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Research Trends

Latest preprints in space engineering and astrophysics.

nucl-thastro-ph.SRnucl-ex

Nuclear mass table in deformed relativistic Hartree-Bogoliubov theory in continuum, III: nuclei with $8 \leq Z \leq 120$

DRHBc Mass Table Collaboration, Peng Guo, Xiaojie Cao, Kangmin Chen, Qibo Chen, Myung-Ki Cheoun, Yongbeom Choi, Wenmin Deng et al.

The mass table in the deformed relativistic Hartree-Bogoliubov theory in continuum (DRHBc) with the PC-PK1 density functional has been established for nuclei with $8 \leq Z \leq 120$, extended from the previous works for even-even nuclei [Zhang et al. (DRHBc mass table collaboration), At. Data Nucl. Data Tables 144, 101488 (2022)] and for even-$Z$ nuclei [Guo et al. (DRHBc mass table collaboration), At. Data Nucl. Data Tables 158, 101661 (2024)]. The calculated binding energies, two- and one-nuc…

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astro-ph.HEgr-qcphysics.plasm-ph

Jets with Streaks: the Global Dynamics and Structure of Striped Poynting flux dominated Jets

Ho-Sang Chan, Anna Chashkina, Omer Bromberg, Gregory R. Werner, Hayk Hakobyan

Striped jets, characterized by magnetically dominated regions with alternating polarity, can enable fast magnetic energy dissipation in global current sheets formed in between the stripes, and are thus considered as a viable source for the high-energy emission observed in blazars and gamma-ray burst prompt emission. We perform the first global axisymmetric GRMHD simulations that follow the evolution of striped jets from their launching, by accretion of poloidal magnetic loops with alternating po…

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astro-ph.GA

Diffuse Galactic Backgrounds with SPHEREx: A Pilot Study of Background Modeling and Its Impact on Extinction

Wanggi Lim, Jae Hwan Kang, Keunho J. Kim, Young-Jun Kim

We present a spectral analysis of diffuse Galactic background emission using SPHEREx data in a pilot Galactic-plane field, where uncertainty in the estimation of the diffuse infrared background is a major source of systematic uncertainty in extinction studies at near- and mid-infrared wavelengths. We construct channel-resolved background maps across the 0.75--5~$μ$m range using a Large Median Filter approach and then carry the extinction analysis forward only for the cleaner long-wavelength subs…

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astro-ph.IM

The LOFAR Decametre Sky Survey (LoDeSS) I. Survey description and first data release

C. M. Cordun, C. Groeneveld, H. W. Edler, H. K. Vedantham, F. de Gasperin, R. J. van Weeren, J. R. Callingham, E. Osinga et al.

The decametre radio sky ($\sim 10$-$30$ MHz) remains largely unexplored due to strong ionospheric distortions and severe radio-frequency interference. Despite its scientific potential, including access to steep-spectrum synchrotron emission from aged electron populations and coherent radio emission from planetary and stellar magnetospheres, sub-arcminute imaging at these frequencies has only recently become feasible with instruments such as the Low Frequency Array (LOFAR). In this work, we prese…

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

Measured energy exchange in coronal hole solar wind from its solar origins to the heliosphere

Yeimy J. Rivera, Alin R. Paraschiv, Samuel T. Badman, Alberto M. Vasquez, Federico A. Nuevo, Ryan J. French, Momchil Molnar, Roberto Susino et al.

Coordinated ground- and space-based remote observations are used to provide a comprehensive, multi-perspective view of the solar atmosphere that we connect with in situ measurements in the heliosphere centered around the April 8 2024 Total Solar Eclipse observed across North America. These near-contemporaneous, multi-wavelength datasets are used to directly derive the plasma parameters and compute an energy budget of a solar wind stream at its low-coronal birthplace (at an altitude of 1.05Rsun).…

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astro-ph.IMastro-ph.EPphysics.plasm-ph

