072 ms and a frequency resolution of 19.5 kHz with a 2.5 MHz bandwidth used. The survey was conducted in a site with declinations of $+53^\circ < \delta < +87^\circ$. The viewing area is approximately 4100 this http URL. The search was carried out using Fourier power spectra. To increase sensitivity, multiple observations were made in each direction in the sky, and the resulting power spectra were summarized. This made it possible to increase sensitivity by about 5-10 times, depending on the direction in the sky. A blind search opened 35 known pulsars. Estimates of the flux density for 33 pulsars have been obtained.

We study the evolution of primordial black holes (PBHs) formed in the early universe in the presence of a surrounding thermal bath. By incorporating the effects of thermal absorption, we show that PBHs can undergo significant mass growth, leading to extended lifetimes and substantial deviations from the standard Hawking evaporation scenario. We find a critical collapse efficiency, $\gamma_{\rm c} \simeq 0.395$, above which the PBH mass grows without bound. This correction has profound implications for both PBH-induced reheating and dark matter (DM) production. Specifically, we find that the reheating temperature can be suppressed, and the DM parameter space for the PBH reheating scenario can undergo $\mathcal{O}(10)$-$\mathcal{O}(10^4)$ corrections, depending on the PBH formation mass and collapse efficiency. Moreover, our results significantly shift the parameter space in which PBHs can account for the entirety of the DM. To the best of our knowledge, this is the first comprehensive phenomenological study to incorporate thermal absorption into PBH evolution and quantify its impact on cosmological observables.

Understanding the Universe's origins and evolution remains one of the most fundamental challenges in modern cosmology. This white paper explores three key science priorities in this field: unravelling the physics of cosmic inflation, investigating the accelerating expansion of the Universe, and precisely measuring the sum of the neutrino masses. Achieving these goals requires a dedicated survey to map the large-scale structure at high redshift in unprecedented detail. We describe how this can be achieved through a mission concept called SIRMOS, providing a high-throughput, highly multiplexed spectroscopic capability to obtain accurate redshifts for over 100 million galaxies over a wide sky area. Such a survey would leverage the deepest existing wide-area photometric catalogues for targeting, with spectra offering continuous 1.25-2.5~$\mu$m wavelength coverage at moderate resolution, allowing precise redshift measurements in the $1<z<4$ range with minimal bias. We outline the scientific opportunities this presents. Recent years have seen significant advances in instrumentation, including digital micromirror devices, complex telescope mirrors, large detector arrays, and data processing pipelines. While these technologies have been demonstrated in terrestrial applications, such a survey is a unique opportunity to apply these proven capabilities in space to address fundamental questions in cosmology. Participation in such a mission will simultaneously deliver a compelling science case, help align UK Space Agency and STFC strategies, demonstrate the UK's growing capability in end-to-end space missions, and strengthen the national space economy through high-value industrial participation.

From James Webb Space Telescope (JWST) surveys, 31 galaxies with average redshift 7.3 are selected containing large Balmer break, Lyman-$\alpha$ break (V-shaped SED versus $\lambda$). Apart from Hubble Space Telescope (HST) and JWST-NIRCam (Near-infrared camera) photometry for these galaxies, there are JWST-NIRSpec (Near-infrared spectrograph) spectra for 13 galaxies and mid-infrared photometry (mostly JWST-MIRI) for 15 of them. Spectroscopical analyses included Balmer emission lines, Balmer + 4000 angstroms breaks or CaII lines. Spectral energy distribution (SED) fitting with photometry include old and young stellar populations, emission lines associated to HII regions, AGN, interstellar dust extinction and intergalactic extinction from neutral hydrogen. By adopting realistic extinction curves and taking into account the V-shaped SED and low emission at near infrared at rest, the analyses show that AGN contribution in these galaxies ('little red dots' most of them) should be small on average in the reddest wavelengths, though important for few of the 31 galaxies. Average age of the 31 galaxies: $0.61\pm 0.31$(95% CL) Gyr, while the average age of the $\Lambda $CDM universe is 0.70 Gyr. This corresponds to a formation epoch $z_{ form.}>11.2$(97.5% CL). Reddest galaxies present largest ages. One of these very red galaxies gets an age incompatible to be younger than the age of the Universe within $>4.7\sigma$. TP-AGB effect cannot explain this tension. None the less, there may be other uncertainties in the models, so this tension is a provisional result and further research is needed to confirm it.

[HP99] 159 is remarkable as the first supersoft X-ray source (SSS) identified with an evolved helium star donor. With a likely orbital period of 1.164 d or 2.327 d, the origin of the SSS component is controversial, with the two current models being either steady He-burning on the white dwarf surface, or that it is a helium nova in the decaying phase. To help resolve this issue we present extensive new long-term spectroscopy (with SALT) and photometry (at SAAO and with OGLE) of [HP99] 159 which (a) supports 2.327 d as the orbital period, and (b) finds only a small He II radial velocity modulation. The latter is surprising as it implies a very low inclination system, whereas our light curve modelling suggests $i{\sim}50^\circ$, and hence that the He II must be produced in outflowing material further above, or beyond, the disc. We find that the decaying nova model cannot fit our OGLE light curve and the observed SSS flux level. [HP99] 159 has been essentially constant as an SSS over several decades, implying a sustained high level of mass-transfer from its He star donor, making it the only confirmed single-degenerate scenario SN Ia progenitor. We have updated the known SSS binary parameters and find a clear $\sim$1.5 mag difference in their $M_{\rm V}$ when compared to the $M_{\rm V} - \Sigma$ properties of LMXBs, likely due to the larger irradiated areas and more luminous donors.

Forming planetary systems are populated by large numbers of gravitationally interacting planetary bodies, spanning from massive giant planets to small planetesimals akin to present-day asteroids and comets. All these planetary bodies are embedded in the gaseous embrace of their native protoplanetary disks, and their interactions with the disk gas play a central role in shaping their dynamical evolution and the outcomes of planet formation. These factors make realistic planet formation simulations extremely computationally demanding, which in turn means that accurately modeling the formation of planetary systems requires the use of high-performance methods. The planet formation code Mercury-Ar$\chi$es was developed to address these challenges and, since its first implementation, has been used in multiple exoplanetary and Solar System studies. Mercury-Ar$\chi$es is a parallel n-body code that builds on the widely used Mercury code and is capable of modeling the growth and migration of forming planets, the interactions between planetary bodies and the disk gas, as well as the evolving impact flux of planetesimals on forming planets across the different stages of their formation process. In this work we provide the up-to-date overview of its physical modeling capabilities and the first detailed description of its high-performance implementation based on the OpenMP directive-based parallelism for shared memory environments, to harness the multi-thread and vectorization features of modern processor architectures.

We report photometry results of a frequently outbursting dwarf nova, ER Ursae Majoris. To measure the outburst parameters of the system, we carried out analyses of the light curve, periodograms, and O-C diagrams. We investigated the system's behaviour using the ground-based optical data and the Transiting Exoplanet Survey Satellite data. During these observation runs, we scrutinised three superoutbursts and several normal outbursts. We detected ordinary and late superhumps during each of the investigated superoutbursts. We derived the period excess value $\epsilon \approx 3.0(1)\% $. This suggests that over the last 30 years, ER UMa has not shifted on the evolutionary path toward period-bounce objects. Between 1992 and 2022, the interval between two successive superoutbursts (the supercycle length) changed significantly from 42.1 days to 59.6 days, which indicates that the mean mass-transfer rate of ER UMa has been decreasing over this period.

During the star formation process, the interplay between gravity, turbulence, and B-fields is significant, with B-fields apparently serving a regulatory function. However, the extent to which B-fields are decisive relative to turbulence and gravity remains uncertain. This study aims to ascertain the role of B-fields in the fragmentation of molecular clouds. We examine the B-field observed with ALMA at core scales towards the infrared dark cloud G14.225-0.506, focusing on 3 regions with shared physical conditions, and juxtapose it with prior observations at the Hub-filament system scale. Our findings indicate a similar B-field strength and fragmentation level between the 2 hubs. However, distinct B-field morphologies are identified across the 3 regions where polarized emission is detected. In the region N, the large-scale B-field, which is perpendicular to the filamentary structure, persists at smaller scales in the southern half but becomes distorted near the more massive condensations in the northern half. Notably, these condensations exhibit signs of impending collapse, as evidenced by supercritical mass-to-flux values. In the region S, the B-field is considerably inhomogeneous among the detected condensations, and we do not observe a direct correlation between the field morphology and the condensation density. Lastly, in an isolated dust clump located within a southern filament of the northern hub, the B-field aligns parallel to the elongated emission, suggesting a transition in the field geometry. The B-field shows a clear evolution with spatial scales. We propose that the most massive condensations detected in the northern Hub are undergoing gravitational collapse, as revealed by the relative significance of the magnetic field and gravitational potential and mass-to-flux ratio. The distortion of the B-field could be a response to the flow of material due to the collapse.

Strongly lensed quasars in cusp configurations provide a uniquely sensitive probe of small-scale dark matter structure. Using the largest microlensing-free flux ratios for 17 quadruply imaged cusps, we combine these with extensive Monte Carlo simulations of mock lens realizations under cold dark matter (CDM), self-interacting dark matter (SIDM), and fuzzy dark matter (FDM) scenarios. Building on this, we propose a region (minor-axis and narrow major-axis cusp lenses) where flux-ratio anomalies persist even under globally parameterized models ("macromodels") with multipole freedom (capturing disk, asymmetric, or merger-driven structures). Within this region, J1042+1641 is $>3\sigma$ incompatible with both CDM and SIDM. Our results yield a Bayes factor exceeding $100$, providing very strong evidence for FDM over even the most optimistic CDM and SIDM scenarios. As only 11 cusp lenses lie within this region, extending to larger samples will be essential for assessing its statistical generality and for decisively confirming these findings with future microlensing-free flux ratio data.

