Current date: 2026-11-04
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Number of records retrieved: 923
Keyword score statistics
score 12 -- 1 abstracts
score 11 -- 2 abstracts
score 8 -- 1 abstracts
score 7 -- 2 abstracts
score 6 -- 2 abstracts
score 5 -- 3 abstracts
score 4 -- 2 abstracts
score 3 -- 11 abstracts
score 2 -- 29 abstracts
in total -- 53 abstracts
Articles that appeared on 2026-11-04
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[abstract 1 / 53] Wow! (score: 12)
- Title: ElectroMAGNETic signatures of gradual MAGNETic dissipation in JETs from supermassive BLACK HOLEsAuthors: Stavros Dimitrakoudis, Maria Petropoulou, Stamatios I. Stathopoulos, Dimitrios Giannios,Comments: 15 pages, 16 figures, submitted to A&ASubjects: astro-ph.HECreated: 2026-11-03; Updated: 2026-11-04; Datestamp: 2026-11-04
Context. Blazar JETs -- collimated and RELATIVISTIC plasma outflows viewed at small angles -- are prolific sources of non-thermal radiation. Aims. We develop a numerical framework for calculating the emission from an extended BLAZAR JET where gradual energy dissipation, mediated through MAGNETic RECONNECTion, takes place across a wide range of distances from the supermassive BLACK HOLE. Methods. We adapt the open-source radiative transfer code LeHaMoC that self-consistently calculates photon spectra from RELATIVISTIC charged particles that occupy a spherical blob to treat the emission from an extended JET. The JET is treated as a series of segments that interact with each other through radiative transfer. The effects of radiation spillage are calculated iteratively throughout the JET, accounting for RELATIVISTIC effects arising from the relative motion between JET segments, until a steady state is reached. Results. We find that this approach produces some distinct differences in the total spectral energy distribution compared to the results obtained by adding the emission escaping from each constituent segment of the JET (optical thin regime), increasing the part of the spectrum affected by inverse Compton scattering by a factor of three. However, the latter is always far less luminous than the SYNCHROTRON component, even when enhanced by external radiation fields. Conclusions. Gradual MAGNETic dissipation in JETs from supermassive BLACK HOLEs leads to nearly universal, SYNCHROTRON-dominated photon spectra. The numerical framework developed here is readily adaptable to a broad range of JET dissipation scenarios and applications to extended JET emission.
[abstract 2 / 53] Wow! (score: 11) - Title: Reconnection-driven Plasma Loading for Prompt Emission in Tidal Disruption Event JetsAuthors: Rin Oikawa, Yuri Sato,Comments: 12 pages, 4 figures, ApJL, 1011, L12 (2026)Subjects: astro-ph.HECreated: 2026-11-03; Updated: 2026-11-04; Datestamp: 2026-11-04
A tidal disruption event (TDE) occurs when a star passes sufficiently close to a BLACK HOLE (BH) to be disrupted by its tidal forces. Although several hundred TDEs have been identified to date, only a small fraction launch RELATIVISTIC JETs. These JETs are thought to be Poynting-flux-dominated outflows powered by the Blandford-Znajek (BZ) mechanism. However, the origin of the JET plasma required to account for the observed prompt emission remains poorly understood and constitutes a key unresolved problem in the formation of RELATIVISTIC TDE JETs. In this Letter, we propose MAGNETic RECONNECTion near the BH as a physical mechanism for injecting plasma into the BZ JET during the super-Eddington accretion phase. Once sufficient MAGNETic flux accumulates near the BH, an equatorial current sheet forms, in which MAGNETic RECONNECTion produces high-energy gamma rays. We demonstrate that photon-photon interactions generate a sufficient particle supply to account for the observed prompt emission. We further show that our plasma loading scenario allows the JET to remain MAGNETically dominated out to the prompt emission region and that MAGNETic dissipation can consistently reproduce the observed prompt emission properties. Furthermore, our scenario predicts MeV and GeV gamma-ray flares, providing a direct means of testing this scenario with future gamma-ray observatories.
[abstract 3 / 53] Wow! (score: 11) - Title: XMM-Newton and NUSTAR quasi-simultaneous follow-up of the very high energy flare of PKS~1725+123 in August 2025Authors: L. Marcotulli, A. Gokus, L. Heckmann, E. Visentin, I. Jaroschewski, J. Otero-Santos, M. Böttcher, M. Zacharias, R. Takeishi, S. Nozaki, Y. Suda, I. Sadeh, P. Boorman, E. de Oña Wilhelmi, D. Berge,Comments: Submitted to A&A; 12 pages, 8 Figures, 4 TablesSubjects: astro-ph.HECreated: 2026-11-02; Updated: 2026-11-04; Datestamp: 2026-11-04
We report the results of the spectral timing analysis of the quasi-simultaneous X-ray follow-up with XMM-Newton ($50\,\rm ks$) and NUSTAR ($180\,\rm ks$) of the very high energy flare of the BLAZAR PKS 1725+123 ($z=0.586$) in August of 2025. The X-ray monitoring started $\sim3$ days after the announcement of the VHE flare by LST-1, MAGIC and H.E.S.S. and lasted for almost 5 days. The high sensitivity of XMM-Newton reveals two spectral components, a soft ($Γ_{\rm X}>2$) and a hard ($Γ_{\rm X}<2$) power law. While the soft component dominates at $E<2\,\rm keV$, the hard component dominates at $E>2\,\rm keV$, likely marking the transition between the SYNCHROTRON and the high-energy emission, the "valley" of this BLAZAR's spectral energy distribution. Within the XMM-Newton pointing ($\sim14$ hours) we witness the shift of the SYNCHROTRON component out of the X-ray band. In the following $\sim 4$ days, NUSTAR further reveals the brightening by a factor of 1.5 of the hard component, following the shift of the high-energy part of the SED into the X-ray band. Overall, within a week (observed frame) of the VHE flare, PKS 1725+123 went from temporarily being an intermediate SYNCHROTRON peaked BLAZAR to transitioning back to its `normal' state of a low SYNCHROTRON peaked one. This is the first time that the evolution of a VHE flare from a BLAZAR JET has been followed continuously in X-rays over such an extended period and our results highlight the importance of long-term quasi-simultaneous X-ray follow-up of VHE BLAZAR flares.
[abstract 4 / 53] Wow! (score: 8) - Title: Radiative RELATIVISTIC RECONNECTion powering the hard-state emission of X-ray binaries: SYNCHROTRON-driven pair loading, MeV tail, and seed photonsAuthors: Valeriia Rohoza, Maria Petropoulou, Hayk Hakobyan, Despina Karavola, Lorenzo Sironi,Comments: Submitted to ApJ; comments are welcome. 17 pages, 9 figuresSubjects: astro-ph.HECreated: 2026-11-03; Updated: 2026-11-04; Datestamp: 2026-11-04
In the hard state, X-ray emission from BLACK HOLE X-ray binaries is attributed to Comptonization in the corona, a highly MAGNETized region near the BLACK HOLE. Relativistic MAGNETic RECONNECTion drives bulk motions that can upscatter soft photons and reproduce the spectral peak at $\sim 100$ keV for parameters relevant to Cygnus X-1. However, the origin of the seed photons and of the MeV tail above the peak remains unclear. In 3D RECONNECTion, so-called "free" particles escape the flux ropes and accelerate at the maximum rate set by the RECONNECTion electric field. Their SYNCHROTRON emission extends to tens of MeV, which enables $γγ$ pair production with the Compton-upscattered photons. We present 3D particle-in-cell simulations of RELATIVISTIC RECONNECTion in pair plasma, in which particles cool by inverse Compton (IC) scattering below the SYNCHROTRON self-absorption threshold and by SYNCHROTRON radiation above it. Of the incoming MAGNETic power, $\sim 40 \%$ is converted to IC radiation and $\gtrsim 10$-$20\%$ to SYNCHROTRON. Using analytical estimates and radiative calculations for Cygnus X-1, we model how the radiation from RECONNECTion-accelerated particles is reprocessed in the corona. Pair production attenuates the SYNCHROTRON emission above $\sim 1$ MeV, and the escaping $γ$-rays form an MeV tail consistent with the observations, extending up to at least $\sim 10$ MeV. Most of the absorbed power goes into secondary pairs, whose Thomson optical depth can reach order unity. Their SYNCHROTRON emission, peaking at $\sim 0.1 \, \text{keV}$, can supply the seed photons for Comptonization. Our results support RECONNECTion-based SYNCHROTRON self-Compton models of the hard-state emission in X-ray binaries.
[abstract 5 / 53] Wow! (score: 7) - Title: 2:1 Harmonics in the Radio Light Curves of Supermassive Black Hole Binary CandidatesAuthors: A. C. S. Readhead, M. F. Aller, R. D. Blandford, T. Surti, P. V. De la Parra, A. G. Sullivan, P. Mróz, N. Murray, M. C. Begelman, B. Molina, M. L. Lister, E. R. Most, S. O'Neill, V. A. Diamantopoulos, N. Globus, T. Hovatta, I. Liodakis, T. J. Pearson, S. E. Tremblay,Comments: 21 pages, 7 figures, 6 tables, submitted to ApJSubjects: astro-ph.HECreated: 2026-11-03; Updated: 2026-11-04; Datestamp: 2026-11-04
We present evidence of 2:1 harmonic periodicities in two supermassive BLACK HOLE binary (SMBHB) candidates (PKS J0805-0111 and PKS 2131-021) in the Owens Valley Radio Observatory (OVRO) + University of Michigan Radio Astronomical Observatory (UMRAO) monitoring programs. This potential discovery follows the previous detection of a 2:1 harmonic periodicity in the SMBHB candidate J1309+1154 from these programs. If confirmed, these suggest a physical origin of BLAZARs exhibiting strong periodicities favoring 2:1 commensurabilities in their light curves. There are significant differences between the 2:1 harmonics in these three BLAZARs, which may be due to differences in their central engines. These three SMBHB candidates demonstrate the importance of careful dissection, i.e. cutting apart and close examination, of BLAZAR light curves, to reveal underlying evidence of coherence between different aspects of the periodicities observed in BLAZARs in the presence of correlated random noise variations. This is particularly important for BLAZAR SMBHB searches, given that the observed periods thus far are all longer than 2 years, and can disappear for long timespans. Harmonics may therefore be crucial in confirming the reality of periodicities and identifying BLAZAR SMBHB candidates. We discuss four models that can account for 2:1 commensurable periodicities in BLAZAR light curves and explain how future detections of shorter period SMBHB candidates, or the lack thereof, may be used to discriminate among the models. Arguments for and against the reality of these periodicities are presented.
