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Research Trends

Latest preprints in space engineering and astrophysics.

astro-ph.HE

Probing the details of relativistic electrons with multifrequency observations of M87 black hole

J. G. J. Keuper, M. Moscibrodzka

Beginning in March 2026, the Event Horizon Telescope (EHT) conducted a two-month observing campaign aimed at obtaining the first time-resolved sequence of images of the black hole M87* at the center of the Virgo A galaxy. The primary scientific objectives of this campaign are to constrain the black hole spin and to investigate the temporal variability of the magnetic field and plasma properties within the horizon-scale jet-launching region. In this work, we present theoretical predictions for th…

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astro-ph.IM

An RFSoC-based Backend and Timing System for the Balloon-borne Very Long Baseline Interferometry Experiment

Mayukh Bagchi, Felix M. Thiel, Laura M. Fissel, Maggie Oxford, Lindy Blackburn, Rafael Costa, Vincent L. Fish, Daryl Haggard et al.

We present the design and performance characterization of the digital backend and precision-timing system for the Balloon-borne Very Long Baseline Interferometry Experiment (BVEX), a pathfinder for high-frequency stratospheric VLBI at 22 GHz. The backend uses one of the four 14-bit analog-to-digital converter inputs on an AMD-Xilinx RFSoC 4x2. Although the converters support sampling rates up to 5 GSPS, the flight configuration digitizes the 2-4 GHz intermediate frequency at 4.096 GSPS. CASPER f…

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astro-ph.IM

The MICADO first light imager for the ELT: the PSF Reconstruction Software

Andrea Grazian, Fernando Pedichini, Matteo Simioni, Jani Achren, Carmelo Arcidiacono, Luca Cortese, Ric Davies, Marco Gullieuszik et al.

The MICADO instrument for the ESO ELT will provide Adaptive Optics (AO) diffraction-limited NIR imaging and spectroscopy. A critical component of MICADO is the Point Spread Function Reconstruction (PSF-R) Software, which is designed to perform a blind reconstruction of the PSF for all observations using AO telemetry data only, both with the Single Conjugate (SCAO) and Multi-Conjugate Adaptive Optics (MCAO) modes of MICADO. The SCAO PSF-R Pipeline is currently being completed, and validation with…

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astro-ph.IM

Towards First Light for MICADO: Validation of the PSF-R service with real data

Matteo Simioni, Luca Cortese, Roland Wagner, Carmelo Arcidiacono, Andrea Grazian, Marco Gullieuszik, Elena Masciadri, Elisa Portaluri et al.

MICADO, one of the ELT first-light instruments, will rely on point-spread-function reconstruction (PSF-R) to meet scientific requirements, especially for SCAO observations of targets that lack bright reference stars nearby. PSF-R will be performed in post-processing using only AO telemetry, recorded simultaneously with the science data. For SCAO observations, both on- and off-axis PSFs will be delivered. We present the current status and results from an ESO TTR campaign begun in 2023, targeting…

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astro-ph.GAastro-ph.SR

Testing Chemical Tagging with LAMOST: Intrinsic Abundance Dispersion of Subgiant Stars in the Galactic Disk

Wu Yaqian, Xiang Mashing, Zhao Gang, Jiang Ruizheng, Li Zhuohan, Bi Shaolin, Zhang Meng

The scatter in elemental abundances among stars of similar age and metallicity reflects chemical inhomogeneity in their birth environments, making abundance scatter a key observable for chemical-tagging studies of Galactic formation and evolution. Using a large sample of subgiant stars with precise ages and elemental abundances derived from LAMOST low-resolution spectra, we investigate the intrinsic chemical abundance scatter of the low-$α$ thin disk near the solar neighborhood ($7 < R < 10$ kpc…

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astro-ph.GAastro-ph.SR

Testing Chemical Tagging with LAMOST: Intrinsic Abundance Dispersion of Subgiant Stars in the Galactic Disk

Wu Yaqian, Xiang Maosheng, Zhao Gang, Jiang Ruizheng, Li Zhuohan, Bi Shaolan, Zhang Meng

The scatter in elemental abundances among stars of similar age and metallicity reflects chemical inhomogeneity in their birth environments, making abundance scatter a key observable for chemical-tagging studies of Galactic formation and evolution. Using a large sample of subgiant stars with precise ages and elemental abundances derived from LAMOST low-resolution spectra, we investigate the intrinsic chemical abundance scatter of the low-$α$ thin disk near the solar neighborhood ($7 < R < 10$ kpc…

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astro-ph.SR

Evidence for CME--CME Interaction in a Magnetic-Cloud-Like Ejecta: Insights from Multipoint Observations and Polytropic Analysis

Jyoti Sheoran, Vaibhav Pant, Eva Weiler, Vivek Menon, Emma E. Davies, Christian Möstl, Dipankar Banerjee, M. Saleem Khan et al.

