Papers for Monday, Sep 29 2025

The Cherenkov Telescope Array Observatory (CTAO) is an international observatory currently under construction, which will consist of two sites (one in the Northern Hemisphere and one in the Southern Hemisphere). It will eventually be the largest and most sensitive ground-based gamma-ray observatory. In the meantime, a small subarray composed of four Large-Sized Telescopes (LSTs) at the Northern site will begin collecting data in the coming year. In preparation, we present a stereoscopic event reconstruction using graph neural networks (GNNs) to combine information from several telescopes of this subarray. In our previous work, we explored the use of GNNs for the stereoscopic reconstruction of gamma-ray events on simulated data from the Prod5 sample and showed that GNNs provide a better stereoscopic reconstruction. We now compare this approach to the currently foreseen method that analytically combines the output of monoscopic random forests, and explore how GNNs can be used in fusion with the Random forest algorithm in order to provide a more sensitive stereoscopic system.

The study of the last stages of planet formation, also known as debris disks, is fundamental to place constrains on the formation of planetary sized bodies. Debris disks are composed of dust and occasionally small amounts of gas, both released through dynamical interactions of small rocky bodies and dust particles, such as collisions and evaporation. The distribution of the dust can reveal the presence of forming planets and its composition can directly trace that of comets, asteroids and even planets. While we have been observing debris disks for 40 years now, most observations so far have been restricted to the cold outer regions of the system, and therefore information of the terrestrial zone is still missing. The improved spatial resolution, inner working angle and sensitivity that the Habitable Worlds Observatory will provide will enable a much closer look into the structure and composition of debris disks (particularly of its inner region) and enable the search for the forming rocky planets within the disk.

We use astrometric data on 3I/ATLAS compiled by the Minor Planet Center from May 15 to September 23, 2025, and derive an upper limit on any statistically significant deviation from the best-fit gravity-based trajectory. The residuals imply that the non-gravitational acceleration is smaller than $\sim 3 \times 10^{-10}\,{\rm au\,d^{-2}}$. Based on the total mass-loss rate and outflow speed inferred from JWST data on August 6, 2025, we derive lower limits on the mass and diameter of 3I/ATLAS of $3.3 \times 10^{16}\,{\rm g}$ and $5\,{\rm km}$, respectively.

Inertial waves transport energy and momentum in rotating fluids and are a major contributor to mixing and tidal dissipation in Earth's oceans, gaseous planets, and stellar interiors. However, their stability and breakdown mechanisms are not fully understood. We examine the linear stability and nonlinear breakdown of finite-amplitude propagating plane inertial waves using Floquet theory and direct numerical simulations. The Floquet analysis generalizes previous studies as it is valid for arbitrary perturbation wavelengths and primary wave amplitudes. We find that the wavenumber orientation of the most unstable perturbations depends strongly on the wave frequency and weakly on the wave amplitude. The most unstable perturbations have wavelengths that are small relative to the primary wave wavelength for low wave amplitudes, but become comparable for large wave amplitudes. We then use direct numerical simulations to follow the nonlinear breakdown of the wave and examine how the wave energy is either dissipated in a forward cascade or accumulated into long-lived geostrophic modes. Simulations reveal that the conversion efficiency into geostrophic modes increases with increasing wave amplitude, as expected for pumping of geostrophic modes by nearly-resonant triadic interactions. We also find that the conversion efficiency increases with decreasing primary wave frequency, which may be due to the more efficient coupling of quasi-2D waves to geostrophic modes. These results on the stability and breakdown of single plane inertial waves provides additional foundation for understanding the role of inertial waves in rotating turbulence, transport properties of inertial wave beams, and inertial wave propagation in more complex environments such as those with magnetic fields or shear flows.

GRAVITY+ improves by orders of magnitude the sensitivity, sky-coverage and contrast of the Very Large Telescope Interferometer (VLTI). A central part of this project is the development of Gravity Plus Adaptive Optics (GPAO), a dedicated high-order and laser-guide star Adaptive Optics (AO) system for VLTI. GPAO consists of four state-of-the-art AO systems equipping all 8m-class Unit Telescopes (UTs) for the wavefront correction of the VLTI instruments. It offers both visible and infrared Natural Guide Star (NGS) and Laser Guide Star (LGS) operations. The paper presents the design, operations and performances of GPAO. We illustrate the improvement brought by GPAO with interferometric observations obtained during the commissioning of the NGS mode end-2024. These science results include the first optical interferometry observations of a redshift $z\sim4$ quasar, the spectroscopy of a cool brown-dwarf with magnitude $K\sim 21.0$, the first observations of a Class I young star with GRAVITY, and the first sub-micro arcsecond differential astrometry in the optical. Together with the entire GRAVITY+ project, the implementation of GPAO is a true paradigm shift for observing the optical Universe at very high angular resolution.

Planetesimal formation likely lasted for millions of years in the Solar nebula, and the cold classicals in the Kuiper belt are suggested to be the direct products of streaming instability. The presence of minor planetary bodies in the outer Solar System and the exo-Kuiper belts provide key constraints to planet formation models. In this work, we connected dust drift and coagulation, planetesimal formation, N-body gravity, pebble accretion, planet migration, planetary core accretion, gap opening, and internal photoevaporation in one modeling framework. We demonstrate that multiple classes of minor planets, or planetesimals, can form during disk dissipation and remain afterwards, including a scattered group, a resonant group and a dynamically cold group. Significant growth by pebble accretion was prevented by both dynamical heating due to the giant planet in the system and rapid dispersal of the disk towards the end of its lifetime. We also conducted a parameter study which showed that this is not a universal case, where the outcome is determined by the competition for dust between planetesimal formation and pebble accretion. Combining this scenario with sequential planet formation, this model provides a promising pathway towards an outer Solar System formation model.

Circumbinary planets (CBPs) provide a unique window into planet formation and dynamical evolution in complex gravitational environments. Their orbits are shaped not only by the protoplanetary disk but also by the perturbations from two stellar hosts, making them sensitive probes of both early- and late-stage dynamical processes. In this work, we investigate the unusual architecture of the VHS J125601.92-125723.9 system, where a retrograde, nearly polar tertiary orbits an extremely low-mass substellar binary in a hierarchical triple configuration. We find that triple body dynamics can naturally reproduce the observed high eccentricity of the inner binary and the tertiary's near-polar obliquity. However, this configuration alone cannot account for the observed mutual inclination, which is both near-polar and retrograde. This tension suggests two possible formation pathways: either the planet formed in an aligned, protoplanetary disk-like configuration and was later tilted by an additional, undetected fourth companion (below current Gaia limits), or the system formed close to its current state. Stellar flybys, in contrast, are unlikely due to their long timescales. Our results highlight both the explanatory power and the limitations of triple dynamics, and the potential role of hidden companions in shaping extreme planetary architectures.

Photonuclear interactions between ultra-high-energy cosmic ray (UHECR) nuclei and surrounding photon fields are key to understanding the connection between the compositions observed at Earth and those emitted from the sources. These interactions can completely disintegrate a nucleus of iron over trajectory lengths of a few and up to hundreds of megaparsecs, depending on the energy of the UHECR. The stochastic nature of these interactions means that it is not possible to describe them deterministically for a single cosmic ray, and an exact formulation of the probability distributions is not yet available. Current approaches describe these interactions using either Monte Carlo simulations or solving ordinary differential equations that neglect stochasticity. Because of the limitations of these approaches, only partial capture of the process is achieved. This paper presents an analytic probabilistic description of UHECR interactions and the resulting nuclear cascades, establishing their connection to Markov jump processes. The fundamental properties of these cascades are presented, as is the computation of the usual quantities of interest, such as the horizon, spectrum, and composition. The benefits of this description are outlined using astrophysical examples related to extragalactic propagation and UHECR sources.

An international conference Radio Stars in the Era of New Observatories was held at the Massachusetts Institute of Technology Haystack Observatory on 2024 April 17-19. The conference brought together more than 60 researchers from around the world, united by an interest in using radio wavelength observations to explore the physical processes that operate in stars (including the Sun), how stars evolve and interact with their environments, and the role of radio stars as probes of our Galaxy. Topics discussed at the meeting included radio emission from cool and ultracool dwarfs, extrasolar space weather, stellar masers, thermal radio emission from evolved stars, circumstellar chemistry, low frequency observations of the Sun, radio emission from hot stars, applications of very long baseline interferometry techniques to stellar astrophysics, stellar explosive events, the detection of radio stars in the latest generation of widefield sky surveys, the importance of radio stars for understanding the structure and evolution of the Milky Way, and the anticipated applications for stellar astrophysics of future radio observatories on the ground and in space. This article summarizes research topics and results featured at the conference, along with some background and contextual information. It also highlights key outstanding questions in stellar astrophysics where new insights are anticipated from the next generation of observational facilities operating at meter through submillimeter wavelengths.

The origin of the Universe's late-time accelerated expansion remains unknown. The General Relativistic Entropic Acceleration (GREA) theory offers a compelling alternative to $\Lambda$CDM, attributing cosmic acceleration to entropy growth associated with cosmic and black hole horizons, without invoking a cosmological constant. We test GREA against the latest DESI DR2 Baryon Acoustic Oscillations (BAO), multiple Type Ia supernova compilations (Union3, Pantheon$\texttt{+}$, DES-SN5YR), and cosmic microwave background (CMB) distance measurements. While GREA is not nested within $\Lambda$CDM, it achieves a comparable goodness-of-fit, highlighting its potential as a theoretically motivated framework that circumvents some of the fine-tuning issues of the standard $\Lambda$CDM cosmology. We find that the best-fit model features a transient phantom crossing at $z \lesssim 2$, with $w_a\equiv \mathrm{d} w(a=1)/\mathrm{d}a \simeq-0.3$, in good agreement with observations. However, its present-day value $w_0\equiv w(z=0)$ is tightly constrained to be $w_0\simeq-1$. Upcoming low-redshift (i.e. $z < 1$) cosmological probes, from both background and perturbations, will offer promising avenues for further exploring the viability of the GREA theory.

