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Papers for Monday, Oct 06 2025

Papers with local authors

Refa M. Al-Amri, Jonelle L. Walsh, Emily R. Liepold, Chung-Pei Ma, Jenny E. Greene
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Paper 6 — arXiv:2510.02439
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Paper 6 — arXiv:2510.02439

The supermassive black hole (SMBH) in the giant elliptical galaxy M87 is one of the most well-studied in the local universe, but the stellar- and gas-dynamical SMBH mass measurements disagree. As this galaxy is a key anchor for the upper end of the SMBH mass$-$host galaxy relations, we revisit the central $3''\times 3''$ ($\sim 240\times240$ pc) region of M87 with the Near Infrared Spectrograph (NIRSpec) integral field unit (IFU) on the James Webb Space Telescope (JWST). We implement several improvements to the reduction pipeline and obtain high signal-to-noise spectra ($S/N \sim 150$) in single $0.''05 $ spaxels across much of the NIRSpec field of view. We measure the detailed shape of the stellar line-of-sight velocity distribution, parameterized by Gauss-Hermite moments up to $h_8$, in $\sim 2800$ spatial bins, substantially improving upon the prior high angular resolution studies of the M87 stellar kinematics. The NIRSpec data reveal velocities with $V \sim \pm 45$ km s$^{-1}$, velocity dispersions that rise sharply to $\sim$$420$ km s$^{-1}$ at a projected radius of 0.$''$45 (36 pc), and a slight elevation in $h_4$ toward the nucleus. We comprehensively test the robustness of the kinematics, including using multiple velocity template libraries and adopting different polynomials to adjust the template spectra. We find that the NIRSpec stellar kinematics seamlessly transition to recently measured large-scale stellar kinematics from optical Keck Cosmic Web Imager (KCWI) IFU data. These combined NIRSpec and KCWI kinematics provide continuous coverage from parsec to kiloparsec scales and will critically constrain future stellar-dynamical models of M87.

M. Abdullahi, R. Aloisio, F. Arneodo, S. Ashurov, U. Atalay, F. C. T. Barbato, R. Battiston, M. Bertaina, E. Bissaldi, D. Boncioli, L. Burmistrov, F. Cadoux, I. Cagnoli, E. Casilli, D. Cortis, A. Cummings, M. D'Arco, S. Davarpanah, I. De Mitri, G. De Robertis, A. Di Giovanni, A. Di Salvo, L. Di Venere, J. Eser, Y. Favre, S. Fogliacco, G. Fontanella, P. Fusco, S. Garbolino, F. Gargano, M. Giliberti, F. Guarino, M. Heller, T. Ibrayev, R. Iuppa, A. Knyazev, J. F. Krizmanic, D. Kyratzis, F. Licciulli, A. Liguori, F. Loparco, L. Lorusso, M. Mariotti, M. N. Mazziotta, M. Mese, M. Mignone, T. Montaruli, R. Nicolaidis, F. Nozzoli, A. Olinto, D. Orlandi, G. Osteria, P. A. Palmieri, B. Panico, G. Panzarini, D. Pattanaik, L. Perrone, H. Pessoa Lima, R. Pillera, R. Rando, A. Rivetti, V. Rizi, A. Roy, F. Salamida, R. Sarkar, P. Savina, V. Scherini, V. Scotti, D. Serini, D. Shledewitz, I. Siddique, L. Silveri, A. Smirnov, R. A. Torres Saavedra, C. Trimarelli, P. Zuccon, S. C. Zugravel
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Paper 46 — arXiv:2510.02844
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Paper 46 — arXiv:2510.02844

The Terzina telescope is designed to detect ultra-high energy cosmic rays (UHECRs) and Earth-skimming neutrinos from a 550 km low-Earth orbit (LEO) by observing Cherenkov light emitted by Extensive Air Showers (EAS) in the Earth's atmosphere pointing towards the telescope and in the field of view. In this contribution, a simulation chain for the Terzina telescope on board the NUSES mission will be presented. The chain encompasses all stages of the detection process, from event generation and EAS modelling with CORSIKA and EASCherSim to Geant4-based simulations of the telescope's geometry and optics, followed by modelling of the trigger system and silicon photomultiplier (SiPM) response. The Geant4 module includes the real CAD model of the telescope structure and optical components, with aspherical lenses manually implemented to ensure accurate representation of the optical efficiency and point spread function in Geant4. This comprehensive pipeline, developed using modular C++ code and Python tools for event analysis and reconstruction, produces detailed performance assessments of a telescope operating in a LEO mission but can be adapted for any high altitude Cherenkov telescope, making it a versatile tool for future observatory designs. The possibility of modelling balloons in the atmosphere has also been developed.

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Benjamin Hertzsch, Job Feldbrugge, Maé Rodriguez, Rien van de Weygaert

The caustic skeleton model is a mathematically rigorous framework for studying the formation history of the emerging cosmic web from the caustics in the underlying dark matter flow. In a series of two papers, we use constrained N-body simulations to investigate the different cosmic web environments. For the current study, we focus on the cosmic walls. We derive the conditions of the centres of proto-walls and analyse their evolution with N-body simulations. Next, we investigate the statistical properties of Zel'dovich pancakes by studying the number density of the cosmic wall centres in scale space and, for the first time, we calculate the Lagrangian-space volume of cosmic walls. Finally, we infer the mean density and velocity fields and the distribution of haloes around cosmic walls with a suite of physically realistic dark-matter-only simulations. We compare the cosmic walls obtained with the caustic skeleton framework with previously proposed saddle point conditions on the primordial potential and density perturbation.

William Cerny, Daisy Bissonette, Alexander P. Ji, Marla Geha, Anirudh Chiti, Simon E.T. Smith, Joshua D. Simon, Andrew B. Pace, Evan N. Kirby, Kim A. Venn, Ting S. Li, Alice M. Luna

The extremely-low-luminosity, compact Milky Way satellite Ursa Major III / UNIONS 1 (UMaIII/U1; $L_V = 11 \ L_{\odot}$; $a_{1/2} = 3$ pc) was found to have a substantial velocity dispersion at the time of its discovery ($\sigma_v = 3.7^{+1.4}_{-1.0} \rm \ km \ s^{-1}$), suggesting that it might be an exceptional, highly dark-matter-dominated dwarf galaxy with very few stars. However, significant questions remained about the system's dark matter content and nature as a dwarf galaxy due to the small member sample ($N=11$), possible spectroscopic binaries, and the lack of any metallicity information. Here, we present new spectroscopic observations covering $N=16$ members that both dynamically and chemically test UMaIII/U1's true nature. From higher-precision Keck/DEIMOS spectra, we find a 95% confidence level velocity dispersion limit of $\sigma_v< 2.3 \rm \ km \ s^{-1}$, with a $\sim$120:1 likelihood ratio now favoring the expected stellar-only dispersion of $\sigma_* \approx 0.1 \rm \ km \ s^{-1}$ over the original $3.7 \rm \ km \ s^{-1}$ dispersion. There is now no observational evidence for dark matter in the system. From Keck/LRIS spectra targeting the Calcium II K line, we also measure the first metallicities for 12 member stars, finding a mean metallicity of $\rm [Fe/H] = -2.65 \; \pm \, 0.1$ (stat.) $\pm \,0.3$ (zeropoint) with a metallicity dispersion limit of $\sigma_{\rm [Fe/H]} < 0.35$ dex (at the 95% credible level). Together, these properties are more consistent with UMaIII/U1 being a star cluster, though the dwarf galaxy scenario is not fully ruled out. Under this interpretation, UMaIII/U1 ranks among the most metal-poor star clusters yet discovered and is potentially the first known example of a cluster stabilized by a substantial population of unseen stellar remnants.

Eric Zhang, Laura V. Sales, Thales A. Gutcke, Yunwei Deng, Hui Li, Rüdiger Pakmor, Federico Marinacci, Volker Springel, Mark Vogelsberger, Paul Torrey, Boyuan Liu, Rahul Kannan, Aaron Smith, Greg L. Bryan

It is often understood that supernova (SN) feedback in galaxies is responsible for regulating star formation and generating gaseous outflows. However, a detailed look at their effect on the local interstellar medium (ISM) on small mass scales in simulations shows that these processes proceed in clearly distinct channels. We demonstrate this finding in two independent simulations with solar-mass resolution, LYRA and RIGEL, of an isolated dwarf galaxy. Focusing on the immediate environment surrounding SNe, our findings suggest that the large-scale effect of a given SN on the galaxy is best predicted by its immediate local density. Outflows are driven by SNe in diffuse regions expanding to their cooling radii on large ($\sim$ kpc) scales, while dense star-forming regions are disrupted in a localized (\sim pc) manner. However, these separate feedback channels are only distinguishable at very high numerical resolutions capable of following scales $\ll 10^3 M_\odot$. On larger scales, ISM densities are greatly mis-estimated, and differences between local environments of SNe become severely washed out. We demonstrate the practical implications of this effect by comparing with a mid-resolution simulation ($M_{\rm ptcl.} \sim 200 M_\odot$) of the same dwarf using the SMUGGLE model. The coarse-resolution simulation cannot self-consistently determine whether a given SN is responsible for generating outflows or suppressing star formation, suggesting that emergent galaxy physics such as star formation regulation through hot-phase outflows is fundamentally unresolvable by subgrid stellar feedback models, without appealing directly to simulations with highly resolved ISM.

Disc instability (DI) is a model aimed at explaining the formation of companions through the fragmentation of the circumstellar gas disc. Furthermore, DI could explain the formation of part of the observed exoplanetary population. We aim to provide a new comprehensive global model for the formation of companions via DI. The latter leads for the companions to orbital migration and damping of the eccentricities and inclinations. As it evolves, the disc is continuously monitored for self-gravity and fragmentation. When the conditions are satisfied, one (or several) clumps are inserted. The evolution of the clumps is then followed in detail. We showcased the model by performing a number of simulations for various initial conditions, from simple non-fragmenting systems to complex systems with many fragments. We confirm that the DIPSY model is a comprehensive and versatile global model of companion formation via DI. It enables studies of the formation of companions with planetary to low stellar masses around primaries with final masses that range from the brown dwarf to the B-star regime. We conclude that it is necessary to consider the many interconnected processes such as gas accretion, orbital migration, and N-body interactions, as they strongly influence the inferred population of forming objects. It is also clear that model assumptions play a key role in the determination of the systems undergoing formation.

We applied the global end-to-end model described in Paper~I of this series to perform a population synthesis of companions formed via disc instability (DI). By using initial conditions compatible with both observations and hydrodynamical simulations, and by studying a large range of primary masses (0.05-5 Msol), we can provide quantitative predictions of the outcome of DI. In the baseline population, we find that ~10 % of the discs fragment, and about half of these end up with a surviving companion after 100 Myr. 75\% of the companions are in the brown dwarf regime, 15 % are low-mass stars, and 10 % planets. At distances larger than ~100 au, DI produces planetary-mass companions on a low percent level. Inside of 100 AU, however, planetary-mass companions are very rare (low per mill level). The average companion mass is ~30 Mj scaling weakly with stellar mass. Most of the initial fragments do not survive on a Myr timescale; they either collide with other fragments or are ejected, resulting in a population of free-floating objects (about 1-2 per star). We also quantify several variant populations to critically assess some of our assumptions used in the baseline population. DI appears to be a key mechanism in the formation of distant companions with masses ranging from low-mass stars down to the planetary regime, contributing, however, only marginally to planetary mass objects inside of 100 AU. Our results are sensitive to a number of physical processes, which are not completely understood. Two of them, gas accretion and clump-clump collisions, are particularly important and need to be investigated further. Magnetic fields and heavy-element accretion have not been considered in our study, although they are also expected to affect the inferred population. We suggest acknowledging the importance of the gravito-turbulent phase, which most protoplanetary discs experience.

Zirui Chen, Zixuan Peng, Kate H. R. Rubin, Timothy M. Heckman, Matthew J. Hayes, Yakov Faerman, Crystal L. Martin, S. Peng Oh, Drummond B. Fielding

We present a fast and robust analytic framework for predicting surface brightness (SB) of emission lines in galactic winds as a function of radius up to $\sim 100$ kpc out in the circum-galactic medium. We model multi-phase structure in galactic winds by capturing emission from both the volume-filling hot phase (T $\sim 10^{6-7}$ K) and turbulent radiative mixing layers that host intermediate temperature gas at the boundaries of cold clouds (T $\sim 10^4$ K). Our multi-phase framework makes significantly different predictions of emission signatures compared to traditional single-phase models. We emphasize how ram pressure equilibrium between the cold clouds and hot wind in supersonic outflows, non-equilibrium ionization effects, and energy budgets other than mechanical energy from core-collapse supernovae affect our SB predictions and allow us to better match OVI observations in the literature. Our framework reveals that the optimal galactic wind properties that facilitate OVI emission observations above a detection limit of $\sim 10^{-18} \ \rm{erg \ s^{-1} \ cm^{-2} \ arcsec^{-2}}$ are star formation rate surface density $1 \lesssim \dot{\Sigma}_{\ast} \lesssim 20 \ M_{\odot}\ \rm{yr^{-1}\ kpc^{-2}}$, hot phase mass loading factor $\eta_{\rm M,hot} \sim 0.2 - 0.4$, and thermalization efficiency factor $\eta_{\rm E} \gtrsim 0.8$. These findings are consistent with existing observations and can help inform future target selections.

Behnood Bandi, Antoine Rocher, Aurélien Verdier, Jon Loveday, Zhuo Chen, Johan Richard, Jean-Paul Kneib, Tom Shanks, Michael J. I. Brown

The 4MOST Cosmology Redshift Survey (CRS) will obtain nearly 5.4 million spectroscopic redshifts over $\sim5700$\,deg$^2$ to map large-scale structure and enable measurements of baryon acoustic oscillations (BAOs), growth rates via redshift-space distortions, and cross-correlations with weak-lensing surveys. We validate the target selections, photometry, masking, systematics and redshift distributions of the CRS Bright Galaxy (BG) and Luminous Red Galaxy (LRG) target catalogues selected from DESI Legacy Surveys DR10.1 imaging. We measure the angular two-point correlation function, test masking strategies, and recover redshift distributions via cross-correlation with DESI DR1 spectroscopy. For BG, we adopt Legacy Survey \texttt{MASKBITS} that veto bright stars, SGA large galaxies, and globular clusters; for LRG, we pair these with an unWISE W1 artefact mask. These choices suppress small-scale excess power without imprinting large-scale modes. A Limber-scaling test across BG $r$-band magnitude slices shows that, after applying the scaling, the $w(\theta)$ curves collapse to a near-common power law over the fitted angular range, demonstrating photometric uniformity with depth and consistency between the North (NGC) and South (SGC) Galactic Caps. Cross-correlations with DESI spectroscopy recover the expected $N(z)$, with higher shot noise at the brightest magnitudes. For LRGs, angular clustering in photo-$z$ slices ($0.4\le z<1.0$) is mutually consistent between the DECaLS and DES footprints at fixed $z$ and is well described by an approximate power law once photo-$z$ smearing is accounted for; halo-occupation fits yield results consistent with recent LRG studies. Together, these tests indicate that the masks and target selections yield uniform clustering statistics, supporting precision large-scale structure analyses with 4MOST CRS.

