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Research Trends

Latest preprints in space engineering and astrophysics.

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

From the Milky Way to the Early Universe: How Metallicity Shapes the Formation of Double Neutron Stars

Abhishek Chattaraj, Jeff J. Andrews, Monica Gallegos-Garcia, Max M. Briel, Michael Zevin, Tassos Fragos, Emmanouil Zapartas, David R. Aguilera-Dena et al.

Among the compact binaries detected through gravitational wave (GW) emission, double neutron stars (DNSs) hold the unique distinction of having well-characterized local analogs in the Milky Way. However, understanding their broader cosmological population remains challenging due to the complex metallicity-dependent evolution of their progenitors. Using the detailed binary population synthesis code POSYDON, we model DNS formation across a cosmological range of metallicities. We find that while DN…

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

Unravelling the Nature of AT\,2025abao: From Precursor to Final Fate

Zhuo Chen, Yingzhen Cui, Tianshu Wu, Yongzhi Cai, Hongwei Ge, Andrea Reguitti, Minxuan Cai, Lulu Fan et al.

Luminous red novae (LRNe) are potential signatures of common envelope evolution (CEE), a critical yet poorly understood phase in compact binary formation. AT\,2025abao, an LRN in the Andromeda galaxy, originated from an asymptotic giant branch (AGB) progenitor and exhibited a prolonged pre-outburst transient. Lacking direct constraints on the companion, however, the system's evolutionary fate remains unclear. Here, we unravel the binary nature of AT\,2025abao by modeling its complete evolution,…

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

Unravelling the Nature of AT 2025abao: From Precursor to Final Fate

Zhuo Chen, Yingzhen Cui, Tianshu Wu, Yongzhi Cai, Hongwei Ge, Andrea Reguitti, Minxuan Cai, Lulu Fan et al.

Luminous red novae (LRNe) are potential signatures of common envelope evolution (CEE), a critical yet poorly understood phase in compact binary formation. AT 2025abao, an LRN in the Andromeda galaxy, originated from an asymptotic giant branch (AGB) progenitor and exhibited a prolonged pre-outburst transient. Lacking direct constraints on the companion, however, the system's evolutionary fate remains unclear. Here, we unravel the binary nature of AT 2025abao by modeling its complete evolution, fr…

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astro-ph.HEastro-ph.SR

A Physically Motivated Compact Parameterization of Neutron Star Atmosphere Emission for Thermal X-ray Pulse-Profile Modeling

Tong Zhao, Renxin Xu

Thermal X-ray pulse-profile modeling depends on the angular and spectral properties of neutron star atmosphere emission. We construct a compact empirical approximation to the specific intensity using eight coefficients for the angular dependence and five for a normalized spectral kernel. The angular prescription is motivated by the formal solution of the radiative-transfer equation, while the spectral normalization preserves a specified bolometric flux. We calibrate this family to numerical atmo…

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astro-ph.SRphysics.flu-dynphysics.plasm-phphysics.space-ph

Fast and Differentiable MHD Surrogate for Solar Wind using Neural Operator

Prateek Mayank, Enrico Camporeale, Thomas E. Berger, Zhenguang Huang, Gabor Toth

Global magnetohydrodynamic (MHD) simulations provide the complete plasma state of the heliosphere, but their computational cost limits applications requiring repeated model evaluations. We introduce SNOW (Solar Neural Operator for Wind), a fast and differentiable surrogate for global MHD solar wind. SNOW combines a rotational ballistic approximation, a spherical harmonic neural operator, and causal radial context to autoregressively propagate all eight MHD variables from 20 to 240 Rs through con…

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astro-ph.IM

XuYi Interferometer Observation Simulator

M. Hadjara, T. Xu, Y. Sun, W. Wei, C. Liu, H. Zhang, J. Huang, C. Zeng et al.

The XuYi Interferometer is the first Chinese long-baseline optical interferometer currently under development by the National Institute of Astronomical Optics and Technology (NIAOT) of the Chinese Academy of Sciences. In preparation for future scientific operations, we developed the XuYi Interferometer Observation Simulator (XIOS), a lightweight MATLAB-based software package designed to assist observers in planning interferometric observations. The simulator combines target observability calcula…

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astro-ph.IM

BRICS Southern Observatory (BRICS-SO) Project: Invitation to African countries to invest in Chile

Massinissa Hadjara, Amokrane Berdja, Swagat R. Das, Elisson S. G. de Almeida, Slobodan Jankov, Vladmir Lukin, Abdelkarim Boskri, Zouhair Benkhaldoun et al.

