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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.HEastro-ph.SR

Fast Radio Bursts from Monster Shocks and Flares of Inspiraling Binary Neutron Stars: A Kinetic Model for Double Pulsar

Jan Benáček, Benoît Cerutti, Martin Pohl, Tim Dietrich, Anna Neuweiler

The coalescence of binary neutron star systems offers unprecedented possibilities for multimessenger observations, including the detection of gravitational waves, gamma-ray bursts, kilonovae, and potentially fast radio bursts. For a detailed investigation of the latter, one requires a kinetic plasma model to describe the interacting magnetospheres of the stars. We present a three-dimensional particle-in-cell kinetic simulation of the combined magnetosphere of a binary neutron star in which the t…

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astro-ph.HEastro-ph.GA

Low-frequency spectra and scattering of pulsars towards the Gum Nebula with the MWA

Ting Yu, Zhifu Gao, Zhongli Zhang, Weicong Jing

Context. The Gum Nebula is a nearby ionised complex with sight-line-dependent pulsar propagation. Aims. We test whether a smooth ionised structure can explain low-frequency spectral turnovers and pulse broadening, or whether smaller-scale material is required. Methods. We analysed Murchison Widefield Array observations of six pulsars at 80--240 MHz, combining sub-band flux densities with literature data. We compared power-law, free--free absorption (FFA), and turnover-constrained broken-power-la…

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astro-ph.SR

MATISSE unveils a dusty disc in the interior of EP Aquarii. First evidence of a misaligned hierarchical triple system with a central AGB star?

J. Alonso-Hernández, C. Paladini, C. Sánchez Contreras, J. Drevon, J. P. Fonfría, L. Planquart, T. Khouri, L. Siess et al.

Aims. We have mapped the dust and molecular gas emission distributions in the vicinity (a few stellar radii) of the asymptotic giant branch (AGB) star EP\,Aquarii, with a previously reported stellar companion at $\sim$50\,au, to search for binary-induced asymmetries. Methods. We present an analysis of new high-angular-resolution ($\gtrsim$4\,mas) images obtained with MATISSE (in the wavelength range $\sim$3--8\,\mum) as well as archival high-angular-resolution ($\gtrsim$20\,mas) ALMA $\rm^{12}$C…

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astro-ph.EP

3D Global Climate Simulations of Synthetic Mars Warming

Tom N. Landefeld, Harald Lesch

Artificial warming via engineered aerosols presents a novel pathway to bypass volatile scarcity on modern Mars. Utilizing the Generic Planetary Climate Model, we evaluate the physical feasibility of aerosol-induced terraforming over a full Martian year (669 Sols). Unlike previous approaches that added aerosols to background dust or assumed continuous nanoparticle injection, we simulate the complete substitution of natural dust with a single-injection profile of radiatively active aluminium nanop…

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astro-ph.EP

3D Global Climate Simulations of Synthetic Mars Warming

Tom N. Landefeld, Harald Lesch

Artificial warming via engineered aerosols presents a novel pathway to bypass volatile scarcity on modern Mars. Utilizing the Generic Planetary Climate Model, we evaluate the physical feasibility of aerosol-induced terraforming over a full Martian year (669 Sols). Unlike previous approaches that added aerosols to background dust or assumed continuous nanoparticle injection, we simulate the complete substitution of natural dust with a single-injection profile of radiatively active aluminium nanop…

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astro-ph.SR

Dynamical and thermal evolution of localized reconnecting current sheets under varying guide-fields in the solar corona

Saksham Pande, Abhishekh Kumar Srivastava, Fabio Bacchini, Sripan Mondal, Akash Bairagi, Balveer Singh, Kartika Sangal, Sudheer K. Mishra et al.

Although magnetic reconnection in coronal current sheets (CSs) is a fundamental energy release mechanism in the solar corona, the role of guide-fields in governing its formation and self-consistent evolution is not fully understood. Through 2.5D resistive magnetohydrodynamic (MHD) simulations, we investigate how guide-fields affect the formation and evolution of a localized reconnecting coronal CS. Strong guide-fields prevent oppositely directed field lines from approaching sufficiently to form…

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astro-ph.IM

Charge Response Simulation of Liquid Argon Compton Cameras for Precise MeV Gamma-Ray Event Reconstruction

Shota Arai, Hirokazu Odaka, Satoshi Takashima, Masashi Tanaka, Ryutaro Tatsumi, Hodaka Kawamura, Kouichi Hagino, Aya Bamba et al.

