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宇宙工学・惑星科学・宇宙物理の最新プレプリント。

astro-ph.EP

A Possible Complication of Using the 4.14 μm band to Assess D/H Ratios on Icy Bodies

Mark J. Loeffler, Rebecca A. Carmack, Stephen C. Tegler

Determining isotopic ratios on the surfaces of extraterrestrial objects can provide insight into their formation conditions and evolution. Recently, remote-sensing detections of the 4.14 μm HDO absorption band have enabled astronomers to estimate the D/H ratio on several icy objects in the outer solar system. Here, we quantify how ice phase and radiation processing affect the 4.14 μm absorption band. While the band is visible in H2O-ice samples with a crystalline component, we cannot detect it i…

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gr-qcastro-ph.HE

Constraining the Quadratic-mode Amplitude Coupling in GW250114

Yuxin Yang, Changfu Shi, Yi-Ming Hu

Detecting quadratic quasi-normal modes in black hole ringdowns would provide evidence for nonlinear gravitational dynamics, while measuring their properties would enable tests of the corresponding predictions of general relativity. Specifically, second-order black hole perturbation theory predicts that their amplitudes scale with the product of the amplitudes of their parent linear modes, with a coupling coefficient that depends on the spin of the remnant black hole. This mode-specific coupling…

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astro-ph.HEastro-ph.COastro-ph.IM

DETECT: Real-Time Identification of Transients with DESI Spectroscopic Redshift

Yu-Hsing Lee, Ting-Wan Chen, Ze-Ning Wang, Sheng Yang, Limeng Deng, Chuan-Jui Li, K. C. Chambers, Thomas de Boer et al.

Wide-field surveys now report thousands of transients per month, while spectra are obtained for only a few per cent of them. We present DETECT (DESI--Transient Event Cross-matching Tool), a pipeline that turns each Transient Name Server (TNS) alert into a distance-informed candidate within an hour by placing it in the context of the Dark Energy Spectroscopic Instrument (DESI) archive. DETECT cross-matches every new report against the 22 million spectra of DESI EDR and DR1 through a HEALPix index…

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astro-ph.EPastro-ph.SR

A Collisional Origin for Ice-rich Iapetus and Titan's Anomalous Eccentricity

Ignacio Mosqueira

We test whether collisions involving Titan can eject enough water-rich material onto sufficiently distant Saturn-bound orbits to form Iapetus, while also accounting for Titan's orbital eccentricity. Three-dimensional impact calculations and post-impact trajectories examine initially Saturn-unbound and bound impactors. In the oblique unbound case with a differentiated impactor roughly a tenth the mass of Titan at a speed of 10 km s\(^{-1}\), outgoing predominantly icy material from a selected pop…

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astro-ph.HEastro-ph.GA

Recurrent double-peaked $γ$-ray sub-flares in PKS 1424-418

Na Wang, Tong Liu, Jingran Xu

We report a hint of recurrent double-peaked $γ$-ray sub-flares in PKS~1424--418 during two similar major active epochs, MJD 56117--56498 and MJD 59669--59978. The candidate double-peaked sub-flares show a characteristic intra-subflare peak separation of $\sim 11.8$ d and a neighbouring-subflare spacing of $\sim 67$ d. Red-noise Monte Carlo tests indicate that the candidate recurrent double-peaked morphology is not easily reproduced by stochastic variability alone, with false-alarm probabilities…

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astro-ph.HE

Radiative properties and optical appearance of a thin accretion disk around a charged-PFDM black hole

Taiyang Zhang, Zongyuan Qin, Qian Feng, Zheng-Wen Long

Accretion onto magnetically charged black holes in a perfect fluid dark matter (PFDM) background opens a new window for testing strong-field gravity. This paper investigates the radiative properties and optical appearance of a thin accretion disk surrounding a charged-PFDM black hole. We numerically compute the radiative energy flux, temperature distribution, and radiative efficiency, and employ a ray-tracing method to construct the direct images, secondary images, redshift distribution, and obs…

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astro-ph.SR

Study of Chromospheric Global-Scale Flows using Local Correlation Tracking Across the past 10 Solar Cycles

