研究動向

astro-ph.SRastro-ph.GA2026年10月8日

Kinematic and Dynamical Properties of Solar Neighborhood White Dwarfs from SDSS DR19 and Gaia DR3

O. Caliskan, M. Kilic, S. Bilir

We present a comprehensive kinematic and dynamical analysis of 5,837 DA white dwarfs with SDSS DR19 spectroscopy and Gaia DR3 astrometry. Using complementary spatial distributions, kinematic properties, and orbital parameters, we show that the sample is overwhelmingly dominated by the thin disk, with only minor contributions from the thick disk and the halo. Velocity dispersions and orbital eccentricities increase systematically from the thin disk to the halo, reflecting progressively hotter Gal…

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gr-qcastro-ph.COastro-ph.HEastro-ph.IMnucl-th2026年10月8日

Impact of site-dependent noise configurations on Einstein Telescope science at low frequency

Francesco Crescimbeni, Matteo Di Giovanni, Davide Rozza, Andrea Contu, Alessandro Cardini, Domenico D'Urso, Carlo Giunchi, Luca Naticchioni et al.

We investigate how site-dependent Newtonian noise configurations affect the scientific performance of the Einstein Telescope (ET), a third-generation gravitational-wave observatory. We compare the baseline triangular and 2L detector geometries, with arm lengths of 10km and 15km, respectively, under three site-dependent noise scenarios constructed from measurements in the Euregio Meuse-Rhine region, Lausitz, and Sardinia. The differences among the adopted sensitivities are concentrated mainly bel…

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gr-qcastro-ph.COastro-ph.HE2026年10月8日

A weakly modelled view of the joint compact-binary mass plane: population structure and spectral-siren cosmology

Viola De Renzis, Alessandro Agapito, Michele Mancarella

We introduce a flexible mixture model for the joint source-frame component-mass distribution of compact binaries, inferred simultaneously with cosmology, together with a framework that identifies structures in the reconstructed density, quantifying their posterior stability, local prominence, and cosmological relevance. Applied to GWTC-5.0, the workflow clarifies several familiar and emergent structures. The $\sim35~M_\odot$ feature is classified as a clear near-equal-mass peak despite an ambigu…

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astro-ph.HEastro-ph.GA2026年10月8日

Widespread steep X-ray spectra of luminous $z\simeq5.85-7.5$ quasars and their implications for future X-ray surveys

A. Tortosa, L. Zappacosta, E. Piconcelli, I. Saccheo, G. Lanzuisi, E. Bertola, F. Vito, M. Bischetti et al.

Luminous quasars (QSOs) at the Epoch of Reionization (EoR, $z\gtrsim6$) host billion-solar-mass black holes assembled within the first Gyr of cosmic time. Their X-ray emission probes the innermost accreting regions and constrains the physical state of the corona during early supermassive black hole (SMBH) growth. Previous results from the HYPerluminous quasars at the Epoch of ReionizatION (HYPERION) sample of $z \gtrsim 6$ QSOs, powered by the most rapidly accreted SMBHs, suggested a link betwee…

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astro-ph.HEastro-ph.GA2026年10月8日

Widespread steep X-ray spectra of luminous $z\simeq5.85-7.5$ quasars and their implications for future X-ray surveys

A. Tortosa, L. Zappacosta, E. Piconcelli, I. Saccheo, G. Lanzuisi, E. Bertola, F. Vito, M. Bischetti et al.

Luminous quasars (QSOs) at the Epoch of Reionization (EoR, $z\gtrsim6$) host billion-solar-mass black holes assembled within the first Gyr of cosmic time. Their X-ray emission probes the innermost accreting regions and constrains the physical state of the corona during early supermassive black hole (SMBH) growth. Previous results from the HYPerluminous quasars at the Epoch of ReionizatION (HYPERION) sample of $z \gtrsim 6$ QSOs, powered by the most rapidly accreted SMBHs, suggested a link betwee…

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astro-ph.HEastro-ph.GA2026年10月8日

Widespread steep X-ray spectra of luminous $z\simeq5.85-7.6$ quasars and their implications for future X-ray surveys

A. Tortosa, L. Zappacosta, E. Piconcelli, I. Saccheo, G. Lanzuisi, E. Bertola, F. Vito, M. Bischetti et al.

Luminous quasars (QSOs) at the Epoch of Reionization (EoR, $z\gtrsim6$) host billion-solar-mass black holes assembled within the first Gyr of cosmic time. Their X-ray emission probes the innermost accreting regions and constrains the physical state of the corona during early supermassive black hole (SMBH) growth. Previous results from the HYPerluminous quasars at the Epoch of ReionizatION (HYPERION) sample of $z \gtrsim 6$ QSOs, powered by the most rapidly accreted SMBHs, suggested a link betwee…

