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Research Trends

Latest preprints in space engineering and astrophysics.

astro-ph.SRastro-ph.HE

Dynamically driven collapse of a thermally stable accretion disk in a nova-like system

Wentao Li, Jie Lin, Tinggui Wang, Yongkang Sun, Chengyuan Wu, Heran Xiong, Krystian Iłkiewicz, Luca Casagrande et al.

While standard disk instability theory predicts thermal-steady, outburst-free disks in nova-like variables due to their high mass transfer rates, mass transfer variations are prevailingly invoked to explain the occasional flaring/fading phenomena observed in these systems. Here we report the observational evidence for a dynamical collapse of a thermally stable accretion disk, captured serendipitously by TESS during a fading episode of the VY Scl-type nova-like system MASTER OT J072703.91-631952.…

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astro-ph.SRastro-ph.HE

Dynamically driven collapse of a thermally stable accretion disk in a nova-like system

Wentao Li, Jie Lin, Tinggui Wang, Yongkang Sun, Chengyuan Wu, Heran Xiong, Krystian Iłkiewicz, Luca Casagrande et al.

While standard disk instability theory predicts thermal-steady, outburst-free disks in nova-like variables due to their high mass transfer rates, mass transfer variations are prevailingly invoked to explain the occasional flaring/fading phenomena observed in these systems. Here we report the observational evidence for a dynamical collapse of a thermally stable accretion disk, captured serendipitously by TESS during a fading episode of the VY Scl-type nova-like system MASTER OT J072703.91-631952.…

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hep-phastro-ph.IMhep-exphysics.acc-ph

Future of Artificial Intelligence for Science in Japan 2024 Community Report

Yoshitaka Itow, Jia Liu, Hirokazu Maesaka, Vinicius Mikuni, Nhat-Minh Nguyen, Hironao Miyatake, Atsushi J. Nishizawa, Patrick de Perio et al.

This white paper summarizes scientific challenges and AI/ML research opportunities identified through the FAIRS Japan 2024 unconference process. The discussion focuses on three major physics domains: accelerator physics, cosmology and astrophysics, and neutrino physics. Although each domain has distinct scientific goals and experimental constraints, several common technical themes emerge: high-dimensional reconstruction, fast and accurate simulation, uncertainty propagation, simulation-to-data m…

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astro-ph.SRastro-ph.GAastro-ph.HE

Quiescent and Interacting Compact Remnant Binary Populations in the Space Telescope Era

Erin Eastep, Jan J. Eldridge, J. C. Bray

Since the discovery of Gaia BH1, interest in quiescent binary systems has grown. Two additional black-hole binaries have since been discovered alongside several candidate neutron-star binaries, yet the formation pathways of these systems remain poorly understood. Theoretical studies of these systems, together with the populations into which they evolve, such as X-ray binaries (XRBs), can help constrain their formation channels. We present predictions for the Galactic population of quiescent bina…

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astro-ph.HEhep-ph

Low-energy antinuclei measurements for background-free indirect dark matter searches and PBH signatures

Tsuguo Aramaki, Ilias Cholis, Philip von Doetinchem, Fiorenza Donato, Priya Ghosh, Dan Hooper, Timothy Linden, Keith McBride et al.

Light low-energy cosmic ray antinuclei constitute powerful probes for detecting dark matter or other sources of new physics in our Galaxy. This ASTRA Initiative Mission Concept reviews the theoretical motivation, highlighting the transformative potential and current experimental status. Motivated by exciting tentative results, it makes a clear case for the need for the next flagship mission to confirm or refute claims of cosmic antinuclei as signs of new physics.

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astro-ph.IMastro-ph.HE

JUG: JAX-based Unified pulsar timinG

Matthew T. Miles, Stephen R. Taylor, Matthew Bailes, Aurelien Chalumeau, H. Thankful Cromartie, Kyle A. Gersbach, Rutger van Haasteren, Michael J. Keith et al.

