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.SRastro-ph.GAastro-ph.HE

The Kick Velocities of Neutron Stars in Binary Systems

Paul Disberg, Ilya Mandel, Ryosuke Hirai

Neutron stars (NSs) receive natal kicks on their formation in supernovae (SNe). We consider constraints placed on the natal kick magnitudes by NSs in different classes of binary systems. We compare observed systems to predictions from the COMPAS rapid population synthesis code, where we apply kick models with varied natal kick prescriptions. Specifically, we compare binary orbits (i.e., periods and eccentricities) and systemic kick estimates of (1) Gaia observations of NS-harboring binaries (Gai…

詳細を見る →
astro-ph.GA

OutThere Survey: Addressing $\mathrm{ξ_{ion}}$ and $\mathrm{f_{esc}}$ with a population of average galaxies at z$\sim$2

Ravi Jaiswar, Anshu Gupta, Elisabete da Cunha, Cathryn M. Trott, Andrew Battisti, Isabel Perez, Karl Glazebrook, Lalitwadee Kawinwanichakij et al.

Constraining the major contributors to the ionisation of the early universe is an ongoing endeavour of high-redshift galaxy research. We measure the ionising photon production efficiency and Lyman Continuum escape fraction for a sample of 230 intermediate redshift ($1.3 $5. This control sample allows us to verify the correlations between ionising and spectral/physical properties suggested by previous studies. We find no significant correlations between the ionising photon production efficiency (…

詳細を見る →
astro-ph.IMastro-ph.CO

Towards independent event horizon imaging of the supermassive black holes in M87 and the Milky Way

Nithyanandan Thyagarajan, Samuel Lai, Ivy Wong, Foivos Diakogiannis

The Event Horizon Telescope (EHT) Collaboration's images of the supermassive black holes in M87 and the Milky Way have provided the first event-horizon-scale views of these objects, opening new avenues for studies of gravitation, accretion physics, and black hole astrophysics. Achieving these results, however, requires imaging under some of the most challenging conditions in radio astronomy, including low signal-to-noise ratios, severe calibration uncertainties, and sparse aperture coverage. Wit…

詳細を見る →
astro-ph.GAastro-ph.CO

Diversity of Ionized Gas Structures in Nearby Metal-poor Dwarf Galaxies

Yuki Takagishi, Takuya Hashimoto, Kazuya Matsubayashi, Matthew Hayes, Aida Wofford, Masato Hagimoto, Akio K. Inoue, Ken Mawatari et al.

We investigate whether optical and far-infrared [O III] emission from nearby metal-poor dwarf galaxies can be represented by a homogeneous one-zone ionized-gas model with a single electron temperature and density. Our sample comprises five galaxies from the Herschel Dwarf Galaxy Survey: HS1222+3741, SBS0335-052E, POX186, Haro11, and IZw18. We combine galaxy-integrated or nearly galaxy-integrated [O III] 4363 and 5007 measurements from Seimei/KOOLS-IFU observations and published or archival spect…

詳細を見る →
astro-ph.GA

The UKIRT M33 Monitoring Project: A 15-Year Near-Infrared Variable Star Catalogue for the Central Kiloparsec, and Prospects for Star Formation History and Dust Return

Mina Alizadeh, Fatemeh Nikzat, Atefeh Javadi, Yousefali Abedini, Jacco Th. van Loon, Hedieh Abdollahi

We present results from the UKIRT M33 Monitoring Project, a near-infrared survey of variable red giants in the Local Group spiral galaxy M33. Combining four independent photometric datasets spanning UIST (2003), UFTI (2005), WFCAM (2005-2007), and a new UKIRT Hemisphere Survey epoch (2018), we construct a homogenised 15.11-year $K$-band light-curve catalogue for 847 stars in the central kiloparsec, of which 771 (91 per cent) are variable. Cross-matching with archival Spitzer photometry identifie…

詳細を見る →
astro-ph.EPastro-ph.IM

Diffractive-Sail Single-Impulse Reachable Set for Interplanetary Transfer Design

Shuyue Fu, Jinkai Zhang, Di Wu, Peng Shi, Shengping Gong

Interest in planetary exploration has renewed, and the design of interplanetary transfers has attracted remarkable attention. This paper considers the interplanetary transfer design using a diffractive sail. Considering a nonzero departure hyperbolic excess velocity, the interplanetary transfer problem is transformed into the problem of computing single-impulse reachable sets. Then, based on previous work, a complementary computational method for reachable sets under arbitrary dynamics is propos…