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astro-ph.IMastro-ph.HE2026年10月8日

BOLT: Imaging Lightning and Terrestrial Gamma-ray Flashes at the Pierre Auger Observatory

Eric-Teunis de Boone, for the Pierre Auger Collaboration

Lightning-related phenomena are known to interact with and influence all detector systems of the Pierre Auger Observatory. Notably, the Surface Detector has recorded unique signals associated with Terrestrial Gamma-ray Flashes (TGFs), which are rare phenomena linked to the initial processes of lightning. Studying TGFs in coincidence with their parent lightning discharges helps to constrain the mechanisms responsible for their production, providing key insights into how these high-energy emission…

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astro-ph.HE2026年10月8日

The NANOGrav 15 yr Dataset: Modified Functional Forms for Profile-Evolution Time Delays in Pulsar Timing Models

Sofia V. Sosa Fiscella, Michael T. Lam, Olivia West, Ruggero Valdata, Gabriella Agazie, Akash Anumarlapudi, Anne M. Archibald, Zaven Arzoumanian et al.

Radio pulsars exhibit frequency-dependent variations in the shape of their pulse profiles that introduce systematic delays in the observed pulse times of arrival (TOA) across an observing band. The North American Nanohertz Observatory for Gravitational Waves (NANOGrav) models these delays using a frequency-dependent (FD) log-polynomial function whose coefficients are fit to TOA measurements at different radio frequencies. However, FD parameters are prone to absorbing power from other chromatic e…

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astro-ph.HEastro-ph.IM2026年10月8日

Deep Learning for Cherenkov Astronomy: Performance of GammaLearn on LST-1

G. Grolleron, C. Plard, M. Dell'aiera, T. François, V. Pollet, J. Talpaert, S. Caroff, T. Vuillaume on behalf of the CTAO-LST Project et al.

The Cherenkov Telescope Array Observatory (CTAO) marks the next generation of Imaging Atmospheric Cherenkov Telescopes (IACTs), offering a sensitivity improvement of up to a factor of 10 over current instruments. Its first prototype, the Large-Sized Telescope (LST-1), is already in operation at the Roque de los Muchachos Observatory in La Palma, Spain. Deep learning methods have shown significant promise in reconstructing key properties of incident particles, such as energy, arrival direction, a…

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astro-ph.GA2026年10月8日

A Decade-Scale Ionization Echo of Black-Hole Accretion in Galactic Nuclei

Wei-Jian Guo, Shuo Zhai, Chen Hu, David M. Alexander, Bin Luo, Pu Du, Matthew J. Temple, Leah K. Morabito et al.

Circumnuclear structures in active galactic nuclei respond to accretion variability over different spatial and temporal scales, but whether compact narrow-line gas responds on decade timescales has not been systematically established. We use repeat Sloan Digital Sky Survey and Dark Energy Spectroscopic Instrument spectroscopy of 473 variability-selected galactic nuclei with evidence for recent nuclear brightening. We identify 19 sources whose narrow [O III] $\lambda5007$ flux increased by more t…

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astro-ph.SRastro-ph.GA2026年10月8日

Photometric and Spectroscopic Study of Young Stellar Objects in IC 1848E Region

Shubham Yadav, Neelam Panwar, Lalita Sharma, C. Rishi

We present a comprehensive analysis combining multi-epoch mid-infrared (MIR) photometric and optical spectroscopic observations of young stellar candidates associated with elongated, elephant trunk-like structures (ETLSs) in the IC 1848E star-forming region. A sample of 15 candidate YSOs, initially identified by Chauhan et al. (2011), was investigated using multi-epoch NEOWISE $W1$ and $W2$ photometry to characterize their variability properties. After imposing stringent positional and photometr…

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astro-ph.GAastro-ph.HE2026年10月8日

Changing-look Active Galactic Nuclei from the Dark Energy Spectroscopic Instrument. VII. Testing Disk-Corona Diagnostics with eROSITA

Wei-Jian Guo, Shuo Zhai, Zhu-Heng Yao, Huaqing Cheng, Jingwei Hu, Jun-Jie Jin

Changing-look active galactic nuclei (CL-AGN) have been proposed to follow an X-ray-binary-like, V-shaped relation between the optical/ultraviolet-to-X-ray spectral slope, $α_{\rm OX}$, and the Eddington ratio, $λ_{\rm Edd}\equiv L_{\rm bol}/L_{\rm Edd}$. We test this interpretation using CL-AGN selected from the Dark Energy Spectroscopic Instrument (DESI) and control samples matched to the eROSITA all-sky survey (eRASS). We find that the apparent positive correlation between $α_{\rm OX}$ and th…