Qin Li, Yan Xu, Keiji Hayashi, Chunlei Liang, Haimin Wang

Global-scale solar surface flows, including differential rotation and meridional circulation, provide key observational constraints on the solar dynamo. We investigate these flows using local correlation tracking (LCT) of chromospheric intensity structures in digitized \ion{Ca}{2}~K observations from the Kodaikanal Solar Observatory covering Solar Cycles (SC) 14 to 23 (1907 -- 2007). The most valuable data coverage are from cycles 14 to 19 for two reasons: (1) it provided record for early cycles…

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astro-ph.SR

Central stars of newly discovered infrared nebulae: eruptive Be stars PY Gem and HD253659

Olga Maryeva, Julieta Sánchez Arias, Sergey Karpov, Michaela Kraus, Michalis Kourniotis, Sabina Mammadova

The presence of a nebula around massive hot stars often works as an indicator that the object is either in an advanced evolutionary stage or a rare product of close binary interaction. Here, we focus on two Be stars - PY Gem and HD253659 - whose nebulae were detected with the Wide-field Infrared Survey Explorer. We estimated their basic physical parameters from modelling the spectral energy distribution and examined their variability. We combined archival photometric data from several ground-bas…

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cs.LGastro-ph.IMastro-ph.SR

Image Fidelity is Not Field Fidelity: Joint Thermodynamic Reconstruction and Error Localization in Neural Tomography

Alan Hsu, Jenna Samra, Alin Razvan Paraschiv, Liam Connor

Neural fields for scientific tomography are optimized from 2D images, but the actual quantity of interest is often a latent 3D physical field. Because the forward map is many-to-one, low 2D image error need not certify a correct 3D field. Moreover, the latent field is not directly supervised during training, and its error cannot be evaluated against truth at deployment. We develop CoroNeRF to jointly optimize 3D electron density and temperature fields directly from multiview, multiline intensiti…

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astro-ph.EP

On the Long-Term Orbital Behaviour of Hilda Asteroids - I. Global Stability Patterns and Catalogue

Cristian F. Chavez, Jonathan Horner, Patryk Sofia Lykawka, Timothy R. Holt, Brad Carter

The Hildas are objects trapped in 3:2 mean-motion resonance (MMR) with Jupiter, and are a fascinating window into the Solar system's formation and evolution. We present the results of detailed dynamical integrations of 2,699 numbered asteroids in the Hilda region, following 243 clones of each Hilda for 1 Gyr under the influence of the giant planets and the Sun; 54.7% of our sample exhibit extreme dynamical stability, with all clones of 1,475 Hildas remaining trapped in the 3:2 MMR for the full 1…

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astro-ph.HEastro-ph.GA

Dissecting the variability of Sagittarius A* in the orbiting hotspot framework

Maciek Wielgus, Aristomenis Yfantis

Sagittarius A* (Sgr A*) exhibits intermittent flaring behavior, characterized by strong enhancements in high-energy emission (infrared and X-ray). These events have been interpreted as related to the coherent orbital motion of localized regions of energized plasma - hotspots. While this framework has been quite fruitful in constraining properties of Sgr A*, it is subject to important challenges and limitations. In this brief review we discuss the recent observational and theoretical developments…

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astro-ph.IMastro-ph.CO

PSFSim: PhySics First Simulations for the Point Spread Function of the Roman Space Telescope

Nihar Dalal, Chris Hirata, Charuhas Shiveshwarkar, Anthony Harbo Torres, Chun-Hao To, Elise Moore, Katherine Laliotis, David Kuhtenia et al.

