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Research Trends

Latest preprints in space engineering and astrophysics.

astro-ph.GA

The Large Magellanic Cloud through the lens of the James Webb Space Telescope: Binaries and the mass function in the galaxy's outskirts

M. V. Legnardi, F. Muratore, A. P. Milone, G. Cordoni, E. Dondoglio, L. N. Gorza, A. Bellini, F. Calura et al.

Nearby galaxies such as the Large Magellanic Cloud (LMC) offer an ideal laboratory to test the initial mass function under different physical conditions, but previous works have been limited by photometric depth and have therefore poorly constrained the low-mass regime. Here, we analyze ultra-deep James Webb Space Telescope observations of a field in the LMC outskirts, near the intermediate-age and massive star cluster NGC 1846. Using the $m_{\rm F322W2}$ versus $m_{\rm F115W}-m_{\rm F322W2}$ co…

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hep-phastro-ph.HEhep-ex

Astrophysical Neutrino Sources as Colliders

Carlos A. Argüelles, P. S. Bhupal Dev, Bhaskar Dutta, Gonzalo Herrera, Nicholas Kamp, Jason Kumar, Stephan A. Meighen-Berger, Mudit Rai et al.

High-energy neutrinos arise from processes at large center-of-mass energies, offering a window to test physics at comparable scales or beyond those accessible in collider experiments on Earth. Here, we present a recipe for extracting two-sided bounds on the inelastic $pp$ and $pγ$ cross sections from neutrino point-source data, by independently constraining every astrophysical input (cosmic-ray luminosities and target densities) through electromagnetic observations or theoretical arguments. The…

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astro-ph.IM

NAPTIME: A Neural-Process Framework for Rubin Alert Classification

Nicholas Earl, Siddharth Chaini, K. Decker French, Jason T. Hinkle, Yashasvi Moon, Margaret Shepherd

The Vera C. Rubin Observatory Legacy Survey of Space and Time will produce a high-volume stream of irregularly sampled multiband alerts for which spectroscopic confirmation will be available only for a small minority of sources. Tidal disruption events are rare phenomena that provide a direct probe of dormant massive black holes, but their light curves can be confused with nuclear variability and other transient subclasses. We present NAPTIME (Neural Astrophysical Photometric Transient Identific…

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astro-ph.SR

Testing Theories of Solar Coronal Heating with Three-Dimensional Forward Modeling

Steven R. Cranmer, Chris R. Gilly

After almost a century of speculation, the physical processes responsible for heating the Sun's corona remain uncertain. Observations of coronal loops at extreme ultraviolet and X-ray wavelengths have provided substantial insights, such as the constraint that heating rates increase monotonically with local magnetic field strength. However, there remain dozens of competing suggestions for detailed theoretical explanations of the heating. There remains a need to compare the predictions of these th…

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astro-ph.SRastro-ph.HE

Will a Supernova explode in CD-30°11223?

L. Piersanti, L. R. Yungelson, E. Bravo, I. Dominguez

Context: Accretion of He-rich matter onto a low mass carbon-oxygen white dwarf in a binary system with a He-rich donor may lead to an explosive event of Supernova Ia proportion, though with low peak luminosity and peculiar nucleosynthesis. Recently such a statement has been questioned, suggesting that, if the effects of rotation are accounted for in the evolution of the accretor, the latter does not explode, but it becomes a white dwarf with a massive He-buffer. Aims: We investigate the expected…

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nucl-thastro-ph.HEhep-phnucl-ex

Quarkyonic Stars with Strangeness

Jin-Biao Hu, Jun-Ting Ye, Si-Pei Wang, Rui Wang, Zhen Zhang, Lie-Wen Chen

We propose an extension of the quarkyonic matter framework that includes $u$, $d$, and $s$ quarks and the full baryon octet. Within this extended framework, we impose beta-equilibrium between baryons and leptons, while determining the quark fractions from the constituent quark contents of baryons. The hadronic sector of octet baryons is described by a recently developed density, momentum and isospin dependent effective interaction based on the N3LO Skyrme pseudopotential, whereas quarks and lept…

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astro-ph.SR

Identifying and Determining Atmospheric Parameters of BHB Stars Based on LAMOST DR11