We studied the detector response for a liquid-argon time-projection chamber (LArTPC) Compton camera targeting MeV gamma-ray astronomy by a Geant4-based Monte Carlo simulation. The simulation, implemented within ComptonSoft, incorporates electron-ion recombination, charge diffusion, and induction on the electrode pixels. We evaluated the angular resolution measure (ARM) and the energy reconstruction error as functions of electronic noise, pixel pitch, and the recombination correction method. An e…

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nucl-thastro-ph.HEhep-ph

Finite-Temperature Equations of State for Neutron-Star Mergers within the Quark Mean-Field Model

Shuochong Han, Xiangdong Sun, Zhenyu Zhu, Ang Li

We extend the quark mean-field (QMF) model to finite temperature and systematically investigate the thermodynamic properties of uniform nuclear matter, using the relativistic mean-field (RMF) model as a reference. For each model, we consider two parameter sets calibrated to the same selected nuclear-matter saturation properties but with different nucleon Dirac effective-mass ratios at saturation. We examine the effective nucleon mass and the composition of $β$-equilibrium matter, together with t…

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astro-ph.GA

Radio ghosts: Radio polarimetry study of newly discovered cluster minihalo candidates or radio tailed galaxies

Sam Taziaux, Christopher J. Riseley, Stefan W. Duchesne, Francesca Loi, Alec J. M. Thomson, Aritra Basu, Timothy J. Galvin, Dominik J. Bomans et al.

Extended diffuse radio emission in the central regions of galaxy clusters is commonly associated with non-thermal processes in the intracluster medium (ICM), but its origin and the mechanisms responsible for sustaining it remain uncertain. We present the discovery and multi-wavelength analysis of two diffuse radio sources, MKTJ0355-4237 and MKTJ0355-4230, to assess their nature and investigate their radio spectral and magnetic field properties through radio polarimetric analysis. We use deep Mee…

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cs.NIastro-ph.IM

Developments in Building Towards the Indian SKA Regional Centre

Rohit Sharma, Yogesh Wadadekar

The SKA Regional Centre Network (SRCNet) is a federated global network designed to archive, distribute, and process SKAO data products. This paper examines the evolving SRCNet architecture-focusing on the transition to version 0.2 (v0.2) requirements, including computation, orchestration, and multi-tiered storage-and details the strategy for establishing its proto-SRC infrastructure. We outline the prototype developments for the major and minor nodes in the context of v0.2. We describe the minor…

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astro-ph.SRastro-ph.IM

Simulating Ionospheric Distortions in Mock SKA-Low Solar Radio Observations

Rohit Sharma, Mitin

The Square Kilometre Array Observatory (SKAO) will provide unprecedented angular resolution for low-frequency solar radio imaging, enabling access to fine-scale coronal structures. However, the improved spatial resolution of SKA-Low also increases the sensitivity of solar images to ionospheric propagation effects. We investigate the impact of ionospheric fluctuations on simulated SKA-Low solar observations at 50, 100, 150, and 200 MHz using the \textsc{Karabo} simulator and turbulent, moving ion…

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astro-ph.GA

Atomic hydrogen in $z=0$ galaxies in the COLIBRE simulations

Kyle A. Oman, Ruby J. Wright, Andrea Gebek, Diego Dado, Katherine E. Harborne, Evgenii Chaikin, Carlos S. Frenk, Filip Huško et al.

We present an overview of the properties of atomic hydrogen (HI) in galaxies at redshift $z=0$ in the COLIBRE cosmological galaxy formation simulations. COLIBRE directly simulates the multi-phase interstellar medium (ISM) and includes new methods to follow radiative cooling to $\approx 10\,\rm{K}$, non-equilibrium chemistry coupled to dust, and dust formation, growth \& destruction. We focus on the $(200\,\rm{cMpc})^3$ volume with resolution elements of $2\times 10^{6}\,\rm{M}_{\odot}$. No HI pr…

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astro-ph.HE

A0538-66: A transient ultraluminous X-ray source with a relativistic outflow, 69ms pulsations, and anomalous optical activity

Lorenzo Ducci, Sandro Mereghetti, Ciro Pinto, Matteo Bachetti, Motoki Nakajima, Rahul Sharma, Stefano Covino, Michela Rigoselli et al.

