UchUchU

研究動向

宇宙工学・惑星科学・宇宙物理の最新プレプリント。

astro-ph.SR

The B-Index as a Diagnostic of Cool Stars: Assessing Metallicity Dependence of TiO Absorption in the Visible Spectrum

Fatemeh Azizi, Mohammad Taghi Mirtorabi, Zahra Mohammadian

Molecular absorption features constitute essential diagnostics of late-type stellar atmospheres, with titanium oxide (TiO) bands serving as sensitive tracers of effective temperature and magnetic activity. While near-infrared TiO indices are well established, visible-band diagnostics provide complementary constraints for stellar classification and parameter estimation. This study investigates the metallicity dependence of the B-index, a TiO absorption measure centered at 567 nm, through syntheti…

詳細を見る →
astro-ph.IM

Aether.jl : A High-Performance 3D MHD and Multifluid Dust Code Written in a Dynamic Language with an Interactive Human-AI Development Framework

Ka Wai Ho

We present Aether.jl, a new finite-volume code for compressible hydrodynamics and magnetohydrodynamics, written in Julia and primarily designed for GPU systems. The code solves the MHD equations with constrained transport in Cartesian, cylindrical, and spherical-polar coordinates, using standard high-order Godunov methods. An arbitrary number of dust fluids can be coupled to the gas through stiff mutual drag. It was developed from scratch with interactive Human-coding agent workflow; the paper d…

詳細を見る →
astro-ph.IM

$\texttt{Aether.jl}$ : A High-Performance 3D MHD and Multifluid Dust Code Written in a Dynamic Language with an Interactive Human-AI Development Framework

Ka Wai Ho

We present $\texttt{Aether.jl}$, a new finite-volume code for compressible hydrodynamics and magnetohydrodynamics, written in Julia and primarily designed for GPU systems. The code solves the MHD equations with constrained transport in Cartesian, cylindrical, and spherical-polar coordinates, using standard high-order Godunov methods. An arbitrary number of dust fluids can be coupled to the gas through stiff mutual drag. It was developed from scratch with interactive Human-coding agent workflow;…

詳細を見る →
astro-ph.IM

$\texttt{Aether.jl}$ : A High-Performance 3D MHD and Multifluid Dust Code Written in a Dynamic Language with an Interactive Human-AI Development Framework

Ka Wai Ho

We present $\texttt{Aether}$, a new finite-volume code for compressible hydrodynamics and magnetohydrodynamics, written in Julia and primarily designed for GPU systems. The code solves the MHD equations with constrained transport in Cartesian, cylindrical, and spherical-polar coordinates, using standard high-order Godunov methods. An arbitrary number of dust fluids can be coupled to the gas through stiff mutual drag. It was developed from scratch with interactive Human-coding agent workflow; the…

詳細を見る →
astro-ph.SR

High-order Paschen emission from the quiet-Sun off-limb chromosphere

Haocheng Yu, Yukio Katsukawa, Mingde Ding, Takuma Matsumoto, Sami K. Solanki, Julian Blanco Rodríguez, David Orozco Suárez, Masahito Kubo et al.

We report the detection of high-order hydrogen Paschen emission lines (Pa~15, Pa~16, and Pa~17) in the quiet-Sun chromosphere off the solar limb using the Chromospheric Infrared SpectroPolarimeter (SCIP) on board the {\sc Sunrise~iii} balloon telescope. These lines reveal thread-like structures resembling spicules and exhibit systematically smaller Doppler velocities than Ca~II~854.2~nm, suggesting that they are optically thinner and more affected by line-of-sight averaging, especially near the…

詳細を見る →
astro-ph.GA

The galaxies' energy balance problem solved

C. J. Inman, C. C. Popescu, D. Murphy

We attempt to resolve the long-standing energy balance problem encountered by Radiative Transfer (RT) models, particularly in edge-on galaxies by incorporating a treatment for the clumpy structure of the Interstellar Medium (ISM). A subgrid approach is adopted, treating the quiescent dust clouds as pseudo-dust grains, with equivalent optical and thermal emission properties. Deriving key quantities such as the absorption, scattering and extinction cross-sections enables the virtualisation of the…

詳細を見る →
astro-ph.GA

The SAMI Galaxy Survey: Linking Tidal Features and Orbit Populations Using Schwarzschild Modelling

T. H. Rutherford, J. van de Sande, S. M. Croom, A. Fraser-McKelvie, G. Santucci, G. van de Ven, S. M. Sweet, S. Brough et al.

