Current date: 2026-09-24
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Datestamp limit: 2026-09-24 (0 days ago)
Created/updated limit: 2026-09-17 (7 days ago)
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Suggested sets: physics, physics:astro-ph, physics:gr-qc, physics:physics
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Scoring abstracts
Number of records retrieved: 839
Keyword score statistics
score 10 -- 1 abstracts
score 8 -- 1 abstracts
score 7 -- 1 abstracts
score 6 -- 4 abstracts
score 5 -- 7 abstracts
score 4 -- 5 abstracts
score 3 -- 12 abstracts
score 2 -- 28 abstracts
in total -- 59 abstracts
Articles that appeared on 2026-09-24
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[abstract 1 / 59] Wow! (score: 10)
- Title: Disk truncation triggers RELATIVISTIC JET launching of a highly accreting supermassive BLACK HOLEAuthors: Hirofumi Noda, Kazuhiro Hada, Hiroto Maruyama, Taishu Kayanoki, Kenji Toma, Taiki Kawamuro, Yoshiyuki Inoue, Tomohisa Kawashima, Soyeon Yeo, Ilje Cho, Keiichi Asada, Yasushi Fukazawa, Yoshihiro Ueda,Comments: 14 pages, 6 figures, 2 tables, Accepted for publication in the Astrophysical Journal LettersSubjects: astro-ph.HE astro-ph.GACreated: 2026-09-22; Updated: 2026-09-24; Datestamp: 2026-09-24
Relativistic JETs are among the most energetic phenomena in the Universe and influence galaxy evolution through energetic feedback, yet the physical connection between accretion flows and JET launching remains unresolved. Jet production is widely attributed to the Blandford-Znajek mechanism, which extracts BLACK HOLE rotational energy via large-scale MAGNETic fields sustained by an accretion flow. Although this mechanism is observationally well supported for hot, geometrically-thick accretion flows, highly accreting environments with strong JETs present a paradox, as they are typically dominated by cold, geometrically-thin disks incapable of sustaining large-scale MAGNETic fields. Here, we report coordinated X-ray microcalorimeter spectroscopy achieved by X-ray Imaging and Spectroscopy Mission (XRISM) and millimeter/radio interferometric observations by Global Millimeter VLBI Array (GMVA), Very Long Baseline Array (VLBA), and East Asian VLBI Network (EAVN) on the broad-line RADIO GALAXy 3C120. High-resolution X-ray spectroscopy reveals a RELATIVISTICally-broadened Fe-K$α$ line, indicating that the cold, geometrically-thin disk is truncated at $\sim 20~R_{\rm g}$ ($R_{\rm g}$ is the gravitational radius), with the inner region replaced by a hot, geometrically-thick flow. Concurrently, radio imaging indicates that JET profile extrapolation toward the BLACK HOLE horizon yields a radius comparable to or even narrower than the disk truncation radius. These results demonstrate that, even at high accretion rates, JET launching is linked to a hot inner flow, possibly via the Blandford-Znajek process, providing evidence for a universal disk-JET connection via geometric transition.
[abstract 2 / 59] Wow! (score: 8) - Title: Anisotropy and energy distribution of leptons and photons in radiative RELATIVISTIC Alfvénic turbulenceAuthors: Peng Liu, Xiaochun Wei, Zheng Gong,Comments: Published in PRDSubjects: physics.plasm-ph astro-ph.HECreated: 2026-09-23; Updated: 2026-09-24; Datestamp: 2026-09-24
The anisotropic evolution of RELATIVISTIC particles in MAGNETically dominated Alfvénic turbulence is a fundamental process governing nonthermal emissions in high-energy astrophysical environments. In this work, we develop a theoretical framework by deriving scaling equations that characterize the pitch-angle dynamics of leptons and photons across both weak- and strong-radiative cooling regimes. Our model reveals a universal coupling between particle energy and angular distribution, arising from the interplay of field-aligned accelerations, perpendicular drift motions, and radiation reactions. The model can uniquely identify ``turning-point energies" that exhibit a nonlinear dependence on the local MAGNETic field and the energy-injection scale. The validity of this scaling model is confirmed through radiative particle-in-cell simulations. We show that the electron pitch-angle distribution fundamentally dictates photon emission characteristics, further revealing a pronounced statistical correlation between high-energy photon emission and turbulent vortices in the RECONNECTion regions. By bridging the gap between small-scale kinetic interactions and broad-band spectral characteristics, this work provides a quantitative basis for interpreting the hardening of radiation spectra and complex POLARIZATION signatures in sources such as pulsar wind nebulae and GAMMA-RAY BURSTs.
[abstract 3 / 59] Wow! (score: 7) - Title: Study of BLAZAR variability through their flux distribution for CTAO long-term monitoringAuthors: A. Mikhno, J. Biteau, J. -P. Lenain on behalf of the CTAO collaboration,Comments: contribution to the 2026 Very High Energy Phenomena in the Universe session of the 60th Rencontres de MoriondSubjects: astro-ph.HECreated: 2026-09-23; Updated: 2026-09-24; Datestamp: 2026-09-24
The CTAO Key Science Project on Active Galactic Nuclei (AGN) includes a long-term monitoring (LTM) program of BLAZARs. The probability distribution function (PDF) of the flux extracted from unbiased BLAZAR lightcurves can provide important insight into the physical processes taking place in RELATIVISTIC JETs and their connection to observed variability. The aim of this work is to define an optimal observational strategy for the CTAO LTM program using the flux distributions as a quantitative metric. To achieve this goal, we develop a simulation-based analysis framework that enables a systematic comparison of different observational strategies. Light curves were simulated as would be observed with the future CTAO for a representative set of AGN sources, following four different observational strategies within a fixed time budget. For each simulated light curve, different PDF models were fitted and their goodness of fit was evaluated. Based on the best-fit parameters, Monte Carlo simulations were generated to assess the ability of the method to recover the underlying PDF model. Since the true model used to generate the simulated light curves is known, this procedure allows us to quantify the discriminatory power of the algorithm and to identify which observational strategy maximizes model discrimination. Additionally, the algorithm has the potential of discrimination against different models for the flux distributions, such as Gaussian and lognormal. Once validated on simulations, the method is applied to archival lightcurves from existing gamma-ray instruments to extract flux PDFs and study the physical processes driving BLAZAR variability. The analysis framework has been developed and tested on simulated CTAO-like data, showing good stability and robustness. A study to optimize the observing strategy for the CTAO LTM is presented.
[abstract 4 / 59] Yes (score: 6) - Title: EP260119a: A High-Redshift Gamma-Ray Quiet Fast X-ray Transient Probing a Potentially Hidden Population of Relativistic ExplosionsAuthors: Camila Angulo-Valdez, Asuka Kuwata, Edilberto Aguilar-Ruiz, Rosa L. Becerra, Ramandeep Gill, Miguel Angel Aloy, Antonio de Ugarte Postigo, Alan M. Watson, Chen-Wei Wang, Diego López-Cámara, Daniel A. Perley, Aleksandra Bochenek, Simone Dichiara, Enrique Moreno Méndez, Nathaniel R. Butler, Benjamin Schneider, Jean-Luc Atteia, Stéphane Basa, William H. Lee, Dalya Akl, Sarah Antier, Alexis Coleiro, James DeLaunay, Damien Dornic, Jean-Grégoire Ducoin, Francis Fortin, Dmitry Frederiks, Leonardo García-García, Noémie Globus, Olivier Godet, Jamie Kennea, Gianluca Lombardi, Alexandra L. Lysenko, Francesco Magnani, Tyler Parsotan, Margarita Pereyra, Anna Ridnaia, Samuele Ronchini, Fredd Sánchez-Álvarez, Dmitry Svinkin, Anastasia Tsvetkova, Mikhail Ulanov, Peter Veres, Hui Yang,Comments: 19 pages, 12 figures. Submitted to MNRAS. Comments are welcomeSubjects: astro-ph.HECreated: 2026-09-22; Updated: 2026-09-24; Datestamp: 2026-09-24
Gamma-ray quiet fast X-ray transients (FXTs) provide a new approach for studying RELATIVISTIC explosions that evade traditional gamma-ray triggers. In this work, we present multi-wavelength observations and analysis of EP260119a, a high-$z$ FXT detected by Einstein Probe/WXT and followed up with COLIBRÍ, the Liverpool Telescope, and other facilities. Spectroscopy yields a redshift of $z = 5.47$, making EP260119a the most distant FXT detected by Einstein Probe to date. Despite its luminous X-ray and optical emission, no prompt gamma-ray counterpart was detected by SVOM/ECLAIRs, SVOM/GRM, SWIFT/BAT, or Konus/Wind, despite contemporaneous coverage. The broadband afterglow is well described by SYNCHROTRON emission from a uniform RELATIVISTIC JET propagating into a shallowly stratified external medium close to the constant-density limit, indicating a standard RELATIVISTIC explosion despite the absence of detectable gamma rays. Occupying the extreme high-$z$ end of the growing Einstein Probe FXT sample, EP260119a supports the possibility that soft X-ray surveys are uncovering RELATIVISTIC transients that remain undetected by current gamma-ray instruments. Our results indicate that some explosions in the early Universe escape conventional gamma-ray surveys and demonstrate the value of combining sensitive soft X-ray discovery with rapid optical follow-up to obtain a more complete view of the high-$z$ transient population.
[abstract 5 / 59] Yes (score: 6) - Title: Is accretion flow MAGNETically arrested in M87?Authors: Yuao Ma, Xinwu Cao, Jia-Wen Li, Jianchao Feng, Qingwen Wu,Comments:Subjects: astro-ph.HECreated: 2026-09-23; Updated: 2026-09-24; Datestamp: 2026-09-24
It is still debating on whether the disc is MAGNETically arrested in M87. We assume that a weak external MAGNETic field is dragged inwards by the accretion disc, which is substantially enhanced to drive strong JETs near the BLACK HOLE horizon via Blandford-Znajek mechanism. The JET power of M87 has been well constrained with the observational data, while the accretion rate in the inner region of the accretion flow in M87 is estimated by fitting the multi-waveband continuum spectrum and the data of the Faraday rotation measurement, with which the surface density of the disc is derived. Our calculations show that, in order to produce the observed JET power $P_{\rm JET}=3.2\times 10^{43}~\rm erg~s^{-1}$, an external field with several hundred $μ\rm G$ at the outer edge of the disc is required to be amplified in the disc to hundreds G at the BH horizon, and the accretion flow in M87 must be MAGNETically arrested. A standard and normal evolution (SANE) disc is allowed in M87, only if the JET power is significantly lower than $\sim 1.75 \times 10^{43} \rm erg~ s^{-1}$,
[abstract 6 / 59] Yes (score: 6) - Title: Multi-Band Optical Variability Characteristics of the $γ$-ray emitting BLAZAR 1ES 0647+250 during its 2020 flareAuthors: K. Subbu Ulaganatha Pandian, C. S. Stalin, S. Muneer, S. Umayal, Aditi Agarwal, Amit Kumar Mandal, B. Natarajan,Comments: Accepted for publication in Journal of Astrophysics and AstronomySubjects: astro-ph.HE astro-ph.GACreated: 2026-09-23; Updated: 2026-09-24; Datestamp: 2026-09-24
We present a multi-band optical variability study of the $γ$-ray emitting high-SYNCHROTRON-peaked BLAZAR 1ES~0647+250 during its enhanced optical activity in 2020. The analysis utilizes 107 epochs of high-precision $B$, $V$, and $R$-band photometry obtained with the 75 cm telescope at the Vainu Bappu Observatory, combined with high-cadence $z_g$ and $z_r$ survey data from the Zwicky Transient Facility. The combined light curves reveal coherent variability across all optical filters, with the source reaching a peak $R$-band magnitude of 15.74 mag. We calculated the variability amplitude, finding the highest intrinsic variability in the B- band. Spectral analysis using color--magnitude diagrams reveals a statistically significant ``Bluer-When-Brighter'' trend, supported by a Pearson correlation coefficient of $r = 0.68$ ($p < 0.001$) for the (V$-$R) index. Furthermore, the discrete correlation function analysis indicates a near-zero time lag between the $V$ and $R$ bands, suggesting simultaneous emission within the observational cadence. The observed spectral hardening is consistent with SYNCHROTRON-dominated optical emission, likely associated with enhanced particle acceleration within the JET during the active phase of 1ES~0647+250.
[abstract 7 / 59] Yes (score: 6) - Title: A Tentative Line-like GeV Excess in FERMI Blazar 4FGL J1754.2+3212: Implications for Jet Physics and BeyondAuthors: Shi-Ju Kang, Yue Yin, Yong-Gang Zheng, Qingwen Wu,Comments: 8 pages, 3 figures, 1 table, Comments are welcome!Subjects: astro-ph.HECreated: 2026-09-23; Updated: 2026-09-24; Datestamp: 2026-09-24
We report the detection of a tentative, narrow spectral feature in the GeV gamma-ray spectrum of the BLAZAR 4FGL J1754.2$+$3212, using approximately 16.5 years of observations from the FERMI Large Area Telescope. A detailed likelihood analysis of the time-averaged spectrum reveals a localized, line-like excess at an energy of $\sim$31 GeV, with a local statistical significance of $\sim$3$σ$ (3 degrees of freedom), without corrections for multiple trials and the look-elsewhere effect. This feature is not well described by standard smooth continuum models such as a single log-parabola. The addition of a Gaussian component significantly improves the spectral fit. If confirmed by future observations with higher sensitivity, this feature would represent a novel phenomenon in BLAZAR astrophysics. We explore its potential physical origins, which could involve exotic processes such as DARK MATTER annihilation or photon-axion-like-particle oscillations, or extreme astrophysical mechanisms within a structured JET. Regardless of its ultimate nature, this finding highlights the potential of deep spectral studies of BLAZARs to reveal non-standard physics and challenges conventional one-zone emission models. Definitive verification awaits observations by next-generation instruments, particularly the Very Large Area $γ$-ray Space Telescope (VLAST).
[abstract 8 / 59] Yes (score: 5) - Title: $E_{\rm peak}$-$α$ Correlation in Time Resolved GRB Spectra: A Bottom-Up Approach with Optically Thin Inverse Compton Scattering ModelAuthors: Pragyan Pratim Bordoloi, Ayush Shivkumar, Shabnam Iyyani,Comments: This manuscript has already been submitted to the Astrophysical Journal. No review has come yetSubjects: astro-ph.HECreated: 2026-09-23; Updated: 2026-09-24; Datestamp: 2026-09-24
Gamma-ray bursts (GRBs) are the brightest explosions in the Universe, yet the origin of their emission remains uncertain. Time-resolved spectral analysis offers key insights into the evolution of spectral shapes, constraining both radiation mechanisms and emission-site microphysics. Observationally, GRB spectra are well described by the empirical Band function, characterized by the peak energy ($E_{\mathrm{peak}}$) and low-energy spectral index ($α$). We investigate the temporal evolution of spectra produced by optically thin inverse-Compton scattering (ICS) within a standard fireball JET framework, focusing on the scenarios that can produce the two commonly observed spectral evolution patterns: hard-to-soft evolution and intensity tracking, within a single emission pulse. The evolution is analysed using both Bayesian block and constant-fluence binning, with the observed spectrum modeled consistently using the Band function. Using this bottom-up approach, we find that optically thin ICS yields a positive $E_{\mathrm{peak}}$-$α$ correlation, with $α$ evolving from hard (Planck-like, $> +0.5$) to softer ($< -0.67$) values. Such hard $α$ values are inconsistent with standard SYNCHROTRON emission. This characteristic evolution in the $E_{\mathrm{peak}}$-$α$ plane, therefore, provides a diagnostic signature of optically thin ICS as the dominant radiation mechanism during the prompt phase of GRBs. Furthermore, this type of smooth evolution of $α$ within a single pulse does not require invoking a transition between different radiation mechanisms, unless additional observational evidence supports such a change.
[abstract 9 / 59] Yes (score: 5) - Title: A Coherent Search for New Galactic Magnetars using FERMI/GBM and follow-up SWIFT/BAT: 7 Candidates and a Large Burst CatalogAuthors: Ariel Perera, Barak Zackay, Tejaswi Venumadhav,Comments:Subjects: astro-ph.HECreated: 2026-09-22; Updated: 2026-09-24; Datestamp: 2026-09-24
Galactic MAGNETars are a rare class of neutron stars with extreme MAGNETic fields, with only about 30 known sources. Their short hard X-ray and soft GAMMA-RAY BURSTs provide an important channel for discovering MAGNETar activity. Wide-field instruments such as the FERMI Gamma-ray Burst Monitor (GBM) are well suited to detecting these bursts, but their broad localization uncertainties make it difficult to associate individual bursts with specific sources. Coded-aperture telescopes, in contrast, provide arcminute-scale localizations but have narrower fields of view. We search for previously unidentified MAGNETars and construct a MAGNETar burst catalog by combining a broad sample of short, soft triggers from our coherent GBM detection pipeline over 2013-2025 with targeted searches of archival SWIFT/BAT images. We develop a statistical association framework that uses BAT detections to localize GBM bursts to arcminute precision, together with a spatio-temporal clustering framework that associates poorly localized bursts with common sources. Together, these methods identify 1720 MAGNETar bursts, of which 1170 are confidently associated with 11 known MAGNETars. The remaining 550 bursts could not be assigned to specific sources. We identify seven candidate new MAGNETars through three complementary discovery channels. The catalog, composed of the associated bursts, extends to the lowest fluences observed by GBM. We also provide spectral and temporal analyses of the catalog. The new candidate sources provide targets for X-ray follow-up that could reveal previously unidentified Galactic MAGNETars. More broadly, this work demonstrates how combining instruments with complementary capabilities can maximize the scientific return of high-energy transient observations.
