Current date: 2025-12-05
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Datestamp limit: 2025-12-05 (0 days ago)
Created/updated limit: 2025-11-28 (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: 236
Keyword score statistics
score 8 -- 1 abstracts
score 4 -- 2 abstracts
score 3 -- 4 abstracts
score 2 -- 7 abstracts
in total -- 14 abstracts
Articles that appeared on 2025-12-05
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[abstract 1 / 14] Wow! (score: 8)
- Title: Magnetic Field Amplification and Particle Acceleration in Weakly Magnetized Trans-RELATIVISTIC Electron-ion ShocksAuthors: Taiki Jikei, Daniel Groselj, Lorenzo Sironi,Comments: 16 pages, 13 figuresSubjects: astro-ph.HE physics.plasm-phCreated: 2025-12-02; Updated: 2025-12-05; Datestamp: 2025-12-05
We investigate the physics of quasi-parallel trans-RELATIVISTIC shocks propagating in weakly MAGNETized plasmas by means of long-duration two-dimensional particle-in-cell simulations. The structure of the shock precursor is shaped by a competition between the Bell instability and the Weibel instability. The Bell instability is dominant at relatively high MAGNETizations $(σ\gtrsim10^{-3})$, whereas the Weibel instability prevails at lower MAGNETizations $(σ\lesssim10^{-4})$. Bell-dominated shocks efficiently accelerate ions, converting a fraction $\varepsilon_{\mathrm{i}}\sim0.2$ of the upstream flow energy into downstream nonthermal ion energy. The maximum energy of nonthermal ions exhibits a Bohm scaling in time, as $E_{\max}\propto t$. A much smaller fraction $\varepsilon_{\mathrm{e}}\ll0.1$ of the upstream flow energy goes into downstream nonthermal electrons in the Bell-dominated regime. On the other hand, Weibel-dominated shocks efficiently generate both nonthermal ions and electrons with $\varepsilon_{\mathrm{i}}\sim\varepsilon_{\mathrm{e}}\sim0.1$, albeit with a slower scaling for the maximum energy, $E_{\mathrm{max}}\propto t^{1/2}$. Our results are applicable to a wide range of trans-RELATIVISTIC shocks, including the termination shocks of extragalactic JETs, the late stages of GAMMA-RAY BURST afterglows, and shocks in fast blue optical transients.
[abstract 2 / 14] Yes (score: 4) - Title: Long-living Equilibria in Kinetic Astrophysical Plasma TurbulenceAuthors: Mario Imbrogno, Claudio Meringolo, Sergio Servidio, Alejandro Cruz-Osorio, Benoît Cerutti, Francesco Pegoraro,Comments: 12 pages, 5 figures (Main Text), 3 figures (Appendices)Subjects: physics.plasm-ph astro-ph.HECreated: 2025-12-03; Updated: 2025-12-05; Datestamp: 2025-12-05
Turbulence in classical fluids is characterized by persistent structures that emerge from the chaotic landscape. We investigate the analogous process in fully kinetic plasma turbulence by using high-resolution, direct numerical simulations in two spatial dimensions. We observe the formation of long-living vortices with a profile typical of macroscopic, MAGNETically dominated force-free states. Inspired by the Harris pinch model for inhomogeneous equilibria, we describe these metastable solutions with a self-consistent kinetic model in a cylindrical coordinate system centered on a representative vortex, starting from an explicit form of the particle velocity distribution function. Such new equilibria can be simplified to a Gold-Hoyle solution of the modified force-free state. Turbulence is mediated by the long-living structures, accompanied by transients in which such vortices merge and form self-similarly new metastable equilibria. This process can be relevant to the comprehension of various astrophysical phenomena, going from the formation of plasmoids in the vicinity of massive compact objects to the emergence of coherent structures in the heliosphere.
