Current date: 2026-08-19
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Datestamp limit: 2026-08-19 (0 days ago)
Created/updated limit: 2026-08-12 (7 days ago)
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Scoring abstracts
Number of records retrieved: 759
Keyword score statistics
score 12 -- 1 abstracts
score 9 -- 1 abstracts
score 8 -- 3 abstracts
score 7 -- 3 abstracts
score 6 -- 1 abstracts
score 5 -- 4 abstracts
score 4 -- 9 abstracts
score 3 -- 7 abstracts
score 2 -- 10 abstracts
in total -- 39 abstracts
Articles that appeared on 2026-08-19
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[abstract 1 / 39] Wow! (score: 12)
- Title: Probing the $γ$-ray emission region and the connection to JET ejections in NRAO 150 with VLBIAuthors: L. C. Debbrecht, G. F. Paraschos, E. Ros, I. Agudo, T. P. Krichbaum, H. Müller, S. G. Jorstad, A. P. Marscher, M. A. Gurwell, J. A. Zensus,Comments: 8 pages, 4 figures, 3 tables; accepted for publication by A&ASubjects: astro-ph.HE astro-ph.GACreated: 2026-08-17; Updated: 2026-08-19; Datestamp: 2026-08-19
Relativistic JETs launched by ACTIVE GALACTIC NUCLEi are fundamental for understanding the physics of accreting supermassive BLACK HOLEs and their immediate environments, yet the origin of these JETs remains an open question. NRAO 150 is a BLAZAR with a complex RELATIVISTIC JET morphology that evolves on short timescales due to strong projection effects, enabling detailed kinematic analysis. In this study, we utilise data by the Very Long Baseline Array and the European VLBI Network from 2010 until 2019 at 43 GHz, to understand the formation and launching processes of the JET in NRAO 150. We study the $γ$-ray and radio light-curves, together with total intensity and linear polarisation information to probe the connection between flaring events, $γ$-ray emission, and the ejection of new JET features. Furthermore, we investigate the MAGNETic field configuration in the innermost JET region, as captured in polarised light, to gain insights about its configuration before, during, and after a $γ$-ray flare. Our results indicate a close temporal link between the $γ$-ray flaring activity and the ejection of new VLBI JET components, suggesting that the high-energy emission is produced downstream of the VLBI core. The combined kinematic and polarimetric evidence further points to a toroidal MAGNETic field in the inner JET, highlighting the key role of MAGNETic fields in governing both JET dynamics and high-energy emission in NRAO 150.
[abstract 2 / 39] Wow! (score: 9) - Title: X-ray Polarization Signatures from Comptonization by Magnetic Reconnection PlasmoidsAuthors: John Groger, Kun Hu, Henric Krawczynski,Comments: ApJL, acceptedSubjects: astro-ph.HECreated: 2026-08-17; Updated: 2026-08-19; Datestamp: 2026-08-19
Emission from X-ray binaries in the hard spectral state is dominated by high-energy radiation attributed to the Compton scattering of seed photons. The prevalent model of the Comptonization by hot electrons or pairs faces the problem of rapid radiative cooling of the emitting particles. A proposed alternative mechanism is the Comptonization by scattering off fast plasmoids formed during MAGNETic RECONNECTion. In this work, we simulate a simplified model of the plasmoid chain with Monte Carlo radiation transport and report on spectropolarimetric properties. We find that the Comptonization off trans-RELATIVISTIC bulk plasmoids is not only able to reproduce the 100 keV spectral cutoff, but furthermore produces X-rays that are above 1 keV strongly polarized perpendicular to the RECONNECTion layer. The POLARIZATION is stronger than that from the Comptonization by an isotropic hot plasma owing to the confinement of the motion of the scattering plasmoids in the plane of the RECONNECTion layer. The dependence of POLARIZATION on azimuthal viewing angle is discussed, along with possible locations for the plasmoid chain in an equatorial current sheet or the sheath of the BLACK HOLE's RELATIVISTIC JET.
[abstract 3 / 39] Wow! (score: 8) - Title: Exploring cosmic MAGNETism with GAMMA-RAY BURST afterglow emissionAuthors: Paolo Da Vela, Davide Miceli, Lara Nava, Giancarlo Ghirlanda,Comments: Accepted for publication in Astronomy & AstrophysicsSubjects: astro-ph.HECreated: 2026-08-18; Updated: 2026-08-19; Datestamp: 2026-08-19
The nature and origin of MAGNETic fields on cosmological scales are still unclear. Magnetic fields detected in galaxies and galaxy clusters are typically interpreted as the result of the amplification of weak seed fields, but their nature remains largely unknown with two scenarios considered: the cosmological and the astrophysical origin. Signatures of MAGNETization in cosmic voids from observations of very high energy (VHE, E > 100 GeV) photons from extragalactic sources can provide crucial results. Indeed, if a non-negligible intergalactic MAGNETic field (IGMF) is present in the voids, a time-delayed emission known as pair-echo is expected. The timing and intensity of this signal encode information on the IGMF strength B and properties. Given the recent detection of GAMMA-RAY BURST (GRB) afterglows at TeV energies, for this study we performed a detectability study of pair-echo signatures from GRBs. We simulated afterglow emission for different values of the JET kinetic energy (E$_{k,iso}$ = 10$^{49}$ - 10$^{55}$ erg), redshift (z = 0.03 - 1), and lightcurve break times, and estimated the expected pair-echo radiation for IGMF strengths in the range B = 10$^{-19}$ - 10$^{-16}$ G. We investigated the capability of CTAO to detect the resulting emission at tens of GeV. We find that a subsample of GRBs in the z - E$_{k,iso}$ parameter space can produce a detectable pair-echo component for CTAO for all the tested IGMF strengths. A steepening of the GRB afterglow light curve, caused e.g. by an early (0.1 - 1 days) JET break, is a key factor to increase the chances of detection. CTAO observations starting from 10 - 12 h after the GRB trigger and extending up to a few days can provide valuable information on the IGMF.
[abstract 4 / 39] Wow! (score: 8) - Title: Broadband emission of microQUASAR remnantsAuthors: Leandro Abaroa, Gustavo E. Romero, Valentí Bosch-Ramon,Comments: Accepted for publication in Astronomy & Astrophysics. 12 pages + appendicesSubjects: astro-ph.HECreated: 2026-08-17; Updated: 2026-08-19; Datestamp: 2026-08-19
MicroQUASAR remnants (MQRs), the long-lived cocoons inflated by extinct microQUASAR JETs, have recently been proposed as hidden Galactic PeVatrons capable of producing ultra-high-energy gamma rays without an active central engine. While hadronic interactions can account for bright gamma-ray emission from nearby clouds, the direct detection of MQRs remains challenging because their intrinsic emission is expected to be extended and of low surface brightness. In this work, we explore the broadband emission of MQRs by focusing on the leptonic component confined within the cocoon and on particle interactions in the shocked shell surrounding it. We model the injection and time-dependent transport of RELATIVISTIC particles, including stochastic re-acceleration driven by internal turbulence, treated as a second-order FERMI process. We consider sub-Eddington and super-Eddington microQUASAR systems and compute the resulting non-thermal emission from radio to gamma-ray energies, together with the thermal soft X-ray emission produced in the shocked shell. In the super-Eddington case, the intrinsic emission reaches peak values of $νL_ν\sim 10^{35}-10^{36}\,{\rm erg\,s^{-1}}$, whereas sub-Eddington remnants are typically several orders of magnitude fainter. At 1.3 GHz, the modeled cocoon surface brightness is of order $Σ_ν\sim 10^{-19}\,{\rm W\,m^{-2}\,Hz^{-1}\,sr^{-1}}$ for young powerful remnants and decreases rapidly as the remnant evolves. We find that the direct detectability of MQRs is therefore controlled mainly by surface brightness rather than by integrated luminosity. Powerful remnants may be detectable as extended SYNCHROTRON radio cocoons and shell-dominated soft X-ray structures, whereas sub-Eddington remnants are expected to be much harder to identify directly. Our results suggest that MQRs may constitute a hidden population of extended Galactic non-thermal sources.