[abstract 10 / 59] Yes (score: 5) - Title: Waiting in the wings: extended emission GRBs from high latitude emission and JET expansionAuthors: Isabelle Worssam, Benjamin P. Gompertz, Hendrik J. van Eerten,Comments: Submitted to MNRASSubjects: astro-ph.HE astro-ph.COCreated: 2026-09-22; Updated: 2026-09-24; Datestamp: 2026-09-24
The process powering extended emission (EE) Gamma Ray-Bursts (GRBs) from compact object mergers is a debated problem due to their observed prompt emission timescales of 10 to 100s, far in excess of the expected accretion timescales following a binary neutron star (BNS) merger. Here, we present an analytical thin shell structured JET model designed to alleviate this tension. We show that a changing JET structure in which early emission is produced by a high Lorentz factor narrow, structured JET and later emission comes from a wider, lower Lorentz factor tophat-like JET can successfully reproduce the EE GRB phenomenology. All emitting shells are powered by a $0.1$ $M_{\odot}$ accretion torus and launched within a time window of 2s after merger. Spatially-resolved opacity checks confirm that our emission sites remain optically thin, in part due to the spectral softness associated with EE. We present light curves from our model compared to representative EE bursts detected by SWIFT: GRBs 211211A, 211227A and 060614. While our light curves provide good matches to the data, our spectra do not evolve fast enough when compared to the well-measured spectral evolution observed in GRB 211211A. We discuss an update to the model incorporating inherent spectral evolution in the shells as future work. We also show a parameter exploration of the model and identify a parameter range within which standard short GRB-like light curves could be produced, showcasing the ability of the model to produce short bursts with and without EE.
[abstract 11 / 59] Yes (score: 5) - Title: In-Situ Star Formation in a Thick Disk: A Model for Metal Enrichment of Mrk 573Authors: Hannalore J. Gerling-Dunsmore, Mitchell C. Begelman, Jared A. Goldberg, Taeho Ryu, Dominika Ł. Król,Comments: 13 pages, 1 table, 1 figure; submitted to ApJ, under reviewSubjects: astro-ph.HE astro-ph.GACreated: 2026-09-22; Updated: 2026-09-24; Datestamp: 2026-09-24
Recent observations of the nearby Seyfert galaxy Mrk 573 found that the galactic nucleus and bicone regions surrounding the JET are significantly metal-enriched. In this paper, we develop a simple model for the observed metal enrichment, assuming a population of stars in the $10 - 30 \, M_{\odot}$ range formed in-situ in the accretion disk. We assume the stars form according to a Salpeter initial mass function and generate the typical metal yields expected of field stars of the same mass. We find that in the thick disk ($H/r \sim 0.1$) case, a Salpeter population of stars can easily explain the observed metal enrichment and provide limits on the formation model; we also argue that a thin disk ($H/r \lesssim 0.01$) is incompatible with the observed metal enrichment. In our model, AGN metallicity scales most strongly with disk thickness, implying a potentially powerful observable diagnostic.
[abstract 12 / 59] Yes (score: 5) - Title: Estimating redshift distributions of FERMI BLAZARs with multiple machine-learning modelsAuthors: Kerui Zhu, Jiaming Chen, Yonggang Zheng, Ruixin Zhou, Shan Chang, Li Zhang, Niansheng Tang,Comments: 13 pages, 7 figures. Accepted for publication in Astronomy & AstrophysicsSubjects: astro-ph.HE astro-ph.IMCreated: 2026-09-23; Updated: 2026-09-24; Datestamp: 2026-09-24
Approximately half of the FERMI-LAT-detected BLAZARs lack spectroscopic redshift measurements, which limits population studies and investigations of the cosmological evolution of the gamma-ray BLAZAR population. We aim to develop a multi-model ensemble framework to systematically evaluate the performance of machine-learning models for BLAZAR redshift estimation and to provide predictive redshift probability distributions with quantified uncertainties for all BLAZARs without measured redshifts. We construct an ensemble of 35 machine-learning regression models in the $1/(1+z)$ space. Predictions from individual models are combined to build non-parametric redshift probability density functions (PDFs) for each source, allowing an explicit characterization of predictive uncertainty. The source-level PDFs are subsequently stacked to derive population-level redshift distributions. Across the diverse models within our framework, we find comparable predictive performance, indicating a feature-limited performance plateau. We compile a catalog of predictive redshift distributions for 1,590 BLAZARs without measured redshifts. The stacked PDFs recover the characteristic double-peaked redshift structure of BLAZARs without using source class labels. For BLAZAR candidates of uncertain type, the predicted redshift distribution exhibits a bimodal structure, suggesting a slightly larger contribution from FSRQ-like sources. Our multi-model statistical framework achieves competitive predictive performance while retaining faint sources. We provide predicted redshift distributions with quantified uncertainties for 1,590 BLAZARs without measured redshifts, offering improved support for population and evolutionary studies. More broadly, this approach highlights the practical value of uncertainty-aware multi-model regression ensembling in astronomical data analysis.
[abstract 13 / 59] Yes (score: 5) - Title: A MAGNETar-powered JET-wind outflow in GAMMA-RAY BURST-associated SUPERNOVAe: Application to the thermal components of GRB 060218-SN 2006ajAuthors: Yun-Peng Li, Da-Bin Lin,Comments: Accepted by A&ASubjects: astro-ph.HECreated: 2026-09-23; Updated: 2026-09-24; Datestamp: 2026-09-24
A rapidly rotating MAGNETar formed in the collapse of a massive star may release its spin-down power through both a collimated polar JET and a quasi-isotropic MAGNETar wind. With its long-lasting soft X-ray blackbody component and the double-peaked UV/optical light curves of SN 2006aj, GRB 060218-SN 2006aj provides a useful test case for such a two-component energy-injection scenario. We developed a MAGNETar-powered JET-wind model in which the two outflows interact with homologously expanding SN ejecta, driving forward shocks that produce shock-breakout emission and subsequent MAGNETar-powered thermal emission. We first used the JET component to fit the 0.3-10 keV blackbody flux and temperature evolution of GRB 060218 and subsequently added the wind component to model the UV/optical light curves of SN 2006aj. We find that the soft X-ray blackbody component can be reproduced mainly by shock-breakout emission from the polar ejecta driven by the JET. The double-peaked UV/optical light curves are instead produced by the interaction between the quasi-isotropic MAGNETar wind and a more massive ejecta component. The first optical peak is dominated by wind-driven shock-breakout emission, whereas the broader and later emission is powered mainly by the subsequent MAGNETar-powered thermal component. Our results suggest a two-component MAGNETar-engine picture for GRB 060218-SN 2006aj, in which the X-ray thermal emission and the UV/optical double-peaked evolution arise from different energy-injection channels of the same central engine.
[abstract 14 / 59] Yes (score: 5) - Title: Linear Growth Rate of Compressible Tearing Instability in a Force-Free Current SheetAuthors: Chen Shi, Marco Velli,Comments:Subjects: physics.plasm-phCreated: 2026-09-23; Updated: 2026-09-24; Datestamp: 2026-09-24
We investigate the linear growth rate of tearing instability in a resistive force-free current sheet using the linearized fully-compressible MAGNETohydrodynamics (MHD) equations. Our results show that, as the plasma beta ($β$), which is proportional to the ratio of thermal pressure to MAGNETic pressure, increases, the dispersion relation approaches that of the incompressible tearing mode. As $β$ decreases, the growth rate increases but this increase remains finite even in the limit $β\rightarrow 0$. The relative increase in the growth rate from $β= +\infty$ to $β=0$ depends on the Lundquist number, with lower Lundquist numbers showing a more pronounced increase. These findings indicate that, while compressibility has a negligible effect on the growth rate of tearing instability in high Lundquist number regimes, its effect becomes significant at low Lundquist numbers. This suggests that compressibility may influence the critical Lundquist number for the transition from laminar to plasmoid-dominated MAGNETic RECONNECTion. Moreover, in low-$β$ regimes ($β< 1$), the generated density perturbation can be substantial, comparable to or even larger than the MAGNETic field perturbation, even though the growth rate is only slightly modified by the compressibility.
[abstract 15 / 59] Yes (score: 4) - Title: EP250302a: violent shell collision in a soft-X-ray-selected GRB-like transientAuthors: Shao-Yu Fu, Cui-Yuan Dai, Ai-Ling Wang, Wei-Hua Lei, Dong Xu, Tao An, Jin-Jun Geng, Xiang-Yu Wang, Shuai-Qing Jiang, Zi-Pei Zhu, Xing Liu, Jie An, Lin-Bo He, Jun-Jie Jin, Yu Zhang, Jinlei Zhang, Zhou Fan, Xing Gao, Abdusamatjan Iskandar, Shahidin Yaqup, Tu-Hong Zhong, Ali Esamdin, Chun-Hai Bai, Yu Zhang, He Gao, Xue-Feng Wu, Daniele Bjørn Malesani, Luca Izzo, R. A. J. Eyles-Ferris, A. Saccardi, B. Schneider, J. Palmerio, N. R. Tanvir, Alexei Pozanenko, Nicolai Pankov, A. S. Moskvitin, O. I. Spiridonova, O. A. Maslennikova, A. Volnova, E. Klunko, V. Rumyantsev, A. Volvach, L. Volvach, Toktarkhan Komesh, Ernazar Abdikamalov, Dilda Berdikhan, Zhanat Maksut, Yuan-Chuan Zou, Hong-Zhou Wu, Yun-Wei Yu, Rong-Feng Shen, Yi-Han Wang, Hui Sun, Bin-Bin Zhang, Liang-Duan Liu, Ye Li, Valerio D'Elia, Ruben Salvaterra, Massimiliano De Pasquale, Bing Zhang, Wei-Min Yuan,Comments: Accepted by ApJLSubjects: astro-ph.HECreated: 2026-09-23; Updated: 2026-09-24; Datestamp: 2026-09-24
The Einstein Probe opens a previously unexplored soft X-ray window onto GAMMA-RAY BURSTs, filling a critical observational gap in the soft X-ray coverage of their prompt emission. In this letter, we present EP250302a, a soft-X-ray-selected, GRB-like transient at $z=1.131$ detected by the Einstein Probe. Follow-up observations from X-ray to radio reveal a narrow X-ray flare at $\sim 1.1$\, ks and subsequent achromatic optical and X-ray rebrightening. These features challenge a standard single-component afterglow model and indicate the need for multiple ejecta components. A violent collision between a late RELATIVISTIC shell and the decelerated leading blast wave provides a plausible interpretation: the flare arises from internal dissipation of the late ejecta, while the rebrightening is powered by the shocked emission produced in the collision. Quantitative modeling constrains the kinetic energy ratio between the late shell and the initial ejecta to $E_{\rm k,iso,2}/E_{\rm k,iso,1} \sim 5$ (with $E_{\rm k,iso,2} \sim 10^{53}$~erg and $E_{\rm k,iso,1} \sim 2\times10^{52}$~erg), as well as the Lorentz factor contrast to $Γ_{2,0}/Γ_{1,0} \approx 0.98$--$2.27$, required to reproduce the observed flare luminosity and rebrightening amplitude. Such an energetic late shell can be launched in a radiatively inefficient second episode of central-engine activity. Thanks to the well-sampled, early-time multiband coverage facilitated by the EP trigger, EP250302a provides a valuable case to test the physical connection between central-engine activity and shell collisions.
[abstract 16 / 59] Yes (score: 4) - Title: Orbital and spin periods of the intermediate polar 2PBC J0800.5-4306Authors: Yabing Zhao, Chunhua Zhu, Sufen Guo, Guoliang Lü, Xizhen Lu, Xinyu Liu,Comments:Subjects: astro-ph.SR astro-ph.HECreated: 2026-09-23; Updated: 2026-09-24; Datestamp: 2026-09-24
2PBC J0800.5$-$4306 (SWIFT J0800.7$-$4309; optical counterpart Gaia DR3 5533020382479508736) is a hard-X-ray-selected cataclysmic variable whose MAGNETic subtype had remained uncertain. We analyse \textit{TESS} photometry from Sectors 88 and 89 and archival \textit{XMM-Newton} timing data. The \textit{TESS} data show signals at the orbital frequency $Ω$, its first harmonic $2Ω$, the white-dwarf spin frequency $ω$, and the spin--orbit beat frequency $ω-Ω$. We measure $P_{\rm orb}=5.38540^{+0.00027}_{-0.00028}$ h and $P_{\rm spin}=0.7015570^{+0.0000059}_{-0.0000062}$ h. The \textit{XMM-Newton} EPIC-pn, MOS1, and MOS2 periodograms show broad peaks near the 2525.6-s (0.701557-h) optical spin period. Together with the previously published cataclysmic variable classification and SWIFT/BAT hard-X-ray detection, these timing results identify 2PBC J0800.5$-$4306 as an intermediate polar. We report the first published measurements of its orbital and white-dwarf spin periods, while SPOC difference-image diagnostics and pixel-level timing tests support that the measured \textit{TESS} modulations are associated with the Gaia counterpart despite the crowded field.
[abstract 17 / 59] Yes (score: 4) - Title: PANGU I: A Parthenon-Based Framework for Fixed-Spacetime GRMHDAuthors: Yuehang Li, Fan Zhou, Mingyang Luan, Minyong Guo, Bin Chen,Comments: 21 pages, 10 figures, 4 tablesSubjects: astro-ph.HE gr-qcCreated: 2026-09-23; Updated: 2026-09-24; Datestamp: 2026-09-24
Existing general-RELATIVISTIC MAGNETohydrodynamics (GRMHD) codes offer complementary capabilities, but these capabilities remain distributed across different frameworks. To unify them, we introduce PANGU--Parthenon-Based Astrophysics for Numerical Relativity and GRMHD in a Unified Framework--a modular computational framework that integrates a shared solver across physical regimes, flexible spacetime geometry, and extensible computational infrastructure within a single architecture. In the first paper of this series, we present and validate the fixed-spacetime GRMHD component of PANGU. The shared solver combines finite-volume Godunov methods with constrained transport on uniform and block-structured, statically refined meshes, and covers hydrodynamics and MAGNETohydrodynamics in Newtonian, special-RELATIVISTIC, and general-RELATIVISTIC regimes. PANGU provides a flexible geometry interface supporting coordinate selection and either on-the-fly or precomputed evaluation of prescribed stationary spacetimes, demonstrated here in Kerr spacetime with Cartesian Kerr-Schild and modified Kerr-Schild coordinates; additional components can be incorporated without restructuring the core solver. Verification covers all three regimes on uniform and statically refined meshes: smooth Newtonian and special-RELATIVISTIC problems approach second order against their analytic solutions, with deliberately matched double-precision trajectories agreeing with AthenaK to roundoff; in fixed-spacetime GRMHD, the stationary analytic solutions are preserved to second order, and the turbulent accretion reproduces the same flow and flux scales as BHAC. Together, these results establish the fixed-spacetime matter-sector foundation for the broader PANGU framework. Numerical-relativity and coupled dynamical-spacetime GRMHD capabilities will be presented in subsequent work.
[abstract 18 / 59] Yes (score: 4) - Title: White Dwarf Pulsars: an emerging class of compact binariesAuthors: David A. H. Buckley,Comments: 15 pages, 11 figures. Accepted conference proceedings paper for The Golden Age of Cataclysmic Variables and Related Objects - VII, Palermo, Italy, 1-6 September 2025Subjects: astro-ph.SR astro-ph.HECreated: 2026-09-23; Updated: 2026-09-24; Datestamp: 2026-09-24
I summarise the expanding class of white dwarf pulsars for which the prototype, AR Scorpii, was only discovered in 2016. At the time of this meeting, two further systems had been found (eRASSU J191213.9-441044 and SDSS J230641.47+244055.8). These are thought to be detached (or nearly detached) white-dwarf--red-dwarf binaries, where the white dwarf's MAGNETic field interacts with the M-star's corona, resulting in the capture and acceleration of electrons to RELATIVISTIC velocities in the MAGNETosphere. This gives rise to non-thermal SYNCHROTRON emission across the electroMAGNETic spectrum. The first discovered, and brightest, system, AR Sco (which is the focus of this paper), shows a white dwarf spin-down consistent with MAGNETic dipole emission in a strongly MAGNETic white dwarf. The polarisation properties of the two systems for which polarimetry has been obtained (AR Sco and eRASSU J191213.9-441044) show spin-modulated polarisation, primarily linear, which remarkably reaches 40% in AR Sco. Furthermore, the Stokes Q and U parameters vary in the same manner as the optical polarisation of the Crab pulsar, consistent with a rotating MAGNETic dipole. These systems are intriguing in that each one seems to show different behaviours (e.g. pulse profiles and light-curve properties), presumably mainly due to different viewing aspect angles. It has recently been postulated that these systems represent a short-lived phase of binary evolution linking asynchronously rotating intermediate polars and synchronous polars.
[abstract 19 / 59] Yes (score: 4) - Title: Relativistic accretion-disc models of Cyg X-1 in the soft state: a case studyAuthors: Luciano Ye, Luigi Foschini,Comments: 11 pages, 1 figure, 5 tablesSubjects: astro-ph.HECreated: 2026-09-23; Updated: 2026-09-24; Datestamp: 2026-09-24
The thermal continuum of Cygnus X-1 in the soft state is often modelled with a multicolour disc in a Newtonian spacetime approximation. That choice is convenient for estimating the inner radius, but it neglects RELATIVISTIC effects near the BLACK HOLE; these are usually restored through colour-correction and boundary-condition factors. Using SUZAKU data from one exemplary observation, we compare this Newtonian description with some fully RELATIVISTIC disc models, keeping the same treatment of absorption, ionised winds, Comptonization and reflection. With the mass, distance and inclination fixed to the best current dynamical values, the Newtonian inner radius is consistent with a high-spin Kerr innermost stable circular orbit. The RELATIVISTIC models do not provide a uniformly better description of the spectrum: some worsen the fit or leave spin, inclination and hardening unconstrained, while the formally best model requires an inclination much larger than the dynamical one or a smaller spin. Apparent tensions with the models arise from data degeneracies and from the limited energy band, not from a failure of general relativity.
