研究動向

astro-ph.EP2026年9月3日

Properties of Seasonal Ice at Sisyphi Cavi and Implications for Current Modification of Martian Gullies

Apolline Leclef, Mathieu Vincendon, Cateline Lantz, François Andrieu, Marie Ausseresse, John Carter, Susan J. Conway, Marion Massé et al.

Martian gullies are geologically recent landforms that may form either through liquid-water activity and/or through processes involving CO2 ice. We investigated the mechanisms responsible for the formation or modification of these features by focusing on the active site of Sisyphi Cavi (68°S, 1°E), located outside the typical latitude range of gully presence. Using CRISM and OMEGA infrared data, we characterized the composition and physical state of seasonal surface ices to test the relevance of…

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astro-ph.IM2026年9月3日

nufftcf: Fast Auto- and Cross-Correlation Function Estimation for Irregularly-Sampled Time Series via the Non-Uniform FFT

Jean-Eric Campagne

Estimating the auto-correlation function (ACF) and the cross-correlation function (CCF) of sampled series is a standard task across different physics fields, such as astronomy, and environmental sciences. We aim to provide an ACF/CCF estimator primarily designed for irregularly sampled series that is numerically consistent with established, well-validated kernel-weighted definitions, while scaling as O(n log n) rather than O(n^2). nufftcf evaluates the Wiener-Khinchin theorem for irregularly sam…

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astro-ph.HEgr-qc2026年9月3日

A catalogue of insights from the fourth LIGO-Virgo-KAGRA observing run

Christopher P L Berry, Daniel Williams

Over the last decade, gravitational-wave science has developed from an era where a single detection was a Nobel-winning achievement to an (almost) everyday occurrence. The LIGO-Virgo-KAGRA (LVK) Collaboration's flagship scientific results are now their catalogues of detections, which include a comprehensive set of analysis results characterising the astrophysical properties of sources, and their implications for fundamental physics and cosmology. We review discoveries from the fourth observing r…

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astro-ph.IMastro-ph.GA2026年9月3日

Morphology of Radio Sources in Representation Space

Nicolas Baron Perez, Marcus Brüggen, Luisa Lucie-Smith

Understanding radio source morphologies and their classification remains challenging. We previously developed a deep clustering method based on self-supervised learning to classify a subsample of radio sources from the LOFAR Two-meter Sky Survey DR2. This yielded a labelled subset used to fine-tune an ensemble of classifiers. We aim to identify rare morphological classes in a subsample of LoTSS-DR3, which contains > 13 million sources, beyond the 12 classes previously recognised in the DR2 sampl…

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astro-ph.EPastro-ph.GAastro-ph.SR2026年9月3日

Disk survey in the Serpens star-forming region: Environmental effects in nearby star-forming regions

Simin Tong, Nienke van der Marel, Jonathan P. Williams, Alexa R. Anderson

The external environment where protoplanetary disks are embedded regulates disk evolution. External irradiation, which heats and evaporates gas, as well as frequent stellar encounters, which truncate disks, can reduce disk sizes and masses. Disk surveys in nearby star-forming regions with various environments can help us understand how external environments impact disk evolution. The Serpens star-forming region, which is thought to be dense but not highly irradiated by massive stars, is an ideal…

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astro-ph.HE2026年9月3日

The Physics of the Nebular Phase in Black Hole X-ray Binaries: Modelling V404 Cygni

A. Ambrifi, T. Muñoz-Darias, J. A. Fernández-Ontiveros, J. Casares, D. Mata Sánchez, J. H. Matthews

Some of the most extreme galactic black hole transients exhibit a nebular phase at the end of their outbursts. This stage was first identified in the 2015 outburst of V404 Cygni, when it dominated the optical spectrum for ~4 days. It is characterised by exceptionally strong optical emission lines, together with a significant increase in the Balmer decrement. The emission features show broad wings reaching velocities consistent with outflow speeds derived from prominent P-Cygni profiles that prec…

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astro-ph.SR2026年9月3日

New scaling relations from MESA models for mass and radius of subgiant stars: application to Kepler targets

T. Çakır Alsaç, M. Yıldız, S. Örtel

The precise determination of the fundamental parameters of stars is crucial for understanding stellar structure and evolution. In this regard, the asteroseismic parameters of solar-like oscillating stars obtained from space telescopes are very useful for determining the mass ($M$) and radius ($R$) of single stars using classical scaling relations. These relations still need to be improved. In this study, we develop alternative scaling relations based on reference frequencies ($ν_{\rm min}$) due…