Victoria L. Butler, James J. Bock, Dongwoo T. Chung, Abigail T. Crites, King Lau, Ian Lowe, Dan P. Marrone, Evan C. Mayer, Benjamin J. Vaughan, Michael Zemcov

Transition Edge Sensor (TES) bolometers are a well-established technology with a strong track record in experimental cosmology, making them ideal for current and future radio astronomy instruments. The Tomographic Ionized-carbon Mapping Experiment (TIME), in collaboration with JPL, has developed advanced silicon nitride leg isolated superconducting titanium detectors for 200 to 300 GHz observations of the Epoch of Reionization. Compared to their MHz counterparts, bolometers operating in this frequency range are less common because of their large absorber size and fragility. TIME aims to fabricate a total of 1920 high frequency (HF) and low frequency (LF) detectors to fully populate the focal plane. TIME has successfully developed HF (230 to 325 GHz) and LF (183 to 230 GHz) wafers that are physically robust and perform well at cryogenic temperatures (300 mK). Recent laboratory tests have shown high optical efficiencies for the LF wafers (30 to 40%), but low device yield for the HFs. To address this, new HF modules have been designed with improved cabling and a reduced backshort distance, and are expected to perform similarly to LFs in a similar lab setting. We report on the development of these detectors as well as recent laboratory and on sky tests conducted at the Arizona Radio Observatory's (ARO) 12 meter prototype antenna at Kitt Peak National Observatory.

Kuldeep Belwal, D. Bisht, Ing-Guey Jiang, R. K. S. Yadav, Ashish Raj, Geeta Rangwal, Arvind K. Dattatrey, Mohit Singh Bisht, Alok Durgapal

We present a kinematic and dynamical analysis of six Galactic open clusters NGC~2204, NGC~2660, NGC~2262, Czernik~32, Pismis~18, and NGC~2437, using \textit{Gaia}~DR3. We used Bayesian and Gaussian Mixture Model (GMM) methods to identify cluster members, but chose GMM because it's more appropriate for low-mass stars. Estimated distances range from 1.76 to 4.20~kpc and ages from 0.199 to 1.95~Gyr, confirming their intermediate-age nature. King model fits indicate compact morphologies, with core radii of 1--10~arcmin and cluster radii of 5--24~arcmin. We identify 13 BSS and 3 YSS members, whose central concentrations suggest origins via mass transfer or stellar collisions. The mass function slopes (0.96--1.19) are flatter than the Salpeter value, which indicates that these clusters have undergone dynamical mass segregation. Orbit integration within a Galactic potential indicates nearly circular orbits (eccentricities 0.02--0.10), vertical excursions within $\pm$132~pc, and guiding radii near the solar circle, suggesting disk confinement. These clusters likely formed in the thin disk and are shaped by Galactic tidal perturbations, facilitating the rapid loss of low-mass members. Additionally, twelve variable stars were found across four clusters using \textit{TESS} light curves, including $\gamma$~Doradus and SPB pulsators, eclipsing binaries, and a yellow straggler candidate. Periods were derived via Lomb-Scargle analysis. Two eclipsing binaries (TIC~94229743 and TIC~318170024) were modeled using PHOEBE, yielding mass ratios of 1.37 and 2.16, respectively. Our findings demonstrate that integrating orbital dynamics and variable star studies presents valuable insights into the evolutionary pathways of open clusters.

Enrico Biancalani, Edward Balaban, Ruslan Belikov, Eduardo Bendek, Valeri Frumkin, Israel Gabay, Guangjun Gao, Qian Gong, Christine Gregg, Tyler Groff, Joseph Howard, Omer Luria, Michael McElwain, Lee Mundy, Rachel Ticknor, Sylvain Veilleux, Neil Zimmerman

$\textbf{Fluidic Telescopes}$ | We present a conceptual framework for optically designing space-assembled telescopes whose primary mirror is formed $\textit{in situ}$ via the enabling, scale-invariant technology of fluidic shaping. In-space assembly of optical reflectors can solve light-gathering aperture scaling, which currently limits space-borne optical telescopes. Our compass reduces the top-level optical design trade to three types of avenues -- a fluidic pathway, a legacy one building upon the James Webb Space Telescope, and hybrid solutions -- with a focus on exo-Earths. A primarily fluidic pathway leads, in the first place, to a post-prime-focus architecture. We apply this configuration to propose the tentative optical design for a ~1-m technology demonstrator and pathfinder for fluidic-telescope apertures scaling up to many tens of meters in diameter. $\textbf{Dual-Configuration Spectrographs}$ | The Habitable Worlds Observatory (HWO) will be the first mission equipped for the high-contrast direct imaging and remote spectral characterization, in reflected starlight, of exo-Earths in our galactic neighborhood. We present a novel concept for a compact, dual-configuration HWO spectrograph tailored for a broad wavelength range covering at least 600--1000 nm. Our design can interchange dispersive elements via a slider mechanism while preserving the rest of the optical path, enabling both a spectral resolving power $R$~140 integral-field spectrograph and a single- or multi-object spectrograph with $R$ on the order of 10$^3$. Although $R$~140 is near-optimal for the $O_2$ absorption $A$-band around 760 nm, higher values of $R$ can be utilized with spectral cross-correlation matched-filter techniques to enhance, e.g., HWO's atmospheric characterization capabilities.

In order for an inflationary universe to evolve into a hot universe, a process known as reheating is required. However, the precise mechanism of reheating remains unknown. We show that if the reheating is triggered by thermal dissipation effects, distinctive features appear in the spectrum of primordial gravitational waves. This suggests a possible way to observationally probe the physics of reheating.

The presence of NH$_3$-bearing components on icy planetary bodies has important implications for their geology and potential habitability. Here, I report the detection of a characteristic NH$_3$ absorption feature at 2.20 $\pm$ 0.02 $\mu$m on Europa, identified in an observation from the Galileo Near Infrared Mapping Spectrometer. Spectral modeling and band position indicate that NH$_3$-hydrate and NH$_4$-chloride are the most plausible candidates. Spatial correlation between detected ammonia signatures and Europa's microchaos, linear, and band geologic units suggests emplacement from the underground or shallow subsurface. I posit that NH$_3$-bearing materials were transported to the surface via effusive cryovolcanism or similar mechanisms during Europa's recent geological past. The presence of ammoniated compounds implies a thinner ice shell (Spohn & Schubert, 2003) and a thicker, chemically reduced, high-pH subsurface ocean on Europa (Hand et al. 2009). With the detection of NH$_3$-bearing components, this study presents the first evidence of a nitrogen-bearing species on Europa -- an observation of astrobiological significance given nitrogen's essential role in the chemistry of life.

Jose Luis Gragera-Más (1 and 2), Santiago Torres (3), Alexander James Mustill (4), Eva Villaver (5 and 6) ((1) Centro de Astrobiología (CAB) CSIC-INTA, (2) Departamento de Física de la Tierra y Astrofísica, Facultad de Ciencias Físicas, Universidad Complutense de Madrid, (3) Institute of Science and Technology Austria (ISTA), (4) Lund Observatory, Division of Astrophysics, Department of Physics, Lund University, (5) Instituto de Astrofísica de Canarias, (6) Universidad de La Laguna (ULL))

Beta Pictoris is an A-type star hosting a complex planetary system with two massive gas giants and a prominent debris disk. Variable absorption lines in its stellar spectrum have been interpreted as signatures of exocomets (comet-like bodies transiting the star). Stellar flybys can gravitationally perturb objects in the outer comet reservoir, altering their orbits and potentially injecting them into the inner system, thereby triggering exocomet showers. We aim to assess the contribution of stellar flybys to the observed exocomet activity by reconstructing the stellar encounter history of beta Pictoris in the past and future. We used Gaia DR3 data, supplemented with radial velocities from complementary spectroscopic surveys, to compile a catalogue of stars currently within 80 pc of beta Pictoris. Their orbits were integrated backward and forward in time in an axisymmetric Galactic potential (Gala package) to identify encounters within 2 pc of the system. We identified 99 416 stars within 80 pc of beta Pictoris at present with resolved kinematics. Among these, 49 stars (including the eight components of five binaries) encounter beta Pictoris within 2 pc between -1.5 Myr and +2 Myr. For four of the binaries, the centre-of-mass trajectories also pass within 2 pc. We estimate the sample to be more than 60 % complete within 0.5 Myr of the present. Despite beta Pictoris being the eponym of its famous moving group, none of the identified encounters involved its moving group members; all are unrelated field stars. We find no encounter capable of shaping observed disc structures, although stellar flybys may contribute to the long-term evolution of a potential Oort Cloud. Our catalogue constitutes the most complete reconstruction of the beta Pictoris encounter history to date and provides a robust foundation for future dynamical simulations.

Basheer Kalbouneh, Christian Marinoni, Roy Maartens, Julien Bel, Jessica Santiago, Chris Clarkson, Maharshi Sarma, Jean-Marc Virey

Without making any assumption on the underlying geometry and metric of the local Universe, we provide a measurement of the expansion rate fluctuation field using the Cosmicflows-4 and Pantheon+ samples in the redshift range $0.01 < z < 0.1$ ($30 \,h^{-1}\,\mathrm{Mpc} < R < 300\,h^{-1}\,\mathrm{Mpc}$). The amplitude of the anisotropic fluctuations is found to be of order a few percent relative to the monopole of the expansion rate. We further decompose the expansion rate fluctuation field into spherical harmonic components and analyze their evolution with redshift across the studied redshift range. At low redshift, the dipole is clearly dominant, with an amplitude of $\sim (2.2 \pm 0.15)\times 10^{-2}$, significantly larger than the higher--order modes. As redshift increases, the dipole amplitude steadily decreases, reaching roughly half its value in the highest redshift bin investigated. The quadrupole is also significant, at about half the dipole amplitude, and persists across all redshift bins, with no clear decreasing trend, although uncertainties grow at higher redshift. A nonzero octupole is also detected at low redshift. The dipole, quadrupole, and octupole components are found to be aligned, exhibiting axial symmetry around a common axis ($l = 295^\circ,\, b = 5^\circ$). We interpret the observed fluctuations in the expansion rate within the framework of covariant cosmography. Our results indicate that the multipoles of the expansion rate fluctuation field are primarily driven by a strong quadrupole in the covariant Hubble parameter, together with dipole and octupole contributions from the covariant deceleration parameter. These few parameters suffice to reconstruct the luminosity distance with high precision out to $z \sim 0.1$, in a manner that is model--independent, non--perturbative, and free from assumptions about peculiar velocities.

Rogemar A. Riffel, Luis Colina, José Henrique Costa-Souza, Vincenzo Mainieri, Miguel Pereira Santaella, Oli L. Dors, Ismael García-Bernete, Almudena Alonso-Herrero, Anelise Audibert, Enrica Bellocchi, Andrew J. Bunker, Steph Campbell, Françoise Combes, Richard I. Davies, Tanio Díaz-Santos, Fergus R. Donnan, Federico Esposito, Santiago García-Burillo, Begoña García-Lorenzo, Omaira González Martín, Houda Haidar, Erin K. S. Hicks, Sebastian F. Hoenig, Masatoshi Imanishi, Alvaro Labiano, Enrique Lopez-Rodriguez, Christopher Packham, Cristina Ramos Almeida, Dimitra Rigopoulou, David Rosario, Gabriel Luan Souza-Oliveira, Montserrat Villar Martín, Oscar Veenema, Lulu Zhang

Active galactic nuclei (AGN), star formation (SF), and galaxy interactions can drive turbulence in the gas of the ISM, which in turn plays a role in the SF within galaxies. The impact on molecular gas is of particular importance, as it serves as the primary fuel for SF. Our goal is to investigate the origin of turbulence and the emission of molecular gas, as well as low- and intermediate-ionization gas, in the inner few kpc of both AGN hosts and SF galaxies. We use JWST MIRI/MRS observations of a sample consisting of 54 galaxies at z<0.1. We present fluxes of the H2 S(5)6.9091, [Ar II]6.9853, [FeII]5.3403, and [Ar III]8.9914 lines, along with velocity dispersion from W80. For galaxies with coronal emission, [Mg V]5.6098 is also included. Line ratios are compared to photoionization and shock models to explore the origin of the gas emission. AGNs exhibit broader emission lines than SFGs, with the largest velocity dispersions observed in radio-strong (RS) AGNs. H2 gas is less turbulent compared to ionized gas, while coronal gas presents higher velocity dispersions. The W80 values for the ionized gas exhibits a decrease from the nucleus out to radii of approximately 0.5--1 kpc, followed by an outward increase up to 2-3 kpc. In contrast, the H2 line widths generally display increasing profiles with distance from the center. Correlations W80 and line ratios such as H2 S(5)/[ArII] and [FeII]/[ArII] indicate that the most turbulent gas is associated with shocks, enhancing H2 and [FeII] emissions. We speculate that these shocked gas regions are produced by AGN outflows and jet-cloud interactions in AGN-dominated sources, while in SFGs, they may be created by stellar winds and mergers. This shock-induced gas heating may be an important mechanism of AGN (or stellar) feedback, preventing the gas from cooling and forming new stars.

Xinghai Zhao, Guobao Tang, Paola Gonzalez, Grant J. Mathews, Lara Arielle Phillips

It has been suggested that the Plane of Satellites (PoS) phenomenon may imply a tension with current $\Lambda$CDM cosmology since a Milky-Way (MW)-like PoS is very rare in simulations. In this study, we analyze a large sample of satellite systems of MW-like galaxies in the IllustrisTNG simulations. We analyze their spatial aspect ratio, orbital pole dispersion, Gini coefficient, radial distribution, and bulk satellite velocity relative to the host galaxy. These are compared to the observed Milky~Way PoS. We identified galaxy samples in two mass ranges ($0.1 - 0.8 \times 10^{12} $ M$_\odot$ and $0.8 - 3.0 \times 10^{12}$ M$_\odot$). We find for both mass ranges that only $\sim$ 1 percent of MW-like galaxies contain a PoS similar to that of the MW. Nevertheless, these outliers occur naturally in $\Lambda$CDM cosmology. We analyze the formation, environment, and evolution of the PoS for nine systems that are most MW-like. We suggest that a PoS can form from one or more of at least five different processes. A massive Magellanic~Cloud (MC)-like satellite is found in 1/3 of the systems and probably plays an important role in the PoS formation. We find a tendency for about half of the satellites to have recently arrived at $z < 0.5$, indicating that a MW-like PoS is a recent and transient phenomenon. We also find that a spin up of the angular momentum amplitude of the most massive satellites is an indicator of the recent in-fall of the PoS satellites.

N. Deg, K. Spekkens, N. Arora, R. Dudley, H. White, A. Helias, J. English, T. O'Beirne, V. Kilborn, G. Ferrand, M. L. A. Richardson, B. Catinella, L. Cortese, H. Dénes, A. Elagali, B. -Q. For, K. Lee-Waddell, J. Rhee, L. Shao, A. X. Shen, L. Staveley-Smith, T. Westmeier, O. I. Wong

Many of the tensions in cosmological models of the Universe lie in the low mass, low velocity regime. Probing this regime requires a statistically significant sample of galaxies with well measured kinematics and robustly measured uncertainties. WALLABY, as a wide area, untargetted HI survey is well positioned to construct this sample. As a first step towards this goal we develop a framework for testing kinematic modelling codes in the low resolution, low $S/N$, low rotation velocity regime. We find that the WALLABY Kinematic Analysis Proto-Pipeline (WKAPP) is remarkably successful at modelling these galaxies when compared to other algorithms, but, even in idealized tests, there are a significant fraction of false positives found below inclinations of $\approx 40^{\circ}$. We further examine the 11 detections with rotation velocities below $50~\kms$ in the WALLABY pilot data releases. We find that those galaxies with inclinations above $40^{\circ}$ lie within $1-2~\sigma$ of structural scaling relations that require reliable rotation velocity measurements, such as the baryonic Tully Fisher relation. Moreover, the subset that have consistent kinematic and photometric inclinations tend to lie nearer to the relations than those that have inconsistent inclination measures. This work both demonstrates the challenges faced in low-velocity kinematic modelling, and provides a framework for testing modelling codes as well as constructing a large sample of well measured low rotation models from untargetted surveys.