Xiao-Long Wang, Wen-Yuan Cui, Jie Ju, Guo-Zhen Hu, Min Fang, Shuai Zhang, Jia-Ming Liu

Large catalogs of blue horizontal-branch (BHB) stars are essential for studying substructures and kinematics of the Galactic halo. And accurate determination of atmospheric parameters for BHB stars provides insight into stellar evolution. In this work, we perform a systematic search for BHB stars based on LAMOST DR11, and identify $13\,988$ BHB spectra, corresponding to $10\,236$ unique BHB stars. We estimate an identification rate of $\sim80\%-90\%$, and a contamination rate of $\lesssim10\%$ f…

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astro-ph.SR

Determination of the horizontal velocity field in the solar atmosphere: Method validation using 3D MHD model

Andrii Prysiazhnyi, Oleksandra Baran

We present an improved version and further validation of a method, originally introduced by Stodilka (2016), for reconstructing horizontal velocity fields in the solar atmosphere from physical parameters typically derived from spectroscopic observations through inversion techniques. This approach relies on the continuity equation and the assumption of negligible vertical vorticity. Several algorithmic modifications were implemented to allow application to large spatial grids, including the compa…

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astro-ph.GA

Physical Properties of 6.7 Million Galaxies from the DESI Bright Galaxy Survey: Spectral Fitting and Systematic Tests with Mock Spectra

Niu Li, Hu Zou, Jinfu Gou, Weijian Guo, Wenxiong L, Haoming Song, Jipeng Sui, Xi Tan et al.

We present a comprehensive analysis of the physical properties of galaxies in the Dark Energy Spectroscopic Instrument (DESI) Data Release 1 (DR1) Bright Galaxy Survey (BGS), based on full spectral fitting of $\sim 6.7$ million galaxy spectra. Using a customized spectral fitting pipeline, we derive key physical parameters including stellar mass, stellar velocity dispersion, stellar population age, dust attenuation, and emission-line properties. To quantify the reliability and systematic uncertai…

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astro-ph.SR

Optical Spectroscopy and Temporal Evolution of the Nova V1405 Cas

Gesesew R. Habtie, Ramkrishna Das, Elias Aydi, Pavol A. Dubovsky

This paper presents the findings from our study of nova V1405~Cas over the first 1051 days after the outburst. The study includes an analysis of the photometric light curve evolution, along with a detailed spectroscopic evolution. Photometric analysis shows that the nova is a very slow nova, with a decline timescale of $t_2 \approx 165$ days. The mass of the white dwarf is calculated as \( M_{\rm WD} \sim 0.7M_{\odot} \). The secondary star is a low-mass main-sequence star, with a mass of \( M_{…

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astro-ph.EP

Dynamical formation of long-period exoplanets systems in evolving binary stars

Isabel J. Lima, Rafael R. Sousa, Silvia M. Giuliatti Winter, Diogo Belloni, Ernesto Vieira, Rosana A. N. Araújo, Eder Martioli

The dynamical formation and evolution of long-period giant exoplanets have not been well constrained due to the few observational parameters. In this study, we explore the dynamical effects in a multi-planetary system around one star of an evolving wide binary system. We used an interpolated result of a MESA stellar evolution inside REBOUND N-body integrations to perform simulations with a range of distinct planetary masses in a circumstellar configuration (S-type orbit), centered on a primary s…

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astro-ph.HE

Modes in Transitional Millisecond Pulsars: Evidence of Pulsar Wind-Induced Disk Heating from GRMHD and Radiative Transfer

Mignon-Risse Raphaël, Linares Manuel, Parfrey Kyle, Tchekhovskoy Alexander, Ressler Sean

Transitional millisecond pulsars (tMSPs) alternate between radio and X-ray pulsar states, and can represent the missing link between rotation- and accretion-powered neutron stars. Their disk state switches stochastically between the low and high X-ray modes, both of unknown physical origin and less luminous than low-mass X-ray binaries. To reveal the source of the X-ray emission, we carry out 2D axisymmetric general-relativistic magnetohydrodynamical simulations of the interaction between an acc…

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astro-ph.GA

An (in)complete NIRSpec census of Balmer absorption in Type 1 AGN -- radiation-driven outflows in little red dots, quasars and variable stars

Ignas Juodžbalis, Xihan Ji, Francesco D'Eugenio, Jan Scholtz, Roberto Maiolino, Amanda Stoffers, Alessandro Marconi, Elena Bertola et al.