[abstract 3 / 14] Yes (score: 4) - Title: Solar Cycle Variation of Sustained Gamma Ray Emission from the SunAuthors: Nat Gopalswamy, Pertti Mäkelä, Seiji Yashiro, Sachiko Akiyama, Hong Xie, G. Sindhuja,Comments: 27 pages, 6 figures, 3 tables, Submitted to Solr PhysicsSubjects: astro-ph.HE astro-ph.SRCreated: 2025-12-04; Updated: 2025-12-05; Datestamp: 2025-12-05
We investigated the occurrence rate of the sustained gamma ray emission (SGRE) events from the Sun using FERMI Large Area Telescope (LAT) data covering solar cycle (SC) 24 and the rising and maximum phases of SC 25. Due to a solar array drive assembly malfunction starting in March 2018, only small number (15) of SGRE events were observed during SC 25. Over the first 61 months, the average sunspot number (SSN) increased from 56.9 in SC 24 to 79.0 in SC 25. Fast and wide (FW) CMEs and decameter-hectometric (DH) type II bursts also increased significantly in SC 25 by 29% and 33%, respectively when normalized to SSN. Therefore, the increase in solar activity should result in a higher number of SGREs in SC 25. We estimated the number of SGREs in SC 25 using three methods. (i) If the SGRE number varies commensurate FW CMEs and DH type II bursts, SC 25 should have 45-47 SGRE events. (ii) In SC 24, ~17% of FW CMEs and 25% of DH type II bursts were associated with SGRE events. At this rate, SC 25 should have 46 SGRE events. (iii) Since SGRE events are invariably associated with >100 keV hard X-ray (HXR) bursts, we identified DH type II bursts associated with >100 keV HXR bursts from FERMI gamma ray burst monitor (GBM) during LAT data gaps. Based on our finding that SGRE events in SCs 24 and 25 were all associated with HXR bursts of duration > ~5 min, we found only 27 of the 79 LAT-gap type II bursts had >100 keV HXR bursts with duration > ~5 min. These DH type II bursts are likely to indicate SGRE, bringing the total number of SGRE events to 42 (15 observed + 27 inferred). Thus, the three methods provide similar estimates of the number of SGRE events in SC 25. We, therefore, conclude that that SC 25 is stronger than SC 24 based on the estimated number SGRE events. Halo CMEs, ground level enhancement (GLE) events, and intense geoMAGNETic storms are also consistent with a stronger SC 25.
[abstract 4 / 14] (score: 3) - Title: Testing new-physics scenarios with the combined LHAASO and Carpet-3 fluence spectrum of GRB 221009A: axion-like particles and Lorentz-invariance violationAuthors: P. S. Satunin, S. V. Troitsky,Comments: 7 pages, 5 figures, JETP Letters style. V2: minor clarifications, results unchanged, accepted by JETP LettersSubjects: astro-ph.HE hep-phCreated: 2025-12-04; Updated: 2025-12-05; Datestamp: 2025-12-05
From GAMMA-RAY BURST (GRB) 221009A, very high-energy photons were detected: >10 TeV with LHAASO and >100 TeV with Carpet-3. Such energetic photons are expected to be absorbed via electron-positron pair production on their way to the Earth. Their observation might be explained by new physics, including Lorentz invariance violation (LIV) or photon mixing with axion-like particles (ALPs). Here, we construct a joint fluence spectrum by combining flux measurements from both experiments, and fit it under these hypotheses. While LIV can account for the Carpet-3 observation, it provides only a modest improvement over standard physics in the overall fit and requires parameters excluded by other constraints. ALP mixing improves the description of both LHAASO and Carpet-3 data, yielding a substantial enhancement in fit quality for a specific region of the ALP parameter space.