Global search and optimization of long-duration, low-thrust spacecraft trajectories with the indirect method is challenging due to a complex solution space and the difficulty of generating good initial guesses for the costate variables. This is particularly true in multibody environments. Given data that reveals a partial Pareto optimal front, it is desirable to find a flexible manner in which the Pareto front can be completed and fronts for related trajectory problems can be found. In this work we use conditional diffusion models to represent the distribution of candidate optimal trajectory solutions. We then introduce into this framework the novel approach of using Markov Chain Monte Carlo algorithms with self-supervised fine-tuning to achieve the aforementioned goals. Specifically, a random walk Metropolis algorithm is employed to propose new data that can be used to fine-tune the diffusion model using a reward-weighted training based on efficient evaluations of constraint violations and missions objective functions. The framework removes the need for separate focused and often tedious data generation phases. Numerical experiments are presented for two problems demonstrating the ability to improve sample quality and explicitly target Pareto optimality based on the theory of Markov chains. The first problem does so for a transfer in the Jupiter-Europa circular restricted three-body problem, where the MCMC approach completes a partial Pareto front. The second problem demonstrates how a dense and superior Pareto front can be generated by the MCMC self-supervised fine-tuning method for a Saturn-Titan transfer starting from the Jupiter-Europa case versus a separate dedicated global search.

Michael W. McElwain, Dimitri Mawet, Jean-Baptiste Ruffio, Roser Juanola Parramon, Kellen Lawson, Hervé Le Coroller, Christian Marois, Max Millar-Blanchaer, Bijan Nemati, Susan Redmond, Bin Ren, Laurent Pueyo, Christopher Stark, Scott Will

The discovery and characterization of habitable worlds was the top scientific recommendation of the Astro2020 decadal survey and is a key objective of the Habitable Worlds Observatory. Biosignature identification drives exceedingly challenging observations, which require raw contrasts of roughly 10$^{-10}$ contrast and ultimately, 1$\sigma$ photometric precision of roughly 3$\times 10^{-12}$ contrast. Despite significant advances for the Nancy Grace Roman Space Telescope's Coronagraph Instrument, technological gaps still exist in a wide range of technologies such as starlight suppression, deformable mirrors, wavefront control, low noise detectors, and high-contrast spectroscopy. Even with these new technologies matured, the Habitable Worlds Observatory must carefully obtain the observations and rely on post-processing of the data to achieve its science objectives. During the START and TAG efforts, a working group was convened to explore the Coronagraph Concept of Operations and Post Processing (COPP) in the context of the Habitable Worlds Observatory. This COPP working group evaluated coronagraphic concept of operations to enable different post processing approaches, such as reference differential imaging and angular differential imaging, polarization differential imaging, orbital differential imaging, coherent differential imaging, spectral processing, and point-spread function subtraction algorithms that incorporate ancillary telemetry and data. Future integrated modeling simulations and testbed demonstrations are needed to determine the achievable post processing gains for each approach. We report a summary of this working group's activities and findings, as well as an outlook for maturation of these techniques and infusion into the Habitable Worlds Observatory technology portfolio.

Marvin Morgan, Brendan P. Bowler, Quang H. Tran, Robert A. Wittenmyer, Duncan J. Wright, George Zhou, Tyler R. Fairnington

Giant planets are expected to predominantly form beyond the water ice line and occasionally undergo inward migration. Unlike hot Jupiters, which can result from high-eccentricity tidal migration, warm Jupiters between 0.1-1 AU ($\approx$10--365 d) are in many ways more challenging to explain because they reside outside the tidal influence of their host stars. Warm Jupiters should therefore preserve traces of their origins as their eccentricities are directly related to their past interactions. We analyze the eccentricities of 200 warm Jupiters orbiting 194 Sun-like host stars (with FGKM spectral types) using 18,587 RV measurements across 40 high-resolution spectrographs. RVs are compiled from the literature and are supplemented with 540 new observations from MINERVA-Australis at Mt. Kent Observatory and the Habitable-zone Planet Finder spectrograph at McDonald Observatory's Hobby-Eberly Telescope, which are timed to improve eccentricity constraints by sampling orbits near periastron passage. The overarching goal of this program is to establish the relative importance of giant planet migration channels through the largest homogeneous analysis of warm Jupiter orbital properties to date. In particular, we evaluate and compare the impact of different system architectures and host star characteristics on the population-level eccentricity distributions of warm Jupiters. Here, we present the target sample, observations, orbit fitting procedure, and parameter summary statistics of our survey. All orbit fit solutions, parameter posterior chains, and merged RV tables for each system are made publicly available.

Stellar metallicity encodes the integrated effects of gas inflow, star formation, and feedback-driven outflow, yet its connection to galaxy structure remains poorly understood. Using SDSS-IV MaNGA, we present the direct observational evidence that, at fixed stellar mass, smaller central galaxies are systematically more metal-rich, with a Spearman's rank correlation coefficient reaching $R_{\rm s}\approx -0.4$. The semi-analytical model L-GALAXIES reproduces this anti-correlation, albeit with a stronger amplitude ($R_{\rm s}\approx -0.8$). Within this framework, the trend cannot be explained by differences in gravitational potential depth or star formation history. Instead, smaller galaxies attain higher stellar metallicities because their elevated star formation efficiencies accelerate chemical enrichment, and, at fixed stellar mass, they inhabit less massive haloes, which makes their recycled inflows more metal-rich. The gas-regulator model demonstrates that star formation efficiency affects stellar metallicity when the system has not long remained in equilibrium, which is shown to be the case for central galaxies with $M_{\rm star}\lesssim 10^{10.5}\rm M_\odot$ in both L-GALAXIES and observation. The model also suggests a testable signature that, at fixed stellar mass, larger or lower-metallicity galaxies should inhabit more massive haloes than their smaller and higher-metallicity counterparts, providing a direct and testable imprint of the galaxy size-stellar metallicity relation on the galaxy-halo connection.

Warm Jupiters with orbital periods of $\approx$10-365 d represent a population of giant planets located well within the water ice line but beyond the region of tidal influence of their host star relevant for high-eccentricity tidal migration. Orbital eccentricities offer important clues about the formation and dynamical history of warm Jupiters because in situ formation and disk migration should imprint near-circular orbits whereas planet scattering should excite eccentricities. Based on uniform Keplerian fits of 18,587 RVs targeting 200 warm Jupiters, we use hierarchical Bayesian modeling to evaluate the impact of host star metallicity, stellar mass, and orbital separation on the reconstructed population-level eccentricity distributions. Warm Jupiters take on a broad range of eccentricities, and their population-level eccentricities are well modeled using a Beta distribution with $\alpha$ = 1.00$^{+0.09}_{-0.08}$ and $\beta$ = 2.79$^{+0.28}_{-0.26}$. We find that 27$^{+3}_{-4}\%$ of warm Jupiters have eccentricities consistent with near-circular orbits ($e$ $<$ 0.1), suggesting that most warm Jupiters (73$^{+3}_{-3}\%$) detected are dynamically hot. Warm Jupiters orbiting metal-rich stars are more eccentric than those orbiting metal-poor stars -- in agreement with earlier findings -- but no differences are observed as a function of stellar host mass or orbital separation, at least within the characteristic ranges probed by our sample ($\approx$0.5--2.0 $M_{\odot}$ and 0.1--1 AU, respectively). In this sense, metallicity plays a larger role in shaping the underlying eccentricity distribution of warm Jupiters than stellar mass or final orbital distance. These results are broadly consistent with planet scattering playing a major role in shaping the orbital architectures of close-in giant planets.

G.A.Gontcharov, A.A.Marchuk, S.S.Savchenko, A.V.Mosenkov, V.B.Il'in, D.M.Poliakov, A.A.Smirnov, H.Krayani

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We present a new two-dimensional (2D) map of total Galactic extinction, $A_\mathrm{V}$, across the entire dust half-layer from the Sun to extragalactic space for Galactic latitudes $|b|>13$ deg, as well as a three-dimensional (3D) map of $A_\mathrm{V}$ within 2~kpc of the Sun. These maps are based on $A_\mathrm{V}$ and distance estimates derived from a dataset, which utilizes {\it Gaia} Data Release 3 parallaxes and multi-band photometry for nearly 100 million dwarf stars. We apply our own corrections to account for significant systematics in this dataset. Our 2D map achieves an angular resolution of 6.1~arcmin, while the 3D map offers a transverse resolution of 3.56~pc -- corresponding to variable angular resolution depending on distance -- and a radial resolution of 50~pc. In constructing these maps, we pay particular attention to the solar neighborhood (within 200~pc) and to high Galactic latitudes. The 3D map predicts $A_\mathrm{V}$ from the Sun to any extended object within the Galactic dust layer with an accuracy of $\sigma(A_\mathrm{V}) = 0.1$~mag. The 2D map provides $A_\mathrm{V}$ estimates for the entire dust half-layer up to extragalactic distances with an accuracy of $\sigma(A_\mathrm{V}) = 0.07$~mag. We provide $A_\mathrm{V}$ estimates from our maps for various classes of extended celestial objects with angular size primarily in the range of 2--40~arcmin, including 19,809 galaxies and quasars, 170 Galactic globular clusters, 458 open clusters, and several hundreds molecular clouds from two lists. We also present extinction values for 8,293 Type Ia supernovae. Comparison of our extinction estimates with those from previous maps and literature sources reveals systematic differences, indicating large-scale spatial variations in the extinction law and suggesting that earlier 2D reddening maps based on infrared dust emission tend to underestimate low extinction values.

Nolan Habel, Omnarayani Nayak, Patrick J. Kavanagh, Olivia C. Jones, Margaret Meixner, Guido De Marchi, Laura Lenkic, Alec S. Hirschauer, Katia Biazzo, Jeroen Jaspers, Conor Nally, Massimo Robberto, Ciaran Rogers, Elena Sabbi, Beth A. Sargent, Peter Zeidler

We present mid-infrared spectroscopic observations of intermediate- to high-mass young stellar objects (YSOs) in the low-metallicity star-forming region NGC 346 located within the Small Magellanic Cloud (SMC). We conduct these integral-field-unit observations with the Mid-Infrared Instrument Medium Resolution Spectroscopy instrument on board JWST. The brightest and most active star-forming region in the SMC, NGC 346 has a metallicity of $\sim$1/5 $Z_{\odot}$, analogous to the era when star formation in the early Universe ($z$$\simeq$2) peaked. We discuss the emission and absorption features present in the spectral energy distributions (SEDs) of five YSOs with coverage from 4.9-27.9$\mu$m and three other sources with partial spectral coverage. Via SED model-fitting, we estimate their parameters, finding masses ranging from 2.9-18.0 M$_{\odot}$. These targets show dusty silicates, polycyclic aromatic hydrocarbons and ices of CO$_2$, CO, H$_2$O and CH$_3$OH in their protostellar envelopes. We measure emission from H$_2$ and atomic fine-structure lines, suggesting the presence of protostellar jets and outflows. We detect H I lines indicating ongoing accretion and estimate accretion rates for each source which range from 2.50x10$^{-6}$-2.23x10$^{-4}$ M$_{\odot}$yr$^{-1}$ based on H I (7-6) line emission. We present evidence for a $\sim$30,000AU protostellar jet traced by fine-structure, H I and H$_2$ emission about the YSO Y535, the first detection of a resolved protostellar outflow in the SMC, and the most distant yet detected.

A. C. Bradley, Z. J. Smeaton, M. D. Filipovic, N. F. H. Tothill, R. Z. E. Alsaberi, J. D. Collier, Y. A. Gordon, A. M. Hopkins, H. Zakir

We present a radio-continuum detection of the well-known Wolf-Rayet star WR40 at 943.5 MHz using observations from the EMU survey. We find that the shell surrounding WR40, known as RCW 58, has a flux density of 158.9+/-15.8 mJy and the star itself is 0.41+/-0.04 mJy. The shell size is found to be 9' x 6', which matches well with the shell in Halpha and is similarly matched to the shell at 22 um in infrared. Using Gaia data, we derive a linear size of 7.32(+/-0.34) x 4.89(+/-0.23) pc at a distance of 2.79+/-0.13 kpc. We use previous ATCA observations at 8.64, 4.80, and 2.4 GHz to determine a spectral index of WR40, which is estimated to be alpha = 0.80+/-0.11, indicating that the emission from the star is thermal.

Shota Miyazaki, Hajime Kawahara (Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Japan)

We introduce microJAX, the first fully differentiable implementation of the image-centered ray-shooting (ICRS) algorithm for gravitational microlensing. Built on JAX and its XLA just-in-time compiler, microJAX exploits GPU parallelism while providing exact gradients through automatic differentiation. The current release supports binary- and triple-lens geometries, including limb-darkened extended-source effects, and delivers magnifications that remain differentiable for all model parameters. Benchmarks show that microJAX matches the accuracy of established packages and attains up to a factor of $\sim$5-6 speed-up in the small-source, limb-darkened regime on an NVIDIA A100 GPU. Since the model is fully differentiable, it integrates seamlessly with probabilistic programming frameworks, enabling scalable Hamiltonian Monte Carlo and variational inference workflows. Although the present work focuses on standard microlensing magnification models, the modular architecture is designed to support upcoming implementations of microlensing higher-order effects, while remaining compatible with external likelihood frameworks that incorporate advanced noise models. microJAX thus provides a robust foundation for precise and large-scale surveys anticipated in the coming decade, including the Nancy Grace Roman Space Telescope, where scalable, physically self-consistent inference will be essential for maximizing scientific return.

Bernardo Cornejo, Halim Ashkar, Matteo Cerruti, Ilja Jaroschewski, Pierre Pichard, Santiago Pita, Fabian Schussler (on behalf of the H.E.S.S. Collaboration)

Multi-wavelength and multi-messenger astrophysics have experienced rapid growth over the past decade, seeking a complete picture of different cosmic phenomena. Transient sources, in particular, benefit from the input of multi-messenger observations, offering complementary perspectives on the same event while maximizing the detection probability of a rapidly fading signal. In this context, Gravitational Wave (GW) detections serve as perfect triggers for potential counterpart detections. Notably, a GW alert could be associated with a Gamma-Ray Burst (GRB), jetted cataclysmic events produced either by the collision of a binary neutron star system or a core-collapse supernova. These sources also radiate across the electromagnetic spectrum, allowing detection by X- and gamma-ray instruments aboard various satellites and thus enabling multi-wavelength triggering opportunities. The strong interest in minimizing reaction time to capture the full-time evolution of the emission, together with the often challenging localization uncertainties of the alerts, underscores the need for rapid and well-coordinated follow-up programs such as the one developed by the H.E.S.S. Collaboration. This contribution will give an overview of the transient follow-up strategy carried out by the H.E.S.S. Collaboration, from the external alert trigger and the automatic reaction of the observatory to the various analysis steps of the obtained observations. To illustrate this comprehensive strategy, we will show two examples of follow-up observations of both GRBs and GWs, highlighting key results and challenges in the search for an associated high-energy gamma-ray emission.