We present a flare temperature study of the highly active M~dwarf Wolf~359 using simultaneous multiband ($u$, $g$, $r$, $i$, and $z$) photometric observations from the Lulin 1-m and 41-cm telescopes. Twelve flares were detected over five nights, with significant brightness increases in the $u$, $g$, and $r$~bands; only three were seen in $i$, and none in $z$. From broadband SED fitting and $g$/$r$ color ratio, we derive an average flare temperature of $5500 \pm 1600$~K, significantly cooler than the canonical 10000~K. We obtained a power-law relation between FWHM flare temperature and energy in the solar-class flare regime and extrapolated it to higher energies, superflare regime. This power-law is consistent with the trends reported for M-dwarf superflares in previous studies, suggesting a common temperature-energy scaling across several orders of magnitude. However, the scatter in the superflare regime increases, indicating that such energetic events may involve more complex physical mechanisms and limiting the applicability of simple blackbody models at the high energy flares. Using our FWHM flare temperature--TRIPOL~$g$ energy relation and the reported flare energy frequency distribution of Wolf~359, we evaluated the potential flare contribution to photosynthetically active radiation (PAR) in the habitable zone. We find that typical solar-class giant flares ($E_{\mathrm{fl,bol}} \sim 9\times10^{31}$~erg, $T_{\mathrm{fl,fwhm}} \sim 6800$~K) are {not frequent enough} to sustain Earth-like net primary productivity. Even under the extreme superflare condition ($\sim$$10^{36}$~erg, $\sim$16500~K), flare activity remains far from meeting the PAR threshold.

Thousands of tight ($<1$ AU) main sequence binaries have been discovered, but it is uncertain how they formed. There is likely too much angular momentum in a collapsing, fragmenting protostellar cloud to form such binaries in situ, suggesting some post processing. One probe of a binary's dynamical history is the angle between the stellar spin and orbital axes -- its obliquity. The classical method for determining stellar obliquity is the Rossiter-McLaughlin effect. It has been applied to over 100 hot Jupiters, but to less than a dozen stellar binaries. In this paper, we present the Rossiter-McLaughlin measurement of EBLM J0021-16, a $0.19M_\odot$ M-dwarf eclipsing a $1.05M_\odot$ G-dwarf on a 5.97 day, almost-circular orbit. We combine CORALIE spectroscopy with TESS photometry of primary and secondary eclipses and star spot modulation. We show that the orbital axis is well-aligned with the primary star's spin axis, with a true 3D obliquity of $\psi=4.01\pm0.54^{\circ}$. EBLM J0021-16 becomes one of only a handful of eclipsing binaries where a true obliquity has been measured. Finally, we derive the M-dwarf's mass and radius to a fractional precision better than 1\%. The radius of the M dwarf is inflated by 6\% ($7.4\sigma$) with respect to stellar models, consistent with many other M-dwarfs in the literature.

HR6819 is the first system with a puffed-up low mass stripped star and a classical Be star whose nature has been confirmed by optical interferometry. It shows the most extreme mass ratio (15.7 +/- 1.1), the lowest stripped star mass (0.270 +/- 0.056 Msun), and one of the shortest orbital periods (40.3266 +/- 0.0016 days) among similar post-interaction binaries. These properties make HR6819 a unique test case for binary interaction physics, in particular the efficiency of mass transfer onto the Be progenitor required to reach such an extreme mass ratio. We reconstruct the possible evolutionary history of the system with grids of MESA simulations spanning mass transfer efficiencies from fully to fifty percent conservative. We show that stable Roche lobe overflow cannot simultaneously reproduce the observed orbital period and extreme mass ratio: the maximum ratio achievable is ~11.5 at ~40 days, even in the fully conservative case. Furthermore, the observed luminosities of both components exceed those expected from their model masses; the luminosity of the stripped star would be consistent with a ~0.7 Msun mass, over twice its dynamical mass. Our results demonstrate that the post-interaction properties of HR6819 cannot be explained by stable mass transfer under standard assumptions.

Heavily obscured Active Galactic Nuclei (AGN), especially Compton-thick sources with line-of-sight column density ($N_{\rm H,los}$) $>$ 10$^{24}$ cm$^{-2}$, are critical to understanding supermassive black hole (SMBH) growth and the origin of the Cosmic X-ray Background (CXB). However, their observed fraction remains significantly below model predictions, due to strong absorption bias, even in the hard X-ray (i.e., above 10 keV) band. We analyze a sample of 26 nearby ($z < 0.1$) AGN from the Swift-BAT 150-month catalog, selected via mid-IR to X-ray diagnostics and observed with NuSTAR and soft X-ray telescopes (Xmm-Newton, Chandra, or Swift-xrt). Using self-consistent torus models (MyTorus, Borus02, and UXCLUMPY), we aim to constrain $N_{\rm H,los}$, the average torus column density, and other geometrical parameters of the obscuring medium. A comparative analysis among the three torus models showed that while estimates of $N_{\rm{H,los}}$ were generally in agreement, Borus02 tended to classify a slightly larger number of sources as Compton-thick AGN (CT-AGN). Building on this comparison, we benchmark two prediction schemes -- a mid-IR/X-ray relation and a machine-learning model -- against our broadband best-fit $N_{\rm H,los}$ measurements to assess which approach more effectively bridges the gap between predicted and measured obscuration, finding that while the former works effectively in the heavily obscured region (log$\rm{N_H} \gtrsim$ 23.5 $\rm{cm^{-2}}$), the latter provides improved accuracy, particularly for Compton-thin to moderately thick regimes (log$\rm{N_H} \lesssim$ 23.5 $\rm{cm^{-2}}$).

A Structural and Thermal Model (STM) has been developed to support the new spaceborne Closed-Cycle Dilution Refrigerator (CCDR), which aims to provide continuous cooling at 100~mK for long-duration astrophysical missions. The STM is based on a hexapod architecture that ensures both thermal decoupling and mechanical robustness during launch. In this paper, we present the characterization of its thermal and mechanical performances. A dedicated experimental setup was used to investigate the thermal behavior of the STM across a broad temperature range. The study reveals limitations of the collar design, with incomplete power interception from thermal boundary resistances and vibration test failure traced to defective strut gluing. These results guide the next STM iteration with optimized collar and strut assembly for reliable CCDR operation in space.

We present new results for the hot Jupiters HAT-P-16b, TOI-1516b, and TOI-2046b, based on photometric observations collected using both space- and ground-based facilities. Ground-based data were collected in the 2020-2024 time span with the 0.6 m telescope (ADYU60) located at the Adiyaman University Application and Research Center (Adiyaman, Türkiye) and the 1.0 m telescope at the Türkiye National Observatory (TUG, Türkiye). Through a combination of fits to our ground-based data, the mid-transit times data from TESS and additional data taken from the literature, we present an updated linear ephemeris for each system. Transit timing variations (TTVs) were analyzed using linear, orbital decay, and apsidal precession models. The resulting BIC($\Delta$BIC) values indicate that the orbital decay model is statistically favored for HAT-P-16b and TOI-1516b, while the constant period model is preferred for TOI-2046b. False alarm probabilities (FAPs) were computed to assess the significance of any periodic signals. TOI-1516b displays a strong TTV signal with a FAP (of 0.0001) well below the 0.01 threshold, suggesting a likely dynamical origin that warrants further investigation. The higher FAP value (0.0055) for HAT-P-16b suggests that the case of a possible presence of an additional body in the system is less convincing. In contrast, the much higher FAP value (0.0196) for TOI-2046b implies that there are no statistically significant TTVs.

We present observational evidence for three massive, accreting black holes in the $z=5.0167$ galaxy J0148-4214 from JWST/NIRSpec-IFU spectroscopy. The black holes are revealed through broad H$\alpha$ emission (FWHM = 430-2920 km/s) without a forbidden-line counterpart in the bright [O III] doublet. Channel maps of the asymmetric central H$\alpha$ profile isolate two spatially distinct broad line regions (BLRs), separated by $190\pm40$ pc, while a third BLR is found in the galaxy outskirts with a projected separation of 1.7 kpc. Using single-epoch virial relations, we estimate black hole masses of $\log(M_\bullet/M_\odot)=7.9\pm0.4$ (primary central), $5.8\pm0.5$ (secondary central) and $6.3\pm0.5$ (third off-nuclear). We argue that the two central black holes will likely rapidly merge, with a simple dynamical friction time estimate of the order of 700 Myr. Assuming that also the off-nuclear black hole is in the process of sinking towards the centre, it will likely lead to a second merger, and we investigate the detection probability of such mergers with LISA. Alternatively, the third black hole may be the result of previous three-body interaction or a gravitational recoil, where our observations would provide evidence that such black holes may retain their accretion discs and BLRs even in the aftermath of such extreme dynamical interactions. The discovery of a black hole triplet at high redshift, together with other recent results on distant black hole pairs, indicates that multiple massive black hole systems were common in the early Universe. Our results highlight the importance of IFU observations for the detection of massive black hole multiplets in distant galaxies, the progenitors of massive black hole mergers that may be detected with next-generation gravitational wave observatories.

With JWST, observing separate spectra of the morning and evening limbs of hot Jupiters has finally become a reality. The first such observation was reported for WASP-39b, where the evening terminator was observed to have a larger transit radius by about 400 ppm and a stronger 4.3 $\mu$m CO$_2$ feature than the morning terminator. Multiple factors, including temperature differences, photo/thermochemistry, clouds and hazes, could cause such limb asymmetries. To interpret these new limb asymmetry observations, a detailed understanding of how the relevant processes affect morning and evening spectra grounded in forward models is needed. Focusing on WASP-39b, we compare simulations from five different general circulation models (GCMs), including one simulating disequilibrium thermochemistry and one with cloud radiative feedback, to the recent WASP-39b limb asymmetry observations. We also post-process the temperature structures of all simulations with a 2D photochemical model and one simulation with a cloud microphysics model. Although the temperatures predicted by the different models vary considerably, the models are remarkably consistent in their predicted morning--evening temperature differences. Several equilibrium-chemistry simulations predict strong methane features in the morning spectrum, not seen in the observations. When including disequilibrium processes, horizontal transport homogenizes methane, and these methane features disappear. However, even after including photochemistry and clouds, our models still cannot reproduce the observed ${\sim}2000$ ppm asymmetry in the CO$_2$ feature. A combination of factors, such as varying metallicity and unexplored parameters in cloud models, may explain the discrepancy, emphasizing the need for future models integrating cloud microphysics and feedback across a broader parameter space.

We use a variety of visualization techniques to display the interior and surface flows in a double white dwarf binary undergoing direct-impact mass transfer and evolving dynamically to a merger. The structure of the flow can be interpreted in terms of standard dynamical, cyclostrophic and geostrophic arguments. We describe and showcase some visualization and analysis techniques of potential interest for astrophysical hydrodynamics. In the context of R Coronae Borealis stars, we find that mixing of accretor material with donor material at the shear layer between the fast accretion belt and the slower rotating accretor body will always result in some dredge-up. We also discuss briefly some potential applications to other types of binaries.

