Current date: 2025-10-10
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Number of records retrieved: 802
Keyword score statistics
score 13 -- 1 abstracts
score 7 -- 1 abstracts
score 6 -- 1 abstracts
score 5 -- 4 abstracts
score 4 -- 3 abstracts
score 3 -- 4 abstracts
score 2 -- 15 abstracts
in total -- 29 abstracts
Articles that appeared on 2025-10-10
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[abstract 1 / 29] Wow! (score: 13)
- Title: Hunting Very High-Energy ($>$100 GeV) Emitting High-Synchrotron Peaked BlazarsAuthors: Sushmita Agarwal, Vaidehi S. Paliya,Comments: 12 pages, 6 figures, 5 table, Submitted in ApJS. DOI for catalog: https://doi.org/10.5281/zenodo.17219533Subjects: astro-ph.HECreated: 2025-10-09; Updated: 2025-10-10; Datestamp: 2025-10-10
Very-high energy (VHE; $>$100 GeV) $γ$-ray emission originates via some of the most extreme particle acceleration processes in the universe. Considering beamed ACTIVE GALACTIC NUCLEi, i.e., BLAZARs, only a small fraction, mainly high SYNCHROTRON peak BL Lacs, have been detected in the VHE band with the ground-based Cherenkov telescopes. We utilized $\sim$16 years of FERMI-Large Area Telescope (LAT) observations in the 0.1$-$2 TeV energy range to systematically search for potential VHE emitters in a sample of high SYNCHROTRON peaked ($ν^{\rm peak}_{\rm syn}>10^{15}$ Hz) BL Lac sources. We identified, for the first time, 92 VHE emitting BLAZARs at $\geq 5σ$ confidence level. A significant VHE emission was also detected from 52 objects, which have been previously reported to be a VHE BLAZAR. Comparing with the general BLAZAR population, these VHE emitting BLAZARs are found to be located at low redshifts (mean $z=0.2 \pm 0.1$) and exhibit bright SYNCHROTRON emission ($\log F^{\rm peak}_{\rm syn}=-11.2 \pm 0.4$, in erg cm$^{-2}$ s$^{-1}$). We also investigated the coincidence of VHE photon arrivals with the source activity states and found that FERMI-LAT has detected VHE photons during both quiescent and elevated activity epochs. These VHE emitting BLAZARs represent promising targets for current and next-generation ground-based Cherenkov telescopes, and provide valuable laboratories for probing particle acceleration in RELATIVISTIC JETs, testing multi-messenger connections, and constraining extragalactic background light models.
[abstract 2 / 29] Wow! (score: 7) - Title: The very high energy view of GAMMA-RAY BURSTs with the MAGIC telescopesAuthors: Alessio Berti, Željka Bošnjak, Alberto Castro-Tirado, Stefano Covino, Susumu Inoue, Francesco Longo, Serena Loporchio, Davide Miceli, Razmik Mirzoyan, Elena Moretti, Lara Nava, Koji Noda, David Paneque, Antonio Stamerra, Yusuke Suda, Kenta Terauchi, Ievgen Vovk, Katsuaki Asano, Satoshi Fukami, Nuria Jordana-Mitjans, Andrea Melandri, Carole Mundell, Michele Palatiello, Manisha Shrestha, Iain Steele,Comments: Proceedings of the ICRC 2025Subjects: astro-ph.HECreated: 2025-10-09; Updated: 2025-10-10; Datestamp: 2025-10-10
Gamma-ray bursts (GRBs) are one of the main targets for the observations of the MAGIC telescopes. As a result of the effort in improving the sensitivity of the instrument and the automatic follow-up strategy, MAGIC detected two GRBs in the very-high-energy (VHE, $E>100$ GeV) range, namely GRB 190114C and GRB 201216C. In GRB 190114C ($z=0.42$), the data collected by MAGIC revealed a new emission component at sub-TeV energies in the afterglow of the GRB. The very rich multi-wavelength dataset, spanning 17 orders of magnitude in energy, allowed to perform a detailed modelling of the broadband emission. The multi-wavelength data could be modelled within a one-zone SYNCHROTRON-self Compton scenario with internal $γ-γ$ absorption, where the model parameters are compatible with those found in previous GRB afterglow studies below GeV energies. Similarly, GRB 201216C broadband emission could be explained using the same model, although the amount of simultaneous multi-wavelength data is reduced with respect to GRB 190114C. In particular, GRB 201216C challenged the current MAGIC detection potential, as its redshift was determined to be $z=1.1$, strongly reducing the observed gamma-ray flux but making it the most distant source detected at VHE. These two detections, accompanied by evidence of VHE emission from a few more GRBs, opened up new questions such as the presence of sub-TeV emission in different classes and phases of GRBs. In this contribution we will present the status of the MAGIC GRB follow-up program, with an highlight on its detected GRBs. Moreover we will show the results on the GRBs observed by MAGIC from 2013 to 2019 with no evidence of VHE emission, in particular for those with simultaneous X-ray observations and redshift $z<2$. We will discuss the implications of these results for GRB physics and the challenges and prospects for future GRB observations with MAGIC.