詳細を見る →
physics.plasm-phastro-ph.HE

Revisiting the Growth Rate of the Relativistic Tearing Instability: The Role of the Non-ideal MHD Structure

Kaoru Sugimoto, Kunihito Ioka, Masaru Shibata

Magnetic reconnection in magnetically dominated pair plasmas is a key process in high-energy astrophysical systems. We revisit the relativistic tearing instability in a Harris current sheet and derive an improved analytical expression for its linear growth rate and the most unstable wavenumber. The key modification is the treatment of the vector potential perturbation in the non-ideal magnetohydrodynamic (MHD) region. Instead of the conventional constant-A approximation, we use an extrapolated-A…

詳細を見る →
physics.hist-phastro-ph.EP

The comets discovered from New Zealand, and the astronomers who found them

John Drummond, Wayne Orchiston, Carolyn Brown, Jonathan Horner

Eleven comets were discovered by six New Zealanders from New Zealand shores. New Zealand's important geographical position south of the Equator is highlighted. This location allows observers to discover and observe comets that would be difficult to see from the Northern Hemisphere. The lives of these comet discoverers are explored, as well as the discovery circumstances and an analysis of the morphological changes of their comets. We find that numerous New Zealand observers made many observation…

詳細を見る →
astro-ph.HE

First Observational Evidence for QPO-like Coevolution between Characteristic Damping Timescales and X-ray Time Lags among AGNs

Haoyang Zhang, Li Zhang

Quasi-periodic oscillations (QPOs) and stochastic variability provide complementary probes of the inner accretion flow around supermassive black holes in active galactic nuclei (AGNs). Previous multi-epoch studies of narrow-line Seyfert 1 galaxy RE~J1034+396 revealed a coevolution between the QPO frequency and the X-ray time lag, but whether the stochastic variability participates in the same structural evolution has remained unclear. We analyze the multi-epoch XMM-Newton observations of RE~J103…

詳細を見る →
physics.plasm-phastro-ph.HE

Characterizing the temporal evolution of Biermann-battery-driven magnetic reconnection in laser-ablated plasmas

T. Morita, Y. Muramoto, S. Isayama, M. Edamoto, M. Hanano, R. Ishikawa, Y. Kanesada, K. Koba et al.

This paper presents an experimental investigation of magnetic reconnection between two laser-produced expanding plasmas, focusing on the quantitative evaluation of the reconnection rate and energy conversion under varying initial conditions. By changing the separation distance between the drive laser focal spots (1 mm and 2 mm), we systematically controlled the inflow parameters. The reconnection region was probed using a two-directional laser Thomson scattering (LTS) system, which simultaneousl…

詳細を見る →
astro-ph.HEastro-ph.SRnucl-th

Discovery of Three Glitches in the previously quiet pulsar PSR J1637$-$4642

Zhaoyi Wang, Chuwen Zheng, Yuhong Zhuang, Hanyu Zhang, Peng Liu, Zhonghao Tu, Ang Li

We present the discovery and analysis of three rotational glitches in the young pulsar PSR J1637$-$4642. The timing observations span from 19 February 2009 to 6 October 2024 (MJD 54881$-$60589) from the Murriyang radio telescope of the Parkes Observatory. The first and strongest glitch occurred around MJD 58352 with a fractional frequency change of $Δν/ν\sim 2.7 \times 10^{-6}$, while two additional smaller glitches were detected at MJD 59443 and MJD 60445 with fractional changes of $2.2 \times…

詳細を見る →
astro-ph.GA

The VariableTNG project: mass-dependent regulation of galaxy morphology by baryonic feedback

Yikai Liu, Hong Guo, Volker Springel, Kexin Liu, Luis C. Ho, BoCheng Zhu

Galaxy morphology is shaped by both assembly history and baryonic processes, but their relative roles remain uncertain. We use the VariableTNG (VTNG) simulation suite to investigate how variations in baryonic feedback regulate galaxy morphology while keeping the initial conditions fixed. VTNG consists of cosmological magnetohydrodynamic simulations performed with the moving-mesh code {\sc AREPO}, varying eight parameters governing stellar and AGN feedback. At $z=1$, we characterize morphology us…

詳細を見る →
astro-ph.SRastro-ph.GA

Non-ideal MHD and protostellar feedback effects on disc formation and evolution in numerical simulations of star cluster formation

