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Research Trends

Latest preprints in space engineering and astrophysics.

astro-ph.IMastro-ph.EPphysics.opticsphysics.space-ph

Mechanisms of Electrostatic Charge Formation and Retention in Lunar Regolith

Minhyeok Kim, Hyun Jung Kim, Sang H. Choi, Ashley Daeun Jung

As the Artemis program advances toward the lunar south pole and permanently shadowed regions (PSRs), understanding lunar charging is increasingly important for protecting astronauts, robotic systems, instruments, and infrastructure. Persistent darkness, cryogenic temperatures, low regolith conductivity, and long charge-relaxation times may allow energetic-particle-induced charge to accumulate beneath the surface. This Technical Memorandum addresses a key unresolved question: how is electrostatic…

astro-ph.GA

A Direct DESI--SDSS Two-Fibre Test of Aperture Bias in Optical Emission-Line Diagnostics

Shihong Liu, Yu Rong

Fixed angular apertures sample different physical regions of nearby galaxies and can therefore bias optical emission-line diagnostics. We use 20,545 high-confidence emission-line galaxies observed by both the Dark Energy Spectroscopic Instrument (DESI) and the Sloan Digital Sky Survey (SDSS) as a two-fibre experiment, in which the DESI 1.5 arcsec fibre is nested within the SDSS 3 arcsec fibre. To isolate aperture effects from line-measurement systematics, we refit every spectrum using the same e…

astro-ph.GA

A Direct DESI--SDSS Two-Fibre Test of Aperture Bias in Optical Emission-Line Diagnostics

Shihong Liu, Yu Rong

Fixed angular apertures sample different physical regions of nearby galaxies and can therefore bias optical emission-line diagnostics. We use 20,545 high-confidence emission-line galaxies observed by both the Dark Energy Spectroscopic Instrument (DESI) and the Sloan Digital Sky Survey (SDSS) as a two-fibre experiment, in which the DESI 1.5 arcsec fibre is nested within the SDSS 3 arcsec fibre. To isolate aperture effects from line-measurement systematics, we refit every spectrum using the same e…

astro-ph.IMastro-ph.GA

DustRover: A Python Package for Modelling Dust Extinction Curves (Phase I)

Amir E. Bazkiaei, Tayyaba Zafar, Nuria P. F. Lorente, Anilkumar Mailvaganam, Arihant Raidani

We introduce DustRover, an open-source Python package designed to model dust extinction curves using multi-wavelength regimes. DustRover supports optical/infrared spectroscopy, broadband photometry, and X-ray data within a unified framework, enabling robust analysis of dust extinction curves in distant galaxies. The software features a modular architecture that strictly decouples data management, dust models, and Markov Chain Monte Carlo (MCMC) based statistical fitting. The package is highly us…

astro-ph.IMastro-ph.GA

PERRY: A Human-in-the-Loop GUI for Precision Alignment of MUSE Data

Amir E. Bazkiaei, Brent Miszalski, Jesse van de Sande, Nuria P. F. Lorente, Simon O'Toole, Kate Sheng

The Multi Unit Spectroscopic Explorer (MUSE) on the Very Large Telescope produces high-dimensional data-cubes where even minor astrometric misalignments between multiple exposures can introduce severe artifacts and compromise data quality. While automated pipelines provide a crucial baseline, subtle offsets require human intervention. To address this, we introduce PERRY, an interactive, Python-based Graphical User Interface (GUI) explicitly designed for the visual inspection and manual fine-tuni…

stat.MLastro-ph.COastro-ph.IMcs.AIcs.LG

Recovering Weak Signals with Normalizing Flows

Sarod Yatawatta

In many scientific disciplines, weak signals of interest are obscured by dominant nuisance signals that are several orders of magnitude stronger. Recovering these weak signals requires subtracting the dominant ones; however, this calibration process inherently distorts or partially suppresses the underlying signal of interest. To address this problem, we propose the use of normalizing flow models to reconstruct calibration-affected weak signals. By leveraging the statistical invariance of the ta…

astro-ph.HEgr-qcnucl-th

Detectability of bulk viscosity effects on post-merger gravitational wave signals from binary neutron star mergers

