研究動向

astro-ph.HE2026年10月8日

Flux Dependence of the 1\,keV Soft X-ray Feature in SAX J1808.4-3658 with \textit{NICER}

Katherine Bruce, Anne M. Lohfink, Jaiverdhan Chauhan, Suchismito Chattopadhyay, Sachiko Tsuruta, Andrew C. Liebmann

We present a systematic X-ray spectral analysis of the 2019 and 2022 outbursts of the accreting millisecond pulsar SAX J1808.4-3658 with extit{NICER} with a particular emphasis on the nature of the longstanding $\sim$1\,keV spectral feature. We report here the first clear evidence that the 0.9-1.0 keV feature varies systematically with source brightness, exhibiting strong correlations with both continuum and blackbody flux. This establishes that the feature is directly coupled to the accretion p…

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astro-ph.GAastro-ph.IM2026年10月8日

Central stellar depletion in the Draco dwarf from Subaru photometry

Eduardo Vitral, Kyosuke S. Sato, Jorge Peñarrubia, Sakurako Okamoto, Veronika Dornan

Dark matter subhaloes are a fundamental prediction of the standard cosmological model, but their low-mass population remains difficult to constrain observationally. Recent work has shown that interactions between subhaloes and dwarf spheroidal galaxies can induce large-scale, out-of-equilibrium fluctuations in their stellar surface density fields, identifiable through Fourier-based statistics. We apply this formalism to deep Subaru photometry of the Draco dwarf, extending previous tests to $\gtr…

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astro-ph.GAastro-ph.CO2026年10月8日

The conditional colour-magnitude distribution: III. A study of galaxy colour- and luminosity-dependent counts-in-cells statistics

Raymon Isaac, Zheng Zheng

The conditional colour-magnitude distribution (CCMD) model connects the galaxy colour-luminosity distribution with dark matter halo mass, which has been constrained in Xu et al. by jointly modelling the two-point correlation functions of a large galaxy sample of the Sloan Digital Sky Survey (SDSS) in fine bins of galaxy colour and luminosity. We test the CCMD model of the galaxy-halo connection using counts-in-cells (CIC) statistics by comparing CCMD model predictions with SDSS measurements for…

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astro-ph.EP2026年10月8日

Stochastic Snowball States in Planetary Climate

Duc Thach Son Vu, John S. Wettlaufer

Motivated by the recent finding of Ji and Abbot (2025) that at moderate eccentricity (0.2--0.3) the planetary Snowball bistability vanishes, we have introduced stochasticity of the orbital eccentricity into a simplified version of the energy balance model of Eisenman and Wettlaufer (2009) to study a general Earth-like planet. The stochastic eccentricity is approximated by two dominant time scales, annual and daily, and is introduced through an analysis of the Kepler equation. We find that, apart…

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astro-ph.SR2026年10月8日

Understanding how Coronal Heating and Magnetic Field Scaling Affect Global Properties of the Low and Middle Corona

Caroline L. Evans, Cooper Downs, Donald Schmit

The magnetic field of the Sun is a key driver of coronal heating and solar wind acceleration. In tandem, these influence the observable morphology of the corona, along with defining the magnetic connectivity and magnitude of open magnetic flux. Here,we investigate how coronal heating affects the magnetothermal state of the 3D global corona by analyzing a series of data-constrained, thermodynamic magnetohydrodynamic (MHD) simulations for solar minimum conditions. We vary the overall heat deposite…

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astro-ph.GAastro-ph.CO2026年10月8日

Mass Proxy Quality of Halo Properties in IllustrisTNG and FLAMINGO Simulations: II. Galaxies, Stars, and Black Holes

Eddie Aljamal, August E. Evrard, Arya Farahi, Dylan Nelson

We study the stellar, black hole, and satellite galaxy populations of group- and cluster-scale halos in the IllustrisTNG, TNG-Cluster, and FLAMINGO cosmological hydrodynamical simulations. We characterize the mass-conditioned scaling relations, covariance, conditional likelihoods, and mass proxy quality (MPQ) of integral properties within $R_{\rm 500c}$: total stellar mass ($M_{\star,\,\rm tot}$), brightest central galaxy stellar mass ($M_{\star,\,\rm BCG}$), intracluster light mass ($M_{\star,\…

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astro-ph.GAastro-ph.CO2026年10月8日

Mass Proxy Quality of Halo Properties in IllustrisTNG and FLAMINGO Simulations: II. Galaxies, Stars, and Black Holes

