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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.SR

A Detailed Spectroscopic Study of the WN6ha + O5 Colliding-wind Binary WR 25

Eric Gosset, Roberto Gamen, Laurent Mahy, Nidia Morrell, Hugues Sana, Rodolfo Barbá

Massive stars have a major impact on their environment in their host galaxy. Observational determinations of their physical parameters are required to better constrain evolutionary models. In this context, the binary system WR 25 whose dominant spectral type is that of a nitrogen sequence Wolf-Rayet star, is of particular interest. It exhibits the highest known hydrogen content among the Milky Way Wolf-Rayet stars, as well as additional absorption lines. It is most probably an object still on th…

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astro-ph.IMphysics.optics

Sensitivity of Laguerre-Gaussian Modes to Misalignment and Mode Mismatch in Gravitational-Wave Detectors

Liu Tao, Matteo Barsuglia

Higher-order Laguerre-Gaussian (LG) modes have broader and more uniform transverse intensity distributions than the fundamental Gaussian mode, making them attractive for precision optical applications. In gravitational-wave detectors, their enhanced spatial averaging of thermally driven test-mass fluctuations can reduce thermal noise. Their implementation, however, requires efficient coupling of the injected beam to the target cavity eigenmode. Residual misalignment and mode mismatch couple powe…

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gr-qcastro-ph.HEhep-th

Entropy dynamics in gravitational collapse: From Minkowski breaking to de Sitter thermodynamics

Francisco S. N. Lobo, Manuel E. Rodrigues

The origin of black hole entropy remains one of the deepest mysteries in modern physics. Two recent developments offer complementary perspectives on this puzzle: the entropy release from regular Schwarzschild black holes with a de Sitter core (the OCK construction), and the local thermodynamics of the de Sitter vacuum (Volovik). In the OCK framework, the inner horizon carries positive Bekenstein-Hawking entropy $S_{\rm inner}=πh_c^2$ that is gradually released as the core shrinks, until a classi…

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gr-qcastro-ph.SRphysics.class-ph

The Magnusian generator for dissipative systems and application to leading 2.5PN radiation-reaction dynamics

Francisco M. Blanco

The Magnusian is a phase-space function that generates finite-time evolution through nested Poisson brackets. It is related to several familiar generators of classical dynamics, including the radial action, the eikonal phase and related quantities. In this work, we extend the Magnusian framework to systems with dissipation and nonlocal-in-time interactions using the in-in formalism, also known as the Schwinger-Keldysh or Galley formalism. This framework is particularly natural for binary dynamic…

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astro-ph.GA

Radio Jet Properties of the Flaring Gamma-Ray Blazar PKS 0346-27

Máté Krezinger, Sándor Frey, Krisztina É. Gabányi

The blazar PKS 0346-27 at redshift z=0.991 is among the most distant extragalactic sources detected in very high energy gamma-rays. It underwent a major flare reaching TeV energies in November 2021. Recent modelling of its spectral energy distribution favoured a single-zone proton--synchrotron-dominated hadronic model with bulk Lorentz factor Gamma=10 over a single-zone leptonic jet model with much higher Gamma. Here we analyse archival radio data to give independent estimates of the jet bulk Lo…

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astro-ph.SRastro-ph.HE

Testing the theory of colliding winds: the periastron passage of 9 Sagittarii. II. Radio monitoring

R. Blomme, G. Rauw, D. Volpi, Y. Nazé, R. Prinja

Colliding winds in massive-star binaries generate non-thermal radio emission and an increased X-ray emission. We study the radio emission of the non-thermal emitter 9 Sgr, which is a long-period and highly eccentric binary. We conducted a monitoring campaign of 9 Sgr around its 2013 - 2014 periastron passage, obtaining radio, X-ray and optical spectroscopy data. In this paper, we analyse the radio data. The radio data at 3.6, 6 and 20 cm show a maximum near periastron. Other non-thermal radio em…

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astro-ph.COastro-ph.GA

Local luminosity functions of galaxies at (sub)millimeter wavelengths from Planck surveys

