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Research Trends

Latest preprints in space engineering and astrophysics.

physics.med-phastro-ph.IMphysics.optics

Retinal hazards and glare from space mirrors

Salvador Bará

Projects of orbital mirrors reflecting sunlight towards Earth raise reasonable concerns regarding photochemical and thermal retinal hazards and detrimental effects on visual performance (disability glare). This paper addresses these issues based on some current eye safety and glare standards. Telescopic observations of single mirrors appear to pose a significant risk of photochemical retinal hazard. The risk is higher for vulnerable populations. Unaided eye viewing of a mirror keeps the retinal…

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astro-ph.HE

WFST Follow-up of S251112cm: Searching for an Optical Counterpart to a Subsolar-mass Compact-binary Merger Candidate

Zhengyan Liu, Zelin Xu, Ji-an Jiang, Wen Zhao, Zhiping Jin, Zigao Dai, Dezheng Meng, Yefei Yuan et al.

Electromagnetic counterparts to gravitational-wave (GW) sources probe the properties, environments, and evolution of compact-object mergers. S251112cm belongs to an emerging class of GW candidates with possible subsolar-mass components. We present an optical counterpart search for S251112cm with the Wide Field Survey Telescope (WFST). The observations began 20.2 hr after the GW trigger and continued for three nights, covering approximately $780~\mathrm{deg}^{2}$ and $51\%$ of the localization pr…

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astro-ph.IM

The GOTO Telescope Control System

Martin J. Dyer, Vik S. Dhillon, Stuart Littlefair, Kendall Ackley, Sergey Belkin, Lisa Kelsey, Tom Killestein, Amit Kumar et al.

The Gravitational-wave Optical Transient Observer (GOTO) operates a network of robotic, wide-field survey telescopes searching for optical transients to gravitational-wave signals and other astronomical events. Since 2023, the network has comprised two antipodal sites in the Canary Islands and Australia, each hosting two independent robotic mounts. The GOTO Telescope Control System (G-TeCS) is a custom Python software package that manages all operational aspects of the network; from alert proces…

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astro-ph.EP

Characterisation of chaos in meteoroid streams. Application to the Taurids

Ariane Courtot, Melaine Saillenfest, Marc Fouchard, Jérémie Vaubaillon

Aims. We explore the dynamics of the Northern and Southern Taurid meteoroid streams to identify major mechanisms structuring the evolution of the streams. Methods. We use chaos maps and numerical simulations to explore the dynamics of the streams. We also perform some semi-analytical analysis to confirm the mechanisms we identified in the maps. Results. We show how Northern Taurids are structured by the von Zeipel-Lidov-Kozai mechanism and how it interacts with several mean-motion resonances wit…

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astro-ph.GA

Low Star Formation Efficiency in M31: Evidence for a Deficit of Bound Gas

Fangyuan Deng, Sihan Jiao, Hauyu Baobab Liu, Jingwen Wu, Henrik Beuther, Fanyi Meng, Caroline Gieser, Yuxin Lin et al.

The Andromeda galaxy (M31) exhibits a systematically low star formation efficiency (SFE) compared to other star-forming galaxies. Star formation is thought to be regulated by the mass of gravitationally bound gas. To investigate whether the low SFE in M31 originates from a scarcity of such bound gas, we analyze the dynamical state of its giant molecular cloud (GMC) population by estimating their virial parameters ($α_{\rm vir}$). Using a JCMT-SCUBA2 850 micron dust-continuum GMC catalog as the p…

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astro-ph.HE

The unidentified PeV source LHAASO J2108+5157: A microquasar remnant?