We present JUG (JAX-based Unified pulsar timinG), a JAX-based, fully independent pulsar timing package emphasising speed and ease of use, designed to confidently handle the increasingly large and complex pulsar timing array datasets that are being created in the pulsar timing field. JUG implements the entire pulsar timing pipeline itself, from data handling and clock corrections through to the timing model and fitting, without relying on other timing software. It enables Pythonic programming at…

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astro-ph.GAastro-ph.HEastro-ph.SR

High Dispersion Measure Fast Radio Bursts from Young, Dust-Poor H II Regions

Eliza C. Diggins, Calvin Leung, Wenbin Lu

Several repeating fast radio burst (FRB) sources exhibit host-frame dispersion measure (DM) excesses far exceeding those expected from the interstellar medium in their host galaxies, implying a substantial contribution from the sub-kiloparsec-scale local environment. These excesses are often attributed to an expanding supernova remnant; however, this canonical interpretation does not explain their apparent preference for low-metallicity dwarf galaxy hosts, suggesting that the mechanism producing…

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astro-ph.IMastro-ph.HE

PolPy: A universal tool for X-ray/gamma-ray polarimetry using common data format standards

Sujay Mate, Hancheng Li, Utkarsh Pathak, Yashowardhan Rai, Nicolas De Angelis, Varun Bhalerao, Merlin Kole

X-ray/gamma-ray polarimetry has been a rapidly developing field in recent years. However, the lack of standardized analysis frameworks has hindered cross-instrument comparisons and joint multi-mission studies. To address this, we present PolPy, a universal tool designed for polarimetry of high-energy astrophysical transients. Built as a plugin for the Multi-Mission Maximum Likelihood (3ML) framework, PolPy introduces standardized data and response formats, common reference frames based on IAU co…

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astro-ph.GA

Near-Infrared Spectroscopy of Low-Redshift Palomar-Green Quasars and Composite Spectra

Amy Cavanaugh, Michael Brotherton, Jacob McLane, Richard Green

The Palomar-Green (PG) Quasars have been used extensively to establish the spectral properties of luminous active galactic nuclei (AGNs) at low redshifts in many wavebands, but not the near-infrared (NIR). We present NIR spectra of all 87 PG quasars with z < 0.5 observed with the Apache Point Observatory 3.5-m telescope and the TripleSpec spectrograph in standard cross-dispersed mode. Here we employ our data set to construct a NIR composite quasar spectrum spanning rest-frame wavelengths from ap…

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astro-ph.HE

The Impact of Errors in the Shape Function of Rotating Neutron Stars in the Oblate Schwarzschild Approximation

John Ming Ngo, Charlee Amason, Sharon M. Morsink

Measurements of thermal X-ray flux emitted by neutron stars can constrain their radii and the equation of state of cold dense matter. Accurate flux modeling of rapidly rotating neutron stars requires an approximation for their oblate surface shape, usually given by a shape function. We examine the accuracy of five shape functions by comparing them against numerical relativistic stellar surfaces for seven representative equations of state over a broad range of compactness and spin. We characteriz…

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astro-ph.GA

Overmassive supermassive black holes in SDSS close galaxy pairs

Maggie C. Huber, Julia M. Comerford, Joseph Simon

Supermassive black holes (SMBHs) and their host-galaxies coevolve through channels such as hierarchical merging and AGN feedback, establishing tight scaling relations between SMBH masses and properties of the host-galaxy. These scaling relations, particularly those with host-galaxy bulge mass (M${_\text{b}}$) and stellar velocity dispersion ($σ$), are widely used to estimate SMBH masses. Galaxy mergers drive gas into the centers of galaxies, enhancing SMBH growth and stellar bulge growth but not…

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astro-ph.HEastro-ph.SRphysics.space-ph

Magnetospheric birefringence breaks the rotating-vector model and depolarises X-ray pulsars

Alexander A. Mushtukov, Sergey S. Tsygankov, Silvia Zane, Nabil Brice, Ruth M. E. Kelly, Roberto Taverna, Roberto Turolla

Accreting X-ray pulsars have long been expected to show large linear polarisation below the cyclotron resonance. In the standard picture, this follows from two facts: radiative opacities in the strongly magnetised neutron star environment depend strongly on polarisation mode, and the emission comes from compact polar regions. The emerging radiation should therefore be locally polarised and add almost coherently, with a polarisation angle tracing the projected magnetic field as in the rotating-ve…