A0538-66 is a peculiar Be/X-ray binary in the Large Magellanic Cloud, hosting the fastest spinning neutron star of its class (~69ms) and showing the brightest optical bursts of any system of this type. We report four XMM-Newton observations obtained near periastron in 2025, together with MAXI and REM monitoring, and a reanalysis of archival RXTE data. On 30 September 2025 the source reached L_X~1.5E39 erg/s (0.2-10 keV), the highest level since 1980, and in February, May, and August 2026, MAXI d…

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astro-ph.EP

Physical characterization of Earth's quasi-satellite 2025 PN7

Grigori Fedorets, Zuri Gray, Mikael Granvik, Eric MacLennan

A hypothetical origin as lunar ejecta for Earth's quasi-satellites (QS) has gained initial support in recent years, but there is scarce photometric and/or spectroscopic data to support the premise due to the rare observational windows to obtain such data for these small objects. One of the key pieces of evidence supporting the lunar-origin hypothesis, the lunar-like, very red reflectance spectrum of QS (469219) Kamo'oalewa, was recently found to be flawed. We present reflectance spectroscopy of…

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astro-ph.SR

Revisiting the Role of Global Magnetic Variables in Coronal Heating of Solar Active Regions

David H. Brooks, Harry P. Warren, Johnathan R. Stauffer

Reconnection-based models of coronal heating predict that magnetic complexity---non-potential configurations, currents, shear---should enhance coronal emission independently of total magnetic flux. Previous work, however, found no evidence that complexity contributes independently to coronal heating (Fisher et al. 1998). We revisit this question using SDO/HMI vector magnetograms and SDO/AIA EUV imaging. HMI Space-weather Active Region Patches (SHARPs) provide 16 magnetic parameters characterizin…

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astro-ph.EPastro-ph.IMphysics.space-ph

Radiation limits on amino acid preservation and chiral measurement at Oxia Planum

Dimitra Atri

Amino acid enantiomeric excess (EE) is a potential biosignature, but its measurement requires sufficient surviving material as well as preserved chirality. We derive a criterion that separates abundance-limited from racemization-limited preservation and apply it to the Mars Organic Molecule Analyzer (MOMA) on the ExoMars Rosalind Franklin rover. The model combines cosmic-ray and radiogenic doses with laboratory destruction kinetics and assumed ratios of interconversion to destruction rates. For…

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astro-ph.SRastro-ph.EP

A breath of fresh air: Oxygen enhancement from silicate sublimation during early protostellar evolution

F. J. Ballieux, M. K. McClure, Ł. Tychoniec, L. Francis, A. Egliene, E. A. Bergin, M. R. Van 't Hoff, E. F. Van Dishoeck et al.

Recently, an analog to the t = 0 moment of our Solar System's meteoritic record was identified for the first time around the Class I protostar HOPS-315. Crystalline silicates were found to recondense from SiO gas that cools as it advects upward from a hot thermostat region in the inner midplane. This t=0 moment may be associated with the formation of the first planetesimals in this disk. We explore whether HOPS-68, a Class I protostar with similar properties and system geometries, is engaged in…

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astro-ph.EP

Rattling Resonant Chains with Dynamical Tides and Parametric Resonance Passage

Mohammad Farhat, Eugene Chiang

Close-in sub-Neptunes are born in mean-motion resonant chains that break apart on a timescale of $\sim$100 Myr. If the chains are first ''rattled'' --- have their free eccentricities excited to a few percent --- then breaking occurs on the required timescale. We propose that chains are rattled by internal oscillations tidally driven by the star in the innermost planet. Unlike other proposals, there is no need to invoke any reservoir of planetesimals or external perturbers --- the chain unravels…

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astro-ph.EP

Size, atmospheric, and ring constraints on the large Kuiper belt object (55565) Aya from a stellar occultation

Ko Arimatsu, Hidekazu Hanayama, Satoshi Takita, Fumi Yoshida, Tsutomu Hayamizu, Jun-ichi Watanabe

