Current date: 2026-07-30
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Number of records retrieved: 684
Keyword score statistics
score 11 -- 1 abstracts
score 10 -- 1 abstracts
score 8 -- 1 abstracts
score 7 -- 2 abstracts
score 6 -- 2 abstracts
score 5 -- 4 abstracts
score 4 -- 5 abstracts
score 3 -- 6 abstracts
score 2 -- 21 abstracts
in total -- 43 abstracts
Articles that appeared on 2026-07-30
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[abstract 1 / 43] Wow! (score: 11)
- Title: Spectroscopic Analysis of FERMI-detected Blazars using SDSS-VAuthors: Mohammed Iddrisu Nlowie, James Aird, Eli Kasai, Amy L. Rankine, Paloma Guetzoyan, Scott Anderson, Catarina Aydar, William N. Brandt, Joel R. Brownstein, Xinyu Dai, Lorena Hernández-García, Paola Rodríguez Hidalgo, Pranavi Hiremath, Anton Koekemoer, Andrea Merloni, Sean Morrison, Mara Salvato, Donald P. Schneider, Axel Schwope, Benny Trakhtenbrot,Comments: 34 pages, 17 figures plus appendices. Submitted to MNRAS. Catalogue available as SDSS DR20 Value-Added Catalogue https://www.sdss.org/dr20/data_access/value-added-catalogs/?vac_id=10034 Accompanied visualization python package tool https://github.com/minlowie/Blazar-Analysis-PipelineSubjects: astro-ph.HECreated: 2026-07-28; Updated: 2026-07-30; Datestamp: 2026-07-30
The automated spectroscopic pipeline of the Sloan Digital Sky Survey (SDSS) systematically assigns Galactic star, galaxy, or typical QUASAR classifications to JET-dominated BLAZARs, owing to the absence of a non-thermal JET continuum component in its template library. In this study, we present a new, physically motivated, multi-component spectral fitting pipeline that we apply to 746 optical counterparts of FERMI/4FGL-DR4 $γ$-ray sources in the SDSS-V Data Release 20 spectroscopic database, yielding 707 well-fitted BLAZAR candidates dominated by Power-law+Galaxy (59.4%), Power-law+Lines (22.6%), and Power-law+QSO (15.0%) model families. Independent WISE infrared (IR) photometry confirms that 96.6% of the 88 sources originally misclassified as Galactic stars by SDSS fall within the canonical BLAZAR region, with 90.9% reclassified as BL Lacertae object (BL Lac) candidates, demonstrating the success of our new pipeline. The new classification scheme naturally recovers the known cosmological separation between BL Lac and Flat Spectrum Radio Quasar (FSRQ) candidates and a separation of approximately one order of magnitude in median $γ$-ray luminosity. We compare our redshift estimates to a validation sample of 111 sources in the Third FERMI-LAT Catalogue of High-Energy Sources (3FHL), finding a 10.4% reduction in catastrophic failures ($η= 0.387$ vs 0.432) over the SDSS pipeline. The equivalent width analysis validates the traditional |EW| = 5 Ang classification boundary at the population level (BL Lac: 4.47 $\pm$ 0.15 Ang; FSRQ: 22.86 $\pm$ 0.86 Ang), although 49.5% of individual BL Lac candidates exceed this threshold and 51.4% show simultaneous emission and absorption features. This hybrid population challenges the traditional binary BLAZAR classification and points towards a more physically continuous description of BLAZAR properties.
[abstract 2 / 43] Wow! (score: 10) - Title: The ultra-fast afterglow of GRB 260226AAuthors: Biswajit Banerjee, Alessio Mei, Annarita Ierardi, Samanta Macera, Gor Oganesyan, Shraddha Mohnani, Elias Kammoun, Pawan Tiwari, Stefano Ascenzi, Samuele Ronchini, Ansh Chopra, Alessio Ludovico De Santis, Stefano Covino, Paolo D'Avanzo, Andrea Melandri, Silvia Piranomonte,Comments: SubmittedSubjects: astro-ph.HECreated: 2026-07-28; Updated: 2026-07-30; Datestamp: 2026-07-30
Long-duration GAMMA-RAY BURSTs are typically powered by RELATIVISTIC JETs launched after the core collapse of some rapidly rotating massive stars. Internal dissipation releases part of the JET energy as highly variable MeV prompt emission, while the remaining kinetic energy drives an external shock into the surrounding medium and produces the so-called afterglow. During the first minutes of the afterglow, the unsteady JET transfers energy to the external shock. The early afterglow emission in MeV-GeV energies is rarely observed because the emergence of afterglow can be overshined by the prompt emission. Here we report exceptional observations of GRB 260226A with the FERMI Large Area Telescope, which recorded the largest number of photons above 100 MeV from a GAMMA-RAY BURST. These data allow us to reconstruct the evolution of the bolometric flux of the afterglow from its emergence during the prompt emission phase with unprecedented detail. The afterglow component peaks near 50 MeV and fades rapidly, first as t$^{-1.5}$ and then transiting to an ultra-fast t$^{-2.8}$ decay after about one minute. This behavior cannot be explained by standard SYNCHROTRON emission from a blast wave propagating into a cold medium. We interpret it as external inverse Compton radiation from freshly heated electrons cooling on prompt photons in a dense, pair-loaded stellar wind. GRB 260226A therefore shows that MeV-GeV observations can directly reveal the formation of the external shock and the massive-star environment is significantly reshaped by the prompt emission.
[abstract 3 / 43] Wow! (score: 8) - Title: Multimessenger Signatures of Tilted, Self-Gravitating, Black Hole DisksAuthors: Milton Ruiz, Antonios Tsokaros, Stuart L. Shapiro,Comments: 9 pages, 11 figuresSubjects: gr-qc astro-ph.HECreated: 2026-07-28; Updated: 2026-07-30; Datestamp: 2026-07-30
We perform fully RELATIVISTIC GRMHD simulations of MAGNETized, self-gravitating BLACK HOLE-disk (BHD) systems in which the BLACK HOLE spin is misaligned with the disk angular momentum. Massive disks (disk to BH mass ratios of $16-28\%$) around rapidly rotating BLACK HOLEs ($χ\lesssim 0.97$) develop a nonaxisymmetric instability for tilt angles from $0^\circ$ to $180^\circ$. Magnetic stresses damp, but do not completely suppress, the nonaxisymmetric instability, and corresponding gravitational wave (GW) emission, in aligned systems, while they enhance it in antialigned BHDs: MRI-driven turbulence enhances angular momentum transport and accelerates nonlinear instability evolution in misaligned configurations. All models launch MAGNETically driven JETs consistent with the Blandford-Znajek (BZ) mechanism, with collimation depending on spin orientation. The GWs reflect strong nonaxisymmetric structure from a persistent $m=1$ mode. The coupling between fast MRI and the slower nonaxisymmetric instability growth governs the outcome, with tilt controlling how MRI modifies the global mode. These simulations provide the first self-consistent GRMHD treatment of tilted, self-gravitating BHD systems and support their role as multimessenger sources.
[abstract 4 / 43] Wow! (score: 7) - Title: On the double-adiabatic equations in the RELATIVISTIC regimeAuthors: Francisco Ley, Aaron Tran, Ellen G. Zweibel,Comments: Accepted at Journal of Plasma Physics, typos corrected; 30 pages, 8 figuresSubjects: physics.plasm-ph astro-ph.HECreated: 2026-07-28; Updated: 2026-07-30; Datestamp: 2026-07-30
We revisit the double adiabatic evolution equations and extend them to the RELATIVISTIC and ultraRELATIVISTIC regimes. We analytically solve the RELATIVISTIC, time-dependent drift kinetic equation for a homogeneous, MAGNETized, collisionless plasma and obtain a solution explicitly dependent on the MAGNETic field and density variations. In the case of an initial RELATIVISTIC Maxwellian distribution, a natural extension to an anisotropic Maxwell-Jüttner is obtained. We calculate the moments of this time-dependent solution and obtain analytical expressions for the evolution of the perpendicular and parallel pressures in the ultraRELATIVISTIC case. We numerically solve the moment equations in the RELATIVISTIC case and obtain general expressions for the double-adiabatic equations in this regime. We confirm our results using fully kinetic particle-in-cell simulations of shearing and compressing boxes. Our findings can be readily applied to RELATIVISTIC species including cosmic-rays and electron-positron pairs, present in astrophysical plasmas like pulsar wind nebulae, astrophysical JETs, BLACK HOLE accretion flows, and Van Allen radiation belts.
[abstract 5 / 43] Wow! (score: 7) - Title: Locating the Production Sites of High-Energy Neutrinos in Blazar JetsAuthors: Rui Xue, Yoshiyuki Inoue, Ze-Rui Wang, Neng-Hui Liao, Dingrong Xiong,Comments: 22 pages, 6 figures, 5 tables, accepted by ApJS. Comments welcome!Subjects: astro-ph.HECreated: 2026-07-29; Updated: 2026-07-30; Datestamp: 2026-07-30
The production sites of high-energy neutrinos in BLAZAR JETs remain poorly constrained. In this work, we investigate the physical conditions required for efficient neutrino production by using radio-constrained JET properties to evaluate the radial evolution of the external-to-MAGNETic energy density ratio (Compton dominance $Y$). We identify $Y \gg 1$ as the key physical condition for efficient neutrino production, as it simultaneously enhances photohadronic interactions and suppresses SYNCHROTRON radiation from secondary pairs, thereby avoiding an excess of hard X-ray emission. We find that such large values of $Y$ are most readily achieved near or within the broad-line region. This large-$Y$ condition is generally incompatible with reproducing the observed broadband spectral energy distribution within a single emission region, naturally indicating that the neutrino-emitting region is physically distinct from the dominant electroMAGNETic emission zone. We further show that such a scenario can be realized either if the JET completes its acceleration within sub-parsec scales or if the bulk Lorentz factor is intrinsically large, both of which appear uncommon based on current observations. These results offer a physically motivated framework for identifying neutrino production sites, provide a natural explanation for the rarity of BLAZAR--neutrino associations, and underscore the importance of constraining JET property at sub-parsec scales in the search for neutrino-emitting BLAZARs.