The evolution of angular momentum in galaxies is shaped by a combination of internal secular processes and external mechanisms such as mergers. Orbit-superposition based dynamical modelling provides a powerful means of linking the intrinsic orbital structures of galaxies to their global properties and merger histories. We construct Schwarzschild orbit-superposition models of massive ($\log(M/M_{\odot})>10$) SAMI galaxies using the DYNAMITE code, utilising deep KiDS photometry to accurately repro…

詳細を見る →
astro-ph.HE

Detection of possible burst oscillation in the neutron star low-mass X-ray binary 4U 1323-62

Manoj Mandal, Sachindra Naik

Burst oscillations observed during thermonuclear X-ray bursts arise from asymmetric brightness patterns on the neutron star surface and provide a direct probe of the neutron star spin frequency. We present a detailed timing analysis of the neutron star low-mass X-ray binary 4U 1323-62 using 2024 observations with XMM-Newton and NuSTAR observatories. We identify nine thermonuclear X-ray bursts in the XMM-Newton/EPIC-pn data, along with eclipsing dips in the light curve. One of the XMM-Newton burs…

詳細を見る →
astro-ph.HEastro-ph.SR

X-ray Activity of the RS CVn-type Star σ Gem with the First-Year Observations of Einstein Probe

Xuan Mao, Giuseppina Micela, Fabio Favata, Weimin Yuan, He-yang Liu, Huaqing Cheng

Context. Stellar flares are energetic events driven by the sudden release of magnetic energy in the stellar atmosphere. Studying these flares is crucial for understanding their impact on exoplanets, the circumstellar environment, and stellar evolution itself. The launch of the Einstein Probe (EP) offers a unique opportunity to systematically detect such events. Aims. We present a systematic analysis of the flaring activity of the active RS CVn-type binary σ Gem, utilizing the first-year monitori…

詳細を見る →
astro-ph.GA

How mergers shape galaxy morphology in the IllustrisTNG simulation

Guangquan Zeng, Lan Wang, Liang Gao

How galaxy mergers drive morphological evolution remains an open question. Traditional views hold that major mergers produce elliptical galaxies, while minor mergers form dispersion-dominated components such as galactic bulges. However, more recent work has challenged this simple picture, suggesting a more complex evolutionary scenario. In this study, we use the IllustrisTNG cosmological simulation to investigate how mergers shape galaxy morphology, across a broad range of galaxy masses and merg…

詳細を見る →
astro-ph.IMastro-ph.HE

On the Acceleration of Pulsar Timing computations using Normalising Flows and Parallelisation

Churchil Dwivedi, Hiya Shah, Hemanga Tahbildar

Single-Pulsar Noise Analysis (SPNA) and Gravitational Wave (GW) searches done on Pulsar Timing Array (PTA) datasets have everlastingly suffered from the computational bottleneck arising due to high dimensionality and multi-modality of the PTA likelihood landscape, along with strong correlations amongst various single-pulsar noises and ensemble-level common noise processes. We addressed this outstanding issue by employing a Normalising Flow-based Preconditioned Monte-Carlo sampling technique impl…

詳細を見る →
astro-ph.SR

Evidence for Dynamical Filtering: High Binary Fraction, Hard-binary Excess, and Unresolved Triples in the Surviving Core of NGC 6791

Huanbin Chi, Zhi Li, Feng Wang, Xuefen Tian, Linfeng Chang, Hongbo Liu, Yiqin Liu

We present a deep photometric analysis of the main-sequence (MS) population in the old, metal-rich open cluster (OC) NGC 6791 using Gaia Data Release 3 data. After correcting for differential reddening, we use the Bayesian model comparison to test whether stellar rotation can account for the observed MS broadening and find that a rotation-dominated interpretation is strongly disfavored. We therefore infer that unresolved multiplicity is the primary contributor to the photometric offsets. We deri…

詳細を見る →
astro-ph.SRastro-ph.EPastro-ph.GA

A chemo-dynamical search for planet-candidate hosts of possible extragalactic origin