Josep Martí, Pedro L. Luque-Escamilla, Leandro Abaroa, Gustavo E. Romero, Valentí Bosch-Ramon, Josep M. Paredes, Cintia S. Peri

Context. LHAASO~J2108+5157 is one of the most intriguing Galactic ultra-high-energy $γ$-ray sources. It is detected up to hundreds of TeV but lacks a clear counterpart at lower frequencies. Fermi-LAT observations have revealed a compact GeV source spatially coincident with the PeV emission, while VERITAS and LST-1 impose stringent upper limits in the intermediate TeV band, producing a pronounced spectral suppression between the GeV and TeV domains. Aims. We investigate a time-dependent hadronic…

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astro-ph.GA

Self-interacting dark matter delays bar growth in an isolated gas-rich galactic disk: torque-resolved numerical evidence

Dong-Biao kang

We investigate how a dynamically responsive gas disk changes the influence of self-interacting dark matter (SIDM) on stellar-bar formation. In an isolated Milky-Way-mass galaxy with fixed total baryonic mass, the gas-rich collisionless (CDM) model develops a persistent bar at $1.96\,\Gyr$, whereas the matched SIDM model with $\sigmam=1\,\mathrm{cm^2\,g^{-1}}$ does so at $2.69\,\Gyr$. The final stellar $m=2$ amplitude is 0.437 in CDM and 0.340 in SIDM, a 22 per cent suppression; the corresponding…

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gr-qcastro-ph.IM

Searching for gravitational wave echo with group equivariant neural posterior estimation

Jian-Wei Luo, Yun-Song Piao

Current methods for the gravitational-wave (GW) echo searches generally require substantial computational time and resources. Recent advances in group equivariant neural posterior estimation (GNPE) have demonstrated the potential to substantially accelerate posterior inference. In this work, we adopt this framework and train a GNPE model to perform echo searches, significantly improving computational efficiency while maintaining comparable inference accuracy. We apply it to the O4a events and fi…

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astro-ph.EPastro-ph.IM

Bridging magnetothermal winds and photoevaporation to model discs dispersal

Giovanni Picogna, Barbara Ercolano

Protoplanetary disc dispersal is driven by two processes usually modelled separately: photoevaporative and magnetohydrodynamic (MHD) disc winds. Global simulations indicate that in the inner disc these are not distinct outflows but a single magnetothermal wind. We assemble a closed-form, two-phase model that respects it. A single-field-line wind, whose base is fixed by the irradiated temperature and penetration column, supplies the launch and feeds a secular evolution, with photoevaporation conv…

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astro-ph.EPastro-ph.IM

Bridging magnetothermal winds and photoevaporation to model discs dispersal

Giovanni Picogna, Barbara Ercolano

Protoplanetary disc dispersal is driven by two processes usually modelled separately: photoevaporative and magnetohydrodynamic (MHD) disc winds. Global simulations indicate that in the inner disc these are not distinct outflows but a single magnetothermal wind. We assemble a closed-form, two-phase model that respects it. A single-field-line wind, whose base is fixed by the irradiated temperature and penetration column, supplies the launch and feeds a secular evolution, with photoevaporation conv…

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astro-ph.GA

The Delegate Survey: KOALA/AAOmega-IFU spectroscopy of three nearby dwarf galaxies

Kyungdo Ko, Helmut Jerjen, Sarah M. Sweet, Ángel R. López-Sánchez, Simon Deeley, Caroline Foster, Holger Baumgardt, Pratyush Kumar Das et al.

Assessing the cosmological typicality of the Local Group is crucial for establishing whether its dwarf galaxy population is representative. To this end, the Delegate Survey targets dwarf galaxies in Local Group analogues for systematic comparison. As a pilot study for the Delegate Survey, we obtained integral-field spectra of three dwarf galaxies, GAMA 79098, GAMA 569709, and HIPASS J1159-19 S2, in two nearby galaxy groups using the KOALA instrument on the AAT. The galaxies were mapped at a spat…

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astro-ph.IM

cosmokdtree: a flexible OpenMP-parallelized k-d tree for computational astrophysics applications

Óscar Monllor-Berbegal, David Vallés-Pérez, Susana Planelles, Vicent Quilis

Modern numerical astrophysics applications present a common demand for efficient spatial querying techniques, such as neighbor searches or density estimations over billions of resolution elements. To address the growing need for fast and versatile tools tailored to these tasks, we present cosmokdtree, a fast and flexible multi-purpose k-d tree implementation in Fortran, parallelized with OpenMP directives. Our library supports arbitrary dimensionality and spatial distributions, and is designed f…

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astro-ph.SR

Mode Switching in Two Blue Large Amplitude Pulsators observed by OGLE, KMTNet and DREAMS

Hao Ma, Shude Mao, Seung-Lee Kim, Hongjing Yang, Weicheng Zang, Tianjun Gan, Steve Heathcote, Chung-Uk Lee et al.