[abstract 6 / 43] Yes (score: 6) - Title: Kilonova and progenitor properties of merger-driven GAMMA-RAY BURSTsAuthors: P. Singh, G. Stratta, A. Rossi, P. T. H. Pang, M. Bulla, F. Ragosta, A. De Rosa, D. A. Kann, F. Cogato,Comments: 31 pages, 27 figuresSubjects: astro-ph.HECreated: 2026-07-29; Updated: 2026-07-30; Datestamp: 2026-07-30
Gamma-Ray Burst (GRB) prompt and afterglow emission, as well as a kilonova (KN), are the expected electroMAGNETic (EM) counterparts of Binary Neutron Star (BNS) and Neutron Star -- Black Hole (NSBH) mergers. We aim to infer the KN ejecta parameters and the progenitor properties by modeling merger-driven GRBs with a claim of KN, good data and robust redshift measurement. We model the afterglow and KN, and perform a Bayesian analysis, within the Nuclear physics and Multi-Messenger Astrophysics (NMMA) framework. The KN emission is modeled with the radiative transfer code POSSIS and for afterglow we use the afterglowpy library. In contrast to previous approaches, our methodology simultaneously models both afterglow and KN. We find that all GRBs in our sample have a KN, but we were unable to confirm or exclude its presence in GRB 150101B. A BNS progenitor is favored for GRB 160821B, GRB 170817A/AT2017gfo, GRB 211211A, and GRB 230307A. For GRB 150101B and GRB 191019A, we obtain a slight preference for NSBH scenario, while a BNS is also viable. For KN emission, we find that the median wind mass $\langle M_{\rm wind}\rangle=0.027^{+0.046}_{-0.019}$ $M_{\odot}$ is larger than the dynamical $\langle M_{\rm dyn}\rangle = 0.012^{+0.007}_{-0.006}$ $M_{\odot}$. We find that $M_{\rm wind}$ and the beaming corrected kinetic energy of the JET can be attributed as $log(M_{\rm wind})=-20.23+0.38\,log(E_{0,J})$. We confirm the results of numerical simulation that $\tildeΛ$ increases with decrease in $\mathcal{M}_{\rm \,Chirp}$. Our work shows that EM modeling can be effective for probing the progenitors, and for the first time presents the progenitor properties of a sizable sample of merger-driven GRBs.
[abstract 7 / 43] Yes (score: 6) - Title: Radio Jet Properties of the Flaring Gamma-Ray Blazar PKS 0346-27Authors: Máté Krezinger, Sándor Frey, Krisztina É. Gabányi,Comments: 19 pages, 4 figures, accepted for publication in the journal AstronomySubjects: astro-ph.GACreated: 2026-07-27; Updated: 2026-07-30; Datestamp: 2026-07-30
The BLAZAR PKS 0346-27 at redshift z=0.991 is among the most distant extragalactic sources detected in very high energy gamma-rays. It underwent a major flare reaching TeV energies in November 2021. Recent modelling of its spectral energy distribution favoured a single-zone proton--SYNCHROTRON-dominated hadronic model with bulk Lorentz factor Gamma=10 over a single-zone leptonic JET model with much higher Gamma. Here we analyse archival radio data to give independent estimates of the JET bulk Lorentz factor. We present high-resolution radio imaging and brightness distribution modelling, as well as flare detection in long-term radio flux density monitoring data, and obtain Gamma<~10 values. This lends support to the hadronic model proposed for the PKS 0346-27 JET. Our results highlight the importance of long-term, very long baseline interferometry and total flux density monitoring in studying BLAZAR JETs.
[abstract 8 / 43] Yes (score: 5) - Title: Acceleration of RELATIVISTIC protons in a CME-perturbed solar windAuthors: Ahmed Houeibib, Filippo Pantellini, Lea Griton,Comments:Subjects: astro-ph.SR astro-ph.HE physics.space-phCreated: 2026-07-29; Updated: 2026-07-30; Datestamp: 2026-07-30
We investigate the impact of a Coronal Mass Ejection (CME) on the transport and acceleration of RELATIVISTIC protons in the solar wind using a coupled 3D Magnetohydrodynamics (MHD) simulation and a test-particle approach. The CME is driven by a spheromak injected into a Parker solar wind at a heliocentric distance of 0.139 AU. The trajectories of 5 GeV protons, injected toward the CME from 3 AU, are integrated in the guiding-center approximation and scattered in velocity space with a mean free path $λ_{\|}$. Our results show that the CME can increase the protons' energy by several GeV. The acceleration occurs during the time particles stream along the portion of a MAGNETic field line downstream of the quasi-perpendicular portion of the CME-driven shock. In our configuration, the maximum energy gain, which is of the order of a few percent per passage through the acceleration region, occurs when the shock approaches 0.3 AU. Large energy gains require multiple passes through the acceleration region, which is made possible by the combined action of the mirror force and pitch angle scattering. The efficiency of the acceleration on time scales of the order of hours scales as $λ_{\|}^{-3/2}$. Energy spectra harden for decreasing parallel mean free path $λ_{\|}$.
[abstract 9 / 43] Yes (score: 5) - Title: Unchanged X-Ray Polarization During Accretion Dips in the Low Hard State of Cygnus X-1Authors: Yu-shan Ling, Fei Xie, Alessandro Di Marco, Fabio La Monaca, Ming-Yu Ge,Comments:Subjects: astro-ph.HECreated: 2026-07-28; Updated: 2026-07-30; Datestamp: 2026-07-30
Cygnus X-1 serves as a foundational benchmark for studying accretion mechanisms in stellar-mass BLACK HOLE X-ray binaries. While traditional X-ray timing and spectroscopy have mapped its bimodal state transitions, constraining the exact geometric configuration of its accreting plasma requires additional tools. In this letter, we present a joint spectro-polarimetric analysis of Cygnus X-1 during flux-decrease events, or ``dips'', observed in its low hard state using simultaneous data from IXPE, NICER, and NUSTAR. The broadband spectral model reveals that the energy-dependent flux reduction during these dips is best described by a partial-covering absorption model, heavily impacting the softer energy bands. This absorption is consistent with obscuration by dense, cold clumps originating from the companion's stellar wind or the outer accretion disk during superior conjunction. Notably, our polarimetric analysis demonstrates that despite significant flux drops, the POLARIZATION degree and POLARIZATION angle in the 2-8 keV band remain largely consistent between dip and off-dip intervals. The stability of the POLARIZATION signature during these highly absorbed periods indicates that the obscured thermal disk emission does not significantly contribute to the total POLARIZATION. Ultimately, these results strongly support a scenario where the X-ray POLARIZATION originates from an extended, likely oblate, accretion-disk corona whose large scale renders its overall geometry unaffected by localized clumping.
[abstract 10 / 43] Yes (score: 5) - Title: Tracing the Cosmic web across Cosmic time through SKA observations of RADIO GALAXiesAuthors: Pratik Dabhade, Gianluca Castignani, Mousumi Mahato, Shishir Sankhyayan, D. J. Saikia, Viviana Casasola, Francoise Combes,Comments: Published in Advancing Astrophysics with the SKA II (AASKAII), 2026 (arXiv:2606.20366). Report-no:AASKAII/Dabhade01. Advancing Astrophysics with the SKA II (AASKAII) outlines the transformative scientific advances that wilL be enabled by the SKA telescopesSubjects: astro-ph.GA astro-ph.COCreated: 2026-07-28; Updated: 2026-07-30; Datestamp: 2026-07-30
The Square Kilometre Array will transform studies of the cosmic web by tracing RADIO GALAXies (RGs) and star-forming systems across cosmic time with unprecedented sensitivity, angular resolution, frequency coverage, and survey speed. Powered by accreting supermassive BLACK HOLEs, RGs are not only signposts of AGN feedback but also incisive probes of their environments, from dense clusters to the low-density intergalactic medium. Their lobes, MAGNETic fields, and energy outflows encode the thermal and non-thermal histories of the surrounding gas, offering diagnostics of IGM pressure, particle ageing, and MAGNETisation over megaparsec scales. With its broad frequency coverage (50 MHz-15 GHz), microJy to sub-microJy continuum sensitivity, and wide field of view, the SKA will detect vast radio-source populations across broad ranges of redshift and environment. Measurements of source size, morphology, spectral ageing, radio power, polarisation, and Faraday rotation will reveal how the environment regulates JET propagation and lobe evolution, how radio plasma heats and MAGNETises the intracluster and intergalactic media, and how early AGN activity influences galaxy growth and STAR FORMATION in protoclusters. Combined with host identifications, spectroscopic redshifts, and optical, infrared, X-ray, Sunyaev--Zel'dovich, and cosmic-web catalogues, SKA observations will place RGs within their three-dimensional large-scale environments. This chapter presents a framework for using RGs to trace and probe the cosmic web, from nearby filaments and clusters to high-redshift protoclusters, and to test how environment, MAGNETic fields, feedback, and gas dynamics shape radio-galaxy evolution, protocluster assembly, and STAR FORMATION across cosmic time.
[abstract 11 / 43] Yes (score: 5) - Title: Observations of a Solar Jet Triggered by Reconnection between Super-penumbral Fibrils and a Mini-filamentAuthors: Liheng Yang, Xiaoli Yan, Qingmin Zhang, Zhike Xue, Zhe Xu, Jincheng Wang, Fangyu Xu, Yian Zhou, Defang Kong, Weijie Meng, Xinsheng Zhang, Qiaoling Li, Liping Yang,Comments: 18 pages, 8 figures, accepted by ApJSubjects: astro-ph.SRCreated: 2026-07-29; Updated: 2026-07-30; Datestamp: 2026-07-30
Coronal JETs are highly dynamic phenomena in the solar atmosphere, yet their driving mechanisms remain an active topic of investigation. In this paper, we report a coronal JET triggered by the interaction between super-penumbral fibrils and a mini-filament, based on coordinated observations from the New Vacuum Solar Telescope (NVST), the Chinese H$α$ Solar Explorer (CHASE), and the Solar Dynamics Observatory (SDO). The fibrils were anchored between the negative-polarity region of a sunspot and an emerging positive-polarity region associated with a moving MAGNETic feature (MMF). As the positive polarity migrated outward, the fibrils elongated and interacted with the mini-filament, one of whose footpoints was rooted in pre-existing negative-polarity fields. Intense brightenings at the interaction site, together with changes in the connectivity of the mini-filament footpoint from the pre-existing negative polarity to the sunspot, indicate the occurrence of MAGNETic RECONNECTion. The event produced a narrow hot JET accompanied by a broader cool component. The cool plasma exhibited a clockwise rotation, providing evidence for the transfer of MAGNETic twist during RECONNECTion. Persistent MAGNETic flux cancellation was observed before and during the JET eruption. These observations demonstrate that small-scale MAGNETic structures, such as MMFs, can significantly influence mini-filament eruptions and highlight the important role of flux cancellation in triggering coronal JET activity.