Matteo Bonato, Gianfranco De Zotti

The Planck all-sky surveys at (sub)millimeter wavelengths enable us to accurately determine the corresponding local luminosity functions up to the highest luminosities. The detected galaxies are strictly local, so evolutionary effects, which are known to be particularly strong at these wavelengths, are not a problem. However, previous studies have so far relied only on the Planck Early Release Compact Source Catalog (ERCSC) for this purpose. Another important improvement over earlier estimates i…

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astro-ph.SRastro-ph.EP

Locate a stellar flare from the M dwarf LAMOST J1332+5057

Guang-Wei Li, Gui-Ping Zhou, Bing Du, Yan-Xin Guo, Wei-Hua Wang

Young M-type stars exhibit frequent flares, which would seriously impact their habitable planets. Since stellar surfaces cannot be resolved, flare locations remain unknown. Here, by using the Mg I b emission line in LAMOST spectra, the location of a stellar flare from a young M dwarf is pinpointed at $ (-123.0^{+8.0}_{-5.8}, 80.5^{+2.9}_{-3.2})$ in degree in the polar region. Our method can be used to accurately locate stellar flares. This would enable us to assess the impact of stellar flares o…

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astro-ph.GA

Effects of temperature-dependent optical properties on the determination of interstellar dust masses

Lapo Fanciullo, Jonathan P. Marshall, Francisca Kemper, Peter Scicluna, Sundar Srinivasan

Accurate measurements of interstellar dust mass are key to answering several astrophysical questions. A common method of obtaining the mass is to fit the far-infrared thermal emission of the dust with a modified blackbody model; however, this method is subject to several systematics. In particular, how temperature-dependent dust optical properties affect fit results has received little attention. We provide the first quantification of this effect based on experimental measurements of optical pro…

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physics.plasm-phastro-ph.HEphysics.acc-ph

Quasistatic modeling of ultrarelativistic beam-plasma instabilities

P. San Miguel Claveria, L. Gremillet, X. Davoine, Q. Labro, A. Matheron, M. Tamburini, F. Fiuza, S. Corde et al.

Relativistic particle beams propagating through dense ambient plasmas are susceptible to streaming instabilities that can govern the system dynamics in various astrophysical and laboratory settings. For an unmagnetized, collisionless plasma pervaded by a dilute, cold relativistic beam, the dominant instabilities are the quasielectrostatic, oblique two-stream (OTSI) and the essentially magnetic, current filamentation instability (CFI). While their linear and nonlinear properties have been researc…

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astro-ph.IM

First high-contrast results on THD2 testbed after infrastructure upgrade

Iva Laginja, Pierre Baudoz, Rémi Soummer, Emiel H. Por, Axel Potier, Johan Mazoyer, Raphaël Galicher, David Doelman et al.

We present the first scientific results delivered by the upgraded THD2 high-contrast imaging testbed. We report two advances enabled by its improved stability and broadband performance. First, for the Roman Space Telescope, we demonstrate that Gaussian-shaped diversity probes outperform the baseline sinc probes by reducing non-linearities, supporting higher probe amplitudes, and improving electric field estimation efficiency. These results have led to their prioritization as an enhanced early ob…

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physics.plasm-phastro-ph.HE

Modeling ultrarelativistic streaming plasma instabilities under the quasistatic approximation

P. San Miguel Claveria, Q. Labro, X. Davoine, A. Matheron, M. Tamburini, S. Corde, L. Gremillet, F. Fiuza et al.

Plasma streaming instabilities excited by relativistic charged particle beams play a pivotal role in astrophysical and laboratory environments. Their numerical study, however, is challenged by the disparity in spatiotemporal scales between the background plasma and beam particles, which can differ by several orders of magnitude for tenuous, ultrarelativistic beams. Here, we exploit the quasistatic approximation (QSA) to develop a new theoretical framework capable of capturing the full unstable s…

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astro-ph.HEastro-ph.GAgr-qc

Probing an Intermediate-Mass Black Hole Companion of Sagittarius A* with Pulsar Timing