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astro-ph.SRastro-ph.IM2026年10月8日

ROSE (Red-giant Oscillations Spectra Estimator): A Modular Machine-Learning Framework for Automated Asteroseismic Characterisation. I. $ν_{\max}$ and $Δν$ from TESS

Nipun Ghanghas, Dinil B. Palakkatharappil, Rafael A. Garcia, Shravan Hanasoge

Space-based photometry from Kepler and TESS has delivered oscillation spectra for hundreds of thousands of red giants, and PLATO and the Roman Galactic Bulge Time-Domain Survey will add more. We present ROSE, a modular machine-learning framework for automated asteroseismic characterisation of red giants, and apply two of its modules to the frequency of maximum oscillation power, $ν_{\rm max}$, and the large frequency separation, $Δν$. Each module is a neural network bundled with its own preproce…

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astro-ph.EPastro-ph.GA2026年10月8日

Two Low-Mass-Ratio Microlensing Planets from High-Magnification Events: KMT-2021-BLG-0247 and MOA-2023-BLG-169

Kansuke Nunota, Andrew Gould, Takahiro Sumi, Ian A. Bond, Jennifer C. Yee, Valerio Bozza, Fumio Abe, David P. Bennett et al.

We present an analysis of two planetary microlensing events, KMT-2021-BLG-0247 and MOA-2023-BLG-169, both of which exhibit high magnifications and low planet--host mass ratios, but with markedly different levels of parameter constraint. For KMT-2021-BLG-0247, the finite-source effect and microlens parallax are both clearly detected, leading to unusually tight constraints on the physical properties of the lens system. The host mass and lens distance are approximately $M_{\rm L}=0.9\pm0.1\,M_\odot…

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astro-ph.EPastro-ph.GA2026年10月8日

Two Low-Mass-Ratio Microlensing Planets from High-Magnification Events: KMT-2021-BLG-0247 and MOA-2023-BLG-169

Kansuke Nunota, Andrew Gould, Takahiro Sumi, Ian A. Bond, Jennifer C. Yee, Valerio Bozza, Fumio Abe, David P. Bennett et al.

We present an analysis of two planetary microlensing events, KMT-2021-BLG-0247 and MOA-2023-BLG-169, both of which exhibit high magnifications and low planet--host mass ratios, but with markedly different levels of parameter constraint. For KMT-2021-BLG-0247, the finite-source effect and microlens parallax are both clearly detected, leading to unusually tight constraints on the physical properties of the lens system. The host mass and lens distance are approximately $M_{\rm L}=0.9\pm0.1\,M_\odot…

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gr-qcastro-ph.HEhep-th2026年10月8日

Analytic parity-violating greybody factors of a dynamical Chern-Simons black hole

Abhishek Rout

We study the low-frequency scattering of gravitational and pseudoscalar waves off a non-rotating black hole in dynamical Chern-Simons (dCS) gravity, where the axial (odd-parity) gravitational sector is irreducibly coupled to the dynamical pseudoscalar while the polar sector remains general relativistic. Working to first order in the dimensionless coupling zeta = (ell_CS/M)^4 and using matched asymptotic expansions, we obtain an exact closed form for the graviton-to-pseudoscalar conversion probab…

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astro-ph.HE2026年10月8日

A relativistic inflow candidate in a quasar at cosmic noon

Yerong Xu, Xiurui Zhao, Elena Bertola, Valentina Braito, Francesca Civano, Luca Comisso, Luigi Gallo, Vittoria E. Gianolli et al.

Cosmic noon ($z\sim2$) marks the peak epoch of cosmic star formation and black hole accretion activity, where strong accretion and outflows are expected. We report two candidate absorption features in the \textit{XMM-Newton} spectrum of the quasar WISEA~J094835.95+432302.6 at $z=1.893$. Two redshifted features occur at rest-frame energies of $\sim4.65$ and $\sim5.75$keV with confidence levels of 99.3% and 94.1%, respectively, estimated from Monte Carlo (MC) simulations considering the look-elsew…

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astro-ph.GAastro-ph.HE2026年10月8日