[abstract 3 / 29] Yes (score: 6) - Title: Extracting energy from plunging region of a Kerr-Taub-NUT BLACK HOLE by MAGNETic RECONNECTionAuthors: Zhengwei Cheng, Songbai Chen, Jiliang Jing,Comments: 21 pages, 9 figures, Accepted by EPJCSubjects: gr-qcCreated: 2025-10-09; Updated: 2025-10-10; Datestamp: 2025-10-10
We have studied the energy extraction from a Kerr-Taub-NUT BLACK HOLE via MAGNETic RECONNECTion occurring in the plunging region. Our results show that the gravitoMAGNETic charge suppresses the energy extraction process through MAGNETic RECONNECTion and reduces the corresponding extraction efficiency, which is opposite to the effects of the BLACK HOLE spin and the MAGNETization parameter. Finally, we treat the energy extraction process through MAGNETic RECONNECTion as a mechanism to revisit the problem of the observed JET power and radiative efficiency of GRS 1915+105. Our results show that the allowed BLACK HOLE parameter region originating from the JET power has an intersection with the region from the radiative efficiency. This means that with this mechanism related to MAGNETic RECONNECTion the Kerr-Taub-NUT metric can simultaneously explain the observed JET power and radiative efficiency for GRS 1915+105, which is not explained by other mechanisms in previous studies.
[abstract 4 / 29] Yes (score: 5) - Title: Does Turbulence at the Correlation Scale Regulate the Statistics of Magnetic Reconnection?Authors: M. B. Khan, M. A. Shay, S. Oughton, W. H. Matthaeus, C. C. Haggerty, S. Adhikari, P. A. Cassak, S. Fordin, D. O'Donnell, Y. Yang, R. Bandyopadhyay, S. Roy,Comments: Submitted to Physical Review LettersSubjects: physics.plasm-ph physics.space-phCreated: 2025-10-08; Updated: 2025-10-10; Datestamp: 2025-10-10
We study the statistics of dynamical quantities associated with MAGNETic RECONNECTion events embedded in a sea of strong background MAGNETohydrodynamic (MHD) turbulence using direct numerical simulations. We focus on the relationship of the RECONNECTion properties to the statistics of global turbulent fields. For the first time, we show that the distribution in turbulence of RECONNECTion rates (determined by upstream fields) is strongly correlated with the magnitude of the global turbulent MAGNETic field at the correlation scale. The average RECONNECTion rates, and associated dissipation rates, during turbulence are thus much larger than predicted by using turbulent MAGNETic field fluctuation amplitudes at the dissipation or kinetic scales. Magnetic RECONNECTion may therefore be playing a major role in energy dissipation in astrophysical and heliospheric turbulence.
[abstract 5 / 29] Yes (score: 5) - Title: Evidence for Supermassive Black Hole BinariesAuthors: Martin G. H. Krause, Martin A. Bourne, Silke Britzen, Adi Foord, Jenny E. Greene, Melanie Habouzit, Maya A. Horton, Lucio Mayer, Hannah Middleton, Rebecca Nealon, Julia M. Sisk-Reynés, Christopher S. Reynolds, Debora Sijacki,Comments: 20 pages, 8 figures, submitted to PASA, comments welcomeSubjects: astro-ph.HE astro-ph.GACreated: 2025-10-08; Updated: 2025-10-10; Datestamp: 2025-10-10
We review the state of the evidence for the existence and observational appearance of supermassive BLACK HOLE binaries. Such objects are expected from standard hierarchical galaxy evolution to form after two galaxies, each containing a supermassive BLACK HOLE, have merged, in the centre of the merger remnant. A complex interaction is predicted to take place with stars and gas in the host galaxy, leading to observable signatures in weakly as well as actively accreting phases. Direct observational evidence is available and shows examples of dual ACTIVE GALACTIC NUCLEi from kpc scales down to parsec scales. Signatures of possibly closer supermassive BLACK HOLE binaries may be seen in JETted BLACK HOLEs. The interaction with stars and gas in a galaxy significantly affects the hardening of the binary and hence contributes to uncertainties of the expected gravitational wave signal. The Laser Interferometer Space Antenna (LISA) should in the future detect actual mergers. Before the launch of LISA, pulsar timing arrays may have the best chance to detect a gravitational wave signal from supermassive BLACK HOLE binaries. The first signs of the combined background of inspiralling objects might have been seen already.
[abstract 6 / 29] Yes (score: 5) - Title: Two Possible Optical--X-Ray Anti-Correlations of PSR J1023+0038Authors: Ka-Yui Au, Kwan-Lok Li, Albert K. H. Kong, Jumpei Takata, Chung-Yue Hui, Lupin C. C. Lin,Comments: 21 pages, 15 figures, accepted by MNRASSubjects: astro-ph.HECreated: 2025-10-09; Updated: 2025-10-10; Datestamp: 2025-10-10
X-ray emission is generally believed to be one of the major heating sources for the optical modulation in redback pulsar binaries as we have seen similar phenomena in many low mass X-ray binaries (LMXBs). While, e.g., MeV/GeV gamma-rays from the neutron stars are also possible heating sources, X-ray observations are currently much more sensitive, and therefore, joint optical--X-ray data are observationally unique on the irradiation mechanism investigation. Using 18 X-ray/B-band simultaneous XMM-Newton observations (717 ks in total) of the redback system PSR J1023+0038 taken during the LMXB state, we find a general trend that the amplitude of the B-band orbital modulation was lower when the observed X-ray flux was higher. Depending on the analysis method adopted, the statistical significance of the anti-correlation can be from 1.7sigma to 3.1sigma. We also extended the analysis to the GeV gamma-ray band using the FERMI-LAT data, but the result is insignificant to claim any relations. Moreover, another X-ray/optical correlation regarding the low modes of the system was found in some of the \textit{XMM-Newton} observations, and the astrophysical reason behind is currently unclear yet. These anti-correlations likely suggest that the irradiation is generally stronger when the X-ray flux is in a fainter state, indicating that there is a more dominant irradiation source than the X-ray emission.