Recent multiwavelength observations of young solar analogs suggest that the young Sun in the first 600 Myr was a magnetically active star that produced an X-ray and Extreme-UV (EUV) bright corona, fast, massive stellar wind, and energetic eruptive events. These outputs affected magnetospheric environments of early Earth and young rocky exoplanets. The interaction of the fast solar wind with the slow wind produced strong shocks from Corotating Interaction Regions (CIRs) that provided high dynamic pressure on the magnetospheres of early Venus, Earth, and Mars. Here, we apply the Space Weather Modeling Framework (SWMF), coupled with the Rice Convection Model (RCM) to simulate the response of the magnetospheric environments and associated Joule heating deposited in the upper atmosphere of early Earth as it passed through a CIR shock from the young Sun. The model suggests ~ 40% closer dayside magnetopause standoff distance, and higher negative SYMH, Cross Polar Cap Potentials (CPCP), atmospheric Joule heating, Field Aligned Currents (FAC), electron precipitations, and equatorward polar cap expansions, comparable or exceeding those of recent intense and super geomagnetic storms. The magnetic storm produces dawn-dusk asymmetries in the polar cap boundary arising from the stellar magnetic field By. The proton density enhancements during the CIR event are the dominant factor in the overall dynamic pressure for resulting electron precipitation and Joule heating deposited into the Earth's ionosphere. We discuss implications for the magnetospheric states and associated habitability conditions on early Earth and young rocky exoplanets around magnetically active solar-like stars.

The first stars formed out of pristine gas, causing them to be so massive that none are expected to have survived until today. If their direct descendants were sufficiently low-mass stars, they could exist today and would be recognizable by having the lowest metallicity (abundance of elements heavier than helium). The lowest metallicity star currently known is a star in the thick disk of the Milky Way with total metallicity Z < 1.4 x 10^-6 (log Z/Zsun < -4.0). While other stars with lower iron abundance have been discovered, they have high carbon abundances and thus higher total metallicities (log Z/Zsun > -3). Here we present the discovery and detailed chemical analysis of the most metal-poor star yet found: the red giant star SDSS J0715-7334 with ultra-low abundances of both iron and carbon ([Fe/H]=-4.3, [C/Fe]<-0.2), resulting in total metallicity Z < 7.8 x 10^-7 (log Z/Zsun < -4.3). This star has the most pristine composition of any object known in the universe. The star's orbit indicates that it originates from the halo of the Large Magellanic Cloud. Its detailed chemical composition implies a supernova progenitor with initial mass of 30 solar masses. Current models of low-mass star formation can explain the existence of SDSS J0715-7334 only if dust cooling was already able to operate at the time of its formation. SDSS J0715-7334 is over ten times more metal-poor than the most metal-poor high-redshift galaxies found by the James Webb Space Telescope, some of which have been claimed to be potentially metal-free. Substantially deeper observations of high-redshift galaxies would be needed to prove that they are truly pristine galaxies made of metal-free stars and not metal-enriched galaxies composed of second-generation stars like SDSS J0715-7334.

We present component-separated polarization maps of the cosmic microwave background (CMB) and Galactic thermal dust emission, derived using data from the BICEP/Keck experiments through the 2018 observing season and Planck. By employing a maximum-likelihood method that utilizes observing matrices, we produce unbiased maps of the CMB and dust signals. We outline the computational challenges and demonstrate an efficient implementation of the component map estimator. We show methods to compute and characterize power spectra of these maps, opening up an alternative way to infer the tensor-to-scalar ratio from our data. We compare the results of this map-based separation method with the baseline BICEP/Keck analysis. Our analysis demonstrates consistency between the two methods, finding an 84% correlation between the pipelines.

We present ARCH (Adaptive Reconstruction of Cluster Halos), a new gravitational lensing pipeline for cluster mass reconstruction that applies a joint shear-flexion analysis to JWST imaging. Previous approaches have explored joint shear+flexion reconstructions through forward modeling and Bayesian inference frameworks; in contrast, ARCH adopts a staged optimization strategy that incrementally filters and selects candidate halos rather than requiring a global likelihood model or strong priors. This design makes reconstruction computationally tractable and flexible, enabling systematic tests of multiple signal combinations within a unified framework. ARCH employs staged candidate generation, local optimization, filtering, forward selection, and global strength refinement, with a combined fit metric weighted by per-signal uncertainties. Applies to Abell 2744 and El Gordo, the pipeline recovers convergence maps and subcluster masses consistent with published weak+strong lensing results. In Abell 2744 the central core mass within 300$h^{-1}$ kpc is $2.1\times 10^{14} M_\odot h^{-1}$, while in El Gordo the northwestern and southeastern clumps are recovered at $2.6\times 10^{14} M_\odot h^{-1}$ and $2.3\times 10^{14} M_\odot h^{-1}$. Jackknife resampling indicates typical 1$\sigma$ uncertainties of $10^{12}-10^{13} M_\odot h^{-1}$, with the all signal and shear+$\mathcal{F}$ reconstructions providing the most stable results. These results demonstrate that flexion, when anchored by shear, enhances sensitivity to cluster substructure while maintaining stable cluster-scale mass recovery.

The Seyfert 1 galaxy J1626+5120 is estimated to host a $10^8 M_{\odot}$ black hole (BH) accreting at Eddington ratio $\dot{m}_{\text{Edd}} \approx 0.043$. Its long-term multi-band light curve data show flicker-like variations, but in a well-sampled $g$-band light curve, we are able to determine a $\simeq 329$\,d quasi-periodic oscillation (QPO) at a $\sim$4.53$\sigma$ significance. Six optical spectra were obtained for the source, three of which were taken by us. The spectra show that the variations were mainly because of flux changes blueward of 4000\,Å. We also analyze X-ray and ultraviolet (UV) data obtained with {\it the Neil Gehrels Swift Observatory (Swift)}, which targeted the source in the past two years. X-ray and UV emissions of the source show variations correlated with optical. Time lags of four UV bands and four optical bands are determined with respect to the X-ray emission, which are consistent with a continuum reprocessing disk model. These properties point out a disk origin for the QPO, likely due to Lense-Thirring (LT) precession of the accretion flow at $\sim$20 gravitational radii of the BH. This QPO could be a key case linking sub-year long QPOs in jets, which have more cases reported, to LT precession.

We present the first results from the ALMA Perseus Polarization Survey (ALPPS), focusing on the magnetic field in the SVS13A circumbinary disk. The dataset includes full-Stokes dust continuum observations at $\sim0\farcs3$ and 870 $\mu$m, as well as molecular line emission from C$^{17}$O$(J=3 \rightarrow 2)$ at $\sim0\farcs3$, C$^{18}$O$(J=2 \rightarrow 1)$ at $\sim0\farcs2$, and DCN$(J=3 \rightarrow 2)$ at $\sim0\farcs1$ angular resolution. Our observations resolve both a previously identified dust spiral and an infalling streamer, capturing their spatial and kinematic structures. The streamer is traced from scales $>300$ au down to the circumbinary disk. Using alignment measure (AM) maps and histograms that compare the orientations of the plane-of-sky magnetic field with local intensity and velocity gradients, we find that the AM distribution peaks at a value of 1. This AM peak strongly suggests alignment between the field and the dust total intensity emission, as well as between the field and the gas velocity, which in turn suggests grain alignment by magnetic fields. From our data, we derive a magnetic field strength, B$_{\mathrm{pos}} \sim 1.1 \pm 0.6$\, mG, and a kinetic to magnetic energy ratio of $0.5 \pm 0.4$, suggesting magnetic dominance. We also produced a map of the Alfvénic Mach number, finding $\mathcal{M}_{\rm A} < 1$ along the streamer, consistent with sub-Alfvénic infalling motions. Therefore, the field is likely facilitating the inflow of material from the envelope onto the disk by constraining movement across the field lines. This represents the first detection of a magnetically sub-Alfvénic infalling streamer in a protostellar system.

We present a substantial update to the MESA Isochrones and Stellar Tracks (MIST) library, extending the MIST model grids and isochrones down the white dwarf (WD) cooling sequence with realistic physics for WD cooling timescales. This work provides a large grid of MESA models for carbon-oxygen core WDs with hydrogen atmospheres (spectral type DA/DC), descended from full prior stellar evolution calculations. The model tracks, isochrones, and WD cooling timescale contours are available on the MIST project website and at this https URL. Our WD models provide a very large, publicly available grid with detailed physics for WD cooling timescales: realistic interior and envelope compositions, with element diffusion and heavy-element sedimentation, nuclear burning at the base of the WD hydrogen envelope, core crystallization, and C/O phase separation. As a large grid of open-source stellar evolution models, these WD models provide both out-of-the-box model tracks for comparison with observations and a framework for building further WD models to investigate variations in WD physics.

Ultra-long-period (ULP) pulsars, a newly identified class of celestial transients, offer unique insights into astrophysics, though very few have been detected to date. In radio astronomy, most time-domain detection methods cannot find these pulsars, and current image-based detection approaches still face challenges, including low sensitivity, high false positive rate, and low computational efficiency. In this article, we develop Fast Imaging Trigger (FITrig), a GPU-accelerated, statistics-based method for ULP pulsar detection and localisation. FITrig includes two complementary approaches -- an image domain and an image-frequency domain strategy. FITrig offers advantages by increasing sensitivity to faint pulsars, suppressing false positives (from noise, processing artefacts, or steady sources), and improving search efficiency in large-scale wide-field images. Compared to the state-of-the-art source finder SOFIA 2, FITrig increases the detection speed by 4.3 times for large images (50K x 50K pixels) and reduces false positives by up to 858.8 times (at 6$\sigma$ significance) for the image domain branch, while the image-frequency domain branch suppresses false positives even further. FITrig maintains the capability to detect pulsars that are 20 times fainter than surrounding steady features, even under critical Nyquist sampling conditions. In this article, the performance of FITrig is demonstrated using both real-world data (MeerKAT observations of PSR J0901-4046) and simulated datasets based on MeerKAT and SKA AA2 telescope configurations. With its real-time processing capabilities and scalability, FITrig is a promising tool for next-generation telescopes, such as the SKA, with the potential to uncover hidden ULP pulsars.

Pit craters are circular to subcircular depressions that lack a rim and ejecta layer and typically have a conical shape. There are several mechanisms that can explain the formation of such depressions and they are associated with collapse due to the removal of subsurface material. Possible origins of pit craters include: volcanic processes (collapse of lava tubes, magmatic chambers, intrusion of dikes), karstic dissolution, extensional faulting or volatile processes. Here, we propose that pit craters are stratigraphically on top of the ice-related landforms and present complex relationships with the gullies. The spatial relationship between the pits and these structures, along with the absence of evidence of present or past volcanic activity and the lack of evidence of any extensional faulting allows us to propose that the origin of the pit craters in the study area might be related to some volatile process. We propose here that these particular pit craters at Hale crater, are morphologically similar to Icelandic depressions located in a glacial environment. We conclude that the landforms found in the area are in close relation with glacial or periglacial conditions and pit craters might be formed by sublimation/melting of ground ice.