Nina Filippova, Stella S. R. Offner, Michael Y. Grudic, Philip F. Hopkins

While recent surveys have resolved hundreds of nearby protostellar discs, numerical simulations assuming ideal magnetohydrodynamics (MHD) have historically struggled to achieve disc formation due to efficient angular momentum removal by magnetic torques. Non-ideal MHD effects, relevant at the low ionization fractions typical of molecular clouds, have been shown to reduce the effectiveness of magnetic braking and promote disc formation. In this work, we present the results from a suite of calcula…

詳細を見る →
astro-ph.HE

Outflows in steep density gradients: diversity of behavior and implications for tidal disruption events and luminous fast blue optical transients

Benjamin Amend, Michael Camilo, Eric R. Coughlin, Anna Y. Q. Ho, Jonathan Zrake

Powerful explosions may undergo sustained energy injection as a central engine launches a wind into the surrounding gas, generating a forward and a reverse shock separated by a contact discontinuity. During the adiabatic phase, the dynamics depend strongly on the wind-to-ambient density ratio $f \equiv ρ_{\rm w} / ρ_{\rm a}$. For $f 2$, initially underdense outflows produce accelerating forward shocks whose radii evolve as $R_{\rm s} \propto t^{3/(5-n)}$. Because $ρ_{\rm w} \propto r^{-2}$, f in…

詳細を見る →
astro-ph.SRastro-ph.GA

A Systematic Gaia--ZTF Search for Short-Period Blue Compact-Binary Candidates

Jiamao Lin, Liangliang Ren, Yilong Li, Bo Ma, Di-Chang Chen, Zi-Heng Yu, Sen Yang, Shun-Jia Huang et al.

We present a catalog of 147 short-period (10.34--106.46~min) blue compact-binary candidates, identified by combining Gaia DR3 astrometry and photometry with ZTF DR23 light curves via a Gaia selection, period searches, and machine-learning morphology ranking. Of these, 111 lack prior compact-binary classifications. Multiwavelength data (DESI DR1, GALEX, AllWISE) reveal a heterogeneous sample: on the Gaia colour--magnitude diagram, 52 sources lie on the white-dwarf locus, 69 in the hot-subdwarf re…

詳細を見る →
astro-ph.SR

Correlations with Magnetic Activity in the Solar Near-Surface Shear Layer. II. Radial Shear

M. Cristina Rabello Soares, Sarbani Basu, Richard S. Bogart, Charles S. Baldner

Using Helioseismic and Magnetic Imager ring-diagram measurements and building on the rotation-rate $Ω$ inferences presented in Paper I for depths of 1-17 Mm, we examine the properties of the dimensionless radial shear $\partial\lnΩ/\partial\ln r$. In the radial range overlapping global-mode analyses, the inferred shear agrees with previous results. The near-surface shear layer exhibits a three-region shear structure with an enhanced-shear middle layer, and the largest residual variations occur i…

詳細を見る →
astro-ph.IM

Fast Control for LIGO Interferometer Lock Acquisition

Masaya Ono, Nathan A. Holand, Radhika Bhatt, Peter G. Carney, Francisco Salces Càrcoba, Koji Arai, Rana X. Adhikari

Gravitational wave observatories are large scale laser interferometers which are held on resonance to facilitate the detection of gravitational waves. Achieving this resonant condition is a time consuming process, and in the LIGO gravitational-wave observatories this procedure has a relatively low success rate. This limitation leads to a loss of observation time thereby reducing the number of observable astrophysical events. The primary cause of this problem is the coupling among the longitudina…

詳細を見る →
astro-ph.EPastro-ph.IM

Finding Habitable Exoplanets with Binary Relative Astrometry: Planet Detection and Characterization with the Microarcsecond Astrometric Retrieval Algorithm (MARA)

William Roberson, Eric L. Nielsen, Jessie L. Christiansen, Gautam Vasisht, Eduardo Bendek, Alex Davis, Eric E. Mamajek, Catherine A. Clark et al.

Binary relative astrometry is a technique to search for rocky planets in the habitable zone of nearby binary stars using 1D relative astrometry at the microarcsecond level. This unprecedented precision would allow a custom-designed space telescope to directly measure the occurrence rate of these planets. The success of such a mission depends on our ability to recover and characterize planets from the unique format of extreme precision binary relative astrometry data. We present MARA, the Microar…

詳細を見る →
astro-ph.GA

Tracing Lyman alpha escape in the CRISTAL-02 galaxy at z~5.3

Arshi Ali, Lucia Guaita, Manuel Aravena, Rebecca L. Davies, Jorge Gonzalez, Vicente Villanueva, Diego Oyarzun, Rodrigo Herrera-Camus et al.