A. S. Rajpurohit, V. Kumar, K. Srivastava Mudit, L. Labadie, K. Rajpurohit, J. G. Fernandez-Trincado

Most M dwarfs show higher chromospheric activity, often exceeding solar levels. Characterizing stellar activity is essential, particularly since these stars are prime targets in the search for habitable exoplanets. We investigate the stellar activity of active M dwarfs using TESS photometry combined with spectroscopic observations. We explore relations between flare occurrence rate (FOR), flare energies, rotation period, starspot filling factor, and chromospheric indicators. We also examine correlations between flare amplitude, duration, and cumulative flare frequency distributions to probe the mechanisms behind magnetic activity. We find that FOR is flat across spectral types M0-M4 but declines for cooler M dwarfs. Rapid rotators ($P_{\rm rot} < 1$ day) display significantly higher FOR and flare activity. M dwarfs with higher FOR tend to have lower flare amplitudes, suggesting that frequent flares are generally less energetic. For stars with 0.15--0.76 $M_\odot$, the median $L_{H\alpha}/L_{\rm bol}$ varies by a factor of 2.5 across mass bins of 0.1 $M_\odot$, while $\Delta$EW decreases by 92\%. The cumulative flare frequency distributions show a decrease in the power-law slope from M0 to M5, with $\alpha$ ranging from 1.68 to 1.95. Our results indicate a transition in stellar activity near M4, where stronger H$\alpha$ emission coincides with higher FOR. We confirm that chromospheric and flare activity follow a power-law relation, highlighting the interplay between magnetic fields and flaring in M dwarfs. We also find that fast rotators sustain frequent flaring through strong dynamos, and that highly active stars dissipate magnetic energy via numerous low-energy flares rather than rare high-energy ones.

Antonia Fernández-Figueroa, Glenn G. Kacprzak, Tania M. Barone, Nikole M. Nielsen, Kate H. R. Rubin, Andrew J. Pitts, Barbara Mazzilli Ciraulo

We present Keck/LRIS spectroscopy of seven isolated galaxy-quasar pairs at $0.4 \leq z \leq 0.6$, each exhibiting ultra-strong MgII absorption ($W_{r,2796} \geq 3$ Å), probing both down-the-barrel and transverse gas flows. Down-the-barrel galaxy spectra reveal outflows in three galaxies ($v = 19$ to $311$ km s$^{-1}$) and inflows in five ($v = 61$ to $361$ km s$^{-1}$), including one system showing inflows and outflows simultaneously. All galaxies with detected inflows are below the star-forming main sequence, suggesting that they might be actively replenishing their gas reservoirs. Outflows have a mean covering fraction of $C_{f, \rm out}=0.5$, whereas inflows show a lower average of $C_{f, \rm in}=0.3$. Mass flow rates span $\dot{M}_{\rm in} = 0.01-1.18$ $M_{\odot} \mathrm{yr}^{-1}$ for inflows and $\dot{M}_{\rm out} = 0.23-1.03$ $M_{\odot}\mathrm{yr}^{-1}$ for outflows, yielding mass loading factors below unity and implying these galaxies cannot sustain their current level of star-formation rates. These results are based on the T $\sim 10^4$ K photoionised gas phase traced by MgII; additional accreting/outflowing material in other gas phases may also be present, but remains undetected in this study. Quasar sightlines consistently show redshifted inflow components and blueshifted outflow components, demonstrating that ultra-strong MgII absorbers trace baryon cycling out to impact parameters of $D = 15$-31 kpc. Moreover, the unexpectedly high prevalence of inflows suggests that ultra-strong MgII absorbers offer a powerful strategy for future surveys to systematically map inflow and outflow cycles across cosmic time.

Sanna Gulati (NCRA-TIFR), Silpa Sasikumar (Universidad de Concepción), Preeti Kharb (NCRA-TIFR), Luis C. Ho (Peking University), Salmoli Ghosh (NCRA-TIFR), Janhavi Baghel (NCRA-TIFR)

We present results from uGMRT 685 MHz observations of 87 QSOs belonging to the Palomar Green (PG) quasar sample with $z<0.5$. Radio emission is detected in all sources except for 3 radio-quiet (RQ) sources, viz., PG 0043+039, PG 1121+422, and PG 1552+085. The radio-loud (RL) $-$ RQ dichotomy persists at 685 MHz with only 1 source, PG 1216+069, changing its classification from RQ to RL. Approximately 1/3 of the detected RQ quasars display AGN-dominated radio emission while the rest may show additional contributions from stellar-related processes. Consistent with this, the RL and RQ quasars occupy distinct tracks on the `fundamental plane' of black hole activity. We find that RL quasars have $\log_{10}(L_{685\,\mathrm{MHz}}/\mathrm{W\,Hz}^{-1}) > 25.5$, while RQ quasars have ${\log_{10}(L_{685\,\mathrm{MHz}}/\mathrm{W\,Hz}^{-1})} <23.5$. Furthermore, the radio sizes display the RQ$-$RL divide as well with RQ sources typically having sizes $\lesssim30$ kpc, with only 16 ($\sim22$%) RQ sources having sizes between 30 and 100 kpc where there is an overlap with RL quasar sizes. A strong correlation exists between 685 MHz radio luminosity and black hole mass which is tightened when accretion rate is considered, highlighting the important role played by the accretion rate and accretion disk structure in jet production. We found no difference in the minimum-energy magnetic field strengths of the radio cores of RL and RQ quasars; however, different assumptions of source volume and volume filling factors may apply. High-resolution X-ray observations and radio-X-ray flux comparisons are needed to independently test the `magnetic flux paradigm'.

Jihyun Kim, Dmitri Ivanov, Kazumasa Kawata, Hiroyuki Sagawa, Gordon Thomson (on behalf of the Telescope Array Collaboration)

The Telescope Array (TA) experiment, the largest observatory for ultra-high energy cosmic rays in the Northern Hemisphere, has identified two medium-scale anisotropies: the TA Hotspot near the constellation Ursa Major and an excess in the direction of the Perseus-Pisces supercluster. Studying these medium-scale anisotropies may provide insights into the origins of ultra-high energy cosmic rays. This presentation will explore an oversampling analysis of TA surface detector data to evaluate these medium-scale event excesses and will present the latest findings on the TA Hotspot and the Perseus-Pisces supercluster excess.

Jihyun Kim, Dmitri Ivanov, Gordon Thomson (on behalf of the Telescope Array Collaboration)

Ultra-high energy cosmic rays (UHECRs) are extremely energetic charged particles that originate from outer space. The Telescope Array (TA) experiment, the largest UHECR observatory in the Northern Hemisphere, has provided high-precision measurements of the cosmic ray energy spectrum due to its stable operation and efficient data collection. These measurements have revealed three significant spectral features: the ankle, shoulder, and cutoff. Analyzing these features is crucial for understanding the origin and propagation of UHECRs. In this talk, we will present the latest energy spectrum measured by the TA surface detectors and discuss the observed differences in the UHECR energy spectrum between the northern and southern skies.

Grzegorz Wiktorowicz, Matthew Middleton, Mirek Giersz, Adam Ingram, Adam McMaster, Abbas Askar, Lucas Hellström

Self-lensing (SL) represents a powerful technique for detecting compact objects in binary systems through gravitational microlensing effects, when a compact companion transits in front of its luminous partner. We present the first comprehensive study of SL probability within globular cluster (GC) environments, utilizing synthetic stellar populations from MOCCA simulations to predict detection rates for the Extremely Large Telescope (ELT). Our analysis incorporates finite-size lens effects for white dwarf (WD) lenses and the specific observational characteristics of the ELT/MICADO instrument. We find that present-day GCs contain 1-50 SL sources with magnifications $\mu_\mathrm{sl} > 1+10^{-8}$, strongly dependent on initial binary fraction, with systems dominated by WD lenses paired with low-mass main-sequence companions. The predicted populations exhibit characteristic bimodal magnitude distributions with peaks at $m \approx 24$ and 32 mag at 10 kpc distance, and typical Einstein ring crossing times of $\tau_\mathrm{eff} \sim 2$ hours. ELT observations should achieve detection efficiency of 0.015-10 sources in $\sim150$ nearby GC after a year of observations depending on distance and survey strategy, with nearby clusters ($D \lesssim 10$ kpc) offering the highest yields. Multi-year monitoring campaigns with daily cadence provide order-of-magnitude improvements over single observations through enhanced photometric precision and increased detection probability. Our results demonstrate that coordinated ELT surveys of Galactic GCs represent a viable approach for probing hidden binary populations and compact object demographics in dense stellar environments, with comprehensive programs potentially yielding up to 10-100 well-characterized SL sources after first 5 years of observations suitable for statistical studies of binary evolution in extreme environments.

We present wide-field upgraded Giant Metrewave Radio Telescope (uGMRT) images of the fields around the X-shaped radio-galaxies (XRGs) 4C32.25, 4C61.23, and MRC 2011-298 obtained at 400 MHz. The observations are calibrated using the extreme peeling method to account for direction-dependent effects across the field of view, as previously applied to Low-frequency array (LOFAR) data. Our 400 MHz images capture in fine detail the radio-morphology of the XRGs, as well as other serendipitous radio-sources located in these fields. We use these images along with archival low-frequencyand high-frequency radio data to investigate the spectral properties of the XRGs 4C32.25 and 4C61.23. Under the assumption of conditions corresponding to the maximum radio-source age, we estimate the spectral ages of both the primary lobes and the wings. These ages indicate that the wings are the oldest component of the XRGs and are a product of past radio activity. Moreover, we have used the radio images available to derive high-resolution spectral index maps for these two XRGs. We find that the spectral index steepens from the primary lobes towards the wings, consistent with our spectral age estimates. These results suggest that precessional and backflow models explain the X-shaped radio-morphology of 4C32.25 and 4C61.23, respectively. Finally, taking advantage of our wide-area images, we identify several serendipitous diffuse radio-sources located in our XRG fields and cross-reference them with previous surveys.

Jowita Borowska-Naguszewska, Robert Brose, Bernardo Cornejo, Jonathan Mackey, Robert Daniel Parsons, Fabian Schüssler (for the H.E.S.S. Collaboration)

Supernova (SN) explosions interacting with dense circumstellar medium are considered to be very promising sites for efficient cosmic-ray (CR) acceleration and subsequent emission of neutral-pion-decay gamma rays. These environments share similarities with already detected gamma-ray novae, but with much greater available energy content, so it is important to characterize their emission in the very-high-energy range. We present the results of H.E.S.S. observations of one such candidate source - SN 2024ggi, located in NGC 3621 at a distance of 7.24 Mpc. A total of 30 hours of data, gathered throughout a month of post-explosion observations, provide flux upper limits that are used to constrain source parameters, offering meaningful insights for theoretical predictions. We exclude bright gamma-ray emission in the first day after explosion, and later upper limits are consistent with wind densities derived from optical observations.

Xiaoyang Chen, Kohei Ichikawa, Masayuki Akiyama, Kohei Inayoshi, Akio K. Inoue, Masafusa Onoue, Yoshiki Toba, Jorge A. Zavala, Tom J. Bakx, Toshihiro Kawaguchi, Kianhong Lee, Naoki Matsumoto, Bovornpratch Vijarnwannaluk

One of the most remarkable discoveries of JWST is a population of compact, red sources at z > 4, commonly referred to as Little Red Dots (LRDs). Spectroscopic identifications reported that most LRDs are active galactic nuclei (AGNs), which are preferentially found around z~6 and could imply a key phase in the formation and growth of black holes (BHs) in the early universe. Photometric surveys at lower redshift have recently been carried out to trace their evolution across cosmic time, and a small number of LRDs have been spectroscopically identified at both Cosmic Noon and in the local universe. Here we report the discovery of one of the lowest-z analogs of LRDs, J204837.26-002437.2 (hereafter J2048) at z = 0.4332, using new Gemini-N/GMOS IFU observations combined with archival multi-band photometric SED data. The GMOS data reveal extended blue emission from starburst with a star formation rate of 400 Msun yr-1, together with an extended, highly fast ionized outflow. This is the first spectroscopic confirmation of extended host emission and outflow in an LRD-like galaxy, providing a unique laboratory for understanding the nature of their high-redshift counterparts. Moreover, J2048 would host an extremely overmassive BH with a BH-to-stellar mass ratio of 0.6, with the BH mass and host stellar mass estimated to be 10^10.2 and 10^10.4 Msun, respectively. We discuss the origin and evolutionary fate of J2048, and the implications that such low-z analogs have for interpreting the properties of high-z LRDs.

Tina Wach, Alison M. W. Mitchell (for the H.E.S.S. Collaboration)

Pulsar halos are a recently identified class of TeV $\gamma$-ray sources, offering valuable insights into the evolution of pulsar systems at the highest energies. However, only a handful of such sources have been detected so far, making each new identification critical for understanding the properties of the population as a whole. We report the first detection of extended very-high-energy (VHE) $\gamma$-ray emission around PSR~B1055$-$52 using observations from the H.E.S.S. array. This middle-aged pulsar, previously grouped together with Geminga and PSR~B0656$+$14 as part of the ``Three Musketeers'', has now been confirmed to host a TeV pulsar halo, making it the third detected system of its kind, and the first TeV pulsar halo discovered in the southern hemisphere. Our analysis performed in an energy range of $0.3-60\,$TeV, reveals gamma-ray emission with a one sigma extension of $(2.05 \pm 0.32)^\circ$. The analysis indicates that the emission extends beyond the region which was observed with H.E.S.S.. No significant spectral variation is detected across the emission. The diffusion coefficient derived for this halo is significantly lower than the standard ISM value, aligning with findings in the Geminga halo and indicating that slow diffusion may be a common property of pulsar halos. The detection of this new TeV pulsar halo provides a crucial data point for studying the population-wide properties of pulsar halos, their impact on cosmic-ray propagation, and their role as a source of Galactic electrons and positrons.

Gravitational lens flux ratio anomalies are a powerful probe of small-scale mass structures within lens galaxies. These anomalies are often attributed to dark matter subhalos, but the baryonic components of the lens can also play a significant role. This study investigates the impact of galactic bars, a common feature in spiral galaxies, on flux ratio anomalies. We conduct a systematic analysis using a sample of 21 barred galaxies from the high-resolution Auriga cosmological simulations. First, we model the projected mass distribution of these galaxies with the Multi-Gaussian Expansion formalism. This method yields smooth lens potentials that preserve the primary bar structure while mitigating numerical noise. We then perform strong lensing simulations and quantify the flux ratio anomalies by measuring their deviation from the theoretical cusp-caustic relation. To characterize the structural properties of the bars, we use a Fourier decomposition of the surface mass density in the bar region. Our primary finding is a strong, statistically significant correlation between the magnitude of the flux ratio anomaly and the strength of higher-order even Fourier modes. Specifically, the strengths of the boxy/peanut and hexapole components show an exceptionally tight correlation with the flux anomaly, with Spearman correlation coefficients of r=0.85 and 0.89, and p-values on the order of 1e-6 and 1e-8, respectively. This demonstrates that flux ratio anomalies are highly sensitive to the complex, non-axisymmetric features of galactic bars. We conclude that the flux ratio anomaly can be a powerful indicator of a galactic bar's complex morphology. Failing to account for a bar's complex morphology can lead to a misinterpretation of the lensing signature, potentially causing an overestimation of the dark matter subhalo population.

Iain M. Coulson, Yi-Jehng Kuan, Steven B. Charnley, Martin A. Cordiner, Yo-Ling Chuang, Yueh-Ning Lee, Min-Kai Lin, Stefanie N. Milam, Bannawit Pimpanuwat, Nathan X. Roth, Michał Żółtowski

We report the detection of HCN ($J=3-2$) rotational emission from comet 3I/ATLAS at a heliocentric distance of 2.13 AU with the James Clerk Maxwell Telescope (JCMT). Observations were conducted from 07 August 2025 (UT) using the $^{\prime}\overline U^{\prime}\overline u$ heterodyne receiver and ACSIS spectroscopic backend. The HCN line was detected at $>5\sigma$ on 14 Sep 2025 (UT) and a production rate of $Q({\rm HCN})=(4.0\pm1.7)\times10^{25}\ {\rm s}^{-1}$ was derived by non-LTE radiative transfer modelling. Preliminary estimates of the HCN/H$_2$O and CN/HCN abundance ratios suggest values similar to Solar System comets.