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astro-ph.SRphysics.space-ph2026年9月3日

The Role of Preceding CMEs and SIRs in Enhancing Shock Acceleration of Electrons

Xiaomin Chen, Seve Nyberg, Rami Vainio, Immanuel Christopher Jebaraj, Chuan Li, Nina Dresing

The role of large-scale pre-existing interplanetary structures, including preceding coronal mass ejections (CMEs) and stream interaction regions (SIRs), in shaping the shock acceleration environment for energetic electrons remains not fully understood. In this study, we investigate nine interplanetary shocks observed by the Solar Terrestrial Relations Observatory (STEREO) that are associated with significant MeV electron enhancements, as such enhancements are rarely observed at interplanetary sh…

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astro-ph.GAastro-ph.HE2026年9月3日

Rapid Growth of Intermediate-Mass Black Holes through Disk-induced Stellar DisruptionsRapid Growth of Intermediate-Mass Black Holes through Disk-induced Stellar Disruptions

Mengye Wang, Yiqiu Ma, Qingwen Wu, Boyuan Liu, Zijian Wang, Zhili Wang

Dense nuclear star clusters provide unique environments for studying the dynamical interactions between stars and massive black holes. When an accretion disk is present, dissipative star--disk interactions can capture surrounding stars, drive their inward migration, and ultimately lead to disk-induced tidal disruption events\,(dTDEs). The long-term feeding rate from this process, however, cannot be inferred from single-orbit migration estimates alone, as it depends on the coupled evolution of di…

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astro-ph.COastro-ph.GA2026年9月3日

Prospects for probing dark matter with filamentary 21cm emission

Yizhou Liu, Yingjie Jing, Haoran Shi, Huijie Hu

The cosmic web contains most of the matter in the Universe, and its filamentary structure is closely related to the properties of dark matter. Compared with the cold dark matter (CDM) model, warm dark matter (WDM) suppresses the formation of low-mass halos and produces smoother cosmic filaments. In this work, we explore whether filamentary 21cm emission can be used to distinguish between these two dark matter models at $z=4$ and $2.5$. We generate intrinsic 21cm brightness temperature maps from…

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astro-ph.HE2026年9月3日

NuSTAR View of the 2025 Mini-Outburst of the Black Hole X-ray Binary GRS 1739-278: Spectral and Timing Evolution in the Soft State

Arshad Hussain, Umananda Dev Goswami

We present a dedicated timing and spectral analysis of three NuSTAR observations of the Galactic black hole candidate GRS 1739-278 obtained during the decay of its 2025 mini-outburst (September 18-30, 2025). The source is found in a soft, disk-dominated state throughout, with a declining $3$-$79$ keV count rate (from $112.4$ to $99.4$ cts s$^{-1}$), a low and only mildly evolving hardness ratio ($\approx0.14$-$0.16$) and a fractional variability that drops from $3.2\%$ to $1.1\%$; no periodic or…

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astro-ph.HE2026年9月3日

KM3NeT/ARCA stacking search for high-energy neutrino point sources: the case of ultra-luminous infrared galaxies and blazars

The KM3NeT Collaboration

A stacking search for high-energy astrophysical neutrino emission is presented using three candidate source populations: ultra-luminous infrared galaxies and two categories of blazars, specifically high-synchrotron-peaked BL Lacs and extreme blazars. The analysis is based on 336 days of data from the Astroparticle Research with Cosmics in the Abyss component of the KM3NeT research infrastructure (KM3NeT/ARCA), collected with detector configurations comprising 19-21 detection units, yielding 1544…

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astro-ph.GA2026年9月3日

C3PO: A Lyα Emitting Galaxy at $z \sim 9$

Weida Hu, Casey Papovich, Taylor A. Hutchison, Rebecca L. Larson, Pablo Arrabal Haro, Steven L. Finkelstein, Nikko J. Cleri, Lu Shen et al.