Context. Among known young stellar objects (YSOs), those exhibiting the most dramatic increases in brightness due to sudden increase in mass accretion rate are eruptive young stars. Gaia20dsk is one of the Gaia-alerted young star candidates that has displayed a double, nonperiodic brightening resembling that of other young eruptive stars. Aims. The goal of this work is to determine the physical and accretion properties of Gaia20dsk to confirm its classification as an eruptive young star. Methods. We combined publicly available optical and near-infrared (NIR) photometry with our X-shooter optical/NIR spectrum. In our analysis, we examined the optical and IR light curves from the bursts, reviewing the color-magnitude diagrams across different bands, reporting the detection of emission lines, and providing estimates of the star's accretion rates during the burst. Results. The optical light curve shows two major and one brief brightening events with a maximum amplitude of ~1.8 mag in the last five years. A classification based on spectral index indicates that Gaia20dsk is a flat-spectrum star. The X-shooter spectrum exhibit emission lines characteristic of accreting low-to-intermediate-mass young stars, displaying features typical of MNor-type objects. The mass accretion rate is between (0.5-1.8)*10^{-6} M_sun/yr. Conclusions. Gaia20dsk is an eruptive YSO that exhibits photometric features similar to those of MNors, including its characteristic brightening amplitude and burst duration, along with similar spectroscopic features and accretion rates.

Circumbinary disk occultation (CBO) systems, in which a misaligned circumbinary disk periodically obscures the central binary, provide unique probes of disk structure and dynamics. However, fewer than ten candidates with measured orbital periods were previously known. In this work, we identify six new CBO candidates, designated ZTF-CBO-1 through ZTF-CBO-6, through a systematic search of Zwicky Transient Facility (ZTF) photometry. These systems exhibit deep ($\gtrsim$1 mag) periodic dimming events with orbital periods ranging from $\sim$30 to $\sim$530 days and occultation durations spanning 32%-77% of their orbital periods. Such large duty cycles rule out the interpretation of circum-companion material occultation. Spectral energy distributions of ZTF-CBO-1 and ZTF-CBO-2 reveal infrared excess indicative of a dust component. TESS observations of ZTF-CBO-1 show no hours- to days-timescale variability during ingress and egress, indicating a smooth disk edge. These discoveries nearly double the known CBO sample, enabling meaningful population-level studies.

It has been suggested since recent time that the magnitude of the interaction between galaxies could be measured from the level of kinematic disturbance of their outer regions with respect to the innermost ones. Here, I proved that the outer north-eastern region of the Small Magellanic Cloud (SMC), a relatively recent stellar structure with a tidal origin from the interaction with the Large Magellanic Cloud, is imprinted by a residual velocity pattern. I obtained from GEMINI GMOS spectra mean radial velocities of star clusters formed in situ, which added to derived mean proper motions and heliocentric distances, allowed to compute their 3D space velocity components. These space velocities differentiate from those that the clusters would have if they instead orderly rotated with the galaxy, i.e., their residual velocities are larger than the upper limit for an object pertaining to the SMC main body rotation disk. The level of kinematic disturbance depends on the SMC rotation disk adopted; galaxy rotation disks traced using relatively old objects are this http URL resulting kinematic disturbance arises in younger and older stellar populations, so that the epoch of close interaction between both Magellanic Clouds cannot be uncovered on the basis of the kinematics behavior of stellar populations populating the outer SMC

While almost everything that astronomers study occurs in the vacuum of space, astronomy itself does not `happen in a vacuum'. Interactions between scientists, as well as outreach to members of the public, improve extensively from access to good communication tools. Social media has become a key tool for communication in astronomy, being widely used by individuals and organizations alike for networking, outreach, and more. However, traditional social media is reliant on benevolent corporations providing a free service without compromising on quality, and the recent takeover and decline of Twitter has shown how vulnerable these platforms can be. In this proceeding, we present The Astrosky Ecosystem, which is an initiative to develop open-source tools and integrations for social media, principally the Bluesky social network. We explain how our project enables the astronomy community to operate its own social media infrastructure, independent of for-profit corporations. We also discuss some of the project's technical aspects, including its use of the AT Protocol for social networking, before concluding with ideas for the future.

The growing body of atmospheric observations of exoplanets from space and ground-based facilities showcases how the great diversity of the planetary population is not limited to their physical properties but extends to their compositions. The ESA space mission Ariel will observe and characterise hundreds of exoplanetary atmospheres to explore and understand the roots of this compositional diversity. To lay the foundations for the Ariel mission, the OPAL Key Science Project is tasked with creating an unprecedented library of realistic synthetic atmospheres spanning tens of elements and hundreds of molecules on which the Ariel consortium will test and validate its codes and pipelines ahead of launch. In this work we describe the aims and the pipeline of codes of the OPAL project, as well as the process through which we trace the genetic link connecting planets to their native protoplanetary disks and host stars. We present the early results of this complex and unprecedented endeavour and discuss how they highlight the great diversity of outcomes that emerge from the large degeneracy in the parameter space of possible initial conditions to the planet formation process. This, in turn, illustrates the growing importance of interdisciplinary modelling studies supported by high-performance computing methods and infrastructures to properly investigate this class of high-dimensionality problems.

The cosmological tensions present in the $\Lambda$ cold dark matter model that have emerged and strengthened over recent years motivate model independent approaches to analysing data. Cosmography is useful for interpreting data in cosmology without imposing assumptions about the field equations of gravity or the matter content in the Universe. Some cosmography methods, denoted covariant cosmography, go even further and stay agnostic to the underlying space-time metric. Due to their high level of generality, covariant cosmography methods can incorporate the anisotropies and inhomogeneities in the observer's vicinity, and may in turn inform about the associated curvature of the relevant structures in our cosmic neighbourhood. Thus, covariant cosmography is a powerful model-independent tool for analysing cosmological data while also enabling the mapping of our local cosmic neighbourhood. In order to be able to explore the covariant cosmography framework to its fullest, it must be tested in tractable models and simulations. In this paper we derive the cosmography of luminosity distance to fourth order in redshift and investigate it in the special case of axially symmetric Szekeres models. We compare the numerical results for the distance-redshift relations of synthetic observers placed within the Szekeres structures with the predictions from the cosmography, and comment on the found level of approximation of the cosmography in relation to other results in the litterature.

The discrepancy of the Hubble parameter H0 as measured from the cosmic microwave background versus that found from traditional distance ladder measurements has produced considerable discussion about the need for another force in cosmology. However the significance of the discrepancy depends on understanding the systematic associated with crowding, metallicity effects, and extinction of the stellar tracers. Thus additional precision distance indicators in the local universe are desperately needed for investigating the H0 tension. The analysis of MUSE archival data makes the case that the Planetary Nebula Luminosity Function (PNLF) has become such an indicator, as the method can reach distances comparable to HST distances of Cepheid at a fraction of a cost, in terms of telescope time and ground-based. With new wide-field spectroscopic facilities it becomes possible to measure distances to early-type galaxies (ETGs) using the PNLF out to 100 Mpc distance, achieving a precise estimate for the H0 value which is independent of the Type Ia supernova calibration, with only single-epoch measurements.

We forecast constraints on an effective dark fluid equation of state parameter $w_{\rm eff}$ that encapsulates modified gravity theories that modifies both the Universe background expansion as well as its large scale structures growth. This is achieved through relating Friedmann equations' dark fluid pressure and density content, thus $w_{\rm eff}$, to modified gravity parameterized models by mean of the Newtonian potential equation parameter $\mu_0$, the gravitational slip parameter $\eta_0$ and a redshift dependent Hubble parameter $H_{0,{\rm bck}}$. We adopt next stage SKA survey specifications, alone or in combination with concurrently expected DR3 Euclid survey release, paying attention to the modeling and recipe of the implementation of the galaxy clustering and lensing probes obtained from the two surveys. We consider two data mock models: one with deviation of the intermediate parameters at the level of 10 \% (yielding however $w_{\rm eff}=-1.03$) and another sub-percently close to $\Lambda$CDM. We found that the three parameters deviation from $\Lambda$CDM could only be detected at 1 $\sigma$ from SKA alone, while this improves to $\sim$ 2 $\sigma$ when we combine with Euclid. An improvement of the order of 30\% on the bounds is reached after projecting the three parameters into a single $w_{\rm eff}$ parameter. However, this affects both cases and thus it does not change much, though it improves the level of detection with respect to $\Lambda$CDM values. We conclude that synergy from both surveys benefits to tighten our constraints, but also that our highly generalized parameterization, although impacting at both the background and the perturbation level, will be hard to disentangle from $\Lambda$CDM at the level at which our forecast is performed and it still needs, to the least, data from more advanced stages of the adopted surveys to hope reach this target.