[abstract 7 / 29] Yes (score: 5) - Title: Acceleration of Ultrahigh Energy Particles from Fast Radio BurstsAuthors: Lin Yu, Tianxing Hu, Zhiyu Lei, Dong Wu, Suming Weng, Min Chen, Jie Zhang, Zhengming Sheng,Comments:Subjects: astro-ph.HECreated: 2025-10-09; Updated: 2025-10-10; Datestamp: 2025-10-10
Two extreme events in the universe, fast radio bursts (FRBs) and COSMIC RAYs (CRs), could be corelated, where FRBs with extreme field strength near their sources may contribute to CRs. This study investigates localized particle acceleration driven by FRB-like ultra-RELATIVISTIC electroMAGNETic pulses. It is found ultra-high energy neutral plasma sheets form constantly via the front erosion of an FRB pulse. There are two ion acceleration regimes depending upon the field strength and the plasma density: the wakefield regime dominated by charge separation fields, and the piston regime driven by the $\mathbf{V}\times\mathbf{B}$ force of the pulses. The predicted energy scalings align well with particle-in-cell simulations. A power-law energy spectrum naturally arises with an index close to the CRs during FRB diffusion outward. Joint observations of FRBs and CRs may provide an opportunity to understand these extreme events and advance the development of multi-messenger astronomy.
[abstract 8 / 29] Yes (score: 4) - Title: Tidal disruption events in ACTIVE GALACTIC NUCLEi: on orbital inclination and Schwarzschild apsidal precessionAuthors: Minghao Zhang, Wenda Zhang, Hongping Deng, Hengxiao Guo, Jingbo Sun,Comments: 27 pages, 16 figures, 2 tables, accepted for publication in ApJSubjects: astro-ph.HECreated: 2025-10-09; Updated: 2025-10-10; Datestamp: 2025-10-10
Tidal disruption events (TDEs) in ACTIVE GALACTIC NUCLEi (AGNs) mark a regime where traditional vacuum models fail to capture the full dynamics, especially due to interaction between stellar debris and pre-existing accretion disks. We perform meshless hydrodynamic simulations incorporating both general RELATIVISTIC (GR) effects and radiative cooling to study TDEs in AGNs with different orbital inclinations ($θ_{\rm inc}$) of the disrupted star, ranging from projected prograde to retrograde orbits. We post-process the simulations to derive multi-wavelength light curves and identify several distinct features in the light curves, including a precursor flare from early debris-disk collision and a major flare driven by fallback. The dynamics of the stellar debris and accretion disk, and subsequently the light curve features, are strongly affected by $θ_{\rm inc}$ and GR effects. Retrograde orbits ($θ_{\rm inc}=135^\circ$) yield a more luminous, shorter major flare and a more prominent precursor than prograde ones ($θ_{\rm inc}=22.5^\circ$). During fallback, prograde cases ($θ_{\rm inc} = 22.5^\circ$, $45^\circ$) develop a central cavity with spirals in the inner region of the AGN disk, leading to transient UV/X-ray suppression accompanied by oscillations, while higher inclinations ($θ_{\rm inc}=90^\circ$, $135^\circ$) form a gradually tilting inner disk, potentially causing UV/X-ray dips via geometric effects at certain viewing angles. Relativistic apsidal precession alters stream collisions, producing structural differences in the inner disk, outer disk, and debris compared to Newtonian cases, and drives quasi-periodic signals in prograde configurations. These results provide predictive diagnostics for identifying AGN TDEs and interpreting observed light-curve diversity.
[abstract 9 / 29] Yes (score: 4) - Title: XRISM/Resolve observations of Hercules X-1: vertical structure and kinematics of the disk windAuthors: Peter Kosec, Laura Brenneman, Erin Kara, Teruaki Enoto, Takuto Narita, Koh Sakamoto, Rudiger Staubert, Francesco Barra, Andrew Fabian, Jon M. Miller, Ciro Pinto, Daniele Rogantini, Dominic Walton, Yutaro Nagai,Comments: To be submitted. 19 pages, 8 figures, 5 tablesSubjects: astro-ph.HECreated: 2025-10-08; Updated: 2025-10-10; Datestamp: 2025-10-10
X-ray binary accretion disk winds can carry away a significant fraction of the originally infalling matter and hence strongly affect the accretion flow and the long-term evolution of the binary system. However, accurate measurements of their mass outflow rates are challenging due to uncertainties in our understanding of the 3D wind structure. Most studies employ absorption line spectroscopy that only gives us a single sightline through the wind streamlines. Hercules X-1 is a peculiar X-ray binary which allows us to avoid this issue, as its warped, precessing accretion disk naturally presents a range of sightlines through the vertical structure of its disk wind. Here we present the first results from a large, coordinated campaign on Her X-1 led by the new XRISM observatory and supported by XMM-Newton, NUSTAR and Chandra. We perform a time-resolved analysis and constrain the properties of the wind vertical structure. Thanks to the precision spectroscopy of XRISM/Resolve, we directly detect the Her X-1 orbital motion in the evolution of the outflow velocity. After correcting for this effect, we observe an increase in velocity from 250 km/s to 600 km/s as the wind rises to greater heights above the disk. The wind column density decreases with height, as expected, but its ionization parameter only evolves weakly, and is consistent with freezing out as the wind expands away. Additionally, we detect a new orbital dependence of the wind properties, revealing a likely second wind component that appears only briefly after the eclipse of Her X-1 by the secondary star.