Zhenyu Zhu, Michail Chabanov, Richard O'Shaughnessy

We investigate bulk viscosity (BV) effects on post-merger gravitational wave (PMGW) signals from binary neutron star (BNS) mergers and their detectability using realistic equation of state (EoS) posteriors constrained by recent progress in gravitational-wave (GW) and X-ray observations, as well as neutron skin thickness measurements. A linear fitting formula based on recent BNS simulations with BV is used to estimate the peak frequency shift of the PMGWs caused by BV effects. Subsequently, we ev…

astro-ph.HEgr-qcnucl-th

Constraining the Equation of State of Neutron Stars with third-generation Gravitational Wave detectors

Zhenyu Zhu, Richard O'Shaughnessy

We investigated the impact of the number of binary neutron star merger events and neutron star (NS) mass distributions on constraining the equation of state (EoS), tidal deformability and radius of NSs, as well as the nuclear parameters, using binary neutron star inspiral gravitational wave signals with third-generation detectors. We generate simulated gravitational wave signals and compute the Fisher information matrix for each event after the number of events and mass distribution models are g…

astro-ph.SRastro-ph.HE

IPHAS J190812.63+045728.1: A deeply eclipsing, X-ray bright cataclysmic variable with frequent outbursts

Raimundo Lopes de Oliveira, Albert Bruch, Koji Mukai, A. S. de Araujo, Guilherme P. Guimarães, Ted Leandro de Almeida

We present a multi-wavelength characterization of IPHAS J190812.63+045728.1. Independently discovered by us after being serendipitously observed by XMM-Newton, followed up with optical photometry with SPARC4/OPD and spectroscopy with GMOS/Gemini South, and exploring archival TESS and ZTF observations, we reveal the system to be an eclipsing accreting white dwarf (WD) system with an orbital period of 5.073 h. The deep optical and flat-bottomed X-ray eclipses completely occult the WD and the accre…

astro-ph.SR

Coordinated Coronagraphic Observations from Proba-3 and Aditya-L1: Investigating CME Energetics in the Inner Corona

Anjali Agarwal, Wageesh Mishra, R. Ramesh, V. Muthu Priyal, A. N. Zhukov, Jagdev Singh, Nat Gopalswamy, Soumyaranjan Khuntia et al.

Constraining the plasma properties and energetics of coronal mass ejections (CMEs) in the inner corona is essential for understanding their early evolution, yet remains challenging because of limited observations. We investigate the mass and density evolution, and energy partitioning of two CMEs observed on 2025 September 14 and 16, and assess the potential of coordinated Proba-3/ASPIICS and Aditya-L1/VELC observations to constrain CME energetics in the low corona. We present the first coordinat…

astro-ph.GAcs.CVcs.LG

Deep learning from the crowd Fundamentals of morphological galaxy classification

Luis Enrique Sucar, Carlos del Burgo, Jonathan Serrano-Pérez

Aims. The objective of this work is to adapt a deep neural network model to perform galaxy morphological classification trained from crowd annotations, considering the training scheme, the agreement between the annotators, and the hierarchy. Methods. We use Galaxy Zoo 1 as our experimental testbed and trained a convolutional neural network (CNN) for the automatic classification of galaxies' morphologies. We analyze the impact of the following aspects on the classification accuracy and training e…

astro-ph.GAastro-ph.SR

Interstellar Complex Organic Molecules and Molecular Outflows in NGC 1333 IRAS 4B and 4B' Observed Using NOEMA

C. C. Sarver, M. M. Giese, D. C. Lis, S. L. Widicus Weaver

We present interferometric observations with the Northern Extended Millimeter Array (NOEMA) of NGC 1333 IRAS 4B and 4B', two young stellar objects (YSOs) within the Perseus molecular cloud. YSOs, especially Class 0 protostars, are rich in gas-phase interstellar complex organic molecules (iCOMs), but relatively little is known about the spatial distribution of these important prebiotic molecules. Various molecules were imaged within IRAS 4B and the surrounding area in the 145 GHz spectral range,…

astro-ph.GAastro-ph.SR

Interstellar Complex Organic Molecules and Molecular Outflows in NGC 1333 IRAS 4B and 4B' Observed Using NOEMA