We present deep, $>10$ hr, JWST NIRSpec G140M and G395M observations of a previously known galaxy C3PO-8447 at $z=8.99781$. Our new NIRSpec data from the Carbon-3 plus Oxygen (C3PO) survey detect Ly$α$ emission with an escape fraction of $1.5\pm0.3\%$ and a velocity offset of $210\pm80$ km s$^{-1}$, making C3PO-8447 the third Ly$α$ emitting galaxy confirmed at $z\gtrsim 9$. The galaxy has a low stellar mass of $2.2\pm0.1\times 10^7\ M_\odot$, a young stellar age of $1.6\pm0.2$ Myr, and a low oxy…

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astro-ph.EPastro-ph.GAastro-ph.SR2026年9月3日

Trans-Neptunian Object dynamics even better explained by a stellar flyby after 4.5 Gyr of evolution

Susanne Pfalzner, Frank W. Wagner, Marco Bischoff

The Trans-Neptunian objects (TNOs) formed together with the planets from a flat disc of gas and dust but now orbit the Sun mostly on inclined, eccentric orbits. One explanation for the TNOs' orbits is a close flyby of another star. One with a mass of $M_p =$0.8 Msun at $q_p =$ 110 au and $i_p =$70° fits the observations. However, such close encounters were more frequent when the Sun was young and still part of its birth cluster. Assuming that the flyby happened then, we use numerical $N$-body si…

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astro-ph.EPastro-ph.IM2026年9月3日

Effect of stellar spot-only spectral lines in high-resolution transit spectroscopy

W. Dethier, E. Cristo, O. D. S. Demangeon, J. P. Lucero, N. C. Santos, B. Tessore

We investigate how a representative single spectral line present only in a stellar spot can introduce distortions in high-resolution planetary absorption spectra. Specifically, we assess whether such spot-induced features may resemble planetary atmospheric absorption and the observational or stellar conditions under which they become significant. Using the SOAPv4 code, we simulated transit observations of an atmosphere-less planet across a star with a spot containing an additional absorption lin…

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astro-ph.EP2026年9月3日

Dynamically favorable hosts for submoons around Jupiter and Saturn

Ryan Dahoumane, Valéry Lainey, Kevin Baillié

The long-term stability of small bodies orbiting natural satellites (submoons) in the Solar System has been previously investigated using an analytical approximation of a three-body problem, focusing mainly on tidal forces and neglecting other perturbations. This approach suggests that submoons around most of the regular satellites in the Solar System could be stable. However, no such object has been detected to date. In this work, we extend these previous results by numerically testing the surv…

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astro-ph.GAastro-ph.CO2026年9月3日

Bright star-forming galaxies naturally forming at z>10 in the Shark semi-analytic model

Claudia D. P. Lagos, Angel Chandro-Gomez, Chris Power, Aaron S. G. Robotham

The James Webb Space Telescope (JWST) has unveiled the existence of numerous z>10 bright ultraviolet (UV) galaxies, potentially challenging galaxy formation models in a Lambda Cold Dark Matter (LCDM) universe. Modifications to star formation and stellar feedback models have been suggested to alleviate the tension. However, the fundamental challenge is to design a galaxy formation model that simultaneously reproduces observations from z=0 to those at the highest redshifts. Here, we present predic…

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astro-ph.GA2026年9月3日

Magnetic Fields in Massive Star-forming Regions (MagMaR). XII. Radiative Torque Alignment and Disruption in NGC6334I

Vineet Rawat, Thiem Hoang, Patricio Sanhueza, Ian W. Stephens, Manuel Fernández López, Paulo Cortés, Jihye Hwang, Junhao Liu et al.

Intense radiation from high-mass stars is expected to significantly affect dust grain alignment and evolution through RAdiative Torques (RATs). We investigate this effect in a massive star-forming region, NGC6334I, using 1.2 mm dust continuum polarization observations from the Atacama Large Millimeter/submillimeter Array. The polarization fraction spans from $\lesssim1\%$ to $\sim10\%$ and decreases with increasing column density, remaining below $2\%$ in dense cores despite high temperatures ($…

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astro-ph.HEastro-ph.IM2026年9月3日

Gamma-Ray Bursts and Optical Brightness: Insights from Swift Satellite

Istvan I. Racz, Yasmin Nehme, Lajos G. Balazs

During the examination of optical properties of gamma-ray bursts (GRBs) measured during the life of the Neil Gehrels Swift Observatory satellite, significant discoveries were made. While the satellite measures gamma, X-ray, and optical data simultaneously, in many cases, only an upper limit is established in the optical domain. Hence, survival analysis, a.k.a. dependability modelling, was necessary, serving as a tool for studying samples where some cases are bound only by the upper limit, as men…