[abstract 6 / 53] Wow! (score: 7) - Title: H 0557$-$385: A Candidate Missing Link Between Radio-Quiet Seyferts and Young Radio GalaxiesAuthors: J. Chauhan, T. D. Russell, A. Lohfink, M. Bottcher, F. Panessa, R. L. C. Starling, K. Nyland, C. Done, S. Chattopadhyay, T. Ghosh, R. Misra, M. Del Santo,Comments: Accepted for publication in MNRASSubjects: astro-ph.GA astro-ph.HECreated: 2026-11-02; Updated: 2026-11-04; Datestamp: 2026-11-04
The Seyfert 1 galaxy H 0557$-$385 (z = 0.034) has long been classified as radio-quiet on the basis of its radio-to-optical flux ratio, yet its radio properties are physically inconsistent with this designation. We present a broadband ($0.076 - 258.8$ GHz) radio spectral analysis combining new Australia Telescope Compact Array (ATCA) observations with archival Murchison Widefield Array (MWA), Australian Square Kilometre Array Pathfinder (ASKAP) and Atacama Large Millimeter/submillimeter Array (ALMA) data. The spectrum requires a two-component model: a compact, self-absorbed component with a stratified gigahertz-peaked (GPS)/high-frequency-peaked (HFP) spectral shape (turnover at $9.4^{+0.6}_{-0.5}$ GHz), superposed on an extended, optically thin power-law lobe ($α_{\rm pl} = -0.78$) that dominates below ~1.6 GHz. The derived parameters $-$ a source size of ~15 pc, an equipartition MAGNETic field of 2.8 mG, a SYNCHROTRON age of $\lesssim1.8\times10^{3}$ yr, and a time-averaged JET power of ${\sim}5\times10^{41}$ $-$ $5\times10^{44}$ erg s$^{-1}$ $-$ are characteristic of compact steep-spectrum and GPS young RADIO GALAXies, not of canonical radio-quiet AGN. The two-component structure admits two interpretations that the present data cannot distinguish: the extended emission may be the growing lobe of a genuinely young, expanding RADIO GALAXy, or relic plasma from an earlier episode of a transient or recurrent JET. Under either, H 0557$-$385 is better understood as an intermediate object: optically a Seyfert, but with the radio-physical properties of a newly ignited or recently re-triggered RADIO GALAXy. It is therefore a candidate missing link between radio-quiet AGN and large-scale RADIO GALAXies. Distinguishing these scenarios will require high-resolution imaging and multi-epoch monitoring
[abstract 7 / 53] Yes (score: 6) - Title: The Late-time Afterglow of GW170817 and Implications for Jet DynamicsAuthors: Aman Katira, Kunal P. Mooley, Kenta Hotokezaka,Comments: 12 pages, 9 figures, Accepted for publication in MNRASSubjects: astro-ph.HECreated: 2026-11-03; Updated: 2026-11-04; Datestamp: 2026-11-04
GW170817 is the first binary neutron star merger detected with gravitational and electroMAGNETic waves, and its afterglow is still detectable 7 years post-merger. Some previous studies of the X-ray afterglow have claimed the onset of a new afterglow component or raised concerns about the data processing techniques. Motivated thus, we present here a reanalysis of X-ray afterglow data for GW170817 and find potential sources of discrepancies between the data reduction techniques employed by various research groups. We also analyze the updated panchromatic afterglow data to find that there is no significant evidence for any new afterglow component (e.g. due to the ejecta that gave rise to the kilonova) and that the JET must be still in a mildly RELATIVISTIC phase. The decline in the afterglow light curve is significantly shallower compared to that expected from the standard SYNCHROTRON afterglow JET models with sideways spreading, indicating either an additional energy injection at late times or the velocity dependence on the microphysics parameters. In this context, we discuss the implications of the late time afterglow data on JET dynamics.
[abstract 8 / 53] Yes (score: 6) - Title: How Fast do Black Holes Spin?Authors: Chen Yuan, Vitor Cardoso,Comments: 7 pages, 3 figuresSubjects: astro-ph.HE gr-qc hep-phCreated: 2026-11-03; Updated: 2026-11-04; Datestamp: 2026-11-04
We present a systematic study of the spin evolution of accreting BLACK HOLEs. Using the BHAC code for general RELATIVISTIC MAGNETohydrodynamic simulations, we conduct a total of 500 high resolution simulations of MAGNETized accretion disks around Kerr BHs with spin parameters ranging from $χ=0$ to $χ= 0.99$. The baseline configuration follows the default Fishbone--Moncrief torus setup in BHAC. We further explore the effects of: I) introducing multiple poloidal MAGNETic loops, II) the initial position of the torus, III) MAGNETic field strength and IV) radial loop modulation. From each simulation we extract the mass flux and angular momentum flux through the horizon to compute the time-averaged spin evolution rate after the system becomes quasi-stationary. The equilibrium spin ranges from $χ_{\rm eq}\simeq0.88$ in the fiducial model to $χ_{\rm eq}\simeq0.98$ for weak-flux model. Applied to Sgr A$^*$, even an optimistic estimate for rapid spin evolution gives a timescale longer than $10^{13}$ yr, indicating an earlier growth or merger history. These trends are consistent with the picture that larger net MAGNETic flux threading the horizon enhances JET-torques and reduces the equilibrium spins, whereas weak net flux yields near-maximal spins. Our results provide a pathway to interpret the high spins reported for X-ray binaries and ACTIVE GALACTIC NUCLEi and they sharpen the astrophysical viability of near-horizon high-energy processes that rely on near-extremal BLACK HOLEs.
[abstract 9 / 53] Yes (score: 5) - Title: Structure of energy flux densities in Earth's MAGNETotail RECONNECTion regions: Bridging simulation and observationAuthors: Cara L. Waters, Jonathan P. Eastwood, Harry C. Lewis, Naïs Fargette, Marit Øieroset, Tai D. Phan, David L. Newman, Martin V. Goldman,Comments: 25 pages, 3 figures, submitted to Geophysical Research Letters 3rd September 2026, revisions submitted 29th October 2026Subjects: physics.space-ph physics.plasm-phCreated: 2026-11-02; Updated: 2026-11-04; Datestamp: 2026-11-04
Magnetic RECONNECTion is important in both space and laboratory contexts because it changes the topology of MAGNETic fields and converts MAGNETic energy into particle energies. Establishing where this energy conversion occurs is critical for understanding how RECONNECTion partitions energy. Using a novel machine learning approach based on simulations that explicitly identifies the separatrix regions for the first time, the partition of energy flux densities within the MAGNETic RECONNECTion site is evaluated through statistical study of MAGNETotail RECONNECTion events observed in situ. The separatrices are found to have the largest electron energy flux densities, roughly twice those in the exhaust, and Poynting flux densities about four times those in the inflows, whereas typical ion enthalpy flux densities are largest in the exhaust. The separatrices are therefore sites of intense electron and electroMAGNETic energy transport, although their small thickness means that the exhaust may still carry most of the total energy flux.
[abstract 10 / 53] Yes (score: 5) - Title: SS 433 Eastern Jet Turbulence Revealed by Spatially-Resolved IXPE Data AnalysisAuthors: Ningyue Fan, Jack T. Dinsmore, Roger W. Romani,Comments: 10 pages, 4 figures and 1 table. Submitted to ApJ; revised versionSubjects: astro-ph.HECreated: 2026-11-02; Updated: 2026-11-04; Datestamp: 2026-11-04
The extended X-ray JET (EXJ) of SS 433/W50 shows hard X-ray and very-high-energy gamma-ray emission, indicating strong particle acceleration, likely sensitive to the EXJ MAGNETic field structure and turbulence. To study this field, we re-analyze the 2023 Imaging X-ray Polarimetry Explorer (IXPE) observation of the eastern EXJ using the publicly available POLARIZATION fitting package LeakageLib. Compared with standard PCUBE and spectropolarimetric analyses, this approach improves the POLARIZATION constraints and enables spatially resolved POLARIZATION measurements. Dividing the EXJ into head, spine, and sheath regions with independent POLARIZATION properties, we find significant (>3 sigma) improvement over a single-zone model. The sheath exhibits lower POLARIZATION than the head and spine, while the electric vector position angles are consistent across all regions, indicating MAGNETic fields aligned with the JET axis. The measurements imply enhanced MAGNETic turbulence at the JET boundary, potentially driven by Kelvin-Helmholtz instabilities.