[abstract 10 / 29] Yes (score: 4) - Title: Spin-Orbit Misalignments of Eccentric Black Hole Mergers in AGN DisksAuthors: Gaia Fabj, Christopher Tiede, Connar Rowan, Martin Pessah, Johan Samsing,Comments:Subjects: astro-ph.HE astro-ph.GACreated: 2025-10-09; Updated: 2025-10-10; Datestamp: 2025-10-10
The disks of ACTIVE GALACTIC NUCLEi (AGNs) provide a natural environment where stellar-mass BLACK HOLEs (BHs) can dynamically pair, undergo repeated interactions, and eventually merge. It is commonly assumed that gas accretion will both efficiently spin up disk-embedded BLACK HOLEs and align the orbits of embedded binaries with the disk plane, leading to mergers with preferentially positive effective spin parameters ($χ_{\mathrm{eff}}$). Such predictions have motivated the use of $χ_{\mathrm{eff}}$ as a diagnostic for identifying candidate AGN-embedded mergers in the LIGO-Virgo-KAGRA gravitational-wave catalog. In this work, we perform post-Newtonian $N$-body simulations of nearly planar binary-single encounters and apply an empirically motivated, gas-driven alignment prescription to characterize the expected $χ_{\mathrm{eff}}$-eccentricity correlations of AGN-embedded mergers. By comparing the alignment and gravitational-wave inspiral timescales, we identify the regions of parameter space, across both disk location and binary properties, where full disk-spin-orbit alignment is effective and where it is not. We find that quasi-circular binaries typically align by the time they merge, supporting the standard picture of spin-orbit aligned orientations. By contrast, eccentric binaries (with in-band eccentricity $e_{10\mathrm{Hz}}\gtrsim 0.1$) typically inspiral too quickly for gas torques to act, preserving the post-encounter spin-orbit misalignments and yielding more isotropic $χ_{\mathrm{eff}}$ distributions when disk densities and torque efficiencies are modest. This interplay naturally establishes a correlation between binary eccentricity and $χ_{\mathrm{eff}}$ in AGN disks, highlighting a new key observable of the AGN channel and a potential explanation for massive events such as GW190521 and GW231123.
[abstract 11 / 29] (score: 3) - Title: Cosmic-Ray Mass Composition around the Knee via Principal Component AnalysisAuthors: Nicusor Arsene,Comments: matches the published version in 'The Astrophysical Journal'Subjects: astro-ph.HECreated: 2025-10-09; Updated: 2025-10-10; Datestamp: 2025-10-10
In this paper, we apply Principal Component Analysis (PCA) to experimental data recorded by the KASCADE experiment to reconstruct the mass composition of COSMIC RAYs around the \textit{knee} region. A set of four extensive air shower parameters sensitive to the primary particle mass ($LCm$, $N_μ$, $N_{e}$, and lateral shower $age$) was considered, whose coordinates were transformed into a new orthogonal basis that maximally captures the data variance. Based on the experimental distributions of the first two principal components (PCA0 vs.\ PCA1) and full Monte Carlo simulations of the KASCADE array considering five types of primary particles (p, He, C, Si, and Fe) and three hadronic interaction models (EPOS-LHC, QGSJET-II-04, and SIBYLL~2.3d), we obtained the evolution of the abundance of each primary species as a function of energy, as well as the evolution of the mean logarithmic mass with energy. We found that the reconstruction of the mass composition resulting from this comprehensive analysis significantly reduces dependence on the hadronic interaction model used in the simulation process, even though the initial input parameters are model-dependent. Moreover, the results support the idea that around the \textit{knee} region, the abundance of the light component (protons) decreases, while the heavy component shows a slight increase. The evolution of $\langle \ln (A) \rangle$ as a function of energy derived from this analysis shows excellent agreement with recent results from the LHAASO--KM2A experiment and aligns very well with the predictions of the data-driven GSF model.
[abstract 12 / 29] (score: 3) - Title: Testing new-physics scenarios with the combined LHAASO and Carpet-3 fluence spectrum of GRB 221009A: axion-like particles and Lorentz-invariance violationAuthors: P. S. Satunin, S. V. Troitsky,Comments: 6 pages, 3 figures, JETP Letters styleSubjects: astro-ph.HE hep-phCreated: 2025-10-08; Updated: 2025-10-10; Datestamp: 2025-10-10
From GAMMA-RAY BURST (GRB) 221009A, very high-energy photons were detected: >10 TeV with LHAASO and >100 TeV with Carpet-3. Such energetic photons are expected to be absorbed via electron-positron pair production on their way to the Earth. Their observation might be explained by new physics, including Lorentz invariance violation (LIV) or photon mixing with axion-like particles (ALPs). Here, we construct a joint fluence spectrum by combining flux measurements from both experiments, and fit it under these hypotheses. LIV can account for the Carpet-3 observation, providing a modest improvement over standard physics in the overall fit. ALP mixing improves the description of both LHAASO and Carpet-3 data, yielding a substantial enhancement in fit quality for a specific region of the ALP parameter space.