Recently, the BRICS countries created a promising astronomy consortium (https://www.bricsastronomy.org/), which was joined last year by some emerging countries, including two African countries, namely: Egypt and Ethiopia. Certainly, other African countries will join BRICS+ in the years to come. Thus, by pooling their efforts, emerging countries (BRICS+) are sure to quickly catch up with their technological delay in the field of astronomy, particularly through ambitious and large-scale projects.…

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cs.AIastro-ph.IM

A Framework for Automated Multi-Source Satellite Data Analytics and LLM-Based Report Generation

Hind Yousif Alhammadi, Isam Mashhour Al Jawarneh

This paper presents the workflow for building an automated ArcGIS Pro tool using ArcPy to extract the Land Surface Temperature (LST) from Landsat 7, 8 and 9 datasets. The tool eliminates the need for manual band selection and repetitive raster computations by automating the multi-step workflow of radiometric calibration, NDVI-based emissivity correction, and thermal conversion. In addition to supporting batch and single-scene processing, the tool has an optional Large Language Model (LLM) for st…

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astro-ph.IMastro-ph.HE

Grid Optimization for Wide Field Modulation Collimators

Steven E. Boggs

Wide-field localization of transient sources such as gamma-ray bursts (GRBs) places new demands on the grid design of modulation collimators, whose usable field of view (FOV) is normally limited by self-vignetting. A grid slat thick enough to be opaque at the energies of interest also clips off-axis rays, shrinking the effective slit width and ultimately defining the FOV itself. Historical bigrid or rotating-modulation-collimator (RMC) designs have been designed with this trade-off as an unavoid…

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astro-ph.IM

WEEVIL: design and commissioning of an ice-sublimation chamber and a cryogenic submillimeter radiometer for studying rarefied gas plumes

D. Belousov, J. Fritschi, O. Mokhtari, L. L. Stöckli, D. Piazza, A. Murk, N. Thomas

We present WEEVIL (WatEr Emission of Vapor from Ice in the Laboratory), an experimental facility developed to study ice sublimation under laboratory conditions to support observations of comets and icy moons. The setup combines a submillimeter heterodyne radiometer and a high-vacuum cryogenic chamber, enabling spatially and temporally resolved monitoring of gas plumes formed during ice sublimation under controlled laboratory conditions. This paper describes the facility's design and implementati…

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astro-ph.SR

ZTF J191814.28+010850.2: An eclipsing cataclysmic-variable candidate in the SW Sextantis period range

Klaus Bernhard, Wolfgang Moschner, Christopher Lloyd, Peter Frank

We present a photometric study of ZTF J191814.28+010850.2, a short-period variable previously classified as an EA-type eclipsing binary. The analysis is based on ZTF observations in the g and r bands and additional time-series CCD photometry obtained on two nights. We derive an eclipse period of 0.1408529(3) d. The phased ZTF light curves show a deep primary eclipse, with an eclipse depth of about 2.8 mag in g and 2.0 mag in r, as well as indications of cycle-to-cycle variations outside eclipse.…

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astro-ph.GA

ALMA Observations of Molecular Complexity in the Large Magellanic Cloud: The N83 Star-Forming Region

Marta Sewiło, Amanda Broadmeadow, Roya Hamedani Golshan, Steven B. Charnley, Lee Mundy, Kazuki Tokuda, Thomas Möller, Jennifer Wiseman et al.

