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Research Trends

Latest preprints in space engineering and astrophysics.

astro-ph.GAastro-ph.IM

Investigations of MWISP Bubbles: Identification and Analysis of Enclosed Molecular Bubbles by Weight Fields

Yu Jiang, Xuepeng Chen, Ji Yang, Ke Wang, Zhibo Jiang, Sheng Zheng, Yan Sun, Yang Su et al.

Molecular bubbles are widely used as tracers of stellar feedback; yet, their identification in spectral-line surveys remains challenging because both cavity morphology and kinematic structure must be assessed consistently in position--position--velocity (PPV) space. We present the Bubble-Weight Fields (BWFields) framework, a PPV-based method that for the first time enables the automated and objective identification and analysis of enclosed molecular bubbles directly from spectral-line data cubes…

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astro-ph.HE

Day-timescale Quasi-periodic Oscillations of the Gev BL Lac RX J0805.4+7534 with TESS

Xin-Shun Jin, Ting-Feng Yi, Yangwei Zhang, Yuncai Shen, Junjie Wang, Lisheng Mao, Liang Dong

This paper reports for the first time the detection of quasi-periodic oscillations (QPOs) in the light curves of the BL Lacertae object RX J0805.4+7534. The Transiting Exoplanetary Survey Satellite (TESS) observed this source in seven sectors of the sky, and we extracted the light curves for these sectors using a custom method. The presence of QPO signals was found in these light curves. To detecte the periodicity and assess the statistical significance of the QPO signals, we employed two method…

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astro-ph.HE

Radio-Gamma-Ray Properties and High-Energy Implications for Fermi Blazars

Xu-Hong Ye, Wen-Xin Yang, Guo-Hai Chen, Zhi-Yuan Pei, Yong-Yun Chen, Yi Liu, Denis Bastieri, Jun-Hui Fan et al.

Radio and $γ$-ray emissions in blazars, a subclass of active galactic nuclei (AGNs), provide important insight into their high-energy radiation processes. We studied the relation between radio and $γ$-ray emissions using a large sample of 1687 \textit{Fermi} blazars, based on the Radio Fundamental Catalogue and the latest Third Data Release of the Fourth \textit{Fermi} AGN Catalogue. A clear correlation between radio and $γ$-ray fluxes for both BL Lacertae objects (BL Lacs) and flat-spectrum rad…

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astro-ph.EP

Öpik-type collision frequency for Kozai-driven projectiles: Target bodies on inclined circular orbits

Youpeng Liang, Junhai Huang, Xiaodong Liu

Existing Öpik-type collision-frequency methods already incorporate the Kozai-driven secular evolution of the orbital elements of high-inclination projectiles. However, these methods generally assume that the target body's orbit lies in the reference plane defined by the orbital plane of the perturbing body. The present paper extends the semi-analytical framework developed by Vokrouhlický et al. (2012) for a target body on a circular orbit in the reference plane to the case of a target body on a…

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astro-ph.GA

VLT/MUSE Study of Close AGN Pairs and Host Galaxies in the Local Universe. I. Overview of the Ionized Gas

Xiaoyu Xu, Zhiyuan Li, Meicun Hou, Junfeng Wang, Fuyan Bian, Yan-Mei Chen

Studying AGN pairs and their host galaxies is essential for understanding the interplay between galaxy mergers and key internal processes such as supermassive black hole fueling and feedback. We cross-match between the Big Multi-AGN Catalog (The Big MAC) and the public data archive of the VLT/MUSE, and obtain 12 AGN pair candidates in the local universe ($z\lesssim0.1$) with a projected distance $r_{\rm p}\leq 20\rm\,kpc$. Using the archival VLT/MUSE data, we present a spatially resolved study o…

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astro-ph.SR

First monitoring campaign of a Main-sequence Radio Pulse emitter: the case of CU Vir

Barnali Das, Hayley Bignall, Andrew Zic, Poonam Chandra, Joshua Pritchard, John Morgan, Ankita Ghosh, Bhaswati Bhattacharyya et al.