Aim. We investigate the mechanisms regulating Lyman-alpha (Ly-a) escape in the star-forming galaxy CRISTAL-02 at z~5.3. The galaxy hosts five distinct clumps, with Clumps A and B suggested as potential active galactic nuclei (AGN) candidates. We study how AGN or star formation activity influences the spatial distribution and escape of Ly-a emission. Methods. Using VLT/MUSE Ly-a and JWST/NIRSpec IFU H-a and H-b observations, complemented by NIRCam UV imaging, we constructed spatially matched emis…

詳細を見る →
astro-ph.GA

Tracing Lyman alpha escape in the CRISTAL-02 galaxy at z~5.3

Arshi Ali, Lucia Guaita, Manuel Aravena, Rebecca L. Davies, Jorge Gonzalez, Vicente Villanueva, Diego Oyarzun, Rodrigo Herrera-Camus et al.

We investigate the mechanisms regulating Lyman-alpha (Ly$α$) escape in the star-forming galaxy CRISTAL-02 at z~5.3. The galaxy has clumpy morphology, suggestive that it may be interacting with other system(s). Two clumps (A and B, hereafter) are suggested as a site for intense star-formation or potential AGN candidates. We investigate how the local gas, dust, and feedback shape the escape of Ly$α$ photons around these clumps. Using VLT/MUSE and JWST/NIRSpec IFU observations, complemented by NIRC…

詳細を見る →
astro-ph.SR

Correlations with Magnetic Activity in the Solar Near-Surface Shear Layer. I. Rotation

M. Cristina Rabello Soares, Sarbani Basu, Richard S. Bogart

We used data from the Helioseismic and Magnetic Imager to determine the rotation rate of the near-surface shear layer and its time variation. We applied the ring-diagram analysis technique allowing us to probe the layer between the depths of 1 Mm and 17 Mm. We find that the rotation rate increases inwards; it reaches values consistent with those inferred from global helioseismic analyses in the deeper layers, however, there are differences in the rotation rate of the northern and southern hemisp…

詳細を見る →
astro-ph.GA

Reconstructing orbits of galaxies in extreme regions (roger v2.0): an extension to intermediate mass systems

Martín de los Rios, Héctor J. Martínez, Andrés N. Ruiz, Selene Levis, Valeria Coenda, Hernán Muriel

In this paper, we present an updated version of the roger code, called roger v2.0, developed to perform the orbital classification of galaxies residing in and around galaxy groups and clusters. In addition to the projected phase-space coordinates, the new version incorporates the host halo mass as an additional input parameter. Although the inclusion of the halo mass leads to only modest changes in the classification, it contributes to improving the overall robustness of the method. We also exte…

詳細を見る →
astro-ph.SRastro-ph.IM

Responses of the X-ray spectrometer/imager STIX onboard Solar Orbiter

Hualin Xiao, Olivier Limousin, Ewan Dickson, Säm Krucker

Solar flares are explosive events that release X-rays from hot plasma and accelerated electrons. The STIX instrument on the Solar Orbiter provides imaging spectroscopy of solar X-ray emissions from 4 to 150 keV. To interpret the STIX data accurately, understanding the instrument's response is crucial. Given the complexity of interactions of X-rays with the instrument, we developed a detailed Monte Carlo model for STIX based on Geant4. The model accurately depicts the instrument's components, suc…

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

Microlensify: a Transformer Based Machine Learning Classifier for Microlensing Events Trained on TESS Light Curves

Atousa Kalantari, Somayeh Khakpash, Sedighe Sajadian, Hosein Haghi, Willow Fox Fortino, Rosanne Di Stefano

Microlensing can reveal populations of faint compact objects that are otherwise difficult to detect. Depending on their design, all-sky surveys have the potential to search for these objects across the sky. The Transiting Exoplanet Survey Satellite (TESS), primarily designed to detect transiting exoplanets, also provides near all-sky coverage with high cadence. In this work, we use TESS data to search for microlensing candidates using both traditional and machine-learning methods and to identify…

詳細を見る →
astro-ph.IM

ADORA: a differentiable optical modeling and astrometric retrieval framework for SHERA

