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Research Trends

Latest preprints in space engineering and astrophysics.

astro-ph.SR

An Halpha survey of infrared bow-shocks around OB-type stars

Kuljeet Singh Saddal, Michaela Kraus, Dieter H. Nickeler, Tiina Liimets, Sergey Karpov, Olga V. Maryeva

Bow shocks (BSs) around massive stars are commonly identified in mid-infrared (MIR) surveys. In contrast, systematic optical investigations of these structures remain scarce with only a few possible detections reported so far. We performed a targeted Halpha imaging survey of 78 IR BS candidates compiled from literature catalogues. Observations were obtained with multiple ground-based facilities and complemented with archival MIR images from Spitzer and WISE. For the detected bow structures, geom…

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astro-ph.HE

R-process nucleosynthesis from magnetar giant flares in neutron star--white dwarf mergers: A unified picture for peculiar long gamma-ray bursts

Shu-Qing Zhong, Long Li, Le Zou, Ji-Gui Cheng, Yan-Zhi Meng, Jia-Hong Gu

Peculiar long gamma-ray bursts (GRBs), exemplified by GRBs 211211A and 230307A, exhibit a long-duration multi-component prompt emission, an X-ray plateau in their afterglow, and a kilonova signature. Their origin remains highly debated. In this work, we present a unified picture for these events based on neutron star--white dwarf (NS--WD) mergers involving a pre-merger magnetar and a massive WD. In this picture, tidal disruption of the WD forms a constant-entropy accretion disk. Hyperaccretion f…

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astro-ph.IM

Modelling Radio Frequency Interference on the Lunar Farside

Charlie K. Ashe, Ella J. Marshall, Evan F. Keane, Steve Prabu, Richard Lynch, David R. DeBoer

Technological progress is a double-edged sword in the world of radio astronomy: improvements in antennas, receivers, and digital backends increase sensitivity, but rapid growth in terrestrial and orbital communications has caused a steep rise in radio-frequency interference (RFI). Modern datasets have become increasingly contaminated by RFI that is difficult to remove and can mimic or obscure astrophysical signals, complicating the search for objects such fast radio bursts (FRBs), pulsars, and t…

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astro-ph.SRcs.CV

A Modern ConvNet for Solar Filament Detection

J. R. Hu, Q. Hao, Z. Zheng, P. F. Chen, C. Li, Y. Meng

Automated solar filament detection using deep learning faces several challenges. Semantic segmentation of solar filaments is a complicated multiscale feature extraction task with long-tail distribution. Furthermore, a large-scale, highly complete, and finely detailed dataset has become mandatory for providing abundant information. To address these challenges, we present a series of machine learning approaches to develop a solar filament detection workflow that performs superbly. First, we manual…

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astro-ph.GAastro-ph.HE

Time-Domain Dust Astrophysics. I. Polarization Flares, Polarization-Angle Reverberation, and Fossil Imprints in Supernova-Illuminated Clouds

Thiem Hoang

Cosmic transients can dramatically enhance the local radiation field on timescales of days to months. Using the time-domain TransRAT framework, which self-consistently evolves grain heating, alignment, rotational disruption, and switching of the alignment axis between the magnetic field (B-RAT) and the radiation direction (k-RAT), we predict the time-dependent dust polarization of a dense cloud illuminated by a Type~IIP supernova at different distances. We identify four key signatures. First, fo…

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astro-ph.SR

Identification of unresolved binaries in the VVV b294 tile: A Pro-Am collaboration using the Virtual Observatory

M. Cortés-Contreras, P. Cruz, E. Solano, J. L. Navarro, T. Poyato Romero, R. Benavides Palencia, C. Cagigal-Olay, M. Zamora Rodríguez et al.