Eddie Aljamal, August E. Evrard, Arya Farahi, Dylan Nelson

We study the stellar, black hole, and satellite galaxy populations of group- and cluster-scale halos in the IllustrisTNG, TNG-Cluster, and FLAMINGO cosmological hydrodynamical simulations. We characterize the mass-conditioned scaling relations, covariance, conditional likelihoods, and mass proxy quality (MPQ) of integral properties within $R_{\rm 500c}$: total stellar mass ($M_{\star,\,\rm tot}$), brightest central galaxy stellar mass ($M_{\star,\,\rm BCG}$), intracluster light mass ($M_{\star,\…

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gr-qcastro-ph.HEhep-ph2026年10月8日

Observational Signatures of Dyonic Black Holes in Non-Linear Electrodynamics

Sobhan Kazempour, Sichun Sun, Zhiqing He, Chengye Yu

We study the observational features of thin-disk accretion and emission spectra for static, spherically symmetric dyonic black holes in non-linear electrodynamics (NLED). In contrast to classical Maxwell theory, where electromagnetic duality assumes equal charges, the coupling parameters in NLED introduce a new gravitational potential and modify the geometry in the strong-field regime. We also study the kinematic characteristics of particles on circular orbits, such as their angular velocity, sp…

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astro-ph.EPastro-ph.IM2026年10月8日

Systematic non-compliance of satellite megaconstellations with IAU brightness limits

Jack Rayworth, Denis Vida, Pauline Barmby, Peter G. Brown, Sarah Gallagher, Michael J. Mazur, David L. Clark, Maximilian Vovk et al.

Satellite megaconstellations in low Earth orbit interfere with ground-based optical astronomy, but the scale of that interference has been hard to measure. Here we report an uncued photometric survey from a mid-northern latitude site in late 2024 which recorded some 25,000 tracks of 5,118 individual satellites to a limiting visual magnitude of +9.0. The observed population is systematically brighter than the altitude-adjusted limit of order seventh magnitude recommended by the International Astr…

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astro-ph.HEastro-ph.SR2026年10月8日

Shortening the Baseline: Characterising Type Ia Supernovae Using $Δm_{10}(X)$

Joel M. Velasco, Paolo A. Mazzali, Christopher Ashall, Christopher R. Burns, Mark M. Phillips, Lluis Galbany, Nidia Morrell, Maximilian D. Stritzinger et al.

An explorative study of Type Ia Supernovae (SNe Ia) light curves is presented. $Δm_{t}(X)$ decline-rate metrics are used to evaluate alternative characterisations of light curve diversity and the Luminosity-Width Relation (LWR). Using a sample of 362 SNe Ia from the Carnegie Supernova Project (CSP-I and CSP-II), Gaussian Process regression is used to fit $B$- and $g$-band light curves and measure decline-rates across multiple post-maximum timescales. The LWR is calibrated using a clean subsample…

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astro-ph.GA2026年10月8日

The progenitor galaxies of the intracluster light

Rebecca J. Mayes, Facundo A. Gómez, Antonela Monachesi

Intracluster Light (ICL) is a diffuse stellar component of galaxy groups and clusters, bound to the structure's potential rather than to individual galaxies and primarily formed through the stripping and mergers of intermediate-mass galaxies. Its formation and evolution is strongly linked to the central galaxies of groups and clusters, typically the Brightest Cluster Galaxies (BCGs) in clusters. To determine the properties of the progenitor galaxies of the ICL of clusters and groups at redshift…

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astro-ph.IMphysics.ins-det2026年10月8日

Microwave Loss in Low-Temperature ICPCVD Silicon Nitride: Dependence on Precursor Ratio and RF Substrate Bias

H. Athreya, J. Cornelison, M. Mikhailov, R. J. H. van der Kolk, C. Chang, T. Cecil, M. N. Ali, J. A. Zebrowski et al.

Low-loss dielectric films are an important component of superconducting circuits with applications ranging from quantum information to superconducting detectors for astrophysics. In millimeter-wave detector circuits, dielectric loss can be the limiting factor on efficiency and resonator performance. Some advantageous detector fabrication architectures require dielectric deposition at temperatures substantially lower than those conventionally used to achieve low dielectric loss. In this work, we…

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astro-ph.GA2026年10月8日

Pushing Variability Searches to Extreme Dwarf Galaxies with the Vera C. Rubin Observatory Data Preview 2

Fan Zou, W. N. Brandt, Elena Gallo, Franz E. Bauer, Angela Bongiorno, Colin J. Burke, Alister W. Graham, Hengxiao Guo et al.