[abstract 11 / 53] Yes (score: 5) - Title: FERMI-LAT Detection of Extended GeV Emission toward the Middle-aged Supernova Remnant G156.2+05.7Authors: Wei-Liang Xu, Qing-Wen Tang, Long Li,Comments: 11 pages, 8 figures, accepted for publication in MNRASSubjects: astro-ph.HECreated: 2026-11-03; Updated: 2026-11-04; Datestamp: 2026-11-04
We analyse 17 years of FERMI-LAT $γ$-ray data toward the middle-aged SUPERNOVA remnant (SNR) G156.2+05.7, supplemented by radio and CO observations and by published X-ray constraints. An extended $γ$-ray source is detected, well described by a 2D Gaussian template ($R_{68} \sim 0.84^\circ$). This description is preferred over a foreground CO template, whereas the Gaussian and a uniform disc are statistically indistinguishable under the AIC. The spectrum shows evidence for curvature, with a log-parabola preferred over a power law at the $\approx 3.4σ$ level. Multi-wavelength spectral energy distribution (SED) modelling, under the adopted assumptions, suggests a leptonic--hadronic joint scenario consistent with the data, with the FERMI-LAT spectrum favouring a hadronic contribution over a purely leptonic interpretation. However, the proton-dominated alternative remains competitive, so the partition of the GeV emission is model-dependent. In the adopted leptonic--hadronic model, the electron population accounts for the radio SYNCHROTRON emission and a leptonic $γ$-ray component, while a steep proton population contributes the remaining hadronic $γ$-rays. Adopting a reference distance $d = 2.7$ kpc, the fitted electron cutoff ($E_{e,\mathrm{cut}}\approx 1.2$ TeV) is compatible with the thermal-dominated X-ray emission, while the proton cutoff is fixed by assumption at $1$ TeV. The northeast and southwest quadrants show enhanced $γ$-ray emission, which may be related to a clumpy or asymmetric surrounding medium. A correspondence with the directions of optical H$α$ filaments is suggested by the quadrant orientation but is not yet established. No significant long-term flux variability is found, consistent with steady emission from an extended source.
[abstract 12 / 53] Yes (score: 4) - Title: Radiation Magnetohydrodynamic Simulation of sub-Eddington Circumbinary Disk in a 10:1 Massive Black Hole BinaryAuthors: Vishal Tiwari, Chi-Ho Chan, Tamara Bogdanović, Yan-Fei Jiang, Shane W. Davis,Comments: 17 pages, 8 figures. Published in ApJSubjects: astro-ph.HECreated: 2026-11-02; Updated: 2026-11-04; Datestamp: 2026-11-04
We present a global three-dimensional radiation MAGNETohydrodynamic (RMHD) simulation of a circumbinary disk (CBD) around a massive BLACK HOLE binary (MBHB) with a total mass $2 \times 10^7\,M_{\odot}$ and mass ratio $0.1$, separated by $100\, GM_{\rm tot}/c^2$. The inclusion of radiation makes the disk thinner, denser, less eccentric at the inner edge, and more filamentary when compared to an otherwise identical locally isothermal MHD disk. The RMHD disk has accretion rate $\sim 0.23\,\dot{M}_{\mathrm{Edd}}$ and produces thermal emission peaking in the near-UV/optical with a luminosity of $\sim 1\, \% L_{\rm {Edd }}$. Compared with an equal-mass binary with the same total mass, the thermal emission of the CBD around the unequal-mass binary is several orders of magnitude brighter and much more variable at far-UV/soft X-rays frequencies. Similarly, we find that the light curve associated with the $0.1$ mass ratio binary exhibits dominant periodicity corresponding to 2 binary orbits, compared to the equal-mass binary that shows periodicity at 2.5-5 binary orbits. Our results highlight the importance of radiation for the structure and observational properties of MBHB circumbinary disks and have implications for detecting electroMAGNETic counterparts to LISA gravitational wave precursors and for the heavier binaries targeted by the Pulsar Timing Arrays.
[abstract 13 / 53] Yes (score: 4) - Title: Modeling runaway electron mitigation via passively driven plasma instabilities in a high-current tokamakAuthors: R Datta, C Clauser, G Hu, A Braun, N Ferraro, R Sweeney, A Tinguely and,Comments:Subjects: physics.plasm-phCreated: 2026-11-03; Updated: 2026-11-04; Datestamp: 2026-11-04
A critical challenge for tokamak-based fusion power plants is the formation of high-current, RELATIVISTIC runaway electron (RE) beams during abrupt confinement loss events called disruptions. RE beams may significantly damage machine components if left unmitigated, jeopardizing the operational and economic viability of fusion power plants. We present the first self-consistent extended MAGNETohydrodynamic (MHD) computational study of RE mitigation with a passively driven RE mitigation coil (REMC) in a high-current tokamak. RE generation and transport are coupled with REMC-driven MHD activity in a 3D simulation that models the thermal and current quench phases of a mid-plane disruption, together with the vertical displacement and final termination of the plasma and RE beam on SPARC -- a high-field, high-current tokamak designed to achieve a fusion gain Q > 1. We demonstrate that REMC-driven MAGNETic stochasticity can reduce the RE current by over an order-of-magnitude when compared to unmitigated disruptions. The final termination is mediated via a post-thermal-quench "cold" vertical displacement of the plasma, which, together with MAGNETic stochasticity, increases RE losses via scrape-off once the plasma contacts the first wall. These results demonstrate a viable mechanism for RE mitigation using passively driven plasma instabilities on high-current tokamaks.
[abstract 14 / 53] (score: 3) - Title: Second-scale periodicity in FRB 20201124A: coincident with critical RM evolution epochs and its possible implicationsAuthors: Wen-Long Zhang, Chen-Ran Hu, Chen Du, Zhen-Yin Zhao, Wang-Chen Xue, Wen-Jun Tan, Shuang-Xi Yi, Shao-Lin Xiong, Fa-Yin Wang, Li-Ming Song, Cheng-Kui Li, Shuang-Nan Zhang, Chen-Wei Wang, Sheng-Lun Xie, Xiao-Fei Dong, Yong-Feng Huang,Comments: 9 pages, 7 figures. Accepted for publication in A&ASubjects: astro-ph.HECreated: 2026-11-03; Updated: 2026-11-04; Datestamp: 2026-11-04
Second-timescale periodicity ($\sim$1.7\,s) has been reported in the repeating fast radio burst FRB\,20201124A during two epochs, MJD\,59310 and MJD\,59347. We find that these two epochs coincide with the days on which the Faraday rotation measure (RM) of the source passes through the transition between the quasi-steady and the strongly varying phases that are predicted by the MAGNETar/Be-star binary model. To examine whether this coincidence could arise by chance, we re-fitted the secular RM evolution within the same binary framework and estimated the probability of chance coincidence, $P_{\rm CC}\approx2.5\%$. Independently, and in order to cross-validate the reported periodicity, we carried out a coherent joint period search on the bursts of the two epochs, assuming a simple linear evolution of the spin period; we obtain $P_0=1.70603$\,s and $\dot{P}=6.1\times10^{-10}$\,s\,s$^{-1}$ at the reference epoch, with a Gaussian significance of $\sim3.9σ$, consistent with the previous measurement. We propose that the two periodic epochs correspond to passages of the MAGNETar through the decretion disk of the Be-star companion. The captured disk material suppresses low-latitude MAGNETospheric emission, so that the polar-cap emission dominates and the spin period becomes detectable; alternatively, because the disk material carries substantial angular momentum, accretion increases the MAGNETic obliquity and thereby amplifies the periodic modulation of the polar-cap emission. The synchronization between the burst periodicity and the MAGNETo-ionic transition points to a link between burst activity and the dynamical evolution of the source environment. The details of the binary-model fit and of the period search are given in Appendices A and B.
[abstract 15 / 53] (score: 3) - Title: Parity-dependent wave absorption and optical characteristics of a cored MAGNETic BLACK HOLEAuthors: Mohsen Fathi, Faizuddin Ahmed,Comments: 22 pages, 9 figures, 17 tables. Substantially revised and expanded manuscript, with improved analytical and numerical results, updated references, and corrected table and figure cross-references. The presentation and page layout have also been improvedSubjects: gr-qc astro-ph.HECreated: 2026-11-03; Updated: 2026-11-04; Datestamp: 2026-11-04
We study light propagation and coupled gravitational--electroMAGNETic waves around a BLACK HOLE supported by a nonlinear MAGNETic field. The same field action fixes the geometry, the mass--charge relation, and the wave potentials. We calculate two critical impact parameters for light and solve the coupled scattering equations in both parity sectors. In eight solutions of one action, the two optical scales differ by $3.6$--$7.2\%$. The wave absorption also depends on parity. For $\ell=2$, the gap between the larger absorption eigenvalues reaches about $9.0$ percentage points. A wider frequency scan reveals a stronger effect in the second eigenchannel. The difference between the two absorption traces reaches $24.3$ percentage points. The trace equals twice the absorption of an equal incoherent mixture of incoming gravitational and electroMAGNETic fields. A controlled test of the wave operator shows that the nonlinear electroMAGNETic factor $κ$ plays an important role in the parity gap. We also examine four $\ell=3$ cases and use charge-matched Reissner--Nordström BLACK HOLEs as a separate control. The optical and wave calculations provide two complementary properties of the same MAGNETic source.
[abstract 16 / 53] (score: 3) - 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: Accepted for publication in MNRAS; 32 pages, 15 figuresSubjects: astro-ph.GA astro-ph.HECreated: 2026-11-03; Updated: 2026-11-04; Datestamp: 2026-11-04
The ACTIVE GALACTIC NUCLEi (AGN) 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, represent the observable tail of a broader population, or reflect systematic uncertainties in mass estimates. We introduce the AESOPICA project, a suite of twelve mid-volume ($L = 60\,\mathrm{cMpc}$) 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. 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 17 / 53] (score: 3) - Title: Relativistic hydrodynamics of a charged fluid from Myers-Pospelov Lorentz-Violating ElectrodynamicsAuthors: Matheus Duarte, Vitor de Souza,Comments:Subjects: astro-ph.HECreated: 2026-11-03; Updated: 2026-11-04; Datestamp: 2026-11-04
We derive the equations of RELATIVISTIC hydrodynamics for a charged fluid from Lorentz-violating Myers--Pospelov electrodynamics. Starting from the modified fermionic and electroMAGNETic equations of motion, we employ the covariant Wigner formalism to establish the semiclassical spectral constraints and distribution function, which, combined with Noether's theorem, yield the energy-momentum tensor, particle current, and corresponding conservation laws in the presence of Lorentz violation. The resulting hydrodynamic description contains Lorentz-violating corrections to the thermodynamic quantities and to the fluid currents. In the purely timelike sector, these corrections can be absorbed into effective thermodynamic quantities, preserving the isotropic structure of the fluid equations. In contrast, spacelike backgrounds introduce explicit contributions along the preferred direction, which cannot be absorbed into the standard hydrodynamic variables and give rise to anisotropic forces and torques. These effects lead to departures from standard RELATIVISTIC charged-fluid hydrodynamics and provide a direct macroscopic manifestation of the Lorentz-violating background. Our results establish a first-principles framework for investigating the macroscopic consequences of Lorentz violation in RELATIVISTIC charged fluids and provide a starting point for the development of a consistent Lorentz-violating RELATIVISTIC MAGNETohydrodynamic theory.