Sun Tiancheng, Chen Xunzhou, Xiang Maosheng, Zhou Jianzhao, Lu Zixuan

To date, all known exoplanetary systems have been identified around stars currently residing in the Milky Way, whereas planets formed in external galaxies remain largely unexplored. Such systems would offer a unique probe of planet formation in galactic environments distinct from the Milky Way. We combine a literature-compiled sample of Kepler, K2, and TESS planet-candidate host stars with Gaia DR3 astrometry and radial velocities, and incorporate metallicities and [Mg/Fe] abundances from the LA…

詳細を見る →
astro-ph.IM

Enhancing the performance and capabilities of the MIRI instrument on JWST

S. Kendrew, M. Engesser, K. Rowlands, A. Noriega-Crespo, M. Decleir, H. Diamond-Lowe, M. Regan, J. Aguilar et al.

MIRI, the Mid-Infrared Instrument on the James Webb Space Telescope, is the only instrument sensitive to wavelengths longward of 5 um on the observatory. In this regime, MIRI brings order-of-magnitude improvements over past instruments and missions in a wavelength range that is challenging or impossible to access from the ground. As such, MIRI occupies a unique parameter space, offering unparalleled capabilities in all areas of astrophysics, from the Solar System to the most distant galaxies in…

詳細を見る →
physics.ao-phastro-ph.EPphysics.geo-phphysics.space-ph

Altitude-Dependent Near-Source Spectral Filtering of Meteor Infrasound Above 80 km and Consequences for Period-Based Energy Estimates

Elizabeth A. Silber, Igor P. Chunchuzov, Oleg E. Popov, Sergey N. Kulichkov

Infrasound signal period is widely used as a proxy for source energy in bolide studies, but the reliability of period-yield relations for small, high-altitude regional meteors has not been systematically evaluated. We analyze 90 infrasound detections from well-constrained regional meteoroid events (source altitudes 20-111 km, ranges 47-268 km) and demonstrate a strong, monotonic decrease in receiver dominant frequency with increasing source altitude (Spearman r_{s} = -0.629, p = 3.3 x 10^11). No…

詳細を見る →
astro-ph.IMphysics.ins-det

CCAT: a two-octave 1.024 GHz KID readout featuring an overlap-channel polyphase synthesis filter bank on RFSoC

Ruixuan, Xie, Adrian K. Sinclair, James Burgoyne, Maxwell Chapman, Scott Chapman, Steve K. Choi, Anthony I. Huber et al.

Next-generation submillimeter instruments require gigahertz-scale readout bandwidths to support the growing detector counts of large microwave kinetic inductance detector (KID) arrays. Designed to meet the readout bandwidth and tone-capacity requirements of the CCAT Prime-Cam 850 GHz and 410 GHz instrument modules, we developed our second-generation (Gen2) KID readout system on a Xilinx ZCU111 radio frequency system-on-chip (RFSoC), based on a parallelized overlap-channel polyphase synthesis fil…

詳細を見る →
astro-ph.GA

Energy Partitioning in Dust-catalyzed $\mathrm{H_2}$ and HD Formation Revealed by Molecular Simulations Considering Nuclear Quantum Effects

Xiaolong Yang, Lile Wang, Di Li, Shenzhen Xu

Molecular hydrogen formation on interstellar dust grains is a key surface process in the interstellar medium, but the redistribution of the recombination energy between the substrate and the nascent molecule remains poorly understood. Here, we use ring-polymer molecular dynamics (RPMD) with a machine-learning force field to investigate energy partitioning during $\mathrm{H_2}$ and $\mathrm{HD}$ formation on graphene at $T=25, 50$ and $100 \mathrm{K}$. We focus on the chemisorbed-H recombination…

詳細を見る →
astro-ph.HE

Time-dependent multi-energy neutrino emission from symbiotic recurrent novae: the role of accretion disks

Rui Xu, Yudong Cui, Yihan Shi, Lili Yang

Symbiotic recurrent novae provide a unique laboratory for studying thermonuclear explosions, shock evolution, and nonthermal particle acceleration in dense circumstellar environments. In this work, we develop a time-dependent, multi-energy framework to describe neutrino emission from such systems, consistently incorporating both MeV neutrinos produced during thermonuclear runaway and GeV neutrinos generated through hadronic interactions in nova-driven shocks. Using RS Oph as a benchmark source,…