A notable achievement of the first generation of JWST surveys was the discovery of an abundance of faint high-redshift ($z > 4$) broad-line active galactic nuclei (AGN) in the $L_{\rm bol} < 10^{45}$~erg~s$^{-1}$ regime, previously only accessible at $z < 1$. The high prevalence of absorption features in their broad hydrogen lines is one of the peculiarities of a significant fraction of this new population. In this paper, we conduct a broad census of Balmer absorption in a sample of 47 Type-1 AG…

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astro-ph.SR

Consistent Multi-Wavelength Spectral Modeling of Cool White Dwarfs with Carbon-Polluted Atmospheres

Jay Farihi, Piotr M. Kowalski, Sandy K. Leggett, Hania Azzam, Jackson Headon, John P. Subasavage

This work presents atmospheric modeling of multi-wavelength spectra for eight cool white dwarfs with carbon-enriched atmospheres, with four each of spectral type DQ and DQp. The Deslanders-d'Azambuja bands of C2 are detected in all six DQ stars that have data covering wavelengths shorter than 4000A. These bands are blue shifted in the DQp types, consistent with that observed for the Swan bands, and reproduced with the same pressure distortion model. The coolest stars in the sample show significa…

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astro-ph.HEastro-ph.SR

Be/X-Ray Binaries: Phenomenology, Variability, and Accretion~Dynamics

Pablo Reig

Be/X-ray binaries constitute the largest and most diverse subgroup of neutron star high-mass X-ray binaries. These systems feature a rapidly rotating Be star surrounded by a circumstellar decretion disk that serves as the primary reservoir of accreted matter onto a strongly magnetized neutron star. While a few Be/X-ray binaries remain persistently active, the majority manifest as hard X-ray transient sources, becoming detectable only during X-ray outbursts. This review synthesizes current unders…

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astro-ph.GA

Molecular gas hidden in plain sight in the early Universe

Pasquier Noterdaeme, Jens-Kristian Krogager, Sergei Balashev

We report the discovery of an extreme intervening molecular absorber at zabs = 4.1 towards the z = 4.7 quasar SDSS J080023.02+305101.22 revealed through strong H2 absorption that had remained unnoticed in archival data for about two decades. The system, which we analysed with new VLT/X-shooter observations, has a metallicity of about one-fifth the solar value, in line with the moderate dust reddening AV~0.06 mag. More strikingly, it exhibits the highest molecular fraction, fH2 = 2N(H2)/(2N(H2) +…

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astro-ph.HEastro-ph.GA

A Type Ia Supernova Candidate at $z\sim4.3$: A Transient Interloper in the Search for $z\sim14$ Galaxies

Seiji Toshikage, Takahiro Morishita, Masaomi Tanaka, Kazumi Kashiyama, Charlotte A. Mason, Andrew J. Bunker, Matthew J. Hayes, George Helou et al.

The James Webb Space Telescope (JWST) is opening a new window into the distant Universe by discovering galaxies and transients in the early Universe. We investigate a high-redshift transient candidate, beacon_1420-5253_4770. This object was initially identified as a high-redshift galaxy candidate at $z\sim14$. However, the source was not detected in epochs before and after the detection epoch, suggesting that the object is a transient source rather than a persistent galaxy. We classify the sourc…

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astro-ph.SR

Influence of local and global solar magnetic fields on medium-term forecasting of the number and parameters of coronal mass ejections

Irina A. Bilenko

A study of cyclic variations in the number and parameters of coronal mass ejections (CMEs) in cycles 23-25 demonstrates differences in the behavior of strong and weak CMEs. Strong CMEs, unlike weak CMEs, follow the cyclic evolution of active regions. A method for separately predicting strong and weak CMEs is proposed. Based on global magnetic field (GMF) parameters, the timing of the minima of cycles 26 and 27 (CR~2375$\pm5$ and CR~2526$\pm5$), the duration of cycle 26 (151~CRs or 11.2838 years)…

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gr-qcastro-ph.GA

Accretion of multipolar massive complex scalar field packets by a Schwarzschild black hole