[abstract 13 / 29] (score: 3) - Title: The $M_{\rm BH}-M_{*}$ Relationship at $3[abstract 14 / 29] (score: 3)Authors: Brenda L. Jones, Dale D. Kocevski, Fabio Pacucci, Anthony J. Taylor, Steven L. Finkelstein, Johannes Buchner, Jonathan R. Trump, Rachel S. Somerville, Michaela Hirschmann, L. Y. Aaron Yung, Guillermo Barro, Eric F. Bell, Laura Bisigello, Antonello Calabro, Nikko J. Cleri, Avishai Dekel, Mark Dickinson, Giovanni Gandolfi, Mauro Giavalisco, Norman A. Grogin, Kohei Inayoshi, Jeyhan S. Kartaltepe, Anton M. Koekemoer, Lorenzo Napolitano, Masafusa Onoue, Swara Ravindranath, Giulia Rodighiero, Stephen M. Wilkins,Comments: 20 pages, 9 figures, submitted to ApJSubjects: astro-ph.GACreated: 2025-10-08; Updated: 2025-10-10; Datestamp: 2025-10-10
JWST has identified a large population of faint, broad-line ACTIVE GALACTIC NUCLEi (AGN) in the early universe that are powered by BLACK HOLEs (BHs) that often appear overmassive relative to their host galaxies. In this study, we examine the relationship between BH mass and galaxy stellar mass at $3
arXiv:2510.08025 [pdf, ps, other]Astrophysical processes can contribute to MAGNETic fields within cosmic voids either through MAGNETized outflows from the astrophysical large-scale structure or through superposition of dipolar contributions from individual galaxies. Such astrophysical MAGNETic fields represent a foreground to possible space-filling primordial MAGNETic fields seeded in the early Universe. In this paper, we provide a qualitative description of the screening of MAGNETic fields by intergalactic plasmas. We find that contributions from superposition of static dipoles are highly suppressed and cannot explain indications for lower bounds based on observations of $γ$-ray cascades from high energy sources such as BLAZARs.
arXiv:2407.03828 [pdf, ps, other]We present a novel approach to investigating axions and axion-like particles (ALPs) by studying their potential conversion into X-rays within the Sun's atmospheric MAGNETic field. Utilizing high-sensitivity data from the Nuclear Spectroscopic Telescope Array (NUSTAR) collected during the 2020 solar minimum, along with advanced solar atmospheric MAGNETic field models, we establish a new limit on the axion-photon coupling strength $g_{aγ}\lesssim 7.3\times 10^{-12}$~GeV$^{-1}$ at 95\% CL for axion masses $m_a\lesssim 4\times 10^{-7}$\,eV. This constraint surpasses current ground-based experimental limits, studying previously unexplored regions of the axion-photon coupling parameter space up to masses of $m_a\lesssim 3.4\times 10^{-4}$\,eV. These findings mark a significant advancement in our ability to probe axion properties and strengthen indirect searches for DARK MATTER candidates.
arXiv:2503.11139 [pdf, ps, other]We investigate the relationships between the cool circumgalactic medium (CGM), traced by Ca II absorption lines, and galaxy properties at $z<0.4$ using $\sim900{,}000$ galaxy-QUASAR pairs within $200\,\rm kpc$ from the Year 1 data of the Dark Energy Spectroscopic Instrument (DESI). This large data set enables us to obtain composite spectra with sensitivity reaching to the $\text{mÅ}$ level and to explore the Ca II absorption as a function of stellar mass, STAR FORMATION rate (SFR), redshift, and galaxy types, including ACTIVE GALACTIC NUCLEi (AGNs). Our results show a positive correlation between the absorption strength and stellar mass of star-forming galaxies with $\langle W_{0}^{\rm Ca\ II}\rangle \propto M_{*}^{0.5}$ over 3 orders of magnitude in stellar mass from $\sim 10^{8}$ to $10^{11} \, M_{\odot}$, while such a mass dependence is weaker for quiescent galaxies. At a fixed mass, Ca II absorption is stronger around star-forming galaxies than quiescent ones especially within impact parameters $<30\,\rm kpc$. Among star-forming galaxies, the Ca II absorption further correlates with SFR, following $\propto \mathrm{SFR^{0.3}}$. However, in contrast to the results at higher redshifts, stronger absorption is not preferentially observed along the minor axis of star-forming galaxies, indicating a possible redshift evolution of CGM dynamics resulting from galactic feedback. Moreover, no significant difference between the properties of the cool gas around AGNs and galaxies is detected. Finally, we measure the absorption profiles with respect to the virial radius of DARK MATTER halos and show that the total Ca II mass in the CGM is comparable to the Ca mass in the ISM of galaxies.
arXiv:2503.22343 [pdf, ps, other]Due to the short gravitational timescale of Sgr A*, variable emissions near the galactic center are expected in the Very-long-baseline interferometry observations. Phenomenologically, the high-flux variable emissions could be interpreted as occasional events from hotspots within accretion disks. It provides a probe of BLACK HOLE (BH) geometry and accretion matter in the strong-field regime of gravity. In this study, we find that light curve profile alone is not proper for distinguishing BH geometries, as our results show that the profiles, even including those from higher-order images, are dependent on hotspot shapes, which are known in practice as amorphous. To alleviate this situation, we examine the spatial-temporal correlations between multiple images of the corotating hotspots. Our results find that the correlations, particularly those from higher-order images, could serve as a robust observable to reflect the inclination angles and BH geometries, because i) the correlated band structure is independent of the hotspot shapes, and ii) the correlations from higher-order images could encode BH geometries and exhibit no overlap with observational signatures from the lower-order ones. We present a comprehensive study on correlations from primary the eighth-order images with various orbital configurations and inclination angles, and show its observational signatures. It is expected that BH geometries can be inferred via the spatial-temporal correlation analysis.