[abstract 12 / 43] Yes (score: 4) - Title: Resolving the BLACK HOLE sphere of influence in a hyper-luminous obscured QUASAR at redshift 4.6Authors: Mai Liao, Roberto J. Assef, Chao-Wei Tsai, Manuel Aravena, Román Fernández Aranda, Andrew W. Blain, Tanio Díaz-Santos, Peter Eisenhardt, Jorge González-López, Hyunsung D. Jun, Xiaofeng Li, Guodong Li, Lee R. Martin, Ana Posses, Devika Shobhana, Manuel Solimano, Daniel Stern, Andrey Vayner, Jingwen Wu, Dejene Zewdie,Comments: 96 pages, 43 figures, 7 tables, resubmitted, comments welcomeSubjects: astro-ph.GACreated: 2026-07-29; Updated: 2026-07-30; Datestamp: 2026-07-30
Supermassive BLACK HOLEs (SMBHs) imprint gravitational signatures on the matter within their sphere of influence (SoI). Nuclear gas dynamics can hence be used to accurately measure the mass of an SMBH, yet such measurements remain elusive in the early Universe. We report the first dynamical measurement of an SMBH mass at $z >$ 2, based on high spatial resolution observations of the [C II]157.7um and CO (12-11) 216.93um emission lines that resolve the SoI in an obscured QUASAR at $z$ = 4.6. The radial profile of the velocity dispersion reveals a clear Keplerian rise, requiring the presence of an approximately 6 $\times$ 10$^9~\rm M_{\odot}$ SMBH. We propose that obscured QUASARsallow tracers like [C II] to survive in the inner regions, and may be ideal targets for increasing dynamical SMBH mass estimates in the early Universe.
[abstract 13 / 43] Yes (score: 4) - Title: Constraints on the MAGNETic field in the hadronic scenario for the origin of the radio halo in the A1795 galaxy clusterAuthors: P. Marchegiani, V. Vacca, F. Loi, F. Govoni, M. Murgia,Comments: 5 pages, 1 appendix, 4 figures, 1 table; accepted for publication in A&ASubjects: astro-ph.HE astro-ph.COCreated: 2026-07-29; Updated: 2026-07-30; Datestamp: 2026-07-30
The radio halo in the cool-core galaxy cluster, A1795, has recently been proposed to be of hadronic origin, because it extends on megaparsec scales, where no turbulence is expected to be injected into a relaxed cluster. In this paper we aim to constrain the properties of nonthermal protons and the cluster MAGNETic field strength under the hypothesis of a hadronic origin for the radio halo in the light of the available gamma-ray upper limits for this cluster. We assumed a radial profile and several central MAGNETic field intensity values, then derived the corresponding properties of the nonthermal protons necessary to reproduce the flux density and surface brightness profile of the radio halo. For the obtained results, we calculated the corresponding gamma-ray emission and compared it with the FERMI-LAT upper limit. We find that, for a MAGNETic field energy radial profile following that of the thermal gas, central MAGNETic field intensities $B_0<5\,μ$G imply a gamma-ray emission at or above the FERMI-LAT upper limit. Therefore, larger values of the MAGNETic field are necessary in the hadronic scenario. For these values the radial profile of nonthermal protons must slightly decrease with radius, though more slowly than that of the thermal gas. For smaller values of the MAGNETic field, different mechanisms for producing or accelerating the nonthermal electrons are necessary.
[abstract 14 / 43] Yes (score: 4) - Title: Observation of poloidal MAGNETic flux emission from a low-pressure spark: validation of the hypothesis of constrained plasma dynamics?Authors: A. B. Blagoev, V. Yordanov, S. K. H. Auluck,Comments: Accepted for publication in the Physics of PlasmasSubjects: physics.plasm-phCreated: 2026-07-29; Updated: 2026-07-30; Datestamp: 2026-07-30
This paper revisits an earlier discussion of the hypothesis of constrained dynamics [IEEE Trans. Plasma Sci. 41, 2013 pp. 437-446] with better experiments and insights. This hypothesis pertains to the observation that the standard single fluid equation of motion of a current-carrying plasma has terms governed by diverse physical phenomena which are constrained to evolve at widely mismatched characteristic space and time scales. It should then be possible to construct counterexamples where the equation cannot be satisfied at all times. The hypothesis posits that the usually neglected electron inertia terms come into play in such examples and create "anomalous" electron currents whose signatures can be detected outside the plasma. One of these signatures is emission of poloidal MAGNETic flux not attributable to a helical deformation of the current channel. Following the cue of the above-mentioned paper, a series of low-pressure spark experiments have been performed. Clockwise and counterclockwise diaMAGNETic loops, an electrostatically shielded MAGNETic probe oriented to intercept the azimuthal MAGNETic flux and an electric displacement probe are deployed outside the spark channel. Observation of several expected signatures provides a tentative validation of this hypothesis. This suggests that summary neglect of electron inertia in continuum models of plasma needs to be replaced by a redevelopment of these models based on perturbation theory with an electron-mass-related small parameter. Major insights could then arise into unsolved problems such as the origin of axial MAGNETic field in astrophysical JETs. Near-solid-density MAGNETo-inertial confinement fusion may be a potential practical application.
[abstract 15 / 43] Yes (score: 4) - Title: Effect of Multi-Species Plasma on Fanaroff-Riley Radio JetsAuthors: Priyesh K. Tripathi, Indranil Chattopadhyay, Raj Kishor Jpshi, Ritaban Chatterjee, Sanjit Debnath, M. Saleem Khan,Comments: 11 pages, 5 figures. Accepted in BINA conference held in Nov 2025Subjects: astro-ph.HECreated: 2026-07-29; Updated: 2026-07-30; Datestamp: 2026-07-30
The Fanaroff-Riley (FR) dichotomy observed in extragalactic radio JETs has been attributed to a range of possible mechanisms, including intrinsic JET properties such as the presence of different species in the plasma. Jet material may span from a pure electron-positron pair plasma to mixed plasmas containing electrons, positrons, and protons, or even to hadronic JETs made up of electrons and protons only. To investigate this aspect, we present results from three-dimensional simulations of low-power, supersonic, MAGNETized JETs at kiloparsec scales in a MAGNETohydrodynamic framework. By varying the plasma composition, we show its impact on JET stability and on the development of diffuse structures typical of core-brightened FR type I sources. Our results indicate that the growth of non-axisymmetric instabilities plays a key role in disrupting the JET head.
[abstract 16 / 43] Yes (score: 4) - Title: Advanced Virgo during the LIGO-Virgo-KAGRA fourth observing runAuthors: Virgo Collaboration, F Acernese, A Agapito, D Agarwal, I-L Ahrend, L Aiello, A Ain, W Ali, A Allocca, W Amar, A Amato, F Amicucci, C Amra, M Andia, T Andri, S Antier, F Arciprete, F Armato, N Arnaud, L Asprea, M Assiduo, S Assis de Souza Melo, P Astone, F Attadio, F Aubin, G Avallone, N Avdeev, S Babak, S Bagnasco, S Baimukhametova, T Baka, G Balbi, G Baldi, N Baldicchi, G Ballardin, M Ballelli, B Banerjee, M Baratti, F Barone, M Barsuglia, D Barta, A Basti, M Bawaj, M Bazzan, F Beirnaert, M Bejger, C Bellani, D Beltran-Martinez, E Benedetti, I Bentara, S Bera, D Bersanetti, T Bertheas, A Bertolini, J Bezerra-Sobrinho, V Biancalana, F Bianchi, M Bilicki, A Binetti, S Biot, M Bitossi, M-A Bizouard, M Bloch, G Boileau, M Boldrini, R Bonnand, N Borghi, V Boschi, Y Bothra, A Boudon, A Bozzi, C Bradaschia, M Branchesi, T Briant, A Brillet, M L Brozzetti, G Bruno, F Bucci, A Buchicchio, A Buggiani, O Bulashenko, T Bulik, H J Bulten, R Buscicchio, N Busdon, D Buskulic, R Cabrita, G Cagnoli, E Calloni, E Capocasa, G Capoccia, G Capurri, F Carbognani, M Carpinelli, A Casallas-Lagos, J Casanueva Diaz, C Casentini, R Cavalieri, G Cella, P Cerd, E Cesarini, W Chaibi, E Chassande-Mottin, S Chaty, P Chessa, F Chiadini, A Chincarini, A Chiummo, A Chopra, N Christensen, G Ciani, M Cie, P Ciecielag, M Cifaldi, S Clesse, F Cleva, E Coccia, E Codazzo, P-F Cohadon, A Colombo, G Comp, L Conti, I Cordero-Carri, S Corezzi, S Cortese, L A Corubolo, A Cozzumbo, K Csuk, E Cuoco, M Cusinato, R R Cuzinatto, B D'Angelo, S D'Antonio, L D'Onofrio, D D'Urso, G D, S Dall'Osso, T Dal Canton, S Dal Pra, S Danilishin, V Dattilo, A Daumas, P Davis, J Degallaix, C J Delgado Mendez, S Della Torre, W Del Pozzo, A Demagny, G Demasi, A Depasse, J De Bolle, M De Laurentis, F De Lillo, F De Marco, F