研究動向

astro-ph.GA2026年8月14日

Widefield Arecibo Virgo Extragalactic Survey: II. Characterizing the HI properties and environment of the WAVES South region

V. Partík, R. Taylor, R. Minchin

Context. Galaxy clusters are extreme environments where interactions with the hot intracluster medium drive rapid galaxy evolution. These processes can result in the formation of optically dark gas clouds, as previously observed in Virgo and other clusters. Aims. We investigate the distribution and properties of neutral hydrogen (HI) in two large adjoining regions of the Virgo cluster to understand how the cluster environment influences galaxy transformation. Specifically, we examine the gas con…

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physics.hist-phastro-ph.EPastro-ph.SR2026年8月14日

From the Earth to the Sun

Dieynaba Young

This year marks 360 years since the founding of the French Academy of Sciences. This is the story of the academy's daring 17th century expedition to measure the Earth-sun distance. A truncated version first appeared in National Geographic Magazine; the following is closer to the original draft, with updated information and references.

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physics.data-anastro-ph.COastro-ph.GAcs.LGhep-ex2026年8月14日

Unknown Unknowns: Model Misspecification in Machine Learning for Physics

Juan Cruz-Martinez, Carolina Cuesta-Lazaro, Alexander Held, Michael Kagan

Machine learning is now a central tool for solving inverse problems in particle physics and astronomy. Models are trained on simulation and deployed on real data, raising the question not just of whether they fit, but of whether they are wrong in ways we did not anticipate: the unknown unknowns. This challenge of model misspecification is not unique to machine learning. In physics, misspecification is sometimes exactly what we want to find: new discoveries appear as failures of existing models.…

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astro-ph.HEastro-ph.SR2026年8月13日

Radio Monitoring of Classical Novae using the ASKAP Variable and Slow Transients Survey

Aishani Majumder, David L. Kaplan, Laura N. Driessen, Ashna Gulati, Tara Murphy, Dougal Dobie

We present a search for radio emission from classical novae at 887.5 MHz using data from the Australian SKA Pathfinder Variable And Slow Transient (VAST) survey. We cross-matched 43 optically discovered classical novae that erupted between 2021 September and 2025 November within the 1200-square-degree Galactic survey footprint, and found three which show significant radio emission: V6598 Sgr, V1716 Sco, and V1723 Sco. To analyse their radio light curves, we use both thermal free-free and non-the…

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astro-ph.HEastro-ph.SR2026年8月13日

Radio Monitoring of Classical Novae using the ASKAP Variable and Slow Transients Survey

Aishani Majumder, David L. Kaplan, Laura N. Driessen, Ashna Gulati, Tara Murphy, Dougal Dobie

We present a search for radio emission from classical novae at 887.5 MHz using data from the Australian SKA Pathfinder Variable And Slow Transient (VAST) survey. We cross-matched 43 optically discovered classical novae that erupted between 2021 September and 2025 November within the 1200-square-degree Galactic survey footprint, and found three which show significant radio emission: V6598 Sgr, V1716 Sco, and V1723 Sco. To analyse their radio light curves, we use both thermal free-free and non-the…

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astro-ph.SRastro-ph.HE2026年8月13日

JWST Detects a Dusty AGB-like Source Before the Type Ia-CSM Supernova 2026sqf

Tamás Szalai, Dan Milisavljevic, Noah Zimmer, Braden Garretson, Thomas Moore, Schuyler D. Van Dyk, Anan Lu, Selcuk Topal et al.

Supernova (SN) 2026sqf recently appeared in the nearby face-on spiral galaxy NGC 3310 and has shown signs of strong interaction with a circumstellar medium (CSM). Such intense interaction, rare among nearby SNe, offers a valuable opportunity to reveal details on the origin and nature of its progenitor system. We analyzed the early-phase spectra and light curves (LCs) of SN 2026sqf. The general shapes of the observed spectra, the strengths of the emission lines, and the LC evolution all suggest t…

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astro-ph.GAastro-ph.SR2026年8月13日

Differential Reddening and Extinction Law Analyses of Galactic Open Clusters

Xiaohan Chen, Shu Wang, Xiaodian Chen

Extinction significantly affects open cluster parameters and their use in studies of Galactic structure, yet homogeneous large sample measurements of open cluster extinction properties remain limited. Using Gaia-era open cluster member samples combined with multi-band photometry and stellar parameters, we derive color excesses of member stars and provide the homogeneous characterization of the mean reddening, differential reddening, and color excess ratio (CER) at the cluster scale. Differential…