[abstract 18 / 53] (score: 3) - Title: Jets and winds from the most powerful compact object in NGC 5408Authors: Roberto Soria, Manfred W. Pakull, Christian Motch, Thomas D. Russell, Fabien Grisé,Comments: 25 pages, 5 MB. Accepted by A&ASubjects: astro-ph.HE astro-ph.GACreated: 2026-11-02; Updated: 2026-11-04; Datestamp: 2026-11-04
Super-critical accretion onto stellar-mass compact objects is sometimes revealed by ultraluminous X-ray sources (ULXs). In other cases, X-rays are heavily obscured along our line of sight, but a super-Eddington accretion power can be indirectly revealed by multiband studies. We have identified a candidate super-critical source in NGC 5408 (labelled X-2). We argue that: it is powered by accretion; it is among the most powerful in the local universe, despite its apparent X-ray faintness; it has exceptional optical properties (both in the continuum and in the lines). We carried out a multiband imaging and spectral study with the ATCA, the VLA, HST, the VLT and Chandra. We found an unresolved source with: variable radio emission (5-GHz luminosity of a few x 10^{35} erg/s); red optical continuum with absolute mag M_{V,0} = -9.1, M_{I,0} = -10.6; exceptionally broad low-ionization emission lines (FWHM ~ 1700 km/s) with P-Cygni profiles; narrow, photoionized emission lines including strong He II 4686; point-like hard X-rays; marginally resolved soft X-rays. We also found an ~20-pc He^{++} nebula near X-2, associated with candidate Wolf-Rayet stars. The optical continuum declined by 2 mag between 2010 and 2024, as did the intensity of broad and narrow lines. We argue that the system is powered by the radiative and mechanical output of a super-Eddington stellar mass BH, with an accretion power >~10^{40} erg/s. We propose that X-2 is a Compton-thick ULX seen at high inclination, with a flaring JET and X-ray emission emerging from the polar funnel. We argue that the optical continuum and the broad emission lines are signatures of an optically thick outflow, launched either from the accretion disk, or from an LBV-like donor star, or, more speculatively, caused by the elusive phase of common envelope ejection. We suggest that we are looking at a short-lived phase of hyper-Eddington accretion.
[abstract 19 / 53] (score: 3) - Title: Evidence for strong shocks in the ISM of small radio sourcesAuthors: Valeria Lopez, Mark Lacy,Comments: To appear in ApJ Letters. Link to data in Zenodo: 10.5281/zenodo.23326653Subjects: astro-ph.GACreated: 2026-11-02; Updated: 2026-11-04; Datestamp: 2026-11-04
Radio JETs deposit energy into the interstellar medium of their host galaxies, and while a JET is still confined within the host it is expected to drive shocks through the gas. Broad [OIII] 5007 profiles trace ionized gas that has been disturbed, the [OI]/H-alpha versus [OIII]/H-beta diagram helps distinguish gas photoionized by an AGN from gas excited by shocks, and the high ionization [NeV] 3426 line traces the hard UV continuum of the accretion disk, which shocks only reproduce at very high velocities. We have selected two samples of radio-loud AGN from a cross-match of the VLA Sky Survey with DESI Data Release 1, at 0.15 < z < 0.5 and with [OI] 6300 detected at > 5-sigma: one with projected radio sizes of 10-15 kpc, whose JETs are still inside the host, and one with sizes greater than 25 kpc, whose JETs have broken out. We fit the [OIII] and [OI] profiles, measure W80, and classify each source on the BPT diagram. The confined sources have broader [OIII] lines, sit systematically closer to the LINER region, and are detected less often in [NeV], and the [NeV] difference is not explained by redshift or dust. The broad components are not systematically blueshifted, so the confined sources are distinguished by line width rather than by outflow velocity. We then discuss how these results indicate that the JETs of the confined sources are driving strong shocks through the interstellar medium of their hosts.
[abstract 20 / 53] (score: 3) - Title: Dynamics of Vortex Electrons in a Uniform Magnetic Field Across NonRELATIVISTIC and Relativistic RegimesAuthors: Yujian Lin, Zhigang Bu, Shiyu Liu, Taoming Guo, Liangliang Ji,Comments:Subjects: physics.plasm-phCreated: 2026-11-03; Updated: 2026-11-04; Datestamp: 2026-11-04
The dynamics of a vortex electron in a transverse uniform MAGNETic field involves not only the cyclotron motion of the wave packet center but also the evolution of its internal wavefunction structure. To study this process, we develop a quantum framework and investigate the dynamics of vortex electrons in both the nonRELATIVISTIC and RELATIVISTIC regimes. A discrete Bessel-Gaussian initial wave packet is expanded in the basis of Dirac eigenstates to obtain the time-dependent wavefunction and to analyze its spatiotemporal evolution. In the nonRELATIVISTIC regime, the results deviate significantly from the rigid point-dipole model, as the intrinsic kinetic orbital angular momentum exhibits dynamics more complex than simple Larmor precession, owing to the nonstationary internal current distribution of the wave packet. In the RELATIVISTIC regime, the nonlinear dependence of the energy levels on the quantum numbers destroys the equal spacing of the spectrum. Consequently, the relative phases among the eigenstate components of the wave packet evolve nonuniformly, resulting in wave-packet spreading and deformation, accompanied by modified intrinsic orbital angular momentum dynamics. We introduce a dimensionless parameter to quantify this RELATIVISTIC dephasing, providing an approximate criterion for selecting physical parameters and evolution times to mitigate the resulting wave-packet distortion. These results clarify the limitations of the rigid point-dipole model, highlight the essential role of internal wavefunction structure, and provide theoretical guidance for understanding and manipulating RELATIVISTIC vortex electrons.
[abstract 21 / 53] (score: 3) - Title: Extreme Multiwavelength Variability in the Recurrent Intermediate-type Changing-look Seyfert Galaxy SDSS J234728.73+242745.7Authors: Jiahua Wu, Liming Dou, Yanli Ai, Jianguo Wang, Tinggui Wang, Huaqing Cheng, Chichuan Jin, Luis C. Ho, Qiming Wu, Kovi Rose, Roberto Soria, Alexis Coleiro, Junhui Fan, Yuan Liu, Dongyue Li, Zhen Zhang, Yunfei Xu,Comments: Accepted for publication in ApJSubjects: astro-ph.HE astro-ph.GACreated: 2026-11-03; Updated: 2026-11-04; Datestamp: 2026-11-04
We report the discovery of the Seyfert galaxy J234728.73+242745.7 as a recurrent intermediate-type CLAGN with extreme optical/UV variability. Optical spectra spanning nearly three decades reveal Type 1.0$\rightarrow$1.5$\rightarrow$1.2 transitions, accompanied by the disappearance and reappearance of broad He II $\lambda4686$ and a broad-line Balmer decrement evolving from 4.5 to 7.2 and then 2.4. Monitoring reveals coordinated variability from X-rays to the MIR. SED decomposition yields a host-corrected g-band high-to-low-state flux ratio of $5.4\pm0.4$, exceeding the SWIFT/XRT ratio of $2.7\pm0.8$ across the changing-look transition. This discrepancy may arise from reduced dust extinction, as correcting for the low-state continuum reddening ($A_V^{\rm cont}=0.66\pm0.23$ mag) brings the optical/UV ratios close to the X-ray value, although the correction is model-dependent and intrinsically weaker X-ray variability may also contribute. However, X-ray spectra show no compelling evidence for intrinsic gas absorption or its variability ($N_{\rm H}^{\rm intr}\lesssim5\times10^{20}$ cm$^{-2}$). In contrast, EP/WXT monitoring during the recent high state reveals order-of-magnitude X-ray fluctuations on monthly-to-sub-year timescales, exceeding contemporaneous optical variations. Meanwhile, the radio flux density remains stable at $\sim2$ mJy across all ASKAP observations since mid-2020. Together with optical/UV and MIR variability and the broad He II transition, these results favor intrinsic accretion-state changes as the primary driver, while allowing a secondary contribution from variable obscuration. The source displays a loop-like MIR color--magnitude evolution, likely driven by the delayed response of an extended torus. This recurrent CLAGN offers a laboratory for probing the dynamic response of the broad-line region and circumnuclear dust to accretion-state transitions.
[abstract 22 / 53] (score: 3) - Title: Extended 2.25/8.60 GHz Observations of the Magnetar SWIFT J1818.0-1607Authors: Zhi-Peng Huang, Zhen Yan, Zhi-Qiang Shen, Hao Tong, Wei-Yang Wang, Xiao-Yu Lai, Rong-Bing Zhao, Ya-Jun Wu, Rui Wang, Xiao-Wei Wang, Fan Yang, Chu-Yuan Zhang, Zhen-Long Liao, Yang-Yang Lin,Comments: 15 pages, 6 figures, accepted by MNRASSubjects: astro-ph.HECreated: 2026-11-03; Updated: 2026-11-04; Datestamp: 2026-11-04
We present the long-term rotational evolution and radio emission properties of the MAGNETar SWIFT~J1818.0$-$1607, using simultaneous 2.25/8.60~GHz observations obtained with the Shanghai Tian Ma Radio Telescope from MJD~58936 to 59427. The average pulse profiles exhibit significant evolution with time and frequency, attributable to relative changes in the leading, central, and trailing emission components. The MAGNETar generally spins down with an average rate of $-1.65(4)\times10^{-11}\,\mathrm{s^{-2}}$, with the magnitude of the spin-down rate first increasing and then decreasing over the monitoring span. The overall flux density shows an initial rise followed by a decline, with sporadic variability superimposed; the variations at 2.25 and 8.60~GHz are broadly consistent across most epochs. The two-point spectral index increased from $α\simeq-1.8$ shortly after the outburst to near-zero values around MJD~59030--59050, followed by repeated decreases and increases. Despite this variability, 41 of the 54 two-point spectral-index measurements in the later campaign have $α>-1$. Three component-dependent types of mode changing are identified: Type~I, involving primarily intensity changes in the central component; Type~II, involving central and trailing components; and Type~III, involving leading and central components. All three classes include events showing a corresponding component response in the other observing band, with event-dependent response strengths and directions. Type~I variations are generally more pronounced at 8.60~GHz than at 2.25~GHz.