CO gas emission is a fundamental tool for measuring column density, but in cold, dark clouds, much of the CO is locked away in ice. We present JWST results from observations of a star forming filament (G0.342+0.024) that that appears to be associated with the 3 kpc arm. This filament is backlit by the Galactic Center, which has allowed us to construct a high-resolution extinction map (mean separation between stars of ~1" outside the filament, ~2" in the filament). ALMA Band 3 data reveals embedded star formation within the cloud. Using the CO ice feature covered by the F466N band, we map the CO ice column density of the filament. By combining the extinction map, CO ice column density map, and archival CO observations, we examine the efficacy of standard CO X-factor measurements of mass in star forming this http URL find that 50-88% of the CO is locked away in ice at large column densities ($N_{\rm \rm H_2} \gtrsim 10^{22} \rm ~cm^{-2}, 200 \rm ~M_{\odot} \rm ~pc^{-2}$) in the filament. The primary sources of uncertainty in this estimate are due to uncertainty in the ice composition and lab measurements of ice opacities. This shows that systematic corrections are needed for mass measurements in the Milky Way and nearby galaxies at high column densities.

Blue Large-Amplitude Pulsators (BLAPs) are a class of radially pulsating stars with effective temperatures ranging from 20,000 to 35,000 K and pulsation periods between 7 and 75 minutes. This study utilizes the Binary Population and Spectral Synthesis (BPASS) code to investigate helium-burning stars as a formation channel for BLAPs in the Milky Way. The progenitor stars have initial masses of 3-6 $M_{\odot}$, resulting in BLAPs with final masses of 0.5-1.2 $M_{\odot}$. Based on a constant star formation rate of 3 $ M_{\odot}\text{yr}^{-1}$ and solar metallicity (Z = 0.020), population synthesis predicts approximately 14,351 helium-burning BLAPs in the Milky Way: 12,799 with Main Sequence (MS) companions and 1,551 with evolved/compact-object companions. Helium-burning BLAPs show prolonged lifetimes in the pulsation region and a narrow stellar age range for entering this regime (log(t/yr) = 8.0-8.6), unlike pre-white dwarf models. BLAPs with MS companions typically form via Roche lobe overflow, leading to longer orbital periods ($\sim$100 days). Those with evolved/compact-object companions form through common envelope evolution, resulting in shorter periods. While Galactic extinction makes most BLAPs faint (apparent magnitudes $>$ 25), future surveys like WFST and VRO LSST are expected to detect approximately 500-900. This research establishes helium-burning stars as a significant BLAP contributor and offers testable predictions regarding their binary properties and Galactic distribution.

We investigate the spatial distribution, kinematics, and metallicity of stars in the Draco dwarf spheroidal galaxy using data from the Dark Energy Spectroscopic Instrument (DESI). We identify 155 high probability members of Draco using line of sight velocity and metallicity information derived from DESI spectroscopy along with {\it Gaia} DR3 proper motions. We find a mean line of sight velocity of $ -290.62\pm0.80$ km s$^{-1}$ with dispersion = $9.57^{+0.66}_{-0.62}$ km s$^{-1}$ and mean metallicity $\rm{[Fe/H]}$ = $-2.10\pm0.04$, consistent with previous results. We also find that Draco has a steep metallicity gradient within the half-light radius, and a metallicity gradient that flattens beyond the half-light radius. We identify eight high probability members outside the King tidal radius, four of which we identify for the first time. These extra-tidal stars are not preferentially aligned along the orbit of Draco. We compute an average surface brightness of 34.02 mag $\rm arcsec^{-2}$ within an elliptical annulus from the King tidal radius of 48.1 arcmin to 81 arcmin.

We study systematically the total expansion experienced by a certain perturbation mode during single-field inflation, not resorting to explicit models of inflation or reheating. By assuming that during the reheating stage the equation of state w{rh} can be written as a function of e-folds, the unknown dynamics during reheating parametrized by w{rh} is confined within a time integral so that any dependence on the models of inflation and reheating is isolated from model-independent contributions. Especially, the dependence on the reheating dynamics via w{rh} and the reheating temperature T{rh} is dominating. We give two illustrative examples of w{rh} to discuss its impacts on the total expansion, which can be different as much as 10 even for the same reheating temperature, depending on the shape of w{rh}.

In this study, we investigate how the merging process influences the radial variations of the specific Star Formation Rate (sSFR), Star Formation Efficiency (SFE), and molecular gas fraction (fmol ) in galaxies. We analyse 33 isolated galaxies and 34 galaxies in four different merger stages from pairs, merging galaxies, post-mergers, and merger remnants. Our sample is included in the EDGE-CALIFA survey, which provides spatially resolved optical integral-field unit and CO spectroscopy data. We show that, in comparison with the isolated sample, the mergers increase the molecular gas fraction non-uniformly across different galactocentric distances. Also, we find that the main driver (efficiency or molecular gas) of both enhanced and suppressed star formation changes independently of galactocentric radius and merger stage. However, efficiency appears to be the primary driver of variations in star formation (except during the merging stage), where we find an enhancement in star formation driven by the available fuel. Our results suggest that in interacting and merging galaxies, the efficiency plays a crucial role in the star formation variations throughout the galaxy, regardless of the available molecular gas content.

Active galactic nuclei (AGNs) exhibit stochastic optical variability, commonly characterized by a damped random walk. The damping timescale is of particular interest because it is related to fundamental properties of the central black hole, such as its mass and accretion rate. However, the systematic underestimation of damping timescales caused by limited observational baselines makes it difficult to exhaustively utilize all available data. Many previous efforts have relied on strict selection criteria to avoid biased measurements, and such criteria inevitably constrain the range of AGN physical parameter space and therefore hinder robust inference of the underlying dependencies of damping timescale on AGN properties. In contrast, we introduce a novel forward modeling approach, Baseline-Aware Dependence fitting for DAmping Timescales (BADDAT), which explicitly accounts for these biases and leverages the information contained in underestimated timescale measurements. Rather than attempting to correct individual timescale measurements, BADDAT robustly constrains the population-level dependence of damping timescale on AGN physical properties. We demonstrate its effectiveness using mock light curves and show that it successfully reconciles previous inconsistent results based on two independent AGN samples. Our BADDAT method will have broad applications in AGN variability studies during the era of time-domain astronomy.

The massive and bright galaxies observed by the James Webb Space Telescope (JWST) at high redshifts ($z > 6$) have challenged our understanding of the Universe. This may require revisiting the physics of galaxy formation and evolution, or modifying the $\Lambda$CDM cosmological model to explain these observations, or both. We show that high-resolution CMB experiments such as the Simons Observatory (or CMB-S4) can measure smoking-gun signatures jointly in weak lensing and kinematic Sunyaev-Zeldovich (kSZ) power spectra, which can shed light on both these scenarios. An increase in the matter power spectrum at small scales will enhance the number density of dark matter halos at high redshifts, thereby increasing the galaxy formation rate. This will cause enhanced weak lensing signal from these redshifts and also lead to enhanced patchy-kSZ signal from the epoch of reionization. However, if only galaxy astrophysics is modified, without any modification in the matter power spectrum, then the patchy-kSZ signal gets altered, while the weak lensing signal remains nearly unaltered. We show that we can measure the modified astrophysical and cosmological scenarios at a statistical significance of $6.2\sigma$ (and $17.4\sigma$) from Simons Observatory (and CMB-S4), which will enable a conclusive understanding on what physical process is driving the high-redshift observations of JWST.

We report the detection of significant $\gamma$-ray emission with $\it Fermi$-LAT from the radio-quiet Seyfert 2 galaxy NGC 3281, with a luminosity of $5.9\,(\pm 1.7)\times10^{41}\rm\,erg\,s^{-1}$ at a significance of $6.22\,\sigma$ (TS = $42.81$). The power-law photon index is $2.61~(\pm 0.24)$, indicative of a soft spectrum. The star formation activity in NGC 3281 is insufficient to explain its $\gamma$-ray luminosity based on the empirical relation between the infrared and $\gamma$-ray luminosities observed in other sources. The multiwavelength spectrum can be explained as due to inverse Compton scattering by relativistic electrons in the corona or jet of seed photons from the corona, disk and torus. The source is Compton-thick and attenuation of GeV photons due to pair production in the corona is nonnegligible (with an optical depth of about 10). The intrinsic $\gamma$-ray luminosity is inferred to be $3.4\,\times10^{42}$ and $2.2\,\times10^{41}\rm\,erg\,s^{-1}$ for the corona and jet model, respectively. The observed $\gamma$-ray and radio luminosities is roughly consistent with the known correlation between the two quantities, among the lowest luminosity regime. The jet origin is valid only if the radio emission is dominated by the jet.

HI 21-cm absorption lines are investigated to determine the origin of the neutral atomic hydrogen (HI) of the Magellanic Bridge (MB). Using the MeerKat Absorption Line Survey (MALS) data we report the detection of an HI absorption line at a peak signal-to-noise ratio of 10 caused by MB gas against the radio source J033242.97-724904.5. In combination with earlier data obtained with the Australia Telescope Compact Array (ATCA) our new detected HI line permits the exploration of the MB atomic hydrogen gas across 4-6 kpc. The radial velocity profiles from the ATCA data and new data from MALS are analysed. Apart from the excitation conditions, the radial velocity structure of the HI gas seen in emission and absorption is investigated. Eventually the gas-to-dust ratio is quantified to identify the origin of the MB gas being either from the SMC (Small Magellanic Cloud) or the LMC (Large Magellanic Cloud). The HI absorption lines towards lines of sight separated by several kpc consistently coincide with the densest and perhaps coolest gas at the lower radial-velocity limit of the corresponding HI emission profiles. The gas-to-dust ratio is found to be consistent with an origin of the MB gas from the LMC. The large scale velocity distribution as seen from the HI absorption features favors the LMC-SMC direct collision scenario over the close fly-by scenario, as also currently found by numerical simulations.

Galaxy formation and evolution is hierarchical. The most massive galaxies are thought to form their central regions early through violent dissipational processes, then grow inside-out by accreting smaller satellites. While widely supported, direct observational confirmation of this process in individual galaxies remains lacking, except for the Milky Way. We present a detailed analysis of globular cluster (GC) candidates within a $70^\prime$ ($\sim190$ kpc) radius around the nearest S0 galaxy, NGC 3115, using images in \textit{g,r,z} bands from the DESI Legacy Imaging Surveys and data from Gaia. We report the discovery of mass stratification in the GC system (GCS), evident in two ways: first, the effective radius of the GCS increases monotonically from the bright to faint end, up to the detection limit near the turnover magnitude of the GC luminosity function (GCLF); second, the GCLF shows fainter turnover magnitudes and smaller standard deviations at larger galactocentric radii. This stratification cannot be readily explained by radial migration or tidal dissolution, but most likely reflects the hierarchical assembly of NGC 3115's stellar halo, with later-accreted satellites deposited across broader galactocentric distances. This interpretation is supported by cosmological simulations of subhalos with comparable mass and bulge-to-total mass ratios and is consistent with the negative color gradients observed in the GCS. Additionally, we identify several substructures within the GCS, indicating ongoing assembly of NGC 3115. This work highlights the power of GCS as tracers of galaxy assembly and sets the stage for upcoming space-based wide-field imaging surveys to constrain the assembly of massive galaxies.