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astro-ph.HEastro-ph.SR

Spin-disc misalignment drives periodic accretion and pulse profile asymmetry in X-ray pulsars

A. A. Mushtukov, V. Ganesh, S. S. Tsygankov, S. Portegies Zwart, A. Palyam

We investigate magnetospheric accretion in disc-fed X-ray pulsars assuming that the neutron star spin axis is not perpendicular to the disc plane. We focus on X-ray pulsars, where a geometrically thin disc is truncated far from the stellar surface the channelled part of the accretion flow is expected to be guided by the large-scale dipolar magnetic field after coupling to it near the disc-magnetosphere boundary. Using numerical simulations of plasma motion from the inner disc edge to the neutron…

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astro-ph.SR

A 500 pc volume-limited sample of hot subluminous stars III. The short-period binary population

H. Dawson, M. Dorsch, J. Munday, S. Geier, F. Mattig, M. Pritzkuleit, D. Benitez-Palacios, M. Vučković et al.

Hot subdwarf stars of spectral types O and B (sdO/B) in binaries form as products of substantial mass loss near the tip of the red giant branch and offer powerful constraints on binary-star evolutionary models. However, details of some formation channels remain missing. We present a comprehensive analysis of the short-period binary population in the 500 pc volume-limited sample of hot subdwarfs, enabled by precise Gaia DR3 parallaxes. Besides 45 known binaries within 500 pc, this work identifies…

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eess.SYastro-ph.IMphysics.space-ph

Horizon-Dependent Tube MPC for Elliptical-Orbit Rendezvous Under Mass Uncertainty

Omer Burak Iskender, Keck-Voon Ling

A spacecraft closing on a target from three hundred kilometres to contact flies one guidance law across five orders of magnitude of range, and a controller that is provably safe at close range can lose that guarantee completely at long range while continuing to fly as though nothing were wrong. This paper derives the range at which the guarantee lapses and uses it as a design rule. The bound compares the prediction model's own linearisation error against the disturbance set the controller was bu…

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astro-ph.IMgr-qc

Toward a realistic test of black-hole movie correlations as a probe of extreme lensing

Barbora Bezděková, Shahar Hadar

In an optically thin setting, gravitational lensing around a black hole creates multiple delayed images of any localized source, appearing at different positions on the observer's screen. Even if particular sources cannot be singled out, this effect may be revealed in a black-hole movie (time-dependent image) by examining the two-point spatiotemporal correlation function of intensity fluctuations in the movie. Recently, the correlation function derived from a movie obtained by ray tracing of a g…

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astro-ph.SR

Spectral Synthesis for Classical Ae Stars: H$α$ and CaII

R. Anusha, T. A. A. Sigut

Classical Ae stars (CAe) are main sequence, A-type stars with H$α$ emission but no signature of dust; they are thought to be the cool extension of the classical Be (CBe) stars to lower stellar masses. We investigate the use of H$α$ and the CaII IR triplet observed at low spectroscopic resolution ($R=1800$) as diagnostics for the circumstellar disks of the CAe stars. Using a sample of 159 CAe stars from the LAMOST survey (DR5), we find that circumstellar disk masses and star/disk viewing inclinat…

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astro-ph.GA

Cluster Ages to Reconstruct the Milky Way Assembly (CARMA). V. The chronological merger tree of the Milky Way

Fernando Aguado-Agelet, Chiara Zerbinati, Davide Massari, Matteo Monelli, Santi Cassisi, Cristiano Fanelli, Carme Gallart, Edoardo Ceccarelli et al.

We present a new age determination of 24 globular clusters (GCs) dynamically associated with the main accretion events experienced by the Milky Way (MW), as part of the Cluster Ages to Reconstruct the Milky Way Assembly (CARMA) project's effort to trace the Galaxy's assembly history. We used deep and homogeneous archival Hubble Space Telescope data, and applied the CARMA isochrone-fitting code to derive homogeneous estimates of age, metallicity, reddening, and distance modulus for systems dynami…

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astro-ph.GA

Why is there cold gas inside the Local Bubble?