We report the results of the 1.2 mm continuum and molecular line $\sim$0.1 parsec-scale observations with the Atacama Large Millimeter/submillimeter Array of two fields in the star-forming region N83 in the Large Magellanic Cloud (LMC). This study is third in a series of investigations exploring molecular complexity in a low-metallicity and high UV flux environment of the LMC. We determine the physical and chemical properties of five sources detected with ALMA based on spectral modeling with XCL…

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astro-ph.SRastro-ph.GAastro-ph.IMphysics.comp-ph

AI Agents as a Research Team: A Human-Supervised Case Study in Stellar Spectroscopy

Marwan Gebran, Ian Bentley

We present a qualitative case study of a human-supervised team of specialized AI agents supporting an astronomy research project. The Bot Spectroscopist team, described in the project record as operating through Grok Bot powered by xAI Grok, divided work among orchestration, numerical implementation, data curation, spectroscopy critique, literature search, figure preparation, manuscript editing, and review. Human decisions determined scientific scope, model changes, and manuscript inclusion. The…

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astro-ph.HEphysics.plasm-ph

Radiation Reaction in Relativistic Magnetized Shocks of Neutron Star Magnetospheres

Arno Vanthieghem, Amir Levinson

The steepening of fast magnetosonic waves in the inner magnetospheres of magnetars can produce monster shocks, whose precursor emission may account for fast radio bursts (FRBs). For sufficiently bright bursts, particles crossing the shock radiate their energy within a single gyration period, raising the question of how radiation reaction affects the shock structure and its coherent emission. We investigate strongly cooled, relativistically magnetized shocks using a stationary multifluid model ge…

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physics.space-phastro-ph.EPastro-ph.IM

What Caused the Orbital Decay of the Twin Van Allen Probes to Diverge?

Ayisha M Ashruf, Ankush Bhaskar, C Vineeth, Tarun Kumar Pant

The Van Allen Probes were launched into nearly identical orbits and experienced the same solar and geomagnetic environment, yet their post-mission lifetimes diverged dramatically. Probe A underwent rapidly accelerating orbital decay and reentered the atmosphere in March 2026, while Probe B remains in orbit. We investigate the cause of this divergence using reconstructed orbital trajectories, modeled thermospheric densities, and measures of low-altitude residence and atmospheric drag. We find tha…

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physics.hist-phastro-ph.EP

Astronomia Ova: Kepler's Laws, Ptolemy's Equant, and Legendre's Polynomials

Cristopher Moore, Malcolm Smith, Stephan Mertens

Motivated by Kepler's long battle with the orbit of Mars, we present a family of orbits that satisfy his second law, conserving angular momentum around a central mass, and also fulfill Ptolemy's belief in an equant --- a point around which the angular speed is constant. For specific values of the angular momentum, these orbits can be written in terms of Legendre polynomials and functions of the second kind. They are analytic except at perihelion where they are twice differentiable. They resemble…

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astro-ph.HEastro-ph.COastro-ph.GA

A Brush with Turbulence: Probing the ICM Dynamics in the Merging Toothbrush Cluster using XRISM

Anjali Madangarli, Aurora Simionescu, Huub Röttgering, Anwesh Majumder, Soeda Haruse, Kazuhiro Nakazawa, Yuusuke Uchida, Daisuke Ito et al.

The Toothbrush Cluster (1RXS J0603.3+4214) is known for its northern radio relic, radio halo, and highly disturbed X-ray morphology. It shows features of both shock-driven and turbulent reacceleration, the latter of which is invoked to explain its radio halo. However, how kinetic energy from the merger is distributed into gas motions across spatial scales remains unclear. We probe the intracluster medium (ICM) dynamics in the southern, X-ray-brightest region of the cluster using a 167 ks XRISM/R…

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hep-exastro-ph.IM

Precision measurement of ocean tides using cosmic-ray muons

Jiwon Seo, Jongseok Chung, Chang Hyon Ha, TongZhou Huang, Jinyoung Kim, Sooa Kim, Hani Kimku, Byoung-cheol Koh et al.