We aim to constrain the projected size, geometric albedo, possible atmosphere, and possible ring material of the mid-sized trans-Neptunian object (55565) Aya from the stellar occultation of 2024 May 10 (UT). We observed the event from three Japanese sites with high-cadence optical imaging. We combined one positive occultation chord with an informative prior on the shadow centre derived from orbital and astrometric uncertainties, and inferred the body radius with Bayesian Markov chain Monte Carlo…

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astro-ph.EPastro-ph.SR

Tracing the Influence of Distant companions on Exoplanetary Systems (TIDES) I. Highly Eccentric and Misaligned Binary Companions to Hot Jupiters

Marvin Morgan, Jerry W. Xuan, Brendan P. Bowler, Kyle Franson, Michael C. Liu, Konstantin Batygin, Heather A. Knutson, Björn Benneke et al.

The origin of hot Jupiters remains an open question. A significant fraction reside in binary or multiple star systems, suggesting that stellar companions may play an important role in shaping their present-day architectures. However, the orbits of the vast majority of these stellar companions remain poorly constrained, leaving their role in hot Jupiter evolution an open question. We present the Tracing the Influence of Distant companions on Exoplanetary Systems (TIDES) survey, a campaign to map…

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astro-ph.GA

Phase Separation of HI in the Draco Nebula: CNM formation Triggered by Colliding WNM Flows

Yuhi Naruse, Hiroaki Yamamoto, Yamato Matsuzuki, Rin Yamada, Atsushi Nishimura, Toshikazu Onishi

We investigate the thermal phase structures and kinematics of atomic hydrogen (H I) gas in the Draco nebula to clarify how infalling H I evolves toward cold atomic and molecular clouds. Using the DHIGLS H I 21 cm data, we apply the Regularized Optimization for Hyper-Spectral Analysis (ROHSA) algorithm to decompose the emission into spatially coherent Gaussian components, and classify them as warm neutral medium (WNM), lukewarm neutral medium (LNM), and cold neutral medium (CNM). We identify two…

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astro-ph.HEastro-ph.GAastro-ph.SR

IC 1297: The Most Distant Known X-ray Planetary Nebula and One of the Most Luminous

H. Yuan, Q. A. Parker, M. A. Guerrero

We present the first targeted Einstein Probe (EP) X-ray observations of any planetary nebula (PN). Using the onboard Follow-up X-ray Telescope (FXT), we detect X-ray emission within the central region of IC 1297. The spectral analysis yields a plasma temperature of $kT = 0.086^{+0.054}_{-0.058}$ keV ($T\sim1.0 \times 10^{6}$ K), characteristic of shocked wind bubbles in PNe, whereas there is no evidence that its Wolf-Rayet central star emits X-rays. The absorption-corrected X-ray luminosity in t…

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astro-ph.EPastro-ph.SR

Dynamically Coupled Three-dimensional Cloud-Chemistry in Rapidly Rotating Irradiated Atmospheres: an Application to the Compact White Dwarf-Brown Dwarf system ZTFJ0038+2030

Yanhong Lai, Xianyu Tan, Daphne Broski-Laing, Yifan Zhou, Sarah L. Casewell, Jenni R. French, Elspeth K. H. Lee, Joshua D. Lothringer et al.

Clouds and disequilibrium chemistry shape the observable properties of substellar and planetary atmospheres, and JWST time-resolved spectroscopy now enables direct tests of their three-dimensional structures. We present an update to the 3D atmospheric framework ADAM, coupling the dynamical core to a miniature kinetic chemistry scheme (mini-chem) and a saturation-relaxation tracer cloud module. Using this framework, we investigate the atmosphere of the brown dwarf orbiting the white dwarf ZTFJ003…

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astro-ph.EPastro-ph.IM

Experimental evidence for physical alteration of fine regolith on near-Sun asteroids

Jooyeon Geem, Mikael Granvik, Georgios Tsirvoulis, Leonard Schirner, Marianna L. Kemell, Antti Penttila, Axel Hagermann, Athanasia Toliou et al.