Zexin Hu, Lijing Shao

An intermediate-mass black hole (IMBH) hidden in our Galactic Center (GC) may explain the puzzling observations of the stellar distribution around Sagittarius A* (Sgr A*), the supermassive black hole (SMBH) in the GC. Future observations with the next-generation radio telescopes, such as the SKA, are promising to discover pulsars orbiting around Sgr A*, and thus provide the possibility of constraining the hidden IMBH with pulsar timing. We study the detectability of a third-body, the IMBH, in th…

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astro-ph.SRastro-ph.IM

The Payne Zero Project I: Stellar Spectra from Physical Models in Seconds

Yuan-Sen Ting, Elliot M. Kim

Modern stellar surveys measure millions of spectra, yet one self-consistent atmosphere and spectrum can require tens of minutes. This cost has motivated grids, spectral emulators, and data-driven models. We present Payne Zero, which reorganizes one-dimensional LTE Kurucz calculations for GPU-native synthesis and multicore atmosphere iteration, and validate it against the original Fortran programs. A 300--1000 nm solar spectrum sampled at $R_{\rm grid}=300{,}000$ takes about 14 s on an NVIDIA H10…

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cond-mat.mtrl-sciphysics.space-ph

Recrystallisation phenomena in an ultrafine-grained Al-Mg-Si alloy revealed by correlative in situ EBSD and TEM heating

Moritz Theissing, Sandra Gonzaga, Patrick Willenshofer, Thomas M. Kremmer, Stefan Pogatscher, Stefan Mitsche, Frank F. Sene, Matheus A. Tunes et al.

Ultrafine-grained (UFG) aluminium alloys are promising lightweight structural materials for space applications, where a high grain-boundary density can act as sinks for irradiation-induced defects. Their deployment, however, is contingent on thermal stability: aluminium components in low-Earth orbit can reach $\sim$200 $^\circ$C under solar irradiation, close to where severely deformed aluminium alloys recrystallise. Accurate, bulk-representative determination of recrystallisation onset is there…

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astro-ph.GA

Evidence for Azimuthally Anisotropic MgII Absorption around DESI Luminous Red Galaxies

Xuanyi Wu, Cheng Li

We use DESI DR1 luminous red galaxies (LRGs) and background quasar spectra to measure the mean MgII equivalent-width field around massive quiescent galaxies as a function of projected radius and azimuth relative to the projected major axis. Our forced-measurement approach assigns a MgII doublet-window EW to every LRG-quasar pair, including spectra without individually detected absorbers, and subtracts a redshift-matched random-control signal measured from the same normalized quasar spectra. The…

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astro-ph.IMcs.AIcs.RO

HELIOS: An LLM-Driven Autonomous Indirect Trajectory Optimization Agent

An-yi Huang

Low-thrust trajectory optimization is a core technology in deep-space mission design. Indirect methods based on Pontryagin's Minimum Principle (PMP) offer rigorous optimality guarantees, yet their practical application faces three bottlenecks: (1) transversality conditions must be derived case by case for each constraint type; (2) different dynamics models require repeated code rewrites; and (3) shooting equations are highly sensitive to initial guesses. This paper presents HELIOS (Heuristic Eng…

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astro-ph.HE

Shock breakout from mildly relativistic ejecta in a dense wind: the case of EP260321a/SN~2026gzf

Akihiro Suzuki, Keiichi Maeda, Toshikazu Shigeyama

We present shock breakout (SBO) modeling of the recently discovered X-ray transient EP260321a detected by the \textit{Einstein Probe} mission. Our semi-analytic model, based on our previous work, follows the interaction between a supernova ejecta with a mildly relativistic outer envelope and a dense, wind-like circumstellar medium (CSM) by using a thin-shell approximation that incorporates relativistic effects. We find that the observed properties of the X-ray emission are well explained by the…

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astro-ph.EPastro-ph.SR

JWST/NIRCam Imaging of Young Stellar Objects. IV. Detailed Imaging of the Protoplanetary Disk around TW Hya

Yu-Chia Lin, Jarron Leisenring, Schuyler G. Wolff, Justin Hom, Kellen Lawson, Ewan S. Douglas, George Rieke, Gabriele Cugno et al.