As the central galaxy in the nearest cluster, M87 provides the best spatial resolution for disentangling the complex interactions between AGN jets and the surrounding environment. We investigate the velocity structure of the multitemperature X-ray gas in M87, particularly in the eastern and southwestern arms associated with past AGN outbursts, using high-resolution spectroscopy from XRISM/Resolve. We analyze a mosaic of XRISM/Resolve observations covering the core of M87, fitting single- and multi-temperature models to spectra extracted from different regions and energy bands. We assess the line-of-sight velocities and velocity dispersions of the hotter ambient and cooler uplifted gas phases, and evaluate systematic uncertainties related to instrumental gain calibration. The hotter ICM phase, traced by Fe He-$\alpha$ emission, shows velocity dispersions below $\sim100$ km/s, and no significant velocity shifts between the arms and a relaxed offset region, suggesting limited dynamical impact from older AGN lobes. In contrast, the cooler gas phase appears to exhibit larger line of sight velocity gradients up to several hundred km/s as well as a higher velocity dispersion than the ambient hot phase, although these conclusions remain tentative pending improvements in the robustness of the gain calibration at lower energies. The first microcalorimeter-resolved map of gas dynamics in M87 supports the uplift scenario for the X-ray arms, with the cooler gas in the east and southwest seemingly moving in opposite directions along the line of sight. The kinetic energy is a small fraction of the gravitational potential energy associated with the gas uplift, and XRISM further suggests that AGN-driven motions may be short-lived in the hot ambient ICM. These constraints provide important input towards shaping future models of AGN feedback.

Electron-capture supernovae (ECSNe) are commonly thought to result in a collapse to a neutron star. Recent work has shown that a thermonuclear explosion is also a possible outcome. The division between the two regimes has not yet been mapped out. In this study, we investigate the conditions under which the transition from thermonuclear explosion to collapse occurs, and what physical mechanisms drive each outcome. We conducted a parameter study of 56 3D hydrodynamic simulations of ECSN in ONe white dwarfs using a level set based flame model implemented in the Leafs code. We varied both the ignition location and the central density at ignition to determine the conditions of the transition regime. Additionally, we explored two different laminar flame parameterizations and how they impact the simulation outcome. From our parameter study, we find a transition density in the range of $\log\rho_c^{ini}=10.0$ and $10.15$ g cm$^{-3}$, depending on the ignition location and utilized laminar flame speed parameterization. Importantly, we find that for sufficiently high central densities, the burned ashes can sink into the core and trap large amounts of neutron-rich material in the bound remnant. In the transition regime between explosion and collapse, we find that the laminar flame speed plays a critical role by suppressing the formation of instabilities and thereby reducing the nuclear energy generation needed to overcome the collapse. We find that a thermonuclear explosion is possible for a wide range of parameters, whereby a more off-center ignition allows for higher central densities to still result in an explosion. Both the conditions at ignition and the flame physics are critical in determining the outcome. Detailed 3D hydrodynamic simulations of the preceding stellar evolution and the ignition process of the thermonuclear flame are necessary to accurately predict the outcome of ECSNe.

Understanding how cosmological parameters influence the cosmic microwave background (CMB) power spectra is a central component of modern cosmology education, but interactive exploration is often limited by computational cost or technical complexity. We present CosmoSlider, a lightweight visualization tool that enables real-time exploration of CMB power spectra as multiple cosmological parameters are varied simultaneously. The tool employs a neural-network emulator implemented using TensorFlow Lite, allowing rapid evaluation of spectra without relying on large grids of precomputed models or on-demand execution of Einstein--Boltzmann solvers. CosmoSlider is available both as an iOS application and as a web-based tool, making it accessible across platforms and suitable for use in classrooms, lectures, and self-guided study. By providing immediate visual feedback, CosmoSlider supports the development of intuition for the physical processes underlying CMB anisotropies and serves as a complementary resource to traditional theoretical instruction.

The nature of MHD waves within inhomogeneous media is fundamental to understanding and interpreting wave behavior in the solar atmosphere. We investigate fast magnetoacoustic wave behavior within gravitationally stratified, magnetically inhomogeneous media, by studying a magnetic environment containing a simple 2D X-type magnetic null point. The addition of gravitational stratification fundamentally changes the nature of the system, including breaking the symmetry. There are two main governing effects: the stratified density profile acts in combination with the inhomogeneous magnetic field, creating a large gradient in the Alfven speed and hence a system replete with refraction. The system is investigated using both numerical simulations and a semianalytical WKB solution (via Charpit's method and a fourth-order Runge-Kutta solver) and we find strong agreement between both. The results show a fundamental difference between the stratification-free and stratified cases, including the formation of caustic surfaces and cusps, and we contextualize these results in the theoretical understanding of fast magnetoacoustic waves.

The growth index $\gamma$ is a powerful trigger for detecting deviations from $\Lambda$CDM. However, its value is often determined by considering an asymptotic constant value that works for all redshift, or else following a chosen parameterisation. Here we formulate the growth index as function of three quantities that could be directly related to observables in redshift bins, $f\sigma_8(z_i)$, $f(z_i)$ and $H(z_i)$. We determine its value and its derivative at observed nodal center of redshift bins and use the shape function method, after showing insightful connection with its underlying governing virtual-work conservation principle, to construct a redshift dependence of the $\gamma$ without assuming a specific parameterization. We then use the resulting shape function to test if we can disentangle between different scenarios where there are discrepancies between its three constituent measured components. We also tested whether it can be used to rule out models of modified gravity, or extended parametric models of the growth index that capture more general behaviors with an additional parameter as function of the scale factor or dark energy. Adopting forecasted measurements from next generation surveys on the three quantities used to construct $\gamma$, we find that reported discrepancies between them could be detected with our method, but at the bins where the errors and lost of precision from our addition of degrees of freedom is small with respect to the deviation of $\gamma$. The same could be concluded for first order extensions to $\gamma$ or common modified gravity models, and to a lesser degree for dynamical dark energy models after supposing the latest DESI values. We conclude that this method is a strong tool to investigate cosmology in a model-independent way especially with forthcoming data delivered by further stage-IV surveys with more stringent uncertainties.(Abridged)

We present a panoramic view of several scaling relations (ScRs) of galaxies of different morphology. The ScRs are obtained from the data of two large surveys (WINGS and MANGA). We analyze the distribution (parameterized by the percent over the total) of galaxies in each region of the diagnostic planes that are set up by means of suitable physical quantities. In addition to this, we discuss the origin of the differences observed in the ScRs between the two samples. Finally, we compare the observational data with the theoretical ones taken from two subsets of the Illustris large scale simulations (TNG50 and TNG100) and we discuss how the comparison should be performed for a correct statistical answer.

The Stage~IV \textit{Euclid} mission will deliver spectroscopic galaxy redshifts together with photometric positions and shapes, enabling cosmological analyses through spectroscopic galaxy clustering (GCsp), photometric galaxy clustering (GCph), weak-lensing cosmic shear (WL), and their cross-correlation (XC). In this work we forecast the constraining power of a Euclid-like survey on the Generalised Dark Matter (GDM) parameters \(w_{\rm gdm}\) and \(c^{2}_{s,{\rm gdm}}\). Our analysis extends previous forecasting pipeline used for standard cold dark matter. For GCsp, we adopt a semi-analytic nonlinear RSD model, with free terms for each bin. For the photometric probes, we compute the nonlinear GDM matter power spectrum using dedicated simulations, and we modify the lensing and clustering window and the intrinsic-alignment prescription. We consider several survey configurations and explore three fiducial values of \(\sigma_8\) motivated by current CMB and low-redshift measurements. In an optimistic setting, for fiducial values \(\sigma_8 \simeq 0.81\) and \(\sigma_8 \simeq 0.77\), we find relative errors of \(4.01\%\) (GCsp), \(5.01\%\) (GCph+WL+XC), and \(1.96\%\) (all probes) on \(c^{2}_{s,{\rm gdm}}\), and \(3.26\%\) (GCph+WL+XC) and \(1.85\%\) (all probes) on \(w_{\rm gdm}\). For a lower fiducial value \(\sigma_8 \simeq 0.67\), that could strongly disfavor $\Lambda$GDM, we find constraints of \(5\%\) (GCsp), \(5\%\) (GCph+WL+XC), and \(2.45\%\) (all probes) on \(c^{2}_{s,{\rm gdm}}\), and \(3.43\%\) (GCph+WL+XC) and \(2.04\%\) (all probes) on \(w_{\rm gdm}\). We also found that, combining all probes, whether in the pessimistic or optimistic settings, a Euclid-like survey will be able to disentangle between the three scenarios. These results show that the survey will be able to constrain the GDM parameters and distinguish between normalisations of the matter fluctuations.(Abridged)

Angular redshift fluctuations (ARF) are a new cosmological observable, recently proposed in the literature. It measures the 2D angular deviations of the average redshift of a given matter tracer under an input redshift shell. Since it depends on the galaxy bias, it can be used to constrain primordial non-Gaussianity through the scale-dependent bias effect. We analyze a sample of quasars built upon the Gaia satellite and unWISE data, Quaia, to measure the local non-Gaussianity parameter $f_{\rm NL}$. This sample is particularly suitable for measuring $f_{\rm NL}$ due to its large volume coverage. We measure the ARF power spectra from the Quaia catalog and combine their information with the 2D (projected) galaxy density and their cross-correlation with the $Planck$ PR4 CMB lensing maps lensing to jointly constrain $f_{\rm NL}$. Assuming the universality relation, we measure $f_{\rm NL} = -3 \pm 14$ at 68% confidence level by combining Quaia quasar angular density and ARF with the CMB lensing. This result is the second tightest constraint on $f_{\rm NL}$ using LSS two-point statistics to date and the best measurement achieved using two-point projected summary statistics, improving by $\sim$25% the previous measurement from Quaia. Our results motivate the inclusion of ARF as an additional cosmological observable in future 2D analysis of upcoming datasets from large surveys.