We present observations of the blazar 3C 279 at 22 GHz using the space VLBI mission RadioAstron on 2018 January 15. Images in both total intensity and fractional polarization are reconstructed using RML method implemented in the eht-imaging library. The electric vector position angles are found to be mostly aligned with the general jet direction, suggesting a predominantly toroidal magnetic field, in agreement with the presence of a helical magnetic field. Ground-space fringes were detected up to a projected baseline length of $\sim 8$G$\lambda$, achieving the angular resolution of around 26$\mu$as. The fine-scale structure of the relativistic jet is found in our study extending to a projected distance of $\sim 180$ parsec from the radio core. However, the filamentary structure reported by previous RadioAstron observations of 2014 is not detected in our current study. We discuss potential causes for this phenomenon, together with a comparison using public 43 GHz data from the BEAM-ME program, showing a significant drop in the jet's total intensity. The optically thick core is observed with a brightness temperature of $ 1.6 \times 10^{12}$ K, consistent with equipartition between the energy densities of the relativistic particles and the magnetic field. This yields an estimated magnetic field strength of 0.2 G.

Hydrogen is the most abundant element in our Universe. The first generation of stars and galaxies produced photons that ionized hydrogen gas, driving a cosmological event known as the Epoch of Reionization (EoR). The upcoming Square Kilometre Array Observatory (SKAO) will map the distribution of neutral hydrogen during this era, aiding in the study of the properties of these first-generation objects. Extracting astrophysical information will be challenging, as SKAO will produce a tremendous amount of data where the hydrogen signal will be contaminated with undesired foreground contamination and instrumental systematics. To address this, we develop the latest deep learning techniques to extract information from the 2D power spectra of the hydrogen signal expected from SKAO. We apply a series of neural network models to these measurements and quantify their ability to predict the history of cosmic hydrogen reionization, which is connected to the increasing number and efficiency of early photon sources. We show that the study of the early Universe benefits from modern deep learning technology. In particular, we demonstrate that dedicated machine learning algorithms can achieve more than a $0.95$ $R^2$ score on average in recovering the reionization history. This enables accurate and precise cosmological and astrophysical inference of structure formation in the early Universe.

We presented the optimization procedures of the baffle mounted on the GroundBIRD telescope for measuring the polarization of the Cosmic Microwave Background~(CMB). The telescope employs dual mirror reflective telescopes installed in a cryostat. The primary objectives were to minimize stray light contamination, maintain the integrity of the main beam, and ensure that thermal loading from the baffle remains significantly below that from the atmosphere. Using quasi-optical simulations, we have optimized the baffle's aperture angle to suppress stray light without degrading the main beam quality. We confirmed through Moon observations that the optimized baffle design works to eliminate the contamination of the stray light as expected. Furthermore, no measurable degradation in the noise equivalent temperature~(NET) was detected, indicating minimal thermal impact. These results show that our baffle optimization strategy effectively reduces systematic errors while maintaining observational sensitivity, providing valuable insights for future CMB experiments with similar optical architectures.

The MAGIC and LST-1 telescopes, located at the Roque de los Muchachos Observatory on La Palma, operate dedicated On-Site Analysis (OSA) pipelines that provide rapid, automated processing of observational data. These systems produce high-level data products just a few hours after observations are completed, enabling quick-look analyses, next-day data quality assessments, and rapid-response science such as flare detection and Target of Opportunity follow-ups. OSA pipelines have been in continuous operation since 2012 for MAGIC and since 2021 for LST-1, automatically processing nightly data using the standard analysis chain. The experience gained from both systems provides essential lessons for the development of Cherenkov Telescope Array Observatory's (CTAO's) on-site analysis, demonstrating the practical and scientific benefits of fast data processing in Cherenkov telescopes.

Recent discoveries made with JWST observations include a significant number of barred galaxies at high redshift. Their origin remains unclear and their presence seems difficult to reproduce in cosmological simulations of galaxy formation and evolution. In this Letter I present four examples of high-redshift bars selected from a sample of bar-like galaxies studied previously using IllustrisTNG simulations. All the galaxies formed their bars at redshifts z > 3 via mergers with smaller satellites, although one had its bar formed even earlier, at z > 5. The bars were born long, with lengths on the order of 3 kpc, and grew in time. Three of the four galaxies were later accreted by clusters and underwent multiple interactions with their respective brightest cluster galaxies. Their bar strength was to some extent affected by these interactions but all the galaxies preserved their bar-like shape until the present time. By the end of the evolution, all the galaxies lost their gas and stopped forming stars, they retained essentially no disk component and were no longer rotationally supported. The examples demonstrate that high-z bars do not evolve into present-day barred disk galaxies similar to the Milky Way but rather into S0s or ellipticals typically found in galaxy clusters.

The temperature and polarization of the cosmic microwave background (CMB), as measured today, may offer key insights into the topology of the early universe prior to inflation, for example, by discriminating between flat and warped geometries. In this paper, we focus on a Kaluza-Klein model with an extra spatial dimension that compactifies at the Grand Unified Theory (GUT) epoch, subject to mixed Neumann/Dirichlet boundary conditions at fixed points. As a consequence, a set of infrared cutoffs naturally emerges in both the scalar and tensor spectra, leading to observable consequences in the CMB. We examine in detail the possible signatures of such a topology, particularly in relation to the even-odd parity imbalance already reported by the COBE, WMAP and Planck missions in the temperature angular correlations at large scales. Furthermore, we extend our analysis to the existing Planck E-mode polarization data, and to the high-precision B-mode polarization measurements expected from the forthcoming LiteBIRD mission.

We present an independent spectroscopic and radial velocity analysis for nine stars from the Pennsylvania-Toruń Planet Search. For BD+24 4697, we present an updated true companion's mass (0.16$\pm$0.02 \, M$_{\odot}$), as well as evidence of stellar activity. For BD+54 1640 and BD+65 1241 we present true masses of companions, $m = 0.15 \pm 0.04\,M_\odot$ and $m = 0.091 \pm 0.005\,M_\odot$, respectively. For BD+63 974 and BD+69 935 we find low mass companions with $m \sin i = 0.046 \pm 0.001\,M_\odot$ and $m \sin i = 0.090 \pm 0.005\,M_\odot$. For BD+52 1281, BD+54 1382, TYC 2704-2680-1, and TYC 3525-02043-1 we present evidence of low-mass companions with $m \sin i$ of 0.115 $\pm 0.006\,M_\odot$, 0.083 $\pm 0.007\,M_\odot$, 0.279 $\pm 0.009\,M_\odot$, and $0.064 \pm 0.006\,M_\odot$, respectively. Consequently, BD+54 1382, BD+63 974, BD+65 1241, BD+69 935 and TYC 3525-02043-1 appear to be Brown Dwarf host candidates.

We investigate the expected accuracy of redshifts that can be obtained using low-resolution spectroscopic (medium-band) data from the 7-Dimensional Sky Survey (7DS). By leveraging 40 densely sampled filters with widths of full width at half maximum (FWHM) = 25 nm, we create 7DS mock catalogs and estimate the redshift accuracy for three 7DS main surveys: Wide-field Time-Domain Survey (WTS), Intensive Monitoring Survey (IMS), and Reference Image Survey (RIS). Using photometric redshifts calculated from EAZY, we find that the five-year WTS provides reliable photometric redshifts with an normalized median absolute deviation (${\sigma}_{\text{NMAD}}$) ranging from 0.003 to 0.007 and a catastrophic failure fraction ({\eta}) from 0.8% to 8.1% at $19 \leq m_{625}$ < 22$. The spectral resolution R ~ 50 of the medium-band dataset effectively captures the 4000 Å break and various emission lines. We also explore the synergy with data obtained from Pan-STARRS1, VIKING, and SPHEREx surveys. Combining the SPHEREx all-sky data with WTS significantly improves the accuracy of photometric redshift estimates, achieving {\eta} = 0.4% and ${\sigma}_{\text{NMAD}}$ = 0.004 for fainter sources at higher redshifts. The additional near-IR information provided by SPHEREx and VIKING plays an essential role in resolving degeneracies between low and high redshifts. We also observe color excesses by subtracting adjacent broad-band data, which improves the confinement of photometric redshifts and aids in the detection of strong emission line galaxies.

It is anticipated that the faint 21 cm signal emitted by neutral hydrogen within cosmic filaments can be detected. However, because of the signal's weakness, stacking techniques are necessary. We assessed two stacking methods--pair stacking and filament stacking--using the EAGLE and IllustrisTNG simulations. Pair stacking leverages the fact that cosmic filaments serve as the connectors between cosmic web nodes, while filament stacking directly aggregates cosmic filaments identified by galaxy distributions. Our analysis indicates that, although pair stacking is convenient, it faces contamination from massive structures, the signal from filament gets very weak after the contamination is removed. Conversely, HI detection via filament stacking appears more viable. The column density exceeds $10^{17} \,{\rm cm}^{-2}$ even when all halos are masked, and it is nearly 10 times higher than what is achieved with pair stacking. The effectiveness of filament stacking could further increase with a high number density galaxy catalog and better spatial resolution in radio observation intensity mapping. With the advent of new optical and radio data, the future detection of HI filaments looks promising.

Context. Recent Monte Carlo simulations and laboratory studies of interstellar ices have proposed an alternative pathway involving the radical-molecule H-atom abstraction reaction in the overall mechanism of methanol (CH3OH) formation in dark molecular clouds. Aims. A computational study was conducted to investigate the contribution of the radical-molecule H-atom abstraction route in CH3OH formation in interstellar ices, both in non-shocked and shocked environments, and to examine how the physical conditions of the interstellar medium (ISM) affect the overall CH3OH synthesis pathway. Methods. A set of chemical models were ran using the gas-grain chemical code UCLCHEM to systematically explore methanol synthesis in various physical scenarios, including non-shock and low- and high-velocity C-shocks. Results. This work demonstrated for the first time that, under non-shock and shocked-influenced environments, the primary reaction leading to the formation of methanol in the inner layers of interstellar ices is indeed the radical-molecule H-atom abstraction route. However, such route is dependent on the gas kinetic temperature (Tk), gas volume density (nH2 ), velocity of the C-shock wave (vshock), and cosmic ray ionisation rate ({\zeta}). Furthermore, gaseous formaldehyde may trace C-type shocks and serve to differentiate methanol formation pathways in low-velocity C-shocked environments, as its abundance varies more significantly than that of CH3OH with the inclusion of the H-atom abstraction reaction in UCLCHEM. The H2CO/CH3OH ratio thus represents a potential diagnostic tool for this purpose.