Flavio Rosales-Infante, Ivan Alvarez-Rios, Francisco S. Guzman

We study the finite-time accretion of complex massive scalar wave packets by a Schwarzschild black hole in the test-field regime, with parameters motivated by ultralight fuzzy dark matter around supermassive black holes. Our goal is to determine how the scalar content of a localized configuration is redistributed after interacting with the black hole, and which spectral and multipolar components are more efficiently absorbed. We decompose the Klein--Gordon field into independent multipolar secto…

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astro-ph.SR

Forward Modeling of the $δ$ Sct Star V1790 Ori: $Δν$, $Ω$, Resolution and Non-adiabatic Effects

Xiaoya Sun, Antonio García Hernández, Zhaoyu Zuo, Juan Carlos Suárez, Yifan Wang, Ruixuan Tang, Giovanni M. Mirouh, Taozhi Yang et al.

We investigate the role of large separation, rotational correction order, structural resolution, and non-adiabatic effects in modelling the rotating $δ$ Scuti star V1790 Ori. From TESS data, we extract 69 frequencies and determine $Δν\simeq 82$ $μ$Hz. Rotating MESA models are computed at low and high resolution; their pulsation frequencies are calculated with GYRE (adiabatic/non-adiabatic, first-order rotation) and FILOU (adiabatic, second-order rotation). Using $Δν$ as a structural constraint i…

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astro-ph.GA

Bright Galaxies at Cosmic Dawn: A Cloud-Scale Star Formation Model Unifying Variable SFE, IMFs, and Stochasticity

Elie Cueto, Anne Hutter

To investigate the origins of the high abundance of UV-bright galaxies at z > 10, we present a new semi-analytic model that bridges the gap between small-scale star formation physics and large-scale galaxy evolution by explicitly tracking discrete star-forming clouds within smoothly evolving dark matter potentials. Unlike conventional semi-analytic models, our approach naturally captures the stochasticity of star formation, allowing us to isolate how cloud properties, star formation efficiencies…

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astro-ph.SR

KIC 6464285: A Solar-type Eclipsing Binary in a Hierarchical Triple System with Quasi-periodic Out-of-eclipse Modulations

Fang-Bin Meng, Li-Ying Zhu, Sheng-Bang Qian, Ildar Asfandiyarov, Azizbek Matekov, Jaqsiliq Baltamuratov, Wen-Ping Liao, A-Li Luo et al.

We present the first detailed analysis of the solar-type triple system KIC 6464285. Combining long-term, high-precision photometry from Kepler, TESS, and ZTF with low-resolution spectra from LAMOST and near-infrared high-resolution spectra from SDSS/APOGEE, we performed a joint analysis of the light curves, eclipse timing variations (ETVs), and radial velocities. Spectroscopic analysis reveals the system to be triple-lined, with the inner binary's primary being a G-type main-sequence star and a…

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astro-ph.HE

Searching for $γ$-ray emission from a bona fide Compact Symmetric Object sample: a $γ$-ray signal near GB6 J0906+4124

Ying-Ying Gan, Kai Wang, Ji-Shun Lian, Run-Meng Wang

As a particular subclass of active galactic nuclei (AGNs), compact symmetric objects (CSOs) have attracted significant attention due to potential role as young AGNs. Several $γ$-ray emitting CSOs have been detected with Fermi Large Area Telescope (Fermi-LAT), which motivates further searches for more $γ$-ray emitting CSOs. We perform a systematic search for $γ$-ray emission from a bona fide CSO sample using 16 yr Fermi-LAT observation data. No significant $γ$-ray signal is found to be firmly ass…

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astro-ph.IM

Enhanced Astrometry of the Rapid ASKAP Continuum Survey: Mid and High Frequency Epochs

Akhil Jaini, Adam T. Deller, Yuanming Wang, Emil Lenc, Stefan W. Duschene, Marcin Glowacki

Accurate radio astrometry is essential for reliable cross-identification of sources across wavelengths, precision localisation of transient events, and the construction of stable all-sky reference catalogues. In this work we extend our astrometric correction framework for the Rapid ASKAP Continuum Survey (RACS) to its mid- and high-frequency epochs (RACS-Mid1 and RACS-High1), building on our previous corrections to the low-frequency surveys. Using a hierarchical crossmatching strategy with high-…

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astro-ph.HEastro-ph.GA

Semi-Analytical Model for the Evolution of Stellar Binaries in the Empty Loss Cone of Massive Black Holes

