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Research Trends

Latest preprints in space engineering and astrophysics.

astro-ph.SRastro-ph.GAastro-ph.IM

Probabilistic Stellar Age Estimation for Gaia XP Stars with NGBoost

Xiaokun Hou, Wenbo Wu, Gang Zhao, Haining Li, Jingkun Zhao

Stellar age is a fundamental quantity for Galactic archaeology, but reliable age estimation for large stellar samples remains challenging. In this work, we develop an uncertainty aware NGBoost framework for stellar age estimation using Gaia XP-derived atmospheric parameters and chemical abundances. Different from the standard NGBoost model, we modify the loss function by incorporating the uncertainties of the training age labels. We further use a Monte Carlo strategy to quantify the influence of…

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astro-ph.IMastro-ph.CO

gevolution 2.0: GPU-accelerated relativistic N-body simulations for cosmology

Julian Adamek, Øyvind Christiansen

High-performance computing is increasingly dominated by hardware acceleration using Graphics Processing Units (GPUs). To take advantage of this long-term trend, we implement a major overhaul of the parallelisation approach in the relativistic particle-mesh N-body code gevolution. The new version 2.0 of gevolution employs three layers of parallelisation: MPI for scalability on a distributed memory system, shared memory parallelisation on each MPI rank using OpenMP, and offloading all compute inte…

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astro-ph.SRastro-ph.IM

Solar, Heliospheric and Ionospheric Physics: Pathfinders, Precursors and SKAO Perspective

Pietro Zucca, Rohit Sharma, Divya Oberoi, Eduard Kontar, John Morgan, Peter Gallagher, Sven Wedemeyer, Biagio Forte et al.

The Solar, Heliospheric and Ionospheric (SHI) Physics Science Working Group of the Square Kilometre Array Observatory (SKAO) addresses the full chain of plasma processes linking the solar corona to the terrestrial environment. This overview chapter synthesises 16 topical contributions to Advancing Astrophysics with the SKA-II, spanning the quiet and active solar atmosphere, eruptive phenomena, heliospheric turbulence and solar-wind diagnostics, ionospheric science, stellar-solar connections, and…

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astro-ph.GA

Spatio-kinematical structure of the Galactic Nuclear Stellar Disk revealed in VLBI astrometry of circumstellar masers

Hiroshi Imai, Kohei Kurahara, Huib J. van Langevelde, Maria J. Rioja, Richard Dodson

SKA-VLBI astrometry will enable us to measure up to thousands of three dimensional motions of OH masers associated with circumstellar envelopes (CSEs) of OH/IR stars in the Nuclear Stellar Disk (NSD) and sites of high mass star formation in the Central Molecular Zone (CMZ) of the Galactic Center (GC). It is expected that the spatio-kinematical distribution of those OH masers should indicate the existence of a ring structure in the NSD, which has formed as a result of outward propagation of star-…

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astro-ph.HEastro-ph.GA

Black hole spin-mass correlation and vector resonant relaxation in gaseous star clusters: the origin of GW231123?

Zacharias Roupas

During the formation of a star cluster a spin-mass correlation of stellar black holes is generated as they grow via accretion of the residual gas. Moreover, the black hole spin tends to be anti-aligned with its orbital angular momentum in the cluster. We show that GW231123, reported by the LIGO-Virgo-KAGRA (LVK) collaboration, lies on our predicted high-mass, high-spin plateau of the spin-mass correlation with positive Bayesian evidence over the LVK prior. Furthermore, vector resonant relaxation…

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astro-ph.SR

Fast and periodic propagating disturbances along coronal loops detected with EUI on board Solar Orbiter

A. Dolliou, S. Mandal, K. Barczynski, T. Van Doorsselaere, D. Berghmans, C. Froment, F. Auchère, P. Antolin et al.

Recent high-resolution observations from the Solar Orbiter mission can help detect the indirect signatures of heating at the smallest scales. In this work we measure the properties and investigate the physical origin of propagating disturbances (PDs) in the intensity at the smallest resolvable scales with Solar Orbiter/EUI along coronal loops. We used two sequences of EUI/HRIEUV at high spatial (down to 125 km per pixel) and temporal resolutions (5 s of cadence). We placed slits along 13 active…