[abstract 20 / 59] (score: 3) - Title: Lens Model Accuracy in the Expected LSST Lensed AGN SampleAuthors: Padmavathi Venkatraman, Sydney Erickson, Phil Marshall, Martin Millon, Philip Holloway, Simon Birrer, Steven Dillmann, Xiangyu Huang, Sreevani Jaragula, Ralf Kaehler, Narayan Khadka, Grzegorz Madejski, Ayan Mitra, Kevin Reil, Aaron Roodman, the LSST Dark Energy Science Collaboration,Comments: 30 pages, 14 figures, accepted in AJ, https://iopscience.iop.org/article/10.3847/1538-3881/ae9e2b, data https://zenodo.org/records/17412880 and code https://github.com/padma18-vb/lsst_lensed_agn_modelingSubjects: astro-ph.COCreated: 2026-09-22; Updated: 2026-09-24; Datestamp: 2026-09-24
Strong gravitational lensing of ACTIVE GALACTIC NUCLEi (AGN) enables measurements of cosmological parameters through time-delay cosmography (TDC). With data from the upcoming LSST survey, we anticipate using a sample of O(1000) lensed AGN for TDC. To prepare for this dataset and enable this measurement, we construct and analyze a realistic mock sample of 1300 systems drawn from the OM10 (Oguri & Marshall 2010) catalog of simulated lenses with AGN sources at $z<3.1$ in order to test a key aspect of the analysis pipeline, that of the lens modeling. We realize the lenses as power law elliptical mass distributions and simulate 5-year LSST i-band coadd images. From every image, we infer the lens mass model parameters using neural posterior estimation (NPE). Focusing on the key model parameters, $θ_E$ (the Einstein Radius) and $γ_{lens}$ (the projected mass density profile slope), with consistent mass-light ellipticity correlations in test and training data, we recover $θ_E$ with less than 1% bias per lens, 6.5% precision per lens and $γ_{lens}$ with less than 3% bias per lens, 8% precision per lens. We find that lens light subtraction prior to modeling is only useful when applied to data sampled from the training prior. If emulated deconvolution is applied to the data prior to modeling, precision improves across all parameters by a factor of 2. Finally, we combine the inferred lens mass models using Bayesian Hierarchical Inference to recover the global properties of the lens sample with less than 1% bias.
[abstract 21 / 59] (score: 3) - Title: Direct multi-model dark-matter search with gravitational-wave interferometers using data from the first part of the fourth LIGO-Virgo-KAGRA observing runAuthors: The LIGO Scientific Collaboration, the Virgo Collaboration, the KAGRA Collaboration, A. G. Abac, I. Abouelfettouh, F. Acernese, K. Ackley, C. Adamcewicz, S. Adhicary, D. Adhikari, N. Adhikari, R. X. Adhikari, V. K. Adkins, S. Afroz, A. Agapito, D. Agarwal, M. Agathos, N. Aggarwal, S. Aggarwal, O. D. Aguiar, I. -L. Ahrend, L. Aiello, A. Ain, P. Ajith, T. Akutsu, S. Albanesi, W. Ali, S. Al-Kershi, C. Alléné, A. Allocca, S. Al-Shammari, P. A. Altin, S. Alvarez-Lopez, W. Amar, O. Amarasinghe, A. Amato, F. Amicucci, C. Amra, A. Ananyeva, S. B. Anderson, W. G. Anderson, M. Andia, M. Ando, M. Andrés-Carcasona, T. Andrić, J. Anglin, S. Ansoldi, J. M. Antelis, S. Antier, M. Aoumi, E. Z. Appavuravther, S. Appert, S. K. Apple, K. Arai, A. Araya, M. C. Araya, M. Arca Sedda, J. S. Areeda, N. Aritomi, F. Armato, S. Armstrong, N. Arnaud, M. Arogeti, S. M. Aronson, G. Ashton, Y. Aso, L. Asprea, M. Assiduo, S. Assis de Souza Melo, S. M. Aston, P. Astone, F. Attadio, F. Aubin, K. AultONeal, G. Avallone, E. A. Avila, S. Babak, C. Badger, S. Bae, S. Bagnasco, L. Baiotti, R. Bajpai, T. Baka, A. M. Baker, K. A. Baker, T. Baker, G. Baldi, N. Baldicchi, M. Ball, G. Ballardin, S. W. Ballmer, S. Banagiri, B. Banerjee, D. Bankar, T. M. Baptiste, P. Baral, M. Baratti, J. C. Barayoga, B. C. Barish, D. Barker, N. Barman, P. Barneo, F. Barone, B. Barr, L. Barsotti, M. Barsuglia, D. Barta, A. M. Bartoletti, M. A. Barton, I. Bartos, A. Basalaev, R. Bassiri, A. Basti, M. Bawaj, P. Baxi, J. C. Bayley, A. C. Baylor, P. A. Baynard, M. Bazzan, V. M. Bedakihale, F. Beirnaert, M. Bejger, D. Belardinelli, A. S. Bell, D. S. Bellie, L. Bellizzi, W. Benoit, I. Bentara, J. D. Bentley, M. Ben Yaala, S. Bera, F. Bergamin, B. K. Berger, S. Bernuzzi, M. Beroiz, D. Bersanetti, T. Bertheas, A. Bertolini, J. Betzwieser, D. Beveridge, G. Bevilacqua, N. Bevins, R. Bhandare, R. Bhatt, D. Bhattacharjee, S. Bhattacharyya, S. Bhaumik, V. Biancalana, A. Bianchi, I. A. Bilenko, G. Billingsley, A. Binetti, S. Bini, C. Binu, S. Biot, O. Birnholtz, S. Biscoveanu, A. Bisht, M. Bitossi, M. -A. Bizouard, S. Blaber, J. K. Blackburn, L. A. Blagg, C. D. Blair, D. G. Blair, N. Bode, N. Boettner, G. Boileau, M. Boldrini, G. N. Bolingbroke, A. Bolliand, L. D. Bonavena, R. Bondarescu, F. Bondu, E. Bonilla, M. S. Bonilla, A. Bonino, R. Bonnand, A. Borchers, V. Boschi, S. Bose, V. Bossilkov, Y. Bothra, A. Boudon, L. Bourg, M. Boyle, A. Bozzi, C. Bradaschia, P. R. Brady, A. Branch, M. Branchesi, I. Braun, T. Briant, A. Brillet, M. Brinkmann, P. Brockill, E. Brockmueller, A. F. Brooks, B. C. Brown, D. D. Brown, M. L. Brozzetti, S. Brunett, G. Bruno, R. Bruntz, J. Bryant, Y. Bu, F. Bucci, J. Buchanan, O. Bulashenko, T. Bulik, H. J. Bulten, A. Buonanno, K. Burtnyk, R. Buscicchio, D. Buskulic, C. Buy, R. L. Byer, G. S. Cabourn Davies, R. Cabrita, V. Cáceres-Barbosa, L. Cadonati, G. Cagnoli, C. Cahillane, A. Calafat, T. A. Callister, E. Calloni, S. R. Callos, G. Caneva Santoro, K. C. Cannon, H. Cao, L. A. Capistran, E. Capocasa, E. Capote, G. Capurri, G. Carapella, F. Carbognani, M. Carlassara, J. B. Carlin, T. K. Carlson, M. F. Carney, M. Carpinelli, G. Carrillo, J. J. Carter, G. Carullo, A. Casallas-Lagos, J. Casanueva Diaz, C. Casentini, S. Y. Castro-Lucas, S. Caudill, M. Cavaglià, R. Cavalieri, A. Ceja, G. Cella, P. Cerdá-Durán, E. Cesarini, N. Chabbra, W. Chaibi, A. Chakraborty, P. Chakraborty, S. Chakraborty, S. Chalathadka Subrahmanya, J. C. L. Chan, M. Chan, K. Chang, S. Chao, P. Charlton, E. Chassande-Mottin, C. Chatterjee, Debarati Chatterjee, Deep Chatterjee, M. Chaturvedi, S. Chaty, A. Chen, A. H. -Y. Chen, D. Chen, H. Chen, H. Y. Chen, S. Chen, Yanbei Chen, Yitian Chen, H. P. Cheng, P. Chessa, H. T. Cheung, S. Y. Cheung, F. Chiadini, G. Chiarini, A. Chiba, A. Chincarini, M. L. Chiofalo, A. Chiummo, C. Chou, S. Choudhary, N. Christensen, S. S. Y. Chua, G. Ciani, P. Ciecielag, M. Cieślar, M. Cifaldi, B. Cirok, F. Clara, J. A. Clark, T. A. Clarke, P. Clearwater, S. Clesse, F. Cleva, E. Coccia, E. Codazzo, P. -F. Cohadon, S. Colace, E. Colangeli, M. Colleoni, C. G. Collette, J. Collins, S. Colloms, A. Colombo, C. M. Compton, G. Connolly, L. Conti, T. R. Corbitt, I. Cordero-Carrión, S. Corezzi, N. J. Cornish, I. Coronado, A. Corsi, R. Cottingham, M. W. Coughlin, A. Couineaux, P. Couvares, D. M. Coward, R. Coyne, A. Cozzumbo, J. D. E. Creighton, T. D. Creighton, P. Cremonese, S. Crook, R. Crouch, J. Csizmazia, J. R. Cudell, T. J. Cullen, A. Cumming, E. Cuoco, M. Cusinato, L. V. Da Conceição, T. Dal Canton, S. Dal Pra, G. Dálya, B. D'Angelo, S. Danilishin, S. D'Antonio, K. Danzmann, K. E. Darroch, L. P. Dartez, R. Das, A. Dasgupta, V. Dattilo, A. Daumas, N. Davari, I. Dave, A. Davenport, M. Davier, T. F. Davies, D. Davis, L. Davis, M. C. Davis, P. Davis, E. J. Daw, M. Dax, J. De Bolle, M. Deenadayalan, J. Degallaix, M. De Laurentis, F. De Lillo, S. Della Torre, W. Del Pozzo, A. Demagny, F. De Marco, G. Demasi, F. De Matteis, N. Demos, T. Dent, A. Depasse, N. DePergola, R. De Pietri, R. De Rosa, C. De Rossi, M. Desai, R. DeSalvo, A. DeSimone, R. De Simone, A. Dhani, R. Diab, M. C. Díaz, M. Di Cesare, G. Dideron, T. Dietrich, L. Di Fiore, C. Di Fronzo, M. Di Giovanni, T. Di Girolamo, D. Diksha, J. Ding, S. Di Pace, I. Di Palma, D. Di Piero, F. Di Renzo, Divyajyoti, A. Dmitriev, J. P. Docherty, Z. Doctor, N. Doerksen, E. Dohmen, A. Doke, A. Domiciano De Souza, L. D'Onofrio, F. Donovan, K. L. Dooley, T. Dooney, S. Doravari, O. Dorosh, W. J. D. Doyle, M. Drago, J. C. Driggers, L. Dunn, U. Dupletsa, P. -A. Duverne, D. D'Urso, P. Dutta Roy, H. Duval, S. E. Dwyer, C. Eassa, M. Ebersold, T. Eckhardt, G. Eddolls, A. Effler, J. Eichholz, H. Einsle, M. Eisenmann, M. Emma, K. Endo, R. Enficiaud, L. Errico, R. Espinosa, M. Esposito, R. C. Essick, H. Estellés, T. Etzel, M. Evans, T. Evstafyeva, B. E. Ewing, J. M. Ezquiaga, F. Fabrizi, V. Fafone, S. Fairhurst, A. M. Farah, B. Farr, W. M. Farr, G. Favaro, M. Favata, M. Fays, M. Fazio, J. Feicht, M. M. Fejer, R. Felicetti, E. Fenyvesi, J. Fernandes, T. Fernandes, D. Fernando, S. Ferraiuolo, T. A. Ferreira, F. Fidecaro, P. Figura, A. Fiori, I. Fiori, M. Fishbach, R. P. Fisher, R. Fittipaldi, V. Fiumara, R. Flaminio, S. M. Fleischer, L. S. Fleming, E. Floden, H. Fong, J. A. Font, F. Fontinele-Nunes, C. Foo, B. Fornal, K. Franceschetti, F. Frappez, S. Frasca, F. Frasconi, J. P. Freed, Z. Frei, A. Freise, O. Freitas, R. Frey, W. Frischhertz, P. Fritschel, V. V. Frolov, G. G. Fronzé, M. Fuentes-Garcia, S. Fujii, T. Fujimori, P. Fulda, M. Fyffe, B. Gadre, J. R. Gair, S. Galaudage, V. Galdi, R. Gamba, A. Gamboa, S. Gamoji, D. Ganapathy, A. Ganguly, B. Garaventa, J. García-Bellido, C. García-Quirós, J. W. Gardner, K. A. Gardner, S. Garg, J. Gargiulo, X. Garrido, A. Garron, F. Garufi, P. A. Garver, C. Gasbarra, B. Gateley, F. Gautier, V. Gayathri, T. Gayer, G. Gemme, A. Gennai, V. Gennari, J. George, R. George, O. Gerberding, L. Gergely, Archisman Ghosh, Sayantan Ghosh, Shaon Ghosh, Shrobana Ghosh, Suprovo Ghosh, Tathagata Ghosh, J. A. Giaime, K. D. Giardina, D. R. Gibson, C. Gier, S. Gkaitatzis, J. Glanzer, F. Glotin, J. Godfrey, R. V. Godley, P. Godwin, A. S. Goettel, E. Goetz, J. Golomb, S. Gomez Lopez, B. Goncharov, G. González, P. Goodarzi, S. Goode, A. W. Goodwin-Jones, M. Gosselin, R. Gouaty, D. W. Gould, K. Govorkova, A. Grado, V. Graham, A. E. Granados, M. Granata, V. Granata, S. Gras, P. Grassia, J. Graves, C. Gray, R. Gray, G. Greco, A. C. Green, L. Green, S. M. Green, S. R. Green, C. Greenberg, A. M. Gretarsson, H. K. Griffin, D. Griffith, H. L. Griggs, G. Grignani, C. Grimaud, H. Grote, S. Grunewald, D. Guerra, D. Guetta, G. M. Guidi, A. R. Guimaraes, H. K. Gulati, F. Gulminelli, H. Guo, W. Guo, Y. Guo, Anuradha Gupta, I. Gupta, N. C. Gupta, S. K. Gupta, V. Gupta, N. Gupte, J. Gurs, N. Gutierrez, N. Guttman, F. Guzman, D. Haba, M. Haberland, S. Haino, E. D. Hall, E. Z. Hamilton, G. Hammond, M. Haney, J. Hanks, C. Hanna, M. D. Hannam, O. A. Hannuksela, A. G. Hanselman, H. Hansen, J. Hanson, S. Hanumasagar, R. Harada, A. R. Hardison, S. Harikumar, K. Haris, I. Harley-Trochimczyk, T. Harmark, J. Harms, G. M. Harry, I. W. Harry, J. Hart, B. Haskell, C. J. Haster, K. Haughian, H. Hayakawa, K. Hayama, M. C. Heintze, J. Heinze, J. Heinzel, H. Heitmann, F. Hellman, A. F. Helmling-Cornell, G. Hemming, O. Henderson-Sapir, M. Hendry, I. S. Heng, M. H. Hennig, C. Henshaw, M. Heurs, A. L. Hewitt, J. Heynen, J. Heyns, S. Higginbotham, S. Hild, S. Hill, Y. Himemoto, N. Hirata, C. Hirose, D. Hofman, B. E. Hogan, N. A. Holland, I. J. Hollows, D. E. Holz, L. Honet, D. J. Horton-Bailey, J. Hough, S. Hourihane, N. T. Howard, E. J. Howell, C. G. Hoy, C. A. Hrishikesh, P. Hsi, H. -F. Hsieh, H. -Y. Hsieh, C. Hsiung, S. -H. Hsu, W. -F. Hsu, Q. Hu, H. Y. Huang, Y. Huang, Y. T. Huang, A. D. Huddart, B. Hughey, V. Hui, S. Husa, R. Huxford, L. Iampieri, G. A. Iandolo, M. Ianni, G. Iannone, J. Iascau, K. Ide, R. Iden, A. Ierardi, S. Ikeda, H. Imafuku, Y. Inoue, G. Iorio, P. Iosif, M. H. Iqbal, J. Irwin, R. Ishikawa, M. Isi, K. S. Isleif, Y. Itoh, M. Iwaya, B. R. Iyer, C. Jacquet, P. -E. Jacquet, T. Jacquot, S. J. Jadhav, S. P. Jadhav, M. Jain, T. Jain, A. L. James, K. Jani, J. Janquart, N. N. Janthalur, S. Jaraba, P. Jaranowski, R. Jaume, W. Javed, A. Jennings, M. Jensen, W. Jia, J. Jiang, H. -B. Jin, G. R. Johns, N. A. Johnson, M. C. Johnston, R. Johnston, N. Johny, D. H. Jones, D. I. Jones, R. Jones, H. E. Jose, P. Joshi, S. K. Joshi, G. Joubert, J. Ju, L. Ju, K. Jung, J. Junker, V. Juste, H. B. Kabagoz, T. Kajita, I. Kaku, V. Kalogera, M. Kalomenopoulos, M. Kamiizumi, N. Kanda, S. Kandhasamy, G. Kang, N. C. Kannachel, J. B. Kanner, S. A. KantiMahanty, S. J. Kapadia, D. P. Kapasi, M. Karthikeyan, M. Kasprzack, H. Kato, T. Kato, E. Katsavounidis, W. Katzman, R. Kaushik, K. Kawabe, R. Kawamoto, D. Keitel, L. J. Kemperman, J. Kennington, F. A. Kerkow, R. Kesharwani, J. S. Key, R. Khadela, S. Khadka, S. S. Khadkikar, F. Y. Khalili, F. Khan, T. Khanam, M. Khursheed, N. M. Khusid, W. Kiendrebeogo, N. Kijbunchoo, C. Kim, J. C. Kim, K. Kim, M. H. Kim, S. Kim, Y. -M. Kim, C. Kimball, K. Kimes, M. Kinnear, J. S. Kissel, S. Klimenko, A. M. Knee, E. J. Knox, N. Knust, K. Kobayashi, S. M. Koehlenbeck, G. Koekoek, K. Kohri, K. Kokeyama, S. Koley, P. Kolitsidou, A. E. Koloniari, K. Komori, A. K. H. Kong, A. Kontos, L. M. Koponen, M. Korobko, X. Kou, A. Koushik, N. Kouvatsos, M. Kovalam, T. Koyama, D. B. Kozak, S. L. Kranzhoff, V. Kringel, N. V. Krishnendu, S. Kroker, A. Królak, K. Kruska, J. Kubisz, G. Kuehn, S. Kulkarni, A. Kulur Ramamohan, Achal Kumar, Anil Kumar, Praveen Kumar, Prayush Kumar, Rahul Kumar, Rakesh Kumar, J. Kume, K. Kuns, N. Kuntimaddi, S. Kuroyanagi, S. Kuwahara, K. Kwak, K. Kwan, S. Kwon, G. Lacaille, D. Laghi, A. H. Laity, E. Lalande, M. Lalleman, P. C. Lalremruati, M. Landry, B. B. Lane, R. N. Lang, J. Lange, R. Langgin, B. Lantz, I. La Rosa, J. Larsen, A. Lartaux-Vollard, P. D. Lasky, J. Lawrence, M. Laxen, C. Lazarte, A. Lazzarini, C. Lazzaro, P. Leaci, L. Leali, Y. K. Lecoeuche, H. M. Lee, H. W. Lee, J. Lee, K. Lee, R. -K. Lee, R. Lee, Sungho