Stellar binaries and multiples are common objects. Their identification and characterization are primarily limited by the angular resolution of current instrumentation, survey depth and dynamic range. Towards the Galactic plane, stellar crowding further complicates these studies. We aim to identify unresolved binaries with good astrometric solutions and M dwarf primaries in the b294 field from the Vista Variables in the Vía Láctea (VVV) survey using publicly available data. We examine the catalo…

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astro-ph.IMphysics.ins-det

The beamformed trigger of RNO-G: its design and in-field performance

RNO-G Collaboration, :, S. Agarwal, J. A. Aguilar, N. Alden, S. Ali, P. Allison, M. Betts et al.

The Radio Neutrino Observatory in Greenland (RNO-G) is a neutrino detector under construction at Summit Station, with 8 out of a planned 35 stations currently deployed. We have designed and deployed a new phased array (PA) trigger based on delay-and-sum beamforming and power integration. This trigger improves detector performance by suppressing thermal noise and better targeting neutrino-induced Askaryan signals. The new PA trigger has been deployed since the 2025 season. The trigger performance…

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astro-ph.GAastro-ph.HE

Cosmic ray heating of cold streams: Implications for the gas supply and growth of massive galaxies

Ellis R. Owen, Nicolas Ledos, Evangelia Ntormousi, Shinsuke Takasao, Kentaro Nagamine, Sebastiano Cantalupo

Recent observations have demonstrated the presence of cosmic rays (CRs) in cosmic-web filaments. Cold streams supply gas inflows from these filaments into massive galaxies during the cosmic noon. As these streams are expected to be magnetised, external cosmic-web CRs may become entrained with this inflowing gas. We aim to determine whether this externally-supplied CR population can deposit energy to alter or disrupt the supply of cold gas to galaxies. We couple a spectrally-resolved CR transport…

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astro-ph.SR

A survey for variable young stars with small telescopes - XI. Spot Lifetimes and Coverage Distributions

Dirk Froebrich, Carys Herbert, Aleks Scholz, Benjamin W. Ryan, Siegfried Vanaverbeke, Jochen Eislöffel, Cledison Marcos da Silva, Michel Michaud et al.

We present a homogeneous analysis of rotational variability and spot properties in young stellar objects across multiple star-forming regions observed by the Hunting Outbursting Young Stars (HOYS) project. From over 2000 candidate members, we identify 144 YSOs with robust periodic signals and well-constrained multi-band amplitudes. The sample has a median age of $\sim$1~Myr, effective temperatures of 3500--6500~K (masses $\sim$0.6--2~M$_\odot$), and is dominated by Class~2 objects, one third of…

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astro-ph.HE

Evolution of Calvera and Descendants of Calvera-like Central Compact Objects

Ali Arda Gencali, Unal Ertan, Fatmanur Ertugrul, Seyda Demirok, Ndiogou Niang

Calvera (1RXS J141256.0+792204) is an isolated neutron star recently classified as a central compact object (CCO) after its association with the supernova remnant (SNR) candidate G118.4+37.0. In this work, we investigate the long-term evolution and descendants of Calvera and the CCOs with similar initial conditions in the fallback disc model. We show that the observed spin period, period derivative, and X-ray luminosity of Calvera can be reproduced simultaneously with a magnetic field strength o…

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astro-ph.HEgr-qc

Transport Properties of the MRI in Differentially Rotating Neutron Stars

Harshraj Bandyopadhyay, Peter Hammond, David Radice

We perform three-dimensional, high-resolution, general-relativistic magnetohydrodynamics (GRMHD) simulations of the magnetorotational instability (MRI) in differentially rotating neutron stars. We consider both high-mass models which collapse either promptly, or due to the outward transport of angular momentum removing rotational support, and lower-mass models, which remain stable even after solid-body rotation has been achieved. We measure effective transport coefficients of the resulting turbu…

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astro-ph.SR

On the Modeling of Kink Oscillations in Fine-Structured Coronal Loops with Field-aligned Nonlinear Longitudinal Disturbances

Shakti Singh, Balveer Singh, V. S. Pandey, Shilpa Patra, Preeti Verma, Peter H. Yoon