Blue large-amplitude pulsators (BLAPs) are rare, hot, short-period pulsating stars whose rapid oscillations provide a unique probe of stellar interiors and atmospheres. In this paper, we study two short-period BLAPs in the Galactic bulge, OGLE-BLAP-142 ($P \approx 6.6$ min) and OGLE-BLAP-148 ($P \approx 7.5$ min), by combining light curves from the OGLE, KMTNet, and DREAMS surveys, spanning 17 years with cadences ranging from minutes to hours to days. We perform Generalized Lomb-Scargle periodog…

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hep-phastro-ph.HE

Probing Feebly Interacting Particles with 511 keV Line from Circumstellar Medium of Supernovae

Yu Cheng, Chui-Fan Kong, Yen-Hsun Lin, Meng-Ru Wu, Seokhoon Yun

Core-collapse supernovae (CCSNe) are intense sources of feebly interacting particles (FIPs), whose visible decays beyond the stellar envelope can generate distinct electromagnetic signals. We propose the circumstellar medium (CSM) surrounding the CCSNe progenitor as a new target for 511 keV line searches. FIPs escaping the stellar interior may decay into electron-positron pairs and inject positrons into the CSM, where they slow down and subsequently annihilate, giving rise to a 511 keV line as a…

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astro-ph.HEastro-ph.IM

Toward Autonomous Radio Follow-up of Multi-messenger Transients with RADAR: From Alert Parsing to Inference and Observation Scheduling

Mihael Hategan-Marandiuc, Tanner O'Dwyer, Alessandra Corsi, Eliu Huerta, Zilinghan Li, Ian T. Foster, Kyle Chard, Ryan Chard et al.

Multi-messenger astronomy (MMA), the joint study of cosmic sources through gravitational waves (GWs), electromagnetic (EM) radiation, neutrinos, and cosmic rays, is rapidly reshaping time-domain astrophysics. Realizing the promise of MMA will require coordinating heterogeneous observing resources and automating the chain from alert to analysis to follow-up. RADAR (Radio Afterglow Detection and AI-driven Response) is a federated, privacy-enhancing framework for the radio follow-up of GW events, p…

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astro-ph.HE

Detectability of 100 TeV Gamma Rays from PeV Cosmic Rays Accelerated in the Early Phase of a Supernova Shock Wave

Tomotaka Nishikawa, Tsuyoshi Inoue, Alexandre Marcowith

Galactic cosmic rays (CRs) are thought to be accelerated by diffusive shock acceleration in supernova remnants (SNRs), but observations of SNRs aged ~100-1000 yr suggest maximum CR energies below the PeV level. Recently, Inoue et al. (2021) showed with kinetic-MHD simulations that CRs can be accelerated to ~3 PeV when a blast wave shock propagates through dense circumstellar material (CSM) within tens of days after explosion. Such CSM can be produced by a red-supergiant (RSG) wind with an observ…

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astro-ph.COastro-ph.GA

Void probability function in the Quijote simulations

Snehasish Bhattacharjee

The void probability function (VPF) is the likelihood of finding no tracers (galaxies or dark-matter haloes) within a given volume and is sensitive to the large-scale matter distribution. We investigate the VPF of dark matter haloes and galaxies using the \textsc{Quijote} N-body simulations across a range of cosmological models, including $Λ$CDM and several extensions. We examine its dependence on cosmology, redshift, halo mass, morphology, and sample dilution, and compare the results with theor…

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hep-phastro-ph.HE

Gravitational lensing of neutrinos through the lens of decoherence

Bikash Kumar Acharya, Ujjal Kumar Dey

We propose a new source of neutrino decoherence arising from stochastic gravitational lensing by unresolved mass substructure. Unlike traditional models that treat the lensing potential as smooth and deterministic, we decompose the lensing potential into a smooth component and a stochastic population of compact clumps. The substructure induced fluctuations of the lensing potential generate stochastic corrections to the neutrino time delay, thereby producing random relative phases between differe…

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astro-ph.HEastro-ph.GA

RadioAstron space-VLBI imaging of the jet in M87: II. The parsec-scale structure at 4.8 GHz

Evgeniya V. Kravchenko, Tuomas Savolainen, Alexey S. Nikonov, Ilya N. Pashchenko, Elena E. Nokhrina, Petr A. Voitsik, Leonid I. Gurvits, Yuri Y. Kovalev et al.