Using in-situ observations from Solar Orbiter, STEREO-A, and Wind, we investigate the heliospheric evolution of an interplanetary coronal mass ejection (ICME). The magnetic ejecta (ME) shows a magnetic-cloud-like (MCL) configuration: a front region in which the magnetic field rotates and its magnitude declines, followed by a weakly rotating "back region" of nearly constant field magnitude. Near-Sun EUV and white-light observations reveal two fast CMEs launched in rapid succession and interacting…

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astro-ph.SR

Evidence for plasmoid formation related to a hot UV burst in the solar atmosphere

Mats Ola Sand, Luc Rouppe van der Voort, Souvik Bose, Daniel Nobrega-Siverio, Jonas Thoen Faber, Reetika Joshi, Ignasi Josep Soler Poquet

Magnetic reconnection in the solar atmosphere drives energetic phenomena such as Ellerman bombs, UV bursts, and surges. We used coordinated observations from the Swedish 1-m Solar Telescope (SST), IRIS, SDO, and the Hinode/X-ray Telescope (XRT) to analyze an active region with strong magnetic flux emergence. This region displayed long duration UV burst activity, occurrence of multiple Ellerman bombs, and recurrent ejection of surges. Chromospheric imaging show sthe presence of a dome-like struct…

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astro-ph.HEgr-qchep-phhep-th

Cosmological Evolution of Primordial Black Holes: UV/IR Decoupling and the KM3NeT 220 PeV Neutrino Anomaly

Debdatta Dey, Tausif Parvez, S. Shankaranarayanan

The recent observation of a 220 PeV neutrino event (KM3-230213A) by the KM3NeT observatory presents a formidable challenge to standard astrophysical source models. We investigate the hypothesis that this ultra-high-energy signature originates from the terminal evaporation burst of a Primordial Black Hole (PBH). Since PBH evolution spans cosmic history, static vacuum approximations fail to capture early-universe dynamics. Embedding the PBH in a cosmological background via the McVittie spacetime,…

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astro-ph.GA

Generating the wide sequence of Diffuse Galaxies with de Broglie waves of Dark Matter

Jiashuo Zhang, Tom Broadhurst, Alvaro Pozo, Tzihong Chiueh, Justin Schive, Jeremy Lim, Francine Marleau, Tomomi Sunayama et al.

Extensive Euclid satellite imaging at low surface brightness has revealed that most nearby galaxies are diffuse-looking spheroids, where the stellar radius increases monotonically over three decades in luminosity. We argue this Diffuse Galaxy sequence results from internal stellar diffusion by Wave Dark Matter ($ψ$DM), as wave energy is transferred to star orbits over time. In particular, the soliton random motion scatters central stars onto radial orbits that become enhanced with each passage t…

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astro-ph.GA

Resonantly Scattered CIV Emission in Local Star-forming Galaxies: Radiative Transfer Constraints on High-ionization Gas in Reionization Analogs

Zhihui Li, Danielle A. Berg, Simon Gazagnes, Timothy Heckman, Max Gronke, Dawn K. Erb, John Chisholm

Rest-frame ultraviolet emission lines are diagnostics of hard ionizing spectra and highly ionized gas in galaxies resembling the sources of cosmic reionization. Nebular CIV emission traces both intrinsic line production and resonant scattering through its velocity-resolved profile. Previous studies have treated CIV empirically, using integrated fluxes, equivalent widths, and line ratios rather than modeling the radiative transfer (RT) shaping the emergent profiles. We present the first systemati…

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astro-ph.GA

Tracing Warm Gas through C IV Radiative Transfer

Jin Lim, Seok-Jun Chang, Max Gronke, Fabrizio Arrigoni Battaia, Hee-Won Lee, Kwang-Il Seon

The C IV $λ\lambda1548,1551$ resonance doublet is a key tracer of warm gas ($T\sim10^5\,{\rm K}$) within and around galaxies. Recent observations have detected this line in both absorption and emission, revealing asymmetric profiles in galaxies and spatially extended haloes around active galactic nuclei (AGNs). Resonance scattering can strongly modify the emergent spectra and spatial distributions, complicating their interpretation. Using 3D Monte Carlo radiative transfer simulations, we study C…