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astro-ph.GA2026年8月13日

Radio Properties of Narrow-Line and Broad-Line Seyfert 1 Galaxies

K. É. Gabányi, S. Komossa, A. Mezősi, E. Forgács-Dajka, S. Frey

Narrow-line Seyfert 1 (NLS1) galaxies host active galactic nuclei (AGN) with narrow optical emission lines of the broad-line region. This is often explained with a relatively lower mass of the central supermassive black hole and super-Eddington accretion. We compared the radio properties of large samples of NLS1 and broad-line Seyfert 1 (BLS1) galaxies compiled from the Sloan Digital Sky Survey. We cross-matched the NLS1 and BLS1 samples with the Faint Images of the Radio Sky at Twenty-Centimete…

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astro-ph.HEastro-ph.GA2026年8月13日

X-ray Flaring and Variability in NGC 1275, the Heart of the Perseus Cluster

Sarah Ketchum, Jon M. Miller, S. W. Allen, Doyee Byun, Tianyin Hu, Missagh Mehdipour, Veronica Tananko, Xin Xiang et al.

NGC 1275 is the central galaxy in the Perseus Cluster. The active galactic nucleus (AGN) within NGC 1275 is notable for its strong and variable radio activity, tied to the production of radio jets that inflate large bubbles in the hot intracluster medium (ICM). High spatial resolution X-ray imaging can separate the AGN from the bright ICM, but monitoring the mass accretion rate onto the black hole and establishing disk-jet connections in NGC 1275 requires a high cadence. Here, we report on X-ray…

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astro-ph.EPastro-ph.SR2026年8月13日

Stellar tidal systematics in apsidal-motion searches for circumbinary planets: CH Ind and SW CMa

Qunfeng Jiang

Thornton et al. (2026) reported 27 non-transiting circumbinary-planet candidates from excess apsidal motion in TESS eclipsing-binary timings. The classical stellar contribution is sensitive to target-specific radii, apsidal constants $k_2$, and rotation. We re-evaluate two evolved, double-lined eclipsing binaries in that sample: the pulsating system CH Ind and the Am system SW CMa. Their component masses and radii have been measured in dedicated binary studies, allowing the stellar contribution…

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astro-ph.HEastro-ph.GA2026年8月13日

The low luminosity end of Galactic HMXBs with eROSITA: Establishing a luminosity floor for accreting BeXRBs

Aafia Zainab, Philipp Thalhammer, Nico Zalot, Artur Avakyan, Jakob Stierhof, Ekaterina Sokolova-Lapa, Victor Doroshenko, Victoria Grinberg et al.

We present a first look at the Galactic population of heretofore known HMXBs as observed by SRG/eROSITA during its first four surveys. eROSITA's sensitivity of $\sim10^{-13}\,\mathrm{erg}\,\mathrm{s}^{-1}\,\mathrm{cm}^{-2}$, translating to $10^{32}$-$10^{34},\mathrm{erg}\,\mathrm{s}^{-1}$ in luminosity for most known HMXBs in the Milky Way, has thus far never been reached by any wide-area survey instrument. We present the extended log N-log L distribution of known HMXBs reaching down to $10^{32}…

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astro-ph.IMastro-ph.CO2026年8月13日

Optical concept model of the future cosmology project BISOU

Morgane Loquet Le Gall, Bruno Maffei, Pierre Guiot, Creidhe O'Sullivan, Neil Trappe

We present an optical analysis of BISOU (Balloon Interferometer for Spectral Observations of the primordial Universe), an astronomical balloon-borne pathfinder spectrometer developed as part of a preparatory study for a future space mission aiming at measuring spectral distortions of the cosmic microwave background (CMB). The BISOU optical system is based on a differential polarizing Fourier Transform Spectrometer (FTS) that receives inputs from both a sky-facing telescope and an internal calibr…

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astro-ph.EP2026年8月13日

Assessing Planetary Stability and Long-Term Habitability in Nearby Stellar Binaries: 70 Oph, 36 Oph, $γ$ Leo

Alyssa R. Jankowski, Juliette Becker, Catherine A. Clark, Eric E. Mamajek, Jessie L. Christiansen, Yiting Li, Eduardo Bendek, Daniella Gagliuffi et al.