[abstract 23 / 53] (score: 3) - Title: Black Hole Mass Estimation of a Background Quasar in the Vicinity of the cD Galaxy Holm 15AAuthors: Emmanuel Ríos-López, Omar López-Cruz, Ana Luisa González-Morán, Christopher Añorve,Comments:Subjects: astro-ph.GACreated: 2026-11-03; Updated: 2026-11-04; Datestamp: 2026-11-04
This study analyzes spectra from the central region of the galaxy cluster Abell 85 observed with GTC/OSIRIS, focusing on the cD galaxy Holm 15A and the point-like X-ray source SDSS J004150.75-091824.3, projected $13.74\arcsec$ from Holm 15A. For the latter, we found it is a background QUASAR with a redshift of $1.56386 \pm 0.00397$, ruling out the possibility of it being a rogue BH gravitationally bound to Holm 15A. In addition, using single-epoch spectroscopy, we report that the QUASAR J004150 hosts a Supermassive Black Hole (SMBH) with a mass of $\log(M_{\text{BH}}/\mathrm{M_{\odot}}) = 8.72 \pm 0.26$.
[abstract 24 / 53] (score: 3) - Title: SN 2019qem: decades of extreme mass loss before the explosion of a luminous, long-lived Type IIn SUPERNOVAAuthors: Joysankar Majumdar, Mariusz Gromadzki, Takashi J. Moriya, David A. H. Buckley, Priscila J. Pessi, Nada Ihanec, Szymon Kozłowski, Łukasz Wyrzykowski, Callum Aster, Panos Charalampopoulos, Ting-Wan Chen, Massimo Della Valle, Lluís Galbany, Avishay Gal-Yam, Claudia P. Gutiérrez, Cosimo Inserra, Erkki Kankare, Hanindyo Kuncarayakti, Tomás E. Müller-Bravo, Matt Nicholl, Jacco H. Terwel, David R. Young, Andrzej Udalski, Michał K. Szymański, Igor Soszyński, Paweł Pietrukowicz, Radosław Poleski, Jan Skowron, Krzysztof Ulaczyk, Przemek Mróz, Krzysztof Rybicki, Patryk Iwanek, Marcin Wrona, Mateusz J. Mróz, Moira Andrews, Craig Pellegrino, D. Andrew Howell, Curtis McCully, Daichi Hiramatsu, Megan Newsome, Giacomo Terreran, Estefania Padilla Gonzalez, Joseph R. Farah, Mauritz Wicker, Michał Małkowski, Andrew Fraser Gillan,Comments: Submitted to A&A with 20 pages, 15 figuresSubjects: astro-ph.HE astro-ph.SRCreated: 2026-11-03; Updated: 2026-11-04; Datestamp: 2026-11-04
We present the luminous, long-lived Type IIn SN 2019qem and use it to reconstruct how much mass its progenitor lost and when. We combine host-subtracted optical and mid-infrared photometry and 26 optical spectra from -22 to +699 d. We model the bolometric light curve with thin-shell CSM-interaction models in REDBACK, with the shock velocity constrained by the H$α$ line widths, and compare them with an analytic interaction model. SN 2019qem rose in $\approx30$d to $M_I = -20.5$mag and a bolometric peak of $7.0\times10^{43}$ erg s$^{-1}$, and radiated $6.9\times10^{50}$ erg in the optical within 575 d, closely resembling luminous, strongly interacting SNe IIn such as SN 2010jl and SN 2015da. A Heii/Niii flash feature at -22 d and unresolved narrow Balmer lines reveal dense, slow CSM. From +78 to +445 d the H$α$ wings are shaped by electron scattering, and the line stays blueshifted by 400-700 km s$^{-1}$, which points to an optically thick, asymmetric interaction region rather than to newly formed dust. In the preferred model, $\approx7 M_\odot$ of ejecta run into $\approx9 M_\odot$ of gas ejected $\approx2$ yr before explosion and then into a wind of $\approx0.6 M_\odot$ yr$^{-1}$ (for $v_w = 100$ km s$^{-1}$), sweeping up $\approx32 M_\odot$ by +544 d. The mid-infrared excess brightens for two years while the optical fades, tracing dust heated by the ongoing interaction. The host is a low-mass, star-forming galaxy, $\log(M_*/M_\odot) = 9.19$, with a sub-solar metallicity at the explosion site. In its final decades the progenitor of SN 2019qem lost mass far faster than any steady stellar wind, ending with an eruption of $\approx9 M_\odot$ two years before core collapse, consistent with luminous-blue-variable-like eruptive mass loss. Taken at face value, the mass budget implies an initial progenitor mass of $\gtrsim40 M_\odot$.
[abstract 25 / 53] (score: 2) - Title: Einstein-non-linear Maxwell-Yukawa BLACK HOLEAuthors: S. Habib Mazharimousavi, M. Halilsoy,Comments: Final copy 9 pages and 6 figuresSubjects: gr-qcCreated: 2026-11-03; Updated: 2026-11-04; Datestamp: 2026-11-04
Within the context of nonlinear electroMAGNETism, we consider the Yukawa extension of a Reissner-Nordström BLACK HOLE. An exact solution is given which modifies certain characteristics of the latter. Some thermodynamical aspects are given for comparison. The model provides a gauge-invariant nonlinear-electrodynamic realization of a screened electric potential; the Yukawa form by itself does not establish a massive vector excitation. The exact spacetime solution and its thermodynamic properties are examined with the exponential-integral contribution.
[abstract 26 / 53] (score: 2) - Title: On the stability and emittance growth of different particle phase-space distributions in a long MAGNETic quadrupole channelAuthors: Jürgen Struckmeier, Jürgen Klabunde, Martin Reiser,Comments: 22 pages, 10 figuresSubjects: physics.plasm-ph physics.acc-phCreated: 2026-11-03; Updated: 2026-11-04; Datestamp: 2026-11-04
The behavior of K-V, waterbag, parabolic, conical and Gaussian distributions in periodic quadrupole channels is studied by particle simulations. In the parameter range studied, the response associated with the K-V instabilities becomes progressively less pronounced toward the Gaussian distribution. For the third-order instability studied here, the emittance growth factor of an initially Gaussian beam after a large number of periods is considerably lower than that of an equivalent K-V distribution.\newline\indent In addition, the non-K-V distributions exhibit a rapid initial emittance growth within approximately one period of the channel, which becomes very significant at high beam intensities. This growth is attributed to the homogenization of the space-charge density, resulting in a conversion of electric-field energy into transverse kinetic and potential energy. Two simple analytical formulae based on different energy-partition assumptions are derived as estimates for this effect and are compared with the results obtained from particle simulations. They are not rigorous lower and upper bounds for arbitrary beam evolution. \\[6pt] Revised version of: Particle Accelerators {\bf 15}, 47--65 (1984)}
[abstract 27 / 53] (score: 2) - Title: Direct evidence of non-ideal MHD in the solar wind and switchbacksAuthors: Forrest Mozer, Oleksiy Agapitov, Kyung-Eun Choi, Richard Sydora,Comments: 12 pages, 6 figuresSubjects: astro-ph.SRCreated: 2026-11-02; Updated: 2026-11-04; Datestamp: 2026-11-04
The low frequency solar wind and its switchbacks are sometimes characterized as ideal-MHD plasmas containing Alfvenic turbulence and, sometimes, as non-ideal plasmas whose turbulence cannot be Alfvenic. The reason for this ambiguity is that definitive measurements of electric fields in the plasma rest frame at fluid frequencies have not been made and such measurements rule out the possibility of one or the other of the two modes. The FIELDS electric field measurement on the Parker Solar Probe is capable of such measurements which are reported in this paper. At radial distances less than 40 solar radii on orbit 10, perpendicular and parallel electric fields in the plasma rest frame at frequencies of 0.01 to 0.1 Hz and over a broad frequency range are observed. The parallel electric fields survive in the presence of calibration errors because their amplitude, but not their existence, is affected by them. Errors in the perpendicular electric field or the solar wind velocity can produce large errors in the plasma rest frame perpendicular electric field because it is the difference of two large quantities, the electric field and the negative velocity-cross-MAGNETic-field. Evidence is presented that this does not happen, at least much of the time. Because both perpendicular and parallel electric fields in the plasma rest frame are observed at low frequencies, the solar wind and its switchbacks reside in a non ideal MAGNETohydrodynamic environment. Consequently, standard ideal MHD treatments, including ideal Alfven, slow, and fast wave formulations, cannot adequately describe the turbulent solar wind dynamics. Similar considerations may apply in other astrophysical plasmas.