詳細を見る →
astro-ph.SR

H-$α$ Integral Carrington Synoptic Maps Produced by NSO/NISP

K. J. Shuman, L. Bertello, O. Burtseva, A. A. Pevtsov

Monitoring long-term chromospheric activity and large-scale solar structures like filaments and plages is critical for understanding solar magnetic cycles and predicting space-weather events. While photospheric magnetic fields are routinely mapped, a consistent, global reference for chromospheric structures has been absent from H-$α$ observations. This technical report provides a comprehensive description of the methodology used to construct the NSF Global Oscillations Network Group (GONG) H-$α$…

詳細を見る →
astro-ph.IM

Performance Analysis of the Asgard/NOTT Nulling Interferometer: Optimizing Observing Modes for High-contrast Detection

J. P. Scott, S. Ertela, T. A. Stuber, D. Defr`ere, R. Laugier, J. C. Augereau, P. Chingaipe, G. Garreau et al.

We evaluate the performance of three beam-combination schemes, single-Bracewell, asymmetric dual-Bracewell, and symmetric dual-Bracewell, for the forthcoming Asgard/NOTT nulling interferometer at the Very Large Telescope Interferometer. Utilizing the SCIFYsim end-to-end simulator, we assess the instrument's performance by deriving the precision of calibrated null measurements as a function of stellar magnitude and simulating observations of varying hot exozodiacal dust (HEZD) distributions and a…

詳細を見る →
astro-ph.IM

Performance Analysis of the Asgard/NOTT Nulling Interferometer: Optimizing Observing Modes for High-contrast Detection

J. P. Scott, S. Ertel, T. A. Stuber, D. Defrère, R. Laugier, J. C. Augereau, P. Chingaipe, G. Garreau et al.

We evaluate the performance of three beam-combination schemes, single-Bracewell, asymmetric dual-Bracewell, and symmetric dual-Bracewell, for the forthcoming Asgard/NOTT nulling interferometer at the Very Large Telescope Interferometer. Utilizing the SCIFYsim end-to-end simulator, we assess the instrument's performance by deriving the precision of calibrated null measurements as a function of stellar magnitude and simulating observations of varying hot exozodiacal dust (HEZD) distributions and a…

詳細を見る →
astro-ph.GA

The CMZ Asymmetries: Feeding or Feedback?

John Bally

Three-fourths of the dense gas and dust in the CMZ is located at positive longitudes and positive radial velocities. The majority of compact 24 micrometer wavelength sources are at negative longitudes. These two asymmetries indicate either a recent asymmetric injection of gas along the bar dust lanes, or that most of the molecular gas is contained in a small number of massive, gravitationally bound clouds, or a major feedback episode which dissociated an entire sector of the CMZ's dense gas.

詳細を見る →
astro-ph.IM

MORFEO control strategy

Guido Agapito, Lorenzo Busoni, Cédric Plantet, Giulia Carlà, Alfio Puglisi, Jean-Pierre Véran, Marco Falotico, Gabriele Umbriaco et al.

The ESO Extremely Large Telescope (ELT) will offer unprecedented sensitivity and resolution in the near-infrared, marking a new era for ground-based astronomy. Among its key imaging instruments is MORFEO coupled with MICADO. MORFEO (Multi-conjugate adaptive Optics Relay For ELT Observations), formerly known as MAORY, is the largest astronomical adaptive optics system ever designed. It features 12 wavefront sensors and three deformable mirrors, for a total of over 20,000 subapertures and over 6,0…

詳細を見る →
astro-ph.GA

Old Disks Die Hard: How Does AGN Feedback Suppress Disk Formation in Milky Way Mass Galaxies?

Patricia Fofie, James S. Bullock, Sarah Wellons, Jorge Moreno, Francisco J. Mercado, Andrew Wetzel

The connection between a galaxy's visual shape and its star formation rate is one of the oldest established trends in galaxy evolution, yet the origin of this trend remains unsettled. We analyze two Milky-Way mass halos simulated with FIRE-2 galaxy formation physics, each run without AGN and with up to three implementations of AGN feedback. We use them to study how and why AGN star formation suppression affects morphological evolution over cosmic time. Both runs without AGN feedback produce prom…

詳細を見る →
astro-ph.HE

The second Arcminute Microkelvin Imager -- Large Array Gamma-ray burst radio afterglow catalog

