UchUchU

研究動向

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.GA

Comprehensive X-ray Study of Giant Radio Galaxies with XMM-Newton and Chandra

Niraj Maurya, Satish S. Sonkamble, Suraj Dhiwar, M. B. Pandge, S. Ilani Loubser, Avinash Kale

We present a systematic X-ray spectral analysis of 27 giant radio galaxies (GRGs) using archival \textit{XMM-Newton} and \textit{Chandra} data. Roughly 44\% of the sample show intrinsic absorption ($N_{\mathrm{H,int}} \gtrsim 10^{21}\,\mathrm{cm}^{-2}$), while several exhibit narrow Fe K$α$ emission lines with equivalent widths up to $\sim$570 eV. Soft X-ray features are also common, including thermal plasma emission (kT$\sim 0.2$--0.8 keV) and ionized absorbers, in some cases consistent with hi…

詳細を見る →
astro-ph.IM

PhySR: Physics-Informed Neural Network for Super-Resolution Reconstruction in Radio Synthesis Imaging

Hongkun Yang, Li Zhang, Ming Zhang, Yong-Feng Huang

Radio telescope arrays are constrained by the number of antennas and baseline distribution, resulting in incomplete spatial-frequency sampling, limited image resolution, and blurring, distortion, and loss of small-scale structures caused by coupling between the primary and synthesized beams. Existing general-purpose model-driven methods remove observational effects sequentially and may accumulate errors, but cannot directly address limited imaging resolution, while data-driven methods lack expli…

詳細を見る →
astro-ph.HE

eRASSU J043115.8-711730: The first pulsating symbiotic super-soft X-ray source in the Magellanic Bridge

Tathagata Saha, Chandreyee Maitra, Philip Charles, Frank Haberl, David Kaltenbrunner, Andrej Udalski, David Buckley, Itumenleng Monageng et al.

The Magellanic Bridge stellar population is a relic of the tidal interaction between the Large and Small Magellanic Clouds. A comprehensive view of the evolution of the Bridge stellar population requires probing the compact remnants of stellar evolution, otherwise hidden at optical wavelengths. The all-sky survey conducted by the eROSITA instrument on-board the Spectrum Roentgen Gamma observatory has discovered a significant population of compact-object-powered systems in the Bridge using X-ray.…

詳細を見る →
astro-ph.HE

Distinct Jet Properties in the X-Ray-Obscured State of GRS 1915+105

Xi Yan, Lang Cui, Sergei Trushkin, Shuangjing Xu, Wu Jiang, Zhen Yan, Sándor Frey, Timur Mufakharov et al.

GRS 1915+105 has remained in an X-ray-obscured state since its transition from a long-lasting unobscured state in 2019. We report on 6.7-GHz East Asia VLBI Network observations of GRS 1915+105 obtained during strong radio flares detected at 2.3--11.2 GHz with the RATAN-600 radio telescope in 2025. Our images reveal two contrasting jet morphologies. The first epoch, associated with a flare evolving from an optically thick to an optically thin spectrum, shows a bright radio core accompanied by an…

詳細を見る →
astro-ph.GA

The X-ray-Weak Tail of the Quasar Population: Physical Properties and Redshift Evolution of Variability-Selected AGN in eFEDS

P. Arévalo, J. Buchner, M. Salvato, P. Sánchez-Sáez, F. Bauer, M. L. Martínez-Aldama, D. Tubín-Arenas, J. Cerón-Meneses et al.

(abridged) Aims: To characterize variability-selected AGN candidates within the eROSITA Final Equatorial-Depth Survey (eFEDS), leveraging the synergy between optical variability and deep X-ray observations by SRG (Spectrum Roentgen Gamma)/eROSITA, to compare the physical properties of AGN populations selected through complementary methods. Methods: We used a sample of AGN candidates selected via optical variability by Arévalo et al. and cross-match it to the X-ray selected eFEDS AGN sample. Spec…

詳細を見る →
astro-ph.IM

Proof of Concept Measurements of Laterally Graded Multilayers for Soft X-ray Spectropolarimetry

Sarah Heine, Herman L. Marshall, Alan Garner, Eric Gulllikson, Nithya Kothnur

This work describes proof of concept measurements for a soft X-ray spectropolarimeter that utilizes laterally graded multilayer mirrors within a grating spectrometer. The work tests two multilayers: a Chromium-Scandium multilayer designed to be utilized at Brewster's angle in the 200-400 eV range and a Tungsten Boron Carbide mirror designed to reflect X-rays at 30 degrees incidence in the 500-850 eV range. We present measurements of monochromatic, polarized light reflecting off of these multilay…

詳細を見る →
astro-ph.GA

Galactic HII regions in LAMOST Medium-Resolution Spectroscopic Survey of Nebulae

Yunning Zhao, Wei Zhang, Lin Ma, Shiming Wen, Tao Jing, Cheng Li, Zheng Zheng, Aiyuan Yang et al.