[abstract 5 / 39] Wow! (score: 8) - Title: Evidence of self-organized criticality in the prompt emission of a bright GAMMA-RAY BURSTAuthors: Wen-Long Zhang, Wen-Jun Tan, Hao-Tian Lan, Shuang-Xi Yi, Shao-Lin Xiong, Chen-Wei Wang, Shuang-Nan Zhang, C. Guidorzi, R. Maccary, R. Moradi, Cheng-Kui Li, Sheng-Lun Xie, Wang-Chen Xue, Jia-Cong Liu, Zheng-Hang Yu, Yue Wang, Peng Zhang, Yan-Qiu Zhang, Chao Zheng, Jin-Peng Zhang, Fa-Yin Wang,Comments: 22 pages, 12 figures, accepted for publication in ApJLSubjects: astro-ph.HECreated: 2026-08-18; Updated: 2026-08-19; Datestamp: 2026-08-19
Gamma-ray bursts (GRBs) are the most energetic explosive events in the Universe, yet the physical mechanism of their prompt emission remains a mystery. Especially, it is unclear whether the energy dissipation mechanism in the GRB JET is dominated by kinetic energy or MAGNETic energy. Here, we studied the pulses in the prompt emission of the second brightest GRB to date, GRB 230307A, which was accurately measured by the Gravitational wave high-energy electroMAGNETic counterpart all-sky monitor (GECAM), with focus on the cumulative distributions of peak counts and duration of pulses as well as the waiting time between pulses. We find that these cumulative distributions show scale-invariant behavior, well consistent with the prediction of the self-organized criticality (SOC) theory. This is the first robust evidence of an SOC feature in the prompt emission of a single GRB. Moreover, the statistical properties of pulses in the prompt emission of GRB 230307A are very similar to those of solar flares. Our findings suggest that the prompt emission of GRB is powered by the dissipation of MAGNETic energy in the ultra-RELATIVISTIC JET, supporting the Poynting-flux-dominated prompt models.
[abstract 6 / 39] Wow! (score: 7) - Title: Particle Acceleration Time due to Turbulence-Induced Magnetic ReconnectionAuthors: Elisabete M. de Gouveia Dal Pino, Tania E. Medina-Torrejon,Comments: Accepted for publication in the ApJSubjects: astro-ph.HE hep-phCreated: 2026-08-17; Updated: 2026-08-19; Datestamp: 2026-08-19
We numerically investigate a crucial parameter for understanding particle acceleration theory via turbulence-induced MAGNETic RECONNECTion: the particle acceleration time. We examine particles accelerated either during the JET's dynamic evolution or in a post-processing, nearly stationary regime. We derive the particle acceleration time and compare it with theoretical predictions for both the FERMI and drift regimes identified in the simulations. In the FERMI regime, the acceleration time is expected to be independent of the particles' energy, for constant RECONNECTion velocity, as energy increases exponentially with time. Conversely, we expect the RECONNECTion acceleration time to depend on the current sheet's thickness and the RECONNECTion velocity, a dependence recently revisited by xu and lazarian 2023. They identified three conditions for \(t_{acc}\). We tested these relations using statistical distributions of the current sheets' thickness and RECONNECTion velocities in the turbulent JET over time. The resulting average value of \(t_{acc}\) was found to be nearly constant with particle energy. We compared this acceleration time with the average acceleration time derived directly from 50,000 particles accelerated in situ in the same RELATIVISTIC JET. When considering a longer time interval for particle acceleration in a nearly stationary snapshot of the turbulent JET, we find that the acceleration time during the FERMI regime remains nearly independent of particle energy and aligns with the acceleration time theoretical relations up to the threshold energy, attained when the particles Larmor radius becomes as large as the thickness of the largest current sheets. Beyond this threshold, the acceleration regime shifts to the slower drift regime, showing strong energy dependence, as predicted. The results also indicate a clear dominance of the FERMI regime of acceleration.
[abstract 7 / 39] Wow! (score: 7) - Title: Resolving Nearby Supermassive Black Holes with the Black Hole ExplorerAuthors: Yuto Akiyama, Kazunori Akiyama, Dominic W. Pesce, Daniel C. M. Palumbo, Angelo Ricarte, Paul Tiede, Marvin N. Martinez, Hikaru Yoshida, Avery E. Broderick, Aya E. Higuchi, Sara Issaoun, Neil M Nagar, Kotaro Niinuma, Venkatessh Ramakrishnan, Xinyue Alice Zhang,Comments: accepted for publication in the Publications of the Astronomical Society of the Pacific (PASP), 17 pages, 8 figuresSubjects: astro-ph.HE astro-ph.IMCreated: 2026-08-17; Updated: 2026-08-19; Datestamp: 2026-08-19
Recent Event Horizon Telescope results have demonstrated unique and transformative science in gravitational physics and BLACK HOLE astrophysics enabled by event-horizon-scale imaging of supermassive BLACK HOLEs (SMBHs). Nevertheless, the angular resolution of current ground-based very long baseline interferometry (VLBI) arrays limits such studies to only two sources, precluding systematic investigations of horizon-scale emission across a nearby SMBH population. The proposed Black Hole Explorer (BHEX), a millimeter/submillimeter space VLBI mission, would overcome this limitation by delivering substantially higher angular resolution. Here, we present a series of simulated observations to assess a population of nearby horizon-scale targets accessible with BHEX. Based on a recently developed SMBH number density model, we find that BHEX could infer BLACK HOLE masses for ~70-90 sources from size measurements, constrain MAGNETic field structures through linear POLARIZATION imaging for ~20-30 sources, and resolve BLACK HOLE shadows for ~20-25 sources. Targeted observations of ~50 nearby SMBHs are expected to yield measurements for ~30 source sizes and ~10 shadows and linear-POLARIZATION patterns. These projections are supported by detailed imaging simulations of general RELATIVISTIC MAGNETohydrodynamic (GRMHD) models for eleven nearby SMBHs. Together, our results highlight BHEX as a powerful facility for revealing the demographics of SMBH properties across diverse accretion states, radio loudness, host galaxy environments, and viewing geometries.
[abstract 8 / 39] Wow! (score: 7) - Title: The Gamma-ray Burst Jet Energy Distribution Suggests A Quasi-universal, Weakly Magnetized Jet Evolving Over Cosmic TimeAuthors: Nicole M. Lloyd-Ronning, Fabio De Colle, Gal Birenbaum, Omer Bromberg, Jarrett Johnson,Comments:Subjects: astro-ph.HECreated: 2026-08-17; Updated: 2026-08-19; Datestamp: 2026-08-19
We present distributions of GAMMA-RAY BURST observed and inferred properties for those GRBs with redshifts. We show that the isotropic energy distribution, which spans over four orders of magnitude, can be reproduced reasonably well under a simplistic assumption that every observed GRB originates from a quasi-universal JET with roughly the same decreasing power-law profile of energy as a function of angle, with a power-law index of $ 3 \lesssim ζ\lesssim 4$. The spread in the observed distribution can be explained by the variation in observer viewing angle alone. Furthermore, this power-law JET structure provides an even better fit to both the isotropic energy and luminosity distributions if the isotropic energy normalization evolves as a function of redshift in a manner that has been suggested by a range of previously published studies. The relatively steep power-law index of this JET is consistent with the structure predicted by simulations of weakly MAGNETized JETs in collapsars, whereas simulations of hydrodynamic JETs predict a structure shallower than what we find here. The predicted afterglow light curves within this model framework show steepening behavior at times commensurate with observed JET break times.
[abstract 9 / 39] Yes (score: 6) - Title: A Critical Eddington Ratio for X-Shaped Radio GalaxiesAuthors: David Garofalo,Comments: ApJSubjects: astro-ph.GACreated: 2026-08-17; Updated: 2026-08-19; Datestamp: 2026-08-19
We derive a quantitative condition for the formation of X-shaped RADIO GALAXies by evaluating the competition between BLACK HOLE spin evolution and the radiative fading of relic plasma within our previously proposed framework. The simultaneous visibility of two JET axes requires that the timescale for spin evolution across zero, t_trans, be shorter than the fading timescale of relic radio emission, t_fade. We estimate the transition timescale as t_trans about 5 million /lambda yr, where lambda is the Eddington ratio, and derive a visibility timescale t_fade about equal to 5-20 Myr based on the evolution of the SYNCHROTRON break frequency for typical lobe MAGNETic fields and redshifts. This leads to a critical Eddington ratio lambda_crit in the range 0.3-1, above which systems can exhibit X-shaped morphologies. We show that this threshold naturally produces an environmental dependence, as radiatively efficient accretion is more readily sustained in low-density environments, while feedback in rich clusters tends to drive systems toward radiatively inefficient states with a larger fraction of systems having lambda much less than lambda_crit, suppressing XRG formation. We further demonstrate that the observed low fraction of X-shaped RADIO GALAXies (about 1-5%) arises from the limited overlap window combined with geometric and detectability effects. These results provide a quantitative and testable extension of our previous model, linking X-shaped morphology to accretion rate and environmental conditions through a simple timescale criterion.