arXiv:2506.23387 [pdf, ps, other]The recent detection of the ultra-high-energy neutrino event KM3-230213A ($\sim$220 PeV) by KM3NeT telescope poses a challenge to conventional astrophysical models, particularly in light of the absence of similar $\gtrsim$100 PeV events in IceCube data, despite its larger exposure. We propose a novel mechanism in which binary BLACK HOLE mergers act as transient neutrino sources via gravitationally induced electroweak vacuum instability. In this scenario, the extreme spacetime curvature near the horizons during the final inspiral phase destabilizes the Higgs vacuum, triggering nucleation of true-vacuum bubbles. Collisions between these bubbles produce microscopic BLACK HOLEs that rapidly evaporate via Hawking radiation, emitting intense, short-lived bursts of neutrinos with energies exceeding 100 PeV. The resulting neutrino fluence follows a heavy-tailed distribution, allowing rare but highly luminous sources to account for events like KM3-230213A while remaining consistent with IceCube's non-detections. This framework links gravitational wave sources to ultra-high-energy neutrino production and suggests that future multi-messenger observations may detect electroMAGNETic signatures from microscopic BLACK HOLE evaporation.
arXiv:2509.25832 [pdf, ps, other]Polarization observations of the Milky Way and many other spiral galaxies have found a close correspondence between the orientation of spiral arms and MAGNETic field lines on scales of hundreds of parsecs. This paper presents POLARIZATION measurements at 214 $μ$m toward ten filamentary candidate ``bones" in the Milky Way using the High-resolution Airborne Wide-band Camera (HAWC+) on the Stratospheric Observatory for Infrared Astronomy (SOFIA). These data were taken as part of the Filaments Extremely Long and Dark: A Magnetic Polarization Survey (FIELDMAPS) and represent the first study to resolve the MAGNETic field in spiral arms at parsec scales. We describe the complex yet well-defined POLARIZATION structure of all ten candidate bones, and we find a mean difference and standard deviation of $-74^{\circ} \pm 32^{\circ}$ between their filament axis and the plane-of-sky MAGNETic field, closer to a field perpendicular to their length rather than parallel. By contrast, the 850 $μ$m POLARIZATION data from \textit{Planck} on scales greater than 10 pc show a nearly parallel mean difference of $3^{\circ} \pm 21^{\circ}$. These findings provide further evidence that MAGNETic fields can change orientation at the scale of dense molecular clouds, even along spiral arms. Finally, we use a power law to fit the dust POLARIZATION fraction as a function of total intensity on a cloud-by-cloud basis and find indices between $-0.6$ and $-0.9$, with a mean and standard deviation of $-0.7 \pm 0.1$. The POLARIZATION, dust temperature, and column density data presented in this work are publicly available online.
arXiv:2509.26108 [pdf, ps, other]We investigate the tidal disruption of a neutron star (NS) near a BLACK HOLE (BH), and for the first time, to the best of our knowledge, near a naked singularity (NaS). For a BH with a mass greater than about $10 M_{\odot}$, the tidal disruption of NS should occur within the event horizon, and hence neither can the stellar material escape nor a distant observer observe the disruption. Since NaS does not have an event horizon, a significant portion of the NS's material can escape, and the tidal disruption can be observed by a distant observer. One could identify such an event from the observed emission from the disrupted NS's material and the decay of the light curve of the disruption event. The escape of a significant fraction of the NS's material may also have implications for the heavy elements in the universe. Moreover, observing such an event can be useful for confirming a NaS, probing its spacetime, and studying the motion of matter in such a geometry. This may help constrain the NS parameters and equation of state models. As a first step in this direction, we calculate here the tidal disruption radius and other parameters for a specific type (Joshi-Malafarina-Narayan type 1) of NaS and compare our results with observations.
arXiv:2510.06352 [pdf, ps, other]The delay time distribution (DTD) of binary BLACK HOLE (BBH) mergers encodes the evolutionary link between the formation history and gravitational-wave (GW) emission. We present a non-parametric reconstruction of the mass-dependent DTD using the BBHs from the GWTC-4 that avoids restrictive assumptions of only power-law forms. Our analysis reveals for the first time the signature for mass-dependent evolutionary pathways: lower-mass systems ($20$-$40\,M_\odot$) are consistent with a scale-invariant DTD, whereas higher-mass BBHs ($40$-$100\,M_\odot$) provide the first direct tentative evidence of DTD that deviate from simple power laws, with a pronounced preference for rapid mergers around $2-6$ Gyrs. These findings reveal the advantage of the non-parametric technique in reconstructing the mass-dependent DTD and discovering for the first-time the presence of a potential time-scale associated with high-mass GW events.
arXiv:2510.07228 [pdf, ps, other]The recently reported binary BLACK HOLE merger, GW231123, has unusual properties that make it hard to explain astrophysically. Parameter estimation studies are consistent with maximally spinning BLACK HOLEs and the dimensionless spin of the more massive component is constrained to be $χ_1\gtrsim 0.8$. Analysis of data also revealed potential systematics that could not be fully replicated with simulated studies. We explore the possibility that these measurements are biased due to unmodeled non-Gaussian noise in the detectors, and that the actual BLACK HOLE spins are more modest. We present evidence for a population of \textit{microglitches} in LIGO gravitational-wave strain data that can lead to biases in the parameter estimation of short-duration signals such as GW231123. Using simulated data of a massive event like GW231123, we demonstrate how microglitches can bias our measurements of BLACK HOLE spins toward $χ\approx1$ with negligible posterior support for the true value of $χ\approx0.7$. We develop a noise model to account for microglitches and show that this model successfully reduces biases in the recovery of signal parameters. We characterize the microglitch population in real interferometer data surrounding GW231123 and find a single detector glitch duty cycle of $0.57_{-0.19}^{+0.21}$, which implies nearly a $100\%$ probability that at least one event through the fourth gravitational wave transient catalog coincides with microglitches in two detectors. We argue that further investigations are required before we can have a confident picture of the astrophysical properties of GW231123.