Based on LAMOST Medium-Resolution Spectroscopic Survey of Nebulae (MRS-N) data and WISE Galactic HII region catalog, we construct a sample of 280 Galactic HII regions and candidates in the Outer Galaxy (80$^{\circ}$ $\lesssim$ l $\lesssim$ 220$^{\circ}$). Using MRS-N optical spectra, we measure four emission lines (H$α$, [NII]$λ$6584, [SII]$λλ$6717,6731) and use line-ratios to spectroscopically confirm 255 HII regions, including 90 previously "Known" HII regions and 165 newly classified ones. We…

詳細を見る →
astro-ph.HE

On the Blueprint of Active Galaxies Producing Neutrinos

Chen Li, Francis Halzen

Based on the observation of the active galaxies NGC 1068 and TXS 0506+056, and on additional evidence for the sources NGC 4151, CGCG 420-015, NGC 7469, and the Circinus Galaxy emerging from IceCube data, we make the case for the production of high-energy neutrinos within a few gravitational radii of supermassive black holes surrounded by a dense plasma radiating X-rays. X-rays represents the target for the production of neutrinos by protons accelerated near the black hole; they also absorb the g…

詳細を見る →
astro-ph.HE

An extra hard spectral component peaking at sub-GeV in the prompt emission of GRB 260226A

Yi-Yun Huang, Hai-Ming Zhang, Ruo-Yu Liu, Xiang-Yu Wang

The prompt emission spectra of gamma-ray bursts (GRBs) have long been empirically described by the Band function over the keV--MeV range, whereas several \textit{Fermi}/LAT-detected GRBs show evidence for an extra hard component at higher energies. Here we present a joint GBM--LAT study of GRB~260226A, a rare LAT seeded onboard trigger GRB, and find that an extra sub-GeV component is present. In the time-resolved analysis, we find that a cutoff power-law model fits the spectral data of the extra…

詳細を見る →
astro-ph.IM

Design and testing progress towards the first flight of the rocket experiment demonstration of a Soft X-ray Polarimeter (REDSoX)

Sarah N. T. Heine, Herman L. Marshall, Alan Garner, F. Elio Angile, C. Marc Baker, Stephen Bongiorno, Leonardo Drake, H. Moritz Gunther et al.

The Rocket Experiment Demonstration of a Soft X-ray Polarimeter (REDSoX) is a NASA-funded, sounding rocket mission. The rocket payload will measure polarization strength and direction as a function of energy in the 0.2-0.4 keV band, providing complementary measurements to those made by IXPE in the 2-8 keV band. The first flight, scheduled for 2028, will provide a technology demonstration of our polarimeter concept, which utilizes an aligned system of a focusing optic, Critical-Angle Transmission…

詳細を見る →
astro-ph.HE

Depolarization Induced by Rapid Polarization Angle Swings: A Common Feature of Pulsars and Fast Radio Bursts?

Yu-Chen Huang, Jie-Shuang Wang, Song-Bo Zhang, Zi-Gao Dai

The polarization angle (PA) of pulsars and fast radio bursts (FRBs) provides a useful diagnostic of the magnetic fields in their emission regions and is therefore crucial for understanding their radiation and origins. Within a general geometric framework for polarized emission from a rotating neutron star, we suggest a possible anti-correlation between the degree of linear polarization $Π_\text{L}$ and $d\text{PA}/dt$, the time derivative of the PA, as a common feature of pulsars and FRBs. The d…

詳細を見る →
astro-ph.EP

Rotation and Mutual Eclipse Events Season in the Kuiper Belt: (524366) 2001 XR$_{254}$

Audrey Thirouin, William M. Grundy, Scott S. Sheppard, Keith S. Noll, José María Gómez-Limón, Benjamin Proudfoot