De Matteis, C de Melo, R De Pietri, R De Rosa, C De Rossi, R De Simone, S Dhage, C Diaz, F Diaz Guerra, M A Dicorato, D Diksha, J Ding, M Di Cesare, M Di Giovanni, S Di Pace, I Di Palma, D Di Piero, F Di Renzo, A Domiciano De Souza, O Dorosh, M Drago, M Dubois, U Dupletsa, H Duval, H Einsle, V Ernst, L Errico, M Esposito, F Fabrizi, V Fafone, M Fays, E Fenyvesi, A Feo, G Fern, T Fernandes, S Ferraiuolo, F Fidecaro, P Figura, I Fiori, V Fiumara, R Flaminio, F Flocco, J A Font, A Fragkos, N Franchini, F Frappez, F Frasconi, A Freise, O Freitas, S Galaudage, M Galimberti, B Garaventa, J Garc, P Garc, J Gargiulo, X Garrido, F Garufi, C Gasbarra, F Gautier, G Gemme, A Gennai, V Gennari, A Ghinassi, Archisman Ghosh, F Gittins, F Glotin, E Glowacki, S Gomez Lopez, A Goodwin-Jones, M Gosselin, C Gostiaux, R Gouaty, D Goupilliere, A Grado, M Granata, V Granata, G Greco, A C Green, C Grimaud, G M Guidi, F Gulminelli, Y Guo, M Haney, S Harikumar, J Harms, M T Hartman, B Haskell, D Hegde, H Heitmann, G Hemming, J Heynen, S Hild, D Hofman, L Honet, W-F Hsu, L Iampieri, G A Iandolo, M Ianni, A Ierardi, P Iosif, J Irwin, C Jacquet, T Jacquot, J Janquart, S Jaraba, P Jaranowski, G Joubert, B Kacskovics, A Karia, W Kiendrebeogo, S Koley, A E Koloniari, A Kr, E Kraja, S L Kranzhoff, J Kubisz, S Kuroyanagi, N Lajili, A Lakhal, M Lalleman, J A Lange, A Lartaux-Vollard, L Lavezzi, C Lazzaro, P Leaci, F Legger, A Lema, R Lemrani Alaoui, M Lenti, M Leonardi, M Lequime, N Letendre, M Lethuillier, S Lexmond, M Le Jean, T G F Li, F Liu, J-P Locquet, A Longo, M Lopez Portilla, M Lorenzini, V Loriette, M Lorusso, G Losurdo, D Lumaca, L Lunghini, A Macquet, S S Madekar, S Maenaut, E Maggio, M Magnozzi, E Majorana, N Man, M Mancarella, V Mangano, M Mantovani, M Mapelli, S Marchetti, F Marion, S Marsat, F Martelli, M Martinez, V Martinez, A Martini, J C Martins, L Massaro, A Masserot, S Mastrogiovanni, G Mastropasqua, L Maurin, L G Medeiros, L Mereni, C Michel, E Milotti, V Milotti, E Minakaki, Y Minenkov, Ll. M Mir, L Mirasola, C-A Miritescu, L Mobilia, M Montani, G Montefusco, A Moreso Serra, G Morras, A Moscatello, B Mours, C M Mow-Lowry, L Muccillo, F Muciaccia, D Nabari, S Nadji, A Nagar, D Nanadoumgar-Lacroze, V Napolano, A Nardecchia, I Nardecchia, H Narola, L Naticchioni, L Negri, A Nemmani, T C K Ng, S Nissanke, F Nocera, J Novak, M Oertel, G Oganesyan, R Oliveira, A Ouzriat, M A Palaia, C Palomba, P T H Pang, F Pannarale, M Panzeri, F Paoletti, A Paoli, A Paolone, L Papalini, G Papigkiotis, A Paquis, A Parisi, D Pascucci, A Pasqualetti, D Passuello, B Patricelli, K Paul, A Perreca, J Perret, D Pesios, C Petrillo, L Piccari, M Pichot, M Piendibene, F Piergiovanni, L Pierini, G Pierra, V Pierro, M Pillas, L Pinard, I M Pinto, M Pinto, A Pisarski, E Placidi, R Poggiani, E Polini, M Polo, J Pomper, E Porcelli, E K Porter, M Pracchia, G Principe, G A Prodi, P Prosperi, P Prosposito, M Punturo, P Puppo, G Qu, I Rainho, P Rapagnani, M Razzano, T Regimbau, A I Renzini, B Revenu, A Revilla-Pe, F Ricci, M Ricci, A Ricciardone, A Riminucci, F Robinet, A Rocchi, L Rolland, R Romano, A Romero-Rodr, S Ronchini, D Rosi, S Roy, D Rozza, P Ruggi, E Ruiz Morales, F Safai Tehrani, P Saffarieh, T Sainrat, S Sajith Menon, L Salconi, F Salemi, M Sall, M Salom, S Salvador, A Samajdar, N Sanchis-Gual, F Santoliquido, F Sarandrea, P Sassi, B Sassolas, M Schoor, K Schouteden, M Schulz, M Scialpi, M Seglar-Arroyo, J W Seo, V Sequino, M Serra, A Sevrin, L Silenzi, P J S Silva, L Silvestri, L Smith, S Soares de Albuquerque Filho, V Sordini, F Sorrentino, F Spada, V Spagnuolo, M Spera, P Spinicelli, D A Steer, J Steinlechner, S Steinlechner, N Stergioulas, M Suchenek, S Sudhagar, J Sun, J Suresh, A Svizzeretto, B L Swinkels, A Syx, M J Szczepa, M Tacca, M Tagliazucchi, I Takimoto Schmiegelow, N Tamanini, L Tao, E N Tapia San Mart, A Theodoropoulos, J Tissino, P Tiwari, E Tofani, M Toffano, I Tosta e Melo, E Tournefier, A Trapananti, R Travaglini, F Travasso, M C Tringali, G Troian, A Trovato, L Trozzo, M Turconi, C Turski, H Ubach, M Vacatello, M Valentini, E Vallejo-Pag, S Vallero, M van Dael, E Van den Bossche, J F J van den Brand, C Van Den Broeck, M van der Kolk, M van der Sluys, A Van de Walle, J van Dongen, H van Haevermaet, J V van Heijningen, P Van Hove, N van Remortel, M Vardaro, G Vedovato, S Venikoudis, P Verdier, M Vereecken, D Verkindt, S Verma, F Vetrano, A Veutro, A Vicer, N Villanueva Espinosa, J-Y Vinet, S Viret, H Vocca, M Was, M Wils, I C F Wong, T Wouters, M Wright, Z Wu, N Yadav, M Zanatta, T Zelenova, J-P Zendri, M Zeoli, M Zerrad, J Zhang, Y Zhao, L Zhizhong, L Zimmermann,Comments: 54 pages, 21 figuresSubjects: gr-qcCreated: 2026-07-29; Updated: 2026-07-30; Datestamp: 2026-07-30
From April 10, 2024 to November 18, 2025 Advanced Virgo participated in the fourth observing run of the network of gravitational-wave detectors, together with Advanced LIGO and KAGRA. For this observing run Advanced Virgo has completed its design optical configuration with the installation of a signal recycling mirror. In this paper we describe the challenges encountered in commissioning this optical configuration, alongside the other upgrades performed between the third and fourth observing run. The Virgo detector operated with a 68.9% duty cycle and with an angle-averaged median range to binary neutron star mergers of 53 Mpc.
[abstract 17 / 43] (score: 3) - Title: Central Equations and Band Structures of Linear Magnetohydrodynamic Waves in a Magneto-LatticeAuthors: Shiyu Sun, Peifeng Fan, Yulei Wang, Qiang Chen, Xingkai Li, Weihua Wang,Comments:Subjects: physics.plasm-phCreated: 2026-07-29; Updated: 2026-07-30; Datestamp: 2026-07-30
We investigate the band structures and propagation properties of linear ideal MAGNETohydrodynamic (MHD) waves in a plasma with a spatially periodic background MAGNETic field (a MAGNETo-lattice ). We develop a plane-wave expansion approach in two equivalent forms: one written using the usual linearized MHD perturbation variables and another written in terms of the fluid displacement. We validate both formulations with numerical tests, including an empty-lattice limit that recovers the uniform-plasma dispersion. The method enables efficient computation of dispersion relations and reveals intrinsic frequency band gaps and cutoff behavior caused by MAGNETic periodicity. We show that the band gap width increases with the amplitude of the periodic MAGNETic-field modulation (relative to the uniform background field), leading to suppression of selected wave modes. In addition, the MAGNETic periodicity splits the Alfvén continuum into multiple branches, a feature absent in uniform plasmas. These results provide a framework for tailoring MHD wave propagation in structured plasmas and may be useful for future studies of plasma metamaterials and topological plasma waves.
[abstract 18 / 43] (score: 3) - Title: MeV-peaked electrons in a coronal source of a solar flareAuthors: Gregory D. Fleishman, Ivan Oparin, Gelu M. Nita, Bin Chen, Sijie Yu, Dale E. Gary,Comments: Published in Nature Astronomy; 15 pages; 8 figuresSubjects: astro-ph.SR astro-ph.HECreated: 2026-07-28; Updated: 2026-07-30; Datestamp: 2026-07-30
Analysis of γ-rays in solar flares has suggested a distinct continuum component dominating at MeV energies, which differs from the well-studied X-ray continuum produced by flare-accelerated electrons with spectra steeply falling with energy. The origin, precise spatial location, and extent of this mysterious MeV component have been unknown up to now. If it is produced by bremsstrahlung, such a γ-ray component requires an unusual population of electrons peaked at a few MeV. Here we report a joint study of this MeV-peaked electron population in the 2017-Sep-10 solar flare with FERMI MeV γ-ray data and EOVSA spatially resolved microwave imaging spectroscopy data. We demonstrate that the microwave spectrum from the MeV-peaked distribution has a distinctly different shape from that produced by the electrons with falling energy spectrum. We inspected microwave maps of the flare and identified an evolving area where the measured microwave spectra matched the theoretically expected one for the MeV-peaked population, thus pinpointing the site where this MeV component resides. The locations are in a coronal volume adjacent to the region where prominent release of MAGNETic energy and bulk electron acceleration were detected, which implies that transport effects play a key role in forming this population.