We investigate the influence of nonlinear longitudinal disturbances, triggered by an initial field-aligned velocity flow, on the damping of standing kink oscillations in fine-structured, cool coronal loop strands under isobaric conditions. Using two-dimensional ideal MHD simulations, we model different realistic flow geometries, bounded, unbounded, and external, and quantify their impact on wave excitation, damping, and energy leakage. Our modelled loop strand incorporates strong density contras…

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hep-exastro-ph.IMhep-ph

Dark Matter Searches with Sodium Iodide Detectors

Maria Martinez, Reina H. Maruyama, Maria Luisa Sarsa

The search for the identity of dark matter remains one of the most intriguing challenges in physics today, driving innovative advances in experiment and theory. Thallium-doped sodium iodide (NaI) detectors have played a pivotal role in this context. This review outlines the scientific landscape surrounding NaI detectors, emphasizing their role in the broader context of dark matter research. We begin with a brief description of characteristics that make these detectors well-suited for dark matter…

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astro-ph.GA

Kinetic and H-atom product study of the C + C6H6 reaction at low temperatures

Kevin M. Hickson, Jean-Christophe Loison

The reactions of atomic carbon in its ground electronic state configuration, C(3P), are potentially important processes in astrochemistry due to the large abundance of C(3P) atoms in the interstellar medium (ISM) and its high overall reactivity towards a wide range of molecules. Although benzene, C6H6, has not been detected in the dense ISM, its presence at high abundance levels is inferred through the detection of functionalized derivatives. Here we present a combined experimental and astrochem…

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hep-phastro-ph.SRhep-ex

A High-Precision Numerical Framework for Time-Varying Solar Neutrino Flux with Full Earth Matter Oscillation Corrections for Global Underground Laboratories

Keyu Han, Isabella Yin, Kaoru Yagi, Kevin Yifan Jiang, Xiangpan Ji, Shaomin Chen

Solar neutrinos have been studied for over half a century to test both the Standard Solar Model and the electroweak sector of the Standard Model of particle physics. Contemporary experiments are now entering an era of high-precision measurements, demanding corresponding theoretical predictions with sub-percent accuracy to enable meaningful comparison. In this paper, we identify and analyze the essential physical and computational components required to compute solar neutrino fluxes with high fid…

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astro-ph.GAastro-ph.EPastro-ph.IMastro-ph.SR

A Split-Flux Method for Dust-Gas Two-Fluid Simulations from Strong to Weak Coupling

Kazunari Iwasaki

We develop a new method for simulating pressureless fluids of neutral dust coupled to magnetohydrodynamic gas through dust-gas drag. It has been pointed out that, in the strong-coupling regime, dust-gas multifluid methods suffer from artificial variations in the dust-to-gas mass ratio when the dust and gas are evolved with independent numerical fluxes. This problem arises from inconsistencies between the dust and gas mass fluxes. In the strong-coupling limit, the dust-to-gas mass ratio is advect…

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astro-ph.COastro-ph.GA

Constraining the $z \approx 1$ neutral hydrogen (HI) distribution

Minal Chhabra, Raghunath Ghara, Somnath Bharadwaj

We constrain the $z \approx 1$ HI distribution by jointly modeling two independent, existing observations of the 21-cm signal, the HI density parameter $Ω_{\rm HI}$ measured using uGMRT by stacking the 21-cm emission from blue, star-forming galaxies, and the 21-cm autocorrelation power spectrum (PS) measured using CHIME. We assign HI to the dark matter halos in a cosmological simulation using an HI mass-halo mass (HIHM) relation with three free parameters whose values we estimate by performing a…

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astro-ph.HEastro-ph.CO

Constraints on the magnetic field in the hadronic scenario for the origin of the radio halo in the A1795 galaxy cluster

P. Marchegiani, V. Vacca, F. Loi, F. Govoni, M. Murgia

The radio halo in the cool-core galaxy cluster A1795 has recently been proposed to be of hadronic origin, because it extends on a scale of the order of Mpc, where no turbulence is expected to be injected in a relaxed cluster. In this paper we aim to constrain the properties of the non-thermal protons and the cluster magnetic field strength under the hypothesis of a hadronic origin of the radio halo at the light of the available gamma ray upper limit in this cluster. We assume a radial profile an…

