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.HE

Synchrotron-Regulated Relativistic Magnetohydrodynamic Turbulence: Emission, Polarization, and Faraday Rotation

Xiaochen Sun, Luca Comisso, Lorenzo Sironi, Anatoly Spitkovsky, Alexander Philippov

Relativistic magnetized plasmas in many high-energy astrophysical systems are both turbulent and strongly radiative, yet their nonlinear dynamics and radiative outcomes remain poorly understood. Here we present results from three-dimensional driven turbulence simulations in relativistic magnetohydrodynamics with synchrotron cooling. We compute Faraday rotation measures, synthetic synchrotron spectra and linear polarization maps from the simulated turbulence. The balance between energy injection…

詳細を見る →
astro-ph.SR

Exploring the long-term temporal variability in polarization through multi-epoch optical spectro-polarimetry - Part I: A sample of Herbig Ae/Be and classical Be stars

Arijit Maiti, Mudit K. Srivastava

Polarization signatures across emission line features, together with their temporal evolution, offer a powerful probe of the circumstellar environments of astrophysical sources, on spatial scales otherwise inaccessible to direct imaging techniques. However, the photon-hungry nature of spectro-polarimetry has significantly limited the availability of such datasets in the literature. This work reports a multi-epoch spectro-polarimetric monitoring campaign targeting a sample of Herbig Ae/Be and cla…

詳細を見る →
astro-ph.IMgr-qchep-ph

Full-Covariance Bayesian Inference of Stochastic Gravitational Wave Background with Time-Domain Simulations for Taiji-like Missions

Qingyuan Liang, Ju Chen, Minghui Du, Huai-Ke Guo

For Taiji-like missions, we implement a Bayesian spectral inference framework that combines second-generation time-domain (TD) simulations of time-delay interferometry (TDI) with a frequency-domain (FD) spectral likelihood for stochastic gravitational-wave background (SGWB) analyses. The X, Y, Z Michelson streams generated with Triangle-Simulator are divided into finite segments, Fourier transformed, and modeled with a segment-dependent complex 3 x 3 covariance matrix. For each segment we evalua…

詳細を見る →
astro-ph.HE

Real-time observations of the transition to the quiescent state in an accreting magnetised neutron star: No propeller required?

Sergey S. Tsygankov, Galina Lipunova, Valery F. Suleimanov, Alexander Salganik, Alexander A. Mushtukov, Sofia V. Forsblom, Andrey S. Tavleev, Aleksei V. Kuzin et al.

The final stages of outbursts in transient X-ray pulsars (XRPs), which are characterised by a significant decline in the mass accretion rate, provide valuable insight into the physics of the accretion disc and its interaction with the strong magnetic field of the neutron star (NS). In particular, the `propeller effect', or centrifugal inhibition of accretion, has been proposed as a key mechanism governing both the onset luminosity and the timescale of the rapid transition to the quiescent state.…

詳細を見る →
physics.space-pheess.SYmath.OC

LQR Design For Formation Flying Near Halo Orbits Exploiting Quasi-Periodic Symmetry In Toroidal Coordinates

Joaquin G. Lopez-Cepero, Rafael Vazquez, Julio C. Sanchez

This work presents the design of a Linear Quadratic Regulator for relative motion control near periodic orbits in the Circular Restricted Three-Body Problem (CR3BP), formulated in non-singular toroidal coordinates. The key result exploits the rotational quasi-periodicity of the toroidal coordinate transformation. A uniqueness argument on the stabilizing solution of the associated difference Riccati equation proves the optimal control gains need only be computed for a single orbital period. The c…

詳細を見る →
astro-ph.GA

A Wandering 35,000-Solar-Mass Black Hole Fed by a Gravitational Wake

Xin Li, Yong Shi, Fuyan Bian, Junfeng Wang, Shude Mao, Qiusheng Gu, Yifei Jin, Yanmei Chen et al.