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astro-ph.HE2026年9月3日

The Jet Properties and Accretion Regime for the Blazar Sequence

Qingchen Long

The puzzling bimodality displayed by blazars on the broad-band spectral indices ($α_{\rm ro}-α_{\rm ox}$) plane is still an open question. To investigate its physical origin, we compiled a sample comprising 136 flat-spectrum radio quasars (FSRQs), 64 low-synchrotron-peaked BL Lac objects (LBLs), 39 intermediate-synchrotron-peaked BL Lac objects (IBLs), and 105 high-synchrotron-peaked BL Lac objects (HBLs). Our results show that (FSRQs+LBLs)$\rightarrow$IBLs$\rightarrow$HBLs follow a \reflectbox{…

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astro-ph.GAhep-ex2026年9月3日

Constraints on mu-variations from the methanol CH3OH thermal lines in the Galaxy at galactocentric distances of 1.5 < D_GC < 13 kpc

A. I. Shtein, J. S. Vorotyntseva, S. A. Levshakov

In this study, constraints are set on hypothetical variations of the fundamental physical constant mu = m_e/m_p - the electron-to-proton mass ratio - based on thermal emission lines of E-methanol (CH3OH) in the 216-220 GHz frequency range. Molecular spectra toward seven massive clouds located across a wide range of galactocentric distances (1.5 = (0.5+/-0.5)*10^(-7) does not indicate statistically significant changes in mu at the 1 sigma confidence level of 5*10^(-8), which is in good agreement…

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astro-ph.IMhep-ex2026年9月3日

Reconstruction of Shower-like Events in NEON Using Likelihood and Graph Neural Network Methods

Sujie Lin, Weiqin Huang, Yihan Liu, Chengyu Shao, Lili Yang, Huiming Zhang

The Neutrino Observatory in the Nanhai (NEON) is a proposed deep-sea neutrino telescope deployed in the South China Sea. Accurate reconstruction of shower-like events is crucial for neutrino energy measurements and multi-messenger astronomy, yet it poses significant challenges due to seawater optical attenuation, irregular detector geometry, and substantial $^{40}\mathrm{K}$ ambient background. In this work, we present the first comprehensive reconstruction framework for shower-like events in NE…

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astro-ph.GA2026年9月3日

Search for intranight optical variability in a large sample of intermediate-mass black holes

Himanshu Sharma, Gopal-Krishna, Vibhore Negi, Hum Chand, Krishan Chand, Anshul Kumar Sharma

Using the extensive archival database of the Zwicky Transient Facility (ZTF) survey, we have investigated intranight optical variability (INOV) in a large sample of low-mass active galactic nuclei (LMAGN) powered by intermediate-mass black holes (IMBHs). After applying a sequence of well-motivated selection filters, we constructed an unbiased, representative sample of 62 IMBHs for which $r$-band intranight photometric sequences are available in the ZTF database, yielding 167 sessions with a mini…

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astro-ph.IM2026年9月3日

Night-sky emission correction techniques for high-resolution spectroscopy: Demonstration with NIRPS

Avidaan Srivastava, François Bouchy, Xavier Dumusque, Étienne Artigau, René Doyon, Neil J. Cook, Danuta Sosnowska, Flavie Bélanger et al.

Ground-based spectrographs operating in the near-infrared (NIR) regime are hampered by various absorption and emission features of Earth's atmosphere. While considerable attention has been paid to mitigating telluric absorption, correcting telluric emission features remains non-trivial and can significantly affect the observation of faint targets. We aim to develop and implement automated algorithms for sky background emission correction in the context of high-resolution spectroscopy. These empi…

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astro-ph.IM2026年9月3日

3.5-meter Segmented-Mirror Robotic Space Telescope Mission White Paper V. Key Scientific Mission: Compact-Object Time-Domain Science

Juhan Kim, Yong-Woo Kang, Sang Hyun Lee, Jeong-Yeol Han, Sungwook E. Hong, Bongkon Moon, Donguk Song, Juhyung Kang et al.