Tim-Eric Rathjen, Jeffrey L. Linsky

The Local Bubble (LB) extends approximately 100--200~pc from the Sun and contains $10^6$~K plasma and warm photoionised gas. Yet the Local Leo Cold Cloud (LLCC) and the Local Ribbon of Cold Clouds lie only 11--24~pc away, well inside the LB, at temperatures near 20~K. How such cold material forms and survives in this hotter environment remains uncertain, and explanations based on colliding warm clouds are difficult to test observationally. We investigate whether LLCC-like gas can assemble locall…

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astro-ph.SR

BSN-VIII: Detailed Photometric Modeling of Ten W UMa Contact Binaries and a Revised Empirical Period-Mass Relationship

Atila Poro, S. Javad Jafarzadeh, Kai Li, Jean-François Coliac, Sabrina Baudart, Meng Guo, Patrick Wullaert, David Valls-Gabaud et al.

This study continues our ongoing research on contact binary systems by presenting a detailed analysis of 10 targets. Ground-based observations from six different observatories were conducted and used together with TESS data for the analysis process. Photometric data from our observations were reduced with the recently developed AutoWISP pipeline, yielding high-quality light curves with reliable precision for analysis. An investigation of orbital period variations identifies long-term trends in s…

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astro-ph.HEastro-ph.GAastro-ph.SR

Formation of black hole stars via star--black hole collisions

Yanlong Shi, Qingru Hu, Zhenghao Xu, Douglas N. C. Lin, Norman Murray

In dense stellar environments such as globular clusters and active galactic nucleus (AGN) disks, stellar-mass black holes (sBHs) may frequently collide with massive stars. We investigate this process using semi-analytic models, three-dimensional hydrodynamical simulations, and one-dimensional stellar evolution calculations, focusing on collisions between sBHs and a $100\,M_\odot$ main-sequence star. We find that gas drag retains the BH within the stellar envelope unless the impact velocity excee…

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astro-ph.HEastro-ph.GAastro-ph.SR

Dynamical formation of high-eccentricity compact binaries through BH--BH*/TZO collisions

Qingru Hu, Yanlong Shi, Douglas N. C. Lin, Norman Murray

The rapidly accumulating discoveries of binary stellar-mass black-hole (sBH) coalescences, detected by LIGO, have opened a new window into the formation and evolution of compact binaries. In particular, residual orbital eccentricity may provide a distinctive signature of their formation channels. Here, we investigate a scenario in which high-eccentricity compact binaries form through the sequential capture of multiple sBHs by massive main-sequence stars, using a combination of hydrodynamical and…

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astro-ph.GAastro-ph.CO

The Limited Lifetime of Self-Gravitating Accretion Disks In Galactic Centers

Isaac Shlosman

Globally self-gravitating accretion disks in active galactic nuclei (AGN) have been frequently discussed in the literature, but never observed. Few dozen mega-masering accretion disks in AGN have been detected, which display a clear Keplerian rotation on scales of 0.1-1 pc, allowing to estimate their masses within the sphere of influence (SoI) of the central supermassive black holes (SMBHs) to be smaller by more than a factor of 10, compared with the parent SMBH masses. Furthermore, the stellar…

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astro-ph.GAastro-ph.COastro-ph.IM

Measuring Extragalactic Microlens Masses and Motions in Strongly Lensed Quasar Systems with Intensity Interferometry

Abigail Moran, Ken Van Tilburg

The direct measurement of masses and transverse motions of individual stars and compact objects in distant galaxies remains an outstanding challenge, leaving extragalactic stellar populations constrained only through model-dependent population fits. We show that time-resolved intensity interferometry of strongly lensed quasars, combined with flux-ratio photometry, can break the source-size, microlens-mass, and transverse-velocity degeneracies of conventional light-curve microlensing. Using the q…

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astro-ph.EPastro-ph.SR

Stellar Flares Rather than High $T_{int}$ As Possible Cause for the Missing Methane in Young Exoplanets: The Case Study of V1298~Tau\,b

Danica Adams, Pierre-Alexis Roy, Hilke Schlichting, Björn Benneke

Recent observations of V1298~Tau\,b, a warm sub-Neptune (R$=9.85 \pm 0.3\,R_\oplus$, M$=13.1 \pm 5.3, M_\oplus$, T$_\mathrm{eq} = 670\,$K) orbiting a young (10-30\,Myr) K star, show depleted methane and surprising abundances of CO$_2$ in its atmosphere. This makes the planet an interesting target to study the "missing methane problem", where HST, Spitzer, and JWST have revealed many sub-Jovian planets with effective temperatures cooler than 800\,K to be depleted in methane compared to equilibriu…