arXiv:2510.07365 [pdf, ps, other]We present a large spectroscopic survey with \textit{JWST}'s Mid-Infrared Instrument (MIRI) Low Resolution Spectrometer (LRS) targeting $37$ infrared-bright galaxies between $z=0.65-2.46$ with infrared luminosities $\log L_{\rm IR}/L_\odot>11.5$ and $\log M_*/M_\odot=10-11.5$. Targets were taken from a \textit{Spitzer} $24\,μ$m-selected sample with archival spectroscopy from the Infrared Spectrograph (IRS) and include a mix of star-forming galaxies and dust-obscured AGN. By combining IRS with the increased sensitivity of LRS, we expand the range of spectral features observed between $5-30\,μ$m for every galaxy in our sample. In this paper, we outline the sample selection, \textit{JWST} data reduction, 1D spectral extraction, and polycyclic aromatic hydrocarbon (PAH) feature measurements from $λ_{rest}=3.3-11.2\,μ$m. In the \textit{JWST} spectra, we detect PAH emission features at $3.3-5.3\,μ$m, as well as Paschen and Brackett lines. The $3.3\,μ$m feature can be as bright as $1\%$ of the $8-1000\,μ$m infrared luminosity and exhibits a tight correlation with the dust-obscured star-formation rate. We detect absorption features from CO gas, CO$_2$ ice, H$_2$O ice, and aliphatic dust. From the joint \textit{JWST} and \textit{Spitzer} analysis we find that the $11.3/3.3\,μ$m PAH ratios are on-average three times higher than that of local luminous, infrared galaxies. This is interpreted as evidence that the PAH grains are larger at $z\sim1-2$. The size distribution may be affected by coagulation of grains due to high gas densities and low temperatures. These conditions are supported by the observation of strong water ice absorption at $3.05\,μ$m, and can lower stellar radiative feedback as large PAHs transmit less energy per photon into the interstellar medium.
arXiv:2510.07849 [pdf, ps, other]Near-space, which covers altitudes from 20 to 100 kilometers, has been receiving more and more attention because of its special strategic value. Airships and high-altitude balloons are two common types of low-speed vehicles that operate in this region. They can be used for jobs like monitoring, communication, and remote sensing, but they need efficient propulsion systems to work well. Earlier, we proposed a new type of electric propulsion system that can ionize the surrounding air to create plasma and produce thrust for near-space vehicles. However, in past experiments, not enough was known about how certain parameters affect power absorption and electroMAGNETic behavior. Therefore, in this study, we used computer simulations to examine how gas pressure (200 to 1000 Pa), input power (200 to 600 W), frequency (13.56 to 52.24 MHz), and different gas types ($Ar$, $N_2$, $H_2$, $He$) influence inductively coupled plasma inside a quartz tube. We especially focused on comparing two antenna designs: one with a single turn and one with five turns. In all the simulations, the single-turn antenna consistently absorbed power better than the five-turns antenna. Higher frequencies significantly influence both plasma power absorption and MAGNETic field characteristics. The optimal power absorption occurs at a filling gas pressure of 400 Pa. When varying the input power, we observed an initial decrease followed by an increasing trend, which may be related to ionization mechanisms. In comparisons among different gas types, the inelastic collision mechanisms in molecular gases lead to a notable reduction in plasma power absorption efficiency. The results from this work will help guide the design of future experiments for this electric propulsion concept.
arXiv:2510.07954 [pdf, ps, other]Th spontaneous scalarization of the Einstein-Euler-Heisenberg (EEH) BLACK HOLE is performed in the EEH-scalar theory by introducing an exponential scalar coupling (with $α$ coupling constant) to the Maxwell term.Here, the EEH BLACK HOLE as a blad BLACK HOLE is described by mass $M$ and MAGNETic charge $q$ with an action parameter $μ$. A choice of $μ=0.3$ gurantees a single horizon with unrestricted MAGNETic charge $q$. The onset scalarization of this BLACK HOLE appears for a positive coupling $α$ with an unlimited MAGNETic charge $q$. However, there exists a difference between $q\le1$ and $q>1$ onset scalarizations. We notify the presence of infinite branches labeled by the number of $n=0,1,2,\cdots$ of scalarized charged BLACK HOLEs by taking into account the scalar seeds around the EEH BLACK HOLE. We find that the $n=0$ fundamental branch of all scalarized BLACK HOLEs is stable against the radial perturbations, while the $n=1$ excited branch is unstable.