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

Revealing a multi-zone circumnuclear dust response in UGC~11487 through phase-resolved WISE W1--W2 diagnostics

I. O. Izviekova, O. V. Kompaniiets, I. B. Vavilova

Mid-infrared (MIR) flares provide a direct probe of dust reprocessing in obscured tidal disruption event (TDE) candidates when the primary optical or ultraviolet flare is weak, missed, or strongly attenuated. We present a phase-resolved analysis of the WISE/NEOWISE W1-W2 evolution of the MIR-selected TDE candidate UGC 11487/WTP14adeqka over 2014-2024. We combine timing, colour, and flux diagnostics with phenomenological modelling, hydrodynamically motivated clumpy dust-echo calculations, and an…

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astro-ph.IM

DESTINY: a new binding-energy-resolved astrochemical framework. Self-Consistent Competitiveness using Branched Absorbing Markov Chains

Maria Groyne, Cedric Baijot, Michaël De Becker

Under cryogenic interstellar conditions, the amorphous structure of interstellar ice results in binding-energy distributions (BEDs) per species. However, only few studies attempted their inclusion in astrochemical models. This paper introduces DESTINY, a deterministic astrochemical framework designed to incorporate BEDs while self-consistently accounting for the competition among activated surface processes. The framework is currently constrained to a monolayer. Surface processes initiated by su…

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astro-ph.COastro-ph.GA

Intracluster light and dark matter halo shapes reflect common assembly, not mutual coupling: shape correspondence in CDM but not SIDM

G. Martin, N. A. Hatch, W. Cui, A. Fernandez, Y. M. Bahé, M. S. Fischer, M. Montes, F. R. Pearce et al.

The intracluster light (ICL) has been proposed as a luminous tracer of the dark matter (DM) halo shape in galaxy clusters, with recent observational studies and $Λ$CDM simulations suggesting close alignment between the two components. We test whether this correspondence holds in a self-interacting dark matter (SIDM) cosmology using matched CDM and SIDM ($σ_\mathrm{DM}/m = 0.1$ and $0.5\;\mathrm{cm^{2}\,g^{-1}}$) hydrodynamical cluster simulations from TheThreeHundred project. We measure 3D axis…

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astro-ph.GA

Testing [O II] $\lambda3727$ as a Star Formation Rate Tracer in Quasar Host Galaxies

Xiaotong Feng, Xue-Bing Wu, Yuming Fu, Yuxuan Pang, Rui Zhu, Huimei Wang

The [O II] $\lambda3727$ emission line is a widely used star formation rate (SFR) tracer. However, its application to type I quasars is not straightforward, because the line can be affected by dust extinction, metallicity and contamination from the AGN narrow-line region (NLR). We test the reliability of [O II] SFRs using a sample of 202 SDSS and PG quasars, by comparing [O II] SFRs and reference far-infrared (FIR) SFRs derived from multiwavelength SED decomposition. We measure [O II], [O III],…

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

Binary White Dwarfs as Gravitational Wave Sources for LISA

Sreeta Roy, Surajit Kalita, Tomasz Bulik, Dorota Gondek-Rosińska

Gravitational waves (GWs) have proven to be a powerful probe of compact binary populations. In the millihertz frequency range accessible to Laser Interferometer Space Antenna LISA, binary white dwarfs (BWDs) are expected to constitute a dominant source, forming both individually resolvable signals and an unresolved Galactic background. In this work, we construct a Milky Way like population model and calculate the GW background from unresolved Galactic BWD in the LISA sensitivity range, with part…

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astro-ph.GA

Structural and dynamical properties of Tidal dwarf galaxies in the tails and bridge of the Guitar galaxy Arp 105

Jyoti Prakash, Kanak Saha

We present a multi-wavelength (far-ultraviolet to infrared) analysis of two tidal dwarf galaxy (TDG) candidates and a tidal bridge in the interacting system Arp 105 at $z = 0.029$ in the Abell 1185 cluster. Far-ultraviolet observations obtained with the Ultraviolet Imaging Telescope onboard AstroSat reveal strong FUV emission from the tidal galaxies Arp~105N and Arp~105S, indicating recent star formation. In Arp~105N, strong nebular emission lines and large equivalent widths $EW(Hα)=77.6\pm1.3$…