Xenia: A Table-Driven Code for Astrophysical Multi-Fluid Hydrodynamics

Lei Xing

Models of escaping planetary atmospheres require neutral and ion species with distinct velocities and thermal pressures, coupled by photoionization, recombination, radiation, and collisions. Implementing and extending such coupled models is often hindered when species definitions and stiff interactions are embedded in solver-specific kernels. We present Xenia, a table-driven code for astrophysical multi-fluid hydrodynamics designed to lower this barrier. Species, coupling channels, chemistry, he…

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astro-ph.SR

Global solar compressible convection simulations on non-Cartesian mappings

Grégoire Doebele, Allan Sacha Brun, Maxime Delorme

Context. Modeling the global dynamics of the Sun requires numerical frameworks capable of simulating the highly turbulent convective envelope and its coupling with the stable radiative interior. Simulating such spherical domains in standard cartesian finite-volume codes presents significant topological challenges. Aims. The goal is to extend the cartesian Adaptive Mesh Refinement (AMR) framework Dyablo to non-cartesian geometries in order to perform global solar convection simulations that exten…

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astro-ph.IMgr-qchep-exphysics.optics

Vector field dark matter search with Sagnac interferometer

Yuki Inoue, Quynh Lan Nguyen, Ippei Obata

We present the first calculation showing that a material-asymmetric Sagnac speed meter can improve quantum-noise-limited sensitivity to $B-L$ vector dark matter by nearly two orders of magnitude over a Fabry--Perot Michelson position meter at the low-mass end of the band. We introduce material contrast into a dual-ring interferometer to probe composition-dependent $B-L$ forces and compare the two configurations at equal incident power, input-mirror transmissivity, and cavity round-trip length. F…

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astro-ph.IMgr-qchep-exphysics.optics

Vector field dark matter search with Sagnac interferometer

Yuki Inoue, Quynh Lan Nguyen, Ippei Obata

We present the first calculation showing that a material-asymmetric Sagnac speed meter can improve quantum-noise-limited sensitivity to $B-L$ vector dark matter by nearly two orders of magnitude over a Fabry--Perot Michelson position meter at the low-mass end of the band. We introduce material contrast into a dual-ring interferometer to probe composition-dependent $B-L$ forces and compare the two configurations at equal incident power, input-mirror transmissivity, and cavity round-trip length. F…

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astro-ph.SR

SWAN-SF-V2: A Multivariate Time Series Dataset for Space Weather Data Analytics; Now with AIA and Weighted SHARP Parameters

Dustin Kempton, Griffin Goodwin, Reet Gupta, Viacheslav M Sadykov, Rafal A. Angryk, Berkay Aydin, Manolis K. Georgoulis

Since its original publication in 2020, the SWAN-SF dataset has been cited in over 300 research publications. Here we describe a comprehensive update to the original multivariate time series (MVTS) dataset extracted from solar photospheric vector magnetograms in the Spaceweather HMI Active Region Patch (SHARP) series. As was performed in the original release, our dataset includes a cross-checked NOAA solar flare catalog that facilitates the comparative evaluation of methods designed for solar fl…

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astro-ph.HE

Revisiting damping of Alfvén waves in partially ionized plasmas

Yutaka Ohira

We investigate the damping rate of Alfvén waves by means of the linear analysis of the two-fluid ten-moments system. To treat effects of viscosity in a wide frequency range, we take account of the time evolution of the traceless part of the pressure tensor. In addition, to treat effects of viscosity in a wide range of the ionization degree, we consider interactions between hydrogen atoms and between protons and hydrogen atoms in the equation of the traceless part of the pressure tensor. We find…

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astro-ph.SRastro-ph.GA

The variable mass-loss in low-mass red giant stars: Chromospheric motion across stellar evolution in 47 Tuc

Ian Baeza, L. Monaco, H. Frelijj, Y. Momany, L. Sbordone, S. Zaggia, I. Yegorova, I. Saviane et al.

Mass-Loss (ML) is a critical process that remains poorly understood despite its broad implications across astrophysics. Our current knowledge is insufficient to reproduce ML consistently across stars, particularly in cool, low-mass giants, where the time-variable nature of chromospheres (CHR) ---the region where most physical phenomena powering ML in this regime are expected to occur--- is poorly constrained. We characterize the relevant timescales of CHR variability in red giants and explore co…

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astro-ph.SRastro-ph.IMcs.AIcs.CV

Cross-Modal Solar Image Synthesis: Adapting the Surya Foundation Model from He I 10830 Å to EUV Translation and Coronal Hole Segmentation

Marco Marena, Andrés Muñoz Jaramillo, Qin Li, Haodi Jiang, Jinghao Cao, Wen He, Ziyang Zhang, Chenxi Yuan et al.