An isolated compact object retains the point-source resolving power of the space-based slitless spectrograph. The baseline wavelength range is 0.2--1.5 $μ$m. The planning baseline uses $R \simeq 1000$ for broad and faint transient spectra and reserves selectable bands at $R \simeq 5000$ for accretion-disk profiles, velocity structure, and precision line ratios. Broad features can be measured after binning the native $R \simeq 5000$ data to lower resolution. Rapid-response spectroscopy follows gr…

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astro-ph.IM2026年9月3日

3.5-meter Segmented-Mirror Robotic Space Telescope Mission White Paper IV. Key Scientific Mission: Solar-System Small Bodies and Planetary Defense

Juhan Kim, Yong-Woo Kang, Sang Hyun Lee, Jeong-Yeol Han, Sungwook E. Hong, Bongkon Moon, Donguk Song, Juhyung Kang et al.

The baseline 0.2--1.5 $μ$m observatory provides rapid-response astrometry, visible and near-infrared taxonomy, rotation and phase curves, recovery, and long-arc orbit improvement for near-Earth objects and other small bodies. The instrument study also evaluates calibrated throughput to 2.70 $μ$m with a 3.0 $μ$m operational band-edge goal. A reduction to 2.5 $μ$m remains the formal engineering off-ramp if thermal, detector, cooling, mass, power, or cost constraints require it. The 3.5-meter Segme…

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astro-ph.GA2026年9月3日

Evolution of Virial Clouds - II: From the Formation of First Stars up to their Explosion

Noraiz Tahir, Asghar Qadir, Francesco De Paolis, Noor Fatima

The existence of cold gas and dust clouds close to the cosmic microwave background (CMB) temperature was proposed as a potential repository for a significant fraction of the missing baryons in galactic halos. While the evolution of the virial clouds from the last scattering surface (LSS) ($z=1100$) up to the formation of Population III (Pop III) stars ($z=48$) was studied in [N. Tahir, A. Qadir, M. Sakhi, \& F. De Paolis, The Euro. Phys. Jour. C 81, 827 (2021)] (Paper I), the subsequent evolutio…

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gr-qcastro-ph.HEastro-ph.IMcs.LGphysics.comp-ph2026年9月3日

Introducing SINFONIA: Symplectic, slimplectic and Magnusian (Neural) Flows for Orbital Numerical Integration and Acceleration

Lidia J. Gomes Da Silva

Long-duration gravitational-wave modelling must resolve fast orbital motion together with slow dissipative evolution while preventing small numerical errors from accumulating into secular phase drift. Here we ask whether the finite-time evolution map itself can be learned as an explicit, differentiable, structure-preserving object and then repeatedly composed through a complete inspiral. We construct three neural-flow architectures: a symplectic and slimplectic flow on Galley's doubled phase spa…

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astro-ph.SRastro-ph.GA2026年9月3日

NGC 1901: A new benchmark cluster for gyrochronology in the TESS Southern continuous viewing zone

Mara Bernizzoni, Timothy R. Bedding, Prasad Mani, Luke G. Bouma, Courtney L. Crawford, Jason Lee Curtis, Benjamin T. Montet, Samir Nepal et al.

We use Gaia DR3 astrometry and TESS time-series photometry to study NGC 1901, a sparse open cluster in the TESS Southern continuous viewing zone, that has been neglected due to its proximity on the sky to the Large Magellanic Cloud. We refine its membership list and measure rotation periods for 32 high-confidence rotating stars. By applying the gyro-interp empirical model, we calculate a gyrochronal age of 830 $\pm$ 50 Myr. Because NGC 1901 possesses a sub-solar metallicity of [Fe/H]$\approx -0.…

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astro-ph.SRphysics.space-ph2026年9月3日

Bifurcations in the Heliosphere: Global-scale Coronal Pseudostreamer Evolution and the Creation of Secondary Heliospheric Current Sheets

Lizet S. Casillas, Benjamin J. Lynch, Victor Réville, Olga A. Panasenco, Marco Velli

The heliospheric current sheet (HCS) is the boundary between open magnetic fields of opposite polarity in the solar wind that connect back to their respective open flux regions in the corona. The HCS is often described as a disc-like sheet warped by the combined effects of the inclination of the magnetic equator on the Sun, solar rotation, and solar wind expansion. The HCS is an extension of the helmet streamer belt-the closed-flux region resulting from the global dipole component of the observe…

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