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astro-ph.GA

The stability of radially anisotropic rotating stellar systems with a central density cusp

Pierfrancesco Di Cintio, Anna Lisa Varri

We investigate the interplay between radial velocity anisotropy and internal rotation in self-gravitating systems characterised by initial spherical symmetry and a moderate density cusp. We study the stability properties of such configurations to disentangle the impact of anisotropy, rotation, and density structure on the formation of triaxial stellar systems. We perform a set of collisionless $N$-body simulations starting from initial equilibria with a phase space distribution function of the c…

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astro-ph.GA

Far-Infrared Star Formation Rates of Quasar Host Galaxies from Multiwavelength Spectral Energy Distribution Decomposition

Xiaotong Feng, Xue-Bing Wu, Yuming Fu, Yuxuan Pang, Rui Zhu, Huimei Wang

Reliable star formation rates (SFRs) are essential for studying the connection between black hole growth and quasar host galaxies. We study the far-infrared (FIR) SFRs and the host galaxy properties of 202 SDSS and PG quasars at $0.02<z\lesssim0.8$, spanning $\log({\rm SFR}_{\rm FIR}/M_\odot\,{\rm yr}^{-1})\simeq-0.45$--$2.76$, using multiwavelength spectral energy distribution (SED) decomposition. The photometry covers wavelengths from the optical to the FIR and is supplemented by JCMT/SCUBA-2…

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astro-ph.GAastro-ph.HE

Two Peas in a Pod: The First Confirmed Dual Active Galactic Nucleus within a Green Pea Galaxy System

Konstantinos Kouroumpatzakis, Peter G. Boorman, Jiří Svoboda, Ryan Pfeifle, Abhijeet Borkar, Maitrayee Gupta, Daniel Stern, Andreas Zezas et al.

The growth of galaxies in the early Universe is thought to be dominated by compact, intensely star-forming systems, yet the corresponding growth of supermassive black holes (SMBHs) within such environments remains poorly constrained. Green Pea galaxies are nearby analogs of rapidly assembling galaxies in the early Universe owing to their compact morphologies, intense star formation, low metallicities, and extreme ionization conditions. Although galaxy interactions are thought to trigger episodes…

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astro-ph.GA

Feature-driven anomaly flagging in obscured active galactic nucleus light curves with autoencoders

Natale De Bonis, Demetra De Cicco, Stefano Cavuoti, Ylenia Marruccia, Dragana Ilić, Andjelka B. Kovacević, Giuseppe Riccio, Simone Vaccaro et al.

Active galactic nuclei (AGN) are among the most complex classes of astrophysical objects, displaying a wide range of variability and observational properties. Identifying unusual AGN is crucial for understanding the physical mechanisms behind their emission better and for discovering potentially new subclasses or rare behaviors. With the increasing volume of data from next-generation surveys, machine-learning-based anomaly detection offers a promising approach to flagging and investigating such…

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astro-ph.IMgr-qc

Search for Planetary-mass Black Holes with an Improved Viterbi Algorithm

Raul Rodriguez, George Alestas, Sachiko Kuroyanagi, Juan Garcia-Bellido

Primordial black holes in the planetary-mass range have attracted renewed interest; however, the search for gravitational waves from such binaries remains challenging due to their long-lived nature. In this work, we present, define, and validate a fully operational search pipeline developed to detect planetary-mass binaries during their inspiral phase. We use the Viterbi algorithm, a dynamic programming technique that recovers the most likely track based on a Hidden Markov Model. To enhance its…

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astro-ph.SR

Sloshing Oscillations in coronal loops excited by successive M- and C-Class flares

Hitesh Paliwal, S. Krishna Prasad, M. V. Sunil Krishna

Slow magnetoacoustic waves in hot coronal loops have remained a topic of considerable interest and debate over the past two decades. The periodic back-and-forth motion of plasma within a coronal loop, often initiated by a flare, is commonly referred to as sloshing oscillation. In the present study, we report unprecedented observations of sloshing oscillations in coronal loops excited by successive M- and C-class flares, using data from the Atmospheric Imaging Assembly (AIA) onboard the Solar Dyn…

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astro-ph.SR

Dual-Perspective Microwave and Hard X-ray Constraints of Asymmetric Nonthermal Loops in an X-class Flare

Ruifei Huang, Yao Chen, Victor Melnikov, Alexey Kuznetsov, Zhao Wu, Dmitriy Smirnov, Sergey Anfinogentov, Feiyu Yu et al.