A Gravitationally Lensed Low-Luminosity AGN From The Cosmic Noon

Marko Mićić, Olivia Holmes, Xinyu Dai, Kevin Hainline, Haikun Xue, Zijun Gao

Strong gravitational lensing provides a unique tool of studying intrinsically faint high-redshift active galactic nuclei (AGN). In particular, low-luminosity AGN (LLAGN) can probe black-hole growth in low-mass galaxies that current X-ray surveys cannot otherwise access. We investigate the nature and physical properties of a faint X-ray source triply imaged by the galaxy cluster SDSS J2243$-$0935, and determine whether the source hosts an AGN. We combine archival Hubble Space Telescope imaging an…

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astro-ph.GAastro-ph.IM2026年10月8日

IMFIT-MW: Multiwavelength photometric decomposition with IMFIT

Ilia V. Chugunov

Photometric decomposition is often used to study galaxy structure by modelling surface brightness distribution in its components. However, most of the relevant codes are designed for single-band analysis. I present IMFIT-MW: a lightweight, open source Python tool that extends IMFIT capabilities to simultaneously model multiwavelength images. IMFIT-MW is able to set shared parameters between filters and to impose smooth variation of them with wavelength. IMFIT-MW achieves this by using IMFIT to p…

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astro-ph.EPastro-ph.SR2026年10月7日

A Recurrent Infrared Modulation in the Warm Post-impact Debris Disk NGC 2547 ID8

Xiaodian Chen, Shu Wang, Zhuochao Huang

Extreme debris disks are signposts of violent rocky collisions, but it remains unclear whether their mid-infrared variability traces transient dust clouds or longer-lived post-impact reservoirs. We analyze a 19 yr mid-infrared record of the young solar analog NGC 2547 ID8, combining four spectra from 2007-2024 with 3-5 micron monitoring through 2026. The optically thin mineral surface remains compositionally stable: broad fits spanning multiple grain sizes give 550-577 K, and a common-basis deco…

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astro-ph.GA2026年10月7日

MUSE-ALMA Haloes XVI: a census of the condensed baryons in z~0.5 HI absorption-selected galaxies

T. O'Beirne, C. Péroux, M. Zwaan, C. Barfety, V. Bollo, J. Chen, A. L. Danhaive, N. M. Förster Schreiber et al.

We use the MUSE-ALMA Haloes sample to build a census of the condensed baryons (stars and cold gas) to study the multiphase interstellar medium and circumgalactic medium (CGM). The sample includes 79 gas-rich galaxies at 0.2<z<1.2 located near strong HI Ly-alpha absorbers along quasar sightlines within projected separations of ~5-270 kpc and radial velocity separations of up to 500 km/s. HST spectroscopy characterises the absorbers, while HST imaging, MUSE and ALMA observations trace the stars, i…

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astro-ph.GA2026年10月7日

MUSE-ALMA Haloes XV: Cold molecular, ionised, and stellar kinematics of HI-rich galaxies at z $\sim$ 0.5

C. Barfety, N. M. Förster Schreiber, C. Péroux, L. J. Tacconi, J. Chen, S. Weng, V. Bollo, T. O'Beirne et al.

Spatially resolved galaxy kinematics are well studied at z $\sim$ 0 and z > 1, revealing that disks are common out to z $\sim3-6$, albeit with higher velocity dispersions. z $\sim$ 0.5 marks a key transition in the drivers of disk turbulence and baryonic-dark matter mass budgets, yet multi-tracer resolved kinematic studies remain rare beyond the local Universe. We exploit a unique dataset combining ALMA CO observations with MUSE ionised gas and stellar continuum data to study the resolved kinema…

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astro-ph.GA2026年10月7日

MUSE-ALMA Haloes XIV: The ALMA Large Programme Data Release

Céline Péroux, Jianhang Chen, Victoria Bollo, Tamsyn O'Beirne, Capucine Barfety, Simon Weng, Ramona Augustin, Benedetta Casavecchia et al.

The interactions between gas and galaxies are of paramount importance to our understanding of structure formation. A fundamental element of such baryon cycle studies is a complete census of the condensed matter (stars and cold gas) in both galaxies and their immediate surroundings, the so-called circumgalactic medium. Of particular importance are the processes of converting molecular gas into stars and deciphering whether this <100K gas is tracing gas flows. The MUSE-ALMA Haloes survey has assem…

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astro-ph.HEastro-ph.GAgr-qc2026年10月7日

Quasi-periodic eruption spectral-timing: EMRIs crossing warped accretion disks

Joheen Chakraborty, Andrew Mummery, Eliot Quataert, Riccardo Arcodia, Itai Linial, Erin Kara

Quasi-periodic eruptions (QPEs) are repeating X-ray transients from galactic nuclei potentially caused by a stellar-mass orbiter repeatedly colliding with the accretion disk of a supermassive black hole (SMBH) in an extreme mass-ratio inspiral (EMRI). In this picture, the eruption arrival times encode the orbit and its relativistic precessions, while the quiescent spectral energy distribution (SED) probes the same disk and SMBH, providing two independent constraints on the same orbit-disk system…

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astro-ph.SRastro-ph.HEphysics.space-ph2026年10月7日

Wave-Growth-Limited Particle Confinement in a Near-Parallel Interplanetary Shock Observed by Parker Solar Probe

A. Kouloumvakos, I. C. Jebaraj, M. A. Malkov, G. D. Berland, M. Gedalin, N. Wijsen, C. M. S. Cohen, O. V. Agapitov et al.