(524366) 2001 XR$_{254}$ is a dynamically Cold Classical Kuiper Belt Object that is a nearly equal-sized wide binary whose upcoming mutual events season makes it a particularly valuable target for physical characterization. In advance of the mutual eclipse events, we conducted a ground-based photometric observing campaign between 2021 and 2026 using the \textit{Lowell Discovery Telescope} to investigate the rotational and physical properties of the system, to refine predictions for its future mu…

詳細を見る →
gr-qcastro-ph.HEhep-th

Tidal Love numbers of multi-state Boson stars

Xin-Lei Zhao, Jun-Ru Chen, Yong-Qiang Wang

In this paper, we calculate the tidal Love numbers of multi-state boson stars (MSBSs) composed of ground state and first excited state complex scalar fields. Under synchronized and nonsynchronized frequency conditions, the background solutions of MSBSs are classified into single-branch and double-branch types. The field functions, ADM mass, and binding energy of different solutions are discussed. We then calculate the quadrupolar ($\ell=2$) electric and magnetic tidal Love numbers for branches c…

詳細を見る →
astro-ph.EP

Setting the Stage: The Early History of the Solar System

Antgona Segura, Rachel L. Smith, Myriam Telus, Edward Schwieterman, Rachel Osten, Sukrit Ranjan

This article reviews the early history of our solar system from an astrobiological perspective and presents evidence from meteorites and astronomical observations. The purpose is to trace the formation of key molecules that participated in the building blocks of life. The Sun and its planetary system started from a section of a molecular cloud that collapsed into a protoplanetary disk. In the center of the protoplanetary disk, the protosun heated the surrounding material. The dust and gas inheri…

詳細を見る →
astro-ph.EPastro-ph.SR

Stellar Activity, Exoplanet, Habitability, Planetary Atmospheres

Antígona Segura, Manuel Güdel, Konstantin Herbst, Dibyendu Nandy, Arghyadeep Paul, Raissa Estrela, Allison Youngblood

This chapter will review the deep connection of planetary habitability and stellar irradiation. We present the long-term stellar evolution as one of the drivers of atmospheric escape and climate changes on exoplanets, as well as the chemistry driven by stellar UV and stellar energetic particles. Habitability is presented in the context of short and long-term stellar variability and evolution to layout what we understand and what we need to know about stellar irradiation to constrain our planetar…

詳細を見る →
astro-ph.EPastro-ph.SR

Stellar impact on exoplanetary atmospheric evolution and habitability

Antígona Segura, Manuel Güdel, Konstantin Herbst, Dibyendu Nandy, Arghyadeep Paul, Raissa Estrela, Allison Youngblood

This chapter will review the deep connection of planetary habitability and stellar irradiation. We present the long-term stellar evolution as one of the drivers of atmospheric escape and climate changes on exoplanets, as well as the chemistry driven by stellar UV and stellar energetic particles. Habitability is presented in the context of short and long-term stellar variability and evolution to layout what we understand and what we need to know about stellar irradiation to constrain our planetar…

詳細を見る →
gr-qcastro-ph.HEhep-th

Structural morphology and the gravitational arrow of time

Julian Barbour, Francisco S. N. Lobo, Maria I. R. Lourenço

The Newtonian $N$-body problem in the zero-energy, zero-linear-momentum, and zero-angular-momentum sector provides a time-reversal-invariant setting in which generic complete solutions possess a Janus point and exhibit a gravitational arrow on both branches away from it. The dimensionless variety $V$, a global scale-invariant measure of clustering contrast, is not pointwise monotonic but fluctuates while growing between rising bounds away from the Janus region. Central configurations are critica…

詳細を見る →
astro-ph.EP

Neptune's Inner Moons and Rings Are Exposed Icy Body Interiors

M. Ryleigh Davis, Matthew Belyakov, Ian Wong, Zachariah Milby, Michael E. Brown

Neptune's single large moon, Triton, is accompanied by a set of dusty rings and small moons whose composition and origin are uncertain. Using the James Webb Space Telescope, we observed Neptune's rings and three moons: Larissa, Galatea, and Proteus. Remarkably, these moons and rings have spectra that are distinct from other outer solar system objects and show no evidence of water ice, despite hosting deep 3 micron OH absorption bands. Additionally, Larissa, Galatea, and the rings show a composit…

詳細を見る →
astro-ph.HE

JWST Spectra Indicate a Large Mass of Postshock Dust Formed by SN 2010jl

Nathan Smith, Melissa Shahbandeh, Ori D. Fox, Thomas Moore, Jennifer E. Andrews, Thomas G. Brink, Eli Dwek, Michael Engesser et al.