[abstract 10 / 39] Yes (score: 5) - Title: GRB 260310A / SN 2026fgk: A Multi-Wavelength Study of a Nearby Underluminous Long GRB and SN with a Complex AfterglowAuthors: Ramandeep Gill, Rosa L. Becerra, Antonio de Ugarte Postigo, Christina C. Thöne, Alan M. Watson, Noémie Globus, Jean-Grégoire Ducoin, Peter Veres, Stanley E. Kurtz, Asuka Kuwata, Antonio Martín-Carrillo, Luca Izzo, Christophe Adami, Enrique Moreno Méndez, Nikos Mandarakas, Camila Angulo-Valdez, Stéphane Basa, William H. Lee, Edilberto Aguilar-Ruiz, Dalya Akl, Margo F. Aller, Miguel Ángel Aloy, Jie An, Sarah Antier, Jean-Luc Atteia, Nathaniel R. Butler, Krittapas Chanchaiworawit, Philipe V. De La Parra, Damien Dornic, Francis Fortin, Shaoyu Fu, Johan P. U. Fynbo, Lluis Galbany, Leonardo García-García, Stefan Geier, Marion Guelfand, Linbo He, Shuaiqing Jiang, Emeric Le Floc'h, Massimiliano Lincetto, Xing Liu, Gianluca Lombardi, Diego López-Cámara, Daniele Bjørn Malesani, Francesco Magnani, Kanthanakorn Noysena, Margarita Pereyra, Ny Avo Rakotondrainibe, Anthony C. S. Readhead, Delphine Russeil, Fredd Sánchez-Álvarez, Benjamin Schneider, Tirth D. Surti, Nial R. Tanvir, Samaporn Tinyanont, Dong Xu, Zipei Zhu,Comments: Accepted to MNRASSubjects: astro-ph.HECreated: 2026-08-18; Updated: 2026-08-19; Datestamp: 2026-08-19
We present a comprehensive multi-wavelength study of GRB 260310A / SN 2026fgk, a nearby ($z=0.153$), long-duration GAMMA-RAY BURST (GRB) with an exceptionally underluminous prompt $γ$-ray emission and a Comptonized spectrum. The burst occurred at the edge of a blue host galaxy at a projected distance of 15 kpc, which is one of the largest offsets reported for a long GRB. The bright optical afterglow, with dense coverage from COLIBRÍ, likely peaked at a few to several hours post-burst, followed by a shallow decay not expected from canonical afterglow models. Both the optical and X-ray light curves show a brief chromatic plateau from $4-7$ days. We show that the subsequent rebrightening observed at $\sim20$ days is best explained by the combined contribution of the associated Type Ic-BL SUPERNOVA, identified in GTC spectra, and a late-time refreshed shock. The broadband optical to X-ray spectral energy distribution is well described by SYNCHROTRON emission from the forward shock, while the radio observations demand an additional emission component. We model the afterglow using (a) an on-axis uniform JET from a dirty fireball with late-time energy injection and (b) a misaligned JET with power-law angular structure, both having material emitting along our line-of-sight (LOS) moving with an initial Lorentz factor of $Γ_0\sim20-35$. We conclude that at more typical GRB distances ($z\gtrsim0.5$) the prompt $γ$-ray emission from this source would likely have escaped detection, whereas its optical afterglow would have remained observable, making the event appear as an orphan afterglow or a gamma-ray quiet fast X-ray transient.
[abstract 11 / 39] Yes (score: 5) - Title: A Cross-Band (X-ray $\times$ Optical) Periodicity Search for Supermassive Black Hole Binaries: A Null Result and the First Completeness-Corrected ConstraintAuthors: Karan Akbari,Comments: Accepted for publication in ApJ. 21 pages, 11 figures, 1 table. Code and result tables: doi:10.5281/zenodo.21386388Subjects: astro-ph.HE astro-ph.GA astro-ph.IMCreated: 2026-08-18; Updated: 2026-08-19; Datestamp: 2026-08-19
We present the first sample-level search for supermassive BLACK HOLE binaries (SMBHBs) requiring coherent quasi-periodicity at a common period in the X-ray and optical bands, over 1194 SWIFT-BAT hard X-ray AGN (Stage 1) and 175 4XMM-DR14 AGN (Stage 2). No source is a co-periodic candidate. Each light curve is modelled as a damped random walk (DRW) and searched with a Lomb-Scargle periodogram and a look-elsewhere-corrected Monte-Carlo significance. Because DRW red noise is largely independent between corona and disc, we require both bands individually significant with periods coincident within 5%, and gate the survivors with the model-independent null-signal-template test of Robnik et al. (2024). Over $P=100$-$900$ d the completeness-corrected 95% upper limit on the co-periodic fraction is amplitude-dependent: $\lesssim 3\%$ for hard-X-ray fractional modulation $\gtrsim 0.3$, $\approx 15\%$ (precision-limited) at 0.2, and uninformative below $\sim 0.15$ (the $ε=1$ floor is 0.25%). The sensitivity is set by the hard X-ray monitoring, not the optical photometry or the statistics, the opposite of the usual assumption. Daily MAXI and RXTE/ASM monitoring of the brightest AGN raises the X-ray completeness 5-8-fold, and the search remains null. Integrated over the BAT black-hole mass function, the expected all-amplitude co-periodic fraction is $\sim 3\times10^{-2}\, f_{\rm bin}\, δ_{\rm mod}$ (modulo a factor $g<1$), with $f_{\rm bin}$ the sub-pc binary fraction, $δ_{\rm mod}$ the modulating duty cycle, and $g$ the fraction reaching recoverable hard-X-ray amplitude, so a null is expected. We deliver a validated cross-band framework and the first completeness-corrected constraint on the co-periodic fraction, ready for the denser X-ray monitoring of Einstein Probe and eROSITA.
[abstract 12 / 39] Yes (score: 5) - Title: Modelling mountains on accreting MAGNETized neutron starsAuthors: T. Brusco, B. Haskell, M. Razzano, M. Bejger, J. L. Zdunik,Comments:Subjects: astro-ph.HE gr-qcCreated: 2026-08-18; Updated: 2026-08-19; Datestamp: 2026-08-19
Continuous gravitational waves from accreting neutron stars in Low Mass X-ray Binaries are one of the main targets for current and next generation ground based detectors. In order to select the most promising astrophysical sources, however, reliable predictions for the signals are required, and it is therefore necessary to develop models that consistently account for the combined effects of MAGNETic stresses, accretion-induced heating, and the elastic response of the crust.}{We present a model for computing the quadrupolar deformation, incorporating for the first time the coupled effects of a poloidal MAGNETic field, deep crustal heating, and crustal elasticity. Perturbations to the star's structure driven by the Lorentz force density and by thermally-induced density variations are computed by solving a system of linearised deformation equations in the crust, for which we consider the full elastic response, while the ocean and core treated as barotropic fluids. We identify a threshold accretion rate whose value depends on crustal microphysics and the superfluid gaps in the core, above which MAGNETic stresses and asymmetric accretion drive deformations of opposite sign, while below this threshold their roles are reversed. The predicted eccentricities reach magnitudes up to $\varepsilon\sim 10^{-11}$, corresponding to characteristic gravitational-wave strains accessible to next-generation detectors such as the Einstein Telescope or Cosmic Explorer, but generally below the sensitivity of current LIGO, Virgo and KAGRA interferometers. These results are consistent with the non-detection of continuous gravitational waves from accreting neutron stars in Low Mass X-ray Binaries in recent observational campaigns, but highlight the need of reliable models to understand the impact of gravitational wave emission in these systems and select relevant targets for future searches.
[abstract 13 / 39] Yes (score: 5) - Title: From Variability to SED Modeling: A Multiwavelength Study of the Neutrino Blazar TXS 0506+056Authors: Shiyu Du, Hanxiao Xia, Jianghua Wu, Yue Fang,Comments: Accepted for publication in The Astrophysical Journal. 20 pages, 12 figuresSubjects: astro-ph.HE astro-ph.GACreated: 2026-08-18; Updated: 2026-08-19; Datestamp: 2026-08-19
The BLAZAR TXS 0506+056 is the first source that was reported to be associated with high-energy extragalactic neutrino events and is one of the major targets for multi-messenger studies. We carried out multi-wavelength optical monitoring of this object on 24 nights in the period from 2018 to 2023. The overall light curves exhibit a dimming trend superposed by some small-amplitude fluctuations, and intraday variability was detected on four nights. Bluer-when-brighter behaviors were observed on both intraday and long timescales and were more pronounced on long timescales, while a weak redder-when-brighter trend was detected on one night. No significant time lags were found between variations at different optical wavelengths. We also retrieved the multi-broadband data from some monitoring programs. The data reveal complex, asynchronous flaring in different wavebands. A cross-correlation analysis shows that the high-energy emission (optical to gamma-ray) is co-spatial and leads the radio emission by a substantial time of about 800 to 900 days, suggesting that the radio emission originates from a downstream region of the JET. We performed time-dependent lepto-hadronic modeling of the spectral energy distributions for three representative epochs, the 2017 neutrino-associated flare, a post-flare phase, and a deep quiescent state, revealing an evolution in the radiative properties of the emission regions. The modeling results provide a phenomenological framework for interpreting the long-term multiwavelength behavior of TXS 0506+056 in a multi-messenger context.