Cosmic-ray muons provide a natural probe of the integrated mass along their trajectories. Here we show that cosmic-ray muons can monitor ocean-tide-induced variations in seawater overburden within an underwater tunnel. The observed modulation closely tracks independent tide-gauge measurements, yielding an attenuation response coefficient of $k=43.2\pm1.0$~counts$\rm /h/m$ and resolving meter-scale variations in seawater overburden. A spatial muography scan validates the overburden model, confirm…

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astro-ph.EP

Irradiated Atmospheres VII. Effect of Mixing Energy Flux on Atmosphere-Interior Coupling}

Wei Zhong, Zhen-Tai Zhang, Mei Ting Mark, Xiang-Xing Chen, Bo Ma, Xian-Yu Tan, Cong Yu, Dong-dong Ni et al.

Highly irradiated, underdense rocky planets such as puffy Venuses may host strong coupling between their atmospheres and magma-ocean interiors. Previous studies have mainly treated this coupling through radiative transfer and chemical equilibrium, leaving the role of vertical mixing unclear. Here we quantify how energy transport associated with vertical mixing modifies the thermal structure, volatile chemistry, and emission spectra of puffy Venuses. Atmospheric circulation and gravity-wave break…

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astro-ph.EP

Irradiated Atmospheres VII. Effect of Mixing Energy Flux on Atmosphere-Interior Coupling

Wei Zhong, Zhen-Tai Zhang, Mei Ting Mak, Xiang-Xing Chen, Bo Ma, Xian-Yu Tan, Cong Yu, Dong-dong Ni et al.

Highly irradiated, underdense rocky planets such as puffy Venuses may host strong coupling between their atmospheres and magma-ocean interiors. Previous studies have mainly treated this coupling through radiative transfer and chemical equilibrium, leaving the role of vertical mixing unclear. Here we quantify how energy transport associated with vertical mixing modifies the thermal structure, volatile chemistry, and emission spectra of puffy Venuses. Atmospheric circulation and gravity-wave break…

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astro-ph.HE

Pulsations and constraints on time lags in two distinct ULXs: NGC 5204 X-1 and NGC 55 ULX-1

Sathyaprakash, Rajath, Middleton, M. J., Done, C

The nature of ultra-luminous X-ray sources (ULXs) is shrouded in mystery as they're believed to be point sources with luminosities above the classical Eddington limit for a 10$M_{\odot}$ black hole (BH), but generally fit into the classification tree of super-Eddington X-ray binaries. Studies of reverberation lags and lag-energy spectra provide some insight into the nature of viscous turbulence in optically thick, super-Eddington discs, and are useful in conjunction with modelling multi-waveleng…

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astro-ph.HE

Pulsations and constraints on time lags in two distinct ULXs: NGC 5204 X-1 and NGC 55 ULX-1

Rajath Sathyaprakash, Matthew J. Middleton, Chris Done

The nature of ultra-luminous X-ray sources (ULXs) is shrouded in mystery as they're believed to be point sources with luminosities above the classical Eddington limit for a 10$M_{\odot}$ black hole (BH), but generally fit into the classification tree of super-Eddington X-ray binaries. Studies of reverberation lags and lag-energy spectra provide some insight into the nature of viscous turbulence in optically thick, super-Eddington discs, and are useful in conjunction with modelling multi-waveleng…

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

Large offsets of double-neutron-star mergers: degeneracies and implications for host associations

Xiao-Tian Xu, Bin-Bin Zhang, Wenjie Wu, Suoning Wang

The projected offset of a Gamma-Ray Burst (GRB) from its host galaxy is an important diagnostic of its physical origin, where the host associations are usually evaluated through chance-coincidence probabilities. However, as shown by observations, the host associations given by this approach may be ambiguous in some cases. In this work, we revisit the modelling of the offsets of double-neutron-star (DNS) mergers with controlled numerical experiments using Monte Carlo simulations. To isolate the d…

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astro-ph.GA

Spatio-temporal progression of star formation in the Carina OB1 association

C. Göppl, T. Preibisch

The Carina OB1 association, harboring the famous Carina Nebula near its center, is the most massive, well-studied OB association in our Galaxy. Containing several massive star clusters with different ages, it shows a complex spatio-temporal structure. We explore the formation history and kinematic evolution of the eight most massive clusters in Car OB1. We determine the cluster ages, stellar populations, the initial massive star content, and the number of supernova explosions since the time of e…

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astro-ph.HEnucl-thphysics.comp-ph