Galaxies with stellar masses $M_\star<10^8~M_\odot$, hereafter referred to as extreme dwarf galaxies (EDGs), represent one of the least explored regimes in the search for accreting intermediate-mass black holes. Using the recent Vera C. Rubin Observatory Data Preview 2 (DP2; covering 2025-04-25 to 2026-01-06), we present the first systematic search for variability among EDGs in the ELAIS-S1 field, the most extensively observed LSST Deep-Drilling Field in DP2. Applying single-band and cross-band…

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astro-ph.SRastro-ph.GA2026年10月8日

Population II Post-AGB Stars. I. Methodology, Initial Results, and the First Luminosity Function

S. Jean Feeser, Robin Ciardullo, Michael H. Siegel, C. J. Hapich, Akshat S. Chaturvedi

Post-asymptotic giant branch (PAGB) stars share many advantages with the tip of the red giant branch (TRGB) for Population II distance measurements, including minimal internal reddening, easy identification, a solid theoretical foundation, and an expected weak metallicity dependence. At visual wavelengths PAGB stars are the brightest members in old populations, appearing up to $\sim2$ mag brighter than the TRGB and $\sim4$ mag brighter than RR Lyrae stars. Stellar evolution theory predicts that…

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astro-ph.HEgr-qc2026年10月8日

Descalarization bursts from Galactic supramassive neutron stars: a kHz continuous-wave target

José Carlos Olvera M., Daniela D. Doneva, Pablo Cerdá-Durán, José A. Font, Stoytcho S. Yazadjiev

In massive scalar-tensor gravity, a scalarized neutron star must shed its scalar hair as it collapses into a black hole. Using 3D simulations of a realistic rotating progenitor we show that dispersion stretches the emitted burst into a quasi-monochromatic signal in the kHz frequency range lasting $>10^4$ yr and amenable to continuous-wave methods. We find that detecting these signals in directed searches of supernova remnants without a central pulsar requires sensitivity depths of 233--762 $\rm{…

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astro-ph.GA2026年10月8日

First uGMRT Constraints on Rotation Measure in the Radio-Quiet Seyfert Galaxy NGC 4235

Salmoli Ghosh, Preeti Kharb, Janhavi Baghel

We present a multi-frequency polarimetric study of the radio-quiet Seyfert galaxy NGC 4235 using the upgraded Giant Metrewave Radio Telescope (uGMRT), aimed at constraining the Faraday rotation properties of its kpc-scale radio emission. This marks the first-ever analysis of polarization across two frequency bands of the uGMRT and the first constraints on rotation measure (RM) at lower frequencies for a weak radio source (17.1$\pm$1.7 mJy at 1.3 GHz, 27.7$\pm$2.8 mJy at 663 MHz). We detect linea…

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astro-ph.GA2026年10月8日

NGC 4936: abundant multi-phase medium in the central weak X-ray cool core and optically dark H I clouds in the group

Prathamesh Tamhane, Ming Sun, Hao Chen, Thomas Connor, Megan Donahue, Mark Voit, Mpati Ramatsoku, Kokoro Hosogi et al.

We present a multiwavelength analysis of NGC 4936, the central galaxy of a weak cool-core group hosting an unusually large cold/warm gas reservoir. NGC 4936 contains $\sim2\times10^8$ M$_\odot$ of molecular gas in a rotating disk of radius $\sim1$ kpc, but no detected H I, with a $3σ$ upper limit of $1.13\times10^7$ M$_\odot$ within $\sim2.5$ kpc. The resulting $H_2$/H I mass ratio $>17$ is consistent with a predominantly molecular medium in the high-pressure environments of central galaxies. SO…

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astro-ph.GA2026年10月8日

Prevalence of radio Active Galactic Nuclei in galaxy groups since z=3.5 in the COSMOS-Web field

F. Ubertosi, I. Delvecchio, I. Prandoni, G. Toni, G. Zamorani, E. Daddi, M. Gitti, M. Sargent et al.

Radio active galactic nuclei (AGN) are key tracers of kinetic feedback from supermassive black holes. Although the dependence of their triggering on host stellar mass is well known, the impact of the large-scale environment across cosmic time is poorly understood. We investigate the role of the environment in triggering radio AGN activity, while also studying the dependence on stellar mass ($10\leq\log M_{\ast}\,{\rm [M_{\odot}]}\leq11.4$), radio luminosity ($22\leq\log L_{1.4}\,{\rm [W\,Hz^{-1}…