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astro-ph.HE

Spin-down of the accreting magnetar candidate 4U 0114+65: possible first evidence for a strong coupling regime

Graciela Sanjurjo-Ferrín, Jose Miguel Torrejón, Konstantin Postnov, Jose Joaquín Rodes-Roca, Lida Oskinova, Jessica Planelles-Villalva

4U~0114+65 is a high-mass X-ray binary composed of the B1\,Ia supergiant V*~V662~Cas and one of the slowest known accreting neutron stars, with a spin period of $\sim$9.4 ks. In 2025, its long X-ray pulsations became undetectable in \textit{Swift}/BAT monitoring, motivating a Director's Discretionary Time observation with \textit{XMM-Newton}. We compare this observation with a 2015 \textit{XMM-Newton} observation, when the source was brighter and clearly pulsed, and analyze the long-term spin ev…

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astro-ph.IMastro-ph.EPcs.AImath.OCphysics.space-ph

Continuous Learning of Gravity Field Irregularities Around Small Bodies via Neural Hamiltonian ODEs

Giacomo Acciarini, Dario Izzo

We propose to learn the unknown dynamics in the proximity of a small body directly from tracking data, representing them as a feed-forward neural network embedded in the system Hamiltonian. The equations of motion form a Neural Hamiltonian Ordinary Differential Equation, whose variational equations provide exact training gradients: estimation uses position and velocity arcs at realistic noise levels, without acceleration or potential labels, and a continual learning approach warm-starts the netw…

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astro-ph.GA

The properties of central stellar knots embedded in galactic bulges of CIELO simulations

Belén Acosta-Tripailao, Patricia B. Tissera, Manuela Zoccali, Jenny Gonzalez-Jara, Brian Tapia-Contreras, Ignacio Muñoz-Escobar, Susana Pedrosa, Nelson D. Padilla et al.

Deeply bound stellar substructures of about 1 kpc at the center of bulges are found in a subset of galaxies from the cosmological chemo-hydrodynamical zoom-in CIELO simulation suite. They were identified as stellar overdensities at the lowest binding energies in each galaxy's circularity-energy $(ε, E)$ plane. We refer to these overdensities as stellar knots. We aim to characterize their properties in the context of bulge assembly using CIELO simulated galaxies spanning a wide range of stellar m…

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astro-ph.EPphysics.geo-ph

Lava Tube Exploration with LunarLeaper

Anna Mittelholz, Simon C. Stähler, Valentin T. Bickel, Jordan Aaron, Aurelie Cocheril, Alessandro Ghirotto, Matthias Grott, Svein-Erik Hamran et al.

Lunar pits, some of which are interpreted as collapse features into underlying lava tubes, expose otherwise inaccessible stratigraphy and may provide entry points to subsurface voids that preserve records of lunar volcanism and offer potential sites for future human exploration. We synthesize the current state of knowledge on lunar pits and lava tubes, covering their morphological characteristics, classification, proposed formation mechanisms, mechanical stability, and detection from orbit. We t…

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astro-ph.GAastro-ph.CO

Constraints on the fuzzy dark matter mass using globular clusters in dwarf galaxies from Euclid ERO data

Lisa Besnard, Pierre Boldrini, Paola Di Matteo, Chervin Laporte, Teymoor Saifollahi

We constrain the particle mass of the fuzzy dark matter model using globular cluster candidates in dwarf galaxies, from the Euclid Early Release Observations, within the Fornax and Perseus galaxy clusters. We model the orbital evolution of globular clusters by combining fuzzy dark matter density profiles with the corresponding dynamical friction formalism, and integrate their orbits using galpy. In the fuzzy dark matter framework, both the halo density profile and the dynamical friction force ar…

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astro-ph.GA

No Detectable One-halo Galactic Conformity Signal with Halo-mass Estimates Consistent with Weak-lensing Constraints

Dingyi Zhao, Yingjie Peng, Luis C. Ho, Houjun Mo, Cheqiu Lyu, Kai Wang, Yijun Wang, Tao Wang et al.