[abstract 19 / 43] (score: 3) - Title: Gamma-ray burst progenitors revisitedAuthors: Andrew J. Levan, Jillian C. Rastinejad, Helena-Margaret S. Grabham, Daniele B. Malesani, Nial R. Tanvir, Eric Burns, Benjamin P. Gompertz, Gavin P. Lamb, Ashley A. Chrimes, Peter G. Jonker, Om Salafia, Nikhil Sarin, Ilya Mandel, Antonio Martin-Carrillo,Comments: Submitted to MNRAS. 28 pages, 13 figures, 6 tablesSubjects: astro-ph.HECreated: 2026-07-28; Updated: 2026-07-30; Datestamp: 2026-07-30
Recently, several long-duration GAMMA-RAY BURSTs (GRBs) associated with kilonovae have cast doubt on the traditional, dichotomous mapping between gamma-ray duration and progenitor system. Here, we investigate the rates and properties of bursts which appear to cross this dichotomy using a sample of GRBs for which progenitor constraints are possible. We first build a sample of known SWIFT-detected GRBs at z<0.3, finding 8 short- and 21 long-duration GRBs. Of these long GRBs, we find 9 bursts with deep limits on SUPERNOVA emission, evidence for kilonova emission, or association with a quiescent galaxy (31% $\pm$ 9% of all GRBs at z<0.3), implying that a significant fraction of nearby long GRBs likely do not come from massive stars. At z<0.3, no short GRB has an observed SUPERNOVA counterpart. We find comparable numbers when expanding to z<0.5 and other gamma-ray telescopes, though we obtain a decreased fraction of bursts with robust constraints on a progenitor. We further find that the long GRBs with no associated SUPERNOVAe possess on-average fainter afterglows and lie in less star-forming host galaxies than those with SUPERNOVAe, supporting that these events may originate in compact object mergers. We estimate approximate volumetric rates, finding similar (on-axis) rates for short GRBs and SUPERNOVA-less long GRBs of $\sim 0.5-2.5$ Gpc$^{-3}$ yr$^{-1}$, although a search for possible low-redshift hosts of the complete SWIFT catalog suggests that our sample may be $\sim$50% complete. If SUPERNOVA-less long GRBs arise from compact object mergers, this implies that $\sim$ 30-70% of all z<0.3 SWIFT long GRBs may arise from mergers and that the $z<0.3$ rates of mergers from long and short GRBs are comparable. These findings hold substantial implications for gravitational-wave coincidence and heavy element enrichment.
[abstract 20 / 43] (score: 3) - Title: X-ray and optical decline of the intermediate mass BLACK HOLE HLX-1Authors: Roberto Soria, Maya Garbaccio Gili, Francesco Massaro, Alister W. Graham, Luca Zampieri,Comments: 19 pages, 4.9 MB, accepted by PASASubjects: astro-ph.HE astro-ph.GACreated: 2026-07-28; Updated: 2026-07-30; Datestamp: 2026-07-30
HLX-1 is a prominent intermediate-mass BLACK HOLE (IMBH) candidate, historically exhibiting recurrent X-ray outbursts with spectral state transitions analogous to those observed in stellar-mass BLACK HOLEs. Here, we present new Hubble Space Telescope, Chandra, and SWIFT observations from 2018-2022 to characterise the late-time flux decline. HLX-1 has persisted in a low X-ray luminosity state (L_X ~ a few x 10^{39} erg/s) since the end of its last outburst in 2017. We observe a significant decoupling between the X-ray and optical/UV emission: while the X-rays have faded by at least two orders of magnitude from peak outburst luminosity (in 2010) to the current low state, the optical/UV flux has declined much more slowly over the same time. This results in an X-ray/optical luminosity ratio inconsistent with X-ray reprocessing in a standard accretion disk, as this would require an unphysical reprocessing fraction >100% at late times. Instead, we find that the optical/UV evolution is well-fitted by a cooling, expanding photosphere (T ~ 30,000 K), similar to the late-stage evolution seen in tidal disruption events (TDEs). The redder component of the optical emission is instead consistent with the old stellar population of a massive star cluster (IMBH host). The pre-2017 X-ray bursting phase is consistent with simulations of disk instabilities in TDE evolution: this strengthens the scenario of HLX-1 as an IMBH TDE. Furthermore, our observations resolve the morphology and flux of the mysterious far-UV emitter, seen in projection next to HLX-1, into a ring-like star-forming structure. We re-assess the possibility that HLX-1 and its host star cluster are physically associated with this starburst dwarf, perhaps via a high-speed collision.
[abstract 21 / 43] (score: 3) - Title: Low-Temperature Co-Fired Ceramics for a Sustainable Planar Plasma Jet with Homogeneous Plasma in Large Treatment Areas for Biomedical ApplicationsAuthors: Ivan Gomez Ho, Hua-Lin Chen, Cheng-Han Tsai, Jong-Shinn Wu, Yun-Chien Cheng,Comments: 31 pages, 15 figuresSubjects: physics.plasm-phCreated: 2026-07-29; Updated: 2026-07-30; Datestamp: 2026-07-30
This study presents a portable planar argon-based plasma JET designed for large-area biomedical applications, with an emphasis on uniform discharge, stability, and safety. The device incorporates interchangeable rear and side inlet gas adapters with restriction plates and channels to equalize gas flow, while electrodes are encapsulated in low-temperature co-fired ceramics to reduce degradation and arcing during repeated operation. Flow simulations were conducted for multiple channel configurations to ensure laminar gas distribution and uniform plasma generation. Device performance and safety were evaluated using the kinPen MED as a reference standard. Electrical characteristics, optical emission, discharge uniformity, temperature, gas velocity, ozone generation, UV irradiance, and leakage current were systematically measured. The plasma exhibited stable voltage, current, and power after an initial warm-up period. Temperatures stabilized within minutes, with the rear-inlet configuration demonstrating lower operating temperatures due to higher outlet gas velocity. Ozone levels remained below established safety limits, while UV exposure constrained allowable treatment times. Leakage current decreased with increasing distance and approached safety thresholds at short separations. These results demonstrate that the proposed planar plasma JET provides stable, uniform plasma delivery while meeting key safety requirements, supporting its potential for clinical and biomedical use.
[abstract 22 / 43] (score: 3) - Title: SPECTRE: A robust solver for 3D equilibria with arbitrary topologyAuthors: E. Balkovic, J. Loizu, E. Lanti, C. Smiet, C. Lazzati, R. Ramasamy, A. Goodman, J. Geiger, J. P. Graves,Comments:Subjects: physics.plasm-ph physics.comp-phCreated: 2026-07-29; Updated: 2026-07-30; Datestamp: 2026-07-30
We present SPECTRE, a new equilibrium code based on the Multi-Region relaxed MHD model for robustly calculating 3D equilibria with general MAGNETic topology, allowing for flux surfaces, MAGNETic islands, and chaos. The code builds on a previous MRxMHD solver, SPEC, but performs significantly better thanks to a new formulation of force, the use of a stable trust-region-based least squares minimization scheme, as well as several additional features. SPECTRE is verified through application to configurations with known equilibrium solutions, in vacuum and with finite beta, both in the fixed boundary and the free boundary mode. Notably, these include vacuum equilibria of a quasi-axisymmetric (QA) device in fixed-boundary mode, and of W7-X in the free-boundary mode, along with a classical stellarator finite-beta free-boundary case. Finally, the solver is applied to a modern optimized finite-beta quasi-isodynamic (QI) configuration, where we demonstrate calculation of a strongly-shaped equilibrium with a core island which is in agreement with a HINT calculation.
[abstract 23 / 43] (score: 2) - Title: Projection method for mean resolvent analysis of periodic flowsAuthors: Alessandro Bongarzone, Cédric Content, Denis Sipp, Colin Leclercq,Comments:Subjects: physics.flu-dynCreated: 2026-07-28; Updated: 2026-07-30; Datestamp: 2026-07-30
The mean resolvent operator predicts the mean linear response to forcing in the frequency domain and provides the optimal linear time-invariant approximation of statistically steady, time-varying flows [1]. We first leverage the harmonic resolvent framework [2,3] in order to propose an algorithm for performing mean resolvent analysis of a periodic flow. Next, we propose an alternative approach which does not explicitly rely on the harmonic resolvent framework. The approach leverages the fact that the mean-flow resolvent approximates the mean resolvent operator; therefore, the optimal forcing modes of the latter operator may be sought in a subspace spanned by optimal modes of the former. This projection approach does not require computing the adjoint dynamics about the attractor, which may be convenient for future extensions to more chaotic and turbulent flows. The present paper is, however, focused on periodic flows, where the convergence of the projection approach can be checked in comparison to the `ground truth' provided by the harmonic resolvent framework. This test is performed on a nearly incompressible axisymmetric laminar JET forced harmonically at the inlet. For the weakly unsteady case, the mean-flow resolvent captures the dominant receptivity peak but misses a secondary one present in the mean resolvent gain. For the strongly unsteady case, the mean-flow resolvent fails to predict the frequency of the vortex-pairing, while the mean resolvent correctly locates the corresponding gain peak. The projection method converges with a subspace dimension of 10 in the weakly unsteady case, while about 100 modes are required for accurate predictions in the strongly unsteady regime. Nonetheless, even a one-dimensional subspace correctly identifies the dominant receptivity peak.
[abstract 24 / 43] (score: 2) - Title: ElectroMAGNETic turbulence in EAST plasmas with internal transport barrierAuthors: Yuehao Ma, Pengfei Liu, Jian Bao, Zhihong Lin, Huishan Cai,Comments: Final version published in Nuclear FusionSubjects: physics.plasm-phCreated: 2026-07-29; Updated: 2026-07-30; Datestamp: 2026-07-30
In this study, global nonlinear electroMAGNETic gyrokinetic simulations are conducted to investigate turbulence in the Internal transport barrier (ITB) region of the EAST tokamak discharge with weakly reversed MAGNETic shear. Linear simulations reveal two dominant ion temperature gradient (ITG) modes: a higher frequency mode at the $q=1$ surface, which dominates in the electrostatic limit, and a lower frequency mode near the $q_{\min}$ surface, which prevails under the experimental $β$ (the ratio of plasma pressure to MAGNETic pressure). Finite $β$ effects effectively suppress higher frequency ITG modes, and once $β_i$ on axis exceeds 0.5\%, this ITG mode is no longer dominant, and the ITG mode near $q_{\min}$ surface becomes the primary instability. Therefore, electroMAGNETic effects play a crucial role in stabilizing ITG modes, and in causing the transition between the most unstable mode at different radial positions. The linear growth rate of the unstable mode in the electrostatic limit is approximately 1.25 times higher than that of the dominant mode in the electroMAGNETic case. However, in the electroMAGNETic nonlinear regime, the thermal ion heat conductivity is reduced by at least a factor of 4. This reduction primarily results from nonlinear electroMAGNETic effects enhancing the shearing effect of zonal flows, thereby further suppressing microturbulence. Finally, energetic particles exert a slight stabilizing effect on ITG turbulence due to dilution and finite $β$ contributions. It is emphasized that the electroMAGNETic effect on ITG with weak MAGNETic shear should be included to accurately calculate the transport coefficients.