Intermediate-mass black holes are widely considered to be the seeds of supermassive black holes, a substantial population of which is expected to remain displaced from galactic nuclei owing to hierarchical galaxy assembly and inefficient dynamical friction. While several fueling channels can sustain central black holes, those pathways are largely inaccessible to off-nuclear black holes, leaving their fuel supply uncertain. As these wandering black holes move through the interstellar medium of th…

詳細を見る →
astro-ph.EP

Toward a unified framework for helium observations and interpretation of atmospheric escape

Carteret Yann, Bourrier Vincent

Atmospheric escape is considered a key process in shaping exoplanet demographics and evolution. The near-infrared metastable helium triplet (HeI at ~10833Å) is one of the most powerful tracers of hydrodynamical outflows. In recent years, a large variety of instruments have been used to detect and characterize expanding upper atmospheres. High-resolution (HR) spectrographs, which can spectrally resolve the lines of the triplet, have been mostly used to probe the dynamics of atmospheric escape. Mo…

詳細を見る →
astro-ph.HEgr-qchep-th

Transmutation Timescales for Dark Matter Induced Collapse of Compact Stars into Black Holes

H. A. Adarsha, Chandrachur Chakraborty, Sudip Bhattacharyya

Ultra-heavy asymmetric dark matter (DM) particles captured by compact stars can thermalize, self-gravitate, and collapse to form an endoparasitic black hole (EBH), whose subsequent growth may transmute the host star into a black hole. The continued existence of old millisecond pulsars (MSPs) and white dwarfs (WDs) thus places powerful constraints on the DM particle mass $m_χ$ and the DM-nucleon scattering cross-section $σ_{\rm nχ}$. We derive an analytical expression for the transmutation timesc…

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

Mapping the Inner Milky Way with Infrared-Derived Distances to AGB Stars

Rajorshi Bhattacharya, Subhajit Kar, Loránt O. Sjouwerman, Anupam Bhardwaj

The structure and evolution of the Milky Way (MW) can be traced with distance estimates to the evolved stellar populations in the inner galactic region. However, direct astrometric distances remain unavailable or highly uncertain for the majority of these sources due to instrumental limitations, large angular diameters, and complex variability. In this work, we develop a supervised machine-learning model to estimate statistical distances to oxygen-rich asymptotic giant branch (AGB) stars selecte…

詳細を見る →
gr-qcastro-ph.HE

Two-Fluid Schwarzschild Solution

Rico Zöllner, Burkhard Kämpfer

We consider the interior two-fluid Schwarzschild solution. That is a model of compact (neutron) stars with admixed dark matter. The two constant energy densities generalize the interior Schwarschild solution to the case of two fluids (representing standard model matter and dark matter, for instance), interacting mutually solely by the common gravitational field. In general, the two-fluid core is surrounded by a one-fluid corona (envelope). Only for special parameters (the model depends on energy…

詳細を見る →
astro-ph.IM

Comparing realtime optical gain measurement and methods on MagAO-X

Eden McEwen, Jared R. Males, Olivier Guyon, Sebastiaan Y. Haffert, Vincent Deo, Joseph D. Long, Logan A. Pearce, Laird M. Close et al.

A lingering technical challenge for pyramid wavefront sensors (PyWFS) is their change in response between calibration and correction residuals, a quantity known as optical gain (OG). Given the prevalent use of PyWFSs in current and planned high contrast adaptive optics (AO), understanding and reliably measuring OG for realtime control unlocks advanced correction and post processing techniques. The OG quantity as an unknown inhibits a system's ability to stably correct non common path errors, rec…

詳細を見る →
astro-ph.HEgr-qc

Electromagnetic responses driven by gravitational-wave memory in magnetar-flare outflows

Wen-Biao Han

An asymmetric relativistic outflow from a magnetar giant flare produces a step-like gravitational-wave (GW) memory. In the magnetized pair plasma surrounding the star, such GW memory drives transverse electromagnetic (EM) X-mode/fast-magnetosonic responses at the corresponding frequencies. We use this GW-memory spectrum to drive a global wave equation for a cold electron--positron pair plasma. With radiative boundary conditions excluding incoming waves, the driven response forms an outgoing EM m…

詳細を見る →
astro-ph.HE

Two new highly scattered fast radio bursts: evidence for scatter broadening by the circumsource medium

Joscha N. Jahns-Schindler, Keith W. Bannister, Adam T. Deller, Xinping Deng, Marcin Glowacki, Alexa C. Gordon, Vivek Gupta, Akhil Jaini et al.