We present new JWST mid-IR spectra and ground-based optical spectra of the lingering source at the position of SN 2010jl, which was a relatively nearby superluminous Type IIn supernova having strong interaction with circumstellar material (CSM). Early-time data showed evidence of dust, interpreted as either pre-existing CSM dust, or as newly formed dust in the SN ejecta and post-shock region. At 13 yr post explosion, JWST reveals a strong MIR excess from warm dust, with broad features at 10-15 $…

詳細を見る →
astro-ph.GA

Stellar photoionisation modelling in SYNTHESIZER

Aswin P. Vijayan, Stephen M. Wilkins, Sophie L. Newman, Christopher C. Lovell, William J. Roper, Sabrina Berger, Thomas Harvey, Jack C. Turner et al.

Emission from photoionised gas surrounding young stellar populations ($H\text{II}$ regions) provides critical diagnostics of the physical conditions in star forming galaxies. This emission constrains the gas properties, the nature of ionising sources, and generates essential features for determining galaxy redshifts. To leverage spectroscopic observations to test galaxy formation models, it is essential to incorporate these emissions into synthetic datasets. Here, we present the integration of p…

詳細を見る →
astro-ph.HEgr-qc

On the triple nature of the PSR J0435+3233 system

Paulo C. C. Freire, Colin J. Clark, Cees G. Bassa, Guillaume Voisin, Rutger van Haasteren, Lars Nieder, Benjamin W. Stappers

Context. The recent pulsar timing ephemeris of PSR J0435+3233 indicates that this millisecond pulsar (MSP) has a spin-down rate that is much higher than observed in other MSPs and challenges our understanding of the formation and evolution of MSPs. Aims. We propose that this system is a hierarchical triple, and that the high spin-down rate is caused by varying acceleration due to a tertiary in a wide orbit. Methods. We use pulsar timing methods with radio and gamma-ray observations of PSR J0435+…

詳細を見る →
astro-ph.IMastro-ph.SRphysics.space-ph

Compton Polarimeter Prototype for the CUbesat Solar Polarimeter (CUSP) mission

Nicolas De Angelis, Andrea Alimenti, Riccardo Campana, Mauro Centrone, Giovanni De Cesare, Ettore Del Monte, Sergio Di Cosimo, Enrico Costa et al.

The space-based CUbesat Solar Polarimeter (CUSP) mission aims to measure the linear polarization of solar flares in the hard X-ray band (25-100 keV) by means of a dual-phase Compton polarimeter. CUSP will allow to study the magnetic reconnection and particle acceleration in the flaring magnetic structures of our star with its unprecedented sensitivity to solar flare polarization. CUSP is a project under development as part of the Alcor Program of the Italian Space Agency aimed at developing new…

詳細を見る →
astro-ph.IMphysics.optics

Testing of machine learning wavefront sensing algorithms on the Tiny Observatory for Telescope Optimization (TOTO) testbed

Sanchit Sabhlok, Solvay A. Blomquist, Maggie Y, Kautz, Debstuti Biswas, Kevin Derby, Jaren N. Ashcraft, Hyukmo Kang et al.

Phase retrieval techniques are utilized to correct low order wavefront aberrations originating from misalignments of the optical system in space based telescope concepts. Traditional phase retrieval involves observation of the Point Spread Function (PSF) and a diversity measurement, usually focus diversity although other measures are possible, to reconstruct the incident wavefront at the science detector. We consider a Machine Learning model trained originally on simulated data, and then augment…

詳細を見る →
astro-ph.IM

Tiny Observatory for Telescope Optimization (TOTO): testing algorithms for autonomous on-orbit alignment for space-based telescope systems

Solvay A. Blomquist, Sanchit Sabhlok, Hyukmo Kang, Maggie Y. Kautz, Simran Agarwal, Heejoo Choi, Alexandra Kupersmith, Adam Schilperoort et al.