One-halo galactic conformity is the tendency for satellites in halos with quenched centrals to have lower star-formation activity than those in halos with star-forming centrals at fixed halo mass. It is an important probe of the galaxy--halo connection and halo-wide quenching processes that may couple central and satellite evolution. However, its existence remains controversial, because conformity must be measured at fixed halo mass, while halo masses are difficult to estimate accurately. In thi…

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astro-ph.HE

Nonbirefringent model of orthogonal polarization modes in radio pulsars - New view on S swing and mode structure in pulsar beam

J. Dyks, A. Frankowski

Two orthogonal polarization modes observed in radio pulsar signals have long been attributed to proper modes of wave oscillation in strongly magnetized plasma. Yet it has been shown recently that they show up readily for extended emission regions that produce incoherently-superposed polarization signal. In this paper we present a two-dimensional polarization model based on incoherent superposition of radio signals. The model involves a single proper mode, say the O mode, but leads to the appeara…

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astro-ph.SR

Non-axisymmetric Transport of Magnetic Flux Tubes: A Mechanism for Joy's Law and Poloidal Field Generation via Meridional Flows

Andrey G. Tlatov

We present a new scenario for the solar $αω$-dynamo based on the interaction of asymmetric magnetic flux tubes with the near-surface meridional flow. Standard thin flux tube simulations indicate that the radial gradient of differential rotation ($\partialΩ/\partial r > 0$) breaks the spatial symmetry of emerging $Ω$-loops. The leading (western) leg becomes nearly vertical, while the trailing (eastern) leg is heavily stretched and flattens along the longitude. Upon emergence at the photosphere, t…

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astro-ph.GA

Black Hole-Galaxy Correlations in Cluster Zoomed-in Simulations: GIZMO-SIMBA and TNG-Cluster

Hangxin Pu, Antonios Katsianis, Weiguang Cui, Romeel Davé, Massimo Gaspari, Weishan Zhu, Xiaohu Yang, Jinyi Shangguan et al.

We investigate the co-evolution of supermassive black holes (SMBHs) and central galaxies in massive clusters using the GIZMO-SIMBA and TNG-Cluster zoom-in simulations at $z=0-5$. We find that the distinct subgrid physics of these two models suggest fundamentally different evolutionary pathways. On the one hand, GIZMO-SIMBA, employs torque-limited accretion and predicts a supply-driven scenario where the SMBHs rapidly assemble synchronized with dark matter halo ($M_{200c}$) growth (i.e. the halo…

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astro-ph.COastro-ph.IM

SMART : Spherical Mass ApeRture Toolkit

Igor Bezmaternykh, Sandrine Pires, Nicolas Dagoneau, Gabriel W. Pratt, Loris Chappuis, Gavin Leroy

The aperture mass filter is a widely used tool in weak lensing studies. While previous surveys have typically relied on the flat-sky approximation, forthcoming Stage IV surveys such as Euclid will cover sufficiently large areas to require the construction of curved-sky aperture mass maps. In this paper, we extend the shear-based aperture mass formalism to the sphere and introduce a software package for a fast and precise computation of spherical aperture mass maps from the shear field, defined d…

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astro-ph.IM

The EDD Radio Astronomy Backend Framework

Ewan D. Barr, Amit Bansod, Jan Behrend, Weiwei Chen, Niclas Esser, Yungpen Men, Tobias Winchen, Jason Wu et al.

Modern digital radio astronomy receivers produce increasingly wide-bandwidth, high bit-rate data streams that necessitate the development of flexible, scalable, and maintainable backend processing and recording systems. Historically, such backend instrumentation has been tightly coupled to telescope observing modes, limiting reuse between observatories and science cases. We present the Effelsberg Direct Digitisation (EDD) backend framework, a software-defined architecture for constructing real-t…

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astro-ph.IMastro-ph.EPq-bio.PE

A Framework for Evaluating Forward Contamination Risk for Bio-ISRU Microorganisms

Una Nattermann, Devon A. Stork, Tom Pedersen, Nathan D. Hicks, Jordan E. Mancuso, Keren Isaev, Max G. Schubert, Fatima R. Martin et al.