Collisionless shocks confine the particles they accelerate with the upstream wave field they themselves drive. Streaming particles resonantly amplify Alfvén waves, and the waves then confine the same particles by pitch-angle scattering. The rigidity a shock precursor can hold is therefore capped by how fast those waves grow, and that coupling has not previously been constrained in-situ at any interplanetary shock. Here we report Parker Solar Probe measurements of a fast, near-parallel coronal ma…

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astro-ph.HEgr-qcnucl-th2026年10月7日

Composition $g$-modes and $f$-modes of neutron stars with gravitationally coupled dark matter: degeneracy with the symmetry energy

Probit J Kalita, Bharat Kumar, H C Das

Composition gravity ($g$) modes have been proposed as a probe of dark matter in neutron stars, on the basis of one-fluid models in which the dark matter is in chemical equilibrium with the neutrons. We computed in full general relativity the $g$- and $f$-modes of stars in which fermionic dark matter couples to the nucleons only through gravity, and inferred the dark mass fraction from NICER and GW170817 data with a prior that comprises $63$ nucleonic equations of state (EOSs) from Skyrme and rel…

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astro-ph.SRastro-ph.GA2026年10月7日

On the origin of the short-period Blue Straggler Stars in Collinder 261: a binary evolution approach

M. Echeveste, M. J. Rain, G. Carraro, O. G. Benvenuto, J. A. Panei, M. A. De Vito

Building on the recent publication of a fresh catalog of blue straggler stars in Galactic open clusters using Gaia DR3, we conduct a study focusing on the blue straggler stars with short-period photometric variability found in the open cluster Collinder 261: nine eclipsing or ellipsoidal binaries and five SX Phe pulsator candidates. Our investigation delves into the potential of mass transfer in binary systems to account for the presence and properties of these stars. We first measure their phot…

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astro-ph.EPastro-ph.SR2026年10月7日

Astrometric planet search around southern ultracool dwarfs: V. Discovery of the exoplanet candidate PALTA-1 b

J. Sahlmann, P. F. Lazorenko, E. L. Martín, D. Ségransan, M. Mayor, S. Udry

We report the discovery of PALTA-1 b, a sub-Jupiter mass exoplanet candidate orbiting the nearby early-L dwarf DENIS-P J1253108-570924 (DE1253-57) located at a distance of ~17 pc. The exoplanet was discovered by monitoring the L dwarf's astrometric motion with FORS2 at the Very Large Telescope over more than eight years and characterising the deviations from the expected single-source motion. The estimated planet mass is between 0.54 MJup and 0.77 MJup, depending on the uncertain mass of the ult…

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astro-ph.EP2026年10月7日

The GAPS Programme at TNG. LXXX. Characterisation of the 400 Myr old multi-planet system K2-233

V. Fardella, S. Benatti, R. Spinelli, D. Locci, G. King, M. Baratella, K. Biazzo, S. Desidera et al.

Understanding exoplanet physical properties is crucial for characterising their atmospheres and internal composition. Precise planetary masses are essential for constraining bulk densities and interiors, particularly in young systems hosting planets within or near the radius valley, where atmospheric mass loss may strongly shape their evolution. Here we revise the masses of the three transiting planets orbiting K2-233, a young ($\sim 400$ Myr) active K-type star. We combine 70 HARPS-N observatio…

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astro-ph.SRphysics.flu-dynphysics.plasm-phphysics.space-ph2026年10月7日

The existence of null points of flow and magnetic fields as prerequisites for the presence of astropauses and their co-location

Dieter H. Nickeler, Kuljeet S. Saddal, Rodrigo Meneses Pacheco, Michaela Kraus

Astropauses can be defined via magnetic or fluid separatrices. For the boundary layer between the stellar wind and the local interstellar medium, two separatrices can occur, the magnetopause and the hydropause. The question is whether they are identical. To address this, we investigate under which conditions the null points of the magnetic and velocity field, which define the corresponding separatrices, coincide spatially. We analysed the case of a non-monotonous pressure distribution driving st…

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