We present the first measurement of the cross-correlation between anisotropic birefringence and galaxy number counts, utilizing polarization data from Planck NPIPE and the Quaia quasar catalog. By employing a QML/pseudo-$C_\ell$ combined estimator, we compute the angular power spectrum up to $\ell=191$ from birefringence and clustering maps at $N_{\rm side}=64$. Our analysis indicates that the observed spectrum is well consistent with the null-hypothesis, with a probability to exceed of 37% and an estimated scale-invariant amplitude of $A^{\mathcal{D}_\ell}=(2.22\pm2.09)\times10^{-4}\,\text{deg}$, at the 68% confidence level. Finally, we derive constraints on the axion-parameters within an early dark energy model of birefringence. Our findings reveal an unprecedented upper bound on the axion-photon coupling down to $g_{\phi\gamma}=10^{-15}\,\text{GeV}^{-1}$ for masses around $10^{-32}\,\text{eV}$ and high initial misalignment angles. This result opens a previously unexplored window in parameter space, providing the first constraint in this ultra-light mass regime.

A star's luminosity increases as it evolves along the Main Sequence (MS), which inevitably results in a higher surface temperature for planets in orbit around the star. Technologically advanced civilizations may tackle this issue by installing artificial structures -- starshades -- which can reduce the radiation received by the planet. Starshades, if they exist, are potentially detectable with current or near-future technology. We have simulated phase curve signatures in direct imaging of hypothetical starshades in systems targeted by the upcoming Habitable Worlds Observatory (HWO), which will be tasked with searching for Earth-like exoplanets orbiting nearby stars. The starshade is assumed to be a circular, reflecting surface placed at the inner Lagrange point between the star and the planet. Our results show that the phase curve of a starshade has a distinct shape compared to that of a typical planet. The phase curve signature lies above the expected $1\sigma=10^{-11}$ single-visit precision in contrast ratio of the telescope for 70.8% of the target stars for the expected inner working angle (IWA) of around 60 mas. If the IWA can be reduced to 45 mas, the percentage of stars above the $1\sigma$ limit increases to 96.7%. With a sufficiently small IWA, HWO should be able to detect anomalies in light curves caused by starshades or similar highly-reflective surfaces -- which could serve as key indicators for technologically advanced civilizations.

This study presents an analysis of cosmological parameters, focusing on resolving the Hubble tension and constraining neutrino masses within a coupled quintom model. By utilizing datasets from the Cosmic Microwave Background (CMB), Pantheon + Analysis, Cosmic Chronometers (CC), Baryon Acoustic Oscillations (BAO), and CMB Lensing, we explore the interplay between cosmological parameters and observational constraints. The model effectively reduces the Hubble tension, achieving a consistency in $H_0$ measurements of $1.37\sigma$ and $1.24\sigma$ for the CMB + ALL dataset For Planck 2018 and R22 respectively. Additionally, the study refines constraints on the total mass of neutrinos ($\Sigma_{m_{\nu}}$), with a finding of $0.115\,\text{eV}$ for the CMB + ALL dataset. The analysis examines the effective equation of state parameter ($w_{\text{eff}}$), indicating a transition towards a universe dominated by exotic energy forms. The combined datasets refine $w_{\text{eff}}$ to $-1.02\pm0.018$, underscoring the importance of multi-dataset integration in understanding dark energy dynamics. Furthermore, the interaction constant $\beta$ between the quintom scalar field and neutrinos is constrained to $0.65 \pm 0.12$ for the CMB + ALL dataset. The potential parameters $\lambda_{\sigma} = -2.09 \pm 0.082$ and $\lambda_{\phi} = 2.43 \pm 0.12$ are also determined, providing insights into the quintom model's implications for cosmological dynamics. This study offers compelling evidence for the coupled quintom model's capability to resolve the Hubble tension and refine constraints on neutrino properties, enhancing our understanding of the universe's evolution.

We present morphological classifications of over 41,000 galaxies out to $z_{\rm phot}\sim2.5$ across six square degrees of the Euclid Deep Field North (EDFN) from the Hawaii Twenty Square Degree (H20) survey, a part of the wider Cosmic Dawn survey. Galaxy Zoo citizen scientists play a crucial role in the examination of large astronomical data sets through crowdsourced data mining of extragalactic imaging. This iteration, Galaxy Zoo: Cosmic Dawn (GZCD), saw tens of thousands of volunteers and the deep learning foundation model Zoobot collectively classify objects in ultra-deep multiband Hyper Suprime-Cam (HSC) imaging down to a depth of $m_{HSC-i} = 21.5$. Here, we present the details and general analysis of this iteration, including the use of Zoobot in an active learning cycle to improve both model performance and volunteer experience, as well as the discovery of 51 new gravitational lenses in the EDFN. We also announce the public data release of the classifications for over 45,000 subjects, including more than 41,000 galaxies (median $z_{\rm phot}$ of $0.42\pm0.23$), along with their associated image cutouts. This data set provides a valuable opportunity for follow-up imaging of objects in the EDFN as well as acting as a truth set for training deep learning models for application to ground-based surveys like that of the newly operational Vera C. Rubin Observatory.

Icy moons orbiting giant planets are often described as airless bodies though they host an exosphere where collisions between neutral species are scarce. In the case of Ganymede, the neutral composition is dominated by $\mathrm{H_2O}$, $\mathrm{H_2}$, and $\mathrm{O_2}$. Past observations by Galileo showed that Ganymede hosts an ionosphere and those by Juno revealed the presence of $\mathrm{H_3^+}$, an ion species only stemming from ion-neutral collisions. $\mathrm{H_3^+}$ detection suggests that ions and neutrals might still collide and be the source of new ion species on icy moons. We examine Ganymede's ability to host a more diverse ionosphere in terms of ion composition than previously thought and predict its variety. We upgraded our test-particle code of Ganymede's ionosphere, formerly collisionless, to include ion-neutral collisions in a probabilistic manner. The updated code is applied to three Galileo flybys of Ganymede that were investigated in the absence of chemistry. Both sets of simulations have been compared and the effect of ion-neutral chemistry has been assessed. We show that in the case of an exosphere predominantly composed of $\mathrm{H_2O}$, $\mathrm{H_2}$, and $\mathrm{O_2}$, the ionosphere is made not only of their associated cations but also of $\mathrm{H_3^+}$, $\mathrm{H_3O^+}$, and $\mathrm{O_2H^+}$. Simulations reveal that, depending on the location, the contribution of $\mathrm{H_3^+}$ and $\mathrm{H_3O^+}$ to the ion composition may be significant. Strong dayside/nightside and Jovian/anti-Jovian asymmetries in the ion composition are identified. Our findings are key to interpreting Juno and future JUICE ion mass spectrometer datasets.

We introduce N+2 mapmaking as a novel approach to constructing maps in both intensity and polarization for multi-detector CMB data. The motivation behind this method is two-fold: Firstly, it provides individual temperature detector maps from a multi-detector set, which may be useful for component separation purposes, in particular for line emission reconstruction. Secondly, it simultaneously outputs coadded polarization maps with minimal temperature-to-polarization leakage sensitivity. Algorithmically speaking, the N+2 mapmaker is closely related to the `spurious mapmaking' algorithm pioneered by the WMAP team, but rather than solving for a spurious S map together with the three normal Stokes IQU parameters, we solve for N temperature maps and two Stokes (Q and U) parameters per pixel. The result is a statistically coherent set of physically meaningful per-detector temperature maps, each with slightly different bandpasses as defined by each detector, combined with coadded polarization maps. We test this approach on Planck Low Frequency Instrument (LFI) 30 GHz data, and find that the Planck scanning strategy is too poorly cross-linked to allow for a clean separation between temperature and polarization. However, noting that pairs of detectors within a single horn are strongly anti-correlated, we anticipate that solving for horn maps, as opposed to individual detector maps, may provide an optimal compromise between noise and temperature-to-polarization leakage minimization. When applied to simulated data with a rotating half-wave plate, for which the polarization angle coverage is greatly improved, the algorithm performs as expected.

RR Lyrae stars have long been considered unequivocal tracers of old (>10 Gyr) and metal-poor ($\mathrm{[Fe/H]}<-0.5$) stellar populations. First, because these populations are where they are readily found and because, according to canonical stellar evolution models for isolated stars, these are the only populations where RR Lyrae should exist. Recent independent results, however, are challenging this view and pointing at the existence of intermediate-age RR Lyrae, only a few (2--5) Gyrs old. Our goal in this work is to provide direct evidence of the existence of intermediate-age RR Lyrae by searching for these stars in Milky Way open clusters, where the age association will be direct and robust. We searched over 3,000 open clusters with published kinematically associated member stars from the Hunt & Reffert database by crossmatching against a compilation of the largest publicly available RR Lyrae surveys (\Gaia, ASAS-SN, PanStarrs1, Zwicky Transient Factory and OGLE-IV). We identified a star as a bona fide RR~Lyrae variable and robust member of the 2--4 Gyr old Trumpler 5 cluster, based on its parallax and proper motions and their agreement with confirmed cluster members. We derived an extremely low probability ($0.049\pm 0.013$%) that the star is a background field RR~Lyrae and provide initial constraints on a possible binary companion based on its position in the colour-absolute magnitude diagram. Currently a source of debate, the Trumpler~5 RR Lyrae provides the most direct evidence to date of the existence of RR Lyrae stars at much younger ages than traditionally expected and adds to the mounting evidence supporting their existence.

Axion-like particles (ALPs) are compelling candidates for dark matter and potential portals to new physics beyond the Standard Model. Photons traversing magnetized regions can convert into ALPs, producing characteristic, energy-dependent absorption features in astrophysical spectra. The probability of such conversions depends sensitively on both the photon energy and the properties of the intervening magnetic fields. Most existing searches have focused on individual astrophysical sources, but uncertainties in the structure and strength of cosmic magnetic fields have limited their reach. Recently, we have demonstrated that active galactic nuclei (AGNs) observed through galaxy clusters provide especially promising targets for ALP searches. By stacking multiple AGN-cluster sightlines, one can average over poorly known magnetic field configurations in galaxy clusters and recover a distinctive ALP-induced spectral suppression, thereby significantly enhancing sensitivity. In this work, we investigate a possible systematic uncertainty in such analyses: the intrinsic time-variability of AGN spectra. We demonstrate that AGN flux variability is correlated with spectral hardness, and that time-averaging over flaring and quiescent states can potentially mimic the suppression features imprinted by ALP-photon mixing. Our findings imply that the recent constraints remain conservative, and that incorporating detailed spectral variability into stacking analyses can further sharpen the search for axion-like particles.