Pooja Devi, Ramesh Chandra, Rositsa Miteva, M. Syed Ibrahim, Kamal Joshi

Type II radio bursts are signatures of shock waves generated by solar eruptions, observed at radio wavelengths. While metric (m) type II bursts originate in the lower corona, their longer-wavelength (up to kilometers) counterparts extend into interplanetary space. A rare but valuable feature observed in some type II bursts is band splitting in their dynamic spectra, which provides crucial insights into physical parameters such as shock speed, Alfvén Mach number, Alfvén speed, and coronal magnetic field strength (B). In this study, we investigate band-splitting in 44 m-type II radio bursts observed by the Radio Solar Telescope Network during solar cycle 24 (2009 -- 2019). These events exhibit splitting in both fundamental and harmonic bands and are analyzed under both perpendicular and parallel shocks. All events are associated to solar flares and 41 (93 \%) with the coronal mass ejections. Shock speeds, derived using a hybrid coronal density model proposed by \cite{Vrsnak2004}, range from $\approx$ 350 to 1727 \kms. The relative bandwidth (BDW) of the split bands remains constant with frequency and height. Alfvén Mach numbers indicate moderate shock strength (1.06 -- 3.38), while Alfvén speeds and $B$ vary from $\approx$ 230 -- 1294 \kms\ and $\approx$ 0.48 -- 7.13 G, respectively. Power-law relationships are established as $BDW \propto f_L^{-0.4}$ and $BDW \propto R^{\sim1}$, while the coronal magnetic field decreases with height as $B \propto R^{\sim-3}$. These results enhance our understanding of shock dynamics and magnetic field structures in the solar corona.

Quasi-periodic fast propagating magnetosonic waves (QFPs) were discovered in the solar corona in EUV since the launch of SDO spacecraft more than a decade ago. The QFP waves are associated with flares and coronal mass ejections (CMEs) providing information on flare pulsations as well as on the magnetic field by MHD wave seismology. Previous models of QFP waves used primarily idealized magnetic active region structures. However, more realistic active region numerical models are needed to improve the application of coronal seismology to observations of waves in coronal structures. Here, we extend the previous models by including realistic magnetic configuration based on an observed coronal active region in a case study using AR 11166 observed on March 10, 2011 by SDO/AIA, using potential field extrapolation of photospheric magnetic field with realistic gravitationally stratified density structure { with typical coronal temperature} in our resistive 3D MHD model. We aim at reproducing the observed QFPs properties, such as directionality, propagation, reflection, nonlinearity, and damping of these waves. We model various forms of excitation of QFPs through time dependent boundary conditions, and localized pulses at the base of the corona. We produce synthetic emission measure (EM) maps from the 3D MHD modeling results to facilitate comparison to EUV observations. We find that the present more realistic model provides better qualitative agreement with observations compared to previous idealized models, improving the study of QFP wave excitation, propagation and damping in coronal ARs, with potential applications to coronal seismology.

Matteo Imbrogno, Andrea Sacchi, Giovanni Miniutti, Francesco Tombesi, Gian Luca Israel, Enrico Piconcelli, Roberta Amato

In the last few years, a few supermassive black holes (SMBHs) have shown short-term (of the order of hours) X-ray variability. Given the limited size of the sample, every new addition to this class of SMBHs can bring invaluable information. Within the context of an automated search for X-ray sources showing flux variability in the \textit{Chandra} archive, we identified peculiar variability patterns in 2MASX J12571076+2724177 (J1257), a SMBH in the Coma cluster, during observations performed in 2020. We investigated the long-term evolution of the flux, together with the evolution of the spectral parameters throughout the \textit{Chandra} and \textit{XMM-Newton} observations, which cover a time span of approximately 20 years. We found that J1257 has repeatedly shown peculiar variability over the last 20 years, on typical timescales of $\simeq20-25$ ks. From our spectral analysis, we found hints of a softer-when-brighter behaviour and of two well-separated flux states. We suggest that J1257 might represent a new addition to the ever-growing size of relatively low mass SMBHs ($M\simeq10^6-10^7\mathrm{M}_\odot$) showing extreme, possibly quasi-periodic X-ray variability on short time scales. The available dataset does not allow for a definitive classification of the nature of the variability. However, given the observed properties, it could either represent a quasi-periodic oscillation at particularly low frequency or be associated with quasi-periodic eruptions in an AGN with peculiar spectral properties.

We analysed the flickering of selected nova-like cataclysmic variables observed by the TESS satellite and XMM-Newton. We searched for break frequencies ($f_{\rm b}$) in the corresponding power density spectra (PDS), and for any long-term evolution. We found a new optical $f_{\rm b}$ in three nova-like systems and confirmed that the value of this frequency is clustered around 1 mHz. V504 Cen and V751 Cyg show possible X-ray counterparts of $f_{\rm b}$ that had previously only been seen in MV Lyr. This points towards the very central disc for source localisation. We investigated a previously proposed correlation between white dwarf mass and $f_{\rm b}$, but thanks to the new measurements we do not conclude its existence. V3885 Sgr and V1193 Ori show flaring activity in the long-term light curve during which TESS observations were made. The corresponding PDSs show changes in shape and disappearance of $f_{\rm b}$. TT Ari and SGRt 062340.2-265715 exhibit smooth changes in the long-term optical light curve, and the corresponding TESS observations show variable $f_{\rm b}$ during these changes. $f_{\rm b}$ is higher for lower brightness, which was seen only in MV Lyr so far.

Alison M. W. Mitchell, Lukas Grosspietsch, Tina Wach (for the H.E.S.S. Collaboration)

IC 443 is a well-known supernova remnant that stands out due to its interaction with a dense molecular cloud, creating a complex environment where shocks can efficiently accelerate particles to high energies. This makes it a key target for investigating the mechanisms of cosmic-ray acceleration and gamma-ray production, particularly in the context of supernova remnants as potential sources of PeV cosmic rays. This work presents a first analysis of the region as observed by H.E.S.S.. We detect extended very-high-energy gamma-ray emission from IC 443, consistent with previous observations by VERITAS and MAGIC. A multi-wavelength comparison incorporating data from Fermi-LAT, MAGIC, and VERITAS strongly supports a hadronic origin of the observed emission, and highlights the presence of relativistic protons interacting with the surrounding molecular cloud. These findings reinforce the role of IC 443 as a key laboratory for studying supernova remnants as cosmic-ray accelerators and their interaction with their surrounding mediums.

In this work we derived [K/Fe] and [Mg/Fe] abundance ratios for six stars of the old globular cluster NGC 1786 in the Large Magellanic Cloud. We employed high-resolution spectra acquired with the MIKE spectrograph mounted at the Magellan/Clay telescope. We found a clear Mg-K anticorrelation among the analyzed stars. In particular, the Mg-poor stars ([Mg/Fe] < 0.0 dex) are enriched by ~ 0.25 dex in [K/Fe] compared to the Mg-rich stars ([Mg/Fe] > 0.0 dex). This finding makes NGC 1786 the first globular cluster residing in an external galaxy in which such extreme chemical anomaly has been detected. The observed trend nicely agrees with those observed in Galactic globular clusters hosting Mg-poor stars, such as NGC 2808, and Omega Centauri suggesting that such chemical anomaly is an ubiquitous feature of old, massive, and metal-poor stellar systems and it does not depend on the properties of the parent galaxy in which the cluster formed. Also, Na-O and Mg-Al anticorrelations were detected among the stars of NGC 1786. The newly discovered Mg-K anticorrelation reinforces the idea that stars capable of activating the complete MgAl cycle are responsible for the observed chemical anomalies in these clusters. In this context, asymptotic giant branch stars seem to be a valuable model since they are able to produce K while depleting Mg. However, the precise and complete physics of this model remains a subject of debate.

M. D. Lepinzan, G. Lacopo, D. Goz, G. Taffoni, P. Monaco, P. J. Elahi, U. Varetto, M. Cytowski

In this work we present the porting to Graphics Processing Units (GPUs, using OpenMP target directives) and optimization of a key module within the cosmological {\pinocchio} code, a Lagrangian Perturbation Theory (LPT)-based framework widely used for generating dark matter (DM) halo catalogs. Our optimization focuses on a specific segment of the code responsible for calculating the collapse time of each particle involved in the simulation. Due to the embarrassingly parallel nature of this computation, it represents an ideal candidate for GPU offloading. As part of the porting process, we developed fully GPU-native implementations of both cubic spline and bilinear interpolation routines, required for evaluating collapse times. Since GNU Scientific Library (GSL) does not support GPU offloading, these custom implementations run entirely on the GPU and achieve residuals of only $\sim0.003\%$ when compared to the CPU-based implementation of GSL. Comparative benchmarking on the LEONARDO (NVIDIA-based) and SETONIX (AMD-based) supercomputers reveals notable portability and performance, with speedups of~\textit{4x} and up to~\textit{8x}, respectively. While collapse time calculation is not a primary bottleneck in the overall workflow, the acceleration reduces full production runs by $\sim 100$ seconds each leading to a cumulative saving of $\sim 160000$ Standard-h ($\sim28$ hours wall time) across thousands of simulations. Roofline analysis confirms that our GPU porting achieves over 80\% of the theoretical FP64 peak performance, confirming efficient compute-bound execution. This work demonstrates that OpenMP directives offer a portable, effective strategy for accelerating large-scale cosmological simulations on heterogeneous hardware.

E. Kalemci (1), M. Díaz Trigo (2), E. Oztaban (1), A. A. Abbasi (1), T. Stanke (3), J. A. Tomsick (4), T. J. Maccarone (5), A. Saraçyakupoğlu (1), E. von Nussbaum (6 and 7), J. C. A. Miller Jones (8), B. Bahçeci (1) ((1) Faculty of Engineering and Natural Sciences, Sabancı University, Istanbul, Turkey, (2) ESO, Garching bei München, Germany, (3) Max-Planck-Institut für Extraterrestrische Physik, Garching bei München, Germany, (4) Space Sciences Laboratory, University of California, Berkeley, USA, (5) Department of Physics &amp; Astronomy, Texas Tech University, Lubbock, USA, (6) Otto von Taube Gymnasium, Gauting, Germany, (7) Technische Universität München, Munich, Germany, (8) International Centre for Radio Astronomy Research - Curtin University, Perth, Australia)

We re-investigated the distance to the black hole X-ray binary 4U 1630-47 by analyzing its dust scattering halo (DSH) using high-resolution X-ray (Chandra) and millimeter (APEX) observations. Dust scattering halos form when X-rays from a compact source are scattered by interstellar dust, creating diffuse ring-like structures that can provide clues about the source's distance. Our previous work suggested two possible distances: 4.9 kpc and 11.5 kpc, but uncertainties remained due to low-resolution CO maps. We developed a new methodology to refine these estimates, starting with a machine learning approach to determine a 3D representation of molecular clouds from the APEX dataset. The 3D maps are combined with X-ray flux measurements to generate synthetic DSH images. By comparing synthetic images with the observed Chandra data through radial and azimuthal profile fitting, we not only measure the source distance but also distinguish whether the molecular clouds are at their near or far distances. The current analysis again supported a distance of 11.5 kpc over alternative estimates. While the method produced a lower reduced chi-squared for both the azimuthal and radial fits for a distance of 13.6 kpc, we ruled it out as it would have produced a bright ring beyond the APEX field of view, which is not seen in the Chandra image. The 4.85 kpc estimate was also excluded due to poor fit quality and cloud distance conflicts. The systematic error of 1 kpc, arising from uncertainties in determining molecular cloud distances, dominates the total error.

Low metallicity stellar populations are very abundant in the Universe, either as the remnants of the past history of the Milky Way or similar spiral galaxies, or the young low metallicity stellar populations that are being observed in the local dwarf galaxies or in the high-z objects with low metal content recently found with JWST. Our goal is to develop new high-spectral-resolution models tailored for low-metallicity environments and apply them to analyse stellar population data, particularly in cases where a significant portion of the stellar content exhibits low metallicity. Methods. We used the state-of-the-art stellar population synthesis code HR-pyPopStar with available stellar libraries to create a new set of models focused on low metallicity stellar populations. We have compared the new spectral energy distributions with the previous models of HR-pyPopStar for solar metallicity. Once we verified that the spectra, except for the oldest ages that show some differences in the molecular bands of the TiO and G band, are similar, we reanalysed the high resolution data from the globular cluster M 15 by finding a better estimate of its age and metallicity. Finally, we analysed a subsample of mostly star-forming dwarf galaxies from the MaNGA survey we found similar stellar mass-mean stellar metallicity weighted by light to other studies that studied star forming dwarf galaxies and slightly higher mean stellar metallicity than the other works that analysed all types of dwarf galaxies at the same time, but are within error bars.

R. D. Saxton, T. Wevers, S. van Velzen, K. Alexander, Z. Liu, A. Mummery, M. Giustini, G. Miniutti, F. Fuerst, J. J. E. Kajava, A. M. Read, P. G. Jonker, A. Rau, D.-Y. Li

We report here on observations of a tidal disruption event, XMMSL2 J1404-2511, discovered in an XMM-Newton slew, in a quiescent galaxy at z=0.043. X-ray monitoring covered the epoch when the accretion disc transitioned from a thermal state, with kT~80 eV, to a harder state dominated by a warm, optically-thick corona. The bulk of the coronal formation took place within 7 days and was coincident with a temporary drop in the emitted radiation by a factor 4. After a plateau phase of ~100 days, the X-ray flux of XMMSL2 J1404-2511 decayed by a factor 500 within 230 days. We estimate the black hole mass in the galaxy to be $M_{BH}=4\pm{2}\times10^{6}$ solar masses and the peak X-ray luminosity $L_{X}\sim6\times10^{43}$ ergs/s. The optical/UV light curve is flat over the timescale of the observations with $L_{opt}\sim 2\times10^{41}$ ergs/s. We find that TDEs with coronae are more often found in an X-ray sample than in an optically-selected sample. Late-time monitoring of the optical sample is needed to test whether this is an intrinsic property of TDEs or is due to a selection effect. From the fast decay of the X-ray emission we consider that the event was likely due to the partial stripping of an evolved star rather than a full stellar disruption, an idea supported by the detection of two further re-brightening episodes, two and four years after the first event, in the SRG/eROSITA all-sky survey.

V. P. Shyam Prakash, Vivek K. Agrawal, Rwitika Chatterjee, Radhakrishna Vatedka, Koushal Vadodariya, A. M. Vinodkumar

Scorpius X-1 is the brightest and first discovered X-ray source in the sky. Studying this source in the low-energy band has been challenging in the past due to its high brightness. However, with the X-ray SPECtroscopy and Timing (XSPECT) payload on-board Indias first X-ray Polarimetry Satellite (XPoSat), we have the capability to study the source despite its very high brightness, thanks to the fast (1 ms) readout of the instrument. We investigate the evolution of the spectral and timing properties of Sco X-1 across the horizontal, normal, and flaring branch, as observed with XSPECT. We examine changes in the spectral parameters as a function of position on the color-color diagram (CCD). Spectral studies indicate that the soft X-ray emission can be modeled using a multicolor disk component, with the inner disk temperature ranging from 0.6 to 0.8 keV. The hard component is described by a Comptonized continuum using either the nthComp or Comptb model with electron temperatures from 2.4 to 4.7 keV and optical depth between 5 and 14. Additionally, we observe the presence of an iron K-alpha line at 6.6 keV and an iron K-beta line at 7.6 keV. Both spectral models suggest a steep rise in Comptonization flux as well as disk flux in the flaring branch. An increase in neutron star blackbody temperature and inner disk temperature are also observed during flaring. The Z-track is driven by changes in the optical depth of the corona, the Comptonization flux and the disk flux and the inner disk temperature. No quasi-periodic oscillations are detected in any branch, suggesting their association with the high-energy spectrum.