We present RadioAstron observations of the M87 jet obtained on 2014 February 4-5 at 4.8 GHz ($λ=6.2$ cm). The correlated signals between the 10-m space antenna and ground-based radio telescopes were detected up to projected baselines of $\thicksim3$\,Earth diameters (0.65~G$λ$). The orientation of the jet downstream of the core shifts northward, consistent with the long-term oscillating trend reported in other studies. An elliptical body mode of the Kelvin-Helmholtz instability can create the ob…

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astro-ph.GA

Galaxy-Galaxy Strong Lensing simulation with the GPU acceleration across surveys and multi-bands

Fucheng Zhong, Ruibiao Luo, Nicola R. Napolitano, Crescenzo Tortora, Valerio Busillo, Rui Li

We present a GPU-accelerated, PyTorch tensor-based simulation framework designed to generate high-fidelity galaxy-galaxy strong lensing images. By integrating synthetic Spectral Energy Distribution (SEDs), the pipeline accurately models the redshift-dependent photometric properties of lens and source galaxies, ensuring physical consistency across multi-band observations. The framework incorporates key observational parameters, including Point Spread Functions (PSF), magnitude limits, and zero po…

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astro-ph.GA

A Detailed GASKAP-HI View of Shells and Loops in the Magellanic Bridge

Shin-Jeong Kim, Antoine Marchal, N. M. McClure-Griffiths, J. R. Dawson, James Dempsey, Helga Dénes, John M. Dickey, Steven J. Gibson et al.

We present 8 pc-scale GASKAP-HI observations of an HI shell (diameter \sim130 pc) associated with the Hαshell DEM171 in the Magellanic Bridge. The Bridge's diffuse, HI-dominated environment, with minimal galactic shearing and fewer overlapping star-forming regions, provides an ideal environment to study cold gas formation driven by stellar feedback. To investigate the HI multi-phase structure and kinematics of the shell, we perform Gaussian decomposition of HI line profiles. We identify cold HI…

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astro-ph.IM

Transitioning from ADS to SciX to Serve 21st Century Astronomy

Jennifer Lynn Bartlett, Suze Kundu, Alberto Accomazzi, Michael J. Kurtz

For decades, the NASA Astrophysics Data System (ADS) has been the foundational digital library for astronomy. As ADS becomes the Science Explorer (SciX), the team prioritizes preserving this trusted experience while increasing their support for space and Earth sciences broadly, without diluting its commitment to astrophysics.

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astro-ph.HE

FRB 20250607A: Weirder Than Fiction

J. C. F. Balzan, A. Bera, C. W. James, B. W. Meyers, A. T. Deller, R. M. Shannon, Z. Wang

We present a detailed analysis of FRB 20250607A, a two-component FRB detected by the CRAFT survey which exhibits several unusual component-dependent properties, including apparent differential DM, circular polarisation, and time-resolved RM, together with a polarisation-angle (PA) swing that persists through the scattering tail. The scattering timescale and scintillation bandwidth are inconsistent with a single thin-screen origin, placing the dominant scattering screen within $\lesssim61$ kpc of…

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astro-ph.IMquant-ph

Progress in quantum telescopes

David R. Gozzard, Fiona H. Panther, Andrew G. White

Classically, the angular resolution of a telescope is limited by its diffraction limit: the ratio of its observing wavelength to its diameter. Developments in quantum information theory over the past decade have uncovered quantum-optimal measurement methods that enable super-resolution imaging beyond the diffraction limit, and many laboratory-scale demonstrations of these methods have been performed over the past decade, culminating in the recent first on-sky demonstration of quantum-enhanced as…

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astro-ph.SRastro-ph.IMcs.AIcs.LG

Physics-Informed Neural Networks for Fast Multilayer Spectral Inversion of Hα 6562.8 A and Ca II 8542.1 A Spectra