[abstract 5 / 14] (score: 3) - Title: JWST Confirmation of a Runaway Supermassive Black Hole via its Supersonic Bow ShockAuthors: Pieter van Dokkum, Connor Jennings, Imad Pasha, Charlie Conroy, Ish Kaul, Roberto Abraham, Shany Danieli, Aaron J. Romanowsky, Grant Tremblay,Comments: Submitted to ApJ Letters. The single most important new observation is the 600 km/s gradient in the position-velocity diagram, shown in Fig. 7. The discovery paper (van Dokkum et al. 2023) was right about the key interpretation but had quite a few of the details wrong. This is reviewed in section 6.5Subjects: astro-ph.GA astro-ph.CO astro-ph.HECreated: 2025-12-03; Updated: 2025-12-05; Datestamp: 2025-12-05
We present JWST/NIRSpec IFU observations of a candidate runaway supermassive BLACK HOLE at the tip of a 62 kpc-long linear feature at z=0.96. The JWST data show a sharp kinematic discontinuity at the tip, with a radial velocity change of $\approx 600$ km/s across 0.1'' (1 kpc). The velocity gradient, together with the projected post-shock flow velocity of $\approx 300$ km/s, is well described by a simple shock-compression model of a supersonic object, with a velocity of $v_{BH} = 954^{+110}_{-126}$ km/s and an inclination $i=29^{+6}_{-3}$ deg. The previously puzzling kinematics along the linear feature, with the observed radial velocity decreasing from $\approx 300$ km/s near the tip to $\approx 100$ km/s closer to the former host galaxy, are naturally explained as gradual downstream mixing of shocked gas with the circumgalactic medium through turbulent entrainment. The runaway BLACK HOLE interpretation is further supported by the morphology of the gas at the tip of the wake and an analysis of the [OIII]/H$α$, [NII]/H$α$, [SII]/H$α$, and [SIII]/[SII] line ratios. The line ratios are consistent with fast radiative shocks and rapid cooling, with best-fit shock velocities that are in good agreement with expectations from the BLACK HOLE velocity and the shock geometry. Energy conservation over the lifetime of the wake suggests a SMBH mass of $M_{BH} \gtrsim 10^7$ M$_{\odot}$. These results confirm that the wake is powered by a supersonic runaway supermassive BLACK HOLE, a long-predicted consequence of gravitational-wave recoil or multi-body ejection from galactic nuclei.
[abstract 6 / 14] (score: 3) - Title: The impact of strong feedback on galaxy group scaling relationsAuthors: D. Eckert, R. Seppi, J. Braspenning, A. Finoguenov, F. Gastaldello, L. Lovisari, E. O'Sullivan, S. Ettori, B. D. Oppenheimer, M. A. Bourne, D. -W. Kim, M. Sun, H. Khalil, G. Gozaliasl, Y. E. Bahar, V. Ghirardini, W. Cui, K. Kolokythas, S. McGee,Comments: Submitted to A&A LettersSubjects: astro-ph.CO astro-ph.GA astro-ph.HECreated: 2025-12-03; Updated: 2025-12-05; Datestamp: 2025-12-05
Feedback from active supermassive BLACK HOLEs alters the distribution of matter in the Universe by injecting energy in the neighbouring hot gaseous medium, which leads to ejection of gas from the halos of galaxy groups and massive galaxies. Recent cosmological simulations such as FLAMINGO calibrate their feedback model on the baryon fractions of galaxy groups to tune the efficiency of gas ejection. However, recent observational constraints from optically selected groups and the kinetic Sunyaev-Zel'dovich effect yield lower baryon fractions than previous studies, which indicates that feedback may be more ejective than previously thought. Here we show that models involving highly ejective feedback are inconsistent with the scaling relations of local galaxy groups in the mass range $10^{13}-10^{14}M_\odot$. We study the X-ray luminosity-temperature relation in a sample of 44 galaxy groups with high-quality XMM-Newton observations. We show that highly ejective models under-predict the luminosity of galaxy groups at fixed mass at high significance ($5.7σ$). This conclusion is robust against selection effects and is obtained from directly measurable and minimally correlated quantities. We point out that turning observable quantities into gas fraction estimates is challenging, especially in the context of stacking large samples of heterogeneous systems. We argue that calibrating feedback models on baryon fractions is prone to systematic uncertainties and that observable scaling relations are better suited for this task.