NASA planetary protection policy seeks to avoid inadvertent forward contamination of celestial bodies and backward contamination of Earth during space exploration. For Mars missions, it has historically focused on sterilization of landers and rovers. Current policy provides no framework for assessing the forward contamination risk of missions that deliberately include living organisms and must not be sterilized, such as a human crew, agriculture, or biotechnology for manufacturing and life suppo…

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astro-ph.SR

Statistical evidence for linear combination frequencies in γ Doradus stars being nonlinear resonant modes

Yanqi Mo, Weikai Zong, Xuan Wang, Jian-Ning Fu, Xiao-Yu Ma, Mingfeng Qin, Stéphane Charpinet

The quest for the origin of linear combination frequencies in pulsating stars is critical for mode identification and subsequent seismic modeling. Hybrid γ Doradus (Dor) stars provide a crucial testbed for such investigations due to their rich frequency content in both gravity (g) and pressure (p) modes. Here, we performed a comprehensive survey of 608 Kepler γ Dor stars, detecting 81,265 frequencies, and identifying 1,895 harmonics and 45,968 combinations involving two parent frequencies. Our r…

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astro-ph.GA

Nitrogen-Loud Quasars from the Dark Energy Spectroscopic Instrument. I. Sample Selection and Basic Properties

Shuo Zhai, Wei-Jian Guo, Yong-Jie Chen, Zhi-Qiang Chen, Haining Li, Jian-Min Wang, Gang Zhao

We present the largest sample to date of nitrogen-loud (N-loud) quasars with strong broad N IV] $\lambda1486$ and/or N III] $\lambda1750$ emission lines over the redshift range $1.6 < z < 4.3$, selected from the Dark Energy Spectroscopic Instrument (DESI) Data Release 1. The final sample contains 1,993 N-loud quasars, corresponding to about 1.2% of the parent quasar sample. The $L_{1450}$ distribution of the N-loud quasars is broadly similar to that of the DESI parent sample, but their redshift…

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astro-ph.IMastro-ph.HE

Astrophysics in the Era of Artificial Intelligence powered by Large Language Models

A. R. Rao

In recent times there is considerable unease about the way Artificial Intelligence (AI) powered by large language models is used to do astrophysics, and, assuming that these AIs will get far better in future, several alarming situations are also discussed. In a ``white paper,'' Hogg argues that extreme cases like allowing AI to write all astrophysics papers or strictly controlling AI are not good choices and posits that it is difficult to adopt moderate policies. I examine the impact of AI on as…

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astro-ph.GA

SPURS: An Ultra-deep View Inside the Compact, Nitrogen-Enriched Nuclei of Little Red Dots

Mengtao Tang, Daniel P. Stark, Charlotte A. Mason, Zuyi Chen, Tucker Jones, Sarah Searle Grannis, Peter Senchyna, Lily Whitler et al.

We present the first ultra-deep rest-UV spectroscopy of four UV-bright Little Red Dots (LRDs), obtained from the SPURS Cycle 4 Large Program. The spectra reveal broad CIV (FWHM $\approx2700-2800$ km s$^{-1}$) in two LRDs, alongside narrow-line densities elevated above star-forming galaxies ($n_e\sim10^4-10^5$ cm$^{-3}$, reaching $10^6$ cm$^{-3}$ in the most extreme source) and nitrogen-enhancements in all four LRDs. We detect broad HeII emission (FWHM $\approx930$ km s$^{-1}$) in one LRD, and tw…

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astro-ph.HEastro-ph.SR

Evidence for the binary nature of the long-period radio transient ASKAP/DART J1832-0911

Csanád Horváth, Natasha Hurley-Walker, Ziteng Wang, Andrew Zic, Emil Lenc

Long-period transients are a class of periodic pulsed radio source repeating on the minute to hour timescale. Recently, an increasing number of them are being identified as binary systems, specifically white dwarfs with low-mass main-sequence companions. In this work we analyse the most luminous long-period transient discovered to date, ASKAP/DART J1832-0911, with two years of radio data, and propose that it, too, may be a white dwarf system, although in a far more compact orbit than the aforeme…

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astro-ph.SRastro-ph.GA

Uncovering the Origin of Slow Rotators among Intermediate-Mass Stars in the Star-Forming Cluster Trumpler 14

Khushboo K. Rao, Wen-Ping Chen, Hsiang-Yu Chen, Kristen Dage, Stella S. R. Offner

Intermediate-mass (about 1.5-8 M$_{\odot}$) stars exhibit a wide range of rotation rates and have gained attention for their roles in the extended main-sequence turnoffs (eMSTO) seen in some young and intermediate-age clusters (ages $< 2$ Gyr). Although rapid rotation is expected due to their radiative envelopes, the presence of slow rotators remains puzzling. In this study, we examine disk and X-ray signatures among the intermediate-mass members of the star-forming cluster Trumpler 14. Of the 1…

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