Ziyang Zhang, Qin Li, Vasyl B. Yurchyshyn, Kangwoo Yi, Haimin Wang, Wenda Cao, Bo Shen

Strong chromospheric absorption lines such as H$α$ 6562.8 A and Ca II 8542.1 A provide vital diagnostics of plasma dynamics and thermal structure in the solar chromosphere. Multilayer spectral inversion (MLSI) offers a physically interpretable framework for modeling these lines using a finite number of radiative-transfer layers, but conventional MLSI relies on pixel-by-pixel nonlinear least-squares fitting, making it computationally expensive for large imaging spectroscopic data sets. Here, we i…

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astro-ph.GAastro-ph.HE

A Possible Hidden Hot Halo Component Revealed by Joint X-ray and Sunyaev--Zel'dovich Observations

Jiang-Tao Li, Rui Huang, Joel N. Bregman, Q. Daniel Wang, Cameron Pratt

Massive galaxies are expected to host extended halos of hot gas that contain a substantial fraction of their baryons and feedback energy. X-ray observations probe the dense, X-ray-bright component of this circumgalactic medium (CGM), while the thermal Sunyaev-Zel'dovich (SZ) effect is also sensitive to lower-density gas through its integrated thermal pressure. We present the first spatially resolved joint X-ray and SZ analysis of a massive isolated disk galaxy, using deep XMM-Newton observations…

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astro-ph.GA

Does galaxy-scale compactness regulate nebular electron density? A cross-scale test with DESI

Shihong Liu, Yu Rong

Nebular electron density, $n_e$, traces ionized gas in small-scale H\,{\sc ii} regions and diffuse ionized structures, whereas galaxy stellar surface density, $Σ_\star$, measures compactness on kpc scales. Whether these quantities are correlated is therefore a cross-scale question rather than a geometrical identity. We test whether nebular electron density varies systematically with galaxy-scale stellar compactness after controlling for the correlated effects of stellar mass and star-formation r…

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astro-ph.SR

Three-dimensional simulations of accretion disks in pre-CE systems -- II. Accretion efficiency and angular momentum transport

Ana L. Juarez-Garcia, Mike Y. M. Lau, Orsola De Marco, Lionel Siess, Daniel J. Price, Rebecca Nealon

Rapid mass transfer preceding a common envelope event is a critical yet poorly understood stage of binary stellar evolution, setting the initial conditions for the common envelope inspiral and for the formation of compact binary stars. We present three-dimensional smoothed particle hydrodynamics simulations of accretion disk formation during this phase using the Phantom code. We model the final $21~yr$ of Roche lobe overflow from a $7~M_{\odot}$ red giant onto a $1.4~M_{\odot}$ neutron star comp…

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physics.opticsastro-ph.IMphysics.ins-det

Environmental qualification and performance of a CubeSat-scale dual optical frequency comb payload for space applications

Stephanie D. Leifer, Matthew J. Kelley, Natalie Walsh, Ziba Shahriary, Paul Steinvurzel, Chrissy Fortuna, Geoffrey Maul, Adam Darley et al.

We report the environmental qualification and performance of CombSat, a dual optical frequency comb payload designed for deployment on a 12U CubeSat in low Earth orbit. The payload integrates two self-referenced, 200 MHz hybrid fiber-waveguide frequency combs, a narrow-linewidth optical reference, a heterodyne beat detection unit, and FPGA-based control electronics in a total mass of 8.3 kg and volume of 5.7 L, and nominal power consumption of 21W. We describe the mechanical, thermal, and radiat…

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physics.plasm-phphysics.space-ph

Landau Damping Beyond Smooth Velocity Distributions: A Dispersion-Free Lagrangian Time-Domain Framework

Huasheng Xie, Jinsong Zhao

The classic theory of Landau damping requires the velocity distribution function (VDF) to be analytically continued into the complex plane, implicitly requiring analyticity, which imposes constraints far more severe than infinite smoothness. Yet physical plasmas---encountered in discrete simulations, noisy spacecraft measurements, or truncated fusion distributions---are inherently non-analytic. This discrepancy poses a foundational ``smoothness paradox'': why does Landau damping robustly persist…

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