arXiv:2510.08036 [pdf, ps, other]With increased glacial melting and the need to maintain sediment continuity for ecosystem health, sediment-laden flows through hydropower plants are becoming increasingly problematic, particularly due to erosion on runner blades and buckets. A widely used mitigation strategy is the use of filters to protect Pelton turbines. However, these filters lead to rapid sediment accumulation in reservoirs, which must be drained frequently to maintain storage capacity. The high cost of such drainage operations calls for longer intervals between them, without compromising runner integrity, as erosion-induced stress concentrations may cause bucket rupture. A better understanding of the causes of runner erosion under varying operational and sediment conditions is essential to allow more sediment to pass through the hydraulic machine safely. This study investigates how sediment-laden flow through the nozzle affects particle distribution in the JET for different Stokes numbers. Furthermore, it analyses how a realistic particle size and spatial distribution in the impacting JET compares to the assumption of a uniform particle distribution with particles of mean size when simulating bucket erosion in Pelton wheels. The results show that the particle distribution in the JET follows a similar axisymmetric shape for low Stokes numbers whereas at higher Stokes numbers it becomes asymmetric. Additionally, it is shown that imposing uniform particle distribution with particles of mean diameter under-predicts tip- and splitter erosion when simulating the erosion on the bucket but is captured by imposing the realistic size and spatial distribution.
arXiv:2510.08105 [pdf, ps, other]In studies of binary BLACK HOLE (BBH) mergers in eccentric orbits, the mean anomaly, traditionally regarded as less significant than eccentricity, has been thought to encode only the orbital phase, leading to the assumption that it exerts minimal influence on the dynamics of eccentric mergers. In a previous investigation, we identified consistent oscillations in dynamical quantities peak luminosity $L_{\text{peak}}$, remnant mass $M_{\text{rem}}$, spin $α_{\text{rem}}$, and recoil velocity $V_{\text{rem}}$ in relation to the initial eccentricity $e_0$. These oscillations are associated with integer orbital cycles within a phenomenological framework. In this paper, we aim to explore the underlying physical nature of these oscillations through gravitational waveforms. Our examination of remnant mass and spin reveals that while the initial ADM mass $M_{\mathrm{ADM}}$ and orbital angular momentum $L_0$ exhibit gradual variations with $e_0$, the radiated energy $E_{\text{rad}}$ and angular momentum $L_{\text{rad}}$ display oscillatory patterns akin to those observed in $M_{\text{rem}}$ and $α_{\text{rem}}$. By decomposing the waveforms into three distinct phases inspiral, late inspiral to merger, and ringdown, we demonstrate that these oscillations persist across all phases, suggesting a common origin. Through a comparative analysis of $E_{\text{rad}}$ and $L_{\text{rad}}$ derived from numerical relativity (NR), post-Newtonian (PN) waveforms, and orbital-averaged PN fluxes during the inspiral phase, we identify the initial mean anomaly $l_0$ as the source of the observed oscillations. ...
arXiv:2510.08135 [pdf, ps, other]Weak-line QUASARs (WLQs) are a subset of type 1 QUASARs with remarkably weak high-ionization broad emission lines but normal optical/UV continua. Using 371,091 QUASARs from SDSS DR16, we define WLQs by analyzing outliers in three relations: the L1350-CIV blueshift, the Baldwin effect, and the logL2500-alpha_ox. We find two CIV EW thresholds: $8.9\pm0.2$Å and $19.3\pm0.3$Å. WLQs (EW(CIV)<$8.9\pm0.2$Å) have enhanced CIV blueshifts, deviate from the Baldwin effect, and include many X-ray weak objects (nearly half). Normal QUASARs (EW(CIV)>$19.3\pm0.3$Å) show typical properties, while bridge QUASARs (intermediate EW) are transitional. WLQs show a positive correlation between line attenuation and ionization energy: high-ionization lines (e.g., HeII, CIV) are suppressed by ~3-4σ compared to low-ionization lines (e.g., MgII, OI). This supports the shielding gas model, where a thick inner accretion disk obscures high-energy photons, suppressing high-ionization lines, while low-ionization lines are less affected. We suggest that WLQs and normal QUASARs correspond to slim and thin disk regimes, respectively, with bridge QUASARs as a transitional phase. This work provides a unified criterion for WLQs and highlights the role of accretion-driven shielding gas in their spectral features.
arXiv:2510.08367 [pdf, ps, other]Title: A broadband study of FRB20240114A with the Effelsberg 100-m radio telescopeAuthors: P. Limaye, L. G. Spitler, N. Manaswini, J. Benáček, F. Eppel, M. Kadler, L. Nicotera, J. Wongphechauxsorn,Comments: 15 pages, 7 figures, submitted to A&ASubjects: astro-ph.HECreated: 2025-10-09; Updated: 2025-10-10; Datestamp: 2025-10-10We present Effelsberg 100-m telescope observations of the hyperactive repeating fast radio burst source FRB 20240110A, discovered by CHIME/FRB in January 2024. Using the Ultra BroadBand (UBB) receiver, spanning 1.3-6.0 GHz, we detected over 700 unique bursts across four observing epochs. A comprehensive analysis of their temporal and spectral properties reveals four distinct spectro-temporal morphologies, including simple, complex and frequency-drifting structures. No bursts were detected across the full UBB band, confirming the band-limited emission typical of repeating FRBs. We find modest frequency evolution in burst widths but constant fractional bandwidths, and strong variability in burst rates that may be influenced by scintillation. The waiting-time distributions indicate predominantly independent burst events, with occasional clustering suggesting a characteristic emission timescale of $\sim$10 ms. Additionally, this study presents a multi-frequency analysis of waiting-time distributions, offering new insights into the complex frequency drifts commonly observed in repeating FRBs. These broadband observations provide a detailed view of the frequency-dependent burst behavior of FRB 20240110A and offer insights into the variability and temporal structure of repeating FRB emission.
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