Inorganic scintillators continue to be widely used within astrophysical X-ray and gamma-ray detectors. This is in part thanks to the development of new scintillators, such as GAGG:Ce, as well as the availability of new scintillator readout sensors such as Silicon Photomultipliers and Silicon Drift Detectors. In order to use such scintillator materials for spectrometry or polarimetry, a detailed understanding of their response is important. One parameter that can affect the scintillator performance, particularly at lower photon energies, is their Birks' coefficienct, which correlates the relative light yield to the ionization energy. While for many high-Z inorganic scintillators this effect can be ignored, for GAGG:Ce this appears to not be the case. Here we provide a measurement of the Birks' coefficient for GAGG:Ce using data from two different detectors irradiated in the 20-80 keV energy range at the LARIX-A X-ray beam in Ferrara, Italy. While the effects due to Birks' law are visible below 30 keV, they also significantly influence the performance of GAGG:Ce performance near one of the K-edges, affecting both the measured gain and the energy resolution. Here, we use beam test data to derive the Birks' coefficient from GAGG:Ce. The results indicate that for usage in hard X-ray and soft gamma-ray missions, this coefficient has a significant effect on the measurements.

Asteroseismology provides a direct observational window into the structure and evolution of stars. While spectroscopic and photometric methods only provide information about the surface properties of stars, asteroseismology, through the analysis of oscillation frequencies, offers comprehensive information about the deep stellar interior as well as the surface. The scattering of effective temperature (Teff) determined from the spectrum and degeneracy in the Hertzsprung Russell diagram poses challenges in developing a unique interior model for a single star. Although observational asteroseismic data partially lift this degeneracy, the best model that meets all asteroseismic constraints is not obtained. Most models reported in the literature typically address the large separation Dnu constraint between oscillation frequencies, which is a critical issue, especially in post main sequence stars. Reference frequencies, influenced by helium ionisation zone induced glitches in oscillation frequencies, are instrumental in refining models. Using the high metallicity derived from the colors of the Kepler Legacy star KIC 7747078, we obtain the masses of models M as 1.208 Msun and 1.275 Msun using the reference frequencies and individual frequencies as constraints, respectively. By applying the chi2 method using these reference frequencies, Dnu, and surface metallicity determined from the spectrum, we develop a unique star model with a mass of 1.171 pm 0.019 Msun, a radius of 1.961 pm 0.011 Rsun, an effective temperature of 5993 K, an initial metallicity of 0.0121, and an age of 5.15 pm 0.29 Gyr. A significant advantage of this method is that Teff emerges as an output, not a constraint. The mixed mode oscillation frequencies of this model align well with the observations.

Red giant stars play a key role in advancing our understanding of stellar mass loss. However, its initial mass and the amount of mass lost during this phase remain uncertain. In this study, we investigate the asteroseismic signatures of mass loss and the parameters that influence it. We examine six stars identified as red giant branch (RGB) stars in the APOKASC-2 catalog. Assuming these stars are on their first ascent of the RGB, we construct interior models. The resulting model ages are significantly older than the age of the Galaxy, indicating that these stars are likely experiencing mass loss and evolving toward the red clump (RC) phase. The minimum possible initial masses are estimated using the mass-metallicity diagram, from which we infer that the minimum mass lost by these stars ranges from $0.1$-$0.3{\rm M}_{\odot}$. Models constructed with an initial minimum mass yield the maximum possible age of the star. The ages of these models fall within the range of 9-9.5Gyr. For two stars, asteroseismic parameters confirm RC classification. Due to degeneracies in the HR diagram, distinguishing between internal structure models is challenging; however, asteroseismic constraints provide clear differentiation. Although mass-loss and mass-conservation models have similar $M$, $R$, and $T_{\rm eff}$ values, $\Delta\nu$s determined from the $l$=0 modes in the mass-loss models are 5-10$\%$ higher than observed. This discrepancy may arise from differences in internal structure. Finally, evolutionary model grids are used to examine how initial mass and $Z$ affect mass loss. Mass loss increases with increasing metallicity and decreases with increasing initial mass, regardless of the adopted value of $\eta$.

A. Tasa-Chaveli, Á. Sánchez-Monge, A. Fuente, A. Ginsburg, H. S. P. Müller, Th. Möller, P. Rivière-Marichalar, D. Navarro-Almaida, G. Esplugues, P. Schilke, M. Rodríguez-Baras, S. Thorwirth, L. Beitia-Antero

The recent detection of refractory molecules in massive star-forming regions provides a means of probing the innermost regions of disks around massive stars. These detections also make it possible to explore the chemical composition of refractories through gas-phase observations. In this regard, identifying refractory compounds containing sulfur could reveal potential connections between sulfur and refractories, as well as help determine the sulfur budget in these extreme environments. We find convincing evidence of a reliable detection of CaS, and tentative detections of KS and KSH in the disk G351.77-mm1. These are the first ever identifications of these species in the interstellar medium. The CaS, KS, and KSH column densities are about 3 orders of magnitude lower than those of the abundant sulfur compounds SO$_2$, CH$_3$SH and SiS, proving that these species are not the major reservoir of sulfur at the spatial scales probed by our observations. Higher angular resolution observations at different wavelengths are required to confirm these detections, which are of paramount importance to gain insights into the formation of gas-phase refractory molecules.

Alejandro Pascual Laguna, Victor Rollano, Aimar Najarro-Fiandra, David Rodriguez, Maria T. Magaz, Daniel Granados, Alicia Gomez

This work presents Ti/Al bi-layer Microwave Kinetic Inductance Detectors (MKIDs) based on lens-coupled spiral absorbers as the quasi-optical coupling mechanism for millimeter-wavelength radiation detection. From simulations, the lens-coupled absorbers provide a 70% lens aperture efficiency in both polarizations over an octave band with a spiral array absorber and over 10% relative bandwidth with a single spiral. We have fabricated and measured two devices with bare Ti/Al MKIDs: a 3x3 cm chip with 9 pixels to characterize the optical response at 85 GHz of the two variations of the absorber; and a large format demonstrator with 253 spiral-array pixels showing potential towards a large format millimeter-wavelength camera. We find a sensitivity of 1 mK/sqrt{Hz} and a detector yield of 95%.

P. Berczik, M. Ishchenko, O. Veles, M. Sobolenko, K. Voggel, C.M. Boily, E. Polyachenko, R. State

Context. A dual active galactic nucleus candidate with a separation of only 500 pc was recently found in NGC 7727. According to the hierarchical merging scenario, such objects would be expected to merge on a timescale of a few hundred Myr. However, estimating the accurate merging timescales for the two nuclei is still a complex challenge. Aims. Using our numerical N-body code, we can trace the full evolution of central black holes during all phases: dynamical friction of unbound black holes, binary black hole formation, hardening of the system due to two-body scattering, and emission of gravitational waves leading to the final merger. Methods. Our model has next components: the bulge contains two dense stellar nuclei, each of which hosts a black hole. The most massive black hole in the center of the galaxy has a mass of 1.54x10^8 Msol and the least massive black hole in the offset second stripped nucleus has a mass of 6.33x10^6 Msol. We followed the dynamical evolution of the system up to a final separation of four Schwarzschild radii. The black holes were added as special relativistic particles and their equation of motion contains a full post-Newtonian approximation - 2.5 term. Results. Initially, the black holes are not gravitationally bound and, thus, the system spends more than 60 Myr in the phase of dynamical friction while tightening the orbit. The two-body scattering phase takes place from 60 Myr up to 120 Myr. In the last 10 Myr, the black hole's separation is seen to be rapidly shrinking due to the gravitational wave emission. Starting from the physical separation observed today, the total merging time in our model is 130 (10) Myr. Conclusions. These results have implications for the statistics of strong sources of gravitational waves at low frequencies, namely, systems engaged in an advanced state of are expected to be prime sources for the LISA mission to observe.

Artificial Light At Night (ALAN) has been increasing steadily over the past century, particularly during the last decade. This leads to rising light pollution, which is known to have adverse effects on living organisms, including humans. We present a new software package to model light pollution from ground radiance measurements. The software is called Otus 3 and incorporates innovative ALAN diffusion models with different atmospheric profiles, cloud covers and urban emission functions. To date, light pollution modelling typically focused on calculating the zenith luminance of the skyglow produced by city lights. In Otus 3 we extend this and additionally model the horizontal illuminance on the ground, including the contributions from skyglow and the direct illumination. We applied Otus 3 to France using ground radiance data from the Visible Infrared Imaging Radiometer Suite (VIIRS). We calibrated our models using precise sky brightness measurements we obtained over 6 years at 139 different locations and make this dataset publicly available. We produced the first artificial illuminance map for France for the periods of 2013-2018 and 2019-2024. We found that the artificial ground illuminance in the middle of the night decreased by 23 % between these two periods, in stark contrast to the global trend.

The origin of ultra-high-energy cosmic rays, with energies $E \geq 10^{18}$ eV, remains unknown. Among the key observables used to investigate their nature are the energy spectrum, the arrival direction distribution, and the composition as a function of energy. The composition of the primary cosmic ray is inferred from properties of the extensive air showers they initiate, particularly from parameters sensitive to the primary mass. The most sensitive parameters to the primary mass are the atmospheric depth of the shower maximum, typically measured with fluorescence telescopes, and the muon content of the shower, measured using dedicated muon detectors. A commonly used observable in composition studies is the muon density at a fixed distance from the shower axis, derived by evaluating the reconstructed muon lateral distribution function (MLDF) at a reference distance. A specific type of muon detector features two acquisition modes: binary and integrator (commonly referred to as ADC mode, for Analog-to-Digital Converter). The binary mode allows for direct muon counting, while the ADC mode infers the muon number from the integrated signal of the detector response. Existing methods reconstruct the MLDF using data from either acquisition mode individually, or by combining both, but usually assigning a single mode per detector station in a given event. This work presents a novel method to reconstruct the MLDF based on a likelihood approach that simultaneously incorporates data from both acquisition modes at each detector station. We apply our method to the underground muon detectors of the Pierre Auger Observatory as a case study. However, this general approach can be applied to future detectors with dual acquisition capabilities. Our results demonstrate that the combined method outperforms traditional techniques that rely solely on either binary or ADC mode data.

Xiang Gao, Kai Li, Li-Heng Wang, Hai-bo Yuan, Hong-rui Gu, Ya-Ni Guo

M31, as the largest galaxy in the Local Group, is of significant importance for the study of stellar formation and evolution. Based on the data of 5,859 targets observed in M31 by Gu et al (\citeyear{2024ApJS..273....9G}), we selected 30 contact binaries by visual inspection for further study. Using the PHOEBE software and employing Bayesian optimization and Markov Chain Monte Carlo sampling, we determined the physical parameters of these 30 systems. The results show that 10 systems exhibit the O'Connell effect, which is well explained by introducing a dark spot on the primary star. 11 systems have mass ratios below 0.15, classifying them as extremely low mass ratio contact binaries, making them promising candidates for binary mergers. Six systems have primary star temperatures exceeding 10,000 K, classifying them as early-type contact binaries. The absolute physical parameters reveal that two contact binary systems contain massive stellar components, which may eventually evolve into compact binary star systems. To compare the effects of different galactic environments on the evolution of contact binaries, we constructed evolutionary diagrams for these 30 targets and for contact binaries in the Milky Way. The results show that, at the same mass, our targets have larger radii, higher luminosities, and lower orbital angular momenta than contact binaries in the Milky Way, indicating that they are at more advanced evolutionary stages. This may be attributed to the higher metallicity in M31 compared to the Milky Way.

Ivana Poljancic Beljan, Luka Sibenik, Tomislav Jurkic, Klaudija Loncaric, Rajka Jurdana-Sepic, Damir Hrzina, Werner Poetzi, Roman Brajsa, Astrid M. Veronig, Arnold Hanslmeier

We study solar differential rotation (DR) for solar cycle No. 19 (1954-1964) by tracing sunspot groups on the sunspot drawings of Kanzelhoehe Observatory for Solar and Environmental Research (KSO). Our aim is to extend previous DR analysis from the KSO data (1964-2016) to the years prior to 1964 to create a catalog of sunspot group positions and DR parameters from KSO sunspot drawings and white light images. Synodic angular rotation velocities were first determined using the daily shift (DS) and robust linear least-squares fit (rLSQ) methods, then converted to sidereal velocities, and used to derive solar DR parameters. We compare the DR parameters obtained from different sources and analyse the north-south asymmetry of rotation for solar cycle No. 19. It has been shown that our results for the equatorial rotation velocity (parameter A) and the gradient of DR (parameter B) coincide with earlier results from the KSO data (performed with a different method), as well as with results from the Kodaikanal Solar Observatory (KoSO) and the Yunnan Observatories (YNAO). In contrast, the values of parameter A from three different earlier studies based on the Greenwich Photoheliographic Results (GPR) exhibit statistically significant differences when compared to the values of parameter A derived from KSO, KoSO and YNAO. These findings suggest that the GPR data have the largest inconsistency compared to the other three data sources, highlighting the need for further analysis to identify the causes of these discrepancies. The analysis of the north-south asymmetry in the solar rotation profile using two different methods shows that the DR parameters of the hemispheres coincide, indicating a rotational symmetry around the equator. This is consistent with previous results from KSO and YNAO data. However, all sources indicate slightly higher equatorial rotation velocities in the southern hemisphere.

Jann Aschersleben, Dieter Horns, Emmanuel Moulin, Manuela Vecchi (for the H.E.S.S. Collaboration)

Intermediate mass black holes (IMBHs), with masses ranging from a hundred and a million solar masses, are hypothesised to be surrounded by dense regions of dark matter known as dark matter spikes, where the annihilation of dark matter particles could produce detectable gamma rays. The detection of dark matter annihilation around IMBHs therefore offers a promising approach for probing the nature of dark matter. In this work, we search for dark matter annihilation around IMBHs using data from the Galactic Plane Survey, the Extragalactic Survey and a selection of satellite galaxies observed by the H.E.S.S. gamma-ray experiment in Namibia. Since no evidence for a gamma-ray signal from dark matter annihilation around IMBHs has been found, we set upper limits on the velocity-weighted annihilation cross section for dark matter masses between 800 GeV and 100 TeV. Our analysis obtains limits on the velocity-weighted annihilation cross section below the thermal relic cross section for dark matter masses between 10 and 100 TeV.

About 12 percent of the early-type Be stars, so-called gamma Cas stars, exhibit an unusually hard and bright thermal X-ray emission that could result from accretion onto a white dwarf companion or from magnetic interactions between the Be star and its decretion disk. Exploring the full power of high-resolution X-ray spectroscopy of gamma Cas stars requires comparison of observations of the fluorescent Fe Kalpha emission lines near 6.4 keV with synthetic profiles of this line complex computed in the framework of the magnetic interaction and the accreting WD scenarios. For the latter, we further distinguish between accretion onto a non-magnetic and a magnetic WD. Our models account for different reservoirs of reprocessing material: the Be circumstellar decretion disk, the Be photosphere, an accretion disk around the WD companion, a magnetically channelled accretion flow and the WD photosphere. We find considerably different line properties for the different scenarios. For a non-magnetic accreting WD, the global Fe Kalpha complex is extremely broad, reaching a full width of 140 eV, whilst it is ~ 40 eV for the magnetic star-disk interaction and the magnetic accreting WD cases. In the magnetic star-disk interaction, the line centroid follows the orbital motion of the Be star, whereas it moves along with the WD in the case of an accreting WD. For gamma Cas, given the 15 times larger amplitude of the WD orbital motion, the shift in position for an accreting WD should be easily detectable with high-resolution spectrographs such as Resolve on XRISM, but remains essentially undetectable for the magnetic star-disk interaction. Upcoming high-resolution spectroscopy of the fluorescent Fe Kalpha emission lines in the X-ray spectra of gamma Cas stars will thus allow to distinguish between the competing scenarios.