We found two highly scattered Fast Radio Bursts (FRBs) during commissioning of the Commensal Realtime ASKAP Fast Transient COherent (CRACO) backend. FRB 240210D and FRB 240312D have scattering times of $34\pm6$ and $300\pm48$ ms, respectively, when scaled to 1 GHz. FRB 240312D originates near a spiral arm of a face-on galaxy at a redshift of only 0.05. Scintillation from a Milky Way screen constrains the distance of the scattering screen to $\sim 10$ pc from the source. FRB 240312D is therefore…

詳細を見る →
astro-ph.HE

JWST Spectroscopy of Type Ia Supernova 2025rbs from Maximum Light to the Nebular Phase

Lindsey A. Kwok, Stéphane Blondin, Adam A. Miller, Saurabh W. Jha, Willem B. Hoogendam, Cameron M. Pfeffer, Eyouel Z. Abate, Jennifer E. Andrews et al.

We present JWST observations of the Type Ia supernova (SN Ia) 2025rbs ($D=$14.5 Mpc) at +1, +23, and +84 days after B-band maximum, spanning peak light through a wavelength-dependent transition toward the nebular phase. Combined with ground-based optical and near-infrared (NIR) data, our panchromatic spectra (0.4-14 $μ$m) include the first maximum-light mid-infrared (MIR) spectrum and the earliest MIR spectroscopic sequence of an SN Ia to date. At peak light, the MIR spectrum exhibits a continuu…

詳細を見る →
astro-ph.EPastro-ph.SR

PDS 70 c and SR 12 c: Observational Constraints on Giant-Planet and Satellite Formation

Ignacio Mosqueira

PDS~70~c and SR~12~c are the only bound planetary-mass objects with secure cold submillimeter disk detections. Together they constrain giant-planet growth and satellite formation. The PDS~70 planets exhibit remarkable parallels to the Jupiter--Saturn pair in our Solar System. Both PDS~70 planets accrete within one shared gap, which links their final masses, the material reaching each Hill sphere, and the properties of the circumplanetary disk. Planetary torques deplete this finite reservoir, cau…

詳細を見る →
astro-ph.HE

An Optically Motivated Gamma-ray Study of Fermi-LAT Novae

Owen K. Henry, Timothy A. D. Paglione, David Zurek, Joshua Tan

High-energy (GeV) gamma-ray emission from nova eruptions was a surprise detection by the Fermi-LAT in 2010. Since then, it has been suggested that the gamma-rays from these systems are generated in collisionless non-relativistic shocks. In this theory, the observed correlation between optical and gamma-ray nova lightcurves naturally arises if a portion of the optical luminosity is reprocessed shock power. In this work, we investigate this scenario by analyzing Fermi-LAT-detected novae in varied…

詳細を見る →
gr-qcastro-ph.GA

Effects of Quantum Spin-Connection Foam in the Solar System, Galaxies, and the Universe

Igor V. Kanatchikov, Valery A. Kholodnyi

We argue that effects of the quantum spin-connection foam, which describes quantum gravity according to the precanonical quantization of General Relativity, may already be observed in the form of the small cosmological constant and a modification of Newtonian dynamics at small accelerations, manifested in the flat rotation curves of galaxies. We obtain a modification of the Newtonian potential that takes into account the existence of a fundamental small acceleration scale, $a_* = 8πG\hbar\varkap…

詳細を見る →
astro-ph.COastro-ph.HE

Evidence for Enhancement in the Rate of Fast Radio Bursts Toward Galaxy Clusters

Mawson W. Sammons, Airene Ahuja, Matt Dobbs, Zarif Kader, Evan Davies-Velie, Mohit Bhardwaj, Charanjot Brar, Amanda M. Cook et al.