As the nearest protoplanetary disk to Earth ($d = 60.14$ pc), TW Hya is one of the most studied protoplanetary disks and a critical benchmark for testing planet formation theories. We present high-contrast coronagraphic imaging of the TW Hya disk from JWST/NIRCam across four filters (F187N, F200W, F356W, and F444W). We detect the disk's scattered-light emission in F200W, F356W, and F444W. An elliptical fit to the disk image yields an average inclination of $i = 8.74^{+1.03}_{-0.94}$ degrees and…

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astro-ph.GA

The effect of triaxial galaxy shapes on the dynamics of triple supermassive black holes in a cosmological context

Navonil Saha, Margarita Sobolenko, Peter Berczik, Andreas Just, Fazeel Mahmood Khan

The hierarchical nature of galaxy formation in the Lambda cold dark matter ($Λ$CDM) cosmological framework model often leads to the presence of multiple supermassive black holes (SMBHs) in the galactic nuclei. The timescale over which galaxies merge plays a crucial role in shaping the dynamical evolution and the merger dynamics of their central SMBHs. While binary SMBH evolution has been extensively studied, the long-term dynamics of triple SMBH systems, especially in realistic, nonspherical gal…

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astro-ph.EP

Predicted Ejecta Dynamics and Observability of the 2026 Falcon 9 Upper Stage Lunar Impact

William Jo, David B. Goldstein, Philip L. Varghese, Laurence M. Trafton, Jordan K. Steckloff, Arnaud Mahieux

On Aug. 5 at 06:34 UTC, a Falcon 9 upper stage (~3,900 kg) will strike the lunar surface at 2.43 km/s, yielding a potentially visible debris plume. We present a study of the expected impact dynamics and resulting possibly observable debris field. The debris plume should reach roughly 15 to 20 km in altitude for the ejecta curtain and 75 to 100 km for the central ejecta spike, extend 183 km laterally from the impact point near the sunlit limb, and yield a peak dust column density above 10 km alti…

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astro-ph.SRastro-ph.GA

A Century of Novae in the Large Magellanic Cloud

Allen W. Shafter

A comprehensive study of novae in the Large Magellanic Cloud (LMC) is presented. A total of 66 nova eruptions have been reported in the LMC over the past century (1926-2025). Of these, a total of 48 eruptions from 39 unique progenitor systems (9 eruptions are recurrences of 4 known recurrent novae) have sufficient photometric data to permit the maximum magnitudes and rates of decline to be reliably estimated. These data confirm earlier studies showing that LMC novae are, on average, slightly mor…

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astro-ph.GAastro-ph.SR

Neighbors, Not Kin: Kinematic evidence for tidal tails from NGC 7492 along the Sagittarius stream

Camila Navarrete, Álvaro Rojas-Arriagada, Andrés E. Piatti, Julio A. Carballo-Bello, Luca Sbordone, Richa Kundu, Vasily Belokurov, Sergey E. Koposov et al.

The formation, extension, and morphology of extra-tidal stars around globular clusters depend on the internal kinematics of the host cluster and the Galactic potential. Tracing the kinematics of faint tidal tails sheds light on their formation and contribution to the Milky Way halo. NGC 7492 is an outer halo globular cluster with conflicting evidence regarding the presence of tidal tails. If present, the tails are expected to be faint and overlap on the sky with the Sagittarius stream, located a…

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astro-ph.IM

Progress of the design of the 12-m optical, Wide-field Spectroscopic Telescope (WST)

P. Dierickx, G. Gausachs, C. Cudennec, D. Lee, R. Bacon, T. Travouillon, O. Bellido-Tirado, B. Sassolas et al.

The Wide-Field Spectroscopic Telescope (WST) is a 12-m class, Alt-Az optical telescope providing two simultaneous foci, 2 degrees and 3 by 3 arc minutes respectively, for Multi-Object Spectroscopy (MOS) and Integral Field Spectroscopy (IFS) at visible wavelengths. Within the framework of the Horizon Programme, the project has been approved for phase A funding by the EC in 2024 and is currently undergoing intensive development. The optical design relies on a corrected Cassegrain solution feeding…

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astro-ph.EP

A uniform transit survey of 461 ExoFOP M-dwarf TOI hosts: Follow-up prioritization and new transit candidates