Samuel McGuire, Evgeni Grishin, Ilya Mandel, Yuri Levin

Binary star systems orbiting close to a supermassive black hole (SMBH) evolve through encounters with other stars, the SMBH's tidal forces, and the binary's internal dynamics, including general relativistic precession and tides. Many are driven onto highly eccentric inner binary orbits, potentially leading to stellar mergers; other possible outcomes include hypervelocity star ejections or tidal disruption events. We study the evolution of binaries in the empty loss cone regime, where the outer o…

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astro-ph.HEastro-ph.SR

The XMM-Newton Line Emission Analysis Program (X-LEAP) III: Earth's Magnetospheric X-ray Emission Revealed by 22-Year XMM-Newton Observations

Zeyang Pan, Zhijie Qu, Yuqi Gong, Tianran Sun, Joel N. Bregman, Yingjie Zhang, Li Ji, Jifeng Liu et al.

The magnetosphere, protecting the Earth from intense solar activity, is also shaped by the solar wind, while its structure is still uncertain in observation. In this study, we map the X-ray emission in the magnetosphere, which is induced by the charge exchange between the highly-ionized solar wind and the neutral gas around the Earth, known as the magnetospheric solar wind charge exchange (SWCX). In particular, we extract the magnetospheric SWCX in the O VII line emission data adopted from the X…

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astro-ph.GAastro-ph.SR

Estimating stellar metallicities from Gaia DR3 XP data using LAMOST DR10

Divyansh Srivastava, Andrzej Niedzielski, Rodolfo Smiljanic

Gaia DR3 provides astrophysical parameters for hundreds of millions of stars, but the metallicities [M/H] from its GSP-Phot module suffer from systematic biases. We estimate stellar metallicities from Gaia DR3 data using the homogeneous spectroscopic iron abundances [Fe/H] of LAMOST DR10 as training labels. We cross-matched LAMOST DR10 with Gaia DR3 and trained a gradient-boosted decision-tree regressor (XGBoost) on 1.20 million AFGK stars using only Gaia-derived inputs and proxies. We validated…

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astro-ph.HEhep-ph

Universal scaling between magnetar field and initial spin period for short gamma ray bursts

Qin-Mei Li, Qi-Bin Sun, Sheng-Bang Qian, Li-Yin Zhu, Fu-Xing Li, Si-Yuan Zhu, Ming Lian, Jing Li et al.

The $B_p$--$P_0$ correlation serves as a critical probe of magnetar engine physics. Although this scaling relation has been firmly established for long gamma-ray bursts (lGRBs), systematic investigations for short GRBs (sGRBs) remain absent, leaving the physical differences between the two populations poorly constrained. Here we analyze 33 Swift sGRBs exhibiting prominent X-ray plateaus from newborn millisecond magnetar spin-down, and derive their initial spin period $P_0$ and polar magnetic fie…

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astro-ph.GAastro-ph.COgr-qc

Resolving Galactic and Cluster Dynamics Without Dark Matter: Tsallis Entropy as the Unique Foundation of Emergent Gravity

S. Shamari, A. Sheykhi

While modified entropy models-such as Barrow, Tsallis, Kaniadakis,Power-law, Logarithmic, and Rényi entropies-have been widely explored in cosmological contexts, their implications on galactic scales remain largely untested. These generalizations of the Bekenstein-Hawking entropy encode quantum gravitational, nonextensive, or fractal spacetime effects and can alter the gravitational entropy-area relation. In this paper, we demonstrate that the entropic force framework, when applied to galactic r…

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astro-ph.EP

Azimuthal molecular variations in the AB Aur planet-forming disk

Haochang Jiang, Dmitry Semenov, Myriam Benisty, Vincent Piétu, Thomas Henning, Pablo Rivière-Marichalar, Lucas M. Stapper, Edwige Chapillon et al.

Late infall episodes are emerging as an important driver of disk evolution. Observed as filamentary streamers in molecular lines and scattered light, such accretion perturbs disk structures, yet its chemical consequences remain unconstrained. We present NOEMA 1.2 mm observations of AB Aur, a structured young Herbig disk showing evidence for ongoing infall and planet formation. We detect azimuthal chemical diversity: SO emission is enhanced in the northern disk near the inferred streamer-disk int…

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