[abstract 14 / 39] Yes (score: 4) - Title: New constraints on axion with gamma-ray observations of the Crab NebulaAuthors: Kazunori Kohri, Haruki Takahashi,Comments: 24 pages, 5 figures, published in Phys. Rev. DSubjects: hep-ph astro-ph.CO astro-ph.HECreated: 2026-08-18; Updated: 2026-08-19; Datestamp: 2026-08-19
In this paper, we derive the upper bounds on the coupling of axion-like particles (ALPs) with photon as a function of the mass by considering axion-photon conversion in the Crab Nebula. Previous studies have not considered the influence of the MAGNETic field within the Crab Nebula. The MAGNETic field plays a crucial role through the Synchrotron Self-Compton (SSC) process, in which high-energy electrons produce SYNCHROTRON radiation that is subsequently up-scattered by the same electrons via inverse Compton scattering to generate gamma rays. Therefore, neglecting the MAGNETic field in modeling leads to theoretical inconsistencies. In this work, we investigate the significance of the MAGNETic field effect and demonstrate that even differences in MAGNETic field modeling can substantially alter the conversion probability. We thus, for the first time, point out that proper consideration of the MAGNETic field is essential in ALP searches using gamma rays from the Crab Nebula. The resulting constraints reach up to a coupling of $g_{aγγ} \lesssim 1 \times 10^{-11} {\rm GeV}^{-1}$ for ALP masses in the range $10^{-10} {\rm eV} \lesssim m_a \lesssim 10^{-6} {\rm eV}$.
[abstract 15 / 39] Yes (score: 4) - Title: Ruling Out Spiky WIMP Dark Matter using Indirect SearchesAuthors: Dibya S. Chattopadhyay, P. S. Bhupal Dev, Yago Porto,Comments: 24 pages, 7 figures; matches the version published in Journal of Cosmology and Astroparticle PhysicsSubjects: hep-ph astro-ph.GACreated: 2026-08-17; Updated: 2026-08-19; Datestamp: 2026-08-19
The DARK MATTER (DM) density profile in the innermost region of the Galaxy remains an open question. In particular, while adiabatic growth of the supermassive BLACK HOLE Sgr A$^\ast$ at the Galactic Center (GC) can induce a 'spike' in central DM density, the existence of such a spike is still under debate. Here we present new constraints on the spike slope $γ_{\rm sp}$ using conventional DM indirect detection searches. We first recast existing photon and neutrino line searches, which include the contribution from the GC region, into constraints on the thermally-averaged DM annihilation cross section $\langleσv\rangle$ in the presence of a DM spike. We then derive new bounds on the spike profile for a generic Weakly Interacting Massive Particle (WIMP) DM scenario, where the thermal freeze-out mechanism fixes the annihilation cross-section at $\langleσv\rangle\sim (2-3) \times 10^{-26}~{\rm cm}^3~{\rm s}^{-1}$. We find that, for DM annihilation to photons, existing \emph{FERMI}-LAT and MAGIC data place strong constraints on spike profiles at the GC over a broad range of WIMP DM masses, from 10 GeV to 100 TeV, for photon branching fractions down to $\sim 10^{-2}$, and remain sensitive to values as small as $\sim 10^{-4}$ in parts of the parameter space. For the neutrino channel, we use the recent IceCube data to constrain the existence of an extremely steep spike in the $\mathscr{O}(1-10)$~TeV DM mass range. Our analysis can be easily extended to other annihilation channels.
[abstract 16 / 39] Yes (score: 4) - Title: Extreme-Mass-Ratio Inspirals in Gaseous DisksAuthors: Alexander J. Dittmann, Abhishek Hegade K. R., Callum W. Fairbairn,Comments: 18 pages, 14 figures, supplementary mathematica notebook in the source file. Comments welcome!Subjects: astro-ph.HE gr-qcCreated: 2026-08-17; Updated: 2026-08-19; Datestamp: 2026-08-19
Gravitational waves from extreme mass ratio inspirals (EMRIs) are precise probes of the environment of the supermassive BLACK HOLEs (SMBHs) they orbit. If an SMBH is actively accreting, the surrounding gaseous disk can impart hydrodynamic torques on and assist the formation of EMRIs within it. Such disk-EMRI interactions could leave measurable imprints on future observations by the Laser Interferometer Space Antenna (LISA), and potentially provide a route to constrain disk properties using gravitational wave observations. We present herein a detailed RELATIVISTIC analysis of these hydrodynamic interactions using linear theory. We first derive a Lagrangian governing the evolution of spiral density waves in the disk and use it to formulate a balance law for the transfer of angular momentum between the EMRI and disk. We then develop a stable numerical scheme which can be used to treat corotation resonances and find modal solutions in thin disks up to very large azimuthal numbers. Using this numerical scheme, we explore how SMBH spins, EMRI semi-major axes, disk scale heights, sound speed gradients, and surface density gradients affect the interaction between accretion disks and circular EMRIs. Our results show that RELATIVISTIC effects substantially alter disk-EMRI interactions once the secondary orbit is within $\mathcal{O}(25)$ Schwarzschild radii from the SMBH. Comparing our numerical results with recent analytical models suggests that the impact of pressure gradients and softening of the gravitational potential is important for disks with finite thickness and cannot be captured by tuning the torque cutoff parameters in the analytical models. The framework provided here will help analyze the formation scenarios of EMRIs and build RELATIVISTICally accurate waveform models of disk-EMRI interactions.
[abstract 17 / 39] Yes (score: 4) - Title: The X-Ray Continuum Emission Region in the Lensed Quasar SDSS J133907.23+131038.6 is Much Smaller than the Accretion DiskAuthors: Christopher W. Morgan, James B. Margeson, Gilberto Garcia, Xinyu Dai, Luis J. Goicoechea, Vyacheslav N. Shalyapin, George Chartas,Comments: 12 pages, 10 figures, accepted for publication in ApJSubjects: astro-ph.HE astro-ph.GACreated: 2026-08-17; Updated: 2026-08-19; Datestamp: 2026-08-19
We analyze microlensing variability in 15 seasons of optical monitoring data and 4 epochs of new X-ray observations of the doubly-imaged gravitationally lensed QUASAR SDSS J133907.23+131038.6 to place empirical constraints on the size and structure of that system's X-ray and optical continuum emission regions. Employing a Bayesian Monte Carlo method, we analyzed ground-based optical light curves to constrain the half-light radius of the far-UV source $\log(r_{\rm 1/2, FUV}/{\rm cm})=15.78^{+0.26}_{-0.28}$ at 193 nm, the rest-frame center of the {\it r}-band, assuming a $60^\circ$ inclination angle. This size corresponds to $\sim100\,{\it r}_{\rm g}$ for a $4.0 \times 10^{8} \: {\rm M_{\odot}}$ BLACK HOLE. We measured the half-light radius of the full band ($0.2-8.0 \: {\rm keV}$) X-ray continuum emission region $\log(r_{\rm 1/2, X_{full}}/{\rm cm})=14.32^{+0.23}_{-0.31}$, a size measurement that is consistent with the radius of the innermost stable circular orbit (ISCO) in the Schwarzschild metric.Two shifted Fe K$α$ lines caused by microlensing are detected in the stacked spectrum of image A at 5.9 and 8.9~keV at $>99\%$ significance.
[abstract 18 / 39] Yes (score: 4) - Title: AT 2020afjz (TSS2020a): The First Fast Extragalactic Transient Discovered by TESSAuthors: Ryan Ridden-Harper, Hugh Roxburgh, Clarinda Montilla, Lancia Hubley, James Freeburn, Brayden Leicester, Andrew Moore, Zachary G. Lane, Jaime Luisi, Koji Shukawa, Armin Rest, Jeff Cooke, Michele T. Bannister, Lilly Fox, Tait Keller, Qinan Wang,Comments: 21 pages, 10 figures, 6 tables. Submitted to AAS journalsSubjects: astro-ph.HE astro-ph.COCreated: 2026-08-18; Updated: 2026-08-19; Datestamp: 2026-08-19
We report the discovery of AT 2020afjz (TSS2020a): the first hour-scale extragalactic transient discovered in optical wavelengths whose complete evolution -- from explosion onset to decay -- is temporally resolved, and the first such transient discovered by TESS. AT 2020afjz was identified as a $>10σ$ detection in the pilot HiLaTS program run within the TESSELLATE Sky Survey, which blindly searches for transient phenomena in TESS data with the TESSELLATE pipeline. Through cross-matching with legacy imaging, we associate it with DES J042144.37$-$383311.3, a member of an interacting galaxy pair at $z_{\rm phot}=0.67^{+0.07}_{-0.10}$. While AT 2020afjz is similar in duration and brightness to GRB afterglows, it exhibits a slow rise time of $\sim1$ hr and lasts for only 2.4 hr above the half-max brightness; modeling the TESS light curve with VegasAfterglow finds that it is best described as either an on-axis "dirty-fireball" or off-axis orphan afterglow. Each of these rare classifications hinge upon a non-detection at gamma-ray energies, but as FERMI-GBM was Earth-occulted at the time of explosion, AT 2020afjz's gamma-quiet nature cannot be definitively confirmed. Regardless, AT 2020afjz demonstrates TESS's power to discover fast extragalactic transients, and heralds a new population awaiting discovery with TESSELLATE.