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astro-ph.SR

A Detailed Spectroscopic Study of the WN6ha + O5 Colliding-wind Binary WR 25

Eric Gosset, Roberto Gamen, Laurent Mahy, Nidia Morrell, Hugues Sana, Rodolfo Barbá

Massive stars have a major impact on their environment in their host galaxy. Observational determinations of their physical parameters are required to better constrain evolutionary models. In this context, the binary system WR 25 whose dominant spectral type is that of a nitrogen sequence Wolf-Rayet star, is of particular interest. It exhibits the highest known hydrogen content among the Milky Way Wolf-Rayet stars, as well as additional absorption lines. It is most probably an object still on th…

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astro-ph.IMphysics.optics

Sensitivity of Laguerre-Gaussian Modes to Misalignment and Mode Mismatch in Gravitational-Wave Detectors

Liu Tao, Matteo Barsuglia

Higher-order Laguerre-Gaussian (LG) modes have broader and more uniform transverse intensity distributions than the fundamental Gaussian mode, making them attractive for precision optical applications. In gravitational-wave detectors, their enhanced spatial averaging of thermally driven test-mass fluctuations can reduce thermal noise. Their implementation, however, requires efficient coupling of the injected beam to the target cavity eigenmode. Residual misalignment and mode mismatch couple powe…

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gr-qcastro-ph.HEhep-th

Entropy dynamics in gravitational collapse: From Minkowski breaking to de Sitter thermodynamics

Francisco S. N. Lobo, Manuel E. Rodrigues

The origin of black hole entropy remains one of the deepest mysteries in modern physics. Two recent developments offer complementary perspectives on this puzzle: the entropy release from regular Schwarzschild black holes with a de Sitter core (the OCK construction), and the local thermodynamics of the de Sitter vacuum (Volovik). In the OCK framework, the inner horizon carries positive Bekenstein-Hawking entropy $S_{\rm inner}=πh_c^2$ that is gradually released as the core shrinks, until a classi…

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gr-qcastro-ph.SRphysics.class-ph

The Magnusian generator for dissipative systems and application to leading 2.5PN radiation-reaction dynamics

Francisco M. Blanco

The Magnusian is a phase-space function that generates finite-time evolution through nested Poisson brackets. It is related to several familiar generators of classical dynamics, including the radial action, the eikonal phase and related quantities. In this work, we extend the Magnusian framework to systems with dissipation and nonlocal-in-time interactions using the in-in formalism, also known as the Schwinger-Keldysh or Galley formalism. This framework is particularly natural for binary dynamic…

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astro-ph.GA

Radio Jet Properties of the Flaring Gamma-Ray Blazar PKS 0346-27

Máté Krezinger, Sándor Frey, Krisztina É. Gabányi

The blazar PKS 0346-27 at redshift z=0.991 is among the most distant extragalactic sources detected in very high energy gamma-rays. It underwent a major flare reaching TeV energies in November 2021. Recent modelling of its spectral energy distribution favoured a single-zone proton--synchrotron-dominated hadronic model with bulk Lorentz factor Gamma=10 over a single-zone leptonic jet model with much higher Gamma. Here we analyse archival radio data to give independent estimates of the jet bulk Lo…

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astro-ph.SRastro-ph.HE

Testing the theory of colliding winds: the periastron passage of 9 Sagittarii. II. Radio monitoring

R. Blomme, G. Rauw, D. Volpi, Y. Nazé, R. Prinja

Colliding winds in massive-star binaries generate non-thermal radio emission and an increased X-ray emission. We study the radio emission of the non-thermal emitter 9 Sgr, which is a long-period and highly eccentric binary. We conducted a monitoring campaign of 9 Sgr around its 2013 - 2014 periastron passage, obtaining radio, X-ray and optical spectroscopy data. In this paper, we analyse the radio data. The radio data at 3.6, 6 and 20 cm show a maximum near periastron. Other non-thermal radio em…