Lee, Sunjae Lee, Y. Lee, I. N. Legred, J. Lehmann, L. Lehner, M. Le Jean, A. Lemaître, M. Lenti, M. Leonardi, M. Lequime, N. Leroy, M. Lesovsky, N. Letendre, M. Lethuillier, Y. Levin, K. Leyde, A. K. Y. Li, K. L. Li, T. G. F. Li, X. Li, Y. Li, Z. Li, A. Lihos, E. T. Lin, F. Lin, L. C. -C. Lin, Y. -C. Lin, C. Lindsay, S. D. Linker, A. Liu, G. C. Liu, Jian Liu, F. Llamas Villarreal, J. Llobera-Querol, R. K. L. Lo, J. -P. Locquet, S. C. G. Loggins, M. R. Loizou, L. T. London, A. Longo, D. Lopez, M. Lopez Portilla, A. Lorenzo-Medina, V. Loriette, M. Lormand, G. Losurdo, E. Lotti, T. P. Lott, J. D. Lough, H. A. Loughlin, C. O. Lousto, N. Low, N. Lu, L. Lucchesi, H. Lück, D. Lumaca, A. P. Lundgren, A. W. Lussier, R. Macas, M. MacInnis, D. M. Macleod, I. A. O. MacMillan, A. Macquet, K. Maeda, S. Maenaut, S. S. Magare, R. M. Magee, E. Maggio, R. Maggiore, M. Magnozzi, M. Mahesh, M. Maini, S. Majhi, E. Majorana, C. N. Makarem, D. Malakar, J. A. Malaquias-Reis, U. Mali, S. Maliakal, A. Malik, L. Mallick, A. -K. Malz, N. Man, M. Mancarella, V. Mandic, V. Mangano, B. Mannix, G. L. Mansell, M. Manske, M. Mantovani, M. Mapelli, C. Marinelli, F. Marion, A. S. Markosyan, A. Markowitz, E. Maros, S. Marsat, F. Martelli, I. W. Martin, R. M. Martin, B. B. Martinez, D. A. Martinez, M. Martinez, V. Martinez, A. Martini, J. C. Martins, D. V. Martynov, E. J. Marx, L. Massaro, A. Masserot, M. Masso-Reid, S. Mastrogiovanni, T. Matcovich, M. Matiushechkina, L. Maurin, N. Mavalvala, N. Maxwell, G. McCarrol, R. McCarthy, D. E. McClelland, S. McCormick, L. McCuller, S. McEachin, C. McElhenny, G. I. McGhee, J. McGinn, K. B. M. McGowan, J. McIver, A. McLeod, I. McMahon, T. McRae, R. McTeague, D. Meacher, B. N. Meagher, R. Mechum, Q. Meijer, A. Melatos, C. S. Menoni, F. Mera, R. A. Mercer, L. Mereni, K. Merfeld, E. L. Merilh, J. R. Mérou, J. D. Merritt, M. Merzougui, C. Messick, B. Mestichelli, M. Meyer-Conde, F. Meylahn, A. Mhaske, A. Miani, H. Miao, C. Michel, Y. Michimura, H. Middleton, D. P. Mihaylov, A. L. Miller, S. J. Miller, M. Millhouse, E. Milotti, V. Milotti, Y. Minenkov, E. M. Minihan, Ll. M. Mir, L. Mirasola, M. Miravet-Tenés, C. -A. Miritescu, A. Mishra, C. Mishra, T. Mishra, A. L. Mitchell, J. G. Mitchell, S. Mitra, V. P. Mitrofanov, K. Mitsuhashi, R. Mittleman, O. Miyakawa, S. Miyoki, A. Miyoko, G. Mo, L. Mobilia, S. R. P. Mohapatra, S. R. Mohite, M. Molina-Ruiz, M. Mondin, M. Montani, C. J. Moore, D. Moraru, A. More, S. More, C. Moreno, E. A. Moreno, G. Moreno, A. Moreso Serra, S. Morisaki, Y. Moriwaki, G. Morras, A. Moscatello, M. Mould, B. Mours, C. M. Mow-Lowry, L. Muccillo, F. Muciaccia, D. Mukherjee, Samanwaya Mukherjee, Soma Mukherjee, Subroto Mukherjee, Suvodip Mukherjee, N. Mukund, A. Mullavey, H. Mullock, J. Mundi, C. L. Mungioli, M. Murakoshi, P. G. Murray, D. Nabari, S. L. Nadji, A. Nagar, N. Nagarajan, K. Nakagaki, K. Nakamura, H. Nakano, M. Nakano, D. Nanadoumgar-Lacroze, D. Nandi, V. Napolano, P. Narayan, I. Nardecchia, T. Narikawa, H. Narola, L. Naticchioni, R. K. Nayak, L. Negri, A. Nela, C. Nelle, A. Nelson, T. J. N. Nelson, M. Nery, A. Neunzert, S. Ng, L. Nguyen Quynh, S. A. Nichols, A. B. Nielsen, Y. Nishino, A. Nishizawa, S. Nissanke, W. Niu, F. Nocera, J. Noller, M. Norman, C. North, J. Novak, R. Nowicki, J. F. Nuño Siles, L. K. Nuttall, K. Obayashi, J. Oberling, J. O'Dell, E. Oelker, M. Oertel, G. Oganesyan, T. O'Hanlon, M. Ohashi, F. Ohme, R. Oliveri, R. Omer, B. O'Neal, M. Onishi, K. Oohara, B. O'Reilly, M. Orselli, R. O'Shaughnessy, S. O'Shea, S. Oshino, C. Osthelder, I. Ota, D. J. Ottaway, A. Ouzriat, H. Overmier, B. J. Owen, R. Ozaki, A. E. Pace, R. Pagano, M. A. Page, A. Pai, L. Paiella, A. Pal, S. Pal, M. A. Palaia, M. Pálfi, P. P. Palma, C. Palomba, P. Palud, H. Pan, J. Pan, K. C. Pan, P. K. Panda, Shiksha Pandey, Swadha Pandey, P. T. H. Pang, F. Pannarale, K. A. Pannone, B. C. Pant, F. H. Panther, M. Panzeri, F. Paoletti, A. Paolone, A. Papadopoulos, E. E. Papalexakis, L. Papalini, G. Papigkiotis, A. Paquis, A. Parisi, B. -J. Park, J. Park, W. Parker, G. Pascale, D. Pascucci, A. Pasqualetti, R. Passaquieti, L. Passenger, D. Passuello, O. Patane, A. V. Patel, D. Pathak, A. Patra, B. Patricelli, B. G. Patterson, K. Paul, S. Paul, E. Payne, T. Pearce, M. Pedraza, A. Pele, F. E. Peña Arellano, X. Peng, Y. Peng, S. Penn, M. D. Penuliar, A. Perego, Z. Pereira, C. Périgois, G. Perna, A. Perreca, J. Perret, S. Perriès, J. W. Perry, D. Pesios, S. Peters, S. Petracca, C. Petrillo, H. P. Pfeiffer, H. Pham, K. A. Pham, K. S. Phukon, H. Phurailatpam, M. Piarulli, L. Piccari, O. J. Piccinni, M. Pichot, M. Piendibene, F. Piergiovanni, L. Pierini, G. Pierra, V. Pierro, M. Pietrzak, M. Pillas, F. Pilo, L. Pinard, I. M. Pinto, M. Pinto, B. J. Piotrzkowski, M. Pirello, M. D. Pitkin, A. Placidi, E. Placidi, M. L. Planas, W. Plastino, C. Plunkett, R. Poggiani, E. Polini, J. Pomper, L. Pompili, J. Poon, E. Porcelli, E. K. Porter, C. Posnansky, R. Poulton, J. Powell, G. S. Prabhu, M. Pracchia, B. K. Pradhan, T. Pradier, A. K. Prajapati, K. Prasai, R. Prasanna, P. Prasia, G. Pratten, G. Principe, G. A. Prodi, P. Prosperi, P. Prosposito, A. C. Providence, A. Puecher, J. Pullin, P. Puppo, M. Pürrer, H. Qi, M. Qiao, J. Qin, G. Quéméner, V. Quetschke, P. J. Quinonez, N. Qutob, R. Rading, I. Rainho, S. Raja, C. Rajan, B. Rajbhandari, K. E. Ramirez, F. A. Ramis Vidal, M. Ramos Arevalo, A. Ramos-Buades, S. Ranjan, K. Ransom, P. Rapagnani, B. Ratto, A. Ravichandran, A. Ray, V. Raymond, M. Razzano, J. Read, T. Regimbau, S. Reid, C. Reissel, D. H. Reitze, V. Rella, A. I. Renzini, B. Revenu, A. Revilla Peña, R. Reyes, L. Ricca, F. Ricci, M. Ricci, A. Ricciardone, J. Rice, J. W. Richardson, M. L. Richardson, A. Rijal, K. Riles, H. K. Riley, S. Rinaldi, J. Rittmeyer, C. Robertson, F. Robinet, M. Robinson, A. Rocchi, L. Rolland, J. G. Rollins, A. E. Romano, R. Romano, A. Romero, I. M. Romero-Shaw, J. H. Romie, S. Ronchini, T. J. Roocke, L. Rosa, T. J. Rosauer, C. A. Rose, D. Rosińska, M. P. Ross, M. Rossello-Sastre, S. Rowan, S. K. Roy, S. Roy, D. Rozza, P. Ruggi, N. Ruhama, E. Ruiz Morales, K. Ruiz-Rocha, S. Sachdev, T. Sadecki, P. Saffarieh, S. Safi-Harb, M. R. Sah, S. Saha, T. Sainrat, S. Sajith Menon, K. Sakai, Y. Sakai, M. Sakellariadou, S. Sakon, O. S. Salafia, F. Salces-Carcoba, L. Salconi, M. Saleem, F. Salemi, M. Sallé, S. U. Salunkhe, S. Salvador, A. Salvarese, A. Samajdar, A. Sanchez, E. J. Sanchez, L. E. Sanchez, N. Sanchis-Gual, J. R. Sanders, E. M. Sänger, F. Santoliquido, F. Sarandrea, T. R. Saravanan, N. Sarin, P. Sarkar, A. Sasli, P. Sassi, B. Sassolas, B. S. Sathyaprakash, R. Sato, S. Sato, Yukino Sato, Yu Sato, O. Sauter, R. L. Savage, T. Sawada, H. L. Sawant, S. Sayah, V. Scacco, D. Schaetzl, M. Scheel, A. Schiebelbein, M. G. Schiworski, P. Schmidt, S. Schmidt, R. Schnabel, M. Schneewind, R. M. S. Schofield, K. Schouteden, B. W. Schulte, B. F. Schutz, E. Schwartz, M. Scialpi, J. Scott, S. M. Scott, R. M. Sedas, T. C. Seetharamu, M. Seglar-Arroyo, Y. Sekiguchi, D. Sellers, N. Sembo, A. S. Sengupta, E. G. Seo, J. W. Seo, V. Sequino, M. Serra, A. Sevrin, T. Shaffer, U. S. Shah, M. A. Shaikh, L. Shao, A. K. Sharma, Preeti Sharma, Prianka Sharma, Ritwik Sharma, S. Sharma Chaudhary, P. Shawhan, N. S. Shcheblanov, E. Sheridan, Z. -H. Shi, M. Shikauchi, R. Shimomura, H. Shinkai, S. Shirke, D. H. Shoemaker, D. M. Shoemaker, R. W. Short, S. ShyamSundar, A. Sider, H. Siegel, D. Sigg, L. Silenzi, L. Silvestri, M. Simmonds, L. P. Singer, Amitesh Singh, Anika Singh, D. Singh, N. Singh, S. Singh, A. M. Sintes, V. Sipala, V. Skliris, B. J. J. Slagmolen, D. A. Slater, T. J. Slaven-Blair, J. Smetana, J. R. Smith, L. Smith, R. J. E. Smith, W. J. Smith, S. Soares de Albuquerque Filho, M. Soares-Santos, K. Somiya, I. Song, S. Soni, V. Sordini, F. Sorrentino, H. Sotani, F. Spada, V. Spagnuolo, A. P. Spencer, P. Spinicelli, A. K. Srivastava, F. Stachurski, C. J. Stark, D. A. Steer, N. Steinle, J. Steinlechner, S. Steinlechner, N. Stergioulas, P. Stevens, M. StPierre, M. D. Strong, A. Strunk, A. L. Stuver, M. Suchenek, S. Sudhagar, Y. Sudo, N. Sueltmann, L. Suleiman, K. D. Sullivan, J. Sun, L. Sun, S. Sunil, J. Suresh, B. J. Sutton, P. J. Sutton, K. Suzuki, M. Suzuki, B. L. Swinkels, A. Syx, M. J. Szczepańczyk, P. Szewczyk, M. Tacca, H. Tagoshi, K. Takada, H. Takahashi, R. Takahashi, A. Takamori, S. Takano, H. Takeda, K. Takeshita, I. Takimoto Schmiegelow, M. Takou-Ayaoh, C. Talbot, M. Tamaki, N. Tamanini, D. Tanabe, K. Tanaka, S. J. Tanaka, S. Tanioka, D. B. Tanner, W. Tanner, L. Tao, R. D. Tapia, E. N. Tapia San Martín, C. Taranto, A. Taruya, J. D. Tasson, J. G. Tau, D. Tellez, R. Tenorio, H. Themann, A. Theodoropoulos, M. P. Thirugnanasambandam, L. M. Thomas, M. Thomas, P. Thomas, J. E. Thompson, S. R. Thondapu, K. A. Thorne, E. Thrane, J. Tissino, A. Tiwari, Pawan Tiwari, Praveer Tiwari, S. Tiwari, V. Tiwari, M. R. Todd, M. Toffano, A. M. Toivonen, K. Toland, A. E. Tolley, T. Tomaru, V. Tommasini, T. Tomura, H. Tong, C. Tong-Yu, A. Torres-Forné, C. I. Torrie, I. Tosta e Melo, E. Tournefier, M. Trad Nery, K. Tran, A. Trapananti, R. Travaglini, F. Travasso, G. Traylor, M. Trevor, M. C. Tringali, A. Tripathee, G. Troian, A. Trovato, L. Trozzo, R. J. Trudeau, T. Tsang, S. Tsuchida, L. Tsukada, K. Turbang, M. Turconi, C. Turski, H. Ubach, T. Uchiyama, R. P. Udall, T. Uehara, K. Ueno, V. Undheim, L. E. Uronen, T. Ushiba, M. Vacatello, H. Vahlbruch, N. Vaidya, G. Vajente, A. Vajpeyi, J. Valencia, M. Valentini, S. A. Vallejo-Peña, S. Vallero, V. Valsan, M. van Dael, E. Van den Bossche, J. F. J. van den Brand, C. Van Den Broeck, M. van der Sluys, A. Van de Walle, J. van Dongen, K. Vandra, M. VanDyke, H. van Haevermaet, J. V. van Heijningen, P. Van Hove, J. Vanier, M. VanKeuren, J. Vanosky, N. van Remortel, M. Vardaro, A. F. Vargas, V. Varma, A. N. Vazquez, A. Vecchio, G. Vedovato, J. Veitch, P. J. Veitch, S. Venikoudis, R. C. Venterea, P. Verdier, M. Vereecken, D. Verkindt, B. Verma, Y. Verma, S. M. Vermeulen, F. Vetrano, A. Veutro, A. Viceré, S. Vidyant, A. D. Viets, A. Vijaykumar, A. Vilkha, N. Villanueva Espinosa, V. Villa-Ortega, E. T. Vincent, J. -Y. Vinet, S. Viret, S. Vitale, H. Vocca, D. Voigt, E. R. G. von Reis, J. S. A. von Wrangel, W. E. Vossius, L. Vujeva, S. P. Vyatchanin, J. Wack, L. E. Wade, M. Wade, K. J. Wagner, L. Wallace, E. J. Wang, H. Wang, J. Z. Wang, W. H. Wang, Y. F. Wang, G. Waratkar, J. Warner, M. Was, T. Washimi, N. Y. Washington, D. Watarai, B. Weaver, S. A. Webster, N. L. Weickhardt, M. Weinert, A. J. Weinstein, R. Weiss, L. Wen, K. Wette, J. T. Whelan, B. F. Whiting, C. Whittle, E. G. Wickens, D. Wilken, A. T. Wilkin, B. M. Williams, D. Williams, M. J. Williams, N. S. Williams, J. L. Willis, B. Willke, M. Wils, L. Wilson, C. W. Winborn, J. Winterflood, C. C. Wipf, G. Woan, J. Woehler, N. E. Wolfe, H. T. Wong, I. C. F. Wong, K. Wong, T. Wouters, J. L. Wright, M. Wright, B. Wu, C. Wu, D. S. Wu, H. Wu, K. Wu, Q. Wu, Y. Wu, Z. Wu, E. Wuchner, D. M. Wysocki, V. A. Xu, Y. Xu, N. Yadav, H. Yamamoto, K. Yamamoto, T. S. Yamamoto, T. Yamamoto, R. Yamazaki, T. Yan, F. Yang, K. Z. Yang, Y. Yang, Z. Yarbrough, J. Yebana, S. -W. Yeh, A. B. Yelikar, X. Yin, J. Yokoyama, T. Yokozawa, S. Yuan, H. Yuzurihara, M. Zanolin, M. Zeeshan, T. Zelenova, J. -P. Zendri, M. Zeoli, M. Zerrad, M. Zevin, L. Zhang, N. Zhang, R. Zhang, T. Zhang, C. Zhao, Yue Zhao, Yuhang Zhao, Z. -C. Zhao, Y. Zheng, H. Zhong, H. Zhou, H. O. Zhu, Z. -H. Zhu, A. B. Zimmerman, L. Zimmermann, M. E. Zucker, J. Zweizig, J. Shu,Comments: 9 pages, 1 figure (+1 figure in appendix)Subjects: astro-ph.CO gr-qcCreated: 2026-09-22; Updated: 2026-09-24; Datestamp: 2026-09-24
We search data from the first part of the fourth observing run of LIGO--Virgo--KAGRA for three kinds of DARK MATTER -- dilatons (spin-0), dark photons (spin-1) and tensor BOSONs (spin-2) -- using three independent methods, each extended to find all three candidates. Each candidate can interact with different standard-model particles in the instruments, causing unique differential strains. We find no evidence for a signal and place the most stringent limits to date on their couplings to the interferometers. For scalars with masses $[4\times 10^{-14},1.5\times 10^{-13}]$ eV coupling to photons or electrons, our constraints improve upon those from the third observing run by an order of magnitude, reaching $\sim 10^{-20},\text{GeV}^{-1}$. For vectors with masses $[7\times 10^{-13},8.47\times 10^{-12}]$ eV coupling to baryons, our constraints supersede those from MICROSCOPE and Eot-Wash by one to two orders of magnitude, reaching $\sim 5\times 10^{-24}$ at $\sim 10^{-12}$ eV. For tensors with masses $[4\times 10^{-14},8.47\times 10^{-12}]$ eV coupling via a Yukawa interaction, we obtain the first constraints from gravitational-wave interferometers, surpassing fifth-force experiments by four to five orders of magnitude and reaching $\sim 8\times 10^{-9}$ at $\sim2\times 10^{-13}$ eV. Each method has substantially different sensitivity to each candidate, highlighting the importance of a multi-method approach to search for new physics. Our results demonstrate that gravitational-wave interferometers can simultaneously probe multiple ultralight dark-matter models and place unprecedented constraints on tensor fields arising in a broad range of modified-gravity theories.