Binary stars are common and have the potential to host habitable planets, which may reside in more complex habitable zones as compared to planets orbiting single stars. In this work, we use numerical simulations to assess the possibility that bright, nearby stellar multiples 36 Oph, 70 Oph, and $γ$ Leo could host habitable planets. We find that for the 36 Oph A/B system and for the 70 Oph A/B system, the stars can support planets residing in permanently habitable zones with low ejection rates an…

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astro-ph.EP2026年8月13日

Assessing Planetary Stability and Long-Term Habitability in Nearby Stellar Binaries: 70 Oph, 36 Oph, $γ$ Leo

Alyssa R. Jankowski, Juliette Becker, Catherine A. Clark, Eric E. Mamajek, Jessie L. Christiansen, Yiting Li, Eduardo Bendek, Daniella Gagliuffi et al.

Binary stars are common and have the potential to host habitable planets, which may reside in more complex habitable zones as compared to planets orbiting single stars. In this work, we use numerical simulations to assess the possibility that bright, nearby stellar multiples 36 Oph, 70 Oph, and $γ$ Leo could host habitable planets. We find that for the 36 Oph A/B system and for the 70 Oph A/B system, the stars can support planets residing in permanently habitable zones with low ejection rates an…

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astro-ph.IMastro-ph.CO2026年8月13日

Optical development of the BISOU breadboard

Morgane Loquet Le Gall, Creidhe O'Sullivan, Bruno Borgo, Clémence De Jabrun, Valentin Sauvage, Neil Trappe, Bruno Maffei

BISOU (Balloon Interferometer for Spectral Observations of the primordial Universe) is an astronomical balloon-borne pathfinder developed as part of a preparatory study for a future space mission aimed at measuring spectral distortions of the cosmic microwave background (CMB). A laboratory breadboard of the instrument is being developed at the Institut d'Astrophysique Spatiale (IAS), enabling the characterization of subsystems and instrument systematic effects, particularly in the optical system…

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astro-ph.IMastro-ph.CO2026年8月13日

FOSSIL's preliminary thermal architecture

Valentin Sauvage, Clémence de Jabrun, Anaïs Besnard, Bruno Borgo, Ivan Charles, Jean-Marc Duval, Bruno Maffei, Sylvain Martin et al.

FOSSIL (FTS fOr CMB Spectral diStortIon expLoration) is a proposed ESA M8 mission tailored to measure the spectral distortions monopole of the Cosmic Microwave Background (CMB) with a sensitivity three orders of magnitude beyond the COBE/FIRAS legacy measurement. Achieving this sensitivity demands an extraordinarily challenging cryogenic architecture: the scientific instrument must be maintained at 4.5 K, while the detector focal plane assembly operates at 50 mK. This paper presents an overview…

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astro-ph.COastro-ph.GA2026年8月13日

Cosmography with DESI-DR1 Cosmic Chronometers: Direct H(z) measurements from Luminous Red Galaxy ages

Carlos A. Álvarez, Marcos M. Cueli, Balakrishna S. Haridasu, Michele Moresco, Martina Torsello, Alessandro Bressan, Lumen Boco, Luigi Danese et al.

Providing robust redshift estimates for almost 3 million luminous red galaxies (LRGs), the Dark Energy Spectroscopic Instrument (DESI) offers a unique opportunity to test the expansion rate of the Universe with independent approaches. We apply the cosmic chronometer method to derive new, independent constraints on the Hubble parameter at 0.3<z<1.2 from the differential age evolution of DESI LRGs. We select spectra applying spectroscopic cuts to ensure sample purity and remove contamination by st…

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astro-ph.EPastro-ph.IM2026年8月13日

A Radon-Transform Perspective on Exoplanet Transits

Shotaro Tada

Transit light curves are usually analyzed under the assumption that the transiting planet has a circular sky-projected silhouette. However, planetary rotation, tides, rings, or atmospheric inhomogeneities can produce non-circular silhouettes. This raises the question of what information transit light curves can provide about the underlying two-dimensional attenuation map. In this paper, we show that, in a simple and transparent limit, the time derivative of the transit light curve during ingress…