Polycyclic Aromatic Hydrocarbons (PAHs) are organic molecules responsible for the Aromatic Infrared Bands (AIBs), observed across a multitude of astrophysical environments. Despite their ubiquity, the precise formation mechanisms of PAHs remain unclear. One of the possible way for PAHs to form is in the outflows of evolved stars, such as HD 44179, which produces the Red Rectangle nebula - a known emitter of AIBs. However, no specific PAH molecules have been detected in such environments, complicating the understanding of PAH formation and evolution. This study aimed to detect the PAH molecule corannulene C20H10, a viable candidate for radio detection due to its large dipole moment of 2.07D. We analyzed high-resolution band 4 ALMA observations of the Red Rectangle nebula, collected over almost 9 hrs. Although corannulene emission was not detected, we estimated a firm upper limit on its abundance compared to hydrogen (5x10^-13) and we discuss the lack of detection in the context of our current understanding of PAH formation and destruction mechanisms. Additionally, we report tentative detection of signals at 139.612 GHz, 139.617 GHz, and 139.621 GHz, potentially originating from cyclopropenyledine c-C3H2 and the 140 GHz H2O maser.

The death of massive stars is accompanied by the formation of central and accreting compact objects and the subsequent launch of relativistic jets. However, not all jets successfully drill their way out of the stellar envelope. Unsuccessful jets, also known as choked jets, may still produce radiation at lower frequencies by dissipating the jet energy into a pressurized cocoon. This cocoon expands within the stellar envelope and eventually breaks out as a mildly relativistic outflow. We investigate the plasma physics in the surroundings of massive collapsing stars harboring choked jets via relativistic, non-resistive MHD simulations. As a result, we define the parameter space allowing for jets to remain choked, and we quantify the acceleration rate and efficiency for charged particles in the strong shocks of such astrophysical environments. Preliminary results show that high Mach numbers ($\sim 100$) after 5-10 seconds of constant energy injection characterize the forward shock, possibly allowing for efficient particle acceleration and high-energy neutrino production. Our results are presented for blue supergiant progenitors.

The "Diamond Ring" in Cygnus X, southwest of the DR21 ridge, is a nearly circular structure of $\sim$6 pc in diameter, prominent in FIR emission and enclosed by clumpy molecular clouds traced in CO. It hosts an HII region, visible in cm emission, and resembles a classical expanding HII bubble routinely seen in the 158 $\mu$m [CII] line. However, SOFIA FEEDBACK observations in the spectrally resolved [CII] line reveal instead a slightly tilted ring of $\sim$10$^3$ M$_\odot$ expanding slowly at $\sim$1.3 km s$^{-1}$, with a bulk line-of-sight (LOS) velocity near $-2$ km s$^{-1}$. The central "Diamond" is an unrelated dense clump at $\sim$7 km s$^{-1}$. The driving source, classified from IR spectroscopy, is a B0.5e star that powers the HII region. Unlike typical 3D shells, this marks the first case where we detect only a slowly expanding CII ring. We suggest the HII region and CII bubble, initially formed by a massive star, expanded outward from a flat slab of molecular gas nearly in the plane of the sky. The ring is now confined by swept-up material of the slab, while shell components moving perpendicular to the LOS have dissipated, leading to a reduction in expansion. Dedicated simulations tracing the evolution of the CII bubble support this geometry, consistent with previous reports of HII region evolution in flat molecular clouds. We propose that the "Diamond Ring" represents the terminal phase of an expanding CII bubble driven by stellar winds and thermal pressure.

We present Hyper-Py, a fully restructured and extended Python implementation of HYPER (HYbrid Photometry and Extraction Routine, Traficante et al. 2015). HYPER was originally implemented in IDL, aiming to deliver robust and reproducible photometry of compact sources in FIR/sub-mm/mm maps. HYPER combines source detection via high-pass filtering, background estimation through local polynomial fitting, and source modeling with 2D elliptical Gaussians, simultaneously fitting multiple Gaussians to deblend overlapping sources. Hyper-Py preserves the original logic while offering improvements in performance, configurability, and background modeling capabilities, making it a flexible modern tool for source extraction and photometry across diverse datasets. Notably, Hyper-Py enables background estimation and subtraction across individual slices of 3D datacubes, allowing consistent background modeling along the spectral axis for line or continuum studies in spectrally resolved observations.

Dark matter halos are fundamental structures in cosmology, forming the gravitational potential wells hosting galaxies and clusters of galaxies. Their properties and statistical distribution (including the halo mass function) are invaluable tools to infer the fundamental properties of the Universe. The \texttt{halox} package is a JAX-powered Python library enabling differentiable and accelerated computations of key properties of dark matter halos, and of the halo mass function. The automatic differentiation capabilities of \texttt{halox} enable its usage in gradient-based workflows, e.g. in efficient Hamiltonian Monte Carlo sampling or machine learning applications.

SDSS-C4 3028 is a galaxy cluster at $z=0.061$, notable for its unusually high fraction of star-forming galaxies with 19 star-forming and 11 quiescent spectroscopically-confirmed member galaxies. From Subaru/HSC imaging, we derived a weak lensing mass of $M_{200} = (1.3 \pm 0.9) \times 10^{14} \rm M_\odot$, indicating a low-mass cluster. This is in excellent agreement with its dynamical mass of $M_{200} = (1.0\pm0.4)\times10^{14} \rm M_\odot$, derived from SDSS spectroscopic data. XMM-Newton observations reveal that its X-ray emission is uniform and fully consistent with the astrophysical X-ray background, with no evidence for an intracluster medium (ICM). The 3$\sigma$ upper limit of $L_{\rm X}(0.1-2.4\rm keV)=7.7\times10^{42}$ erg s$^{-1}$ on the cluster's X-ray luminosity falls below the value expected from the $L_{\rm X}-M_{\rm halo}$ scaling relation of nearby galaxy clusters. We derived star-formation histories for its member galaxies using the photometric spectral energy distribution from SDSS, 2MASS, and WISE data. Most of its quiescent galaxies reside within the central 300 kpc, while star-forming ones dominate the outer region (300 kpc - 1 Mpc). The core region has formed the bulk of its stellar mass approximately 1.5 Gyr earlier than the outskirts. We infer a long quenching time of $>3$ Gyr for its quiescent galaxies, consistent with slow quenching mechanisms such as galaxy-galaxy interaction or strangulation. These findings suggest that SDSS-C4 3028 may have undergone an "inside-out" formation and quenching process. Its ICM may have been expelled by intense AGN feedback after core formation but before full cluster assembly. The high fraction ($\sim$0.63) of star-forming members likely results from the absence of ram pressure stripping in this blue cluster, supporting the important role of ram pressure stripping in quenching galaxies in clusters.

Small bodies exist in distinct populations within their planetary systems. These reservoir populations hold a range of compositions, which to first order are dependent on formation location relative to their star. We provide a general overview of the nature of the reservoirs that source exocomets, from the influence of the stellar environment through planetesimal formation to comparisons with Solar System populations. Once transitioned from a young protoplanetary disc to a debris disc, a star can expect to be rained with exocomets. While exocomets are predominantly detected to date at A-type stars, planetesimals plausibly exist across a range of stellar masses, based on exoplanet abundance, debris disc occurrence and white dwarf infall.

The Taurid Resonant Swarm (TRS) within the Taurid Complex hosts dynamically-concentrated debris in a 7:2 mean-motion resonance with Jupiter. Fireball observations have confirmed that the TRS is rich in sub-meter-sized particles, but whether this enhancement extends to larger, asteroid-sized objects remains unclear. Here we reanalyze the data obtained by a Zwicky Transient Facility (ZTF) campaign during the 2022 TRS encounter, and find that the TRS may host up to $\sim10^2$ Tunguska-sized objects and up to $\sim10^3$ Chelyabinsk-sized objects, the latter of which agrees the estimate derived from bolide records. This translates to an impact frequency of less than once every 4 million years. However, we caution that these numbers are based on the unverified assumption that the orbital distribution of the TRS asteroids follows that of fireball-sized meteoroids. Future wide-field facilities, such as the Vera C. Rubin Observatory, could take advantage of TRS's close approaches in the 2020-30s and validate the constraints of the asteroid-sized objects in the TRS.

We used the third data release of the UKIRT Hemisphere Survey to locate previously unrecognized high proper motion objects. We identify a total of 127 new discoveries with total proper motions $\gtrsim$300 mas yr$^{-1}$. A significant fraction of these sources with counterparts in the Gaia DR3 catalog are found to be distant ($>$100 pc) low-mass stars, where their large tangential velocities and placement on color-magnitude diagrams suggest that they are likely low-metallicity M-type subdwarfs. Optical spectroscopy is used to confirm the low-mass and low-metallicity for two such sources. Using available optical and infrared photometry, we estimate the spectral type for all non-Gaia sources and find 10 likely late-M dwarfs, 15 objects with colors most consistent with L-type dwarfs, and 9 possible T-type dwarfs. Follow-up spectroscopy is needed to confirm spectral types and further characterize these new discoveries.

The search for dark matter has been ongoing for decades within both astrophysics and particle physics. Both fields have employed different approaches and conceived a variety of methods for constraining the properties of dark matter, but have done so in relative isolation of one another. From an astronomer's perspective, it can be challenging to interpret the results of dark matter particle physics experiments and how these results apply to astrophysical scales. Over the past few years, the ESCAPE Dark Matter Test Science Project has been developing tools to aid the particle physics community in constraining dark matter properties; however, ESCAPE itself also aims to foster collaborations between research disciplines. This is especially important in the search for dark matter, as while particle physics is concerned with detecting the particles themselves, all of the evidence for its existence lies solely within astrophysics and cosmology. Here, we present a short review of the progress made by the Dark Matter Test Science Project and their applications to existing experiments, with a view towards how this project can foster complementary with astrophysical observations.