We report dual-perspective microwave and HXR observations of an X-class flare on 2024 May 15, taking advantage of the unique geometry of a front-side view from the Earth and a back-side perspective from the Solar Orbiter (SolO). Using spatially resolved imaging spectroscopy from Siberian Radioheliograph (SRH) together with Chashan Broadband Solar millimeter spectrometer (CBSmm) and STIX data, we identify a set of nonthermal flaring loops in an asymmetric magnetic field, with microwave sources lo…

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astro-ph.IM

The IRT Telescope on board the THESEUS mission

Diego Gotz, Aline Meuris, Eric Doumayrou, Dehbia Lattab, Frederic Pinsard, Samuel Ronayette, Thierry Tourrette, Herni Triou et al.

We present the Infra-Red Telescope (IRT), which is part of the payload of the THESEUS mission, one on the three phase A candidate missions for the M7 slot of ESA (launch date 2037). The IRT is a 0.7 m class telescope with an off-axis Korsch optical design, with imaging capabilities in the 0.7-1.8 microns range over a 15 x 15 arc min field of view. The IRT also provides slit-less low resolution spectroscopy (R~400) over a limited field of view of 2 x 2 arc min, in the 0.8-1.6 microns range. The g…

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astro-ph.HE

Time-dependent Accretion Disks in Tidal Disruption Events: Long-term Light Curves

Chenlei Guo, Erlin Qiao

The time-dependent accretion disk has been applied to explain the light curves observed in tidal disruption events (TDEs). Radiation pressure instability is expected to be an important factor that can shape the evolution of the accretion disk. In this paper, we upgrade the time-dependent disk model in Guo $\&$ Qiao by incorporating an index $μ$ (with the stress tensor $\propto p^μp^{1-μ}_{\rm{gas}}$, where $p=p_{\rm{gas}} + p_{\rm{rad}}$) for the modified viscosity, and a parameter $f_{\rm{w}}$…

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astro-ph.SR

CW Cas: A solar-type contact binary system with an unseen third companion in a hierarchical quadruple system

Azizbek Matekov, Liying Zhu, Linjia Li, Fangbin Meng, Nianping Liu, ShengBang Qian, Ergang Zhao, Mikhail Kovalev et al.

We present a comprehensive multiband photometric and spectroscopic study of the G-type binary CW Cas whose parameters have not been well determined. Our double-lined spectroscopic radial velocity curve of this system yields a reliable mass ratio of $q = 1.88(9)$. By combining $BVR_{c}I_{c}$ bands, TESS light curves and radial velocity curves, we found that CW Cas is a W-subtype shallow contact binary with a fill-out factor of 15\%. The components have masses of $0.98(6)M_{\odot}$ and $0.52(4)M_{…

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astro-ph.EPastro-ph.SR

Probing disk dynamics and dust evolution through shadows in protoplanetary disks: A case study of the HD 142527 disk

Yuya Fukuhara, Ryuta Orihara, Satoshi Okuzumi, Takayuki Muto

Planet formation begins with dust growth and planetesimal formation within protoplanetary disks surrounding young stars. To understand these processes, it is essential to estimate dust grain sizes from disk observations. In this study, we develop a new method to constrain grain size based on the estimation of cooling timescales. Our approach applies to transitional disks that possess an inclined inner disk casting shadows on the outer disk, whose temperature variations serve as a tracer of dust…

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astro-ph.IM

Optimal mode-sorting coronagraphy: limits of single-moded measurements for the Habitable Worlds Observatory

Yinzi Xin, Sebastiaan Haffert, Rico Landman

Conventional coronagraph architectures struggle to reach the theoretical limit of exoplanet detection at close working angles. Spatial mode-sorting is capable of reaching the theoretical limit, which previous work has calculated for a completely unresolved star whose signal lies entirely in the fundamental piston mode of the telescope. More recently, we have calculated optimized nulling modes as a function of the size of the star and planet parameters, with the goal of improving coronagraphic pe…