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astro-ph.COastro-ph.GA

Local luminosity functions of galaxies at (sub)millimeter wavelengths from Planck surveys

Matteo Bonato, Gianfranco De Zotti

The Planck all-sky surveys at (sub)millimeter wavelengths enable us to accurately determine the corresponding local luminosity functions up to the highest luminosities. The detected galaxies are strictly local, so evolutionary effects, which are known to be particularly strong at these wavelengths, are not a problem. However, previous studies have so far relied only on the Planck Early Release Compact Source Catalog (ERCSC) for this purpose. Another important improvement over earlier estimates i…

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astro-ph.SRastro-ph.EP

Locate a stellar flare from the M dwarf LAMOST J1332+5057

Guang-Wei Li, Gui-Ping Zhou, Bing Du, Yan-Xin Guo, Wei-Hua Wang

Young M-type stars exhibit frequent flares, which would seriously impact their habitable planets. Since stellar surfaces cannot be resolved, flare locations remain unknown. Here, by using the Mg I b emission line in LAMOST spectra, the location of a stellar flare from a young M dwarf is pinpointed at $ (-123.0^{+8.0}_{-5.8}, 80.5^{+2.9}_{-3.2})$ in degree in the polar region. Our method can be used to accurately locate stellar flares. This would enable us to assess the impact of stellar flares o…

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astro-ph.GA

Effects of temperature-dependent optical properties on the determination of interstellar dust masses

Lapo Fanciullo, Jonathan P. Marshall, Francisca Kemper, Peter Scicluna, Sundar Srinivasan

Accurate measurements of interstellar dust mass are key to answering several astrophysical questions. A common method of obtaining the mass is to fit the far-infrared thermal emission of the dust with a modified blackbody model; however, this method is subject to several systematics. In particular, how temperature-dependent dust optical properties affect fit results has received little attention. We provide the first quantification of this effect based on experimental measurements of optical pro…

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physics.plasm-phastro-ph.HEphysics.acc-ph

Quasistatic modeling of ultrarelativistic beam-plasma instabilities

P. San Miguel Claveria, L. Gremillet, X. Davoine, Q. Labro, A. Matheron, M. Tamburini, F. Fiuza, S. Corde et al.

Relativistic particle beams propagating through dense ambient plasmas are susceptible to streaming instabilities that can govern the system dynamics in various astrophysical and laboratory settings. For an unmagnetized, collisionless plasma pervaded by a dilute, cold relativistic beam, the dominant instabilities are the quasielectrostatic, oblique two-stream (OTSI) and the essentially magnetic, current filamentation instability (CFI). While their linear and nonlinear properties have been researc…

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astro-ph.IM

First high-contrast results on THD2 testbed after infrastructure upgrade

Iva Laginja, Pierre Baudoz, Rémi Soummer, Emiel H. Por, Axel Potier, Johan Mazoyer, Raphaël Galicher, David Doelman et al.

We present the first scientific results delivered by the upgraded THD2 high-contrast imaging testbed. We report two advances enabled by its improved stability and broadband performance. First, for the Roman Space Telescope, we demonstrate that Gaussian-shaped diversity probes outperform the baseline sinc probes by reducing non-linearities, supporting higher probe amplitudes, and improving electric field estimation efficiency. These results have led to their prioritization as an enhanced early ob…

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physics.plasm-phastro-ph.HE

Modeling ultrarelativistic streaming plasma instabilities under the quasistatic approximation

P. San Miguel Claveria, Q. Labro, X. Davoine, A. Matheron, M. Tamburini, S. Corde, L. Gremillet, F. Fiuza et al.

Plasma streaming instabilities excited by relativistic charged particle beams play a pivotal role in astrophysical and laboratory environments. Their numerical study, however, is challenged by the disparity in spatiotemporal scales between the background plasma and beam particles, which can differ by several orders of magnitude for tenuous, ultrarelativistic beams. Here, we exploit the quasistatic approximation (QSA) to develop a new theoretical framework capable of capturing the full unstable s…

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