The field of astronomy is experiencing a data explosion driven by significant advances in observational instrumentation, and classical methods often fall short of addressing the complexity of modern astronomical datasets. Probabilistic graphical models offer powerful tools for uncovering the dependence structures and data-generating processes underlying a wide array of cosmic variables. By representing variables as nodes in a network, these models allow for the visualization and analysis of the intricate relationships that underpin theories of hierarchical structure formation within the universe. We highlight the value that graphical models bring to astronomical research by demonstrating their practical application to the study of exoplanets and host stars.

We explore the feasibility of using Lyman-$\alpha$ (Ly$\alpha$) forests to calibrate the ensemble redshift distribution of the high-redshift tail ($2<z<3$) of photometric galaxies. We use \texttt{CoLoRe} simulations to create mock DESI 5-year Ly$\alpha$ forests and Rubin Observatory LSST 10-year photometric galaxies up to $z=3$, and measure the galaxy redshift distribution via their angular cross-correlations. Due to large redshift-space distortions in the Ly$\alpha$ forest, the conventional $n(z)$ estimator for clustering redshifts does not apply, and we develope a theoretical framework to model the angular cross-correlation directly. Using the simulations, we explore effects of instrumental noise, continuum fitting, and contamination in the Ly$\alpha$ forest, cross-correlation angular scales ($\theta$), and redshift bin size ($\Delta z$) on the signal-to-noise (SNR) of the measurements. We find that continuum fitting methods strongly impact the SNR of the measurements. With our baseline continuum fitting method, \texttt{LyCAN}, at angular scales $\theta\sim10$ arcmin and $\Delta z=0.1$, we measure the cross-correlation signal at $24\sigma$. If the shape of the redshift distribution and galaxy bias evolution are known well for $z<2$, the cross-correlation can constrain the mean redshift of the galaxy sample to $\sigma_z/(1+\bar{z}) = 0.006$ at a mean redshift of $\bar{z}=2$. This demonstrates that Ly$\alpha$ cross-correlation is a reliable and promising method to calibrate the high-redshift tails of photometric Stage IV galaxy surveys.

We present near- and mid-infrared spectra of eight Low-Luminosity Active Galactic Nuclei (LLAGN), spanning nearly four orders of magnitude in black hole mass and Eddington ratio, obtained with JWST/NIRSpec and MIRI as part of the ReveaLLAGN program along with identical archival data of Cen A. The high spatial resolution of JWST cleanly separates AGN emission from host-galaxy contamination, enabling detections of high-ionization potential lines more than an order of magnitude fainter than previously measured. Emission-line diagnostics reveal a transition at log($L_{bol}/L_{Edd}$) ~ -3.5, where the spectral energy distribution becomes increasingly deficient in ultraviolet photons. We find that rotational H$_2$ excitation temperatures are elevated (~500 K higher) compared to both higher-luminosity AGN and star-forming galaxies, while the H$_2$(0-0)S(3)/PAH$_{11.3 \mu m}$ ratios are consistent with those observed in the AGN population. We discuss the possible roles of outflows, jets, and X-ray dominated regions in shaping the interstellar medium surrounding LLAGN. Silicate emission at ~10 $\mu$m, localized to the nuclear region, is detected in most ReveaLLAGN targets. This dataset offers the first comprehensive JWST-based characterization of infrared emission lines in the nuclear regions of LLAGN.

The environs of other stellar systems may be directly probed by analyzing the cometary activity of interstellar objects. The recently discovered interstellar object 3I/ATLAS was the subject of an intensive worldwide follow-up campaign in its pre-perihelion approach. Now, 3I/ATLAS has begun its post-perihelion departure from the Solar System. In this letter, we report the first post-perihelion blue-sensitive integral-field unit spectroscopy of 3I/ATLAS using the Keck Cosmic Web Imager on November 16, 2025. We confirm previously reported CN, Fe, and Ni outgassing along with detections of carbon chain molecules $\mathrm{C}_2$ and $\mathrm{C}_3$. We calculate production rates for each species. We find Fe and Ni production rates of $\mathrm{Q_{Fe}} = (9.55\pm3.96)\times10^{25}$ atoms s$^{-1}$, and $\mathrm{Q_{Ni}} = (6.61\pm2.74)\times10^{25}$ atoms s$^{-1}$, resulting in a ratio of $\log(\mathrm{Q_{Ni}} / \mathrm{Q_{Fe}}) = -0.16\pm0.03$, which matches Solar System comets well and continues the pre-perihelion trend of declining $\log(\mathrm{Q_{Ni}} / \mathrm{Q_{Fe}})$ with $r_h$. We investigate the radial distributions of these elemental species and find characteristic $e$-folding radii of 3880$\pm$39 km for Ni, 6053$\pm$68 km for CN, 4194$\pm$45 km for $\mathrm{C}_2$, and 3833$\pm$45 km for $\mathrm{C}_3$. Compared to pre-perihelion measurements, these radii have increased by a factor of $\sim$6.5--7. Our post-perihelion observations reveal that 3I/ATLAS continues to exhibit cometary behavior broadly consistent with Solar System comets.

We report on the operation of a 13 g PbWO$_4$ crystal, grown from archaeological Pb and operated as a cryogenic calorimeter in an underground environment. Read out with a Ge thermistor, the detector achieves a low energy threshold and, for the first time, enables the derivation of a dark matter exclusion limit using PbWO$_4$ as target material, for both spin-dependent interactions on neutrons and spin-independent interactions. Although limited in mass and not representative of the final RES-NOVA detector design, this prototype demonstrates effective control of mechanical vibrations and low-energy noise in a cryogenic system, which is a key requirement for rare-event searches. The experiment therefore provides a proof of principle for the RES-NOVA detection concept, validating the use of archaeological Pb-based PbWO$_4$ crystals, low-background operation, and robust data-analysis procedures. These results establish a solid technological and methodological foundation for future RES-NOVA detectors employing larger target masses and advanced thermal readout technologies.

The density of ultralight dark matter can be modified in the vicinity of macroscopic bodies when the dark matter possesses quadratic couplings to the Standard Model. If these couplings are sufficiently strong, Earth's atmosphere acts to shield the dark matter, thereby limiting the effectiveness of laboratory-based experiments. Experiments performed at altitudes exceeding the dark matter de Broglie wavelength experience the same orbit-averaged field amplitude as in the absence of scattering. Quantum clocks are capable of detecting variations in fundamental parameters due to the dark matter background. If based on the International Space Station, they are therefore well-suited to probe dark matter masses $m_{\rm DM}\gtrsim 10^{-9} \text{\, eV}$. Moreover, when the dark matter de Broglie wavelength is smaller than Earth's radius ($m_{\rm DM} \gtrsim 10^{-10}$ eV), the dark matter profile around Earth exhibits a dipole feature. In Low Earth Orbits this dipole temporally modulates potential dark matter signals. This provides a powerful cross-check of the orbit-averaged effect and can enhance the sensitivity of these experiments. We find optical clocks could give rise to world-leading constraints in some cases. Orbiting nuclear clocks could probe even more of the parameter space inaccessible to ground-based experiments.

An effective operator is exactly equivalent to the long-wavelength form of the $M1$ operator in transition matrix elements. It allows us to analytically and numerically analyze the $M1$ contribution to the $\alpha(d,\gamma)^6$Li reaction. Isoscalar $M1$ transitions from an initial $S$ wave are shown to be forbidden in radiative capture reactions when distortion is neglected in the initial state. A calculation in a three-body model with proton, neutron, and a structureless $\alpha$ interacting through effective forces leads to a negligible $M1$ $S$-factor at small energies. The dominant $M1$ contribution comes from transitions from an initial $S$ wave to isospin 1 components of the $^6$Li ground state. It is suggested that using this effective $M1$ operator in other models should clarify the origin of large discrepancies between $M1$ $S$-factors appearing in the literature.

Gravitational waves (GWs) in the $10^{-3}-0.1$ Hz band encode unique signatures of the early universe and merging compact objects, but they are beyond the reach of existing observatories. Theoretical models suggest that the Moon could act as a resonant detector, but the unknown influence of its rugged surface and heterogeneous interior has cast doubt on this prospect. Here, we resolve this long-standing uncertainty by constructing the first high-resolution, structurally realistic model of the lunar GW response. We achieve this by combining high-fidelity spectral-element simulations with the analytical power of normal-mode perturbation theory, thereby resolving topographical effects down to $3.7$ km grid spacing while maintaining the capacity to discern global free-oscillation patterns. This dual-methodology approach not only recovers the expected predominant quadrupole ($l=2$) oscillation mode, but also exposes a systematic signal amplification of $(10-20)\%$ in thick-crust regions. This enhancement is traced by our normal-mode analysis to a mode-coupling process, in which the original quadrupolar oscillation induced by the passing GWs distributes energy into a series of higher-order modes, the hybridized eigenmodes of the laterally heterogeneous Moon. Near certain eigen-frequencies and at specific locations, we observe up to tenfold amplification, highlighting the power of numerical simulations in resolving these structurally fine-tuned features. Our work establishes the Moon as an accurately calibrated resonant GW detector, and the resulting amplification maps provide quantitative guide for the optimal landing site selection.