[abstract 22 / 59] (score: 3) - Title: Turbulent Dynamo Action in Binary Neutron Star MergersAuthors: Eduardo M. Gutiérrez, David Radice, Jacob Fields, James M. Stone,Comments: 8 pages; 4 figures. Supplemental Material: 8 pages; 8 figures. Accepted for publication in Phys. Rev. LettSubjects: astro-ph.HE gr-qcCreated: 2026-09-22; Updated: 2026-09-24; Datestamp: 2026-09-24
We perform general-RELATIVISTIC MAGNETohydrodynamics zoom-in simulations of the merger of two neutron stars starting with pulsar-like realistic initial MAGNETic field. We employ unprecedented grid resolution down to $Δx \simeq 2.9~{\rm m}$. We find rapid amplification of the MAGNETic energy at small scales, and demonstrate the action of a small-scale turbulent dynamo. We find evidence that ordered large-scale MAGNETic structures emerge already during the early post-merger evolution. These results indicate that strong MAGNETic fields can be established promptly after merger, with important consequences for the electroMAGNETic counterparts of binary neutron star mergers.
[abstract 23 / 59] (score: 3) - Title: Black Hole Occupation Fraction: Dependence on Black Hole Mass Threshold, Environment, Resolution and RedshiftAuthors: Emanuele Contini, J. K. Jang, Jinsu Rhee, Changjo Seo, Sukyoung K. Yi,Comments: 19 pages, 8 figures. Accepted for publication in ApJ after moderate revisionSubjects: astro-ph.GACreated: 2026-09-23; Updated: 2026-09-24; Datestamp: 2026-09-24
We take advantage of the state-of-the-art semi-analytic model \texttt{FEGA25} \citep{contini2025}, run on merger trees extracted from three DARK MATTER-only cosmological simulations, to study the relation between the BLACK HOLE (BH) occupation fraction, $f_{\rm BH,occ}$, and galaxy stellar mass as a function of BH mass threshold, galaxy type, simulated volume, numerical resolution, sampled galaxy population, and redshift. \texttt{FEGA25} includes an improved treatment of ACTIVE GALACTIC NUCLEus feedback and does not impose a pre-existing BH seed population: BHs grow naturally through QUASAR and radio modes. Starting from the prerequisite that \texttt{FEGA25} reproduces the observed BH mass function from at least $z=2$ to the present day, our analysis leads to several results. We find that $f_{\rm BH,occ}$ increases with stellar mass, but that its normalization and shape depend strongly on the adopted BH mass threshold and on the relative contribution of central and satellite galaxies. The relative behavior of central and satellite galaxies depends on the simulation box and BH mass threshold, while the global relation should be interpreted as a population-weighted quantity. We also find significant box-to-box variations, reflecting the combined impact of numerical resolution, simulated volume, and sampled galaxy population. The redshift evolution is not universal: YS50 and the \texttt{NewCluster} zoom-in simulation show a trend qualitatively similar to that reported by \citet{tremmel2024}, whereas larger-volume boxes show the opposite behavior. Finally, comparison with other studies shows that the inferred occupation fraction is highly sensitive to BH mass threshold, simulated volume, numerical resolution, and sampled galaxy population.
[abstract 24 / 59] (score: 3) - Title: A targeted search for fast radio bursts from MAGNETars in elliptical galaxiesAuthors: S. Paine, D. R. Lorimer, S. Sirota, G. M. Doskoch, S. Tabassum, M. Flanagan, J. Lituchy, A. Stone, J. W. Kania, M. Bhardwaj, S. Mehta, M. A. McLaughlin, B. Kharel, D. Agarwal, M. P. Surnis,Comments: 12 pages, 8 figuresSubjects: astro-ph.HE astro-ph.GACreated: 2026-09-22; Updated: 2026-09-24; Datestamp: 2026-09-24
Motivated by predictions that globular clusters associated with nearby giant elliptical galaxies are prime environments for detecting fast radio bursts (FRBs) from MAGNETars, we report on a targeted high-sensitivity search across five local massive elliptical galaxies. We utilized the GREENBURST single-pulse search pipeline and the VEGAS backend on the Green Bank Telescope (GBT) to conduct an L-band (1.4 GHz) survey for FRBs in each target environment. We discovered FRB 20240817A in the direction of M49 (NGC 4472) which has a pulse width of 15 ms, a signal-to-noise ratio of 13, and a dispersion measure (DM) of $983~\rm{cm}^{-3}$ pc. Although a Bayesian spatial association framework initially flags M49 as the host, carefully accounting for the foreground electron column contributions from the Milky Way and both the Virgo intracluster medium and M49's hot gaseous halo ($\sim300-400~\rm{cm}^{-3}$ pc combined) strongly disfavours a physical connection. We conclude that FRB 20240817A is a background event. We also identified a repeating cluster of three low-significance pulses from the direction of M49 at a physically plausible DM of $150-160~\rm{cm}^{-3}$ pc. Accounting for the fraction of each target's extended globular cluster distribution observed, the absence of unambiguous, host-localized bursts allows us to place a joint upper limit on the intrinsic burst rate of a single active source within these systems of $R_0 < 0.028~\rm{hr}^{-1}$ (and an integrated rate limit of $<1.0$~hr$^{-1}$ for M49), lowering previous upper limits and suggesting that MAGNETar formation within dynamical clusters is less efficient than previously assumed.
[abstract 25 / 59] (score: 3) - Title: Reconnection of Gravitational FieldsAuthors: Luca Comisso, Felipe A. Asenjo,Comments: To appear in Physical Review DSubjects: gr-qc astro-ph.HE hep-th physics.plasm-phCreated: 2026-09-21; Updated: 2026-09-24; Datestamp: 2026-09-24
In a tetrad formulation of general relativity, an ideal Ohm-type condition for the gravitational field implies the conservation of gravitational fluxes and the preservation of the connectivity of gravitational field sheets. We investigate the consequences of departures from ideal gravitational evolution by developing a theory of gravitational RECONNECTion, defined as a change in the connectivity of gravitational field sheets arising from the breakdown of the ideal frozen-in evolution of the gravitational field. We derive quantitative measures of the gravitational RECONNECTion rate, show that gravitational RECONNECTion alters the energy-momentum exchange between the gravitational and matter sectors, and determine how it modifies the evolution of gravitational helicity. Our results provide a quantitative framework for describing changes in gravitational connectivity and their consequences in dynamical spacetimes.
[abstract 26 / 59] (score: 3) - Title: Radio Quasars in the Cosmic Dawn: A Spectroscopic Sample from the DESI SurveyAuthors: Anniek J. Gloudemans, Jinyi Yang, David M. Alexander, Arjun Dey, Xiaohui Fan, Victoria A. Fawcett, Martin J. Hardcastle, Stephanie Juneau, George K. Miley, Leah K. Morabito, Adam D. Myers, Swayamtrupta Panda, Huub J. A. Röttgering, Timothy Shimwell, Daniel J. B. Smith, Feige Wang, J. Aguilar, S. Ahlen, D. Bianchi, D. Brooks, T. Claybaugh, A. Cuceu, A. de la Macorra, P. Doel, S. Ferraro, J. E. Forero-Romero, E. Gaztañaga, S. Gontcho A Gontcho, G. Gutierrez, C. Hahn, M. Ishak, R. Joyce, R. Kehoe, D. Kirkby, T. Kisner, A. Kremin, M. Landriau, L. Le Guillou, M. E. Levi, M. Manera, A. Meisner, R. Miquel, J. Moustakas, S. Nadathur, W. J. Percival, F. Prada, I. Pérez-Ràfols, A. Robertson, G. Rossi, E. Sanchez, E. F. Schlafly, D. Schlegel, J. Silber, D. Sprayberry, G. Tarlé, B. A. Weaver, R. Zhou, H. Zou,Comments: Accepted for publication in the Astrophysical Journal. 19 pages, 13 figuresSubjects: astro-ph.GACreated: 2026-09-22; Updated: 2026-09-24; Datestamp: 2026-09-24
We present the largest statistical spectroscopic sample of radio QUASARs at 4.7
[abstract 27 / 59] (score: 3) - Title: The lifetimes and properties of Little Red Dots in the AMBRA simulationAuthors: Patrick LaChance, Yihao Zhou, Aklant Kumar Bhowmick, Rupert A. C. Croft, Tiziana Di Matteo, Laura Blecha, Fabio Pacucci, Paul Torrey, Simeon Bird,Comments: 19 pages, 11 figuresSubjects: astro-ph.GA astro-ph.COCreated: 2026-09-22; Updated: 2026-09-24; Datestamp: 2026-09-24
We identify and analyze the little red dots (LRDs) in the AMBRA cosmological hydrodynamic simulation, by producing mock observations of the galaxies and ACTIVE GALACTIC NUCLEi (AGN) between redshifts 5 and 8. We produce these mock observations with both a standard AGN emission model, and a ``gas-enshrouded'' model, and find that the presence of a gas-enshrouded AGN is instrumental to the reproduction of dim LRDs (F444W magnitude $>$ 26.0). We find a steeper decrease in LRD density between $z=5$ and $z=8$ within AMBRA than seen in observations, resulting in a relative underproduction of LRDs beyond $z\sim6$ in AMBRA. With the addition of unresolved AGN variability, the decline with redshift flattens, and the LRD redshift evolution in AMBRA becomes broadly consistent with other theoretical datasets, and closer to that seen in observations. We find that the LRDs in AMBRA are pre-existing BLACK HOLE--galaxy systems that are undergoing an LRD phase, selected primarily by the brightness of the AGN relative to its host. While the exact duration of these LRD phases is not possible to determine due to the unresolved nature of the AGN environment, we use the available time-series data to place limits on the lifetimes of the LRDs in AMBRA. We find that the vast majority of LRDs in AMBRA have lifetimes between $\sim3$ and $\sim 300$ Myr with LRD lifetime increasing with both BLACK HOLE and host galaxy mass. The lower mass LRDs are more dependent on housing a gas-enshrouded AGN, and have shorter lifetimes ($\rm \sim30~Myr$). The higher mass LRDs are less sensitive to their AGN environment, but require more compact host galaxies, and have longer lifetimes ($\rm \sim100~Myr$).
[abstract 28 / 59] (score: 3) - Title: Radio component of the multi-messenger emission from the anticipated T Coronae Borealis outburstAuthors: O. Petruk, T. Kuzyo, S. Orlando, L. Chomiuk, F. Bocchino, M. Miceli, V. Beshley,Comments: Submitted to Astronomy & Astrophysics. Comments are welcomeSubjects: astro-ph.HECreated: 2026-09-23; Updated: 2026-09-24; Datestamp: 2026-09-24
T Coronae Borealis is the nearest symbiotic recurrent nova and is expected to undergo a new eruption soon, offering a rare opportunity to study shock evolution and particle acceleration. We predict radio emission from the outburst and assess how radio observations can constrain the circumbinary medium (CBM) and cosmic-ray acceleration. We post-process three-dimensional (3D) hydrodynamic nova simulations with a multi-zone model for particle acceleration and radio emission, computing thermal free-free and non-thermal SYNCHROTRON radiation, including the Razin effect and free-free and SYNCHROTRON self-absorption for different CBM configurations. Early radio morphology should not be interpreted directly as the intrinsic shock geometry, because free-free absorption selectively obscures regions of the 3D emitting volume. The intrinsic radio emission is dominated by SYNCHROTRON radiation from electrons accelerated at the forward shock, with unabsorbed fluxes reaching 100-1000 Jy at GHz frequencies during the first day. Dense ejecta and shocked CBM material strongly absorb the emission, reducing the observable flux by several orders of magnitude. The source becomes largely transparent at GHz frequencies within about one month. Radio emission remains predominantly non-thermal during the first year, while thermal emission becomes important only for dense equatorial enhancements. The radio spectral index evolves from positive values caused by absorption to the optically thin SYNCHROTRON value of about 0.5 after several weeks. A short-lived polarized signal may arise during the first few days if the red giant's MAGNETic field contributes to the cosmic-ray-generated field. Early multi-frequency radio monitoring and polarimetry of the forthcoming T CrB eruption will probe density structure and MAGNETic field, testing particle acceleration in symbiotic recurrent novae.