[abstract 28 / 53] (score: 2) - Title: Perturbative dynamics and RELATIVISTIC effects of a dyonic Kalb-Ramond BLACK HOLEAuthors: A. A. Araújo Filho,Comments: 74 pages and 28 figures -- version accepted for publication in Annals of PhysicsSubjects: gr-qc hep-thCreated: 2026-11-03; Updated: 2026-11-04; Datestamp: 2026-11-04
We investigate perturbative dynamics, tidal effects, and RELATIVISTIC frequency shifts in a dyonic Kalb-Ramond BLACK HOLE generated by a Lorentz-violating antisymmetric tensor background. The geometry is controlled by the mass $M$, the electric charge $Q$, the MAGNETic charge $p$, and the Lorentz-violating parameter $\ell$, with the dyonic sector entering through the effective combination $P_{\ell}^{2}=Q^{2}/(1-\ell)^{2}+p^{2}/(1-2\ell)$. First, we analyze the gravitational Doppler effect for radial signal exchange between freely falling and static observers, showing how the dyonic charges weaken the redshift by shifting the frequency ratio toward unity. We then compute the radial and angular tidal forces in a freely falling frame and determine the characteristic radii at which the usual stretching and compression patterns are reversed. The gravitational time delay is also evaluated for null trajectories, showing that the electric and MAGNETic sectors reduce the delay relative to the reference configuration. In the perturbative sector, we study massless scalar, vector, and spinor test fields together with an effective axial metric model, computing sixth-order WKB spectra and independently checking selected modes using the asymptotic iteration method. At fixed mass and charges, increasing the Lorentz-violating parameter raises the tabulated oscillation frequencies and damping rates in the original time coordinate; their interpretation accounts for time normalization and changes in effective parameters. The independent comparisons support the tested higher-multipole fundamental modes. Time-domain evolutions exhibit damped ringdown followed by power-law tails, whose exponents are estimated through fits incorporating finite time corrections and numerical sensitivity checks.
[abstract 29 / 53] (score: 2) - Title: Memoirs of the curvaton: non-perturbative non-Gaussianity and supermassive primordial BLACK HOLEsAuthors: S. Allegrini, A. J. Iovino, G. Perna, H. Veermäe,Comments: 39 pages + Appendix, 12 figures. Matches the version published in JCAPSubjects: astro-ph.CO astro-ph.HE gr-qcCreated: 2026-11-03; Updated: 2026-11-04; Datestamp: 2026-11-04
The curvaton provides a simple mechanism for generating strongly non-Gaussian curvature perturbations after inflation, with potentially important consequences on small scales. We study curvaton dynamics beyond the standard quadratic potential and construct the local non-Gaussian map $ζ=F(ζ_{\rm G})$ relating the curvature perturbation to an auxiliary Gaussian field $ζ_{\rm G}$. Curvaton self-interactions make the onset of oscillations field dependent and modify the effective equation of state once the curvaton enters the adiabatic regime. We incorporate these effects using the abbreviated action, which provides a compact way to connect the frozen and oscillatory regimes and exposes sources of non-Gaussianity absent in the purely quadratic case. We apply the formalism to quadratic, monomial, quartic, and cosine potentials, for which we derive the mapping $F(ζ_{\rm G})$ and show that self-interactions can either enhance or suppress the resulting non-Gaussianity depending on the potential and initial conditions. We consider non-perturbative aspects in the strongly non-Gaussian regime, and show how strong non-Gaussianity can suppress the power spectrum. As an application, we provide a bottom-up scenario in which strongly positive curvaton non-Gaussianity allows primordial supermassive BLACK HOLE seeds at peak amplitudes $\mathcal{A}_\textrm{pk}\sim10^{-3}$, which are compatible with the COBE/FIRAS $μ$-distortion bounds. This opens a new primordial scenario for the Little Red Dots observed by the JWST. The axion-like curvaton provides a particularly natural setting for this mechanism.
[abstract 30 / 53] (score: 2) - Title: Landau-Zener formula and resonant axion conversion in neutron star MAGNETospheresAuthors: Matti Heikinheimo, Topi Sirkiä, Kimmo Tuominen,Comments: 12 pages, 6 figures. v2. Accepted for publication in Physics review DSubjects: hep-ph astro-ph.HECreated: 2026-11-03; Updated: 2026-11-04; Datestamp: 2026-11-04
We investigate the Landau-Zener description of resonant axion-photon conversion in neutron star MAGNETospheres. We find that this picture often fails for axion conversions to millimeter-to-optical band photons due to the characteristic resonance width exceeding the size of the conversion region. This comparison of scales yields a simple criterion for evaluating the validity of the Landau-Zener formula. We verify this criterion numerically, and show that when invalid, the Landau-Zener conversion probability may significantly deviate from the numerical result. In light of these findings, we revise constraints on axions from neutron star optical-band POLARIZATION searches.
[abstract 31 / 53] (score: 2) - Title: Eccentricity as a Magnifying Glass: Precision Population Inference Enabled by Eccentric Neutron Star-Black Hole MergersAuthors: Alberto Salvarese, Hsin-Yu Chen, Aaron Zimmerman, Snehal Tibrewal,Comments: Accepted version by The Astrophysical Journal. 12 pages, 6 figures, 3 tablesSubjects: astro-ph.HECreated: 2026-11-03; Updated: 2026-11-04; Datestamp: 2026-11-04
The formation history of compact binary systems remains one of the key open questions in astrophysics. Theoretical studies generally favor isolated binary evolution for neutron star-BLACK HOLE (NSBH) systems, which tends to produce nearly circular orbits. However, recent analyses of the gravitational-wave event GW200105 indicate that its source has measurable eccentricity, suggesting that alternative formation channels may also contribute. It has been shown that the intrinsic parameters of eccentric NSBH mergers, such as the component masses and spins, are much better measured than circular mergers with LIGO-Virgo-KAGRA (LVK) observatories. We explore how such eccentricity-enhanced parameter measurements can affect the inference of NSBH formation channels. We find that sharper measurements of the effective spin parameter $χ_{\rm eff}$ increase the fraction of systems for which negative values can be confidently identified, allowing for the clear measurement of a spin-orbit misaligned event every $\sim 2.5$ eccentric NSBH detections for an isotropically distributed population in the fifth LVK observing run (O5). Improved neutron star (NS) mass measurements provide better constraining power for NS mass distributions, potentially revealing structure and tightening the bounds that can be drawn on their upper and lower masses. Similarly, the recovery of a metallicity-dependent BH mass distribution is improved by eccentricity-enhanced measurements. Finally, we show that the proposed population-level eccentricity distribution for dynamical-formation channels can be tested by the end of O5.
[abstract 32 / 53] (score: 2) - Title: Multipolar neutrino radiation in binary neutron star mergers: Angular structure, rotational variability, and implications for electron fractionAuthors: Kutay Arınç Çokluk, Albino Perego, Federico Maria Guercilena, Kadri Yakut,Comments: 28 pages, 13 figures, 2 tables. Accepted for publication in Physical Review DSubjects: astro-ph.HE gr-qc hep-phCreated: 2026-11-03; Updated: 2026-11-04; Datestamp: 2026-11-04
The angular structure and temporal variability of neutrino emission from binary neutron star mergers are characterized using fully general-RELATIVISTIC simulations with energy-integrated M1 neutrino transport across a representative set of equations of state, total masses and mass ratios. The main analysis is restricted to merger remnants that do not collapse to a BLACK HOLE within the simulated time intervals. The angle-dependent neutrino energy flux is extracted on a spherical surface outside the remnant and decomposed into spherical harmonics to quantify its multipolar content and evolution. Following the initial post-merger transient, the neutrino radiation flux approaches an axisymmetric configuration dominated by a strong quadrupolar component, producing persistent polar flux enhancement and equatorial suppression due to torus shadowing. The dipolar contribution remains subdominant, indicating the absence of sustained one-sided emission. The degree of anisotropy increases with mass asymmetry and for softer equations of state, reflecting the compactness and morphology of the remnant--disk system. Superimposed on this time-averaged geometry, coherent azimuthal modulations associated with the $m=1$ mode are identified. The associated half frequency, $f_{\mathrm{dom}}/2\simeq0.6$--$0.7\,\mathrm{kHz}$, is compared with local rotation rates in the simulated remnant--disk systems, suggesting a possible dynamical association between the remnant structure and neutrino variability. Finally, we quantify how the same quadrupole-dominated radiation geometry induces a latitude-dependent equilibrium electron fraction. The polar material is driven close to the neutrino-equilibrium target, whereas equatorial material remains systematically more neutron rich and below equilibrium.
[abstract 33 / 53] (score: 2) - Title: Stabilization of counter propagating currents by energy conservation in collisionsAuthors: Thomas Kluge, Jannis Schulz, Arthur Hirsch-Passicos, Pawel Ordyna, Ulrich Schramm,Comments:Subjects: physics.plasm-phCreated: 2026-11-02; Updated: 2026-11-04; Datestamp: 2026-11-04
Current filamentation generates MAGNETic fields and shapes electron transport in dense plasmas, where collisions can either suppress or enhance its growth. Here we show that conserving electron kinetic energy in a collisional model can change both the dominant instability and its characteristic wavelength. We develop a linear kinetic theory for drifting, anisotropic electron populations with a relaxation operator that conserves particle number and laboratory-frame kinetic energy while allowing momentum transfer to a stationary ion background. For counterstreaming currents, energy conservation maintains the stabilizing influence of charge separation over a broader range of collision frequencies than a model conserving particle number alone. At intermediate collision rates, the resulting suppression of transverse filamentation allows a nearly aperiodic oblique mode to dominate, reducing the maximum growth rate and shifting the wavelength of the fastest-growing perturbation. Two-dimensional particle-in-cell simulations support predicted growth rates of up to more than a magnitude lower than expected without energy conserving collision.