The long observational record of He I 10830 Å offers a means to investigate solar morphology before modern extreme-ultraviolet (EUV) imaging. We adapt the Surya solar foundation model to predict Solar Dynamics Observatory/Atmospheric Imaging Assembly (SDO/AIA) 94, 193, and 304 Å images and a coronal hole (CH) probability map from full-disk helium observations. A convolutional input adapter, low-rank backbone updates, and dedicated output decoders learn from temporally paired, geometrically regis…

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gr-qcastro-ph.HEhep-th

The pseudospectrum for gravitational perturbations in Kerr spacetimes

Hongsheng Zhang, Zong-Kuan Guo, Rong-Gen Cai

We study the pseudospectrum of the Kerr black hole for gravitational perturbations with spin weight $s=2$, the case of greatest interest in gravitational-wave astronomy. In the hyperboloidal framework with two-dimensional Chebyshev collocation, we formulate the quasinormal mode problem as a non-self-adjoint eigenvalue problem. For $s\neq0$ the fields $Ψ^{(s)}$ and $Ψ^{(-s)}$ are independent, so the conserved current method yields no single-field energy norm. We overcome this with the Teukolsky--…

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astro-ph.IM

An RFSoC-Based 100 GbE Spectrometer/Correlator for the Baryon Mapping Experiment: Digital Backend Design and On-Sky Validation

Liju Philip, Paul O'Connor, Benjamin Saliwanchik, Anže Slosar, Emi Tamura

We describe the implementation and on-sky commissioning of a two-input spectrometer/correlator built on a Xilinx ZCU208 Radio Frequency System-on-Chip (RFSoC) and deployed on the Baryon Mapping eXperiment (BMX) interferometric array at Brookhaven National Laboratory. The system combines direct RF sampling, FPGA-based correlation, and 100 Gigabit Ethernet (GbE) visibility transport. Two inputs are digitized directly at 1050 MHz without analog downconversion and channelized into 2048 frequency cha…

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

Deriving the Continuous $β$-FPUT Model for Decayless Solar Coronal Oscillations Directly from Resistive MHD

D. Tsiklauri

We present an analytical framework deriving the fluid-continuum $β$-Fermi-Pasta-Ulam-Tsingou ($β$-FPUT) system directly from a third-order resistive magnetohydrodynamics (MHD) expansion to explain persistent, decayless transverse oscillations observed in solar coronal loops. For a continuous wave field propagating along a longitudinal magnetic field with cross-field density variations, a multi-scale expansion demonstrates that quadratic $\mathcal{O}(2)$ advective and Maxwell tension terms vanish…

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astro-ph.EPastro-ph.SR

Stellar magnetic activity and rocky planets in cool dwarf stars

A. K. Stefanov

Exoplanetary astronomy has entered its Golden Age, with humanity having found over 6000 exoplanets to date. The majority of these discoveries have been achieved through transit-photometry and radial-velocity (RV) techniques. While transit surveys lead in discovery numbers, the RV method persists as a vital and indispensable technique in exoplanetary science, particularly in the most prevalent stellar population -- M dwarfs. Their low masses make them the theoretical favourites for RV detections,…

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astro-ph.HEcond-mat.othercond-mat.supr-con

A Vortex Avalanche Model for Pulsar Glitches

M. Ali Alpar, Erbil Gügercinoğlu

Pulsar glitches are thought to involve sudden unpinning and fast transport of large numbers of pinned vortices, possibly triggered by breaking of the neutron star crust solid. Such a vortex avalanche can take place on a fast timescale only if there are pathways for fast vortex motion. Formation of local vortex ``traps'' (regions containing larger than average density of pinned vortices) will provide vortex-free regions surrounding the traps, which can connect to form pathways for fast vortex mot…