We present a new tool for generating simulated point spread functions (PSFs) in the Wide Field Instrument (WFI) of the Nancy Grace Roman Space Telescope. The simulation tool is physics forward, and performs a raytrace of the optical system of the instrument to compute the PSF, while also accounting for various detector effects. The tool also has the capability to add perturbations to the optical system and detectors. We explore several applications of the tool that may arise during the commissio…

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hep-phastro-ph.HEhep-ex

Heavy Inert Doublet Reconciles LZ and IceCube

Hitoshi Murayama, Bea Noether

We show that the inert doublet dark matter can reconcile the purported LZ direct detection signal and IceCube constraints. The preferred dark matter mass is 11.3--20.3~TeV, an order of magnitude heavier than the standard higgsino target. The smaller number density at a high mass can reproduce the LZ event given the exponential sensitivity to the velocity, while suppressing the capture rate in the Sun because of the higher infall velocity. On the other hand, the high mass requires a large couplin…

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astro-ph.GA

Cluster Membership Probabilities: A Review of Methods and Gaia Applications

Tahereh Ramezani, Johana Balciráková, Prapti Mondal, Katerina Neumannova, Ernst Paunzen, Gabriel Szász

Reliable stellar-cluster membership is essential for deriving cluster ages, distances, reddenings, metallicities, mass functions, dynamical parameters, and Galactic-structure tracers. The Gaia era has produced a proliferation of membership and cluster-detection methods, but the resulting catalogues are not interchangeable. We review the historical development of membership assignment, compare the statistical assumptions of major methods, and explicitly examine the practical consequences of metho…

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astro-ph.SRastro-ph.EPastro-ph.GA

Metal-poor Brown Dwarf Kinematics from JWST NIRSpec Spectroscopy

Chih-Chun Hsu, Christopher A. Theissen, Adam J. Burgasser, Adam C. Schneider, Christian Aganze, Aaron M. Meisner, Jonathan Gagné, Nicolas Lodieu et al.

Galactic archaeology relies on stellar kinematics and chemical abundances to identify various stellar populations and associations. With JWST, Galactic archaeology of ancient metal-poor brown dwarfs is now possible through high-sensitivity, medium-resolution spectroscopy. We present the first metal-poor brown dwarf radial velocity (RV) survey using JWST/NIRSpec G395H spectra ($λ/Δλ\sim$ 3,000) for a sample of 23 LTY dwarfs across a wide range of temperatures and metallicities. We introduce a for…

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astro-ph.SRastro-ph.EPastro-ph.GA

Metal-poor Brown Dwarf Kinematics from JWST NIRSpec Spectroscopy

Chih-Chun Hsu, Christopher A. Theissen, Adam J. Burgasser, Adam C. Schneider, Christian Aganze, Aaron M. Meisner, Jonathan Gagné, Nicolas Lodieu et al.

Galactic archaeology relies on stellar kinematics and chemical abundances to identify various stellar populations and associations. With JWST, Galactic archaeology of ancient metal-poor brown dwarfs is now possible through high-sensitivity, medium-resolution spectroscopy. We present the first metal-poor brown dwarf radial velocity (RV) survey using JWST/NIRSpec G395H spectra ($λ/Δλ\sim$ 3,000) for a sample of 23 LTY dwarfs across a wide range of temperatures and metallicities. We introduce a for…

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astro-ph.EPastro-ph.GAastro-ph.SR

Triggering star formation by free-floating planets

Yu. N. Eroshenko

Recently, a population of free-floating planets has been discovered in the Galaxy. This paper examines the influence of the planets trapped within a protostellar hydrogen clouds on the processes of gravitational instability in the gas. A sufficiently massive planet can become an alternative dynamic center for the contracting cloud. This occurs due to rapid mass growth from accretion onto the planet within the cloud. Owing to residual velocity and density gradients in the cloud, the planet that t…

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astro-ph.SRastro-ph.HE

A comprehensive multi-wavelength study of two X-ray emitting Be stars

Hema Anilkumar, Blesson Mathew, Savithri H. Ezhikode, Sreeja S. Kartha, Suman Bhattacharyya, Sneha Nedhath, Ajith N

We present a multi-wavelength study of two X-ray-emitting Be stars, CXOU J052218.4+332820 (Star 1) and CXOU J052304.2+332846 (Star 2), identified from the LAMOST DR5 Hot emission-line stars catalog. Our spectroscopic and photometric analyses indicate that Star 1 is a main-sequence B5e star, whereas Star 2 is a pre-main-sequence B7e star. The LAMOST spectrum of Star 1 exhibits shell-type Feii, Paschen, and Oi emission from circumstellar regions extending to ~ 3 - 5Rstar. TESS period analysis reve…

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astro-ph.HEastro-ph.SR

Tomography analysis of the intermediate-luminosity Type Iax SN 2024pxl

Barnabás Barna, Mridweeka Singh, Lindsey A. Kwok, Saurabh W. Jha, R. Dastidar, Conor Larison, Alexei V. Filippenko, J. P. Anderson et al.