The nuclear equation of state, which determines the structure and properties of neutron stars, remains subject to substantial theoretical uncertainties, leading to model dependence in predicted observables. Universal relations have emerged as a powerful tool to mitigate this dependence by linking neutron star observables in a framework-independent manner. In this work, we introduce a new universal relation that \emph{bridges} finite nuclei and neutron stars through the dimensionless quantity $\zeta = \beta_{1.4}\tilde{L}^{-1}$, which couples the compactness of a $1.4~M_{\odot}$ neutron star to the slope of the nuclear symmetry energy at saturation. The relation is examined under a broad set of relativistic energy density functionals with point-coupling and meson-exchange interactions, as well as non-relativistic Skyrme functionals. We demonstrate that $\zeta$ exhibits a strong exponential correlation with the electric dipole polarizability $\alpha_D$ in finite nuclei across all considered equations of state. By exploiting experimental $\alpha_D$ data for selected neutron-rich nuclei, we constrain $\zeta$ and translate these constraints into equation-of-state-independent bounds on the neutron star radius $R_{1.4}$ and the symmetry-energy slope $L$, providing insights into the properties of neutron star matter.

Current multi-ton detectors put stringent constraints on the GeV-scale galactic dark matter, pushing the allowed cross-section almost towards the neutrino fog, yet remain mostly insensitive to the light dark matter. Cosmic rays can upscatter the non-relativistic halo dark matter particles, making a sub-population of them gain sufficient kinetic energy to be discernible in current direct search experiments. In this work, we explore this alternate strategy to probe sub-MeV electrophilic dark matter boosted by cosmic rays with the latest data of LZ 2025 (WS2024 run) and improve the constraint on the MeV scale dark matter by almost $\sim\mathcal{O}(1)$ compared to the previous XENONnT limit for energy-independent cross-section. Using realistic energy-dependent cross-sections, we also analyse such a scenario, where the associated mediator mass plays a crucial role in governing the event rate and hence the expected limits too. With energy-dependent cross-sections, our obtained limits also remain stronger than the existing constraints from current direct detection experiments. Even compared to the limits from the neutrino detectors with a larger target size, LZ 2025 can put stringent constraints in certain parameter space of the mediator, excluding the previously unexplored regions.

We explore dark matter like fluids in a spherically symmetric Lemaitre Tolman Bondi (LTB) minisuperspace, tracking how symmetry properties of the Hamiltonian constraint control the emergence of effective dark sources in General Relativity (GR) and Horava Lifshitz (HL) gravity. We first deform the GR Hamiltonian by adding an extra weight $+1$ density to the potential. We show that potential deformations of this type leave the (reduced) Dirac algebra unchanged and the modification is naturally reinterpreted as an effective anisotropic stress energy contribution. While the fluid reproduces an isothermal-like mass scaling, its pressure anisotropy prevents it from giving flat rotation curves. We then turn to HL gravity, where the deformed Dirac algebra induces a controlled nonconservation law for an emergent dust component. Generalizing earlier results, we identify a restricted class of LTB backgrounds for which the HL source term yields a positive scaling dark matter density, consistent with ghost-freedom, and recovery of GR in the infrared. The analysis is conditional on a prescribed background: obtaining a fully backreacted areal radius solution consistent with the HL field equations is left as a natural direction for future work.

Wet extreme mass-ratio inspirals (wet EMRIs), which arise from stellar-mass black holes inspiral into supermassive black holes (SMBHs) within the gas-rich environments of Active Galactic Nuclei (AGN), are primary sources of gravitational waves (GWs) for space-borne detectors like LISA, TianQin, and Taiji. Unlike "dry EMRIs", which form through gravitational scattering in nuclear star clusters, wet EMRIs are naturally accompanied by interactions with accretion disks, offering rich multi-messenger science opportunities. They are distinct in generating transient electromagnetic (EM) signals, such as quasi-periodic eruptions (QPEs), which serve as valuable probes of accretion disk physics and SMBH environments. Their GW signals provide an unprecedented precision of the order of $O(10^{-4}\sim 10^{-6})$ in measuring SMBH mass and spin, enabling the calibration of traditional EM techniques and offering insights into jet formation models. Additionally, wet EMRIs serve as bright and dark sirens for cosmology, facilitating percent-level precision measurements of Hubble parameter through AGN host identification or statistical association. These systems hold immense potential for advancing our understanding of black hole dynamics, accretion physics, and cosmology.

The Wide Field Survey Telescope (WFST) is a dedicated photometric surveying facility built jointly by the University of Science and Technology of China (USTC) and the Purple Mountain Observatory (PMO). Since many of its scientific objectives rely on near-real-time data for effective analysis, prompt processing of WFST images is of great significance. To meet this need, we adapted the Rubin Observatory Legacy Survey of Space and Time (LSST) science pipelines to handle the data collected by WFST. This paper presents the complete data processing workflow, from ingestion of raw images to the distribution of alerts, and details the primary data products generated by our pipeline. Researchers using data processed by this pipeline can refer to this document to fully understand the data processing procedures.

Pulsar scintillation observations have revealed ubiquitous discrete scintillation screens in the interstellar medium. A major obstacle in identifying the nature of these screens is the uncertainty in their distances, which prevents precise correlation with known structures in the Milky Way. We used the Five-hundred-meter Aperture Spherical radio Telescope (FAST) to observe PSR B1237+25, PSR 1842+14, and PSR 2021+51. We detected 10 scintillation arcs in PSR B1237+25, 1 in PSR 1842+14, and at least 6 in PSR 2021+51. By modeling the annual modulation of these scintillation arcs, we constrained the distances of the scintillation screens, as well as the anisotropic scattering directions and the projected velocities in those directions. The scintillation screens are distributed throughout the entire paths between Earth and the pulsars. Among these, the distance to the main scintillation screen toward PSR B1237+25 is $267^{+32}_{-28}$ pc, the scintillation screen toward PSR B1842+14 is at a distance of $240^{+210}_{-120}$ pc, and the main scintillation screen toward PSR B2021+51 is located at $887^{+167}_{-132}$ pc. Several screens in our sample appear at distances coinciding with the Local Bubble boundary, particularly the brightest scintillation arc toward PSR B1237+25. We provide a substantial sample of scintillation screen measurements, revealing the rich plasma density fluctuation structures present in the Milky Way.

In light of the recent results from the Atacama Cosmology Telescope (ACT), which have provided a notable shift in the constraints on $(n_s, r)$ and placed several otherwise viable models of inflation in tension with the latest data, we investigate the possible effects that radiative corrections can have on $\xi$-attractor and $\alpha$-attractor models of inflation. These models, which share much in common with Starobinsky inflation, have likewise been put under pressure by these results. We find that percent (and even sub-percent) level radiative corrections can easily shift both of these classes of inflation models comfortably into the regions of parameter space favoured by the most recent constraints. However, the flexibility under such corrections calls into question to what extent it is possible to precisely pin down model-specific predictions for important cosmological observables.

Free-floating planetary mass objects--worlds that roam interstellar space untethered to a parent star--challenge conventional notions of planetary formation and migration, but also of star and brown dwarf formation. We focus on the multiplicity among free-floating planets. By virtue of their low binding energy (compared to other objects formed in these environments), these low-mass substellar binaries represent a most sensitive probe of the mechanisms at play during the star formation process. We use the HST and its WFC3 and the VLT and its ERIS AO facility to search for visual companions among a sample of 77 objects members of the USco and Taurus young nearby associations with estimated masses in the range between approximately 6-66 M$_{\rm Jup}$. We report the discovery of one companion candidate around a Taurus member with a separation of 111.9$\pm$0.4~mas, or $\sim$18~au assuming a distance of 160~pc, with an estimated primary mass in the range between 3--6~M$_{\rm Jup}$and a secondary mass between 2.6--5.2~M$_{\rm Jup}$ depending on the assumed age. This corresponds to an overall binary fraction of 1.8$^{+2.6}_{-1.3}$\% among low-mass brown dwarfs and free-floating planetary mass objects over the separation range $\ge$7~au. Despite the limitations of small-number statistics and variations in spatial resolution and sensitivity, our results, combined with previous high-spatial-resolution surveys, suggest a notable difference in the multiplicity properties of objects below $\sim$30--50~M$_{\rm Jup}$ between USco and Taurus. In Taurus, a binary fraction of $5.6^{+3.2}_{-2.3}$\% is found for objects with masses below 30M$_{\rm Jup}$, and of $7.8^{+3.0}_{-2.4}$\% for objects with masses below 50M$_{\rm Jup}$, whereas no binary were found among 80 objects over the matching luminosity range in USco, corresponding to an upper limit of $\le$1.2\%.

Inflation with an inflection point potential is a popular model for producing primordial black holes. The potential near the inflection point is approximately flat, with a local maximum next to a local minimum, prone to eternal inflation. We show that a sufficient condition for eternal inflation is $\lambda_1 \leq 3$, where $\lambda_1$ is the index of the `exponential tail,' the lowest eigenvalue of the Fokker--Planck equation over a bounded region. We write $\lambda_1$ in terms of the model parameters for linear and quadratic regions. Wide quadratic regions inflate eternally if the second slow-roll parameter $\eta_V \geq -6$. We test example models from the literature and show this condition is satisfied; we argue eternal inflation is difficult to avoid in inflection point PBH models. Eternally inflating regions correspond to type II perturbations and form baby universes, hidden behind black hole horizons. These baby universes are inhomogeneous on large scales and dominate the multiverse's total volume. We argue that, if volume weighting is used, eternal inflation makes inflection point primordial black hole models incompatible with large-scale structure observations.