Dylan McKeithen, Stuart Shaklan, Gautam Vasisht, Joe Green, Rhonda Morgan, Louis Desdoigts, Peter Tuthill

Searching for Habitable Exoplanets with Relative Astrometry (SHERA) is a proposed Small Explorer mission concept designed to measure the separation of nearby binary stars at microarcsecond-class precision. Recovering this signal requires separating astrophysical motion from coupled changes in pointing, plate scale, wavefront error, spectral response, and detector calibration. We present the Astrometric Differentiable Optics and Retrieval Algorithm (ADORA), an image-domain framework that combines…

詳細を見る →
astro-ph.HEastro-ph.GAastro-ph.SRgr-qc

Modeling Relativistic Tidal Disruptions of MESA Stars

Liam M. Wang, Giovanni Maria Tomaselli, Zihan Zhou

Tidal disruption events (TDEs) occur when a star passes so close to a black hole that its self-gravity is overcome by the external tidal field. As the star passes, it initially deforms, then is ripped apart, and some of its material eventually falls back on bound orbits, forming an accretion disk around the black hole. A Newtonian model of TDEs, based on stellar perturbation theory of MESA stars, was recently introduced as an alternative to computationally intensive hydrodynamical simulations. I…

詳細を見る →
physics.plasm-phastro-ph.HE

Informing spectral models for dense plasmas with K-edge absorption measurements of warm dense copper

T. Cordova, E. V. Marley, D. A. Chin, R. A. London, S. B. Hansen, S. M. Vinko, J. E. Pask, H. A. Scott et al.

Warm dense matter remains a challenging regime to characterize experimentally and to model with predictive accuracy. Recent experimental platforms have been developed to generate, characterize, and diagnose uniform warm dense matter, enabling detailed comparisons with models. Here, we present experiments conducted at the OMEGA laser facility that compress and heat a buried layer target to warm dense matter conditions, where the targets are heated to temperatures of approximately 20 eV and compre…

詳細を見る →
astro-ph.IMastro-ph.EP

Shaping SHAPE - A spectro-polarimeter onboard Chandrayaan-3 to observe Earth as an Exoplanet

Anuj Nandi, Swapnil Singh, Bhavesh Jaiswal, Anand Jain, Smrati Verma, Reenu Palawat, Ravishankar B. T., Brajpal Singh et al.

Spectro-polarimetry of HAbitable Planet Earth (SHAPE) is an experimental instrument onboard the Propulsion Module (Orbiter) of the Chandrayaan-3 mission, designed to perform disc-integrated spectro-polarimetric observations of Earth from lunar and highly elliptical Earth orbits. SHAPE is a compact, lightweight spectro-polarimeter comprising three subsystems: the Electro-Optical Detector System (EODS)-Optics, EODS-Electronics, and Radio Frequency Source (RFS). An Acousto-Optic Tunable Filter (AOT…

詳細を見る →
astro-ph.SRastro-ph.EPastro-ph.GA

Early Planet Formation in Embedded Disks (eDisk). XXIV: Systematic Investigation of Disk Structures based on Visibility Analysis

Mayank Narang, Jerry Xu, Leslie W. Looney, Nagayoshi Ohashi, Anika Khandavalli, Patrick Sheehan, Jonathan P. Williams, Shigehisa Takakuwa et al.

The dust continuum emission from young protostellar disks encodes key information about their mass distribution and early evolution, yet uniform high-resolution comparative studies remain limited. We present a systematic uv-plane analysis of parametric intensity models applied to ALMA Band-6 (1.3 mm) observations of 23 disks (19 protostellar systems with 4 being in binary) from the eDisk sample, spanning Gaussian profiles to power-law cores with exponential tails (PLCT), including asymmetric ext…

詳細を見る →
astro-ph.SR

ALMA high resolution observations of Betelgeuse: Persistent structure spanning the inner atmosphere

W. R. F. Dent, A. M. S. Richards, G. M. Harper, L. D. Matthews, E. O'Gorman

The extended atmosphere of red supergiants (RSGs) forms an important link in the process of mass loss and the subsequent enrichment of the interstellar medium. Large-scale convection is thought to play a significant role, which is likely to result in irregularities in the surface. High resolution, high contrast sub-mm images of Betelgeuse - one of the closest RSGs - are used to probe the structure and temporal stability of the inner 1-2$R_\star$ of its atmosphere. Using ALMA in the longest basel…

詳細を見る →