Nícolas O. L. de Oliveira, Yolanda Jiménez-Teja, Renato A. Dupke, Eleazar R. Carrasco, Anton M. Koekemoer, Yuanyuan Su, Jose Manuel Vilchez, Jimmy A. Irwin, Eric D. Miller, Lucas E. Johnson

We present the analysis of the intracluster light (ICL) in three fossil groups (FG), RXJ085640.72+055347.36, RX J1136+0713, and RX J1410+4145, at z ~ 0.1. We used two optical broad-band filters, F435W and F606W, observed with the Hubble Space Telescope and spectroscopic data obtained with the Gemini Multi-Object Spectrograph to generate the ICL maps and measure the ICL fraction using CICLE, an algorithm developed to disentangle the ICL from the light of galaxies. We found ICL fractions of 9.9% - 14.4%, 3.8% - 6.1%, and 4.7% - 10.7% for RXJ0856, RXJ1136, and RXJ1410, respectively. This behavior is not consistent with the presence of the ICL fraction excess previously observed in merging clusters and also inconsistent with the constant ICL fraction distribution characteristic of relaxed systems, although the values found are within the typical range expected for the latter. Instead, they show a significantly increasing trend with wavelengths over ~ 3800 - 5500A, indicating that fossil groups are indeed old and undisturbed systems, even compared with regular relaxed clusters.

Gourab Giri, Christian Fendt, Joydeep Bagchi, Kshitij Thorat, D. J. Saikia, Roger P. Deane, Jacinta Delhaize

The persistence of radiative signatures in giant radio galaxies remains a frontier topic of research, with contemporary telescopes revealing intricate features that require investigation. This study aims to examine the emission characteristics of simulated GRGs, and correlate them with their underlying 3D dynamical properties. Sky-projected continuum and polarization maps at 1 GHz were computed from five 3D-RMHD simulations by integrating the synthesized emissivity data along the line of sight, with the integration path chosen to reflect the GRG evolution in the sky plane. The emissivities were derived from these RMHD simulations, featuring FR-I and FR-II jets injected from different locations of the large-scale environment. The jet-cocoon morphologies are strongly shaped by the triaxiality of the environment, resulting in features like wings and asymmetric cocoons, thereby making morphology a crucial indicator of GRG formation mechanisms. The decollimation of the bulk flow in GRG jets gives rise to intricate cocoon features, most notably filamentary structures-magnetically dominated threads with lifespans of a few Myr. High-jet-power cases frequently display enhanced emission zones at mid-cocoon distances (alongside warmspots around the jet-head), contradicting the interpretations of the GRG as a restarting source. In such cases, examining the lateral intensity variation of the cocoon may reveal the source's state, with a gradual decrease in emission suggesting a low-active stage. This study highlights that applying a simple radio power-jet power relation to a statistical GRG sample is unfeasible, as it depends on growth conditions of individual GRGs. Effects such as inverse-Compton CMB cooling and matter entrainment significantly impact the long-term emission persistence of GRGs. The diminishing fractional polarization with GRG evolution reflects increasing turbulence in the cocoon.

Auxiliadora Padrón-Brito, Natalia Arteaga-Marrero, Ian Cunnyngham, Jeff Kuhn

We propose a focal-plane wavefront sensor (FPWFS) based on a short multimode fiber (MMF) capable of operating under moderately broadband illumination. By coupling the aberrated focal-plane field into an MMF of length <1 cm, we preserve modal interference over a 10 nm bandwidth at near-infrared wavelengths. The resulting output intensity pattern encodes pupil phase information, enabling wavefront recovery via a neural network. Our approach resolves the inherent sign ambiguity of even pupil-phase aberrations and operates on millisecond timescales using readily available computing hardware, suitable for real-time adaptive optics. Unlike traditional pupil-plane sensors, the proposed FPWFS shares the optical path with the science beam, eliminating non-common-path aberrations by enabling simultaneous wavefront and focal-plane intensity retrieval. Its simplicity, compactness, sensitivity, and low cost make it an attractive candidate for next-generation astronomical instruments.

The theory of cosmic-ray (CR) penetration into dense molecular clouds developed recently for relativistic particles by Chernyshov et al. (2024) is extended to non-relativistic CRs. Interstellar CRs streaming into the clouds are able to resonantly excite MHD waves in diffuse cloud envelopes. This leads to the self-modulation, such that streaming particles are scattered at the self-generated waves. In contrast to relativistic CRs, transport of lower-energy particles in the envelopes is generally heavily affected by ionization losses; furthermore, both CR protons and electrons contribute to wave excitation. We show that these effects have profound impact on the self-modulation, and can dramatically reduce CR spectra even for clouds with moderate column densities of a few times $10^{21}$ cm$^{-2}$.

B. Vollmer (1), M. Soida (2), V. Heesen (3) ((1) CDS, Observatoire astronomique, Universite de Strasbourg, France, (2) Astronomical Observatory, Jagiellonian University, Poland, (3) Hamburg University, Hamburger Sternwarte, Germany)

In addition to the radio continuum emission of the thin galactic disk, vertically extended emission is ubiquitous in starforming disk galaxies. This halo emission can represent an important fraction of the total emission of the galaxy The cosmic ray electrons (CRe) responsible for the radio continuum emission are produced within the thin disk and transported into the halo. We made an attempt to reconstruct the radial properties of radio continuum halos in nearly edge-on galaxies where the star formation rate (SFR) distribution can be deprojected and the vertical radio continuum emission is well distinct from the disk emission. The deprojected SFR distribution is convolved with a Gaussian kernel to take CRe diffusion within the galactic disk into account and a vertical profile of the radio continuum emissivity is added to the disk emission. The three-dimensional emission distribution is then projected on the sky and compared to VLA radio continuum observations at 20 and 6 cm. We found that overall the halo emission contains information on the underlying distribution of the star formation rate. The majority of our galaxies show flaring radio continuum halos. Except for one galaxy, our Virgo galaxies follow the trend of increasing effective height with increasing radio continuum size found by the CHANG-ES collaboration. We confirm that radio continuum halos can represent a significant fraction of the total radio continuum emission of a starforming spiral galaxy. At 20 cm and 6 cm between 30 and 70 of the total radio continuum emission originate in the halo. We propose a halo classification based on the height ratio and SI between 20 and 6cm. If we interpret the vertical structures of the large-scale magnetic field within the disk-halo and halo types as a sign of a galactic outflow or wind, all galaxies except one most probably harbor an advection-dominated halo.

M. C. Bugueño, Facundo A. Gómez, Arianna Dolfi, Patricia B. Tissera

Understanding galaxy evolution is key to explaining the structures we observe in the present-day Universe. Counterrotating stellar disks (CRDs), i.e. co-spatial stellar disks rotating with opposite angular momentum, have been proposed as signatures of past accretion events. Therefore, they constitute potentially valuable tracers of galactic assembly. We aim to investigate the properties, formation, and significance of CRDs in a sample of Milky Way mass galaxies using the IllustrisTNG cosmological simulations. We select 260 central late-type galaxies (i.e. $M_{\rm tot} \approx 10^{12}$, $D/T>0.5$, $N_{\rm star}>10^5$). For each galaxy, we measure the circularity of its stellar particles and define the CRD by considering all particles with circularity $\epsilon < -0.7$, which are located within the spatial extension of the main disk. We then characterize the mass fraction, spatial extent, and star formation history of the CRDs. Out of the 260 galaxies, we find that 26 host significant CRDs (i.e. contributing at least 1\% of the total stellar mass of the disk). This means that CRDs are rare, consistent with the results from observations. We also find that the most of the CRDs are compact (i.e. 88\%), in-situ dominated (i.e.73\%), and exhibit bursty SFHs whose peaks often coincide with external perturbations. This means that external perturbations are able to catalyze star formation, even when a majority of the CRD's star population is in-situ. Finally, we find that a variety of formation pathways can lead to CRDs, including interaction-induced in-situ bursts and smooth accretion of misaligned gas. Overall, our results suggest that CRDs are rare but diverse in origin. In most cases, their formation is linked to the accretion of retrograde gas, either through mergers or environmental inflow, suggesting that these structures are sensitive tracers of the galaxy's past accretion history.

We show that the recently released B-mode polarisation data from the South Pole Telescope (SPT) favour a non-vanishing contribution of primordial gravitational waves of inflationary origin which is in tension with the previous BICEP-Keck (BK) measurements. Our analysis uses the third-order slow-roll primordial power spectra, with theoretically motivated priors, on the multifrequency SPT likelihoods complemented by the latest Planck satellite data products. The SPT measurements provide 1.0 bit of information gain on the first slow-roll parameter, which is higher than the 0.9 bit provided by BK even though the SPT sensitivity is five times lower. Moreover, the Bayesian dimensionality on the same parameter exceeds 1.5 for SPT versus 0.3 for BK showing that it is overconstrained by the SPT data. Even if this BB-tension could be the result of a yet to be understood foreground, our findings should motivate for a closer analysis of this unexpected B-modes excess.

Propagating nuclear uncertainties to nucleosynthesis simulations is key to understand the impact of theoretical uncertainties on the predictions, especially for processes far from the stability region, where nuclear properties are scarcely known. While systematic (model) uncertainties have been thoroughly studied, the statistical (parameter) ones have been more rarely explored, as constraining them is more challenging. We present here a methodology to determine coherently parameter uncertainties by anchoring the theoretical uncertainties to the experimentally known nuclear properties through the use of the Backward Forward Monte Carlo method. We use this methodology for two nucleosynthesis processes: the intermediate neutron capture process (i-process) and the rapid neutron capture process (r-process). We determine coherently for the i-process the uncertainties from the (n,$\gamma$) rates while we explore the impact of nuclear mass uncertainties for the r-process. The effect of parameter uncertainties on the final nucleosynthesis is in the same order as model uncertainties, suggesting the crucial need for more experimental constraints on key nuclei of interest. We show how key nuclear properties, such as relevant (n,$\gamma$) rates impacting the i-process tracers, could enhance tremendously the prediction of stellar evolution models by experimentally constraining them.

Pratyasha Gitika, Ryan M. Shannon, Matthew Bailes, Daniel J. Reardon, Matthew T. Miles, David J. Champion, Kathrin Grunthal

Pulsar timing arrays (PTAs) are Galactic-scale nanohertz-frequency gravitational wave (GW) detectors. Recently, several PTAs have found evidence for the presence of GWs in their datasets, but none of them have achieved a community-defined definitive (> 5$\sigma$) detection. Here, we identify limiting noise sources for PTAs and quantify their impact on sensitivity to GWs under different observing and noise modelling strategies. First, we search for intrinsic pulse jitter in a sample of 89 MSPs observed by the MeerKAT Pulsar Timing Array and obtain new jitter measurements for 20 MSPs. We then forecast jitter noise in pulsars for the future SKA-Mid telescope, finding that the timing precision of many of the best-timed MSPs would be dominated by jitter noise. We then consider dispersion measure variations from the interstellar medium and find that their effects are best mitigated by modelling them as a stationary Gaussian process with a power-law spectrum. Improving upon the established hasasia code for PTA sensitivity analysis, we assess the timing potential of the lower frequency UHF-band (544$-$1088\,MHz) of MeerKAT and find a potential increase in GW background sensitivity by $\approx 8$\%, relative to observing at L-band. We show that this improvement relies on assumptions on the propagation through the interstellar medium, and highlight that if observing frequency-dependent propagation effects, such as scattering noise, are present, where noise is not completely correlated across observing frequency, then the improvement is significantly diminished. Using the multi-frequency receivers and sub-arraying flexibility of MeerKAT, we find that focussed, high-cadence observations of the best MSPs can enhance the sensitivity of the array for both the continuous GWs and stochastic GWB. These results highlight the role of MeerKAT and the MPTA in the context of international GW search efforts.

Ray Garner III, Robert C. Kennicutt Jr, Laurent Drissen, Carmelle Robert, Laurie Rousseau-Nepton, Christophe Morisset, Philippe Amram, R. Pierre Martin, Emma Jarvis

Observing giant HII regions at fine spatial scales uncovers detailed structures and reveals variations in ionization, abundance, and dynamical properties of ionized gas and the effect of stellar feedback. Using emission line data of M33 observed with SITELLE as part of the Star-formation, Ionized Gas, and Nebular Abundances Legacy Survey (SIGNALS), we present maps of the principal optical emission line ratios for NGC 604, the most luminous HII region in M33. The excitation maps align well with the H$\alpha$ morphology and are clearly related to the location of the central stellar cluster and secondary stellar groups. The maps of ionization-sensitive line ratios show substantial variations across the face of NGC 604. We demonstrate that these variations are unlikely to be due to chemical inhomogeneities but are primarily caused by changes in ionization, which in turn affect the observed line ratios. We present the H$\alpha$ kinematics of the region and connect it to the excitation structure, showing how the dynamic motions influence the spatial distribution of ionized gas. We note two distinct sources identified in these excitation maps: a known supernova remnant and a previously unknown planetary nebula. Such parsec-scale features contribute only a small percentage to the overall light and would remain undetected without the use of high-resolution spatial data. Throughout the paper, we make comparisons to and raise concerns about single-aperture and long-slit spectroscopic measurements of giant HII regions, highlighting the limitations and potential inaccuracies of such methods.

Julián D. Alvarado-Gómez (1), Gaitee A. J. Hussain (2), Eliana M. Amazo-Gómez (1), Yu Xu (1 and 3), Katja Poppenhäger (1 and 4), Judy Chebly (1 and 5), Jean-François Donati (6), Beate Stelzer (7), Jorge Sanz-Forcada (8) ((1) Leibniz Institute for Astrophysics Potsdam, Germany (2) European Space Agency, The Netherlands (3) Peking University, China (4) Potsdam University, Germany (5) CNRS - Paris-Saclay, France (6) CNRS - IRAP, France (7) Eberhard Karls University Tübingen, Germany (8) CSIC-INTA, Spain)

We present a comprehensive investigation of the magnetic cycle of the young, active solar analogue $\iota$ Horologii ($\iota$ Hor) based on intensive spectropolarimetric monitoring using HARPSpol. Over a nearly three-year campaign, the technique of Zeeman-Doppler Imaging (ZDI) was used to reconstruct 18 maps of the large-scale surface magnetic field of the star. These maps trace the evolution of the magnetic field morphology over approximately 139 stellar rotations. Our analysis uncovers pronounced temporal evolution, including multiple polarity reversals and changes in field strength and geometry. We examine the evolution of the poloidal and toroidal field components, with the toroidal component showing strong modulation in concert with the chromospheric activity. Furthermore, for the first time, we reconstruct stellar magnetic butterfly diagrams which are used to trace the migration of large-scale magnetic features across the stellar surface, determining a magnetic polarity reversal timescale of roughly 100 rotations ($\sim773$ d). In addition, by tracking the field-weighted latitudinal positions, we obtain the first estimates of the large-scale flow properties on a star other than the Sun, identifying possible pole-ward and equator-ward drift speeds for different field polarities. These results provide critical insights into the dynamo processes operating in young solar-type stars and offer a direct comparison with the solar magnetic cycle.