Binary black holes (BBHs) forming in the accretion disks of active galactic nuclei (AGNs) represent a promising channel for gravitational-wave production. BBHs are often assumed to form at migration traps, i.e. radial locations where the Type I migration of embedded stellar-mass black holes (BHs) transitions from outwards to inwards. In this work, we test this assumption by explicitly simulating the radial migration of BH pairs in AGN disks under different torque prescriptions, including thermal effects and the switch to Type II migration. We map where and when binaries form as a function of supermassive BH (SMBH) mass, disk viscosity, and migrating BH mass. We find that, for SMBH masses below $10^8 M_\odot$, the majority of pair-up events occur near migration traps ($\gtrsim 80\%$). In contrast, for higher SMBH masses, differential migration dominates and off-trap pair-ups can prevail. Certain disk configurations (e.g., $\alpha = 0.01$, $M_\bullet < 10^6 M_\odot$) present a significant overdensity of pair-ups even in the absence of traps due to traffic-jam accumulations where the gamma profile changes slope sharply. We also investigate hierarchical BBH formation, showing that higher-generation pair-ups cluster more tightly around trap or traffic-jam radii. Our results provide realistic prescriptions for BBH pair-up locations and timescales, highlighting the limitations of assuming fixed BBH formation sites.

Recent DESI results indicate a strong preference for dynamical dark energy (DE) when baryon acoustic oscillation (BAO) measurements are combined with supernovae (SNe) and cosmic microwave background (CMB) data using the Chevallier-Polarski-Linder (CPL) parameterization. We analyze the exponential (EXP) parameterization, which introduces a second-order correction to CPL. We determine and compare the 95% upper bounds on the sum of neutrino masses for three dark energy (DE) models -- $\Lambda$CDM, CPL, and EXP -- across four neutrino mass hierarchies (1 massive/2 massless, degenerate, normal, inverted) and multiple dataset combinations (CMB$+$BAO, CMB$+$BAO$+$PantheonPlus, CMB$+$BAO$+$DESY5), employing both Bayesian and frequentist frameworks with physical lower limits from oscillation experiments (0.059 eV and 0.11 eV). Our results show that CPL yields tighter ($\lesssim10$%) bounds compared to EXP. We further confirm earlier findings that neutrino mass constraints are only mildly sensitive to the assumed hierarchy and that the frequentist bounds are tighter than Bayesian ones. Furthermore, the imposed oscillation lower limits, the datasets used and the DE parameterizations play a crucial role in the inferred cosmological neutrino mass bounds. For the datasets, hierarchies, and DE parameterizations considered, we find no statistically significant evidence for nonzero neutrino mass consistent with oscillation lower limits.

Understanding the nature of dark matter (DM) particles remains a pivotal challenge in modern cosmology. Current cosmological research on these phenomena primarily utilizes cosmic microwave background (CMB) observations and other late-time probes, which predominantly focus on large scales. We introduce a novel probe, the 21 cm forest signal, which can be used to investigate DM properties on small scales during the epoch of reionization, thereby addressing the gap left by other cosmological probes. Annihilation and decay of DM particles, as well as Hawking radiation from PBHs, can heat the intergalactic medium (IGM). This heating suppresses the amplitude of the 21 cm forest 1D power spectrum. Therefore, the 1D power spectrum provides an effective method for constraining DM properties. However, astrophysical heating processes in the early universe can also affect the 21 cm forest 1D power spectrum. In this work, we assess the potential of using the SKA to observe the 21 cm forest 1D power spectrum for constraining DM properties, under the assumption that astrophysical heating can be constrained reliably by other independent probes. Under low astrophysical heating conditions, the 1D power spectrum could constrain the DM annihilation cross section and decay lifetime to $\langle\sigma v\rangle \sim {10^{-31}}\,{\rm cm^{3}\,s^{-1}}$ and $\tau \sim {10^{30}}\,{\rm s}$ for ${10}\,{\rm GeV}$ DM particles, and probe PBHs with masses $\sim {10^{15}}\,{\rm\,g}$ at abundances $f_{\mathrm{PBH}} \simeq 10^{-13}$. These constraints represent improvements of 5-6 orders of magnitude over current limits. Furthermore, the 21 cm forest 1D power spectrum has the potential to exceed existing bounds on sub-GeV DM and to probe PBHs with masses above $10^{18}\,{\rm g}$, which are otherwise inaccessible by conventional cosmological probes.

In our previous paper, we developed an orbit-superposition method for edge-on barred galaxies and constructed a set of dynamical models based on different mock observations of three galaxies from the Auriga simulations. In this study, we adopted 12 cases with side-on bars (three simulated galaxies, each with four different projections). We decomposed these galaxies into different structures combining the kinematic and morphological properties of stellar orbits. We then compared the model-predicted components to their true counterparts in the simulations. Our models can identify (BP/X-shaped) bars, spheroidal bulges, thin discs, and spatially diffuse stellar halos. The mass fractions of bars and discs are well constrained with absolute biases of $|f_{\rm model}-f_{\rm true}|\le0.15$. We recovered the mass fractions of halos with $|f_{\rm model}-f_{\rm true}|\le0.03$. For the bulge components, 10 out of 12 cases exhibit $|f_{\rm model}-f_{\rm true}|\le0.05$, while the other two cases exhibit $|f_{\rm model}-f_{\rm true}|\le0.10$. Then, by tagging the stellar orbits with ages and metallicities, we derived the chemical properties of each structure. For the stellar ages, our models recovered the negative gradients in the bars and discs, but exhibited relatively larger uncertainties for age gradients in the bulges and halos. The mean stellar ages of all components were constrained with absolute biases $|t_{\rm model}-t_{\rm true}|\rm\lesssim1\,Gyr$. For stellar metallicities, our models reproduced the steep negative gradients of the bars and bulges, as well as all different kinds of metallicity gradients in the discs and halos. Apart from the bulge in the simulated galaxy Au-18, the mean stellar metallicities of all other components were constrained with absolute biases of $|Z_{\rm model}-Z_{\rm true}|\rm\le0.5\,Z_{\odot}$.

Intensity interferometry (II) offers a powerful means to observe stellar objects with a high resolution. In this work, we demonstrate that II can also probe internal stellar kinematics by revealing a time-asymmetric Hanbury Brown and Twiss (HBT) effect, causing a measurable shift in the temporal correlation peak away from zero delay. We develop numerical models to simulate this effect for two distinct astrophysical scenarios: an emission-line circumstellar disk and an absorption-line binary system. Our simulations reveal a clear sensitivity of this temporal asymmetry to the system's inclination angle, velocity symmetry, and internal dynamics. This suggests that, with sufficiently high time resolution, II can be used to extract quantitative information about internal kinematics, offering a new observational window on stellar dynamics.

Time series foundation models (TSFMs) are increasingly being adopted as highly-capable general-purpose time series representation learners. Although their training corpora are vast, they exclude astronomical time series data. Observations of stars produce peta-scale time series with unique challenges including irregular sampling and heteroskedasticity. We introduce StarEmbed, the first public benchmark for rigorous and standardized evaluation of state-of-the-art TSFMs on stellar time series observations (``light curves''). We benchmark on three scientifically-motivated downstream tasks: unsupervised clustering, supervised classification, and out-of-distribution source detection. StarEmbed integrates a catalog of expert-vetted labels with multi-variate light curves from the Zwicky Transient Facility, yielding ~40k hand-labeled light curves spread across seven astrophysical classes. We evaluate the zero-shot representation capabilities of three TSFMs (MOIRAI, Chronos, Chronos-Bolt) and a domain-specific transformer (Astromer) against handcrafted feature extraction, the long-standing baseline in the astrophysics literature. Our results demonstrate that these TSFMs, especially the Chronos models, which are trained on data completely unlike the astronomical observations, can outperform established astrophysics-specific baselines in some tasks and effectively generalize to entirely new data. In particular, TSFMs deliver state-of-the-art performance on our out-of-distribution source detection benchmark. With the first benchmark of TSFMs on astronomical time series data, we test the limits of their generalization and motivate a paradigm shift in time-domain astronomy from using task-specific, fully supervised pipelines toward adopting generic foundation model representations for the analysis of peta-scale datasets from forthcoming observatories.

Many stars are components of triple-star systems, or of higher-order multiples. In such systems mass transfer is common, and when the transfer is dynamically unstable, a common envelope forms. As such, it is important to be able to compute the post-common-envelope orbital separations among the various stars comprising the system, and to determine whether the common envelope induces mergers or makes later mergers inevitable. In this paper we compute the results of common-envelope evolution for triples. We employ the SCATTER formalism, a new approach to the computation of post-common-envelope separations. This work has applications to gravitational-wave mergers, Type Ia supernovae, and a broad range of other highly energetic phenomena.

We investigate the non-Gaussian features in the distribution of the matter power spectrum multipoles. Using the COVMOS method, we generate 100\,000 mock realisations of dark matter density fields in both real and redshift space across multiple redshifts and cosmological models. We derive an analytical framework linking the non-Gaussianity of the power spectrum distribution to higher-order statistics of the density field, including the trispectrum and pentaspectrum. We explore the effect of redshift-space distortions, the geometry of the survey, the Fourier binning, the integral constraint, and the shot noise on the skewness of the distribution of the power spectrum measurements. Our results demonstrate that the likelihood of the estimated matter power spectrum deviates significantly from a Gaussian assumption on nonlinear scales, particularly at low redshift. This departure is primarily driven by the pentaspectrum contribution, which dominates over the trispectrum at intermediate scales. We also examine the impact of the finiteness of the survey geometry in the context of the Euclid mission and find that both the shape of the survey and the integral constraint amplify the skewness.