CU Vir, a magnetic hot star, is the first discovered Main-sequence Radio Pulse emitter (MRP) characterized by its ability to produce periodic radio pulses via electron cyclotron maser emission. Although significant advancements have been made in understanding MRPs, their temporal properties remain mostly unexplored. To overcome this limitation, we conducted a pilot study with the Australia Telescope Compact Array, in which we observed pulses from CU Vir at 36 epochs over $1-3$ GHz. In this frequ…

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gr-qcastro-ph.HE

Unified remnant models for aligned-spin, precessing, and eccentric binary black hole mergers

Tousif Islam, Digvijay Wadekar, Gaurav Khanna

Using approximately $5000$ numerical-relativity (NR) simulations spanning mass ratios up to $q=128$ and $1200$ black-hole-perturbation-theory (BHPT) simulations extending to $q=1000$, we present fully analytic models for the remnant properties of quasi-circular binary black hole mergers. The models gwModelRemS (for final mass, final spin, peak luminosity, and recoil kick) and gwModelRemP (for final mass, final spin, and peak luminosity) describe nonprecessing and precessing binaries, respectivel…

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astro-ph.COastro-ph.HEhep-exhep-ph

Measurement of the Hubble constant with high-energy neutrinos

Gonzalo Herrera, Nicholas Kamp, Carlos A. Argüelles

Measuring distances in the Universe is one of the hardest problems in physics and astronomy. Almost every distance probe relies on photons, whose propagation across cosmic distances introduces extinction, absorption, scattering, and radiative-transfer effects. Neutrinos suffer none of these and propagate unattenuated through dust, intergalactic medium, and dense source environments alike. We introduce a new distance-ladder method for measuring the Hubble constant $H_0$ using high-energy astrophy…

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astro-ph.GA

The HII Regions' Molecular Law of Star Formation

Daniela Calzetti, Drew Lapeer, Robert C. Kennicutt, Bruce Elmegreen, Sean T. Linden, Mark R. Krumholz, Angela Adamo, Daniel A. Dale et al.

We combine imaging data from the HST, JWST, and ground-based millimeter facilities to investigate the correlation between star formation rate (SFR) and molecular gas at the ~100 pc scale of HII regions in three nearby galaxies: NGC628, NGC5194 and NGC5236. The JWST 21 micron maps of the three galaxies offer a unique insight into the dust-absorbed SFR at high resolution. We find that the relation between the surface densities of SFR and molecular gas has a slope of ~1.85, in log-log scale, signif…

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astro-ph.IMastro-ph.HE

Black Hole Explorer Mission Development in Japan

Kazunori Akiyama, Mareki Honma, Akihiro Doi, Shoko Koyama, Kotaro Niinuma, Kazuhiro Hada, Yuto Akiyama, Rebecca Baturin et al.

The Black Hole Explorer (BHEX) is a next-generation space very-long-baseline interferometry (VLBI) mission concept that will extend existing ground-based millimeter/submillimeter VLBI arrays to space. The Japanese astronomical community has contributed to BHEX mission development through the BHEX Japan Consortium, established in 2023. This paper provides a high-level summary of progress in Japan since 2024, including the establishment of the Black Hole Explorer Working Group (BHEX WG) at the Ins…

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hep-phastro-ph.HE

Scalaron-driven Dark Matter during Warm Inflation via UV Freeze--in

F. Millo

We investigate the production of Dark Matter (DM) within the warm Higgs--Starobinsky (HS) inflation. By adopting the ultraviolet (UV) freeze--in mechanism -- where the DM number density is initially negligible but is populated over time through non-renormalizable interactions of defined mass dimensions -- we find that the DM production within the HS potential has a characteristic timing. For both DM masses, $m_χ=1$ MeV and $m_χ=100$ GeV, the yield of DM occurs close to the termination of inflati…

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astro-ph.IMphysics.optics

Qualification pathways for Photonic Integrated Circuits in Astrophotonic Space Missions