C. C. Sarver, M. M. Giese, D. C. Lis, S. L. Widicus Weaver

We present interferometric observations with the Northern Extended Millimeter Array (NOEMA) of NGC 1333 IRAS 4B and 4B', two young stellar objects (YSOs) within the Perseus molecular cloud. YSOs, especially Class 0 protostars, are rich in gas-phase interstellar complex organic molecules (iCOMs), but relatively little is known about the spatial distribution of these important prebiotic molecules. Various molecules were imaged within IRAS 4B and the surrounding area in the 145 GHz spectral range,…

astro-ph.GAastro-ph.HE

Connecting the little dots in polarized light

Piero Madau, Roberto Maiolino, Francesco D'Eugenio

Recent observations of the local Little Red Dot (LRD) analog SDSS~J1025+1402 have revealed that the optical continuum is polarized at the ~1.5% level, while broad Halpha has lower polarization (~0.7%) and a different polarization angle. We explain these properties in a scenario in which LRDs are dust-obscured Little Blue Dots (LBDs) viewed at high inclination and powered by super-Eddington accretion. In this framework, electron scattering in the geometrically thick inner accretion flow produces…

gr-qcastro-ph.IM

Alternative neural-network follow-up for all-sky FrequencyHough in continuous gravitational-wave searches

Martina Di Cesare, Pia Astone, Rosario De Rosa, David Keitel, Cristiano Palomba, Marco Serra

Continuous gravitational waves are long-lived signals emitted by spinning neutron stars (NSs) or boson clouds around black holes. While the Milky Way is expected to host $\mathrm{O}(10^{8}-10^{9})$ NSs, only $\mathrm{O}(10^{3})$ are currently identified through electromagnetic observations. This large observational gap motivates searches based on alternative messengers. In particular, all-sky searches for continuous gravitational waves (GWs) offer a unique opportunity to detect NSs that are elec…

astro-ph.HEastro-ph.SR

The First Multi-Messenger Nova: External Shocks, TeV Photons, and Neutrinos in the Next Eruption of T CrB

E. Aydi, P. Craig, K. V. Sokolovsky, L. Chomiuk, C. C. Cheung, L. Izzo, J. D. Linford, B. D. Metzger et al.

T Coronae Borealis is the most compelling anticipated Galactic recurrent nova and one of the best opportunities to test whether nova eruptions can become genuine multi-messenger transients. Recent observational work on classical novae has shown that the GeV $γ$-ray luminosity correlates strongly with the differential velocity between interacting outflows, suggesting that shock power depends strongly on velocity contrast. We apply this empirical framework to T CrB and compare it with the 2021 eru…

physics.pop-phastro-ph.IMphysics.opticsphysics.space-ph

Project Setu: 3D Multi-Physics Design and Spaceflight-Validated Framework for a 0.20c Relativistic Lightsail

Prashant Suresh Kamble

Deep-space exploration beyond the solar system requires eliminating chemical propellant mass penalties to achieve relativistic flight velocities (0.166c at 180 s, reaching the mission target of 0.20c at 227 s). This study presents a 3D multi-physics numerical framework for a 4.0-meter circular lightsail propelled by a 100 GW ground laser array, coupling 3D Maxwell FDTD wave optics, non-linear membrane mechanics, and Stefan-Boltzmann thermal radiation in ANSYS Mechanical APDL and Ansys Lumerical.…

physics.pop-phastro-ph.IMphysics.opticsphysics.space-ph

Project Setu: 3D Multi-Physics Design and Scaled Structural Analysis for a Relativistic Lightsail Architecture