[abstract 29 / 59] (score: 3) - Title: 4U 1624-490 as a possible intermediate-mass X-ray binary: constraints from XRISM and NUSTAR spectroscopyAuthors: R. Iaria, A. Anitra, T. Di Salvo, A. Sanna, F. Barra, L. Burderi, C. Maraventano, S. Caserta, W. Leone, C. Miceli,Comments: 17 pages, 9 figures, accepted for publication in A&A, Sect. 7: Stellar structure and evolutionSubjects: astro-ph.HECreated: 2026-09-23; Updated: 2026-09-24; Datestamp: 2026-09-24
High-inclination dipping neutron-star X-ray binaries provide a direct view of accretion-flow structure because the line of sight intercepts ionised plasma above the disc. We analyse two XRISM/Resolve observations of 4U 1624$-$490 with simultaneous NUSTAR coverage, dividing the data into seven orbital-phase intervals. Phase-resolved fits include neutral partial covering, a photoionised absorber, thermal Comptonisation, and ionised disc reflection. Fe XXV and Fe XXVI absorption are detected over most of the orbit. The absorber column density, ionisation state, covering fraction, and projected velocity vary with orbital phase and the lines are systematically blueshifted, with line-of-sight velocities of about $85$-$440\ {\rm km\,s^{-1}}$. Absorption-only models leave broad Fe-K residuals, while ionised reflection improves the fits. The velocity modulation has a semi-amplitude $K=210\pm14\ {\rm km\,s^{-1}}$ and, if interpreted as orbital motion, implies a mass function $f(M)=0.83\pm0.17\,M_\odot$. Residual structure in the blue wing of Fe XXVI suggests additional kinematic complexity near the dip, but the modulation remains consistent when the two dip-adjacent measurements are excluded. If the absorber traces the neutron-star orbital motion, the inferred donor mass is $M_2=2.66\pm0.32\,M_\odot$, compatible with a Roche-lobe-filling B9 V-B9.5 V star. Under this interpretation, 4U 1624$-$490 may be an intermediate-mass rather than a classical low-mass X-ray binary. (Abridged abstract)
[abstract 30 / 59] (score: 3) - Title: Investigating the ionization mechanisms powering the extreme emission lines in metal-poor galaxiesAuthors: C. Daoutis, V. Lebouteiller, D. Schaerer, I. Morel, O. Bait, S. Satyapal, S. Doan, B. Trahin, A. Gurpide, Y. Izotov, N. Guseva, L. Ramambason, A. Verhamme, SpeXion Team,Comments: Submitted for publicationSubjects: astro-ph.GACreated: 2026-09-23; Updated: 2026-09-24; Datestamp: 2026-09-24
Extreme emission metal-poor galaxies (EEMPGs) are excellent local laboratories for understanding the extreme physical conditions and ionizing radiation fields in the early Universe. However, the exact source of high-ionization emission lines in them, whether from intermediate-mass BLACK HOLEs (IMBHs), ultra-luminous X-ray sources (ULXs), or radiative shocks, remains debated. We characterize the fundamental properties and ionizing radiation field on metal-poor EEMPGs, aiming to identify the dominant sources of the highly ionizing photons that drive these lines. We selected a sample of 11 EEMPGs, among the most metal-poor galaxies with JWST/MIRI observations known so far (12+log(O/H) < 8.0, or Z/Z$_\odot$ < 20%). Using optical and IR diagnostic diagrams for ions of both high and low ionization potential, we constrain the ionization source dominating their spectral features. We detect high-ionization lines, notably He II$λ$4686 in all galaxies and [Ne V] 14.3 $μ$m in 42% of a broader sample of local EEMPGs. The multi-wavelength diagnostic diagrams reveal that our EEMPGs are located in areas that normally are occupied by ACTIVE GALACTIC NUCLEi (AGNs) or between the star-formation and AGN sequences. Evaluating the energetics required to produce these lines, we find that radiative shocks and ULXs are not sufficient. Instead, our analysis suggests that a combination of sources with star-formation and a small contribution from an IMBH provide enough high-energy photon budget to explain the emission lines of ions with high-ionization potentials (> 54 eV). Our EEMPG sample, covering various properties, is ideal for studying the first galaxies. Their flux ratios of low- and high-ionization lines suggest stellar radiation as the likely ionization source, with a small contribution from an IMBH (4-8%). Pure shocks fail to explain the observed emission line ratios and ionizing photon budget.
[abstract 31 / 59] (score: 3) - Title: A Search For Stellar-mass Black Holes Via Astrometric Microlensing II: 2012-2015 Keck CandidatesAuthors: Mace J. Huston, Jessica R. Lu, Casey Y. Lam, J. Nijaid Arredondo, Natasha S. Abrams, Shep Brooke, Sage H. Remulla, Eran Ofek, Michael S. Medford, Fatima Abdurrahman, Shrihan Agarwal, Edward Broadberry, Matthew Freeman, Matthew W. Hosek, Siyao Jia, Sean K. Terry, The OGLE Collaboration, :, Andrzej Udalski, Przemek Mroz, Radoslaw Poleski, Jan Skowron, Michal K. Szymanski, Igor Soszynski, Pawel Pietrukowicz, Szymon Kozlowski, Krzysztof Ulaczyk, Krzysztof A. Rybicki, Patryk Iwanek, Marcin Wrona, Mariusz Gromadzki, Mateusz J. Mroz, Michal Malkowski, The MOA Collaboration, :, Fumio Abe, David P. Bennett, Aparna Bhattacharya, Ian A. Bond, Kotaro Daimon, Ryusei Hamada, Yuki Hirao, Shuma Makida, Stela Ishitani Silva, Shota Miyazaki, Yasushi Muraki, Tutumi Nagai, Kansuke Nunota, Ryo Ogawa, Ryunosuke Oishi, Hideaki Ose, Greg Olmschenk, Clement Ranc, Nicholas J. Rattenbury, Yuki K. Satoh, Takahiro Sumi, Daisuke Suzuki, Takuto Tamaoki, Chihiro Ueda, Paul J. Tristram, Aikaterini Vandorou, Hibiki Yama,Comments: submitted to AAS Journals; 32 pages, 12 figuresSubjects: astro-ph.SR astro-ph.GACreated: 2026-09-23; Updated: 2026-09-24; Datestamp: 2026-09-24
The Milky Way is expected to host $\sim$10$^8$ stellar-mass BLACK HOLEs with an uncertain binary fraction. The only proven method to detect isolated stellar mass BLACK HOLEs is gravitational microlensing. Here we report the results of a microlensing search for BLACK HOLEs with photometry and astrometry. By combining 10 years of seeing-limited photometry from OGLE and MOA with diffraction-limited photometry and astrometry from adaptive optics imagers at the W.~M.~Keck Observatory, we constrain lens masses for OGLE-2012-BLG-0169, OGLE-2014-BLG-0613/MOA-2015-BLG-041, OGLE-2015-BLG-0029/MOA-2015-BLG-170, and OGLE-2015-BLG-0211. Of the four long-duration microlensing events monitored, we ruled out BLACK HOLE lenses in 3 events, which likely have stellar or white dwarf lenses. OGLE-2015-BLG-0211 remains a BLACK HOLE candidate with a poorly constrained lens mass with a 1$σ$ upper mass limit of 3.2$M_\odot$ and a 3$σ$ upper mass limit of 21.6$M_\odot$. This event suffered from poor observing conditions and significant astrometric reference frame uncertainties, but its analysis may benefit from additional astrometric data in the upcoming Gaia Data Release 4. Of the six long-timescale ($t_E>100$ days) microlensing events from this work and previous studies, one BLACK HOLE has been confirmed with a second not ruled out. We briefly examine Galactic model simulations and find that our result agrees with current expectations. Ultimately, we need a larger sample of isolated BLACK HOLEs to constrain their formation processes. This will be possible in the coming years with Rubin and Roman, as well as improved astrometry from JWST and large, ground-based telescopes equipped with adaptive optics.
[abstract 32 / 59] (score: 2) - Title: GLIMPSED: Direct evidence for a fast ACTIVE GALACTIC NUCLEus-driven outflow from a z=6.64 little red dot host galaxyAuthors: Damien Korber, Rui Marques-Chaves, Daniel Schaerer, Gabriel Brammer, Archana Aravindan, Arghyadeep Basu, Qinyue Fei, Emma Giovinazzo, Vasily Kokorev, Alberto Saldana-Lopez, Maxime Trebitsch, Hakim Atek, John Chisholm, Ryan Endsley, Seiji Fujimoto, Lukas Furtak, Richard Pan, Rohan P. Naidu,Comments: 17 pages, Accepted in A&ASubjects: astro-ph.GACreated: 2026-09-23; Updated: 2026-09-24; Datestamp: 2026-09-24
We report the discovery of GLIMPSED-329380, a z=6.64 galaxy behind Abell S1063, which shows signs of an extreme ionised outflow driven by an ACTIVE GALACTIC NUCLEus (AGN). The deep JWST/NIRSpec medium grating observations show spatially resolved structures of a host galaxy containing the very fast outflow and an AGN, which we analyse separately. The outflow, mainly traced by broad [O III]λ5008 and Hα emissions in the host, reaches a full-width-at-half-maximum velocity of ~5350km/s, velocities only observed in AGN-dominated systems. From the Balmer decrement, we observe that while the narrow emission lines show no dust attenuation, the outflowing gas is dusty. We use emission lines diagnostics to infer gas abundances within the host galaxy. The oxygen abundance is 12+log(O/H)~7.96 (~18% solar) and the host is slightly nitrogen-enriched with log(N/O) ~ -0.68. Unless the extreme outflow turns out to be very dusty, the mass loading factor (>5-10%), and the kinetic energy (>1e43erg/s) of the extreme outflow does not hint at a significant impact on the galaxy. The AGN component shows many similarities with little red dots (LRDs): a characteristic 'V shape', exponential profile in hydrogen lines, numerous detection of forbidden [Fe II] lines, a Balmer break, and a broad absorption feature at ~4550Å. This detection of a fast outflow in an LRD, rare in surveys dominated by low-resolution (e.g. PRISM) spectra, provides direct evidence of AGN activity in these systems.
[abstract 33 / 59] (score: 2) - Title: Red noise and evolving signals: a complete frequentist approach to supermassive BLACK HOLE binary searches with pulsar timing arraysAuthors: Xuan Tao, Boris Goncharov, Yiqian Qian, Yan Wang, Soumya D. Mohanty,Comments: 20 pages, 12 figures. Revised and expanded version, including empirical ROC comparisons. Data and code: https://doi.org/10.5281/zenodo.22728075Subjects: gr-qc astro-ph.CO astro-ph.HE astro-ph.IMCreated: 2026-09-23; Updated: 2026-09-24; Datestamp: 2026-09-24
Searches for gravitational waves (GWs) from isolated supermassive BLACK HOLE binaries (SMBHBs) in pulsar timing array (PTA) data require simultaneous estimation of signal and noise parameters, so the dimensionality of the fit scales with the number of observed pulsars. This computational difficulty is exacerbated when source evolution from GW emission is included, since retaining both Earth and pulsar terms introduces the unknown pulsar distances. Existing frequentist methods such as the $\mathcal{F}$-statistic are restricted to non-evolving sources. In addition, they often rely on a noise covariance estimated from the same data and then held fixed during the signal search, which can bias parameter estimates. We present a Generalized Likelihood Ratio Test and the associated $\mathcal{T}$-statistic that overcomes the aforementioned limitations. This formulation extends earlier work in which the dimensionality of the fitting problem was drastically reduced by semi-analytical maximization of the likelihood over the pulsar phase parameters, followed by efficient global optimization over the remaining parameters using Particle Swarm Optimization. Our simulations demonstrate that for an evolving SMBHB signal with chirp mass $\mathcal{M}=10^{9.2} M_\odot$ and signal-to-noise ratio $20$, this detection statistic achieves a $100\%$ detection probability at a false-alarm probability of $0.06$ in a 30-pulsar timing array, which is characterized by a $100 \mathrm{ns}$ root-mean-square white noise residual and pulsar-specific red noise. For the 30-pulsar timing array at signal-to-noise ratio $10$ and false-alarm probability $0.06$, $\mathcal{T}$ detects $99/100$ realizations, outperforming the $\mathcal{F}_p$ statistic evaluated with the $H_0$-fitted covariance, which detects $71/100$ realizations.
[abstract 34 / 59] (score: 2) - Title: Experimental validation of a fast control-oriented, physics-informed surrogate model for plasma equilibrium reconstruction in the TCV tokamakAuthors: M. Grandin, A. Mele, C. Galperti, D. Gonzales Castineiras, C. Heiß, A. Cenedese, TCV team, EUROfusion Tokamak Exploitation team,Comments: Code available at https://github.com/matgrand/liuqe-nn Accepted for presentation at the 65th IEEE Conference on Decision and Control (CDC 2026)Subjects: physics.plasm-phCreated: 2026-09-23; Updated: 2026-09-24; Datestamp: 2026-09-24
Magnetic equilibrium reconstruction provides the plasma state estimate required for real-time shape control in tokamaks. We present a fast, physics-informed neural network surrogate of the \texttt{liuqe} equilibrium reconstruction code \cite{liuqe1} for the TCV tokamak at EPFL, achieving inference times below 100~$\bmμ$s and enabling 10~kHz shape control. The model is trained on around 10,000 TCV discharges spanning the full operational range of plasma shapes. Its modular branch/trunk architecture decouples MAGNETic measurement encoding from spatial coordinate processing, enabling physics-informed regularization via automatic differentiation of the predicted flux map. The surrogate has been compiled and deployed on the TCV real-time control system, and validated both offline and in real time against the models \texttt{liuqe-rt} and \texttt{lih}, showing comparable accuracy. Closed-loop performance assessed with the real-time software in-the-loop \texttt{fge} \cite{fge1} demonstrates control-equivalent behavior across multiple control strategies.
[abstract 35 / 59] (score: 2) - Title: MusE GAs FLOw and Wind (MEGAFLOW) XIV: Background-Galaxy Absorption Reveals Kiloparsec-Scale Structure in the Cool Circumgalactic MediumAuthors: Yucheng Guo, Nicolas F. Bouché, Martin Wendt, Timothy Heckman, Joop Schaye, Sanchayeeta Borthakur, Johannes Zabl, Maxime Cherrey, Sowgat Muzahid, Ismael Pessa, Ramona Augustin, Daria Kozlova,Comments: Submitted to A&ASubjects: astro-ph.GACreated: 2026-09-23; Updated: 2026-09-24; Datestamp: 2026-09-24
The properties of the cool ($T\sim10^4$~K) gas in the circumgalactic medium (CGM) are closely linked to the physical mechanisms that create and maintain this multiphase medium. The cool CGM is thought to consist of discrete clouds, whose characteristic size is unknown. Here we present a geometric and direct approach to constrain the coherence scale of these cool structures using stacked MgII absorption lines measured against extended background galaxies and effectively point-like background QUASARs, whose sizes are a few kpc and $\lesssim 0.01$pc, respectively. When the background-source size is smaller than the coherence scale of the foreground clouds, incomplete covering lowers the detection fraction and causes the median stacked absorption to differ from the mean. For stacked MgII absorption against background galaxies, the mean and median equivalent width (EW) profiles are broadly consistent. For stacked MgII absorption against background QUASARs, by contrast, the median and mean EW profiles differ significantly, reaching a $\approx10σ$ difference beyond 100 kpc. Furthermore, we find that the median and mean EW profiles are broadly consistent for large background galaxies (median half-light radius $\approx 6.6$ kpc), but differ at the $\approx3σ$ level for small background galaxies ($\approx 1.5$ kpc). This suggests that the MgII-bearing gas has an effective transverse coherence scale of order a few kiloparsecs, broadly consistent with the $\sim$2--7 kpc range probed by the background galaxies. Using a toy model in which the CGM is populated with discrete cool clouds, we show that the observed differences arise naturally from the combination of partial covering and beam averaging. Our results provide a new geometry-based measure of the small-scale structure of cool CGM gas.
[abstract 36 / 59] (score: 2) - Title: Short Spike, Long Story: Episode-Dependent Shifts of Long-Duration Type-I GRBs on $E_{\rm p,z}$--$E_{\rm iso}$ PlaneAuthors: Ya-Hui Jiang, Run-Chao Chen, Zhen-Yu Yan, Kamil Nadaf, Xiao-Hong Zhao, Bin-Bin Zhang,Comments: 14 pages, 5 figures, 2 tablesSubjects: astro-ph.HECreated: 2026-09-23; Updated: 2026-09-24; Datestamp: 2026-09-24
Observations of peculiar GRBs have challenged the traditional $T_{90}$-based classification, demonstrating that duration does not map uniquely onto progenitor type. A striking class is long-duration Type~I GRBs -- merger-origin events whose prompt emission lasts far longer than the canonical 2 s boundary, typically comprising an initial short hard spike followed by softer extended emission. Identifying the physical origin of such bursts requires diagnostics beyond duration alone, among which the Amati relation, linking rest-frame spectral peak energy $E_{\rm p,z}$ and isotropic-equivalent energy $E_{\rm iso}$, is widely used as a complementary classification tool. We analyze a sample of eight long-duration Type~I GRBs and merger candidates by separating the initial spike from the extended emission and examining their episode-dependent locations on the $E_{\rm p,z}$--$E_{\rm iso}$ plane. We find that the initial spike generally lies within, or close to, the empirical Type~I region, consistent with a compact-merger-like prompt-emission component. In contrast, the extended-emission episode systematically occupies a region closer to Type~II GRBs, and could be misidentified as collapsar-like if analyzed in isolation. This episode-dependent Type~I-to-Type~II transition is further supported by time-resolved spectral analysis, although its magnitude and trajectory vary among bursts, suggesting diversity in central-engine evolution or outflow properties between the two phases. Our results caution that the Amati relation alone can lead to misleading empirical classification when the initial hard spike is weak, outside the instrumental bandpass, or missed entirely, leaving only the extended emission to be analyzed. Broad temporal and spectral coverage, and independent multi-wavelength diagnostics, is therefore essential for identifying the physical origin of these events.
[abstract 37 / 59] (score: 2) - Title: Muon decay across scales: from LEFT to SMEFTAuthors: Carl Jakob Moritz, Tyler Corbett,Comments: 31 pages plus appendices, 3 figures, 4 tablesSubjects: hep-phCreated: 2026-09-23; Updated: 2026-09-24; Datestamp: 2026-09-24
We revisit precision muon decay in the framework of the LEFT by considering how the LEFT perturbs the total rate as well as the standard and POLARIZATION-dependent Michel parameters. We derive the dependence of these observables on the dimension-five and -six LEFT operators, including lepton number violating operators, allowing for arbitrary neutrino flavor assignments. We consider fits of the LEFT to the muon decay data, in particular an approach to neutrino flavor general fits that does not respect the LEFT power counting and assuming new physics couples to all flavors equally and therefore allows for a consistent fit. We then consider how new physics imprints on the SMEFT and subsequently the LEFT in order to constrain specific scenarios of single-field extensions as well as two motivated two-field extensions. While we infer associated mass scales for these scenarios in the hundreds of GeV to multi-TeV range we also find that for the specific cases of lepton number violation, neutrino mass constraints from operator mixing are more restrictive than muon decay.
[abstract 38 / 59] (score: 2) - Title: Frozen-In Gravitational FieldsAuthors: Felipe A. Asenjo, Maricarmen A. Winkler, Luca Comisso,Comments: Published in Physical Review LettersSubjects: gr-qc astro-ph.HE hep-th physics.plasm-phCreated: 2026-09-21; Updated: 2026-09-24; Datestamp: 2026-09-24
Spacetime can undergo complex nonlinear evolution, as governed by the Einstein field equations, and a central challenge is to understand the geometric structures that arise, persist, and interact throughout its evolution. Using a formulation of Einstein equations that parallels nonlinear electrodynamics of continuous media, we show that general relativity admits gravitational field connections---two-surfaces and associated field lines whose connectivity is maintained by the spacetime dynamics. This gravitational frozen-in behavior is enabled by an ideal Ohm-type condition for the gravitational field. We further show that the same framework naturally leads to a conserved ``gravitational MAGNETic'' flux. A conserved gravitational helicity also emerges, with a clear topological interpretation in terms of gravitational field-line structures. These results identify well-defined topological constraints on admissible spacetime evolution and provide an organizing principle underlying the nonlinear dynamics of spacetime.