The assumption that photons are massless is a foundational postulate of modern physics, yet it remains subject to experimental verification. Fast radio bursts (FRBs), with their cosmological distances and precisely measured dispersion, offer an excellent laboratory for testing this hypothesis. In this work, we propose an improved distribution function for the dispersion measure arising from extragalactic gas and demonstrate that it provides an excellent fit to mock data. We then apply this distribution to constrain the photon rest mass under the $\Lambda$CDM, $w$CDM, and $w_{0}w_{a}$CDM cosmological models, the last of which is favored by recent DESI baryon acoustic oscillation observations. The corresponding 1$\sigma$ upper limits on the photon mass are found to be $4.83\times10^{-51}\,\mathrm{kg}$, $4.71\times10^{-51}\,\mathrm{kg}$, and $4.86\times10^{-51}\,\mathrm{kg}$, respectively, which are the most stringent constraints derived from FRBs to date. These results indicate that the choice of cosmological model has only a minor impact on photon-mass bounds, demonstrate that FRBs provide robust and reliable constraints, and offer strong empirical support for the massless nature of the photon.

We present JWST/NIRSpec IFU observations of a candidate runaway supermassive black hole at the tip of a 62 kpc-long linear feature at z=0.96. The JWST data show a sharp kinematic discontinuity at the tip, with a radial velocity change of $\approx 600$ km/s across 0.1'' (1 kpc). The velocity gradient, together with the projected post-shock flow velocity of $\approx 300$ km/s, is well described by a simple shock-compression model of a supersonic object, with a velocity of $v_{BH} = 954^{+110}_{-126}$ km/s and an inclination $i=29^{+6}_{-3}$ deg. The previously puzzling kinematics along the linear feature, with the observed radial velocity decreasing from $\approx 300$ km/s near the tip to $\approx 100$ km/s closer to the former host galaxy, are naturally explained as gradual downstream mixing of shocked gas with the circumgalactic medium through turbulent entrainment. The bow shock interpretation is further supported by the morphology of the gas at the tip of the wake and an analysis of the [OIII]/H$\alpha$, [NII]/H$\alpha$, [SII]/H$\alpha$, and [SIII]/[SII] line ratios. The line ratios are consistent with fast radiative shocks and rapid cooling, with best-fit shock velocities that are in agreement with expectations from the black hole velocity and the shock geometry. Energy conservation over the lifetime of the wake suggests a SMBH mass of $M_{BH} \gtrsim 10^7$ M$_{\odot}$. These results confirm that the wake is powered by a supersonic runaway supermassive black hole, a long-predicted consequence of gravitational-wave recoil or multi-body ejection from galactic nuclei.

Traditional spectral energy distribution (SED)-fitting methods for stellar mass estimation face persistent challenges including systematic biases and computational constraints. We present a controlled comparison of machine learning (ML) and SED-fitting methods, assessing their accuracy, robustness, and computational efficiency. Using a sample of COSMOS-like galaxies from the Horizon-AGN simulation as a benchmark with known true masses, we evaluate the Parametric t-SNE (Pt-SNE) algorithm -- trained on noise-injected BC03 models -- against the established SED-fitting code LePhare. Our results demonstrate that Pt-SNE achieves superior accuracy, with a root-mean-square error (sigma_F) of 0.169 dex compared to LePhare's 0.306 dex. Crucially, Pt-SNE exhibits significantly lower bias (0.029 dex) compared to LePhare (0.286 dex). Pt-SNE also shows greater robustness across all stellar mass ranges, particularly for low-mass galaxies (10^9 to 10^10 solar masses), where it reduces errors by 47-53 %. Even when restricted to only six optical bands, Pt-SNE outperforms LePhare using all 26 available photometric bands, underscoring its superior informational efficiency. Computationally, Pt-SNE processes large datasets approximately 3.2 x 10^3 times faster than LePhare. These findings highlight the fundamental advantages of ML methods for stellar mass estimation, demonstrating their potential to deliver more accurate, stable, and scalable measurements for large-scale galaxy surveys.

Astronomy, often perceived as a distant or luxury science, holds immense potential as a driver for sustainable local socio-economic development. This paper explores how astronomy can create tangible benefits for communities through education, tourism, technology transfer, and capacity building. Using case studies from South Africa, Chile, Indonesia, and India, we demonstrate how astronomical facilities and initiatives have stimulated local economies, generated employment, supported small enterprises, and enhanced STEM participation, while simultaneously inspiring a sense of shared global heritage. The analysis identifies both successes and challenges, including unequal benefit distribution, limited local ownership, and sustainability gaps once external funding ends. Building on these lessons, we propose a practical framework/guidelines for designing, implementing, and evaluating astronomy-based community initiatives, rooted in participatory engagement and aligned with the UN Sustainable Development Goals (SDGs). This paper positions astronomy as a catalyst for inclusive growth, demonstrating that investment in the cosmos can translate into grounded, measurable benefits for people and places on Earth.

A small body orbiting around an accreting massive object and periodically crossing its accretion disk is a common configuration in astrophysics. In this work, we investigate the secular evolution of extreme mass-ratio inspirals (EMRIs), in which a stellar-mass object (SMO), e.g., a star or a stellar-mass black hole (sBH), collides with the accretion disk of a central supermassive black hole (SMBH), within a fully relativistic framework. We find (1) the disk always tends to align the SMO no matter what the initial orbital inclination $\iota$ relative to the disk is, (2) the final orbital eccentricity of the SMO captured by the disk is always low though the orbital eccentricity may temporarily grow when the orbital inclination $\iota$ is large and the SMO is an sBH, and (3) via collisions with the accretion disk only, only a small fraction of sBHs that are initially close to the SMBH and close to the disk can be captured by the disk within typical disk lifetime of active galactic nuclei. Two-body scatterings between SMOs in the nuclear stellar cluster play an essential role in randomly kicking sBHs towards the disk and boosting the capture rate.

Galaxies in the nearby Universe, particularly dwarf systems, exhibit inner mass profiles of dark matter haloes that systematically depart from canonical cold dark matter expectations, signalling an interplay between baryonic feedback and the collisionless halo. We update an analytical cusp-core transition model by incorporating the effect of supernova-driven mass loss. Adapting this model to SPARC galaxies, we measure the energy conversion efficiency epsilon, defined as the fraction of supernova feedback energy that is used to change the central dark-matter potential. We find epsilon ~ 0.01 for nearby SPARC galaxies. Building on these measurements, we compare the dynamical energy required for a cusp-core transformation with the feedback energy available over burst cycles and identify a cusp-core transition forbidden region on the halo-stellar mass plane where transformation cannot occur. Galaxies with halo masses from 10^8 to 10^11 M_sun lie outside the forbidden region, whereas ultra-faint dwarf galaxies < 10^8 M_sun, galaxy groups and clusters > 10^11 M_sun fall within it, consistent with their high central densities and the inefficiency of core formation at very low and very high masses. This approach also explains the observed diversity of inner density profiles in low-mass systems, showing that both the star formation rate and the energy conversion efficiency govern them, with the latter emerging as a key parameter setting the strength of the cusp-core transition. Beyond the cusp-core problem, our observationally inferred energy conversion efficiency provides a model independent benchmark that strongly constrains galaxy formation models.

The rapid expansion of the Fast Radio Burst (FRB) field has been accompanied by a simultaneous growth of FRB conferences. While these meetings are essential for interacting with other researchers and establishing collaborations, many remain only accessible to those with substantial travel funding, flexible schedules, or geographical proximity. This introduces barriers that predominantly affect early career researchers (ECRs) and people from under-resourced regions, limiting the growth, diversity, and sustainability of the community. To address these issues, the FRB 2025 conference, held in Montréal in July 2025 with over 200 participants, was designed to prioritize inclusivity and accessibility alongside scientific excellence. In this work, we describe how we implemented these goals, including: organizing committees spearheaded by ECRs, a fully hybrid format including YouTube livestreams, low registration fees, a pedagogical day at the beginning of the conference, local vegetarian catering, and the implementation of flash-talks instead of posters. From a post-conference survey of participants, we were able to assess the effectiveness of our initiatives. Notably, we received very positive feedback from the online participants, which amounted to roughly half of the attendees, especially regarding the livestreams and talk recordings. The pedagogical day was also greatly appreciated. The low registration fees naturally led to challenges, in particular with the audio-visual management, and although areas for improvement were noted, such as poster sessions and support for attendees requiring visas, the conference was generally viewed as a success. Our experience demonstrates that highly accessible, hybrid conferences are possible within modest budgets ($\$20$k CAD), and we outline recommendations for future conferences, both in the FRB field and in other domains.