[abstract 34 / 53] (score: 2) - Title: Stabilization of kinetic plasma instabilities via instantaneous external field controlAuthors: Jiyoung Yoo, Jingwei Hu,Comments: 23 pages, 8 figures, 1 tableSubjects: physics.plasm-phCreated: 2026-11-01; Updated: 2026-11-04; Datestamp: 2026-11-04
We propose an instantaneous control framework for the stabilization of kinetic plasma instabilities using external fields. The control problem is formulated as a PDE-constrained optimization that accounts for nonlinear plasma dynamics, while the control is determined at each time step to avoid global-in-time optimization. The Discretize-then-Optimize (DtO) approach is adopted, with the forward equations first discretized using a particle-in-cell (PIC) method. The subsequent control computation is derived from the discrete particle update, ensuring consistency with the forward solver. The control objective is formulated in terms of electroMAGNETic field energy and low-order moments rather than the full distribution function, making the optimization more amenable to practical implementation. The framework is applied to both electrostatic and electroMAGNETic settings and evaluated on several benchmark problems, including the two-stream, bump-on-tail, Dory--Guest--Harris, and Weibel instabilities. Across these tests, the control successfully suppresses field energy growth and keeps the distribution function close to its initial state. These results demonstrate the effectiveness of the proposed strategy in suppressing kinetic plasma instabilities.
[abstract 35 / 53] (score: 2) - Title: Ly$α$ in Compact Broad-Line Emitters, Including Little Red Dots, Is More Closely Linked to the Host Galaxy than to the Broad-Line NucleusAuthors: Yongda Zhu, Zheng Ma, Xiaojing Lin, Junyu Zhang, Jianwei Lyu, Xiaohui Fan, Eiichi Egami, Andrew J. Bunker, Sijia Cai, Laura C. Keating, Joseph Shields, Zhiyuan Ji, Xiangyu Jin, Weizhe Liu, Suprabhas Narisetty, George H. Rieke, Marcia J. Rieke, Pierluigi Rinaldi, Fengwu Sun,Comments: 12 pages, 5 figures, 1 table. Submitted to AAS journalsSubjects: astro-ph.GA astro-ph.COCreated: 2026-11-02; Updated: 2026-11-04; Datestamp: 2026-11-04
JWST has found many faint broad-line AGN at $z>4$, but it is unclear whether the Ly$α$ we see from them comes from the accreting BLACK HOLE or from its host galaxy. The answer matters for how these sources are interpreted and for how many ionizing photons they release. We use deep JWST/NIRSpec spectroscopy from the DIVER program to measure Ly$α$ in 12 compact broad-line emitters (CBEs) at $z=4.2$--5.5 in GOODS-N. CBEs include little red dots (LRDs), little blue dots, and other broad-line AGN. Six are detected in Ly$α$. Every source shows a broad-line region, yet Ly$α$ does not follow it: the sources with the strongest H$α$ relative to the UV include weak detections and nondetections, and every detected Ly$α$ line (FWHM $\approx300$--1000~km~s$^{-1}$) is narrower than broad H$α$ (1100--3300~km~s$^{-1}$). Instead, Ly$α$ appears to track the host galaxy. We model the AGN-subtracted host with a dust-attenuated SED fit. Including the upper limits, the observed Ly$α$ follows the Ly$α$ production in this host model more closely than it follows H$α$/UV, in both equivalent width and luminosity. Every detection exceeds its host-model value by a factor of 1.5--18, leaving room for a nuclear contribution. The BLACK HOLE is visible in these sources, but the Ly$α$ we observe is more closely tied to its host. The median effective Ly$α$ escape fraction of the detections is only 0.09, which suggests that ionizing escape from CBEs is typically modest and varies widely.
[abstract 36 / 53] (score: 2) - Title: The STARfall pathway: forging intermediate-mass BLACK HOLEs through stellar collisions in dense star clustersAuthors: Filippo Simonato, Manuel Arca Sedda, Taeho Ryu, Jakub Klencki, Giuliano Iorio, Sara Rastello, Lavinia Paiella, Cristiano Ugolini, Benedetta Mestichelli, Marica Branchesi, Abbas Askar, Peter Berczik, Guglielmo Costa, Mirek Giersz, Albrecht W. H. Kamlah, Rainer Spurzem, Stefano Torniamenti, Marcelo C. Vergara,Comments: 22 pages, 15 figures, 3 tablesSubjects: astro-ph.GACreated: 2026-11-02; Updated: 2026-11-04; Datestamp: 2026-11-04
Intermediate-mass BLACK HOLEs (IMBHs, $10^2 < m_{\rm BH}/\mathrm{M}_{\odot} < 10^5$) are elusive objects bridging the gap between stellar-mass and supermassive BLACK HOLEs, whose origin remains uncertain. They may form from the collapse of very massive stars (VMSs, $m_*\geq150\,\mathrm{M}_{\odot}$) assembled through repeated stellar collisions in compact and fast evolving star clusters. We investigate the formation of VMSs and IMBH seeds via repeated mergers and collisions as a function of cluster initial conditions, assessing the implications for globular clusters and dense high-redshift system. We develop STARfall, a semi-analytic tool that follows the evolution of a massive stellar binary via binary-single interactions, mergers, collisions, and stellar evolution, while consistently accounting for the host cluster evolution. Our results show that clusters with central densities above $10^6\,\mathrm{M}_{\odot}\,\mathrm{pc}^{-3}$ can undergo a catastrophic sequence of stellar collisions, or "starastrophe", within $3$ Myr. Through this process, VMSs rapidly grow in mass and collapse into IMBHs with masses of up to $10^3-10^4\,\mathrm{M}_{\odot}$, despite the effects of intense stellar winds. Applying our models to observed systems, we find that compact clusters in the Cosmic Gems Arc and Milky Way globular clusters could have hosted VMSs that collapsed into IMBHs in this mass range. Despite their longer core-collapse timescales, the inferred central densities of Little Red Dots may also support IMBH formation in the same mass interval. Our models show that VMS assembly requires two essential ingredients: short core-collapse times and large central densities. Compared to observed systems, our models suggest that clusters in the Cosmic Gems Arcs and several Galactic globular clusters could have nurtured VMSs that directly collapsed to IMBHs with masses $10^3-10^4\,\text{M}_{\odot}$.
[abstract 37 / 53] (score: 2) - Title: Towards Self-consistent Modeling of Quasi-Stars and their NLTE Spectra: Implications for Little Red DotsAuthors: Jake B. Hassan, Rosalba Perna, Mitchell C. Begelman, Yan-Fei Jiang, Matteo Cantiello, Philip J. Armitage, Taeho Ryu,Comments: 18 pages, 12 figuresSubjects: astro-ph.SR astro-ph.COCreated: 2026-11-02; Updated: 2026-11-04; Datestamp: 2026-11-04
Quasi-stars, massive envelopes surrounding rapidly accreting BLACK HOLE (BH) seeds, are promising candidates for explaining the rapid formation of supermassive BLACK HOLEs in the early Universe and may account for some of the JWST-discovered Little Red Dots (LRDs). We present a self-consistent framework combining stellar evolution calculations with non-local thermodynamic equilibrium (NLTE) spectral synthesis to test this connection. Our models drop the polytropic assumptions of previous work: the envelope is described entirely by mixing-length theory, with saturated convection and radiative energy setting the luminosity at an inner boundary a few hundred Schwarzschild radii from the BH. This removes the BH-mass limits of earlier models, and we follow the evolution up to BH-to-total mass ratios approaching unity. We then use TLUSTY to compute the first converged NLTE atmospheric models for the surface conditions and primordial hydrogen-helium composition expected in quasi-stars. Our models produce cool photospheres, prominent Balmer breaks, and Balmer and Paschen absorption features. NLTE effects substantially modify line strengths, increasing Balmer absorption depths by $\sim 35-55\%$ relative to LTE models, while having a minor effect on the continuum. Comparison with observed LRD spectral energy distributions shows broad agreement in continuum shape, although our models do not reproduce their commonly observed strong emission lines. Under the quasi-star interpretation, comparisons with individual LRDs suggest characteristic quasi-star masses of approximately $10^5-10^7 M_\odot$. These results establish a physically motivated connection between quasi-star evolution and observable spectra, providing a framework for testing quasi-stars as progenitors of LRDs while identifying limitations of current atmospheric models.
[abstract 38 / 53] (score: 2) - Title: X-rays from Low-mass Active Galaxies in the Galaxy And Mass Assembly (GAMA) SurveyAuthors: Stellan Bechtold, Amy Reines, Richard Plotkin, Sheyda Salehirad,Comments: 19 pages, 8 figures, 7 tables. Submitted to ApJSubjects: astro-ph.GACreated: 2026-11-02; Updated: 2026-11-04; Datestamp: 2026-11-04
We present new Chandra observations of seven broad-line AGNs in low-mass galaxies ($M_\star < 5 \times 10^9\,M_\odot$) selected from the GAMA sample of Salehirad et al. (2022). X-ray emission is detected in six galaxies, with luminosities spanning $\log(L_{\rm 0.5-8\,keV}/{\rm erg\,s^{-1}})\approx40.5$--43.8. Their X-ray luminosities generally exceed predictions for X-ray binary populations, and their proximity to the optical galaxy nuclei favors accreting massive BLACK HOLEs as the dominant emission source. Spectral fits for four sources yield photon indices $Γ\approx1.7$--2.2, with little evidence for intrinsic absorption in most cases. Virial BLACK HOLE masses and hard X-ray bolometric corrections imply nominal Eddington ratios $λ_{\rm Edd}\approx0.004$--1.1, although uncertainties are substantial. Optical tracers generally imply higher bolometric luminosities and Eddington ratios, particularly for the X-ray-undetected galaxy. The X-ray-bright sources are broadly consistent with optical AGN scaling relations involving H$α$ and [O III], whereas most lie below the established X-ray--mid-infrared relation, potentially reflecting host-galaxy contamination. Four sources are consistent with the expected UV-to-X-ray spectral slope relation, while three show evidence for relative X-ray weakness. These results reveal diverse X-ray properties among broad-line AGNs in low-mass galaxies and highlight the importance of multiwavelength diagnostics for understanding BLACK HOLE accretion and interpreting broad-line AGN candidates at high redshift.