[abstract 7 / 14] (score: 3) - Title: A distance measurement for BLAZAR TXS 0506+056 using its radio variability and very long baseline imagesAuthors: Chanwoo Song, Sang-Sung Lee, Sincheol Kang, Whee Yeon Cheong,Comments: 16 pages, 9 figures, Accepted for publication in A&ASubjects: astro-ph.GACreated: 2025-12-03; Updated: 2025-12-05; Datestamp: 2025-12-05
We present the results of constraining the angular diameter distance to BLAZAR TXS 0506+056. We used data obtained with the 15 GHz VLBA in MJD 54838-60262 and data from the 15 GHz OVRO 40 m single dish telescope in MJD 54474-59023. We used a variability timescale and a causality argument of a linear size to measure the angular diameter distance to the source. To constrain the Doppler factor, we applied the relation between the rest-frame brightness temperature of the emission region and the observed brightness temperature. To calculate the observed brightness temperature, the angular size and flux density variation of the emission region are required. The angular size of the emission region (i.e., the VLBA core) was obtained from a FWHM, which is a circular Gaussian model-fitting parameter that ranges from 0.048-0.228 mas, and its uncertainty is determined to be 1.8-13 %. Using the OVRO SD light curve, we obtained a variability timescale of $128.0_{-0.3}^{+0.2}$ days and a peak flux density of $1.750_{-0.104}^{+0.015}$ Jy for the largest flare that peaked on MJD $58921.7_{-5.5}^{+2.6}$. We assumed a disk brightness geometry, equipartition brightness temperature ($5\times10^{10}$ K), and perfect radius. Using the VLBA core sizes obtained near the flare peaks, we found consistent distance measurement results with the $Λ$CDM model within 1$σ$ uncertainties. We suggest that the best distance from the source is $941_{-64}^{+59}$ Mpc, which is comparable with the $Λ$CDM distance of $948.2\pm13.5$ Mpc. The distance measurement should indeed be taken at the peak of a flare. We found that the decomposed timescale allowed us to obtain consistent distances with the $Λ$CDM. We strongly suggest to decompose light curves when the variability timescales are to be obtained properly.
[abstract 8 / 14] (score: 2) - Title: What is the most massive gravitational-wave source?Authors: Ilya Mandel,Comments: updated version, as accepted for publication in Astrophysical Journal LettersSubjects: astro-ph.HE astro-ph.SR gr-qcCreated: 2025-12-04; Updated: 2025-12-05; Datestamp: 2025-12-05
In the presence of significant measurement uncertainties, the events which appear to be the most extreme are very likely to be those exhibiting the greatest statistical fluctuations. It is therefore particularly important to exercise care when interpreting such events and to use the entire observed population for context. Here, I attempt to pedagogically illustrate this using the example of the most massive binary BLACK HOLE so far detected in gravitational-wave data, GW231123. I argue that its total mass may be significantly lower than $238^{+28}_{-49}$ solar masses as reported by Abac et al. (2025a). The maximum total binary BLACK HOLE mass from an analysis of the entire detected population is below 170 solar masses if the same priors that are used for individual event analyses in the GWTC catalogs, including for the analysis of GW231123, are applied to the population as a whole. However, this value is very sensitive to assumptions about the population distribution.
[abstract 9 / 14] (score: 2) - Title: One-shot acceleration of transient PDE solvers via online-learned preconditionersAuthors: Mikhail Khodak, Min Ki Jung, Brian Wynne, Edmond Chow, Egemen Kolemen,Comments: code available at https://github.com/mkhodak/PCGBanditSubjects: physics.comp-ph cs.LG cs.NA math.NA stat.MLCreated: 2025-12-03; Updated: 2025-12-05; Datestamp: 2025-12-05
Data-driven acceleration of scientific computing workflows has been a high-profile aim of machine learning (ML) for science, with numerical simulation of transient partial differential equations (PDEs) being one of the main applications. The focus thus far has been on methods that require classical simulations to train, which when combined with the data-hungriness and optimization challenges of neural networks has caused difficulties in demonstrating a convincing advantage against strong classical baselines. We consider an alternative paradigm in which the learner uses a classical solver's own data to accelerate it, enabling a one-shot speedup of the simulation. Concretely, since transient PDEs often require solving a sequence of related linear systems, the feedback from repeated calls to a linear solver such as preconditioned conjugate gradient (PCG) can be used by a bandit algorithm to online-learn an adaptive sequence of solver configurations (e.g. preconditioners). The method we develop, PCGBandit, is implemented directly on top of the popular open source software OpenFOAM, which we use to show its effectiveness on a set of fluid and MAGNETohydrodynamics (MHD) problems.