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astro-ph.IM

The Robots are Coming: Artificial Intelligence Searching for Extraterrestrial Intelligence

Steve Croft

Breakthrough Listen, humanity's most ambitious search for technosignatures, or evidence of extraterrestrial technology, is carrying out surveys across the sky and across the electromagnetic spectrum, in images, spectra, time series, catalogs, and alerts. Classical techniques still play a major role in the search, but the recent rapid growth in the capabilities of artificial intelligence is enabling new and more powerful algorithms and approaches to be deployed across enormous datasets. Surveys d…

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astro-ph.GA

Feedback-Driven Interaction of Expanding Molecular Clouds in the LDN 1204-Sh2 145-Sh2 140 Complex

C Rishi, Neelam Panwar, L. K. Dewangan, Ajay Kumar Singh

We present a multi-wavelength study of an extended molecular cloud hosting the LDN 1204, Sh2 145, and Sh2 140 regions to investigate the interplay between stellar feedback, cloud dynamics, and star formation. Infrared images reveal two semi-arc/shell-like structures (extent 14-18 pc) associated with known massive O-type stars. Herschel temperature and column density maps identify one hub-filament system (HFS) candidate toward both LDN 1204A and LDN 1204B sub-regions, with peak column densities o…

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astro-ph.GA

Finding the evolutionary link between ULIRGs and radio galaxies

Ayisha Fida, Sumana Nandi, Mousumi Das, K. Rubinur, S. Shanbhog, Preeti Kharb, Barenya Dev

Ultraluminous infrared galaxies (ULIRGs) are the remnants of the major mergers of gas-rich galaxies. They are dusty systems and are extremely luminous in the infrared. Both starbursts and active galactic nucleus (AGN) activity supply power in these systems, but it is not clear how these two activities are related to the overall evolution of the merger remnant. Studies suggest that there may be an evolutionary link between ULIRGs and radio galaxies. Radio observations of ULIRGs are a useful tool…

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astro-ph.GA

Power-law Coupling and Mock Validation of a Surface-density Anisotropy Diagnostic for 85 Rich Galaxy Clusters

Sardor Sharipbayevich Kutlimuratov, Ikram Uralbayevich Tadjibayev

We assess a surface-density anisotropy diagnostic, $A_{\rm ani}$, and its association with the slope $α$ of a power-law galaxy profile. We reprocess 20-annulus profiles of 85 optically rich clusters on a canonical grid, $0 \leq A_{\rm ani} \leq 1.92$, and an extended grid reaching 1.99. Twenty-four canonical fits and 12 extended fits reach their respective upper boundaries; 69 of 85 upper $Δχ^2=1$ bounds remain open, and only four clusters have two-sided intervals. Among 40 preselected power-law…

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astro-ph.HEastro-ph.SR

Fast X-ray Transient EP260321a: Shock Breakout through an Extended Circumstellar Matter

Maokai Hu, Yi Yang, Lifan Wang, Xiaofeng Wang

The Einstein Probe (EP) has discovered a fast X-ray transient, EP260321a, whose optical counterpart was subsequently classified as a broad-lined Type Ic supernova. Its observed rise time of about 690 seconds is inconsistent with theoretical predictions for shock breakout (SBO) from a Wolf-Rayet star, which is typically regarded as the progenitor of envelope-stripped supernovae. In this paper, we propose that EP260321a arose from a SBO within extended circumstellar matter (CSM), where breakout ph…

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astro-ph.EPastro-ph.SRmath-phphysics.space-ph

How dust particles orbiting white dwarfs can reveal undetected co-orbiting exoplanets II. Exoplanets on elliptic orbits

Kyriaki I. Antoniadou, Dimitri Veras

Abridged. We aim to extend Paper I to the eccentric secondary orbit case and now analyse the elliptic restricted three-body problem (ERTBP). Our secondary masses include Ceres, Mercury, Earth, and Neptune so that we can help infer the presence of both large asteroids and planets through our analysis. We study dust particles on both planar (2D-ERTBP) and non-coplanar (3D-ERTBP) orbits. We computed families of 1/1 resonant symmetric and asymmetric periodic orbits in the 2D-ERTBP and 3D-ERTBP. Doin…