[abstract 19 / 39] Yes (score: 4) - Title: Sudden emergence of a low-frequency hard X-ray lag in the Seyfert 1 galaxy Mrk 1044Authors: Jia-Lai Kang, Jun-Xian Wang,Comments: 13 pages, 7 figures, accepted by ApJ. Comments are very welcome!Subjects: astro-ph.HECreated: 2026-08-18; Updated: 2026-08-19; Datestamp: 2026-08-19
Hard X-ray lags, where low frequency variations in the hard X-ray band lag behind those in the soft band, have been detected in many ACTIVE GALACTIC NUCLEi (AGNs) and are generally attributed to the inward propagation of accretion-flow fluctuations through an extended corona. In a long XMM-Newton observation of the Seyfert 1 galaxy Mrk 1044, we found a remarkable transition in the lag behavior within a single exposure, while the X-ray flux and spectral shape remained largely unchanged. During the first 60 ks, no significant hard X-ray lag was detected, whereas in the subsequent 60 ks, a pronounced lag emerged. The lag was so prominent that a large-amplitude flux variation event during the lag-detected interval, characterized by a gradual dimming followed by recovery, produced a remarkable clockwise loop in the flux-softness diagram. The sudden appearance of the hard X-ray lag suggests that the X-ray corona underwent a rapid transition from a compact to an extended configuration. This scenario is further supported by two independent observational signatures: (1) the variability became noticeably smoother, with a redder power spectral density (PSD), during the lag-detected interval, and (2) the broad Fe K$α$ line profile became narrower and the reflection continuum weaker. These findings highlight the diagnostic power of tracking rapid changes in hard X-ray lags for probing the physical structure and evolution of AGN coronae, and demonstrate that identifying prominent loops in the flux-softness diagram provides an effective way to locate intervals with significant hard X-ray lags.
[abstract 20 / 39] Yes (score: 4) - Title: The FLARE FacilityAuthors: Hantao Ji, Jongsoo Yoo, Peiyun Shi, Euichan Jung, Kush Maheshwari, Adam Robbins, Sunghyun Son, Adam Stanier, Yang Ren, Sayak Bose, Dylan Corl, Keith Corrigan, Robert Cutler, William Daughton, Robert Ellis, Geoffrey Gettelfinger, Ronald Hatcher, Philip Heitzenroeder, Frank Hoffmann, Jonathan Jara-Almonte, Michael Kalish, Thomas Kozub, Enrique Merino, Weiguo Que, Benjamin Smith, John Wallace, Xin Zhao, Sofia Avrutsky, Neal Crocker, Seth Dorfman, Yuka Doke, Corina Dunn, William Fox, Boting Li, Xiaocan Li, Clayton Myers, Shohgo Okazaki, Joshua Pawlak, Tongnyeol Rhee, Byonghoon Seo, Taiju Suzuki, Yang Zhang, Stuart Bale, Amitava Bhattacharjee, Troy Carter, Chuanfei Dong, James Drake, Jan Egedal, Erik Gilson, Michiaki Inomoto, Jonathan Menard, Yasushi Ono, Stewart Prager, John Sarff, Hiroshi Tanabe, Masaaki Yamada,Comments: 47 pages, 25 figures, 7 tablesSubjects: physics.plasm-ph astro-ph.HE astro-ph.IM astro-ph.SR physics.space-phCreated: 2026-08-18; Updated: 2026-08-19; Datestamp: 2026-08-19
The Facility for Laboratory Reconnection Experiments (FLARE) has been constructed to study MAGNETic RECONNECTion in multiple X-line regimes relevant to space, astrophysical, and fusion plasmas. Building upon the successful design of the Magnetic Reconnection Experiment (MRX), FLARE features a larger physical volume, stronger MAGNETic fields, and an independent ohmic heating drive to significantly extend the accessible parameter space, targeting Lundquist numbers up to S ~ 10^5 and normalized system sizes up to λ~ 10^3. This paper details the facility's core engineering components, including the primary vacuum vessel, internal flux cores, highly segmented external coil systems, modular capacitor banks, and the safety interlock and control architecture. An initial diagnostic suite is presented, comprising high-resolution 2D MAGNETic probe arrays, triple Langmuir probes, a fully fiber-coupled interferometer, ion Doppler spectroscopy, and fast camera imaging. Initial operations demonstrate the device's experimental flexibility and reliability, successfully executing symmetric push-pull RECONNECTion, spheromak merging, and asymmetric downstream configurations. Currently operating within "Stage 2.5" with S ~ 2,500 and λ~ 60 for anti-parallel RECONNECTion, FLARE provides immediate access to the multiple X-line regimes. Planned hardware upgrades, advanced diagnostic additions, and integration with fully kinetic simulations will further expand its capabilities as it transitions into a collaborative user facility for the broader plasma science community.
[abstract 21 / 39] Yes (score: 4) - Title: The high entropy of the UHECR arrival direction distribution favors a light compositionAuthors: Nimrod Strasman, Eli Waxman,Comments:Subjects: astro-ph.HECreated: 2026-08-18; Updated: 2026-08-19; Datestamp: 2026-08-19
We analyze the constraints on the composition of ultra-high-energy COSMIC RAYs (UHECRs), and on the density and distribution of their sources, that may be inferred from their arrival-direction distribution, using a novel semi-analytical description of the propagation energy loss of atomic nuclei ($A>4$) with energy $>2\times10^{19}~\text{eV}$, that allows generating UHECR arrival maps faster than by using detailed propagation simulations and yields insights to the impact of propagation energy loss. We show that the anisotropy of the UHECR arrival direction distribution due to the large-scale structure (LSS) of matter distribution is larger for heavy nuclei composition compared to protons, despite their larger deflections by MAGNETic fields, due to their shorter propagation distance and weaker dependence of rigidity on observed energy. Identifying the LSS anisotropy signal is hampered for heavy nuclei due to their large deflections by the uncertain Galactic MAGNETic field (GMF). We introduce a new measure of anisotropy, an "entropy" of the arrival-direction distribution, that is largely independent of the GMF configuration and has strong discriminating power between heavy- and light-composition models. Analyzing the public $>3.2\times10^{19}$~eV Auger data, we show that the correlation with the LSS on large angular scales is weak and requires a low source density, $s_0\le10^{-4}{\rm Mpc}^{-3}$, to allow masking the LSS signature by "cosmic-variance" ($s_0=10^{-2}{\rm Mpc}^{-3}$ is ruled out at $>99\%$ confidence level (CL)). The high entropy of the distribution is consistent with proton models and inconsistent with heavy nuclei models at $>96\%$ CL for $s_0\ge10^{-5}{\rm Mpc}^{-3}$. Reducing the absolute energy calibration uncertainty may allow detection of the LSS correlation for proton models (increased exposure alone will not suffice due to the dominance of cosmic variance).
[abstract 22 / 39] Yes (score: 4) - Title: Control of Magnetic Reconnection in High Energy Density PlasmasAuthors: J. L. Latham, B. K. Russell, C. Dong, C. A. Walsh, K. G. Miller, P. T. Campbell, L. Willingale, P. Nilson, K. Krushelnick,Comments: 23 pages, 6 figuresSubjects: physics.plasm-phCreated: 2026-08-18; Updated: 2026-08-19; Datestamp: 2026-08-19
Magnetic RECONNECTion governs the explosive release of MAGNETic energy in systems from the solar corona to fusion plasmas, yet controlling it in the laboratory has remained out of reach. Here we demonstrate active control of RECONNECTion in high-power LASER-driven plasmas using a third, RELATIVISTIC-intensity LASER pulse that injects filaments of electron current into the RECONNECTing system. Two moderate-intensity LASERs drive colliding MAGNETized plumes that RECONNECT, forming plasmoids in the current sheet as seen in proton deflectometry. The RELATIVISTIC LASER generates MAGNETic fields matching the polarity on either side of the layer, and, depending on its arrival time, either accelerates the breakup of the current sheet or suppresses RECONNECTion. Arriving early, before the plumes strongly interact, it builds a pocket of MAGNETic pressure that repels them via flux pileup; arriving after the current sheet forms, it accelerates electrons that extend current filamentation instabilities into the upstream, causing rapid dissipation of the RECONNECTing MAGNETic field. This approach opens a route to steering MAGNETic energy flow in fusion plasmas and broadens the range of systems accessible to laboratory astrophysics.