We present an abundance tomography analysis of SN 2024pxl, an intermediate luminosity Type Iax supernova ($M_{r}=-16.82 \pm 0.19$ mag), with the most-detailed follow-up in the Type Iax subclass to-date. As one of the few intermediate luminosity Type Iax objects, SN 2024pxl may link the two extremes of the peculiar thermonuclear supernova subclass. To test this hypothesis, we analyze its spectral evolution through the first 100 days after the explosion and aim to probe the structure of its ejecta…

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astro-ph.HEhep-phnucl-th

Stability of hybrid stars via catastrophe theory

Eduardo S. Fraga, Sergio E. Jorás

We discuss the possible topologies of the mass-radius relation for hybrid stars in light of catastrophe theory. We show that different branches of compact stars emerge or disappear depending on the bifurcation structure of the underlying catastrophe potential function, the mathematical analog of an effective potential. For that we assume a single first-order phase transition between nuclear and quark matter. After a warm up with incompressible fluids, we present a qualitative discussion explaini…

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hep-phastro-ph.HEphysics.plasm-ph

Plasma instability splits axion-photon conversion lines

Elizabeth A. Tolman

The axion coupling to electromagnetism may leave signatures of uncertain nature in astrophysical spectra; one is thought to be a single line centered at the axion frequency $ω= \sqrt{\left(m_a c^2/\hbar\right)^2 + c^2 k_a^2}$, with $m_a c^2/\hbar$ the axion Compton frequency and $\hbar k_a$ its momentum. If a parametric plasma instability is excited, this signature is transformed into a set of lines, which may be proportionally spaced and linearly polarized. A Crab pulsar signal at a frequency n…

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astro-ph.HE

Composition-dependent acceleration of UHE Cosmic Rays in AGN electric fields

E. Koutsoumpou, I. Contopoulos, A. Nathanail, A. Loules, D. Kazanas

The origin of ultra-high-energy cosmic rays (UHECRs) remains elusive, as proposed acceleration mechanisms are rarely connected directly to composition-sensitive air-shower observables. We establish such a connection for voltage-drop acceleration in near-horizon current sheets of magnetically arrested disks around supermassive black holes. Fragmentation is represented by a log-normal distribution of effective potential-sampling factors $η$, with $μ_η=\langle\lnη\rangle$, $σ_η=[\mathrm{Var}(\lnη)]…

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astro-ph.SR

The physics of deep-interior convective shell boundaries in a massive pre-supernova star: Internal gravity wave mixing at the $N^2$ peak

Praneet Pathak, Falk Herwig, Simon Blouin, Paul R. Woodward, Joshua Issa

The physics of convective boundary mixing involves concepts such as penetration and overshooting and has been mostly characterized for envelope and core convection. For the burning shells deep inside massive stars in their final stages, the convective boundary remains poorly understood. 1D stellar-evolution codes typically place a steep entropy gradient and the corresponding narrow \brunt{} ($N^2$) peak at a lower convective shell boundary. Based on high-resolution 3D hydrodynamic simulations of…

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astro-ph.SRastro-ph.HE

3D Radiation Hydrodynamics of Blue Supergiant Envelopes

Linhao Ma, Lars Bildsten, Yan-Fei Jiang

We present the first 3D radiation hydrodynamical simulation of the outer envelope of a blue supergiant. These near Eddington limited massive stars in the Hertzsprung gap exhibit substantial photometric variability and have spectroscopic line widths indicating unexplained macroturbulent velocity fields. Our Athena++ simulations find that the convection associated with the opacity peak from iron directly extends to the photosphere, as found in previous 3D simulations of massive main sequence stars…

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astro-ph.GA

Mapping the Milky Way in Six Dimensions: A contiguous, homogenised, phase-space catalogue of \textit{Gaia} DR3 tracers up to 250 kpc