The surfaces of airless bodies evolve through processes such as (micro)meteoroid impacts and thermal fatigue, which modify physical properties such as grain size, porosity, and mineral texture. These properties provide clues to surface evolution and are necessary for interpreting telescopic observations. Near-Sun asteroids (NSAs), which reach heliocentric distances of $\lesssim$0.2 au, are notable targets, as their surfaces are likely modified by intense solar radiation. However, experimental st…

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astro-ph.HEastro-ph.COgr-qc

The Promise of Gravitational-Wave Astronomy

Parameswaran Ajith

We review the promise of upcoming gravitational-wave (GW) observations in addressing some of the important open questions in astrophysics and cosmology. A decade after the first direct detection of GWs, the field is entering a transformative phase driven by progressive detector upgrades and the anticipated advent of space-based and next-generation ground-based observatories. These instruments will not only push the distance horizon of GW observations to cosmological redshifts, but will dramatica…

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astro-ph.HEastro-ph.SR

Observational evidence of black hole event horizon from ultra-compact X-ray binaries

Qian-Qi Ma, Wei-Min Gu, Shan-Shan Weng, Mouyuan Sun

The event horizon is the most crucial feature that distinguishes black hole (BH) from all other objects in the universe. However, since no radiation can escape from the event horizon, its direct observational evidence remains lacking. Although both are compact objects, the event horizon leads to differences in the radiative behavior between black hole and neutron star (NS) X-ray binaries. Historically efforts to probe the existence of event horizons revealed that the BH X-ray binaries are fainte…

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physics.plasm-phphysics.space-ph

Effects of Coulomb Collisions on the Structures of Fast Magnetosonic Shocks

Michael B. Farnell, Fan Guo, Yi-Hsin Liu, Xiaocan Li

We present fully kinetic particle-in-cell simulations to demonstrate qualitative effects of binary Coulomb collisions on fast magnetosonic shocks. We find that with sufficiently high collisional frequencies, shock rippling and reformation can be inhibited, leading to stationary, laminar shock fronts. We observe that ion-ion collisions disrupt the motion of particles reflected back upstream that is the key for cyclical reformation. Meanwhile, the electron-ion collisions provide a Spitzer resistiv…

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astro-ph.GAastro-ph.COastro-ph.SR

Non-equilibrium chemistry and radiation hydrodynamics in metal-poor and metal-rich interstellar gas

Shyam H. Menon, Piyush Sharda, Blakesley Burkhart, Tommaso Grassi

We present a flexible implementation of non-equilibrium chemical networks with the $\texttt{KROME}$ framework, coupled to a nonlocal variable Eddington tensor-closed radiation transport scheme ($\texttt{VETTAM}$). Our fiducial network is designed to explicitly capture the formation pathways of important molecular species such as CO, OH, and $\rm H_2O$, intermediaries like $\rm H_3^+$, and the destruction of these species through photon and cosmic-ray dissociation. We validate our scheme through…

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astro-ph.GA

Mergers may not be the main channel for galaxy stellar mass growth at redshift $z\gtrsim5$: Predictions from cosmological hierarchical models and simulations

Hao Fu, Mohammadreza Ayromlou, Francesco Shankar, Lars Hernquist, Andrea Lapi, Daniel Roberts, Feng Yuan, Maulik Bhatt et al.

Mergers are a crucial channel of galaxy growth, but their role relative to star formation remains uncertain at high redshift. Here we investigate merger rates and merger-driven stellar mass assembly for galaxies with stellar mass $M_\star \gtrsim 10^8 \, {\rm M_{\odot}}$ at $z\simeq 5-11$, by combining complementary theoretical approaches within $Λ$CDM. These include the DECODE semi-empirical model, the TNG100 and EAGLE hydrodynamical simulations, and the \textsc{L-Galaxies} semi-analytical mode…

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astro-ph.EPastro-ph.IMcond-mat.mtrl-sci

Elastic Properties of Titan Tholins Revealed by Brillouin Spectroscopy

Mark A. Johnson, Jose R. Montes-Bojorquez, Adis Husic, Xinting Yu, Wenhao Su, Jia-Sen Hu, Ryan Blase, Edward Patrick et al.

Titan tholins, complex organic solids synthesized by simulating photochemical processes in Titan's atmosphere, are widely regarded as analogs to organic surface materials on the Saturnian moon. Their mechanical properties are critical for understanding the evolution of Titan's geomorphology and crustal layering. Here, we report the first direct experimental determination of the complete set of aggregate elastic moduli of tholins using Brillouin spectroscopy. Measurements conducted on tholin powd…

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