[abstract 25 / 43] (score: 2) - Title: Cross-scale Interaction between Microturbulence and Fishbone in Fusion PlasmasAuthors: Yuehao Ma, Bin Zhang, Pengfei Liu, Jian Bao, Zhihong Lin, Huishan Cai, Liutian Gao, AhDi Liu, Hailin Zhao, Tao Zhang,Comments: Final version published in Physical Review ResearchSubjects: physics.plasm-phCreated: 2026-07-29; Updated: 2026-07-30; Datestamp: 2026-07-30
Global gyrokinetic simulations are performed for the first time to investigate cross-scale interactions between electroMAGNETic ion temperature gradient (ITG) turbulence and fishbone instability in tokamak plasmas. The investigation of fluctuation response in the multiscale simulation including both instabilities indicates a strong impact of fishbone on ITG turbulence. Detailed analysis reveals that fishbone-driven zonal radial electric fields at nonlinear saturation significantly suppress electroMAGNETic ITG turbulence, reducing ion thermal transport close to the neoclassical level. The simulation results agree well with experimental observations that turbulence suppression during fishbone bursts. These findings advance understanding of multiscale interactions that enhance thermal confinement in fusion plasmas.
[abstract 26 / 43] (score: 2) - Title: Padé Approximants for cosmic Dispersion MeasuresAuthors: Marios Kalomenopoulos, Jiaming Zhuge,Comments: Manuscript prepared to submit to OJA (only template change from previous upload). Comments welcome!Subjects: astro-ph.HE astro-ph.COCreated: 2026-07-29; Updated: 2026-07-30; Datestamp: 2026-07-30
Fast Radio Bursts (FRBs) have become an indispensable tool for studying the ``missing baryons'', the Universe's ionisation properties, as well as the cosmological parameters. This is achieved by analysing the diffuse dispersion measure (${\rm DM}_{\rm diff}$) of FRBs as a function of redshift. However, the rapidly increasing data size requests more and more computational resources. In this work, we first develop an accelerated method for any cosmic dispersion measure by deriving an analytical approximation formula for flat, $Λ$CDM and $w$CDM universes. Focusing on FRBs, we show that our approximation works well for the ranges $0.01 \leq z \leq 2$, $0.2 \leq Ω_m \leq 1.0$ and $-3.0 \leq w \leq -0.5$, with relative error to a numerically evaluated ${\rm DM}_{\rm diff}$ always smaller than $3.5 \%$ (in the worst case scenario). This error remains below observationally relevant ${\rm DM}$ scatter and is especially small near the concordance $Λ$CDM cosmology. Additionally, we perform a cosmological analysis of simulated FRB data and show that our approximation gives robust and unbiased results, even when applied in regions of parameter space where its relative error becomes larger than $3\%$. Finally, the approximation is more than $15$ ($2$) times faster than the numerical solution of $Λ$CDM ($w$CDM), and can reach a timing improvement of a factor of $25$ when used in an MCMC cosmological inference.
[abstract 27 / 43] (score: 2) - Title: Cherenkov plasmons emission by primordial neutrinosAuthors: Maxim Dvornikov,Comments: 17 pages in pdflatex, 3 pdf and 1 png figures, appendices are shortened, several misprints are correctedSubjects: hep-ph astro-ph.CO astro-ph.HE physics.plasm-phCreated: 2026-07-29; Updated: 2026-07-30; Datestamp: 2026-07-30
We study the emission of Cherenkov plasmons by the gas of neutrinos with a nonzero temperature and a chemical potential. The background plasma, consisting of charged leptons, is taken to be nonRELATIVISTIC. The energy emission rate is obtained for longitudinal plasmons. To get the neutrino emissivity we average quantum field theory matrix element over the distribution functions of incoming and outgoing particles. Our results are applied for the description of the cooling down of a neutrino cluster formed in the early universe. Such clusters can exist owing to the neutrino interaction with a hypothetical light scalar BOSON. Using particular cluster parameters, we demonstrate that the considered cooling mechanism is efficient for some clusters. We find the temperature range where the proposed cooling channel is valid. Some useful calculations of the POLARIZATION tensor, as well as the plasmon form factors and their dispersion relations are also provided.
[abstract 28 / 43] (score: 2) - Title: Constraints on High-Frequency Gravitational Waves from Graviton-Photon Conversion in the M87 GalaxyAuthors: Aman Gupta, Pratik Majumdar, Sourov Roy, Pratick Sarkar,Comments: 19 pages, 8 figures, Version accepted for publication in Physical Review DSubjects: hep-ph astro-ph.HECreated: 2026-07-29; Updated: 2026-07-30; Datestamp: 2026-07-30
High-frequency gravitational waves, particularly in the range $f \gtrsim 10^{10}~\mathrm{Hz}$, represent a compelling probe of physics beyond the Standard Model. Due to the absence of direct detection methods in this frequency regime, alternative strategies may be pursued. One promising approach involves the conversion of gravitons into photons in the presence of MAGNETic fields, a process known as the inverse Gertsenshtein effect. In this study, we explore such graviton-to-photon conversions occurring within the MAGNETic field environment of the M87 galaxy, utilizing realistic models for the galactic MAGNETic field and plasma density structure. We use the broadband electroMAGNETic spectrum of M87, ranging from millimeter to TeV gamma rays, to search for hidden contributions from graviton-photon conversions. In the well-constrained frequency range $10^{10}$-$10^{27}~\mathrm{Hz}$, the lack of excess emission allows us to place improved bounds on the gravitational wave strain amplitude $h_c$ or on spectral energy density $Ω_{\mathrm{gw}} h^2$. We find that our results from M87 yield substantially stronger constraints compared to existing bounds derived from Milky Way MAGNETic field considerations, with improvements ranging from one to five orders of magnitude depending on the frequency band, thereby enhancing the prospects for probing high-frequency gravitational wave backgrounds through indirect electroMAGNETic signatures.
[abstract 29 / 43] (score: 2) - Title: Dependences of radio pulsar parameters on the bimodal kick modeAuthors: Anton D. Lazarev, Sergei B. Popov,Comments: 10 pages, 9 figures. Submitted to OJApSubjects: astro-ph.HECreated: 2026-07-29; Updated: 2026-07-30; Datestamp: 2026-07-30
Analysis of observational data and theoretical modeling favors a bimodal distribution of the natal velocity kick of neutron stars. For $\sim200$ normal isolated radio pulsars with well-determined spin and kinematic parameters, we determine if they belong to the low- or high-velocity mode of the distribution. Our results demonstrate that about $30\%$ belong to the low-velocity mode. We then analyze the differences in the properties of the two sets of pulsars. For some parameters (characteristic ages, distances, and radio luminosities), we see a clear difference between the two modes. However, for these quantities, it can be easily attributed to selection bias. For those parameters that are not a subject of strong selection, such as pulse width, we do not observe any difference. Interestingly, we detect a significant difference in the MAGNETic field distribution between the two modes. Lower field pulsars ($B\lesssim 10^{12}$~G) are overabundant among objects from the low-velocity mode in comparison to the high-velocity one. Among pulsars with low field ($\lesssim 10^{11}$~G), we do not identify any objects from the high-velocity mode of the kick distribution. The origin of this discrepancy is not clear, and we discuss several possibilities.
[abstract 30 / 43] (score: 2) - Title: Contribution of cosmic alphas to generation of albedo neutrons and gammas in lunar regolith: A computational study based on GEANT4 simulationsAuthors: Harshala Gaonkar, A. Ilker Topuz,Comments: 9 pages, 6 figures, 2 tablesSubjects: physics.ins-det astro-ph.HECreated: 2026-07-29; Updated: 2026-07-30; Datestamp: 2026-07-30
The lunar surface is constantly and directly exposed to Galactic Cosmic Rays (GCRs) due to the lack of the atmosphere and the MAGNETic field around it. The high-energetic alpha particles subsequently contribute to the generation of the secondary neutrons through either the spallation reaction or the low-energetic $(α, n)$ process along with the cosmic protons. In this study, the contribution of the alpha particles to the production of the albedo neutrons as well as the albedo gamma rays in the lunar regolith is studied by using the Monte Carlo simulations based on the GEANT4 toolkit. The incident alpha particles are referenced from the PAMELA spectrometer over the interval between 0.14 and 52 GeV and executed as a probability-based primary particle source. The present simulations demonstrate the production of the albedo neutrons and gamma rays upon the process of cosmic alpha irradiation in the lunar regolith. The albedo neutron production is predominantly situated within the near-surface region of the lunar regolith and progressively diminishes with the increasing depth. The population of the secondary neutrons is primarily distributed over the low-energy region and reduces towards the high energies. These results imply that the cosmic alpha particles have also quantifiable contribution in the generation of the secondary radiation at the lunar surface together with the cosmic protons, and this study demonstrates a computational framework in the evaluation of the lunar albedo, the radiation transport, the surface composition, and the radiation environment for the further lunar exploration missions.
[abstract 31 / 43] (score: 2) - Title: Emulating the complex galactic-scale orbital dynamics of LISA massive BLACK HOLE pairs with normalizing flowsAuthors: Pedro R. Capelo, Carlos Moreno Martinez, Nodens Koren, Tommaso Zana, Elisa Bortolas, Matteo Bonetti, Janis Fluri, Thomas Hofmann, Lucio Mayer,Comments: 23 pages, submitted to MNRASSubjects: astro-ph.GA astro-ph.CO astro-ph.HECreated: 2026-07-28; Updated: 2026-07-30; Datestamp: 2026-07-30
Massive BLACK HOLE (MBH) pairs, formed in galaxy mergers, may coalesce in a burst of gravitational waves. Estimating the coalescence time-scales and rates is a long-standing astrophysical problem, essential to inform predictions for future gravitational-wave detectors such as the Laser Interferometer Space Antenna, but remains challenging: MBH orbital decay in realistic galactic environments is complex and stochastic, and non-axisymmetric structures such as stellar bars can perturb MBH pair dynamics, delaying or accelerating binary formation and undermining the assumption that dynamical friction alone sets the inspiral duration. Capturing this evolution requires simulations too expensive to run at population scale. Here we present an artificial-intelligence framework that emulates the galactic-scale orbital decay of an inspiralling MBH using conditional normalizing flows trained on a large suite of semi-analytical orbital integrations. Our model captures the evolution of secondary MBHs orbiting within multi-component galactic merger remnants featuring rotating stellar discs and bars, across a broad range of MBH masses, orbital configurations, and bar properties. The trained emulator reproduces the simulations' decay-time distributions while reducing computational cost by orders of magnitude. For the first time, we apply this model to galaxy populations drawn from a cosmological simulation, exploiting morphological information on barred and non-barred galaxies to infer MBH binary formation time-scales across cosmic time. Our results show that stellar bars can alter the distribution of MBH binary formation times. More broadly, this demonstrates how simulation-based, surrogate machine-learning emulators can unlock a class of astrophysical problems where the physics is well understood system-by-system but intractable at scale.