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astro-ph.HE

The fading superorbital clock of Hercules X-1 in its 2025--2026 extended low state

Zhenxuan Liao, Xinrui Tie, Yufeng Chi, Guanjun Lin

We present two decades of X-ray monitoring of the eclipsing accreting pulsar Hercules X-1 with \textit{Fermi}/GBM, \textit{Swift}/BAT and \textit{MAXI}/GSC, centred on the extended low state (ELS) that began in 2025 May (the first such event in 22 years) and is still ongoing at the time of writing, $\sim$480~d after its onset. The 35-d superorbital clock does not simply stop in the ELS; it fades. The surviving modulation stays phase-locked to the pre-ELS clock until the flux of the main high sta…

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astro-ph.SRastro-ph.GAastro-ph.IM

Stellar parameters and abundances for 3.2 million DESI DR1 spectra using machine learning

Nagaraj Vernekar, Michael Hayden, Sara Lucatello

We present a machine-learning pipeline for determining stellar parameters and chemical abundances from spectra observed by the Dark Energy Spectroscopic Instrument (DESI). Building on the model-driven Payne framework, we train an artificial neural network on ~370,000 synthetic spectra spanning FGK stars, and fit the network directly to the flux-calibrated, un-normalised spectral energy distribution (SED) of each star, rather than to a continuum-normalised spectrum as done by DESI's official Stel…

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astro-ph.HEhep-ph

Dark matter in neutron stars: two-fluid $f$-mode oscillations in full general relativity

Prashant Thakur, Ishfaq Ahmad Rather, Y. Lim

A dark-matter core and a soft nuclear equation of state can produce similar mass--radius signatures, motivating a complementary probe through the $f$-mode spectrum. We compute quadrupolar $f$-mode frequencies and gravitational-wave damping times in full general relativity for cold, nonrotating neutron stars admixed with self-interacting bosonic dark matter (DM). Our two-fluid survey spans 21 nuclear equations of state covering nucleonic, hyperonic, $Δ$-admixed, and combined hyperon--$Δ$ composit…

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astro-ph.IMcs.LG

Shared Geometry Is Not Shared Physics: A Layerwise Test of the Platonic Representation Hypothesis in Astronomy

Kshitij Duraphe, Aravind Kannappan, Dun Li Chan, Okiki Famutimi, Yaswant Sai Ejjagiri, Michael J. Smith, John F. Wu

In this paper we investigate whether geometrically aligned astronomical representations are also scientifically interchangeable. We analyze every layer's representation from 36 pretrained models using cross-matched optical images, infrared images, and spectra. All 139 analyzed model-survey comparisons show significant local-neighborhood alignment somewhere in the network after accounting for the search over depth. However, alignment does not generally increase with network depth and can be stron…

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astro-ph.IM

LoFreq-SETI: A Low-Frequency Technosignature Search Pipeline for the LWA Swarm

Craig A. Taylor, Lillian Ekness, Chenoa Tremblay

The search for extraterrestrial intelligence (SETI) is conducted across the electromagnetic spectrum to understand the prevalence and distribution of intelligent life in the universe. At radio frequencies, this effort focuses on searching for "technosignatures", observable indicators of technological activity consistent with our understanding of an advanced civilization. Historically, the microwave regime from 1-10 GHz has been the primary frequency range searched for these technosignatures, but…

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astro-ph.SRastro-ph.IM

A forest of emission lines observed by Sunrise III/SUSI above the solar limb

J. S. Castellanos Durán, F. A. Iglesias, S. K. Solanki, A. Lagg, I. Milic, H. N. Smitha, D. Vukadinović, T. L. Riethmüller et al.

We present off-limb spectroscopy using low-straylight data from the Sunrise Spectropolarimeter and Imager (SUSI) onboard the Sunrise III stratospheric solar observatory. A spatial scan with SUSI's slit almost parallel to the local limb reached from within the solar disc to 6.5 Mm off-limb. The wavelength range spanned from 407.6 to 410.25 nm. We detected a total of 174 spectral lines in emission off-limb, a 2.5-fold increase over previous reports. Surprisingly, 122 of these lines begin to appear…

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