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astro-ph.EPastro-ph.SR2026年10月8日

EK Cha b: multi-tracer detection of a protoplanet candidate in a gas-rich environment

Felipe Alarcón, C. Swastik, Stefano Facchini, Edwin A. Bergin, Gabriele Cugno

Despite sustained community efforts and advances in instrumentation and high-contrast imaging, the search for protoplanets remains difficult, with only two widely accepted systems to date in Class II systems (PDS 70 and WISPIT 2). Here we present the detection of EK Cha b, a new protoplanet candidate, identified through CO emission, millimeter continuum and 0.82 micron broadband photometry, linked to EK Cha, a young late-type M star. The detection of a new protoplanet candidate offers an additio…

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astro-ph.GA2026年10月8日

A "universal" supernova efficiency to drive the HI turbulence in nearby star-forming galaxies

Lauri Sassali, Cecilia Bacchini, Aku Venhola, Giuliano Iorio, Antonino Marasco

The origin of cold gas turbulence in galaxies has long been debated. Supernovae (SNe), the dominant form of stellar feedback, were thought insufficient to sustain it against dissipation, especially in galactic environments with low star formation rates (SFRs). We investigate the origin of the neutral atomic gas (HI) turbulence in dwarf irregular galaxies, a challenging regime of low masses and SFRs. We build on a recent study of spirals showing that disc flaring prolongs the dissipation timescal…

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astro-ph.SRastro-ph.GA2026年10月8日

Atypical White Dwarfs in Open Clusters

David R. Miller, Ilaria Caiazzo, Jeremy Heyl, Pier-Emmanuel Tremblay

Open clusters are powerful laboratories for investigating the formation and evolution of white dwarfs (WDs), as their well-constrained ages link WDs to their progenitor stars. This is particularly valuable for atypical WDs, including magnetic WDs and those with non-hydrogen-dominated spectra, whose origins can be difficult to disentangle in the field. We assemble the largest sample to date of atypical WDs in open clusters: eight non-magnetic WDs with helium-dominated spectra, five with featurele…

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astro-ph.HEastro-ph.COhep-ph2026年10月8日

The Origin of the Fermi Halo-like Emission: A New Model of the Fermi Bubbles

Ilias Cholis, Leo Qiyuan Hu, Yi-Ming Zhong

We study the gamma-ray sky at high latitudes for energies between 0.3 and 900 GeV. We search for a contribution in the high-latitude sky and in the region of the Galactic Stellar Halo that would be beyond known astrophysical emissions, i.e., the galactic diffuse emission, the isotropic mostly extragalactic gamma-ray background, the Fermi Bubbles, Loop I, the contribution from the Galactic Center Excess, and the known point and extended gamma-ray sources detected by the Fermi-LAT Collaboration. W…

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astro-ph.HEastro-ph.SR2026年10月8日

Accreting Neutron Stars in Low-Mass X-ray Binaries

M. C. Baglio, S. E. Motta, A. P. Nitindala, J. Poutanen

Neutron star low-mass X-ray binaries (NS LMXBs) are systems in which a neutron star accretes matter from a Roche-lobe-filling companion via an accretion disc, releasing gravitational energy with an efficiency of order 10-20% of the rest-mass energy. Unlike black holes, neutron stars possess a solid surface and a magnetic field, making NS LMXBs uniquely rich laboratories for high-energy astrophysics and dense-matter physics. In this chapter we review the current understanding of accretion onto ne…

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astro-ph.GA2026年10月8日

Cosmic Duets II. Growth and accretion in Gaia Multi-Peak dual AGN at Cosmic Noon

M. Scialpi, F. Mannucci, D. Izquierdo-Villalba, A. Marconi, J. Singh, M. Volonteri, C. Marconcini, Q. D'Amato et al.

We present the first statistical characterization of the physical properties of Cosmic Duets: dual AGN in the redshift range 0.5 $\leq$ z $\leq$ 3.0 with projected separations of 1-7 kpc, corresponding to systems in which both AGN are expected to reside within the same merger remnant. We analyze the largest homogeneous sample currently available, consisting of 30 spectroscopically confirmed Cosmic Duets selected via the Gaia Multi-Peak technique. Using rest-frame UV-to-optical integral-field spe…

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astro-ph.GA2026年10月8日

A Multi-dimensional Analysis of the Open Clusters NGC 2423 and NGC 2482 with Gaia DR3