[abstract 32 / 43] (score: 2) - Title: From S2 to LISA: Astrometric Bounds on Extreme-Mass-Ratio Inspirals and BurstsAuthors: Andrea Caputo, Valerie Domcke,Comments: 22 pages, 10 figures; Claude Code-generated repository reproducing all results at https://github.com/andrea0292/s2-to-lisaSubjects: astro-ph.GA astro-ph.CO astro-ph.HE gr-qcCreated: 2026-07-28; Updated: 2026-07-30; Datestamp: 2026-07-30
Stellar orbits around the massive BLACK HOLE at the center of our galaxy provide a unique local probe of the compact-object population in the Galactic Centre and, consequently, of the sources of millihertz gravitational waves: periapse passages lead to extreme-mass-ratio bursts (EMRBs) while successful captures lead to extreme-mass ration inspirals (EMRIs). In this paper we use recent astrometric limits from the GRAVITY observatory on perturbations of the orbit of the star S2 to place upper limits on the normalisation of a stellar-mass black-hole cusp within ${\sim} \,0.02\,\mathrm{pc}$. For a benchmark $10\,M_\odot$ Bahcall--Wolf population anchored to this data, we obtain upper limits of ${\sim} \,2.4\times10^{2}\,\mathrm{Gyr}^{-1}$ on the EMRI rate and ${\sim} \, 0.2\,\mathrm{yr}^{-1}$ on the detectable EMRB rate in the Milky Way, which fall within the broad range of previous theoretical estimates. Assuming a self-similar scaling of the cusp normalisation with central black-hole mass, we extend this calibration to cosmological populations. The resulting EMRI background is detectable by LISA across all scenarios considered, whereas the flatter EMRB background can reach LISA sensitivity when mass segregation is efficient in low-mass galactic nuclei. Our results highlight the complementarity of precision stellar astrometry and millihertz gravitational-wave observations.
[abstract 33 / 43] (score: 2) - Title: Stellar rotation of S301 as a macroscopic gyroscope to test general relativityAuthors: Pau Amaro Seoane, Xian Chen, Alejandro Torres-Orjuela, Reinhard Genzel, Frank Eisenhauer, Thomas Ott, Stefan Gillessen, Guillaume Bourdarot, Diogo C. Ribeiro, Matteo Sadun Bordoni, Simran Joharle, Felix Mang, Andreas Burkert, Jorge Cuadra, Diego Calderón, Hagai B. Perets, Tsvi Piran, Thorsten Naab, Re'em Sari,Comments: SubmittedSubjects: astro-ph.GA gr-qcCreated: 2026-07-28; Updated: 2026-07-30; Datestamp: 2026-07-30
Stellar trajectories around the Galactic Center provide a testing environment for general relativity. The intrinsic rotation of these stars evolves under covariant transport in curved spacetime and classical Newtonian quadrupole torques. We analyze the recently observed S301 S-star to quantify the RELATIVISTIC precession of its rotational axis. Its 8.7-year period and eccentricity of $e = 0.982$ localize geodetic precession and Newtonian quadrupole torques to a step function at periapsis. We incorporate first-order post-Newtonian corrections into the orbital kinematics to calculate the spatial trajectory. Sampling an isotropic distribution of initial orientations and viewing geometries over a 40-year period across a grid of equatorial velocities and rotational ellipticities, we calculate the statistical likelihood of an absolute shift in the projected rotational line broadening, $|Δv \sin i|$. The RELATIVISTIC geodetic shift scales linearly with $v_{\rm rot}$ and the classical quadrupole shift is independent of rotation speed, scaling with $q$. The absolute maximum velocity shift saturates at $46.1\,\kms$ for oblate stars. The absolute median shifts, driven by geodetic precession, range from $3\,\kms$ to $6.3\,\kms$. We calculate the time-domain observable $|Δv \sin i|$ to provide a target for infrared spectrographs testing the Schwarzschild metric around Sgr~A$^\ast$. The spin of S301 acts as a flying gyroscope whose drift, if measured, can test Einstein's theory in a regime that has not previously been accessible.
[abstract 34 / 43] (score: 2) - Title: Light propagation and intensity transport in metric-affine geometryAuthors: Antonio De Felice, Lavinia Heisenberg, Gonzalo J. Olmo, Carlos Pastor-Marcos,Comments: 10 pagesSubjects: gr-qcCreated: 2026-07-28; Updated: 2026-07-30; Datestamp: 2026-07-30
We study electroMAGNETic wave propagation in metric--affine geometries, where torsion and non-metricity may be present and the coupling between electroMAGNETism and spacetime is no longer unique. Rather than choosing a particular coupling prescription a priori, we construct electroMAGNETic sectors that preserve standard $U(1)$ gauge invariance and projective invariance of the affine connection as guiding symmetry principles. We introduce two representative models, one in which the Maxwell term is dressed by a scalar prefactor built from non-Riemannian invariants, and another in which the kinetic term is modified by a rank--four constitutive tensor acting as an anisotropic medium. We derive their geometric--optics limits and show that their couplings can modify the effective light cone, change the relation between field amplitude and intensity, induce POLARIZATION-dependent propagation, and generate birefringence and mode mixing. These results thus provide the formal basis for a broader phenomenological study connecting torsion and non-metricity with electroMAGNETic observables in concrete metric--affine backgrounds, including black-hole imaging, birefringent lensing, POLARIZATION observables, and departures from photon-number conservation.
[abstract 35 / 43] (score: 2) - Title: How to raise a supermassive BLACK HOLE: interpreting early JWST AGN with the AESOPICA simulationsAuthors: Sophie Koudmani, Jan Scholtz, Anthony J. Taylor, Ignas Juodžbalis, Debora Sijacki, Rachel S. Somerville, Roberto Maiolino, Emma Curtis-Lake, Steven L. Finkelstein, Martin A. Bourne, Francesco D'Eugenio, Sophia Geris, Lucy R. Ivey, Hannah Übler,Comments: 31 pages, 15 figures. Submitted to MNRAS. Comments welcomeSubjects: astro-ph.GA astro-ph.HECreated: 2026-07-28; Updated: 2026-07-30; Datestamp: 2026-07-30
The active BLACK HOLEs uncovered by JWST in the early Universe are highly abundant and seemingly overmassive with respect to local scaling relations, challenging standard models of BLACK HOLE formation and growth. Yet it remains unclear whether they trace an efficient early growth channel, the observable tail of a broader population, or suffer from systematic uncertainties in mass estimates. We introduce the AESOPICA project, a suite of twelve mid-volume ($L = 60\,\mathrm{Mpc}$) cosmological simulations based on the FABLE galaxy formation model, varying the BLACK HOLE seed mass across the theoretical formation channels ($M_\mathrm{seed} = 10^{2}$-$10^{5} \, \mathrm{M_{\odot}}$), the accretion efficiency, including super-Eddington bursts, and the SUPERNOVA feedback strength. We forward-model observational selection with BALMERSOPICA, a mock JWST broad-line survey pipeline that assesses the detectability of each simulated AGN for a given grating and exposure time. We find that the bulk of the JWST AGN population can be assembled from any seed mass provided the accretion efficiency is high, although light seeds require the most favourable accretion conditions explored. Applying broad-line selection naturally recovers the apparently overmassive population, with the detected AGN lying furthest above the intrinsic $M_\mathrm{BH}$-$M_\mathrm{stellar}$ relation for inefficient accretion models. Notably, the selected AGN lie on the local, weakly evolving $M_\mathrm{BH}$-$σ_\mathrm{stellar}$ relation, supporting a scenario where BLACK HOLEs assemble before the stellar component is fully established. Since efficient accretion rapidly erases the imprint of the initial seed mass, the low-mass end of the BLACK HOLE mass function and host gas-phase metallicities offer the most promising discriminants between seeding channels.
[abstract 36 / 43] (score: 2) - Title: Quasi-static transverse electric field driven electron acceleration in RELATIVISTIC LASER matter interactionAuthors: Ameya Parab, Bhooshan Paradkar, Aparajit C., Anandam, Sk Rakeeb, Sagar Dam, Prashant Kumar Singh,Comments:Subjects: physics.plasm-phCreated: 2026-07-28; Updated: 2026-07-30; Datestamp: 2026-07-30
Achieving significant energy gain in LASER-driven RELATIVISTIC electron beams remains challenging due to dephasing between the accelerating LASER field and the electrons. We show that transverse electric fields, when aligned with the plane of LASER POLARIZATION, can mitigate dephasing and enable substantial energy gain without compromising beam directionality. As a practical realization, we propose a two-LASER scheme in which one LASER generates the transverse field while the other drives electron acceleration. By tailoring the interaction geometry, this configuration sustains phase locking, enhances energy transfer, and opens a pathway toward compact, high-efficiency electron accelerators.