[abstract 10 / 14] (score: 2) - Title: Rotating twisted MAGNETosphere of MAGNETars: approximate analytical solutionsAuthors: H. Tong, L. Chen,Comments: 8 pages, accepted in MNRASSubjects: astro-ph.HECreated: 2025-12-04; Updated: 2025-12-05; Datestamp: 2025-12-05
An approximate analytical solution for the rotating twisted MAGNETosphere of MAGNETars is presented. The poloidal flux is approximated by the self-similar twisted dipole field. The toroidal field is obtained by the minimum torque model. Under this approximation, it is found that: (1) The Y-point radius decreases with the increase of twist of the MAGNETic field. (2) The polar cap is larger for larger twist. (3) The particle outflow luminosity is larger for larger twist. (4) The maximum acceleration potential, pulse width of MAGNETar radio emission both increase with the twist. (5) For an untwisting MAGNETosphere, the physical properties evolve toward that of the normal pulsars. The above findings are consistent with previous analytical and numerical results. The larger polar cap may correspond to the hot spot during MAGNETar outburst. In general, a rotating twisted MAGNETosphere has larger open field line regions. The radio emission of MAGNETars and fast radio bursts may both originate in the larger and evolving open field line regions of MAGNETars.
[abstract 11 / 14] (score: 2) - Title: FPGA-Accelerated Real-Time Beam Emission Spectroscopy Diagnostics at DIII-D Using the SLAC Neural Network Library for ML InferenceAuthors: Abhilasha Dave, James Russell, Mudit Mishra, Larry Ruckman, Keith Erickson, SangKyeun Kim, Semin Joung, Jalal Butt, Ryan Herbst, Ryan Coffee, David Smith, Egemen Kolemen,Comments: Needs internal review process on our endSubjects: physics.plasm-phCreated: 2025-12-03; Updated: 2025-12-05; Datestamp: 2025-12-05
Achieving reliable real-time control of tokamak plasmas is essential for sustaining high-performance operation in next-generation fusion reactors. A major challenge is the accurate and timely prediction of edge-localized modes (ELMs), especially in high-confinement regimes such as wide-pedestal quiescent H-mode. We present a hardware-accelerated machine learning (ML) inference system integrated into the RTSTAB processing node of the DIII-D real-time diagnostic and control infrastructure. The system uses an AMD/Xilinx KCU1500 FPGA to enable ultra low latency plasma state classification and ELM forecasting. Input features come from real-time Beam Emission Spectroscopy (BES), and the ML model is implemented as a dense neural network using the SLAC Neural Network Library (SNL). A key capability is SNL dynamic parameter loading, which allows on-the-fly updates of neural network weights and biases without hardware resynthesis. This enables multiple classification tasks on a single FPGA design and supports adaptive control strategies that respond to evolving plasma conditions. By decoupling inference from fixed-weight configurations, the system supports continuous model refinement and seamless task switching during live operation. The SNL-based inference engine is fully integrated with the FPGA in the DIII-D RTSTAB Plasma Control System (PCS), improving ELM avoidance, confinement, and operational stability. These results show the feasibility of embedding dynamically reconfigurable FPGA-based ML inference into real-time fusion diagnostic pipelines, providing a scalable and resilient path toward intelligent and autonomous plasma control in future MAGNETic confinement fusion devices.