Massive galaxy clusters can introduce gravitational lensing and populations of suppressed star formation member galaxies into the line of sight, potentially changing the distribution of observable sources toward them from that of the average sky. As a result, Fast Radio Bursts (FRBs) aligned with galaxy clusters can provide a unique window into parameter spaces of the FRB population that other lines of sight do not afford. In this study, we demonstrate that the second CHIME/FRB baseband catalog…

詳細を見る →
astro-ph.GA

Estimating the local star formation rate density from ASKAP RACS

Sonja Panjkov, O. Ivy Wong., Rachel L. Webster

Understanding the evolution of the cosmic star formation rate density (SFRD) is key to uncovering how the Universe arrived at its present state. This paper presents a novel and efficient method to estimate the local SFRD, which uses supervised machine learning to first identify a population of star-forming galaxies (SFGs). Next, star-formation rates (SFRs) are determined using the 1.4-GHz radio-continuum emission detected by the Australian Square Kilometre Array Pathfinder (ASKAP). Specifically,…

詳細を見る →
astro-ph.IM

Closed-loop Atmospheric Dispersion Correction for High-Contrast Imaging with MagAO-X

Katie Twitchell, Sebastiaan Haffert, Jared R. Males, Laird M. Close, Olivier Guyon, Kyle Van Gorkom, Alexander Hedglen, Parker T. Johnson et al.

Incoming starlight is refracted as it enters Earth's atmosphere from the vacuum of space. The wavelength-dependence of atmospheric refraction causes elongation of the broadband PSF of ground-based telescopes, especially in the visible spectrum. The result is degraded image quality alongside reduced coronagraph light-blocking efficiency, both of which limit high-contrast observations. An atmospheric dispersion corrector (ADC) is a dispersive optic used to compensate for this effect. Current metho…

詳細を見る →
astro-ph.GA

Scaling Relations of Galactic Outflows Across Cosmic Time: New Insights from Cosmic Noon

Tiffany Liou, Xinfeng Xu, Allison L. Strom, Nathalie A. Korhonen Cuestas, Claude-André Faucher-Giguère, Tim B. Miller, Gwen Rudie, Ryan F. Trainor et al.

Galactic outflows play a significant role in regulating galaxy evolution. Scaling relations between stellar mass ($M_\ast$), star formation (SFR), and outflow properties have been extensively studied at low redshifts ($z $ 50 for H$α$ or [OIII] $\lambda5007$) from Keck/MOSFIRE spectra, we detect warm-ionized outflows by decomposing lines into narrow and broad components. With the joint sample, we explore the redshift evolution of outflow scaling relations. On average, outflows at Cosmic Noon hav…

詳細を見る →
astro-ph.IM

windsoCC: reconstructing the wind-driven halo in MagAO-X images using wavefront sensor telemetry

Jay K. Kueny, Jared R. Males, Alycia J. Weinberger, Laird M. Close, Joseph D. Long, Joshua Liberman, Sebastiaan Haffert, Eden McEwen et al.

The wind-driven halo (WDH) is a persistent, low spatial frequency noise artifact that arises due to the servo-lag error inherent to all adaptive optics (AO) instruments. Spatial filtering may be employed to overcome this artifact, however, filtering out the WDH while simultaneously preserving signal from an extended astrophysical object of interest is exceptionally challenging. Additionally, since the WDH changes in intensity and position angle through an observation, data-driven algorithms (e.g…

詳細を見る →
astro-ph.IM

Lunar Reflective Interferometry

Peter W. Gorham, T. Joseph W. Lazio, Andrew Romero-Wolf, Patrick S. Allison, Marin M. Anderson, Ali M. Bramson, Roman Burridge, Amy Connolly et al.

We present the method of lunar reflection interferometry (\hbox{LRI}) in which a virtual interferometer can be formed by using a spacecraft-borne antenna in lunar orbit that receives both direct rays and those reflected from the lunar surface. The technique exploits the method of images and is akin to the classic "sea cliff" interferometer, with the Moon's surface, primarily the lunar Maria, replacing the ocean surface. We describe the method in detail, demonstrate that significant portions of t…

詳細を見る →
astro-ph.IM

Lunar Reflective Interferometry

Peter W. Gorham, T. Joseph W. Lazio, Andrew Romero-Wolf, Patrick S. Allison, Marin M. Anderson, Ali M. Bramson, Roman Burridge, Amy Connolly et al.