Understanding the asymptotic behaviour of numerical dynamo models is critical for extrapolating results to the physical conditions that characterise terrestrial planetary cores. Here we investigate the behaviour of convection-driven dynamos reaching a MAC (magnetic-Archimedes-Coriolis) balance on the convective length scale and compare the results with non-magnetic convection cases. In particular, the dependence of physical quantities on the Ekman number, $Ek$, is studied in detail. The scaling of velocity dependent quantities is observed to be independent of the force balance and in agreement with quasi-geostrophic theory. The primary difference between dynamo and non-magnetic cases is that the fluctuating temperature is order unity in the former such that the buoyancy force scales with the Coriolis force. The MAC state yields a scaling for the flow speeds that is identical to the so-called CIA (Coriolis-inertia-Archimedes) scaling. There is an $O(Ek^{1/3})$ length scale present within the velocity field irrespective of the leading order force balance. This length scale is consistent with the asymptotic scaling of the terms of the governing equations and is not an indication that viscosity plays a dominant role. The peak of the kinetic energy spectrum and the ohmic dissipation length scale both exhibit an Ekman number dependence of approximately $Ek^{1/6}$, which is consistent with a scaling of $Rm^{-1/2}$, where $Rm$ is the magnetic Reynolds number. For the dynamos, advection remains comparable to, and scales similarly with, both inertia and viscosity, implying that nonlinear convective Rossby waves play an important role in the dynamics even in a MAC regime.

We introduce \textit{SeismoGPT}, a transformer-based model for forecasting three-component seismic waveforms in the context of future gravitational wave detectors like the Einstein Telescope. The model is trained in an autoregressive setting and can operate on both single-station and array-based inputs. By learning temporal and spatial dependencies directly from waveform data, SeismoGPT captures realistic ground motion patterns and provides accurate short-term forecasts. Our results show that the model performs well within the immediate prediction window and gradually degrades further ahead, as expected in autoregressive systems. This approach lays the groundwork for data-driven seismic forecasting that could support Newtonian noise mitigation and real-time observatory control.

Plasmas in various astrophysical systems are in non-equilibrium states as evidenced by direct in-situ measurements in the solar wind, solar corona and planetary environments as well as by indirect observations of various sources of waves and emissions. Specific are non-Maxwellian velocity distributions with suprathermal tails, for whose description the most-used are the Kappa (power-law) distributions. With this paper we introduce a modeling alternative for linear waves in plasmas described by another non-equilibrium model, namely the generalized Druyvesteyn distribution. This can reproduce not only the high-energy tails, but also the low-energy flat-tops of velocity distributions, like those of electrons associated with the Earth's bow shock and interplanetary shocks or of electrons in the solar transition region. We derive the corresponding dispersion relation for longitudinal waves in terms of the newly introduced Druyvsteyn dispersion function, numerically compute, for the isotropic case, the dispersion curves as well as damping rates, and provide analytical approximation in the limit of weak damping. Thereby, we provide a new modeling tool that facilitates the quantitative treatment of a variety of non-Maxwellian plasmas.

Numerical relativity has produced wide-ranging influences on modern astrophysics and gravitational-wave astronomy. In this work, we develop a Python interface for the numerical relativity program AMSS-NCKU, which enables the automation of initializing and starting the AMSS-NCKU simulations and the automatically generating visualizations of the output results. Numerical relativity simulations using this Python interface have been presented through two representative examples (binary back hole and triple black hole merger processes), and well-behaved stable numerical results and the expected physical behaviors for black hole systems have been acquired. The Python operational interface significantly lowers the operational complexity of the simulation workflow of AMSS-NCKU simulations, reducing the technical barriers for freshman users.

The development of novel instrumentation requires an iterative cycle with three stages: design, prototyping, and testing. Recent advancements in simulation and nanofabrication techniques have significantly accelerated the design and prototyping phases. Nonetheless, detector characterization continues to be a major bottleneck in device development. During the testing phase, a significant time investment is required to characterize the device in different operating conditions and find optimal operating parameters. The total effort spent on characterization and parameter optimization can occupy a year or more of an expert's time. In this work, we present a novel technique for automated sensor calibration that aims to accelerate the testing stage of the development cycle. This technique leverages closed-loop Bayesian optimization (BO), using real-time measurements to guide parameter selection and identify optimal operating states. We demonstrate the method with a novel low-noise CCD, showing that the machine learning-driven tool can efficiently characterize and optimize operation of the sensor in a couple of days without supervision of a device expert.

The magnetic monopole of a dark sector has been advocated as an appealing dark matter candidate. We revisit the computation of the monopole abundance $\Omega_M$, generated by a thermal phase transition in the minimal 't Hooft-Polyakov model. We explore the three regimes where the phase transition is second order, weakly first order, or supercooled, identifying the parameter space regions where $\Omega_M$ can match the observed dark matter abundance. However, the dark sector necessarily contains a stable electrically-charged particle, namely a massive vector boson, with a calculable abundance $\Omega_{W'}$. We show that, under minimal assumptions, $\Omega_{W'}$ is always far larger than $\Omega_M$: dark monopoles cannot constitute a sizeable fraction of dark matter.

The dark matter observation claimed by the DAMA/LIBRA experiment has been a long-standing puzzle within the particle physics community. NaI(Tl) crystals with radiopurity comparable to DAMA/LIBRA's are essential for adequate verification. Existing experiments using NaI(Tl) target have been hampered by the high radioactivity concentration of NaI(Tl) crystals. PICOLON experiment conducts an independent search for Weakly Interacting Massive Particles using highest purity NaI(Tl) crystals. In 2020, the NaI(Tl) crystal (Ingot#85) reached the same purity level as DAMA/LIBRA crystals. The DAMA/LIBRA group has stressed that verifying their signal requires high-purity NaI(Tl) crystals with long-term stability. Based on a six-month measurement, we have confirmed the long-term stability of its radiopurity. This stability provides a significant advantage for future efforts to adequately verify the DAMA/LIBRA result using NaI(Tl) crystal. In this paper, we present the background stability of purity in the Ingot#94 NaI(Tl) detector, which was produced using the Ingot#85 purification method, along with the first annual modulation search conducted by the PICOLON experiment.

We use stellar dynamics as a testbed for statistical closure theory. We focus on the process of "Vector Resonant Relaxation," a long-range, non-linear, and correlated relaxation mechanism that drives the reorientation of stellar orbital planes around a supermassive black hole. This process provides a natural setting to evaluate the predictive power of generic statistical closure schemes for dynamical correlation functions, in the fully non-linear and non-perturbative regime. We develop a numerical scheme that explicitly implements the seminal "Martin-Siggia-Rose" formalism at one-loop order via an iterative fixed-point approach, thereby improving upon the bare order from the "Direct Interaction Approximation." Using this framework, we quantitatively validate the ability of the formalism to predict (i) the two-point two-time correlation function; (ii) the renormalised three-point interaction vertex; (iii) the three-point three-time correlation function. These predictions are compared to direct measurements from numerical simulations. We conclude by discussing the limitations of this approach and presenting possible future venues.

Direct detection dark matter experiments have proven to be compelling probes for studying low-energy neutrino interactions with both nuclei and atomic electrons, offering complementary information to accelerator and reactor-based neutrino experiments. Recently, the XENONnT and PandaX-4T collaborations reported the first evidence of coherent elastic neutrino-nucleus scattering from $^8\mathrm{B}$ solar neutrinos. Thanks to their excellent background rejection capabilities and distinctive signal signatures, dual-phase time projection chambers are also sensitive to $pp$ solar neutrinos via their elastic scattering off atomic electrons in the target material. Although this signal is subdominant within the Standard Model, it becomes significantly enhanced in many beyond the Standard Model scenarios, offering a unique opportunity to probe new physics in the low-energy regime. While the precision of current neutrino measurements from dark matter detectors remains lower than that achieved by dedicated neutrino experiments, their sensitivity to the tau neutrino component of solar neutrinos helps complete the overall picture, especially when investigating flavor-dependent new physics effects.

The Heliophysics Big Year was an extended year where major solar events engaged the public. It included two eclipses (annular on October 14, 2023 and total on April 8, 2024), plus solar max and the Parker Solar Probe perihelion December 24, 2024. After the eclipse of 2017, many millions more Americans planned to view the solar corona. We expanded our eclipse website with activities, citizen science projects, resources, training videos, equipment, and external links. We were the Southwest Regional Coordinator for Citizen CATE 2024 project, training the state coordinators and their teams with the equipment and procedures. We trained teachers at local, regional, national, and international workshops, providing eclipse viewing cards, lenses to make solar cup projectors, a safe viewing screen pattern, and access to the training materials. We made presentations to the media and hosted public events to demonstrate safe eclipse viewing techniques. HMNS hosted live viewing for the annular and total plus solstice and equinox events, reaching tens of thousands of people. HMNS also secured a grant to provide 100 eclipse viewing cards for every public school (8,800+) in Texas. We distributed another 57,000 eclipse viewers to teachers and the public. We appeared in media both in advance of the eclipses and as live commentators. The most lasting and impactful product was our planetarium show Totality, which was given away free and shown in various formats (flatscreen, fisheye, or prewarped). Over 180,000 views of the show and its animations have been documented. We continued to improve our space weather forecasting site, which correctly predicted the major solar storms of May 10-11 and October 8-10, 2024. In total, we reached nearly two million learners.

In this paper we argue that the information load carried by a black hole affects its classical perturbations. We refer to this phenomenon as the ``swift memory burden effect" and show that it is universal for objects of high efficiency of information storage. The effect is expected to have observable manifestations, for example, in mergers of astrophysical black holes in Einstein gravity. The black holes with different information loads, although degenerate in the ground state, respond very differently to perturbations. The strength of the imprint is controlled by the memory burden parameter which measures the fraction of the black hole's memory space occupied by the information load. This represents a new macroscopic quantum characteristics of a black hole. We develop a calculable theoretical framework and derive some master formulas which we then test on explicit models of black holes as well as on solitons of high capacity of information storage. We show that the effect must be significant for the spectroscopy of both astrophysical and primordial black holes and can be potentially probed in gravitational wave experiments. We also provide a proposal for the test of the memory burden phenomenon in a table-top laboratory setting with cold bosons.

Rapid and reliable detection and dissemination of source parameter estimation data products from gravitational-wave events, especially sky localization, is critical for maximizing the potential of multi-messenger astronomy. Machine learning based detection and parameter estimation algorithms are emerging as production ready alternatives to traditional approaches. Here, we report validation studies of AMPLFI, a likelihood-free inference solution to low-latency parameter estimation of binary black holes. We use simulated signals added into data from the LIGO-Virgo-KAGRA's (LVK's) third observing run (O3) to compare sky localization performance with BAYESTAR, the algorithm currently in production for rapid sky localization of candidates from matched-filter pipelines. We demonstrate sky localization performance, measured by searched area and volume, to be equivalent with BAYESTAR. We show accurate reconstruction of source parameters with uncertainties for use distributing low-latency coarse-grained chirp mass information. In addition, we analyze several candidate events reported by the LVK in the third gravitational-wave transient catalog (GWTC-3) and show consistency with the LVK's analysis. Altogether, we demonstrate AMPLFI's ability to produce data products for low-latency public alerts.