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astro-ph.EP2026年8月13日

The atmospheric vertical structure of Uranus and Neptune from thermochemical models: the impact of model assumptions

Thomas Douçot, Ravit Helled, Daniel Kitzmann, Ricardo Hueso, Audrey Vorburger

The composition and temperature-pressure profile of the atmospheres of Uranus and Neptune are not well-determined. As observational data are limited, we often rely on chemical equilibrium computations to infer atmospheric abundances and cloud formation. The inferred atmospheric structures, however, strongly depend on several fundamental assumptions such as the elemental abundances and ratios, the condensation properties of the assumed species, or a reference temperature for the adiabatic structu…

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astro-ph.HE2026年8月13日

Complex Energy-Dependent Behaviour of Quasi-Periodic Oscillation Observed in GRS 1915+105

Vaibhav Sharma, Ranjeev Misra, V. Jithesh, Shivani Chaudhary, Khushi Jirawala, J S Yadav, Pankaj Jain, N J Juris et al.

We present complex energy-resolved properties of quasi-periodic oscillations (QPOs) in the black hole X-ray binary GRS 1915+105 using an observation from the LAXPC instrument onboard AstroSat. Power density spectra (PDSs) are constructed in multiple energy bands and modeled with multi-Lorentzian components to investigate the energy dependence of QPO properties. The QPO frequency shows a modest increase with energy. Dynamic PDS analysis does not reveal clear evidence for time-dependent evolution…

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astro-ph.EPastro-ph.GAastro-ph.SR2026年8月13日

Revisiting gravitational instability in protostellar discs with improved radiative cooling models

Alison K. Young, Ken Rice, Richard Booth, Farzana Meru

Young discs are expected to be significantly more massive than those observed at $>1$ Myr and it is at this earliest stage that planet formation likely begins. Such massive discs may be susceptible to the gravitational instability (GI), therefore we need to determine the disc and stellar properties for which the GI is active to understand its role in early disc evolution and planet formation. Prior work has been limited by model assumptions and inaccuracies due to the complex nature of the therm…

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astro-ph.SR2026年8月13日

TIC 433545934: The first 2+2 type doubly eclipsing binary with extra, mutual eclipses

Tamás Borkovits, Saul A. Rappaport, Petr Zasche, M. Mašek, H. Kučáková, T. Mitnyan, V. B. Kostov, B. P. Powell et al.

In this work we identify and photodynamically analyze TIC 433545934, the very first doubly eclipsing 2+2-type quadruple stellar system, which shows outer eclipses, too. One such outer eclipse was discovered with TESS, which triggered a special interest in this system. Most of the data for this study come from TESS observations, but we also obtained supplemental ground-based photometric measurements for this quadruple system. The eclipse timing variation curves extracted from the TESS and ground-…

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astro-ph.HE2026年8月13日

AT 2024qfm: a luminous fast blue optical transient at a redshift of z = 0.2267 identified by Lasair-ZTF

M. Fulton, S. J. Smartt, S. Srivastav, J. H. Gillanders, J. W. Tweddle, M. E. Huber, M. Nicholl, C. R. Angus et al.

Luminous fast blue optical transients (LFBOTs) emit from x-ray to radio wavelengths, epitomised by the discovery of AT 2018cow in a host galaxy at 65 Mpc. In the following eight years eleven more have been found, at redshifts $0.075 \lesssim z \lesssim0.34$, plus one identified retrospectively from 2016. Here we present the discovery of AT 2024qfm, classified as an LFBOT in a host galaxy at $z = 0.2267 \pm 0.0002$. Its ultraviolet-to-optical luminosity and rapid 13 day fade closely match AT 2018…

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astro-ph.IM2026年8月13日

SNIFFLES I: Intended Emission, Unwanted Emission, and Unintended Radiation from Low-Earth Orbiting Satellites Impacting Radio Astronomy from 1-26 GHz

Balthasar Indermuehle, Liroy Lourenco

We present the first results of SNIFFLES, an ongoing observational programme to characterise intended emission, unwanted emission, and unintended radiation from NGSO systems across common radio astronomy receiver bands from 1-26 GHz (L, S, C, X, and K bands). Using the Australian 22 metre Mopra radio telescope near Coonabarabran, New South Wales, with followup observations from a single dish of the ATCA interferometer and its new BIGCAT backend, we conducted 4629 tracked observations of satellit…