[abstract 12 / 14] (score: 2) - Title: Statistical and Temporal Analysis of Multi-component Burst-clusters from the Repeating FRB 20190520BAuthors: Jia-heng Zhang, Chen-Hui Niu, Yu-hao Zhu, Di Li, Yu Wang, Wei-yang Wang, Yi Feng, Xin-ming Li, Jia-rui Niu, Pei Wang, Yun-wei Yu, Yong-kun Zhang, Xiao-ping Zheng,Comments:Subjects: astro-ph.HECreated: 2025-12-04; Updated: 2025-12-05; Datestamp: 2025-12-05
Fast Radio Bursts (FRBs) are bright, millisecond-duration extragalactic radio transients that probe extreme astrophysical environments. Many FRBs exhibit multi-component structures, which encode information about their emission mechanisms or progenitor systems and thus provide important clues to their origins. In this work, we systematically analyze the burst morphology of FRB 20190520B and compare component distributions across four active FRBs observed with FAST: FRB 20121102A, FRB 20190520B, FRB 20201124A, and FRB 20240114A. We find that multi-component burst-clusters show spectral properties similar to single-peak bursts, and no periodicity is detected in their temporal behavior. The component-count distributions follow a power law, revealing scale-free behavior consistent with self-organized criticality (SOC) processes. Multi-component clusters account for 12-30% of all detected bursts, regardless of source activity, providing new insights into burst-to-burst variability and the physical processes driving FRB emission.
[abstract 13 / 14] (score: 2) - Title: A Black-Hole Envelope Interpretation for Cosmological Demographics of Little Red DotsAuthors: Hiroya Umeda, Kohei Inayoshi, Yuichi Harikane, Kohta Murase,Comments: Submitted to ApJL. Comments are welcomeSubjects: astro-ph.GACreated: 2025-12-03; Updated: 2025-12-05; Datestamp: 2025-12-05
Little red dots (LRDs) newly discovered with JWST are ACTIVE GALACTIC NUCLEi (AGN) that may represent BLACK HOLE (BH) growth at the earliest cosmic epochs. These sources show puzzling features unlike typical AGNs, including red optical continua, weak hot-dust emission, and a lack of detectable X-rays. Previously, LRDs have often been interpreted as dust-reddened AGNs, leading to severe inconsistencies with the luminosity and BH mass densities inferred for previously known AGNs over $0
[abstract 14 / 14] (score: 2) - Title: Asymptotic constraints for 1D planar grey photon diffusion from linear transport with special-RELATIVISTIC effectsAuthors: Ryan T. Wollaeger, Jim E. Morel, Kendra P. Long, Mathew A. Cleveland, Robert B. Lowrie,Comments: 31 pages, 5 figures, 1 table. Submitted to the Journal of Quantitative Spectroscopy and Radiative Transfer (JQSRT) on 12/2/2025Subjects: astro-ph.HECreated: 2025-12-04; Updated: 2025-12-05; Datestamp: 2025-12-05
We derive a grey linear diffusion equation for photons with respect to inertial (or lab-frame) space and time, using asymptotic analysis in 1D planar geometry. The solution of the equation is the comoving radiation energy density. Our analysis does not make use of assumptions about the magnitude of velocity; instead we derive an asymptotic scaling in the lab frame such that we avoid apparent non-physical pathologies that are encountered with the standard static-matter scaling. We permit the photon direction to be continuous (as opposed to constraining the analysis to discrete ordinates). The result is a drift-diffusion equation in the lab frame for comoving radiation energy density, with an adiabatic term that matches the standard semi-RELATIVISTIC diffusion equation. Following a recent study for discrete directions, this equation reduces to a pure advection equation as the velocity approaches the speed of light. We perform preliminary numerical experiments comparing solutions to RELATIVISTIC lab-frame Monte Carlo transport and to the well-known semi-RELATIVISTIC diffusion equation.
arXiv:2512.03169 [pdf, ps, other]
arXiv:2408.02656 [pdf, ps, other]
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