[abstract 39 / 59] (score: 2) - Title: Probing MAGNETic correlations in anisotropic turbulenceAuthors: Bijita Bose, Somdeep Dey, Soma Sanyal,Comments: 16 pages 12 figuresSubjects: physics.flu-dyn astro-ph.COCreated: 2026-09-21; Updated: 2026-09-24; Datestamp: 2026-09-24
The topological classes of coherent structures in MAGNETohydrodynamic turbulence are studied using the irreducible representations of the SO(3) and SO(2) rotation groups. We probe the coherent structures around axisymmetric MAGNETic fields in the universe. Such axisymmetric fields can be found around filamentary structures as well as cosmic strings. We have considered a Gaussian and a non Gaussian MAGNETic field. We find that the field distribution leads to different coherent structures for the two cases. Our results show that the scattering of particles from the Gaussian structure depends predominantly on two lengthscales. In the case of the non Gaussian distribution, we can define a third intermediate lengthscale, similar to the Taylor lengthscale. In both the cases, we find that there is a dominance of the POLARIZATION anisotropy which indicates that the field gradients are forced into rigid spatial configurations. In the early universe, this will change the mean free path of the baryons and leptons in the coherent structures. Trapping of charged particle as well as their acceleration will be more frequent in the case of a MAGNETic field with a heavy tailed distribution. The lengthscale of density inhomogeneities close to these structures will thus be determined by the MAGNETic field distribution of the fields.
[abstract 40 / 59] (score: 2) - Title: Twin Universes and Bimetric Gravity: From Sakharov's Cosmological Symmetry to Modern Speculations on Negative MassAuthors: Jean-Pierre Luminet,Comments: 14 pagesSubjects: physics.gen-ph gr-qcCreated: 2026-09-21; Updated: 2026-09-24; Datestamp: 2026-09-24
We review the conceptual and theoretical status of twin-universe models, from Sakharov's early ideas on baryogenesis, CPT symmetry, and reversed arrows of time to recent quantum-cosmological scenarios involving pair-created entangled universes. Particular attention is given to the distinction between Sakharov-type cosmological symmetry, modern bimetric theories of gravity, and speculative models involving negative mass sectors. We summarize the main consistency conditions faced by bimetric gravity, including the Boulware-Deser ghost, Higuchi-type bounds, covariant conservation laws, and no-go results for positive- and negative-mass sectors. We then examine the Janus cosmological model and related black-hole replacement proposals, emphasizing the difference between heuristic twin-universe narratives and fully specified RELATIVISTIC field theories. We argue that while twin-universe ideas remain a fertile framework for questions about the arrow of time, matter-antimatter asymmetry, and the quantum origin of the universe, models combining bimetric gravity, negative mass, dark-sector phenomenology, and alternatives to Kerr BLACK HOLEs face a substantial burden of mathematical and observational proof.
[abstract 41 / 59] (score: 2) - Title: Compact Object Mergers and Micro-Tidal Disruption Events: A Multi-Messenger Probe of Dense Stellar EnvironmentsAuthors: Konstantinos Kritos, Francesco Iacovelli, Rosalba Perna, Emanuele Berti,Comments: 35 pages, 22 figuresSubjects: astro-ph.HE astro-ph.GA gr-qcCreated: 2026-09-22; Updated: 2026-09-24; Datestamp: 2026-09-24
Dense stellar environments such as globular clusters and young massive clusters produce both compact-object mergers detectable in gravitational waves and tidal disruption events observable electroMAGNETically. We investigate compact-object mergers, tidal disruption events, and micro-tidal disruption events ($μ$TDEs) in these environments using rapid Monte Carlo star-cluster simulations with the Rapster code, extended with a unified treatment of neutron-star (NS) and black-hole (BH) spin evolution under disk accretion across the NS-to-BH transition, as well as new dynamical channels for disruptions by single compact objects and by BH-BH binaries. Simulating $10^5$ clusters across ten model variations and two formation histories, we find a BH-BH merger-rate density peaking at $z\approx2$-$3$ at several tens ${\rm Gpc}^{-3}\,{\rm yr}^{-1}$, consistent with the local LVK rate, while the cumulative number of $μ$TDEs exceeds that of mergers by a factor of a few. Since we include only dynamically formed binaries, $\approx90\%$ of $μ$TDEs proceed through single compact-object-star encounters, and our rates are conservative lower limits. Prograde accretion during $μ$TDEs spins up compact objects, providing a purely dynamical, randomly oriented pathway for producing high-spin BHs, and can drive accretion-induced collapse of NSs to BHs that populate the lower mass gap.
[abstract 42 / 59] (score: 2) - Title: Light-curve analysis of the classical nova YZ Ret: revisit with fully self-consistent nova outburst modelsAuthors: Izumi Hachisu, Mariko Kato,Comments: 10 pages, 4 figures, accepted for publication in ApJSubjects: astro-ph.SR astro-ph.HECreated: 2026-09-22; Updated: 2026-09-24; Datestamp: 2026-09-24
YZ Ret is a well observed nova from the first detection of an X-ray flash phase in classical novae until the end of a supersoft X-ray source phase. We have reanalyzed multiwavelength light curves of YZ Ret over the total duration of the outburst. Our fully self-consistent nova outburst model, a 1.25 $M_\odot$ white dwarf (WD) and a mass accretion rate of $1\times 10^{-9} ~M_\odot$ yr$^{-1}$ on to the WD, reasonably reproduced $V$/$g$ light curves as well as the very early X-ray flash and late supersoft X-ray light curves. This model explains the emergence epoch of the GeV gamma-ray emission because a shock naturally arises far outside the nova (WD) photosphere just after the optical maximum. In our model, before optical maximum, later ejected matter has a smaller velocity than that of earlier ejecta and therefore the ejecta expands while, after optical maximum, later ejected matter has a larger velocity than that of earlier ejecta and collision with the earlier ejecta makes a shock.
[abstract 43 / 59] (score: 2) - Title: Effects of the Internal Transport Barrier in the plasma confinement with Resonant Magnetic PerturbationsAuthors: P. Haerter, L. C. Souza, R. L. Viana, I. L. Caldas,Comments:Subjects: physics.plasm-ph nlin.CDCreated: 2026-09-22; Updated: 2026-09-24; Datestamp: 2026-09-24
In the pursuit of steady-state fusion energy, Advanced Tokamak regimes rely on Internal Transport Barriers (ITBs) with reversed MAGNETic shear. While Resonant Magnetic Perturbations (RMPs) are commonly applied to control Edge Localized Modes (ELMs) by intentionally making the plasma edge chaotic, the RMPs can also affect the reversed-shear cores. To address this compatibility, we propose a new, adjustable analytical model for plasma current that explicitly incorporates the core, ITB, and edge pedestal components. By applying this current formulation to a Hamiltonian map, we compare how easily MAGNETic chaos reaches the core in ITB-driven reversed-shear (Non-Twist) plasmas. We find that the localized ITB current creates "twin" inner resonances and pushes outer MAGNETic island chains closer to the edge. These results highlight a critical operational trade-off: while the Non-Twist topology makes ELM control easier at lower coil currents, it severely shrinks the safety margin against a complete, RMP-induced loss of global confinement.
[abstract 44 / 59] (score: 2) - Title: A multi-telescope fit to the FRB population, allowing for FRB repetitionAuthors: Jordan L. Hoffmann, Clancy W. James, Jason X. Prochaska, Ines Pastor-Marazuela, Kritti Sharma, Liam Connor,Comments: 17 pages, 9 figures, 7 tables, submitted to PASASubjects: astro-ph.HE astro-ph.COCreated: 2026-09-23; Updated: 2026-09-24; Datestamp: 2026-09-24
Fast radio bursts (FRBs) are millisecond-duration radio pulses with extragalactic origins. A majority of FRBs have only had a single pulse detected from them; however, an increasing number have been identified as repeaters. Here we present a full redshift -- dispersion measure ($z$-DM) analysis including a simple power-law model of repetition rates. We assume all FRBs are drawn from the same intrinsic population and fit these FRB population parameters using data from ASKAP, Murriyang (Parkes), DSA, FAST, MeerKAT and CHIME catalogue 1. We do not utilise data from CHIME catalogue 2 yet, as we cannot robustly identify all repeaters in the sample. We constrain the minimum repetition rate above $10^{39}$ erg to $R_{\mathrm{min}}=-4.23^{+1.10}_{-1.74}$ d$^{-1}$, the maximum repetition rate to $R_{\mathrm{max}} \gtrsim 1$ d$^{-1}$ and the repetition rate index to $R_γ=-2.20^{+0.12}_{-0.22}$. These parameters do not show significant correlation with any other FRB parameters. Our values are an improvement on existing results and are self-consistent with the DM distribution of CHIME and observed ratios of repeaters to non-repeaters across the sky. We also provide updated estimates of the FRB energy function and host galaxy parameters.
[abstract 45 / 59] (score: 2) - Title: Quasinormal-mode redshifts of BLACK HOLEs in galactic halos with radial pressuresAuthors: Che-Yu Chen, Hassan Hassanabadi, Soroush Zare,Comments: 10 pages, 1 figureSubjects: gr-qc astro-ph.CO astro-ph.GA astro-ph.HECreated: 2026-09-23; Updated: 2026-09-24; Datestamp: 2026-09-24
We investigate the black-hole quasinormal mode redshifts induced by a galactic dark-matter halo with nonvanishing radial pressure. The halo is described by an anisotropic fluid with a generalized density profile and a constant radial equation-of-state parameter $w$. We construct the corresponding static, spherically symmetric spacetime and study the resulting corrections to the unstable light ring and quasinormal-mode spectrum. For dilute halos and $w\neq -1$, the light-ring angular frequency and Lyapunov exponent acquire the same leading-order gravitational redshift, implying a universal shift of the real and imaginary parts of the quasinormal frequencies. The magnitude of this effect depends on both the halo structure and the radial pressure. This universal redshift relation holds not only in the case of $w=0$ that has been discovered in the literature but also in a much wider scenario, supporting its importance in BLACK HOLE spectroscopy. On the other hand, the case $w=-1$ is qualitatively different: the factor that corresponds to the leading common redshift vanishes, the corrections are further suppressed by the hierarchy between the black-hole and halo scales, and the universal relation is broken, with the dominant contribution controlled by the inner halo profile. Our numerical computations of scalar-field quasinormal mode spectra confirm the analytic eikonal results.
[abstract 46 / 59] (score: 2) - Title: On the rates of binary star collisions around hypermassive BLACK HOLEsAuthors: Megha Sharma, Alexander Heger, Evgeni Grishin, Daniel J. Price,Comments: 14 pages, 14 figuresSubjects: astro-ph.HE astro-ph.GACreated: 2026-09-23; Updated: 2026-09-24; Datestamp: 2026-09-24
Observations of the Milky Way show that galaxies have binary stars in their centres. Using Monte Carlo simulations, we model the population statistics of encounters of such binaries with galactic central BLACK HOLEs (BHs) of mass 10^5-10^{10} Msun (hypermassive BHs >= 10^8 Msun HMBHs). Whereas main-sequence single stars cannot undergo tidal disruption events around HMBHs, stellar collisions of main-sequence binary stars may produce observable transients. We use the post-Newtonian Einstein-Infeld-Hoffmann (EIH) equations as implemented in the three-body code Multistar. We simulate 100,000 models each for six BH masses and 10 different binary parameter distributions. We find that stellar collisions occur in all models, with collision fractions ranging from ~7% for circular, equal-mass binaries to ~0.2% for the observationally motivated Moe2017 binary distribution. Most collisions occur for prograde, tight binaries at low impact parameters beta = r_t/r_p, where the tidal force of the BH drives up the binary eccentricity during pericentre passage. Collision velocities are close to the binary escape velocity for lower-mass BHs (<= 10^8 Msun), but span a wider range for higher-mass BHs, implying an increasing fraction of stellar mergers. Using empirical loss-cone rates and the local BH mass function, we estimate detectable LSST collision rates of ~8,600 and ~3,000 events per year for our Kroupa mass function, Opik's law, inclined orbit model and our MS17 model, respectively, around 10^6 Msun BHs; ~330 and ~150 events per year around 10^8 Msun BHs; and ~3.5 and ~2.8 events per year around 10^9 Msun BHs. These results suggest that binary stellar collisions around HMBHs represent a potentially observable population of nuclear transients that may contribute to the growing sample of ambiguous nuclear transients detected by wide-field optical surveys.
[abstract 47 / 59] (score: 2) - Title: Origin of the high-energy spectral cutoff in gamma-ray pulsar halosAuthors: Qi-Ling Chen, Ming-Ming Kang, Kun Fang, Hong-Bo Hu, Yi-Qing Guo, Chao-Wen Yang,Comments:Subjects: astro-ph.HECreated: 2026-09-23; Updated: 2026-09-24; Datestamp: 2026-09-24
The spectra of gamma-ray pulsar halos exhibit a clear cutoff feature at tens of TeV. This work investigates the origin of the spectral cutoff by interpreting the HAWC data of the Geminga halo. The most straightforward interpretation is that the cutoff reflects the maximum electron acceleration capability of the central PWN. We model this scenario using spherically symmetric diffusive shock acceleration, where the upstream scale of the PWN termination shock limits the maximum energy. We also propose an alternative interpretation of the cutoff: if the electron diffusion coefficient in the surrounding interstellar medium rises rapidly at high energies, a substantial fraction of high-energy gamma-ray flux from the target source can leak outside the analysis region, producing an observed spectral cutoff effect. Both explanations successfully reproduce the spectral cutoff of the Geminga halo. Meanwhile, the two scenarios make distinct predictions on the statistical properties of pulsar halo spectral cutoffs and the X-ray spectral features of the corresponding PWNe, which may be tested through further observations.
[abstract 48 / 59] (score: 2) - Title: H_alpha observations of the Be/X-ray binary MWC 656Authors: R. Zamanov, V. Marchev, K. A. Stoyanov, M. D. Christova, M. Minev, M. Moyseev, D. Marchev, J. Marti, M. F. Bode, P. Markishki, S. Stefanov,Comments: Astronomy & Astrophysics, acceptedSubjects: astro-ph.SR astro-ph.HECreated: 2026-09-23; Updated: 2026-09-24; Datestamp: 2026-09-24
Context. MWC 656 is a Be/X-ray binary identified as an emission-line object, X-ray and radio source and might be a weak gamma-ray source, harbouring an enigmatic secondary component. Aims. Our aim here is to study the orbital modulation of the H-alpha emission line, disc truncation and to evaluate the binary parameters. Methods. During the period 2021-2026, we obtained high resolution (30000) optical spectra of MWC 656 and analysed them together with the published data. Results. We find an orbital modulation of the H_alpha emission line with period P orb = 60.43 +/- 0.03 d. By assuming that the Be circumstellar disc is truncated by the companion, we estimate orbital eccentricity e = 0.11 +/- 0.01, semimajor axis a=160 R_sun, and mass of the binary M_1 + M_2 = 15.1 M_sun. Conclusions. The orbital modulation of the H_alpha emission suggests that (1) in this object we have a new type of cyclic variability of a Be disc; (2) the orbit is mildly eccentric; and (3) the secondary component of MWC 656 is a massive object 5 M_sun, more massive than the neutron stars - a stellar-mass BLACK HOLE or a massive stripped star.
[abstract 49 / 59] (score: 2) - Title: A fully implicit electroMAGNETic energy- and charge-conserving PIC model for simulations of high-$β$ plasmaAuthors: V. A. Kurshakov, I. V. Timofeev,Comments:Subjects: physics.plasm-phCreated: 2026-09-23; Updated: 2026-09-24; Datestamp: 2026-09-24
The paper presents a 3D numerical model of plasma in which a fully implicit PIC method with exact conservation of global energy and local charge is generalized to the electroMAGNETic case. This opens the possibility of simulating plasma equilibria with a high (up to an extreme) ratio of plasma pressure to MAGNETic field pressure, which are formed in open MAGNETic traps. The main goal of this work is to find out whether a fully implicit model, which usually performs numerous nonlinear iterations when solving the coupled Vlasov--Maxwell system, can compete in performance with semi-implicit models that achieve the same conservative properties at the cost of only a single particle push per time step. It turns out that in 3D geometry such competition is quite possible due to the growing computational cost of evaluating the mass matrices in the semi-implicit approach. The software implementation of the proposed numerical model is written in C++ within the parallel \texttt{xpic} code. Testing the code on problems of the development of the Weibel instability and the formation of plasma with extreme pressure showed good agreement between the semi-implicit and fully implicit approaches and made it possible to establish their relative speed.