FarView is a proposed low frequency radio interferometer for deployment on the lunar far side, enabled by the Moon's radio quiet environment. Operating over 1-50 MHz inaccessible from Earth, FarView will open a new observational window and promote discovery class science in cosmology, heliophysics, Galactic and exoplanet astrophysics. The primary science is measurement of the redshifted 21 cm signal from the Cosmic Dark Ages (z=30-100), identified by the Astro2020 Decadal Survey as a priority cosmology discovery area. FarView will deliver 3D tomographic measurements and precision power spectra of neutral hydrogen in a largely linear regime, enabling tests of inflationary initial conditions, primordial non Gaussianity, dark matter properties, neutrino masses, and early dark energy. The reference design consists of 100000 crossed dipole antennas in a dense core-halo configuration spanning 200 sq km. A compact 4 km core with 83000 dipoles maximizes sensitivity to large scale cosmological modes, while 20000 halo elements extending to 14 km provide angular resolution and calibration for foreground characterization. Sensitivity forecasts indicate a 10-sigma detection of the Dark Ages 21 cm power spectrum at z=30 over five years of half duty cycle lunar night observations. An FFT-based EPIC beamformer is identified as an efficient signal processing architecture. Beyond cosmology, FarView will enable interferometric imaging of low frequency solar radio bursts, advancing space weather studies. Additional capabilities include stellar space weather observations, Galactic cosmic ray tomography via free-free absorption, and searches for auroral radio emission from exoplanet magnetospheres, a probe of exoplanet habitability. FarView represents a flagship class opportunity to establish the Moon as a platform for foundational astrophysics while delivering unique observational capabilities.

The flavor evolution of a neutrino gas can show ''slow'' or ''fast'' collective motion. In terms of the usual Bloch vectors to describe the mean-field density matrices of a homogeneous neutrino gas, the slow two-flavor equations of motion (EOMs) are $\dot{\mathbf{P}}_\omega=(\omega\mathbf{B}+\mu\mathbf{P})\times\mathbf{P}_\omega$, where $\omega=\Delta m^2/2E$, $\mu=\sqrt{2} G_{\mathrm{F}} (n_\nu+n_{\bar\nu})$, $\mathbf{B}$ is a unit vector in the mass direction in flavor space, and $\mathbf{P}=\int d\omega\,\mathbf{P}_\omega$. For an axisymmetric angle distribution, the fast EOMs are $\dot{\mathbf{D}}_v=\mu(\mathbf{D}_0-v\mathbf{D}_1)\times\mathbf{D}_v$, where $\mathbf{D}_v$ is the Bloch vector for lepton number, $v=\cos\theta$ is the velocity along the symmetry axis, $\mathbf{D}_0=\int dv\,\mathbf{D}_v$, and $\mathbf{D}_1=\int dv\,v\mathbf{D}_v$. We discuss similarities and differences between these generic cases. Both systems can have pendulum-like instabilities (soliton solutions), both have similar Gaudin invariants, and both are integrable in the classical and quantum case. Describing fast oscillations in a frame comoving with $\mathbf{D}_1$ (which itself may execute pendulum-like motions) leads to transformed EOMs that are equivalent to an abstract slow system. These conclusions carry over to three flavors.

We discuss a model of the universe where dark energy is replaced by electrically-charged extremely-massive dark matter. The cosmological constant has a value of the same order as the mean matter density, consistent with observations, and is obtained classically without fine-tuning.

We propose a novel experimental method for probing light dark matter candidates. We show that an electro-optical material's refractive index is modified in the presence of a coherently oscillating dark matter background. A high-precision resonant Michelson interferometer can be used to read out this signal. The proposed detection scheme allows for the exploration of an uncharted parameter space of dark matter candidates over a wide range of masses -- including masses exceeding a few tens of microelectronvolts, which is a challenging parameter space for microwave cavity haloscopes.

Galactic double white dwarf (DWD) binaries are among the guaranteed sources for the Laser Interferometer Space Antenna (LISA), an upcoming space-based gravitational wave (GW) detector. Most DWDs in the LISA band are far from merging and emit quasimonochromatic GWs. As these sources are distributed throughout the Milky Way, they experience different accelerations in the Galactic gravitational potential, and therefore each DWD exhibits an apparent GW frequency chirp due to differential acceleration between the source and LISA. We examine how Galactic acceleration influences parameter estimation for these sources; and investigate how LISA observations could provide insight into the distribution of matter in the Galaxy.

The MIST experiment aims to detect the cosmological 21-cm signal through sky observations at 25-125 MHz using a wide-beam antenna. The antenna is mounted above the soil and the beam characteristics are highly dependent on the soil's electrical properties. Accurate models for the beam obtained from electromagnetic simulations are crucial for detecting the 21-cm signal. Determining the soil properties to inform the beam simulations is therefore a very high priority for MIST. Here we report the first electrical characterization of the MIST observation site in the Canadian High Arctic, which was conducted in July, 2022. The electrical parameters were estimated using impedance measurements of the instrument's antenna, which is a very advantageous approach for MIST. Our best-fit soil model is consistent with a thawed active layer underlain by permafrost, and the parameters were estimated with a precision close to the requirements for the detection of the cosmological 21-cm signal.

The evolution of density perturbations is analysed in a modified theory of gravity with a nonminimal coupling between curvature and matter. We consider the broken degeneracy between the choices of matter Lagrangian for a perfect fluid, $\mathcal{L}_m=-\rho$ and $\mathcal{L}_m=p$, and determine the differences between their effects on the effective gravitational constant. We review the result for $\mathcal{L}_m=-\rho$ in the quasistatic approximation and show how it can lead to unphysical singular behaviour for late-time dominating models. This divergent regime can be avoided when considering the fully non-quasistatic perturbative equations, although the higher-order nature of the nonminimally coupled theory and the requirement of a physically viable effective gravitational constant strongly constrains the magnitude of these modifications to the action. We find that both of these issues can be removed when considering $\mathcal{L}_m=p$ at late times due to the pressureless nature of non-relativistic matter and provide predictions for inverse power-law models.

We unveil the dynamical equivalence of field theories with non-canonical kinetic terms and canonical theories with a volume element invariant under transverse diffeomorphisms. The proof of the equivalence also reveals a subtle connection between the standard Legendre transformation and the so-called Clairaut equation. Explicit examples of canonizable theories include classes of $k$-essence, non-linear electrodynamics, or $f(R)$ theories. The equivalence can also be extended to the class of mimetic theories.

Dynamical captures of black holes are unique events that provide an exceptional opportunity to probe the strong-field regime of gravitational physics. In this article, we perform numerical relativity simulations to study the events of dynamical capture of two equal-mass nonspinning black holes. We consider a suite of scenarios within a range of initial linear momenta ($p/M=0.095-0.75$) and incidence angles ($\theta=6.36^\circ-2.83^\circ$), and study the emitted Weyl scalar ($\Psi_4$) of each case, as well as the spins and masses of the black holes before and after they merge. We provide a simple analytical model which accurately fits the gravitational-wave emission. We study the dependence of the time interval between the capture and the merger emissions with respect to the incidence angle, which can be well parametrized by a first-order divergent behavior, allowing us to find the angle that separates a scattering event from a dynamical capture. We also find that, in general, the parameters that model the first emission can be well described by linear or exponentially decaying functions in terms of the incidence angle, while others display more complex behaviors that offer valuable insights into the nature of these events.

We derive general formulas for three flavor fractions $(\eta^{}_e , \eta^{}_\mu , \eta^{}_\tau)$ of the high-energy neutrinos originating from a remote astrophysical source by using their flavor ratios $(f^{}_e , f^{}_\mu , f^{}_\tau)$ observed at a neutrino telescope, and diagnose a potential divergence associated with $\eta^{}_\mu$ and $\eta^{}_\tau$ as an unavoidable consequence of the $\mu$-$\tau$ interchange symmetry exhibiting in the $3\times 3$ lepton flavor mixing matrix $U$. We present a complete set of analytical expressions for $(\eta^{}_e , \eta^{}_\mu , \eta^{}_\tau)$ as functions of two typical $\mu$-$\tau$ symmetry breaking parameters in the standard parametrization of $U$, and apply it to the recent IceCube all-sky neutrino flux data ranging from 5 TeV to 10 PeV in the assumption that the relevant sources have a common flavor composition. We also explain why only $\eta^{}_e$ and $\eta^{}_\mu + \eta^{}_\tau$ can be extracted from a precision measurement of $f^{}_e$ and $f^{}_\mu = f^{}_\tau$ in the exact $\mu$-$\tau$ flavor symmetry limit.

In this paper, we investigate periodic orbits of test particles around a deformed Schwarzschild black hole and the resulting gravitational waves. Firstly, we examine the properties of circular orbits and find that circular orbits could disappear when the deformation is large enough. Then, using an orbital taxonomy, we characterize various periodic orbits with a set of triples, which describes the zoom-whirl behaviours. We also calculate the gravitational waveform signals generated by different periodic orbits, revealing the influence of the deformation on the gravitational wave, which can be potentially picked up by future space-based detectors.

In the analysis of complex physical systems, the objective often extends beyond merely computing a numerical solution to capturing the precise crossover between different regimes and extracting parameters containing meaningful information. However, standard numerical solvers and conventional deep learning approaches, such as Physics-Informed Neural Networks (PINNs), typically operate as black boxes that output solution fields without disentangling the solution into its interpretable constituent parts. In this work, we propose GlueNN, a physics-informed learning framework that decomposes the global solution into interpretable, patchwise analytic components. Rather than approximating the solution directly, GlueNN promotes the integration constants of local asymptotic expansions to learnable, scale-dependent coefficient functions. By constraining these coefficients with the differential equation, the network effectively performs regime transition, smoothly interpolating between asymptotic limits without requiring ad hoc boundary matching. We demonstrate that this coefficient-centric approach reproduces accurate global solutions in various examples and thus directly extracts physical information that is not explicitly available through standard numerical integration.