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astro-ph.GA

On the Separation Between the Brightest Cluster Galaxy and the Intracluster Light

Emanuele Contini, Sukyoung K. Yi

We present a model-based framework to define an aperture separation between the brightest cluster galaxy (BCG) and the intracluster light (ICL). Using the intrinsic BCG and ICL components predicted by the semi-analytic model \texttt{FEGA25}, we determine, for each halo, the aperture radius that minimizes the bias in the recovered ICL mass. The optimal radius is obtained by balancing the BCG stellar mass lying outside the aperture with the ICL mass enclosed within it. At $z=0$, the optimal apertu…

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gr-qcastro-ph.HE

Massive Compact Stars Beyond the General Relativity Limit in Finslerian Gravity: A Possible Explanation for the GW190814 Secondary

Praveen J, Rajesh Kumar, Sadaf Fatima, S K Narasimhamurthy

The existence of an upper mass limit for compact stars is one of the fundamental predictions of general relativity (GR), with important implications for the outcome of compact binary mergers and the nature of the proposed neutron star black hole mass gap. The LIGO Virgo collaboration announced the discovery of a compact binary merger, GW190814, containing a compact star with mass 2.5 to 2.67 $M_\odot$ [R. Abbott et al.(2020) ApJ Lett., 896, L44], which provided an exciting new stimulus to the on…

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astro-ph.GA

The Intrinsic Multiphase Gas--Black Hole Connection across Scales in IllustrisTNG

Xiaoxia Zhang, Taotao Fang, Shulan Yan, Si-Yue Yu, Feng Yuan

The relationship between supermassive black holes and the multiphase circumgalactic medium is central to understanding the co-evolution of galaxies and their central black holes. We investigate this relationship using the IllustrisTNG100 simulation with a sample of 5089 central galaxies at $z=0$, measuring the partial correlation between central black hole mass and the mass of cold ($T < 10^4$K), cool ($10^4 \le T < 10^5$K), warm ($10^5 \le T < 10^6$K), and hot ($T \ge 10^6$K) gas within $0.03R_…

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astro-ph.HE

Beyond Spin: QCD Magnetars

Rachid Ouyed

We present a unified framework in which anomalous X-ray pulsars (AXPs), soft gamma-ray repeaters (SGRs), superluminous supernovae (SLSNe-I), luminous fast blue optical transients (LFBOTs), and fast radio bursts (FRBs) originate from quark deconfinement in the core of a massive neutron star (NS). Spontaneous ferromagnetism in the deconfined phase generates ~10^18 G core fields, producing a highly magnetized hybrid star (HS) - the "QCD magnetar" - whose surface field is set by NS mass, not birth s…

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astro-ph.SR

First double red giant Algol system with active mass transfer

Mikhail Kovalev, Hailiang Chen, Sufen Guo, Jiao Li, Hongwei Ge, Dengkai Jiang, Marina Burlak, Natalia Ikonnikova et al.

Double red giant stars are very important for studies of the stability of mass transfer, common-envelope evolution, and the formation of double white dwarfs with short orbital periods. However, no double red giant system undergoing mass transfer has yet been found. We present the discovery of a close Algol-type binary system composed of two red giant stars. This is the first known semi-detached system observed during the very short phase when the accretor has expanded into a red giant just befor…

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astro-ph.GA

Anomalously high deuterium fractionation in a galactic translucent cloud: a challenge to chemical models

Gan Luo, Zhi-Yu Zhang, Thomas G. Bisbas, Di Li, Serena Viti, Roberto Neri, Junzhi Wang, Siyi Feng et al.

Deuterated (D-) species have long been proposed to diagnose the physical conditions and chemical evolution of cold dense molecular clouds. While deuterium fractionation has been extensively measured in dense cores, observations in diffuse and translucent clouds remain rare. We report here the detection of DCN and DNC toward a translucent cloud ($A_{\rm V} =1.2\pm0.2$ mag, $n_{\rm H_2}$ = $3.9\pm0.2\times10^2$ cm$^{-3}$) through sensitive absorption observations with the IRAM NOrthern Extended Mi…

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