Daniel Valentine, Hannah R. Wakeford, Mark Hammond, Ryan C. Challener, Billy Edwards, Theresa Lüftinger, Maximillian N. Günther

Eclipse mapping is a powerful tool for measuring 3D profiles of exoplanet atmospheres. To date, only JWST has been capable of widely applying this technique, but as a general observatory, it is too time-limited to conduct population-level mapping studies. Ariel, on the other hand, is a dedicated exoplanet mission set to observe 1000 transiting exoplanets, making it a natural candidate for this. To assess Ariel's mapping potential, we quantitatively benchmark its abilities against those of JWST using a simulation-and-retrieval framework with existing JWST eclipse maps as test cases. We find that for high-ranking targets, Ariel will be able to derive qualitatively similar maps to JWST using the same amount of observations; for mid-ranking targets, Ariel will be able to compete using as few as 3x as many observations; and for lower-ranking targets, the use of phase curves overcomes the need for an impractical number of repeated eclipse observations. We find that while Ariel is unlikely to have extensive latitudinal mapping abilities, it will have wide-ranging longitudinal abilities, from which the first-order atmospheric dynamics can be constrained. Using an analytically-derived metric, we determine the best eclipse mapping targets for Ariel, finding that it will be able to map nearly 100 targets using full phase curves in only quarter of its lifetime. This would be the largest mapping survey to date, and have enormous ramifications for our understanding of exoplanet atmospheric dynamics. Finally, we rank all the best mapping targets for both JWST and Ariel in order to encourage future eclipse mapping studies.

Sheng-Chieh Lin, Yuanyuan Su, Iraj Vaezzadeh, William Forman, Elke Roediger, Charles Romero, Paul Nulsen, Scott W. Randall, John ZuHone, Ralph Kraft, Christine Jones

The Virgo Cluster is the nearest cool core cluster that features two well-studied sloshing cold fronts at radii of $r \approx 30$ kpc and $r \approx 90$ kpc, respectively. In this work, we present results of XMM-Newton mosaic observations of a third, southwestern, cold front at a radius of $r \approx 250$ kpc, originally discovered with Suzaku. All three cold fronts are likely to be parts of an enormous swirling pattern, rooted in the core. The comparison with a numerical simulation of a binary cluster merger indicates that these cold fronts were produced in the same single event $-$ likely the infall of M49 from the northwest of Virgo and it is now re-entering the cluster from the south. This outermost cold front has probably survived for $2-3$ Gyr since the disturbance. We identified single sharp edges in the surface brightness profiles of the southern and southwestern sections of the cold front, whereas the western section is better characterized with double edges. This implies that magnetic fields have preserved the leading edge of the cold front, while its western side is beginning to split into two cold fronts likely due to Kelvin-Helmholtz instabilities. The slopes of the 2D power spectrum of the X-ray surface brightness fluctuations, derived for the brighter side of the cold front, are consistent with the expectation from Kolmogorov turbulence. Our findings highlight the role of cold fronts in shaping the thermal dynamics of the intracluster medium beyond the cluster core, which has important implications for cluster cosmology. Next-generation X-ray observatories, such as the proposed AXIS mission, will be ideal for identifying and characterizing ancient cold fronts.

Karim Sabri (1), Yves Gallant (1), Justine Devin (1), Kirsty Feijen (2) (for the H.E.S.S. collaboration, (1) Laboratoire Univers et Particules de Montpellier, Université de Montpellier, CNRS/IN2P3, (2) Université Paris Cité, CNRS, Astroparticule et Cosmologie)

Pulsar halos are a class of extended very-high-energy (VHE) sources highlighted by the HAWC observatory towards the Geminga pulsar and PSR B0656$+$14. These VHE sources are interpreted as the inverse Compton emission from electrons and positrons diffusing in the interstellar medium at an inhibited rate, having escaped the pulsar wind nebula. Our aim is to search for new pulsar halos using H.E.S.S. data and to constrain their physical properties. Using a physically-motivated model of pulsar halos, we created template-based models of the spatial and energetic distributions of the expected gamma-ray emission using the Gammapy library. A promising candidate source to which this model can be effectively applied is HESS J1831$-$098, an extended VHE source spatially coincident with two energetic pulsars, which also exhibits spectral continuity and morphological compatibility with the ultra-high-energy source 1LHAASO J1831$-$1007u*. It could be powered by the radio pulsar PSR J1831$-$0952 with a characteristic age of 128 kyr. We present a spectro-morphological analysis of this source with H.E.S.S. data, revealing that the emission is well described with a pulsar halo model, although we cannot reject a simple 2D Gaussian morphology. We discuss the implication of the derived physical parameters of the model.

We present a web-based application designed to simulate rotational light curves of small airless Solar System bodies under user-defined geometrical and physical conditions. The tool integrates both physical and empirical photometric models and enables users to input custom shape models, surface properties, and viewing geometries. A dedicated module also computes projected silhouettes at the epoch of stellar occultations, allowing direct comparison with observed chords. The application, developed in Python and Django, has been validated using well-characterized targets such as (136108) Haumea, (101955) Bennu, and (433) Eros, showing excellent agreement between synthetic and observed light curves and silhouettes. Beyond standard light curve simulations, the tool supports scenarios including surface heterogeneity, non-principal axis rotation (tumbling), and phase-angle effects. This flexible and accessible platform provides a powerful resource for interpreting photometric data, supporting ongoing observation campaigns, and aiding future mission planning.

This paper advances the concept maturity level (CML) of the Habitable Worlds Observatory (HWO) servicing architecture. Since servicing has occurred on other missions, this paper argues that the current CML is 2. To advance to CML 3, option spaces must be established for trade studies. We introduce the three space ages and the argument that we are on the cusp of a new revolutionary era. Servicing is only part of that coming change and the other elements of the future space age are introduced. The challenge of designing a flagship mission such as HWO is discussed. The value proposition for the adoption of a new technology, such as servicing HWO, is established. In the latter portion of the paper it is shown that these elements have promise of being beneficial to HWO and should be included in any trade space.

Madeline Lucey, Cecilia Mateu, Adrian Price-Whelan, David Hogg, Hans-Walter Rix, Robyn Sanderson

Understanding the formation and evolutionary history of the Milky Way requires detailed mapping of its stellar components, which preserve fossil records of the Galaxy's assembly through cosmic time. RR Lyrae stars are particularly well-suited for this endeavor, as they are old, standard candle variables that probe the Galaxy's earliest formation epochs. In this work, we employ a hierarchical Bayesian Gaussian Mixture Model (GMM) to characterize the three-dimensional density distribution of RR Lyrae stars in the Milky Way. This approach provides a flexible framework for modeling complex stellar distributions, particularly in the inner Galaxy where the bulge, disk, and halo components overlap. Our analysis reveals that the inner Galaxy is dominated by a distinct prolate stellar population with axis ratio $q$=1.30. Consistent with previous work, we find the halo follows a $r^{-4}$ power-law profile that flattens within 12 kpc of the Galactic center. We also confirm the halo is oblate ($q$=0.62) with a tilt angle of $12.22^{\circ}$. We report for the first time that this tilt aligns the halo major axis in the direction of the Sagittarius dwarf galaxy. These results establish GMMs as an effective and flexible tool for modeling Galactic structure and provide new constraints on the distribution of old stars in the inner Galaxy.

The equipartition model is widely used to estimate magnetic field strength from synchrotron intensity in radio galaxies, yet the validity of its underlying assumptions remains uncertain. Using an Arepo simulation which incorporates a two-moment cosmic ray (CR) transport scheme and a multiphase interstellar medium, we compare magnetic fields inferred from synthetic synchrotron emission maps with the true fields in the simulation. Starting from the derivation of the equipartition formula, we find that the deviation between the equipartition magnetic field and the true magnetic field depends only weakly on the ratio of the magnetic to the CR energy density. In practice, for both face-on and edge-on projections, the equipartition model slightly overestimates the total synchrotron-weighted magnetic field with mean offsets of 32% (0.17 dex) and 36% (0.2 dex), even though the energy equipartition does not hold locally. Beyond these average offsets, a clear trend emerges in edge-on projections that the model underestimates the field in the disk and overestimates it in the halo. Our results demonstrate that the validity of the equipartition model depends only weakly on the strict fulfillment of energy equipartition, and that the equipartition model remains a practical method for estimating magnetic field strengths in face-on projection maps based on our CR-magnetohydrodynamics simulation.

S. D. Bakshi, P. Barry, C. Bissolotti, I. Cloet, S. Corrodi, Z. Djurcic, S. Habib, K. Heitmann, T. J. Hobbs, W. Hopkins, S. Joosten, B. Kriesten, N. Ramachandra, A. Wells, M. Zurek

Progress in modern physics has been supported by a steadily expanding corpus of numerical analyses and computational frameworks, which in turn form the basis for precision calculations and baseline predictions in experimental programs. These tools play a central role in navigating a complex landscape of theoretical models and current and potential observables to identify and understand fundamental interactions in physics. In addition, efforts to search for new fundamental interactions increasingly have a cross-disciplinary nature, such that understanding and leveraging interoperabilities among computational tools may be a significant enhancement. This work presents a new agentic AI framework, which we call ArgoLOOM, designed to bridge methodologies and computational analyses across cosmology, collider physics, and nuclear science. We describe the system contours, key internal aspects, and outline its potential for unifying scientific discovery pipelines. In the process, we demonstrate the use of ArgoLOOM on two small-scale problems to illustrate its conceptual foundations and potential for extensibility into a steadily growing agentic framework for fundamental physics.

We compute relativistic Lindblad torques for circular, equatorial extreme-mass-ratio inspirals (EMRIs) embedded in relativistic thin accretion discs, including spinning black hole configurations. We find that relativistic effects can amplify the magnitude of these torques by orders of magnitude in the strong-field regime, and that the torque can even reverse direction as the EMRI approaches the innermost stable circular orbit (ISCO). However, we show that the location of this reversal is highly spin-dependent, shifting progressively closer to the ISCO, where gravitational-wave emission completely dominates the inspiral, as the spin of the central black hole increases. Spin also modifies the radial dependence of the Lindblad torques. We investigate whether Lindblad torques can be approximated by parametrised power laws of the form T_LR = A(r_s / 10M)^n_r (or combinations thereof), and find significant spin- and disc-dependent variations in the slope parameter n_r. For instance, for spin a/M = 0.9, we find n_r = 3.6 in the strong-field regime, compared to the Newtonian value of n_r = 4.5. Given current forecasts of parameter recovery for ``golden'', loud EMRIs in accretion discs (\Delta n_r ~ 0.5), we predict LISA could distinguish between different disc configurations through their relativistic Lindblad torque signatures, providing the first direct probe of the midplane structure of the inner region of accretion discs, which is inaccessible to electromagnetic observations.

At temperatures below the QCD phase transition, any substantial lepton number in the Universe can only be present within the neutrino sector. In this work, we systematically explore the impact of a non-vanishing lepton number on Big Bang Nucleosynthesis (BBN) and the Cosmic Microwave Background (CMB). Relying on our recently developed framework based on momentum averaged quantum kinetic equations for the neutrino density matrix, we solve the full BBN reaction network to obtain the abundances of primordial elements. We find that the maximal primordial total lepton number $L$ allowed by BBN and the CMB is $-0.12 \,(-0.10) \leq L \leq 0.13\,(0.12) $ for NH (IH), while specific flavor directions can be even more constrained. This bound is complementary to the limits obtained from avoiding baryon overproduction through sphaleron processes at the electroweak phase transition since, although numerically weaker, it applies at lower temperatures and is obtained completely independently. We publicly release the C++ code COFLASY-C on GitHub which solves for the evolution of the neutrino quantum kinetic equations numerically.

Gravitational waves (GWs) from compact binaries are excellent probes of gravity in the strong- and dynamical-field regime. We report a test of general relativity (GR) with the third GW Transient Catalog (GWTC-3) using the recently developed neural post-Einsteinian framework, both on individual events and at the population level through hierarchical modeling. We find no significant violation of GR and place a constraint that, for the first time, efficiently covers non-GR theories characterized by not only post-Newtonian deviations but also those beyond under the same theory-agnostic framework.

Upcoming near-infrared facilities (e.g., JWST/NIRCam, ELT/MICADO) will dramatically increase the detectability of galactic center Cepheids despite extreme extinction at optical wavelengths. In this work, we study the impact of dark matter (DM) annihilation on Cepheid stars in the inner parsec of the Milky Way. We show that at densities $\rho \sim 10^5 \, \text{GeV} \, \text{cm}^{-3}$, blue-loop evolution can be suppressed, preventing the formation of low-mass ($3$-$6 \, M_\odot$) short-period ($1$-$6$ days) Cepheids. A dearth of such variables could provide indirect evidence for DM heating. Notably, this effect occurs at lower DM densities than required to impact main-sequence stars. Future surveys will thus offer a novel, complementary probe of DM properties in galactic nuclei.

A fast-rolling axion can transfer its kinetic energy to gauge fields via the Chern-Simons coupling, leading to copious production of gauge quanta during inflation. The amplified gauge fields act as a source for both scalar and tensor perturbations. In this work, we propose a mechanism for suppressing scalar perturbations while sourcing strong tensor perturbations. We present an implementation of such a mechanism, demonstrating that sourced tensor perturbations are expected to be detected by upcoming next-generation CMB experiments.

Weakly-modelled searches for gravitational waves are essential for ensuring that all potential sources are accounted for in detection efforts, as they make minimal assumptions regarding source morphology. While these searches primarily target generic transient sources, they are also highly effective at identifying a broad range of compact binary coalescences, demonstrated by the weakly-modelled search algorithm coherent WaveBurst being the first to detect GW150914. Despite their ability to detect compact binaries with diverse properties, the accurate estimation of source parameters from their output remains to be a challenging task. To overcome this, we leverage physics-informed neural networks, which serve as a powerful tool for parameter estimation by applying physical constraints through the universal differential equation governing a compact binary system. With this approach, we rapidly infer the mass parameters of binary black hole merger systems to within 7% from only the time-frequency representation of the gravitational wave signal.

Upcoming astronomical surveys will produce petabytes of high-resolution images of the night sky, providing information about billions of stars and galaxies. Detecting and characterizing the astronomical objects in these images is a fundamental task in astronomy -- and a challenging one, as most of these objects are faint and many visually overlap with other objects. We propose an amortized variational inference procedure to solve this instance of small-object detection. Our key innovation is a family of spatially autoregressive variational distributions that partition and order the latent space according to a $K$-color checkerboard pattern. By construction, the conditional independencies of this variational family mirror those of the posterior distribution. We fit the variational distribution, which is parameterized by a convolutional neural network, using neural posterior estimation (NPE) to minimize an expectation of the forward KL divergence. Using images from the Sloan Digital Sky Survey, our method achieves state-of-the-art performance. We further demonstrate that the proposed autoregressive structure greatly improves posterior calibration.

In astrophysical shear flows, the Kelvin-Helmholtz (KH) instability is generally suppressed by magnetic tension provided a sufficiently strong streamwise magnetic field. This is often used to infer upper (or lower) bounds on field strengths in systems where shear-driven fluctuations are (or are not) observed, on the basis that fluctuations cannot grow in the absence of linear instability. On the contrary, by calculating the maximum growth that small-amplitude perturbations can achieve in finite time for such a system, we show that perturbations can grow in energy by orders of magnitude even when the flow is sub-Alfvénic, suggesting that shear-driven turbulence is possible even in the presence of strong magnetic fields, and challenging inferences from the observed presence or absence of shear-driven fluctuations. We further show that magnetic fields introduce additional nonmodal growth mechanisms relative to the hydrodynamic case, and that 2D simulations miss key aspects of these growth mechanisms.