Yohann Tschudi

Context. M dwarfs are favorable hosts for small transiting planets. A transit-detection and statistical-validation pipeline was previously developed and validated at the photometric noise frontier, on M3-M6 dwarfs observed in few sectors. Aims. That pipeline is applied uniformly to the full active ExoFOP M-dwarf TOI population, 461 hosts (M0-M6) each hosting a confirmed planet (CP) or planet candidate (PC), to test its recovery and classification of the cataloged signals and to prioritize the ca…

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astro-ph.GA

Spatial Correlations of PAH, UV, H$α$ Emission and IMF - PAH Variations in the Star-Forming Complexes of NGC 628

S Amrutha, Dimitra Rigopoulou, Mousumi Das, Jyoti Yadav

We examine the spatial correlation of emission from polycyclic aromatic hydrocarbons (PAH) (3.3 $μ$m, 7.7 $μ$m, and 11.3 $μ$m) with the far-ultraviolet (FUV), near-ultraviolet (NUV), and H$α$ emission from star-forming complexes (SFCs) in different regions of NGC 628. We use the James Webb Space Telescope to detect PAH emission, along with the Ultraviolet Imaging Telescope and Multi Unit Spectroscopic Explorer observations to sample the UV and H$α$ emission, respectively. We investigate the corr…

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astro-ph.SRphysics.plasm-phphysics.space-ph

Spectral properties of mesoscale fluctuations in interplanetary coronal mass ejections

Anna-Sofia Jylhä, Simon Good, Emilia Kilpua

Magnetic fields in interplanetary coronal mass ejections (ICMEs) often display a flux rope structure at large scales and a turbulent cascade of fluctuations at smaller scales. However, the nature of fluctuations at transition scales between the flux rope and turbulence - i.e., at mesoscales - has not been previously examined in detail. Mesoscale fluctuations of the magnetic field in 142 ICME intervals with clear flux rope signatures at 1 au have been examined using wavelet power spectra, with "m…

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astro-ph.EPastro-ph.SR

Angular Momentum of Planet-Forming Disks: Implications for Infall Driven Misalignments

Aashish Gupta, Cristiano Longarini, L. Ilsedore Cleeves, Giovanni P. Rosotti, Edwin A. Bergin, Cathie J. Clarke, Michael Küffmeier, Zhi-Yun Li et al.

Context. A significant fraction (>30%) of planet-forming disks and planetary are misaligned with respect to the rotational axis of their host stars, yet the dominant mechanism responsible for these misalignments remains unclear. Aims. We aim to observationally constrain the angular momentum of Class II protoplanetary disks and assess whether late-stage infall of material can bring sufficient angular momentum to tilt them. Methods. We first computed the angular momenta of 15 disks with surface de…

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astro-ph.HE

Dust Without Na I D Trace: The Case of Highly Attenuated Type Ib SN 2024vjc

Javier Silva-Farfán, Keiichi Maeda, Andrea Pastorello, Hanindyo Kuncarayakti, Takashi Nagao, Giorgio Valerin, Andrea Reguitti, Dino Pierluigi Fugazza et al.

Understanding dust attenuation toward extragalactic transients is critical for recovering their intrinsic properties and probing the local environments of distant galaxies. A popular diagnostic is the Na I D absorption equivalent width widely applied to extragalactic transients. In this paper, we present early-time optical and near-infrared observations of the Type Ib supernova (SN) SN 2024vjc, followed for $\sim$130 days post-explosion. SN~2024vjc exhibits only weak Na~I~D absorption, indicatin…

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gr-qcastro-ph.HEhep-th

Upper bounds on the force function in spatially regular self-gravitating matter configurations

Shahar Hod

We use the non-linearly coupled Einstein-matter field equations to prove four theorems that bound from above the dimensionless force function ${\cal F}=4πr^2\cdot p(r)$ in spatially regular curved spacetimes of spherically symmetric self-gravitating matter configurations [here $p(r)$ is the radially-dependent pressure inside the spatially regular matter configurations]. In particular, for generic (not necessarily isotropic) matter configurations it is proved that: (i) ${\cal F}\leq 2$ for matter…

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