[abstract 23 / 39] (score: 3) - Title: Radial dust distributions and obscuring geometry in AGN from JWST/MIRI spectroscopyAuthors: Ruiyu Pan, Arkaprabha Sarangi,Comments: 18 pages, 9 figuresSubjects: astro-ph.GA astro-ph.HECreated: 2026-08-18; Updated: 2026-08-19; Datestamp: 2026-08-19
The spatial distribution of obscuring dust in ACTIVE GALACTIC NUCLEi (AGN) is critical for distinguishing between static torus models and dynamical disk-wind scenarios. To constrain this geometry, we forward-model the rest-frame $5$--$14\,μ\mathrm{m}$ JWST/MIRI MRS spectra of 25 local AGN using a three-dimensional, axisymmetric radiative-transfer library combined with empirical starburst templates. Using a grid-based inference framework, we systematically compare radial dust-density laws of the form $n(r)\propto r^{-p}$ over the range $p=0.5$--$2.0$. Our model comparison strongly favours shallow radial profiles at the sample level: 20 sources achieve their largest statistical weight at $p=0.5$, and 21 accumulate more than half of their combined density-law weight at $p\leq1$. This tendency remains robust even when the likelihood power $β$ is varied, although the preferred profile of individual sources can change. Furthermore, the $9.7\,μ\mathrm{m}$ silicate feature exhibits a distinct trend: absorption minima remain near $9.7\,μ\mathrm{m}$, whereas four observed emission maxima are shifted redward by approximately $0.8$--$1.3\,μ\mathrm{m}$. These results favour relatively extended MIR-emitting dust distributions rather than strictly compact geometries, and suggest that an interplay of radiative-transfer effects and intrinsic dust grain properties drives the observed spectral diversity.
[abstract 24 / 39] (score: 3) - Title: Detection of Quasiperiodic Oscillations in the Blazar PKS 0735+178 with TESSAuthors: Shubham Kishore, Alok C. Gupta, Paul J. Wiita, Sandeep K. Mondal, M. Vivek,Comments: Accepted for publication in MNRAS, 10 pages, 7 figures, 1 tableSubjects: astro-ph.HECreated: 2026-08-18; Updated: 2026-08-19; Datestamp: 2026-08-19
We report here the detection of signatures of a quasiperiodic oscillation (QPO) and a short flare in the optical light curve of the BLAZAR PKS 0735+178, observed in two sectors, 71 and 72, spanning around 49 days with the Transiting Exoplanet Survey Satellite. The modest flare in sector 71 lasted ~4.3 days and appears as a combination of two sub-flares. In sector 72, a transient QPO with a period ~11.2 hours is detected at local and global significance levels of 4.11$σ$ and 3.06$σ$, respectively. We used weighted wavelet z transform, Lomb-Scargle periodogram, and phase dispersion minimization analysis techniques to look for and confirm the QPO feature. We also performed a segment-wise statistical inspection of these light curves and discuss here possible mechanisms that could explain the observed flux behavior.
[abstract 25 / 39] (score: 3) - Title: Microcoulomb-level electron beam and multi-Joule hard X-rays driven by a high-efficiency LASER-plasma acceleratorAuthors: B. Mahieu, L. Ribotte, W. Cayzac, G. Boutoux, R. Parreault, J. Gastineau, E. Lamoine, F. Audo, R. Babjak, D. Batani, N. Blanchot, J. L. Bourgade, M. Brochier, T. Caillaud, P. Canel, S. Cavaro, C. Chappuis, S. Debesset, R. Diaz, E. D Humieres, W. Duchastenier, R. du Jeu, A. Duval, B. Etchessahar, M. Ferri, M. Garandeau, L. Gremillet, V. Henot, E. Journot, J. C. Kieffer, I. Lantuejoul, L. Le Deroff, N. Lemos, C. Rousseaux, F. Scol, K. Ta Phuoc, W. Vaillant, B. Vauzour, M. Vranic, X. Davoine, F. Albert,Comments:Subjects: physics.plasm-phCreated: 2026-08-18; Updated: 2026-08-19; Datestamp: 2026-08-19
We report on the production of ultrahigh-charge RELATIVISTIC electron beams and the development of a LASER-wakefield acceleration platform at the LMJ facility. Making use of the kilojoule-class, sub-picosecond PETAL LASER pulse focused onto a supersonic helium gas JET, electron beams carrying a total charge beyond 1 $μ$C were generated, with energies up to $\sim$500 MeV. Given the ps-scale LASER pulse duration, an on-target intensity approaching $10^{19}~\mathrm{W/cm^2}$, and a plasma density reaching 2% of the critical density, electron energisation arises from a combination of self-modulated LASER wakefield acceleration (SMLWFA) and direct LASER acceleration (DLA). The resulting electron spectrum exhibits a Maxwellian-like distribution, characteristic of this mixed SMLWFA/DLA regime. The total energy carried by the electron beam is estimated to be up to 17 J, within a sub-ps duration. A broadband Joule-level photon beam was also produced by Bremsstrahlung, demonstrating the potential for future applications. Experimental results are supported by start-to-end numerical simulations, including 3-D particle-in-cell and Monte-Carlo particle transport calculations. These findings pave the way for applications requiring high-charge electron beams, including the generation of high-power secondary radiation or particle sources. The use of these beams to probe matter in high-energy density states driven by the nanosecond-duration LMJ beams represents another promising avenue.
[abstract 26 / 39] (score: 3) - Title: General RELATIVISTIC hydrodynamics of stellar tidal disruptions in Kerr spacetime: methods, validation, and first applicationsAuthors: Diego Calderón, Stephan Rosswog,Comments: Submitted to A&A. 12 pages, 5 figures, and 1 table (+ 8 pages, +5 figures, +1 table in Appendix)Subjects: astro-ph.HECreated: 2026-08-17; Updated: 2026-08-19; Datestamp: 2026-08-19
The disruption of a star by the tidal field of a super-massive BLACK HOLE may provide insights into dormant and otherwise hard-to-study galactic nuclei. State-of-the-art numerical tools have not converged on the importance of the strong RELATIVISTIC effects in the disruption of stars by potentially spinning BLACK HOLEs. We present a specialised numerical tool to perform global hydrodynamic simulations of stellar tidal disruptions in curved spacetimes. We quantify the role of impact strength and BLACK HOLE spin onto the stellar structures and mass fallback rates. We adapted the code SPHINCS_BSSN to perform General Relativistic Smoothed-Particle Hydrodynamics (GRSPH) simulations of stellar tidal disruptions in Kerr metric. We coupled the code with a Newtonian self-gravity module, and we added the option to use an entropy evolution formulation to handle numerically challenging situations. Besides describing the implementation and code validation, we present a set of 18 simulations of parabolic tidal disruptions of stellar polytropes to investigate the effect of impact strength and BLACK HOLE spin. We demonstrate that SPHINCS is capable of performing GRSPH simulations, reproducing benchmark tests to machine precision. Our stellar tidal disruption simulations show that the fallback rates agree with state-of-the-art modelling. Deep events result into structures where self-gravity plays no role, the mass fallback rates peak at lower values, and rise-to-peak timescales decrease with impact strength. In these cases the BLACK HOLE spin affects noticeable these quantities increasing (decrease) both fallback rate peak and rise-to-peak timescale for prograde (retrograde) spin. Last, fallback rates tend to decay with the characteristic $t^{-5/3}$ on long timescales. The results show that SPHINCS can simulate high-resolution stellar tidal disruptions in Kerr metric at a reasonable computational time.
[abstract 27 / 39] (score: 3) - Title: Revisiting neutrino event epochs for the BLAZAR PKS 0735+178 with TESSAuthors: Shubham Kishore, Alok C. Gupta, Debanjan Bose,Comments: Accepted for publication in ApJ, 13 pages, 6 figures, 1 tableSubjects: astro-ph.HECreated: 2026-08-18; Updated: 2026-08-19; Datestamp: 2026-08-19
We present here the results of the optical light curve variability analysis of the BLAZARs PKS 0735+178, in weeks-scale flare state, observed in three sectors with the Transiting Exoplanet Survey Satellite (TESS). The TESS observations in this study coincide with a well-known neutrino emission phase detected with four different neutrino observatories at multiple epochs in a narrow time window. We segmented the rising and decaying parts of the flare and individually analyzed their flux distribution, excess variance, variability timescale, and the power spectral density (PSD). The source displayed an elevated excess variance of ~25%, with a multi-modal flux distribution (coherent in the rising and distorted in the decaying phase). The variability timescale analysis highlights a much faster decay than the rising scale, and the PSDs depict a nominal change in the power spectral slope. We discuss a likely connection in the optical variations and the neutrino events, and briefly explain a possible physical scenario for the observed optical flux behavior in view of previously discovered radio-band results.