[abstract 37 / 43] (score: 2) - Title: Dendro-GR at high mass ratios with high spinsAuthors: William K. Black, David W. Neilsen, Eric W. Hirschmann, David F. Van Komen,Comments: 18 pages, 18 figuresSubjects: gr-qc astro-ph.HECreated: 2026-07-29; Updated: 2026-07-30; Datestamp: 2026-07-30
The Laser Interferometer Space Antenna (LISA) launches in less than a decade; it will detect spinning high-mass-ratio binary BLACK HOLE inspirals annually, alongside other third-generation gravitational wave detectors. High-mass-ratio systems occupy a regime where numerical-relativity simulations remain computationally expensive and technically demanding, especially with high spins at precessing orientations. This portion of parameter space thus remains undersampled, leading to significant bias in parameter estimation. We must close these gaps. Here we report key progress in Dendro-GR toward reducing the computational cost of high-mass-ratio binaries with spin. We evolve the first Dendro-GR binaries at mass ratio $q=24$ (nonspinning) and at $q=12$ with spins up to $χ=0.8$ on both BLACK HOLEs, spanning various configurations. These proof-of-concept runs show strong evidence that Dendro-GR can simulate in this regime and beyond. The simulations generate accurate gravitational waveforms through multipole modes up to $\ell=8$, remain stable, keep constraint violations low and largely constant, conserve horizon mass, and have high computational efficiency with relatively low wall-hour cost. These results establish our starting line for systematic exploration of the high-mass-ratio, high-spin binary BLACK HOLE systems that are needed for gravitational wave analysis.
[abstract 38 / 43] (score: 2) - Title: No way ou$τ$: Epoch of Reionization Observations Do not Support Large Values of the Optical Depth to ReionizationAuthors: Paulo Montero-Camacho, Yi Mao,Comments: Comments welcome! 8 pages, 5 figuresSubjects: astro-ph.COCreated: 2026-07-29; Updated: 2026-07-30; Datestamp: 2026-07-30
Recent cosmological analyses combining high-redshift cosmic microwave background (CMB) measurements with low-redshift baryon acoustic oscillation (BAO) data have reported a preference for dynamical DARK ENERGY, with the cosmological constant scenario ($Λ$CDM) disfavored at the $\sim 3σ$ level. These analyses, however, typically rely on large-scale CMB POLARIZATION measurements to constrain the optical depth to reionization $τ_{\rm reio}\sim 0.06$, raising the question of whether potential systematics in this dataset could influence the inferred cosmological preference. Excluding large-scale POLARIZATION data substantially weakens the tension with $Λ$CDM to the $\lesssim 2σ$ level, nevertheless at a price of increasing $τ_{\rm reio}$ significantly to $\sim 0.09$. Here, we use a physically motivated Gompertzian reionization framework to perform a self-consistent Bayesian analysis combining CMB (excluding large-scale POLARIZATION data), BAO, and independent measurements of the neutral hydrogen fraction evolution from QUASAR damping wing observations and dark pixel constraints. We derive $τ_{\rm reio} = 0.067 \pm 0.011$, in good agreement with cosmological analyses that would include large-scale CMB POLARIZATION data, while the inferred reionization history is consistent with multiple observational constraints. Our analysis recovers a preference for dynamical DARK ENERGY at the $\gtrapprox2σ$ level. These results demonstrate that astrophysical probes of reionization independently recover the optical depth required by CMB POLARIZATION measurements, suggesting that potential systematics in large-scale POLARIZATION alone are unlikely to fully explain the emerging preference for dynamical DARK ENERGY.
[abstract 39 / 43] (score: 2) - Title: Probing the Physics of the Solar Corona with High-Resolution Observations using SKA-MidAuthors: Mark C. M. Cheung, John S. Morgan, Rohit Sharma, Sven Wedemeyer, Gregory Fleishman, Matthias Rempel,Comments: Published in Advancing Astrophysics with the SKAII (AASKAII), 2026(arXiv:2606.20366). Report-no:AASKAII/Cheung01. Advancing Astrophysics with the SKAII (AASKAII) outlines the transformative scientific advances that will be enabled by the SKA telescopesSubjects: astro-ph.SR astro-ph.IMCreated: 2026-07-29; Updated: 2026-07-30; Datestamp: 2026-07-30
We examine the capability of the SKA-Mid telescope for probing solar coronal structure and evolution. Using radiative MAGNETohydrodynamics simulations of a solar flare, we synthesise radio emission in bands available to SKA-Mid. SKA-Mid observations would provide important constraints on plasma processes that are important to diverse astrophysical environments, including flares/eruptions, MAGNETic RECONNECTion, particle acceleration, and gyro-emission processes. Observations with the AA4 configuration would reveal fine-scale structures in the solar atmosphere, making SKA-Mid a complementary telescope to other high resolution solar observatories operating at optical, infrared, and XUV wavelengths. Estimates of coronal scattering suggest that angular broadening rather than instrumental resolution (0.1'' at 10 GHz) will limit the detection of the finest structure under typical conditions. The extent of angular broadening depends on the nature of turbulence in the corona, and the longer baselines of SKA-Mid will serve to provide new observational constraints on coronal structure.
[abstract 40 / 43] (score: 2) - Title: Kinetic Optimization of Magnetic Mirror Confinement: Beyond Classical Loss-Cone TheoryAuthors: Lukas Einkemmer, Martin Guerra, Qin Li, Leonardo Zepeda-Núñez,Comments: 24 pages, 15 figuresSubjects: physics.plasm-ph math.OCCreated: 2026-07-29; Updated: 2026-07-30; Datestamp: 2026-07-30
Magnetic mirrors are among the conceptually simplest plasma confinement configurations and remain promising candidates for thermonuclear fusion. Their design requires shaping an externally applied MAGNETic field to confine plasma within an open-ended cylindrical device. In contrast to toroidally closed devices such as tokamaks and stellarators, confinement in MAGNETic mirrors depends intrinsically on kinetic mechanisms, particularly velocity-space trapping and particle loss through the open ends. We formulate MAGNETic mirror design as a PDE-constrained optimization problem governed by a reduced multispecies drift-kinetic-Poisson model. The resulting optimization reveals two physical effects not captured by the classical loss-cone argument. First, the self-consistent electric field generated through Poisson coupling acts as a secondary confinement barrier and substantially alters particle retention in the nonlinear regime. Second, the optimized MAGNETic-field configuration depends qualitatively on the underlying kinetic model: an electron-only model favors an unconventional centrally peaked field, whereas the fully coupled electron-ion model recovers the classical boundary-peaked mirror configuration. These results demonstrate that optimal MAGNETic mirror design cannot be determined solely from loss-cone considerations, but must account for the self-consistent nonlinear kinetic dynamics of the plasma.
[abstract 41 / 43] (score: 2) - Title: Energetic Particle Acceleration and Transport: Interplanetary Coronal Mass Ejections and ShocksAuthors: Olga E. Malandraki, Christina M. S. Cohen, Joe Giacalone, Leng Ying Khoo, Domenico Trotta, Laura Rodriguez-Garcia, Athanasios Kouloumvakos, Zheyi Ding, Yuncong Li, Alexander Kollhoff, John G. Mitchell, David J. Mccomas, Nathan A. Schwadron, Javier Rodriguez-Pacheco, Robert F. Wimmer-Schweingruber, George C. Ho, Glenn Mason, Michalis Karavolos, Jingnan Guo,Comments:Subjects: astro-ph.SRCreated: 2026-07-29; Updated: 2026-07-30; Datestamp: 2026-07-30
Solar Energetic Particles from suprathermal (few keV) up to RELATIVISTIC (few GeV) energies constitute an important contributor to the characterization of the space environment. Emitted from the Sun they are associated with solar flares and shock waves driven by Coronal Mass Ejections. This review presents important recent results of the study of Interplanetary CMEs and shocks in relation to energetic particle acceleration and transport, taking advantage of multi-point, multi-instrument observations available by a fleet of spacecraft in the heliosphere. In particular, the Solar Orbiter and Parker Solar Probe pioneering missions providing unprecedented measurements of energetic particles in the near-Sun environment offer promising insights into several unresolved questions particularly regarding the mechanisms responsible for the acceleration and transport of energetic particles in the heliosphere and their relative contributions.
[abstract 42 / 43] (score: 2) - Title: Outflow Behavior from the Transonic Advective Disks: A Hydrodynamical Simulation StudyAuthors: Sanjit Denath, Indranil Chattopadhyay, Raj Kishor Joshi, Philippe Laurent, Priyesh Kumar Tripathi, M. Saleem Khan,Comments: 12 pages, 4 figures, Proceedings of BINA conference in November 2025Subjects: astro-ph.HECreated: 2026-07-29; Updated: 2026-07-30; Datestamp: 2026-07-30
We investigate the properties of outflows from the transonic advective accretion disk using hydrodynamical numerical simulations. We consider two different disk temperatures with an order-of-magnitude difference. For the hotter disk, we adopt initial conditions for velocity, specific angular momentum, and temperature from analytical solutions. In the colder disk case, the velocity and angular momentum profiles are kept identical, while an order of magnitude reduction in the temperature. The simulations are performed in the presence of viscosity and radiative cooling, considering bremsstrahlung and SYNCHROTRON processes. In both disk models, the outflow rate increases with viscosity. We also examine the poloidal velocity structures for both cases. We analyze the influence of viscosity on the mass flux-weighted energy and momentum fluxes of the outflows. Our results show that both energy and momentum fluxes increase with higher viscosity and may play a significant role in accretion feedback mechanisms.
[abstract 43 / 43] (score: 2) - Title: Braking indices as probes of r-mode spin-down in young pulsarsAuthors: Shahram Abbassi, Armin Memarian, Evelyn Sophia Guest, S. R. Valluri,Comments: 14 pages, 7 figures, Accepted for publication in Journal of High-Energy AstrophysicsSubjects: astro-ph.HECreated: 2026-07-29; Updated: 2026-07-30; Datestamp: 2026-07-30
We present a timing-based framework for interpreting braking-index measurements in young pulsars using a four-channel spin-down model that includes particle-wind, MAGNETic-dipole, mass-quadrupole, and current-quadrupole torques. The observed braking index is a torque-weighted average of the channel exponents, enabling equation-of-state-independent constraints on the torque fraction of a possible r-mode-like current-quadrupole component from timing data alone. For positive, slowly varying secular torques, the allowed range is (1\le n_{\rm obs}\le 7), with (f_{7,\min}=\max[0,(n_{\rm obs}-5)/2]) and (f_{7,\max}^{\rm phys}=\min{1,\max[0,(n_{\rm obs}-1)/6]}). These bounds rely on non-negative, slowly evolving torque coefficients; if these assumptions fail, a large braking index need not uniquely indicate a current-quadrupole torque. Applied to young pulsars with measured braking indices, the analysis shows that most sources do not require gravitational-wave spin-down and are consistent with wind-plus-dipole braking. Sources with (3
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