We present the method of lunar reflection interferometry (LRI) in which a virtual interferometer can be formed by using a spacecraft-borne antenna in lunar orbit that receives both direct rays and those reflected from the lunar surface. The technique exploits the method of images and is akin to the classic "sea cliff" interferometer, with the Moon's surface, primarily the lunar Maria, replacing the ocean surface. We describe the method in detail, demonstrate that significant portions of the Moon…

詳細を見る →
astro-ph.IMastro-ph.CO

Tabular foundation models for the estimation of probabilistic quasar photometric redshifts in S-PLUS

Raquel R. Valença, Lilianne Nakazono, Rafael Izbicki, Marco Henrique de Almeida Inácio, Bruno Marcondes e Resende, Maycon Jorge Deláqua da Silva, Kiana Coimbra Buin Lins, Natanael M. Cardoso et al.

We assess whether tabular foundation models can be used as off-the-shelf probabilistic photometric-redshift estimators for quasars in the 12-band S-PLUS DR6 survey, where colour-redshift degeneracies produce multi-modal posteriors and spectroscopic training sets are shifted relative to the photometric population. TabPFN 2.5, RealTabPFN 2.5, and TabICL are benchmarked against eight task-specific baselines, including linear conditional Gaussians, FlexZBoost, mixture-density networks, normalising f…

詳細を見る →
gr-qcastro-ph.HE

On the nature of oscillating modes of proto-neutron stars

Dimitra Tseneklidou, Alejandro Torres-Forne, Pablo Cerda-Duran, Martin Obergaulinger, Jose Antonio Font

Newborn proto-neutron stars (PNS) are potential targets of gravitational wave asteroseismology, the study of the (inner) structure of stars via their oscillation modes. To prepare for the eventual detection of such modes by current and future gravitational wave observatories, theoretical studies have obtained the possible spectrum of oscillations. However, there has been disagreement when it comes to identifying and classifying specific modes according to the physical mechanism that excites them…

詳細を見る →
astro-ph.HE

Astrophysical Constraints on Hadron--Quark Crossover in Hybrid Neutron Stars

Gábor László Kasza, György Wolf

We investigate astrophysical constraints on hybrid neutron-star equations of state constructed by combining an extended linear sigma model description of quark matter with several representative hadronic equations of state through a smooth hadron--quark crossover. Four different hadronic models are examined in order to explore the model dependence of the resulting hybrid equations of state. After imposing stability, causality, perturbative QCD matching, tidal deformability, and maximum-mass cons…

詳細を見る →
astro-ph.SR

Astro+ database. I. Description and first results

K. Rübke, A. Marco, I. Negueruela, A. Herrero, S. Simón-Díaz, H. M. Tabernero, L. R. Patrick

The vast amounts of spectroscopic data for massive stars provided by previous and existing instruments on ground-based and space-based telescopes have saturated our capability to process them by human inspection routines. Consequently, there is a pressing need for fully automatic machine-assisted tools to help handle incoming data. To this end, we present the development of a massive star spectroscopic interactive database, Astro+. We aim to provide users with a reliable, versatile, and user-fri…

詳細を見る →
astro-ph.SRastro-ph.GA

The Carbon Giant Population Revealed by Gaia DR3

Benjamin R. Roulston, Paul J. Green

Classical carbon stars (atmospheric C/O >1) are asymptotic giant branch (AGB) stars that become carbon-rich through third dredge-up during the thermally pulsing AGB phase. However, carbon stars also occur among red giants and main-sequence stars, where the carbon is thought to originate from binary mass transfer from a former AGB companion. Using the all-sky catalog of G 5^\circ$, we measure a local disk space density of $n_0=11\pm0.5\times10^{-8},\mathrm{pc}^{-3}$ and a scale height of $H_z=257…

詳細を見る →