Prashant Suresh Kamble

Deep-space exploration beyond the solar system requires eliminating chemical propellant mass penalties to achieve relativistic flight velocities (0.166c at 180 s, reaching the mission target of 0.20c at 227 s). This study presents a 3D multi-physics numerical framework for a 4.0-meter circular lightsail propelled by a 100 GW ground laser array, coupling 3D Maxwell FDTD wave optics, non-linear membrane mechanics, and Stefan-Boltzmann thermal radiation in ANSYS Mechanical APDL and Ansys Lumerical.…

astro-ph.HEgr-qc

An HLLD Implementation for General Relativistic Magnetohydrodynamics in AthenaK

Jacob Fields, George N. Wong, James M. Stone

We present an implementation of an HLLD approximate Riemann solver for the AthenaK astrophysics code with support for full general relativistic magnetohydrodynamics via a tetrad frame transformation. Our implementation uses an initial guess for the HLLD iterative solve which eliminates the need for an additional conserved-to-primitive inversion, which greatly accelerates performance without affecting accuracy. Additionally, by coupling the method with a first-order flux correction, we are able t…

astro-ph.EPastro-ph.GA

Shaving the Outskirts of Planetary Systems Probed by Roman via Stellar Flybys

Donald Liveoak, Tim Hallatt, Sarah Millholland

The recently launched Nancy Grace Roman Space Telescope (\textit{Roman}) will soon begin observations that promise to revolutionize our understanding of exoplanet demographics. \textit{Roman}'s Galactic Bulge Time-Domain Survey (GBTDS) will observe the Galactic Bulge via transit and microlensing techniques, providing a unique opportunity to study hot Jupiters as well as long-period/free-floating exoplanets in a dense and kinematically hot stellar environment. In this Letter, we quantify how repe…

astro-ph.GA

FAST Observations of Filamentary and Compact H I Structure in a Magellanic Stream IV Field

Yuxin Xiao, Qingzheng Yu, Taotao Fang, Di Li, Shulan Yan, Shuo Zhang

The Magellanic Stream (MS) is believed to have formed from gas removed from the Large and Small Magellanic Clouds through tidal forces and hydrodynamic interactions with the Milky Way's gaseous halo. It provides an important laboratory for studying how stripped gas fragments, mixes, and evolves in a circumgalactic environment. In this work, we present HI observations of a $3.8^\circ\times2.2^\circ$ field in the MS IV region, using the data from the Commensal Radio Astronomy FasT Survey (CRAFTS).…

astro-ph.HEgr-qc

The accuracy of merger times in hierarchical black hole triples

Giulia Fumagalli, Alejandro Vigna-Gómez

Orbit-averaged equations are widely used to model the gravitational-wave-driven evolution of compact binaries. Their validity relies on the radiation-reaction timescale being much longer than the orbital period, an assumption that can break down for highly eccentric systems. In this work, we investigate the impact of orbit averaging on merger-time estimates by comparing orbit-averaged and non-orbit-averaged prescriptions. We apply our analysis to two different astrophysically motivated populatio…

gr-qcastro-ph.HE

Physics-based phenomenological modeling of binary black hole hierarchical formation 1: Synthetic universes from globular cluster simulations for GWTC

R. O'Shaughnessy, R. Mechum, M. Qazalbash, Z. Rosenberg, M. Zeeshan

We iteratively model the GWTC-5.0 binary-black-hole census with three components. First, a physically normalized population from Rapster globular-cluster simulations spans cluster mass, metallicity, formation redshift, compactness, and natal black-hole spin. Hierarchical mergers reproduce higher-mass events and their larger effective-spin dispersion, provided black holes are born with zero natal spin. Second, a phenomenological field (isolated-binary) channel supplies the low-mass, preferentiall…

gr-qcastro-ph.GAastro-ph.IMhep-ph

Self-supervised reconstruction of transients in data from space-borne gravitational-wave detectors