[abstract 28 / 39] (score: 3) - Title: The initial evolution of SN 2011dh: The importance of inhomogeneitiesAuthors: Claes-Ingvar Bjornsson,Comments: 30 pages, 6 figures, 1 appendix, accepted to ApJSubjects: astro-ph.HECreated: 2026-08-18; Updated: 2026-08-19; Datestamp: 2026-08-19
SN 2011dh is rather unique in that it offered detailed observations of the initial phase in the radio as well as optical regimes. This makes possible a comparison between models used to deduce properties of the outer envelope of the SUPERNOVA ejecta. It is shown that a consistent description suggests the forward shock to have started in the piston phase with constant velocity, and only later, around 50 days, transitioned to the standard model, which is independent of initial conditions. In addition, observations imply that the radio source is inhomogeneous with a covering factor of, approximately, 50%. It is emphasised that the deduced properties of the SYNCHROTRON source are very sensitive to the presence of inhomogeneities; for example, a covering factor of 50% increases the ratio of the energy densities of RELATIVISTIC electrons and MAGNETic field by several orders of magnitude as compared to a homogeneous source. The shallow density gradient in the envelope causes substantial deceleration of the forward shock. This is used to argue that the MAGNETic field strength scales inversely with radius rather than inversely with time; this is similar to SN 1993J. Attention is also drawn to the similarities between the flat spectra of compact, extragalatic radio sources and the evolution of radio SUPERNOVAe; e.g., the scaling of the MAGNETic field and the constant brightness temperature.
[abstract 29 / 39] (score: 3) - Title: Observations of Disrupted CME Material Falling Back Into the Low CoronaAuthors: Brian E. Wood, Jason E. Kooi,Comments: 28 pages, 15 figures, to appear in The Astrophysical JournalSubjects: astro-ph.SRCreated: 2026-08-18; Updated: 2026-08-19; Datestamp: 2026-08-19
We present an empirical study of a disrupted CME, parts of which fall back to the Sun, using observations from SOHO, STEREO-A, and SDO. At UT 18:00 on 2024 August 16, a slow CME is overtaken by a faster CME. A leg of the second CME carries part of the slower CME out with it, resulting in an unusually well-defined flux rope leg for this CME. This second CME is observed in radio by the VLA, with Faraday rotation measurements showing a clear MAGNETic flux rope signature. A strong response is also later seen when the radio-observed line of sight enters the CME leg enriched by material from the disrupted CME. Outside this leg, the rest of the disrupted CME simply disappears and is replaced by a large number of small JET-like downflows. We see clear evidence of this plasma falling back to the low corona in EUV images from SDO, roughly 6-17 hours after the CME is disrupted, with an inferred downward velocity of V=-30 km/s. There is a clear temperature dependence, with the downflows seen first in the 211 bandpass, followed successively by responses at 193, 171, and 304. The downflows are much slower than would be expected for a ballistic descent, so we model the downflows using a kinematic drag model. In the 304 bandpass, coronal rain activity is triggered by the downflowing CME material, suggesting that downflows from the upper corona could be contributing to coronal rain more generally.
[abstract 30 / 39] (score: 2) - Title: The Steep-spectrum Radio-loud AGN Luminosity Function and Its Implications for Black Hole Growth and Star FormationAuthors: Wenjie Wang, Zunli Yuan, B. Šlaus, Hongwei Yu, Yu Luo,Comments: 27 pages, 14 figures, Comments welcome!Subjects: astro-ph.GACreated: 2026-08-18; Updated: 2026-08-19; Datestamp: 2026-08-19
We study the cosmic evolution of radio-loud ACTIVE GALACTIC NUCLEi (AGNs) using a beaming-minimized sample of 4{,}555 steep-spectrum sources over $0
[abstract 31 / 39] (score: 2) - Title: Thermodynamics of Kerr-Bertotti-Robinson BLACK HOLEAuthors: Li Hu, Rong-Gen Cai, Shao-Jiang Wang,Comments: v1, 7 pages, no figure; v2, version accepted for publication in Physical Review D as a Letter; v3, to match the published versionSubjects: gr-qcCreated: 2026-08-18; Updated: 2026-08-19; Datestamp: 2026-08-19
We investigate the thermodynamic properties of the Kerr-Bertotti-Robinson BLACK HOLE, an exact Petrov type-D solution of Einstein-Maxwell theory describing a rotating BLACK HOLE immersed in an external electroMAGNETic field. While the conserved angular momentum and electric charge can be computed straightforwardly, the conserved mass cannot be obtained through standard integrability methods due to the nontrivial asymptotically uniform external electroMAGNETic field. To overcome this difficulty, we adopt the Christodoulou-Ruffini mass relation as a thermodynamic definition of the conserved mass and identify the associated generator, thereby fixing the ambiguity in defining this conserved mass and constructing the thermodynamic potentials. These thermodynamic quantities naturally satisfy the first law of black-hole thermodynamics as well as the Smarr formula.
[abstract 32 / 39] (score: 2) - Title: No model-independent evidence for a peak in binary BLACK HOLE spin (mis)alignmentsAuthors: Noah E. Wolfe, Salvatore Vitale, Michael Zevin,Comments: 8 + 13 pages, 4 + 9 figures; updated to match published versionSubjects: astro-ph.HE gr-qcCreated: 2026-08-18; Updated: 2026-08-19; Datestamp: 2026-08-19
The degree of black-hole spin-orbit misalignment ("tilts") in the astrophysical population could be a powerful diagnostic to distinguish between binary formation in isolation, in dynamical environments, or in hierarchical triples. However, robust population-level spin tilt measurements are complicated by model misspecification as well as numerical and Poisson variance, ultimately owing to poor single-event constraints on tilts. Motivated by reports of a possible peak in the spin tilt distribution, we analyze the fourth LIGO-Virgo-KAGRA gravitational-wave transient catalog to test for preferred spin orientations at different BLACK HOLE masses. We find that a peak in spin tilts is not statistically significant nor model independent. Since the data cannot be used to reliably identify subpopulations based on their spin tilt properties, we also consider a complementary approach: measuring the spin magnitude and tilt distributions at fixed mass scales. We find no confident correlation between mass and spin tilt, but we do confirm a confident correlation between spin magnitude and mass, corroborating recent analyses.
[abstract 33 / 39] (score: 2) - Title: Saturation Equations of State in Critical Gravitational Collapse: The Primordial Black Hole ThresholdAuthors: Benaoumeur Bakhti,Comments:Subjects: gr-qcCreated: 2026-08-18; Updated: 2026-08-19; Datestamp: 2026-08-19
The threshold and scaling laws of gravitational critical collapse depend sensitively on the matter equation of state. We investigate how these quantities are modified by a generic feature of dense matter that is absent from the radiation fluid commonly assumed in primordial BLACK HOLE (PBH) studies: pressure stiffening as a maximum density is approached. As an analytically tractable proxy, we adopt the closed-form equation of state of a single-occupancy lattice gas, \(p=-T\ln(1-ρ)\), which exhibits a density-dependent sound speed and a saturation density. Using general-RELATIVISTIC simulations of spherically symmetric collapse, we show that this nonlinear pressure feedback increases the PBH formation threshold by \(0.50\pm0.02\%\) relative to the radiation equation of state within the causal regime of the model. At the same time, the critical mass-scaling exponent remains \(γ=0.357\pm0.001\), consistent with the radiation-fluid value to within our numerical precision. This agreement reflects the fact that the lattice equation of state approaches the radiation fluid at low density and remains only a mild perturbation over the near-critical regime, rather than indicating a universal critical exponent. Our results provide a proof of principle that saturation-induced stiffening can stabilize gravitational collapse and shift the PBH threshold, while introducing a linear-response framework for assessing the impact of more realistic equations of state on primordial BLACK HOLE formation.