Kalaga Madhav, Aashia Rahman, Máté Ádámkovics

Photonic integrated circuits (PICs) promise order-of-magnitude reductions in the size, weight and power (SWaP) of optical subsystems for astronomy, planetary and Earth-observation missions, yet no PIC-specific space-qualification standard exists. This paper consolidates the principal NASA and ESA qualification documents that apply, or can be tailored, to astrophotonic PICs --- arrayed waveguide gratings, photonic lanterns, fibre Bragg gratings, and integrated beam combiners (ABCD, discrete beam…

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astro-ph.IMastro-ph.SR

webSME: An online tool to infer stellar parameters and abundances

Johannes Puschnig, Andreas J. Korn, Jonathan Remmert, Ivy Balkwill-Western, Chi Than Nguyen, Nikolai Piskunov

Stellar spectroscopy is a robust technique for determining fundamental stellar parameters such as effective temperature, surface gravity and metallicity. Spectroscopy Made Easy (SME) has long served as a framework for spectral synthesis and parameter inference. In this paper, we introduce webSME, a web-based extension of the Python implementation of SME. webSME integrates enhancements including a non-local thermodynamic equilibrium abundance correction mode, a precomputed grid of synthetic spect…

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astro-ph.HE

Submillimeter Detectability of Gravitational-Wave Counterparts from Neutron-Star Mergers with the Xue-shan-mu-chang 15-meter Telescope

Di Xiao

Submillimeter (sub-mm) follow-up of binary neutron star (BNS) mergers provides unique constraints on the early-time energetics and environments of relativistic outflows, capturing the spectral evolution at epochs where centimeter-band emission is often still optically thick or yet to peak. However, the practical scientific yield depends on instrument-specific thresholds, the observing cadence, and the distinct temporal contributions from isotropic ejecta versus beamed relativistic jets. With the…

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astro-ph.IM

Conceptual architecture of the detector infrastructure for WST

A. Meoli, O. Iwert, E. George, O. Squalli, M. Richerzhagen, A. Rüde, M. Seidel, S. Lévêque et al.

The Wide-field Spectroscopic Telescope (WST) is a proposed 12 m wide-field spectroscopic facility combining several multi-object spectrographs. It requires a yet unprecedented number of detectors. In this paper we present conceptual architecture for the detector controller and infrastructure required to operate a large number of detectors, potentially applicable to WST, focusing on the system-level, power distribution, and the associated data handling. We also consider how these elements may evo…

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astro-ph.GA

Supernova feedback in porous photoionized Giant Molecular Clouds

Cheryl S. C. Lau, Ian A. Bonnell, Yueh-Ning Lee, Ke-Jung Chen

We present a new suite of numerical simulations of Type II supernovae (SNe) detonating in Giant Molecular Clouds with a variety of density structures shaped by photoionization feedback. Ionizing radiation sculpts cavities and channels that guide SN energy to emerge from the cloud as shock-driven blowouts, rather than as a coherent spherically expanding shell as assumed in most sub-grid SN models adopted in galaxy or cosmological simulations. We investigate how such outflows differ to the 1-D des…

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astro-ph.GAastro-ph.SR

Spectral Microlensing of Extragalactic H II Regions by Stellar-Mass Black Holes

Dezi Liu

Most of the Milky Way's predicted stellar-mass black holes remain hidden, especially at high Galactic latitudes or in the Galactic halo, where traditional dense-field stellar microlensing is ineffective. We propose an alternative method to map this isolated population via the spectral microlensing of compact, extragalactic H II regions. Projected onto the source plane, the physical Einstein radius of a Galactic black hole can match the typical core sizes of H II regions in distant galaxies. Micr…

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

ESCAPE: a small explorer mission to study the stellar drivers of exoplanet evolution

Allison Youngblood, Kevin France, Brian Fleming, Tim H. Hellickson, Alan C. Hoskins, James Paul Mason, Dolon Bhattacharyya, Hannah Diamond-Lowe et al.