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astro-ph.GA

Dust and PAHs in late-stage galaxy evolution: Imprints of TP-AGB dust injection, grain growth and AGN feedback in high-z quiescent galaxies with JWST and ALMA

D. Donevski, A. Nanni, K. E. Whitaker, A. W. S. Man, A. Faisst, A. Lapi, I. García-Bernette, M. Romano et al.

A major unknown in late-stage galaxy evolution is what regulates the cold interstellar medium (ISM) after quenching, a question central to interpreting molecular gas, dust, and stellar content in quiescent galaxies (QGs) now probed by ALMA and JWST to $z\sim7$. We present the first semi-analytic model that follows the coupled post-quenching evolution of dust, cold gas, and polycyclic aromatic hydrocarbons (PAHs), using flexible star-formation histories and a framework tracking small and large ca…

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astro-ph.GA

Dust and PAHs in late-stage galaxy evolution: Imprints of TP-AGB dust injection, grain growth and AGN feedback in high-z quiescent galaxies with JWST and ALMA

D. Donevski, A. Nanni, K. E. Whitaker, A. W. S. Man, A. Faisst, A. Lapi, I. García-Bernete, M. Romano et al.

A major unknown in late-stage galaxy evolution is what regulates the cold interstellar medium (ISM) after quenching, a question central to interpreting molecular gas, dust, and stellar content in quiescent galaxies (QGs) now probed by ALMA and JWST to $z\sim7$. We present the first semi-analytic model that follows the coupled post-quenching evolution of dust, cold gas, and polycyclic aromatic hydrocarbons (PAHs), using flexible star-formation histories and a framework tracking small and large ca…

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astro-ph.HE

Exploring the capabilities of combined modelling strategies for supernova with relativistic jets using Redback

L. Cotter, N. Sarin, A. Martin-Carrillo

Events in which a supernova (SN) is associated with a relativistic jet present multi-component light curves. In the past, the analysis of such complex light curves was carried out largely by investigating each component individually due to limitations in modelling and inference. Such decoupled analyses are susceptible to biased parameter estimation due to cross-contamination between the emission of the relativistic jet and the SN. Additionally, differences in adopted methodologies make it diffic…

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astro-ph.COastro-ph.GA

TDCOSMO. XXVII. JWST-based Lens Models and H$_0$ Measurement of WFI2033, HE0435, and PG1115

D. M. Williams, T. Treu, D. P. Johnson, P. Mozumdar, S. Knabel, S. Birrer, C. D. Fassnacht, A. Galan et al.

Time-delay cosmography offers a one-step, distance-ladder-independent route to the Hubble-Lemaitre constant, H_0. We present new cosmography-grade lens models of three quadruply imaged quasars based on JWST-NIRCam/F115W imaging (WFI2033-4723, HE0435-1223, PG1115+080). We use the STARRED modeling technique, introduced in our previous analysis of WFI2033-4723, to reconstruct the complex JWST-NIRCam Point Spread Function at high fidelity. We combine NIRCam-based lens models with improved external c…

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astro-ph.GA

Resolved Dust in $z\approx1$ Galaxies with JWST/MIRI MRS: Survey Description and First View on PAHs, Mid-IR Atomic Emission, and Warm H$_2$

Wuji Wang, Andreas L. Faisst, Thomas S. -Y. Lai, Kyle Finner, Jed McKinney, Andrew J. Battisti, Irene Shivaei, Leindert A. Boogaard et al.

Dust is a key component of galaxies that regulates their thermal balance and, consequently, star formation and the build-up of stellar mass. Polycyclic aromatic hydrocarbons (PAHs) are responsible for reprocessing radiative energy of the galaxies thus tracing dust evolution. Using JWST/MIRI MRS, we present the first resolved view of the PAHs and mid-infrared emission lines in a sample of eight $z\approx1$ galaxies. A key novelty is our ability to directly map PAH emission near the end of cosmic…

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