The Tiny Observatory for Telescope Optimization (TOTO) is an optical testbed designed to evaluate the efficacy of autonomously driven alignment algorithms for space-based telescope systems. For space-based missions, active control of the telescope alignment on-orbit offers potential to relax passive alignment requirements and reduce on-ground verification activities. TOTO is used to evaluate and verify simulation work of two primary alignment algorithms, Stochastic Parallel Gradient Descent (SPG…

詳細を見る →
astro-ph.HEastro-ph.IM

Radio Follow-Up of Einstein Probe Fast X-Ray Transients

Carmen Choza, Joe S. Bright, Francesco Carotenuto, Alex Pollak, Rob Fender, Andrew Siemion

Fast X-ray transients (FXTs) are brief, luminous bursts of soft X-ray emission whose physical origins remain uncertain. The Einstein Probe (EP) mission has recently enabled prompt discovery of these events, providing opportunities for rapid multi-wavelength follow-up. We present a coordinated radio observing campaign targeting 20 FXTs detected by the EP in 2024. The core consists of 59 epochs with the Allen Telescope Array (ATA), sampling post-burst timescales from $\sim$1 to $\sim$65 days and r…

詳細を見る →
astro-ph.IMastro-ph.EPastro-ph.GAastro-ph.SR

PhoPS: An automated photometric pipeline for survey-era astronomy

Orhan Erece, Yucel Kilic

Modern astronomical surveys produce large volumes of imaging data together with highly accurate astrometric and photometric reference catalogues, creating a need for automated, robust, and instrument-independent reduction pipelines. We present PhoPS (Photometry and Astrometry of Point Sources), an open-source Python pipeline for fully automated astrometric calibration and photometric reduction of stellar and moving Solar System targets. PhoPS dynamically generates local Gaia DR3 astrometric inde…

詳細を見る →
astro-ph.HE

Binary neutron star populations across cosmic time: the impact of binary stellar evolution uncertainties

Mathieu Venet, Irina Dvorkin

We investigate the impact of uncertainties in binary stellar evolution on the formation efficiency and cosmological merger rate of BNS systems. In particular, we aim to determine whether robust signatures of binary evolution can be identified across a broad range of metallicities. We perform a systematic exploration of 72 binary evolution models using the population synthesis code COSMIC. We vary four key parameters controlling the onset and efficiency of common-envelope evolution, the natal kic…

詳細を見る →
astro-ph.GAastro-ph.HE

Cosmic Pairs: A DESI Census of Dual and Offset AGN as Precursors to Massive Black Hole Binaries

Ekaterine Dadiani, Antonella Palmese, Yihao Zhou, Nianyi Chen, Tiziana Di Matteo, Alejandro Eróstegui, Mar Mezcua, Jessica Nicole Aguilar et al.

We present a systematic census of dual and offset active galactic nuclei (AGN) using spectroscopic data from the first data release (DR1) of the Dark Energy Spectroscopic Instrument (DESI). After correcting for observational systematics, our final sample contains $>7,000$ dual AGN and 27,000 galaxy pairs containing one AGN over the redshift range $0 \lesssim z \lesssim 3.6$. This sample expands the known dual AGN sample by $\sim 1-2$ orders of magnitude at $0.2 \lesssim z \lesssim 0.4$, includes…

詳細を見る →
astro-ph.GA

Exploring the Limits of Spectral Line Stacking in Spectral Line Data and Application Toward the Detection of Bulk $^{13}$C Enrichment of Aromatics in TMC-1

Miya Duffy, Ryan A. Loomis, Martin S. Holdren, Andrew Lipnicky, D. Archie Stewart, Gabi Wenzel, Ci Xue, Annapoorani Hariharan et al.

The formation history of polycyclic aromatic hydrocarbons (PAHs) in the interstellar medium remains a topic of active debate, with proposed mechanisms ranging from high-temperature stellar ejecta processes to low-temperature chemistry within molecular clouds. Recently, the identification of small PAHs in the cold, dark cloud TMC-1 has provided some circumstantial evidence of the latter. If these are formed in situ, their isotopic ratios, particularly $^{12}$C/$^{13}$C, should reflect the local,…

詳細を見る →
astro-ph.EP

High-Resolution Dayside Spectroscopy of the Ultra-Hot Jupiter WASP-178b with GHOST/Gemini South

Caitlin E. Bell, Emily K. Deibert, Adam B. Langeveld, Ernst de Mooij, Ray Jayawardhana, Laura Flagg, Jake D. Turner

We present high-resolution dayside spectroscopy of the ultra-hot Jupiter WASP-178b obtained with the Gemini High-resolution Optical SpecTrograph (GHOST) at the Gemini South Observatory. The observations cover pre- and post-eclipse orbital phases, lasting approximately 9 hours in total, and represent the first published high-resolution optical dayside emission spectroscopy of WASP-178b's atmosphere, complementing previous near-infrared dayside spectroscopy. We verify the presence of a thermal inv…

詳細を見る →