[abstract 34 / 39] (score: 2) - Title: Solver-in-the-loop training of deep learning closures for large-eddy simulation of turbulent premixed JET flamesAuthors: Priyesh Kakka, Jonathan F. MacArt,Comments:Subjects: physics.flu-dyn physics.comp-phCreated: 2026-08-17; Updated: 2026-08-19; Datestamp: 2026-08-19
Large-eddy simulation (LES) turbulence models often fail to capture the effects of chemical heat release and the resulting modulation of turbulence in premixed flames, underscoring the need for a framework that remains accurate across a broad range of physical regimes. We develop an augmented eddy-viscosity closure, based on deep neural networks calibrated jointly with the LES solution using adjoint-based optimization and differentiable programming, ensuring consistency with the governing partial differential equations (PDEs). Several objective functions and training methods are examined, and each model is assessed for its capability to interpolate and extrapolate across a wide range of Damköhler numbers. Relative to the Smagorinsky-model baseline, the best neural network model improves a posteriori errors in the LES primitive variables by 25-50% and in the resolved Reynolds stress and scalar flux by more than 60%. Crucially, the model generalizes across Damköhler number regimes, maintaining stability and accuracy even for out-of-sample conditions. These results demonstrate that PDE-consistent deep learning closures can recover both mean fields and resolved turbulence statistics in LES of turbulent premixed flames and can therefore provide a broadly applicable framework for turbulent combustion modeling.
[abstract 35 / 39] (score: 2) - Title: Confirmation of the Finch Flatter-Fainter Relation for the Quadruple Images of Lensed Point SourcesAuthors: Kaitlyn E. Roman, Paul L. Schechter,Comments: 3 pages. Authors' version, including Figure 1 at intended size and full resolutionSubjects: astro-ph.COCreated: 2026-08-17; Updated: 2026-08-19; Datestamp: 2026-08-19
Finch et al (2002) derived relations for the summed absolute magnifications of quadruply lensed images that vary inversely with flattening in two alternative isothermal gravitational potential models. However, they did not elaborate on the selection effects this "flatter-fainter'' relation induces in actual lensed systems. We test the relation against the Luhtaru et al (2021) sample of 39 quadruply lensed QUASARs (38 of which we model successfully), using predicted rather than observed magnifications to avoid the complication of microlensing. We found that the summed predicted magnification decreases by a factor of ten over the observed range of flattening.
[abstract 36 / 39] (score: 2) - Title: Surface gravity wave on a neutron star ocean trapped around a MAGNETic poleAuthors: Shin'ichirou Yoshida,Comments: 13 pages, 12 figuresSubjects: astro-ph.HECreated: 2026-08-18; Updated: 2026-08-19; Datestamp: 2026-08-19
A warm neutron star is expected to have a fluid "ocean" of heavy elements at its outermost part of the outer crust. As is on the terrestrial ocean, the neutron star ocean also has surface gravity waves. Around a MAGNETic pole of a star, the ocean may have a dip due to the strong MAGNETic pressure coming into play in the hydrostatic balance of the ocean. The dip enables the surface gravity wave to be trapped around the MAGNETic pole to form eigenmodes. The frequency of the mode is much lower than the dynamical frequency at the stellar surface, owing to the weak Coriolis force and the gradient in the ocean's depth that makes the eigenmodes present. We solve the equation of surface gravity waves in the local $β$-plane approximation and obtain the spectrum of discrete eigenmodes. We see that there are no axisymmetric modes and that the mode frequency decreases and asymptotes to zero as the number of nodes of the corresponding eigenfunction increases. This is reminiscent of the g-modes in the context of asteroseismology. Observations of X-ray binaries containing neutron stars reveal that some of the systems exhibit low-frequency quasi-periodic oscillations (QPOs) whose frequency is $1-10^3$mHz. We investigate whether the eigenmodes considered here may explain the low-frequency QPO spectrum. It is suggested that some of the QPOs in the system whose neutron star spins at the period less than $10$s may be consistent with the model. As far as the spin period is larger than $10$s, the eigenmode frequencies are too low to explain the observed QPOs.
[abstract 37 / 39] (score: 2) - Title: Sub-Second Collisionless Gyrokinetic Eigenvalue Solutions via Orbit-Invariant DecompositionAuthors: Anrui Luo, Jingyi Yu, Huasheng Xie, Jian Bao,Comments: 13 pages, 6 figuresSubjects: physics.plasm-phCreated: 2026-08-18; Updated: 2026-08-19; Datestamp: 2026-08-19
Fast analysis of microscopic drift-wave instabilities based on linear gyrokinetic simulation is desirable for modeling anomalous transport in fusion device. In this work, we present an orbit-invariant decomposition method for solving collisionless gyrokinetic eigenvalue problems. By discretizing velocity space along orbit invariants using particle energy and MAGNETic moment, the full eigenvalue matrix is separated into independent orbit blocks that couple with each other through the field equation, greatly reducing both matrix dimension and computational cost without sacrificing physics. Based on this method, we extend the MGK code [Phys.\ Plasmas 24, 072106 (2017)] with both CPU and GPU implementations, supporting collisionless electrostatic linear simulations in $s$--$α$ and Miller equilibrium model with kinetic. For kinetic ion temperature gradient (ITG) and trapped electron mode (TEM) eigenvalue problems, the solver reduces single-solution times to the 0.01--0.1s range---more than three orders of magnitude faster than CGYRO on the same hardware---enabling efficient large-scale parameter scans. The eigenfrequencies and mode structures are verified by comparing with CGYRO results. The method is generally adapt to to all collisionless gyrokinetic eigenvalue formulations and can be extended to fully electroMAGNETic simulations.
[abstract 38 / 39] (score: 2) - Title: EON-SII: Design of a transportable picosecond stellar intensity interferometer for compact-star astrophysicsAuthors: Thomas Schweizer, Josef Eder, Jürgen Besenrieder, Razmik Mirzoyan, Carina Haider, Olaf Reimann, Derek Strom, Roland Walter,Comments: 11 pages, 13 figures, to be published in Monthly Notices of the Royal Astronomical SocietySubjects: astro-ph.IMCreated: 2026-08-18; Updated: 2026-08-19; Datestamp: 2026-08-19
Stellar intensity interferometry (SII) measures correlations in photon-arrival fluctuations recorded by telescopes observing bright celestial sources. It can resolve angular scales far smaller than those accessible to a single optical telescope and is largely insensitive to atmospheric turbulence. After the first demonstration of SII on Sirius in 1956, Hanbury Brown and Twiss used the technique to measure the diameters of 32 stars. More recently, VERITAS, MAGIC, H.E.S.S., and CTAO's LST-1 have revived the method, although observations remain restricted to bright targets because of their optical design, optimized for gamma-ray astrophysics, rather than SII. We present EON-SII, the design and performance of a two-telescope intensity interferometer intended to extend the SII technique to compact targets at magnitudes of about V=8.5 up to V=10.7. Each transportable telescope has a 4-m diameter mirror, approximately 9m2 collecting area, an actively aligned 18-panel primary mirror, and Cassegrain optics specified to concentrate at least 90% of the light within 3 arcsec. A fibre-free spectrograph covers 400-550 nm at R~7000-8000 and is designed to provide of order 1000 statistically independent spectral channels.
[abstract 39 / 39] (score: 2) - Title: 3D simulations of MAGNETospheric accretion in T Tauri stars: I. Disk truncation, stellar torques, and application to observationsAuthors: George Pantolmos, Claudio Zanni, Jérôme Bouvier,Comments: 26 pages, 15 figures, accepted for publication in Astronomy & AstrophysicsSubjects: astro-ph.SRCreated: 2026-08-18; Updated: 2026-08-19; Datestamp: 2026-08-19
Young stars accrete material from their circumstellar disk through their MAGNETosphere while still contracting, two processes that impact their rotational evolution. We investigate stable and unstable accretion regimes (due to the interchange instability) and examine the associated stellar torques to assess the spin evolution of young stars. We perform 3D MHD simulations of disk accretion onto an inclined stellar dipole. We run 21 simulations with varying stellar stellar rotation rates, dipole field strengths and obliquities, and mass accretion rates. We find that stars with a ratio of truncation to corotation radius $R_t/R_{co} \gtrsim 0.80-0.85$ accrete via a stable regime, while accretion becomes unstable otherwise. Besides, our $R_t/R_{\ast}$ parametrization weakly depends on the mass accretion rate and the dipolar intensity, while strongly on the stellar rotation rate. We derive torque formulae for each flow component affecting the stellar rotation, i.e. accretion, MAGNETospheric ejections and stellar winds. Finally, we apply our results to a sample of young stars with measured MAGNETic fields, mass accretion rates, and rotational periods and find that most of them should currently accrete in an unstable regime and undergo spin-up torques. Our study comforts and expands upon previous results. Unstable accretion should lead to a net spin-up torque on the central star, while stable accretion can lead to stellar spin-down. When applying our truncation radius and torque prescriptions to observational data, we find that most young stars in our sample should be in a spin-up state. Thus, the angular momentum problem for young stars remains.
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