The long-term stability of exoplanetary atmospheres depends critically on the extreme-ultraviolet (EUV) photon and high-energy particle fluxes from the host star, which are poorly constrained. To address this key gap in our understanding of atmospheric retention, we present the Extreme-ultraviolet Stellar Characterization for Atmospheric Physics and Evolution (ESCAPE) mission, a NASA Small Explorer concept proposed in 2026. ESCAPE employs extreme- and far-ultraviolet spectroscopy (80 - 1650 Ang)…

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astro-ph.HEastro-ph.GA

Evidence for a bursty $γ$-ray QPO in the neutrino-associated FSRQ PKS 1424$-$418 using Fast Template Periodograms and Machine Learning

Aaron A. Maldonado, Alberto Domínguez, Adithiya Dinesh, Alba Rico, Pablo Peñil, Sara Buson, Marco Ajello

Standard frequency-domain searches for quasi-periodic oscillations (QPOs) in active galactic nuclei generally assume sinusoidal variability. However, $γ$-ray blazar emission often shows asymmetric flares and localized bursts, causing spectral leakage that can reduce the sensitivity of conventional methods to non-sinusoidal periodic signals. We analyze a blind sample of 100 high-cadence (7-day binned) Fermi-LAT blazar light curves. After baseline detrending with Singular Spectrum Analysis, we app…

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astro-ph.GA

Formation of extragalactic Star Clusters

Gerhard Hensler, Yannick Hein, Alessandro Boselli, the VESTIGE consortium

The outskirts of galaxies show their beauty by an assembly of Globular Clusters and satellite galaxies, but also by interactions with their environment. Galaxies in clusters experience dynamical effects by mutual encounters and by the intra-cluster gas. This latter exerts a drag to remove gas from the outskirts. These stripped clouds are capable to form stars and open fundamental questions on astrophysical processes, as e.g. the survival of intergalactic clouds, the star-formation process, the e…

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astro-ph.HEastro-ph.GA

Metal sign of a large-scale AGN feedback in cool-core cluster MACS J1931.8-2634

Qinnan Zhu, Junjie Mao, Ping Zhou, Yuanyuan Su, Dan Hu

The spatial distribution of metals in the intracluster medium (ICM) is a sensitive tracer of the chemical and dynamical history of galaxy clusters. While most cool-core (CC) clusters exhibit a centrally peaked Fe abundance profile, several outliers show an anomalous central Fe drop, potentially associated with the AGN activities. We revisit the reported large-scale (sim 100 kpc) central Fe drop in the massive CC cluster MACS J1931.8-2634 using new XMM-Newton observations. We aim to verify this f…

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astro-ph.SR

Three-dimensional Magnetic Structures of Ellerman Bombs revealed by SUNRISE III/SCIP

Yusuke Kawabata, Yukio Katsukawa, Masahito Kubo, Takayoshi Oba, Takuma Matsumoto, Ryohtaroh T. Ishikawa, Yoshihiro Naito, Hirohisa Hara et al.

Ellerman bombs (EBs) are widely recognized as photospheric and chromospheric signatures of magnetic reconnection. However, the three-dimensional (3D) magnetic topology has remained elusive due to the lack of seamless height coverage in observations. Here, we present initial results from the SUNRISE III/SCIP (Sunrise Chromospheric Infrared spectroPolarimeter) observations of an emerging flux region. Exploiting the seeing-free, high-spatial-resolution observations provided by the 1-meter balloon-b…

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astro-ph.HEhep-ph

Gamma Rays from ALP-Photon Conversion and Inverse Compton Reprocessing in Neutron Star Magnetospheres

Federica Giacchino, Conrado A. Torres, Giorgio Galanti, Bradley J. Kavanagh, Maria A. Pérez-García, Jose M. Diego

Exploring axion-like particle (ALP) signatures from neutron stars (NSs) in the \emph{Fermi}-LAT energy range remains largely unexplored. Neutron stars with exceptionally strong magnetic fields, such as magnetars and pulsars with magnetar-like magnetic fields, provide particularly promising environments for ALP--photon conversion. Magnetars are characterized by surface magnetic fields as large as $B_0\sim(10^{14}$--$10^{15})\,\mathrm{G}$; however, despite their extreme magnetic fields, no steady…