Fast Bayesian Updating of the Neutron-Star Equation of State with Neural Posterior and Evidence Estimation

Prashant Thakur

We present two complementary neural routes for microscopic neutron-star EOS inference: truncated sequential neural posterior estimation with mixture importance sampling (TSNPE+MIS), which targets one observation, and amortized neural posterior estimation with importance sampling (A-NET+IS), which is reused across nuclear inputs and NICER sources. Both are corrected against the original prior and full likelihood, with the effective sample size as a diagnostic. We test nucleonic and hyperonic rela…

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astro-ph.SRastro-ph.GA

SPHERE/ZIMPOL observations of the symbiotic system R Aquarii. II. Dynamics of the dust in the Mira wind and the Halpha gas in the jet

H. M. Schmid, E. Lagadec, J. Milli, C. Tschudi, J. Ma, N. Engler, J. L. Beuzit, A. Boccaletti et al.

R Aqr is a resolved symbiotic Mira binary and a prototype target for the study of complex hydrodynamic processes including dust-driven mass loss, mass transfer, accretion, and jet outflows and the formation of strongly asymmetric structures. We investigate for R Aqr the central Halpha emission from the ionized gas and the polarization from scattering dust based on SPHERE/ZIMPOL maps with a resolution of about 25 mas (5 AU). Data for four epochs were taken, including the dust eclipse around 2021,…

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astro-ph.GA

Large-Scale Stellar Bars and Nuclear Activity in Narrow-Line Seyfert 1 Galaxies

Po-Chieh Yu

We present a statistical comparison between barred and unbarred narrow-line Seyfert 1 galaxies (NLS1s) to investigate the role of large-scale stellar bars in fueling AGN with low-mass black holes. From a parent sample of 492 NLS1s selected from SDSS and Pan-STARRS1 (PS1), we construct a PS1-resolved matched sample of 101 barred and 101 unbarred NLS1s, matched in redshift, inclination, and image quality. Unbarred NLS1s are modestly but consistently brighter than barred NLS1s in several optical AG…

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astro-ph.IM

Opportunity Lost in Searching for Technosignatures

Steve Prabu, David DeBoer, Andrew Siemion, Andre R. Offringa, Natasha Hurley-Walker, Charlie K. Ashe, Sofia. Z. Sheikh, Steve Croft et al.

The sensitivity of radio technosignature searches has improved dramatically over the last five decades; however, as the RFI environment from which these searches are conducted has become increasingly polluted, our advancements in telescope sensitivity have not necessarily been complemented by less ambiguous technosignature searches. In this work, we investigate the resulting loss of opportunity to conduct unambiguous technosignature searches from Earth. We introduce three new concepts, \textsf{o…

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astro-ph.EP

Candidate O I 7774 Å Absorption from an Escaping Rock-Vapor Outflow of BD+05 4868 Ab

Kody M. Walker, James C. Wallace

Disintegrating rocky planets provide a rare opportunity to probe material escaping directly from intensely irradiated planetary surfaces. We present time-resolved, low-resolution ($R\simeq600$) optical spectroscopy and complementary ground-based photometry of BD+05 4868 Ab. The in-transit spectra exhibit an additional unresolved absorption feature near the O I triplet at 7771.94, 7774.17, and 7775.39 Angstroms relative to the out-of-transit baseline. The feature has an equivalent width of $W_λ\s…

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astro-ph.EPastro-ph.GA

Spectral Energy Distribution and Polarimetric Properties of Dust in the Interstellar Comet 3I/ATLAS

Seungwon Choi, Masateru Ishiguro, Hiroyuki Naito, Yoonsoo P. Bach, Jooyeon Geem, Bumhoo Lim, Moonkuk Hur, Sihu Ahn et al.

The interstellar comet 3I/ATLAS exhibits unusual polarimetric properties compared with Solar System comets, while constraints on its fundamental physical properties, such as dust albedo and grain-size distribution, remain limited. We obtained new optical polarimetry near opposition with the Pirka Telescope, combined it with previously reported polarimetric measurements, and constructed a visible-to-mid-infrared spectral energy distribution (SED) from HST, VLT, SPHEREx, and JWST observations. The…

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