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gr-qcastro-ph.SR2026年8月13日

Temperature effects on white dwarfs in modified gravity

Sofía Vidal, Aneta Wojnar, Laur Järv

In this article we analyze the effects of a finite temperature equation of state on the equilibrium structure of white dwarfs in massive Brans-Dicke theory as well as the symmetron and dilaton screening mechanisms. We compute and present the numerically obtained mass-radius relation, effective gravitational constant as well as radial profiles of the scalar field, pressure and metric within the star. We show that assuming a non-zero temperature effectively results in a larger radius while leaving…

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astro-ph.HE2026年8月13日

Cross-spectral Analysis of the Type-C Quasi-periodic Oscillation Shoulder Component in GX 339-4

Haifan Zhu, Mariano Méndez, Pengcheng Yang, Pei Jin, Candela Bellavita, Federico García, Wei Wang, Diego Altamirano et al.

We revisit Rossi X-ray Timing Explorer (RXTE) observations of GX~339$-$4 during the rising phase of its 2006/2007 outburst and apply a joint power-density-spectrum (PDS)--cross-spectrum (CS) decomposition to the type-C quasi-periodic oscillation (QPO) region. Within this framework, the QPO region is described by a narrow QPO fundamental and a neighboring high-frequency shoulder, whose amplitudes and phase lags can be measured separately. The shoulder is first detected at MJD~54142.04, mainly thr…

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astro-ph.GA2026年8月13日

Gal3D: Superellipsoid Modeling of Radial 3D Galaxy Structure in IllustrisTNG and EAGLE Simulations

Shuai Lu, Min Du

Galaxy morphology and structure are key tracers of galaxy formation and evolution, making accurate measurements of intrinsic three-dimensional (3D) shape essential for linking morphology to galaxy assembly and for comparing numerical simulations. We present Gal3D, a framework that reconstructs smoothed density fields from particle data and quantifies the radial 3D structure of simulated galaxies by fitting superellipsoids to iso-density surfaces. The method recovers axis ratios, orientations, ce…

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astro-ph.EP2026年8月13日

Chondrule formation in the outer disk from the primary three-dimensional chemical composition of CM chondrules

Poula Eyðbjørnsdóttir, Anders Johansen, Elishevah van Kooten

Chondrules and their associated fine-grained rims record key processes in the early protoplanetary disk, yet the links between chondrule chemistry, morphology, and matrix complementarity remain poorly constrained. We investigate the major, minor, and trace element compositions of 66 chondrules and FGRs from the relatively unaltered CM carbonaceous chondrites Asuka 12236, Paris, and Maribo, together with their 3D morphology, using LA-ICP-MS and X-ray tomography. CM chondrules record systematic me…

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astro-ph.SR2026年8月13日

Elemental Composition Evolution during the 2024 September 30 Solar Eruption: A Comparison of Hot and Cool Plasma Components with Solar Orbiter/SPICE, Hinode/EIS, and Chandrayaan-2/XSM

Momchil Molnar, Joseph Plowman, Amir Caspi, Ritesh Patel, Arpit Shrivastav, Tania Varesano, Don Hassler, Ryan French et al.

Solar plasma composition differs between the photosphere and corona over a range of timescales, with preferential enhancement of elements with low first ionization potential (FIP). However, the physical origin of the FIP fractionation remains incompletely understood. Furthermore, during flares, the FIP bias also exhibits rapid changes, associated with fast transport of material with different FIP biases. We present novel observations from Solar Orbiter SPICE and EUI, Hinode/EIS, and Chandrayaan-…

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astro-ph.COastro-ph.GAgr-qchep-ph2026年8月13日

X-ray signals converted from high-frequency gravitational waves emitted by spinning light primordial black hole dark matter

Asuka Ito, Kazunori Kohri

We investigate the detectability of high-frequency gravitational waves from the superradiance of light primordial black hole dark matter through photons converted in the Galactic magnetic field. We find that the signal is significantly enhanced in the X-ray frequency range around $10^{18}$Hz. For clustered initial conditions, future X-ray observations may detect the converted photons from primordial black holes in the mass range $10^{-15}M_{\odot} \sim 10^{-13}M_{\odot}$. Our results indicate th…

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