Yuxiang Xu, Minghui Du, Bo Liang, Zihao Xiao, Tianyu Zhao, Peng Xu

Space-based gravitational-wave (GW) data may contain transient signals whose waveform morphologies are not known in advance. Extracting these signals is important for characterizing new sources and mitigating instrumental anomalies. However, existing deep neural network (DNN)-based extraction approaches rely on clean training targets and waveform-class-specific examples, which may limit their applicability when the transient morphology is not specified in advance. This work develops a Noise2Nois…

astro-ph.SRastro-ph.HE

Magnetically Confined Mountains on Accreting White Dwarfs

Pedro H. B. Rossetto, Manoel F. Sousa, Diego A. Falceta-Gonçalves

The hydromagnetic structure of magnetically confined mountains on accreting white dwarfs is computed, alongside the effects of accretion on the reduction of the star's magnetic field. The equilibrium structure of the mountain is obtained by numerically solving the Grad-Shafranov equation with a self-consistent scheme that enforces magnetic flux freezing. For characteristic system parameters, it is shown that magnetic field lines are significantly deformed and dragged equatorwards by mountains wi…

astro-ph.SRastro-ph.GA

A Uniform Census of Variable Stars in M101 Based on HST/ACS Photometry

Jiyu Wang, Xiaodian Chen, Pinjian Chen, Jianxing Zhang, Shu Wang, Licai Deng

We present a homogeneous HST/ACS F555W/F814W time-series census of variable stars in two M101 disk fields, using a uniform multi-band reduction and reproducible variable-selection workflow for nearby SN-host galaxies. Supplementary archival F555W epochs are used only to refine selected long-period solutions. Candidates are selected with Lomb-Scargle period searches, Fourier light-curve modeling, two-band consistency statistics, artificial-star-test photometric corrections, and mode-aware Cepheid…

eess.SPphysics.space-ph

Wideband HF Skywave Propagation: A Review with Link Modeling Corroborated by Propagation Data

Eric Weber, Ted Nowak, Joseph Berg, Nader Behdad

The high-frequency (HF) band, ranging from 3 to 30 MHz, is widely used in a number of applications such as beyond-line-of-sight (BLOS) communications and over-the-horizon radar systems. The long-range propagation characteristics of the HF band rely on the Earth's ionosphere as a refracting medium to establish BLOS wireless links. However, traditional HF communications links often use channels with narrow bandwidths (typically 3 kHz), which limits the amount of data that can be transmitted. In th…

nucl-thastro-ph.HE

Hadron resonance gas with density-dependent interactions for neutron stars and heavy-ion collisions

Volodymyr Vovchenko, Volodymyr Kuznietsov, Tripp Moss

We present a density-dependent generalization of the van der Waals hadron resonance gas model (DD-HRG) for describing both the hot hadronic matter created in heavy-ion collisions and the cold, dense matter inside neutron stars. Non-resonant interactions are incorporated through a generalized excluded-volume prescription with a density-dependent available-volume fraction, supplemented by an arbitrary density-dependent mean field. With isospin-dependent interaction parameters constrained by empiri…

astro-ph.HE

A Possible X-ray and Gamma-ray Quasi-Periodic Oscillation in GRB 241030A

Noel Klingler, Cecilia Chirenti, M. Coleman Miller, Amy Lien, Simone Dichiara

Quasiperiodic oscillations (QPOs) in gamma-ray intensity have been reported from a few gamma-ray bursts. These QPOs could be related to fundamental frequencies in the sources, which would lead to new insights about these systems. Here we report on our analysis of GRB~241030A, a several-minute-long burst with $\sim 10$ gamma-ray flares that have approximate periodicities at f ~ 0.04 Hz and f ~ 0.08 Hz. This quasi-periodicity is seen in X-rays with the Swift X-Ray Telescope (XRT) as well as in gam…

astro-ph.SRastro-ph.GA

Unresolved triple systems in the aged open cluster Trumpler 19: Discovery, confirmation, and implications

D. Minniti, R. K. Saito, V. D. Ivanov, C. O. Obasi, P. W. Lucas, J. G. Fernández-Trincado, J. Alonso-García, E. R. Garro et al.

It is difficult to identify unresolved triple and higher-order systems beyond the solar vicinity. Star clusters yield controlled environments with known physical parameters, providing a way to explore homogeneous stellar samples. Combining modern optical and near-IR surveys, our main goal is to explore the region of the color-magnitude diagrams located above the sequence of equal-mass binaries, which is inhabited by unresolved triple and quadruple systems. Specifically, here we aim to discover a…