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gr-qcastro-ph.HEhep-th

Evading Cauchy Horizon Excision in Scalarized Regular Black Holes

Ernesto Contreras, Pedro Bargueño, Arthur G. Suvorov

Spontaneous scalarization provides a dynamical mechanism to evade the no-hair paradigm, but it has been argued to generically eliminate the Cauchy horizon in charged black holes. We show that this obstruction is not universal, but instead follows from the sign-definite structure of the Einstein-Maxwell source term. Within the $P$-dual formulation of nonlinear electrodynamics, we derive a general condition under which the effective scalar source changes sign between the horizons, allowing the int…

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astro-ph.IM

Pollux: high-resolution precision spectroscopy and polarimetry for the Habitable Worlds Observatory

David Le Mignant, Coralie Neiner, Jean-Claude Bouret, Luca Fossati, Eduard Muslimov, Kjetil Dohlen, Anne Bonnefoi, Jean-Michel Reess et al.

Pollux is a high-resolution spectrograph and spectropolarimeter (R from 65000 to 100000) covering a spectral range from 100 nm to 1750 nm, proposed by a European consortium to equip NASA s Habitable Worlds Observatory (HWO). This instrument aims to revolutionize the study of stellar and (exo)planetary systems, as well as cosmic ecosystems, by combining high spectral resolution, broad and simultaneous spectral coverage, temporal stability, and unique UV spectropolarimetric capabilities, thus open…

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astro-ph.EPastro-ph.IM

Using High-Resolution Spectroscopy to Study the Composition, Temperature, and Dynamics of Exoplanet Atmospheres

Mu'allim Yakubu

High-resolution spectroscopy, typically operating at resolving powers R greater or equal to 25,000, has matured into one of the primary techniques for characterising the atmospheres of extrasolar planets. The ability of HRS to resolve individual rotational-vibrational lines of molecular bands, combined with the large Doppler shifts experienced by close-in planets during their orbits, allows planetary signals to be separated from quasi-stationary telluric and stellar contamination. Since the pion…

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astro-ph.IM

Development and Evaluation of a CNN-Based Charged-Particle Event Rejection Algorithm for Soft X-ray Detection in a pnCCD-Based Satellite System

Hsien-Chieh Shen, Ryuji Kondo, Makoto Arimoto, Tatsuro Kanenaga, Hiro Otsuka, Shutaro Ueda, Junko Hiraga, Daisuke Yonetoku et al.

All-sky surveys in the soft X-ray band are essential for detecting transient objects such as high-redshift gamma-ray bursts (GRBs), which provide key insights into the early universe. HiZ-GUNDAM is a future satellite mission designed to detect and localize high-redshift GRBs. Its wide-field X-ray monitor, EAGLE, combines Lobster Eye Optics with a pnCCD imaging detector operating in the 0.4-4 keV band. Because of limited satellite telemetry, full-frame pnCCD images cannot be downlinked, requiring…

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astro-ph.GA

Hub-filament systems and the growth of massive stars: episodic accretion, clustered environments, and projection effects

Dana Makarova, Dana Alina, Paolo Padoan, Baurzhan Kumarioldanov, Mika Juvela, Dilda Berdikhan, Naval Bhadari

The processes controlling the early mass growth of future massive stars remain poorly understood, particularly the connection of this growth to star clustering and hub-filament systems (HFSs). This connection is difficult to establish observationally, because projection effects and line-of-sight confusion in position-position-velocity (PPV) data can distort the information about the intrinsic filamentary structure. To investigate this connection, we used a three-dimensional magnetohydrodynamic (…

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astro-ph.SR

Solar Orbiter SEP Dropout during a Magnetic Cloud with Evidence for Strong Connectivity Gradients

Radoslav Bucik, Raul Gomez-Herrero, Samuel T. Hart, Maher A. Dayeh, Nariaki V. Nitta

We analyze an impulsive solar energetic particle (SEP) event observed by Solar Orbiter at 0.93 au on 2022 December 24 that exhibits a pronounced intensity dropout between approximately 07:15 and 10:00 UT. Pitch-angle distributions show a near-field-aligned beam before the dropout, which disappears abruptly at the dropout onset. At the same time, a weak 100--200 keV component appears at pitch angles of about 90--180 degrees; no comparable enhancement over this pitch-angle range is present at MeV…

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