W. H. Elsanhoury, Deniz Cennet Çınar, A. Ahmed

We present a homogeneous photometric, astrometric, and kinematic study of the Hyades-like open clusters NGC 2423 and NGC 2482 based on Gaia DR3 data. Cluster memberships are determined using the UPMASK algorithm in the multi-dimensional parameter space of (alpha, delta, parallax, mu_alpha cos(delta), mu_delta), with radial velocities incorporated when available. Gaussian modelling of the astrometric distributions yields mean trigonometric parallaxes of 1.060 +/- 0.035 mas and 0.735 +/- 0.061 mas…

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astro-ph.HE2026年10月8日

Discovery of a Nearby Ultra-fast Magnetic White Dwarf Propeller: Common Pathways to Magnetic Cataclysmic Variables

Antonio C. Rodriguez, Kareem El-Badry, R. Michael Rich, Kevin N. Ortiz Ceballos, Ingrid Pelisoli, Casey J. Law, Kaya Mori, Boris Gaensicke et al.

The fastest spinning white dwarfs (WDs), which approach break-up speeds, are found in close binary systems. In the two known magnetic WD ``propellers'', AE~Aqr and LAMOST J0240+1952, the magnetic WD spins so rapidly that it ejects the material transferred by its Roche-lobe-filling companion rather than accreting it. We report the discovery of the third such system, 1eRASS J042633.5$-$250226 (1eRASS J0426/Valeria), at only 265 pc, identified by combining SRG/eROSITA and \textit{Gaia} data via the…

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astro-ph.HEhep-ph2026年10月8日

Neutrino flavor conversion alters the lepton-emission self-sustained asymmetry in core-collapse supernovae

Noah Roux, Irene Tamborra, Maryna Mesiura

We solve the neutrino equations of motion in a half annulus, accounting for two spatial dimensions. At any location in the annulus, the neutrino momentum is characterized by a polar-angle distribution, two effective azimuthal angles, and an energy distribution. We explore how neutrinos change their flavor while decoupling from matter in the presence of the neutrino-driven hydrodynamical instability LESA (i.e., the Lepton-number Emission Self-sustained Asymmetry) during the stalled-shock phase of…

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astro-ph.HE2026年10月8日

Wind-Fed Magnetic Flux and the Emergence of X-ray Coronae in Active Galactic Nuclei

Rostom Mbarek

We propose a scenario for the onset of radiatively efficient Active Galactic Nuclei (AGN) in which circumnuclear stellar and supernova-driven winds supply mass and partially ordered magnetic flux to a compact disk reservoir around a supermassive black hole. A coherent poloidal component surviving advection to small radii strengthens inward, lowering the gas plasma beta until mean Maxwell stresses overtake MRI turbulence, compress the disk vertically, and open a magnetically dominated wedge above…

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astro-ph.HE2026年10月8日

Exemplary Merging Clusters II: XMM-Newton and Chandra X-ray Observations of MACS J1752.0+4440 and ZwCl 1856.8+6616

K. HyeongHan, K. Finner, W. Lee, E. Silich, W. Forman, C. Jones, A. Tümer, S. Randall et al.

Using deep XMM-Newton and Chandra observations, we compare the double-radio-relic galaxy cluster mergers MACS J1752.0+4440 and ZwCl 1856.8+6616. Both are 1:1 mass-ratio mergers with similar relic separations but differing nearly an order of magnitude in total mass. In MACS J1752.0+4440, the surface-brightness discontinuity at the northeastern relic yields Mach $M_ρ=1.4\pm0.2$, while the temperature jump provides a weaker constraint, corresponding to $M_{kT}\lesssim2.3$ at the $2σ$ level, lower t…

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astro-ph.GAastro-ph.SR2026年10月8日

Global and Local Infall in the ASHES Sample (GLASHES). III. Physical Parameters of Contracting Motion onto Dense Cores in 70 $μ$m Dark Massive Clumps

Kaho Morii, Patricio Sanhueza, Qizhou Zhang, Philip C. Myers, James M. Jackson, Fumiaki Yoshida

Core growth is a key process in high-mass star formation. As part of the GLASHES (Global and Local Infall in the ASHES Sample) survey, we present infall velocities and mass infall rates derived from blue-asymmetric line profiles toward cores embedded in massive 70 \textmu m-dark clumps. Robust Hill5 model fits were obtained for 70 of the 135 cores exhibiting blue-asymmetric profiles, yielding infall velocities of 0.11--1.60 km s$^{-1}$ and mass infall rates ranging from $\sim$10$^{-5}$ to $5\tim…

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