L. Rhodes, D. Ibrahim, N. Sqalli, G. E. Anderson, R. Fender, A. J. van der Horst, J. S. Bright, A. K. Hughes et al.

Radio observations of gamma-ray burst afterglows provide insight in to the different emitting regions within the jet, its hydrodynamics and burst environment. In this paper, we present the second iteration of the Arcminute Microkelvin Imager - Large Array (AMI-LA) Gamma-ray burst (GRB) radio afterglow catalog. The catalog consists of 1035 observations of 210 bursts. Our observations range from 0.04 to 900days post-burst. We detect radio emission associated with 19 events with flux densities span…

詳細を見る →
astro-ph.HE

High-Energy Neutrinos from Supernova Shock Breakouts in Circumstellar Media: Light Curves, Spectra, and Contribution to the Extragalactic Neutrino Background

Tal Wasserman, Eli Waxman, Kohta Murase

Enhanced mass loss from core-collapse supernova (SN) progenitors shortly before explosion appears to be common, creating a compact, optically thick circumstellar medium (CSM) at $\sim10^{14}-10^{15}$ cm. We derive an analytic description of the light curves and spectra of high-energy neutrinos emitted by nonrelativistic SN shock breakouts through such CSM, as a function of shock velocity and CSM parameters, accounting for the evolution of the hydrodynamic structure and the electromagnetic (EM) s…

詳細を見る →
astro-ph.GAastro-ph.CO

Abundant Heavy Black Hole Seeds from Moderate Lyman-Werner Radiation

Ryan Hazlett, Eli Visbal, Greg L. Bryan, Mihir Kulkarni

The existence of high-redshift quasars may indicate that massive black hole seeds formed via supermassive Population III stars in atomic-cooling halos with large gas inflow rates; however, the dependence of this process on halo assembly rate and radiative background remains poorly constrained. We present a large suite of 65 high-resolution cosmological zoom-in simulations of 15 pristine halos spanning a wide range of Lyman-Werner radiation backgrounds and halo assembly histories. We introduce a…

詳細を見る →
astro-ph.HEastro-ph.GAastro-ph.SR

No Evidence for Nearby Circumstellar Material in the Type Ia Supernova 2025rbs

Aravind P. Ravi, Griffin Hosseinzadeh, Stefano Valenti, Saurabh W. Jha, Jennifer Andrews, David J. Sand, Benjamin J. Fulton, William D. Vacca et al.

We present a high-resolution spectral time series of the Type Ia supernova (SN) 2025rbs discovered in the nearby galaxy NGC 7331. The Automated Planet Finder (APF) at Lick Observatory and the MAROON-X/IGRINS-2 at Gemini North were used to obtain echelle spectra between -5 and 15 days with respect to the epoch of maximum light. Several unsaturated NaID absorption components along the line of sight are identified, but there is no evidence of time variance in any of them. We measure the equivalent…

詳細を見る →
astro-ph.SRastro-ph.HE

Radio Properties of RS Canum Venaticorum Variables in VLASS and RACS

Suhasini S. Rao, Gregory R. Sivakoff, Craig O. Heinke, Swetha Arumugam, Dougal Dobie, Laura Driessen, David L. Kaplan, Emil Lenc et al.

We performed a systematic search for radio emission from RS Canum Venaticorum (RS CVn) binaries, selected from the International Variable Star Index (VSX) catalog, in the Very Large Array Sky Survey (VLASS; three epochs) and Rapid ASKAP Continuum Survey (RACS; two epochs) data. We detected 108 candidate radio-emitting RS CVn in at least one epoch. Several of these systems rank among the most radio-luminous RS CVn binaries reported to date. The radio and X-ray luminosities, obtained from cross-ma…

詳細を見る →
astro-ph.HE

Observational Constraints on Horizonless Compact Objects from Thermal Emission in AGNs

Ekin Oran, Avery Broderick, Kiana Salehi

The Swift Burst Alert Telescope Active Galactic Nuclei Spectroscopic Survey (BASS DR2) provides one of the largest and most complete samples of bright, local (z < 0.1) active galactic nuclei (AGNs) with high-quality spectroscopic measurements. These sources are typically interpreted within the framework of Kerr black holes; however, a wide range of horizonless compact-object scenarios-including naked singularities, black hole mimickers, and other exotic compact objects-have been proposed as alte…

詳細を見る →