[abstract 50 / 59] (score: 2) - Title: Broad-band spectral-timing: simultaneous NICER and HXMT observations reveal an anticorrelation between the softest and hardest X-ray fluxes in MAXI J1820+070Authors: Niek Bollemeijer, Phil Uttley, Bei You,Comments: 14 pages, 6 figures, accepted for publication in MNRASSubjects: astro-ph.HECreated: 2026-09-23; Updated: 2026-09-24; Datestamp: 2026-09-24
Black hole X-ray binaries (BHXRBs) in the hard state show variable X-ray emission across a wide range of energies. Hard X-rays are thought to be produced through Compton-upscattering of seed photons from the accretion disc by the hot X-ray corona, leading to a spectral component roughly shaped like a power-law with a high-energy cut-off. A complete study of the coronal variability requires a full view of the spectrum, from the low-energy cut-off at the seed photon energy to the high energy cut-off, which may be related to the coronal temperature. We present a detailed spectral-timing study of strictly simultaneous observations by NICER and Insight-HXMT of the bright BHXRB MAXI~J1820+070, covering the 0.3-250 keV energy range. The high data quality allows us to study the lags and coherence across the full X-ray band. We find that at low Fourier frequencies ($\lesssim0.02$ Hz), the soft X-ray flux below 1 keV and hard X-ray flux above 100 keV are anticorrelated, i.e. phase lags of $|π|$ rad. No anticorrelation is observed when comparing energy bands above 1 keV. We consider several explanations for the observed complex behaviour, such as a modulation of the coronal cut-off energy by the disc, power-law pivoting and a contribution from non-thermal electrons. Future, more detailed modelling efforts based on the observed effects may place new constraints on the dynamics of the X-ray emitting regions around accreting BLACK HOLEs.
[abstract 51 / 59] (score: 2) - Title: Semi-Analytic Solutions For Warped, Super-Eddington Accretion Disks with OutflowsAuthors: Gabriel Wohlfarth, Matthew Middleton, Omer Blaes, P. Chris Fragile,Comments:Subjects: astro-ph.HECreated: 2026-09-23; Updated: 2026-09-24; Datestamp: 2026-09-24
The discovery of billion solar mass BLACK HOLEs at high redshift challenges any standard Eddington-limited growth model. Previous work has shown that an advective accretion disk can account for these early BLACK HOLEs with episodic accretion. It has also been shown that if the accretion disk of a BLACK HOLE is misaligned from the spin axis of the BLACK HOLE, the disk can become advective within a certain radius. While warped and misaligned accretion disks have been explored in numerical simulations, there is no fully or semi-analytic framework that self-consistently connects disk warp, mass inflow, winds, and energy transport in the super-Eddington regime. In this work, we develop a first-principles semi-analytic model of a radiation-pressure-dominated, warped accretion disk, starting from the coupled conservation equations for mass, energy, and angular momentum. We find profiles for the radial velocity and surface density that explicitly account for disk warping and mass loss and determine the radius at which the disk becomes advective. We explore changes with BLACK HOLE spin, misalignment angle and viscosity, reproducing relevant results from numerical studies.
[abstract 52 / 59] (score: 2) - Title: A Diagnostic Method for Proto-Neutron Star Magnetic Fields by Supernova Fallback NeutrinosAuthors: Akihiro Inoue, Yudai Suwa, Ryuichiro Akaho, Shinsuke Takasao, Kazumi Kashiyama, Hiroyuki R. Takahashi,Comments: 24 pages, 10 figures, submitted to ApJSubjects: astro-ph.HECreated: 2026-09-23; Updated: 2026-09-24; Datestamp: 2026-09-24
Young isolated neutron stars exhibit a wide range of MAGNETic field strengths. To understand the origin of this diversity, it is important to observationally constrain MAGNETic fields during the proto-neutron star (PNS) phase. We propose a novel diagnostic of PNS MAGNETic fields using neutrinos associated with SUPERNOVA fallback. By performing one-dimensional general-RELATIVISTIC MAGNETohydrodynamic simulations of the SUPERNOVA fallback onto a MAGNETized PNS, we investigate how the energy spectra of the fallback neutrinos depend on the PNS MAGNETic field strength and the fallback accretion rate. We find that stronger MAGNETic fields and lower accretion rates produce softer spectra because the fallback neutrinos are emitted mainly near the MAGNETospheric radius, which becomes larger under these conditions. To quantify this spectral softening, we define a hardness ratio based on event rates above and below 30 MeV and introduce a hardness-event-rate diagram. Using this diagram, we identify the parameter region in which our diagnostic is applicable. Its applicability depends on the PNS MAGNETic field strength, fallback accretion rate, onset time of the fallback phase, and neutrino mass ordering. We also investigate the dependence on the PNS radius and find that a larger radius produces softer spectra, indicating a degeneracy between the MAGNETic field and PNS compactness. An independent constraint on the PNS compactness would therefore enable us to better constrain the MAGNETic field. These results suggest that future multimessenger observations of galactic SUPERNOVAe can provide a new window into the NS diversity.
[abstract 53 / 59] (score: 2) - Title: Detection of metal absorption lines in QUASAR spectra: a neural network approach using U-NetAuthors: Elena Sofia Mangola, Francesco Pistis, Michele Fumagalli, Matteo Fossati, Ting-Yun Cheng, Ryan J. Cooke, Rajeshwari Dutta, Ignasi Pérez-Ràfols, Matthew Pieri, Emanuel Gafton,Comments: 13 pages, 9 figures. Accepted in A&ASubjects: astro-ph.GACreated: 2026-09-23; Updated: 2026-09-24; Datestamp: 2026-09-24
Current and future large spectroscopic surveys are significantly enhancing the volume and resolution of QUASAR spectra that are observed, which requires the creation of efficient and precise automated techniques to detect absorption features. This study focuses on the detection of metal absorption features using a novel U-Net model on WEAVE-like mock spectra in the QUASAR rest-frame wavelength interval $1230\,\mathring{\mathrm{A}} \leq λ_{\rm RF} \leq 3095\,\mathring{\mathrm{A}}$. We test the network performance for absorption detection both on ideal data and after simulating the continuum fitting step as applied on real data. The performance of these architectures is evaluated by the completeness, purity, and F1 score reached in bins of signal-to-noise ($\mathrm{S}/ \mathrm{N}_\mathrm{line} $) for the absorption lines and with the absolute fractional flux error for the continuum. The ability to recover the correct line centers is also studied. The U-Net reaches scores of $\approx 90\%$ for all metrics (completeness, purity, and F1 score) at $\mathrm{S}/ \mathrm{N}_\mathrm{line} \approx 4$. All false positive detections with $\mathrm{S}/ \mathrm{N}_\mathrm{line} \geq 5$ fall in the tails of the broad Ly$α$ absorbers distribution of damped Ly$α$ systems. The combination of continuum fitting and line detections has negligible effects on the detection performance at $\mathrm{S}/ \mathrm{N}_\mathrm{line} \geq 4$. Our proposed U-Net architecture offers a competitive tool for the analysis of absorption lines in current and upcoming large spectroscopic surveys and is well-suited to the identification of any absorption line feature.
[abstract 54 / 59] (score: 2) - Title: Shock-free super-Eddington accretion onto MAGNETized neutron starAuthors: Galina Lipunova, Pavel Abolmasov,Comments: 11 pages, 5 figures, submitted to A&ASubjects: astro-ph.HECreated: 2026-09-23; Updated: 2026-09-24; Datestamp: 2026-09-24
Strong MAGNETic fields allow accreting neutron stars to form MAGNETically controlled funnel flows. At sufficiently high accretion rates, such flows become radiation-pressure-supported. In the conventional picture, the MAGNETospheric flow contains a nearly free-falling transonic outer region, a radiation-mediated shock, and a subsonic accretion column. We investigate the regime in which the height of the column is expected to exceed the MAGNETospheric radius. In this case a self-consistent transonic solution with a standing shock is no longer possible, and the entire MAGNETospheric flow remains subsonic. We construct a semi-analytical hydrodynamical solution for a fully subsonic, radiation-supported MAGNETospheric flow in the low-Mach-number limit. The MAGNETic field is treated in the force-free approximation, while the flow structure is determined by mass conservation, energy conservation, and the momentum equation along the field lines. We test the solution using one-dimensional time-dependent simulations with the code HACol. The shock-free solution is highly advective. Its enthalpy profile is close to the adiabatic limit, while the energy density is regulated by leakage of mass and heat through the sides of the accretion channel. Most of the observable power is expected to be released by plasma leaving the MAGNETospheric flow above the neutron-star surface. Such systems should be associated with super-Eddington accretion discs and low pulse fractions due to visibility selection and scattering in the disc wind. We suggest that many non-pulsating ultraluminous X-ray sources containing neutron stars may accrete in this shock-free regime.
[abstract 55 / 59] (score: 2) - Title: Variable opacity and accretion-column regimes of MAGNETized neutron starsAuthors: Galina Lipunova, Pavel Abolmasov,Comments: 8 pages, 8 figures; submitted to A&ASubjects: astro-ph.HECreated: 2026-09-23; Updated: 2026-09-24; Datestamp: 2026-09-24
Radiation-supported accretion columns of MAGNETized neutron stars can operate in several distinct regimes. As the accretion rate increases, MAGNETospheric accretion may proceed through hot-spot emission, efficiently cooling radiative shocks, and advective sinking columns. The structure of the accretion flow is determined by the global parameters such as MAGNETic field strength and mass accretion rate, but is also affected by opacity variations in strong MAGNETic fields. A decrease of opacity for photons with energy below the cyclotron energy is able to substantially augment the classical critical accretion rate separating efficiently cooling solutions from advective solutions. We propose an approach to determine the critical accretion rate above which the Basko-Sunyaev sinking solution becomes unavoidable. We also use the Basko-Sunyaev sinking solution to estimate the plasma temperature and compare the characteristic photon energy with the local cyclotron energy. For a combination of moderate MAGNETic fields and high accretion rates, the characteristic photon energy in advective columns typically exceeds the cyclotron energy. In this case, the opacity is not reduced by the MAGNETic field, and tall accretion columns are formed. Strong MAGNETic-field systems may retain short, efficiently cooling accretion columns over a wide range of super-Eddington accretion rates. We identify a region in accretion rate and MAGNETic-field strength where both efficiently cooling and advective solutions may coexist. In this region, the column may switch or oscillate between the regimes and geometries. The typical time of such oscillations are close to the replenishment time of the column, or to the thermal time near its bottom. The quasi-periodic oscillations, observed in some super-Eddington objects in the 1-100 mHz frequency range, may be related to such relaxation cycles.
[abstract 56 / 59] (score: 2) - Title: Gamma-ray emission toward supergiant shells in the Large Magellanic CloudAuthors: Qixin Yu, Olaf Reimer, Anita Reimer,Comments:Subjects: astro-ph.HECreated: 2026-09-23; Updated: 2026-09-24; Datestamp: 2026-09-24
The Large Magellanic Cloud (LMC), a satellite galaxy of our Milky Way, is considered to be a very good target for investigations of diffuse gamma-ray emission. Observations have shown that diffuse emissions are related to the large- and small-scale structures of the LMC. Particularly, it has been suggested that some of the small-scale bright diffuse emissions coincide with supergiant shells (SGSs) previously identified based on H$α$ images. We analyzed the gamma-ray emission from the LMC using more than 15 years of observations with the \textit{FERMI} Large Area Telescope in the energy range of 300$\,$MeV-300$\,$GeV. A dedicated spatial and spectral analysis was made for diffuse emission components of the LMC. Particularly, we evaluated the emissions from SGSs in detail using phenomenological approaches, and we established their corresponding spatial templates for gamma-ray emission. In the analysis of small-scale extended emissions, we detected seven H$α$-selected SGSs at a significance of more than $5σ$. The emission structure nested inside the SGSs appears to be a non-Gaussian feature and is very likely due to a modulated cosmic-ray distribution by an ensemble of SUPERNOVA remnant shocks. The spectra of the gamma-ray emission for most SGS regions favor a hadronic origin. For the large-scale diffuse emission from the LMC disk, our results suggest an interplay of hadron- and lepton-induced emission. The cosmic-ray proton energy density derived for bright SGSs is 3-10 times higher than that in the LMC disk. SGS$\,2$ was detected to be the most significant emission region among all SGSs. Based on the gamma-ray excess emission we detected in H$α$-selected SGSs in the LMC, we estimate that their contribution to the total diffuse gamma-ray emission in the LMC is at a non-negligible 41\% level.
[abstract 57 / 59] (score: 2) - Title: Alfvénic high-frequency oscillations at the pedestal of JET plasmasAuthors: Leonor Roque, Paulo Rodrigues, Emilia R. Solano, JET contributors, The Eurofusion Tokamak Exploitation Team,Comments: Submitted to Nuclear FusionSubjects: physics.plasm-phCreated: 2026-09-23; Updated: 2026-09-24; Datestamp: 2026-09-24
Long-lived ($\sim 10$ s) high-frequency oscillations (HFOs, $50-450$ kHz) near the plasma edge have been reported and experimentally described in L-H transition studies at JET and AUG. In this work, we show that these HFOs are a general phenomenon observed in various plasma scenarios and compositions (H$^1$, D, D-He$^3$, D-T) under different heating schemes, including pure Ohmic, ICRH and NBI. We demonstrate that dominant axisymmetric ($n=0$) HFOs are Global Alfvén eigenmodes (GAEs) tied to the shear-Alfvén continuum (SAC) minima arising at the plasma edge due to the sharp decrease of the density and increase of the safety factor. This hypothesis is corroborated by the remarkable agreement found between the measured frequencies of HFOs and the SAC minima computed by the ideal MHD code CSMISH for a comprehensive set of JET pulses. This result, along with the fact that HFOs are observed over long time windows and across a variety of plasma scenarios, makes them convenient MHD constraints for accurate equilibrium reconstruction near the edge. In view of this pragmatic application, we derive a first-order analytic expression for the two lowest coupled branches of the $n=0$ SAC, disclosing their dependence (and, consequently, that of the HFOs) on the plasma density, safety factor, and elongation profiles. In addition, we discuss the nature of $n\neq 0$ HFOs observed along with the dominant $n=0$ HFOs.
[abstract 58 / 59] (score: 2) - Title: Performance-portable GPU acceleration of the hybrid particle-in-cell code dHybridRAuthors: Bricker Ostler, Miha Cernetic, Damiano Caprioli,Comments:Subjects: astro-ph.HE physics.comp-ph physics.plasm-phCreated: 2026-09-23; Updated: 2026-09-24; Datestamp: 2026-09-24
Hybrid particle-in-cell simulations are widely used to study kinetic processes in collisionless astrophysical and space plasmas, yet the high computational cost of large-scale three-dimensional runs has largely confined production studies to two dimensions or restricted domains. To address this challenge, we present a performance-portable GPU implementation of the hybrid particle-in-cell code dHybridR. The implementation combines OpenMP target offloading with specialized SYCL kernels for the most computationally expensive operations, while preserving a unified CPU-GPU codebase that supports Intel, AMD, and NVIDIA GPUs. On the exascale supercomputers Aurora and Frontier, dHybridR achieves weak scaling efficiencies of $86\%$ to $97\%$ across 49,152 accelerators, and at 256 particles per cell, its full-node GPU throughput is up to $32\times$ that of the vectorized CPU implementation at approximately $90\%$ less energy per particle-update. To our knowledge, no other hybrid particle-in-cell code has reported GPU performance at this scale, leaving dHybridR uniquely positioned to exploit exascale systems. These advances substantially lower the computational barrier to large-scale three-dimensional hybrid-kinetic simulations of collisionless plasmas.
[abstract 59 / 59] (score: 2) - Title: First Pre-peak Ultraviolet Spectrum of a Tidal Disruption Event: A Fast Outflow Revealed Prior to Maximum Light in TDE2025aarmAuthors: Erica Hammerstein, Ryan Chornock, Jean Somalwar, Raffaella Margutti, Brenna Mockler, Olivia Aspegren, Itai Sfaradi, Natalie LeBaron, Jonathan Carney, Alexei V. Filippenko, A. J. Nayana, Igor Andreoni, Thomas Brink, Peter J. Brown, Adam J. Burgasser, S. Bradley Cenko, Suvi Gezari, Xiaoshan Huang, Mansi M. Kasliwal, Jon M. Miller, Sasha Mintz, Sam Rose, Peter Senchyna, Joshua D. Simon, Emma Softich, Robert Stein, Yuhan Yao, WeiKang Zheng, Richard Dekany, Matthew J. Graham, Russ R. Laher, Josiah Purdum, Ben Rusholme, Jesper Sollerman, Stefan van der Walt,Comments: 26 pages, 13 figures, 5 tables; submitted to ApJLSubjects: astro-ph.HECreated: 2026-09-23; Updated: 2026-09-24; Datestamp: 2026-09-24
The tidal disruption and eventual accretion of a star by a massive BLACK HOLE can lead to the launching of outflows and winds that encode important information about the tidal disruption and accretion processes. However, little is known about the existence and behavior of these outflows before optical light-curve peak, when processes such as stream-stream collisions and disk formation may be important. Here, we present the first pre-peak ultraviolet (UV) spectrum of a tidal disruption event (TDE), obtained $\sim 20$ days before optical maximum light of the nearby (redshift $z=0.0137$) TDE2025aarm, along with quasi-simultaneous infrared (IR) through X-ray observations. Our HST/STIS spectrum shows strong evidence for an early-time outflow through broad near-UV (NUV) and far-UV (FUV) absorption lines blueshifted by $\sim$10,000 km s$^{-1}$, including two new UV broad absorption features not yet identified in a TDE. We find that the FUV--IR continuum deviates significantly from a blackbody ($f_λ\propto λ^{-3.08}$), which we interpret as a signature of reprocessing through the outflow. This deviation implies that the bolometric luminosity in optical TDEs may be underestimated by a significant factor ($\sim$9 in this case) when inferred from single-temperature blackbody fits to NUV--optical photometry alone. This work further confirms that TDEs are capable of launching fast outflows at very early times and emphasizes the importance of prompt FUV spectroscopic observations of TDEs that can capture the full continuum emission and energetics.
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arXiv:2609.27397 [pdf, ps, other]
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arXiv:2510.20778 [pdf, ps, other]
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arXiv:2601.20953 [pdf, ps, other]
arXiv:2606.22758 [pdf, ps, other]
arXiv:2609.04118 [pdf, ps, other]
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arXiv:2609.26931 [pdf, ps, other]
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arXiv:2604.08687 [pdf, ps, other]
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