Sutirtha Mukherjee, Amogh Srivastav, Subhabrata Majumdar

We present a comprehensive, homogenised catalogue of $32{,}552{,}876$ stellar sources with full 6D phase-space information, spanning Galactocentric distances from the inner galaxy ($\gtrsim 5$\,kpc) to the outer halo ($\sim\!250$\,kpc). By cross-matching \textit{Gaia} DR3 astrometry with spectrophotometric distances and line-of-sight velocities from 14 surveys (including \textsc{desi}, \textsc{sdss-boss}, \textsc{apogee}, \textsc{lamost}, \textsc{galah}, and \textsc{ges}), we achieve median frac…

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astro-ph.HE

Dynamically Stable Magnetic Fields in Relativistic Neutron Stars: A Diverse Landscape of GRMHD Equilibria

Mai Li, Vasileios Paschalidis, Antonios Tsokaros, Maria Mutz, Koji Uryu

Neutron stars endowed with purely poloidal or purely toroidal magnetic fields are known to be unstable, and settle into mixed poloidal-toroidal configurations. The end state of these instabilities is still poorly understood. It is unclear whether this state is unique or whether the dynamically stable configuration has memory of the initial conditions. In this work, we perform long-term, fully general relativistic magnetohydrodynamic simulations of equilibrium configurations of slowly rotating ne…

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astro-ph.SRastro-ph.EP

External photoevaporation in the center of Tr14

Katia Gkimisi, Da Eun Kang, Dominika Itrich, Rossella Anania, Eleonora Fiorellino, Sacha Gavino, Ralf S. Klessen, Victor F. Ksoll et al.

Most stars form in massive stellar clusters, where intense far-ultraviolet (FUV) radiation from OB stars can accelerate the dispersal of protoplanetary disks through external photoevaporation. Quantifying the impact of this process on disk evolution remains challenging, particularly in distant and crowded star-forming regions. We investigate the low-mass stellar population in the highly irradiated center of Trumpler 14 and examine how the local FUV radiation field influences circumstellar disk e…

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astro-ph.SR

Detection of new Galactic Wolf-Rayet stars with SPHEREx

Paul A. Crowther, Erin L. Smith

We assess the potential for the NASA Explorer SPHEREx mission in adding to the Milky Way census of Wolf-Rayet (WR) stars by extracting 0.75--5micron spectrophotometry of 30 candidate WR stars previously identified using Gaia XP spectra. We confirm an additional Galactic 13 WR (8 WN and 5 WC) stars, identify 3 probable [WC]-type central stars of Planetary Nebulae, plus 2 He emission line sources. SPHEREx has the potential to detect additional relatively isolated WR stars on the far size of the Mi…

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astro-ph.HEastro-ph.GA

Probing the Metallicity Dependence of Fast Radio Burst Progenitors with CHIME/FRB Outrigger Dwarf Host Galaxies

Y. Dong, W. Fong, K. Nimmo, N. Loudas, B. C. Andersen, S. Andrew, A. Cai, S. Chatterjee et al.

Using the fast radio bursts (FRBs) localized with the CHIME/FRB Outriggers between February and October 2025, we conduct a systematic search for dwarf host galaxies. We identify and characterize eight host galaxies for one repeating and seven apparently non-repeating FRBs, newly classifying five hosts as dwarfs with stellar masses of $\log(M_\ast/M_\odot) \approx 8.1-9.1$. We measure their gas-phase metallicities and, when combined with hosts from the literature, finding that repeating and non-r…

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astro-ph.GA

The quest for high-redshift radio galaxies II. Discovery of the most powerful known radio galaxy at z=4.946

B. Balmaverde, A. Capetti, M. Chiaberge, F. Massaro, M. Coloma Puga, A. Jimenez-Gallardo

As part of our quest for high-redshift radio galaxies (HzRGs), we present the results obtained from optical spectroscopy leading to the confirmation of one HzRG candidate selected using the Lyman break technique. The optical emission, associated with the radio source TXS 2354+015, exhibits a prominent drop in the r band, which is characteristic of sources at z~5. The optical spectrum shows a bright asymmetric emission line, with a large equivalent width of ~900 Angstrom. Its identification with…

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