[abstract 39 / 53] (score: 2) - Title: Obstruction to local entropy laws on arbitrary black-hole cuts in five-dimensional Einstein--Gauss--Bonnet gravityAuthors: Cendikiawan Suryaatmadja, Robert B. Mann,Comments:Subjects: hep-thCreated: 2026-11-02; Updated: 2026-11-04; Datestamp: 2026-11-04
We study local entropy laws on arbitrary cuts of event horizons in five-dimensional Einstein--Gauss--Bonnet gravity, treated as an exact theory. No covariant local entropy can both reproduce the stationary black-hole entropy and be nondecreasing between every ordered pair of cuts, provided its density is smooth on an invariant open set of off-shell metric and cut JETs containing a flat planar cut and every cut used in the argument. No global bound on derivative order is assumed. The counterexamples to the second law are vacuum BLACK HOLEs perturbed by a gravitational wave, with a strongly hyperbolic formulation near the relevant horizon interval and its stationary future. Shear makes the intrinsic curvature of a cut depend on its bending. The stationary entropy fixes the coefficient of this curvature term, and local corrections cannot cancel its response to cut bending. The obstruction appears at second order in wave amplitude on a smooth horizon, without a merger or topology change.
[abstract 40 / 53] (score: 2) - Title: Holographic spin alignment of vector mesons in a spinning black-hole backgroundAuthors: Fei Wang, Zi-qiang Zhang,Comments: 19 pages, 8 figuresSubjects: hep-phCreated: 2026-11-03; Updated: 2026-11-04; Datestamp: 2026-11-04
Holographic predictions for vector-meson spin alignment are difficult to compare between charmonium and light vector mesons, as the two sectors are typically treated in different rotating backgrounds and spectral prescriptions. Consequently, it remains unclear whether a single rotating medium can generate the opposite POLARIZATION preferences observed in data. We address this by placing \(J/ψ\) and \(ϕ\) in one soft-wall model on the planar limit of a five-dimensional equal-spin Myers--Perry (MP) AdS BLACK HOLE, computing spectral functions and spin alignment within the same current-correlator framework; the nonrotating results of Sheng et al. [Phys. Rev. D 110, 056047 (2024)] are recovered at \(a=0\). At \(T=0.15~\mathrm{GeV}\), \(J/ψ\) retains a clear resonance peak, whereas \(ϕ\) shows no narrow peak and instead behaves as a broad distribution consistent with unstable \(s\bar{s}\) pairs. For \(J/ψ\) along \(z\), rotation enhances the positive deviation of \(ρ_{00}^{h}\) from \(1/3\) at low and intermediate momenta but suppresses it at high momenta; along \(x\), the effect is small. For \(ϕ\), rotation enhances the negative deviation, more along \(z\) than along \(x\). The opposite helicity-frame signs and the opposing azimuthal and rapidity trends of the global alignment provide a reference for interpreting data: trends inconsistent with these would challenge the simplest single homogeneous rotating-medium interpretation. We distinguish model-dependent numerical details from qualitative features stable within this model class.
[abstract 41 / 53] (score: 2) - Title: Photon arrival time lags in 3D radiative transfer with SKIRTAuthors: Yuto Mochizuki, Bert Vander Meulen, Masahiro Tsujimoto, Peter Camps, Maarten Baes, Arno Lauwers, Gijs Vanoppen,Comments:Subjects: astro-ph.HE astro-ph.IMCreated: 2026-11-03; Updated: 2026-11-04; Datestamp: 2026-11-04
Reprocessed X-ray emission from cold material surrounding compact objects carries critical information about the geometry and physical state of the system. In particular, the Fe K$α$ fluorescence line provides a powerful diagnostic through its spectral and timing properties relative to the direct emission. Interpreting these observables requires self-consistent modelling of radiative transfer (RT) in three-dimensional (3D) space. We aim to implement photon arrival time lags in SKIRT, a Monte Carlo RT code, thereby enabling self-consistent modelling of both the spectral and timing properties of reprocessed emission in 3D space. We modified the code to accumulate photon path lengths over their lifetimes and convert them into arrival time lags relative to the direct emission. The implementation is validated using simple geometries and then applied to a realistic model of an ACTIVE GALACTIC NUCLEus (AGN), for which we compute the time-lag and energy distribution and the cross-correlation functions (CCFs) between the fluorescence line and broad bands. The simulations reproduce the expected time-lag distributions and their energy dependence for both free-electron scattering and the photoelectric absorption $+$ fluorescence. In the AGN application, the model naturally yields distinct lag components from the inner and outer structures, as well as energy-dependent time lags associated with the fluorescence line. The derived CCFs successfully recover both the peak time lag and its finite width, which arise from the extended geometry and intrinsic variability. In X-rays, this capability provides a robust framework for interpreting high-resolution spectroscopic data in conjunction with timing information from current and future missions such as XRISM and NewAthena. A wide range of applications is foreseen, including reverberation mapping studies of accreting systems.
[abstract 42 / 53] (score: 2) - Title: Measuring the ultraviolet background at $z\simeq3$ from the QUASAR proximity effect in DESI DR1Authors: Patrick Shaw, Rupert A. C. Croft,Comments:Subjects: astro-ph.COCreated: 2026-11-03; Updated: 2026-11-04; Datestamp: 2026-11-04
Ionizing radiation from QUASARs reduces the abundance of neutral hydrogen in the surrounding intergalactic medium (IGM), suppressing Ly$α$ absorption. This absorption deficit, known as the QUASAR proximity effect, can be used to measure the ultraviolet background (UVBG). We measure the hydrogen photoionization rate of the UVBG in Data Release 1 of the Dark Energy Spectroscopic Instrument (DESI). Our sample contains 6,245 QUASARs over $2.75\leq z<3.25$, selected with rest-frame absolute magnitudes at 1450 Angstroms of $M_{1450}\leq-25.5$ and signal-to-noise ratios of at least 3 measured redward of Ly$α$. We reconstruct QUASAR continua with principal component analysis trained on Hubble Space Telescope spectra and stack the resulting transmitted-flux profiles. We fit the resulting stacked profile with a halo model that accounts for reduced absorption from QUASAR radiation and enhanced absorption in the surrounding overdense environment. We constrain the environmental contribution using independent measurements of QUASAR clustering bias, while the transmission profile constrains the UVBG. To validate our method, we construct mock spectra matched to the luminosity and noise properties of our DESI sample using the Astrid hydrodynamical simulation at $z=3$. We apply the same analysis pipeline to the mock spectra and DESI data, testing the recovery of known input photoionization rates and using the results to calibrate the final UVBG measurement. We obtain $Γ_{\mathrm{HI}}=(1.376^{+0.095}_{-0.076})\times10^{-12}\,\mathrm{s}^{-1}$ at $z\simeq3$. The statistical errors are obtained by bootstrap resampling the DESI sightlines. We also estimate a systematic uncertainty of $^{+0.837}_{-0.521}\times10^{-12}\,\mathrm{s}^{-1}$.
[abstract 43 / 53] (score: 2) - Title: Conceptual Design of Pumping Systems up to 1000 m3/s Based on Non-Evaporable Getters in a Gas-Dynamic Magnetic TrapAuthors: Alexey M. Semenov, Nataliy G. Vasilieva, Sergey V. Polosatkin,Comments:Subjects: physics.plasm-phCreated: 2026-11-03; Updated: 2026-11-04; Datestamp: 2026-11-04
The Gas-Dynamic Magnetic Trap (GDMT), a new linear MAGNETic facility for confining high-temperature hydrogen plasma, is currently under development at the Budker Institute of Nuclear Physics (BINP SB RAS). The total hydrogen flow that must be removed from the end expanders by the vacuum system is approximately 10^22 molecules/s, which corresponds to a required pumping speed on the order of 500 m3/s. Non-evaporable getters (NEG) are considered as a possible pumping method for this application. This article presents experimental studies of Ti-Zr-Al getters manufactured by Polema LLC. The pumping speed, sorption capacity, and sticking factors of the getter surface were measured. The sticking factors for hydrogen and deuterium are 2.23% and 1.54%, respectively. The getter pumping speed is maintained over 60 air-vent/reactivation cycles. Based on these results, a conceptual design of a NEG-based pumping system for the GDMT end expanders is proposed, providing a specific pumping speed of 74 m3/(m3s) for the getter panel. The proposed pumping system design and the required heating power are discussed.
[abstract 44 / 53] (score: 2) - Title: The preplasma origin of the plasma-mirror reflectivity responseAuthors: Zhongwei Wang, Douglass Schumacher,Comments: 10 pages, 8 figuresSubjects: physics.plasm-phCreated: 2026-11-03; Updated: 2026-11-04; Datestamp: 2026-11-04
Plasma mirrors (PM) enhance the temporal contrast of high-power LASERs, but declining reflectivity at subRELATIVISTIC intensities limits their energy throughput. Here we show that prepulse-generated preplasma drives this decline in p POLARIZATION primarily through absorption. Particle-in-cell simulations using a measured prepulse profile reproduce the reflectivity decrease, with near- and far-field energy accounting showing a weak contribution from scattering. Optical-cycle-resolved electron tracking reveals successive electron bunches extracted from the plasma surface, supporting a vacuum-heating interpretation. Under the simulated conditions, s-polarized absorption remains weak and no comparable decline occurs. Applying the model to two representative double-plasma-mirror (DPM) systems, BELLA and CoReLS, it captures both the p-polarized and s-polarized reflectivity responses across the operating range. Yet, the model still misses the high-fluence s-polarized reflectivity rollover, and further investigation of the scattering channel might be needed. These findings connect prepulse history to POLARIZATION-dependent energy loss, informing the choice of plasma-mirror operating conditions.
[abstract 45 / 53] (score: 2) - Title: A Detailed Polarimetric Imaging Study of Type II Solar Radio Burst with the MWA: Detection of Linear PolarizationAuthors: Puja Majee, Devojyoti Kansabanik, Divya Oberoi,Comments: 13 pages, 6 figures, submitted to The Astrophysical Journal Letters, under reviewSubjects: astro-ph.SRCreated: 2026-11-03; Updated: 2026-11-04; Datestamp: 2026-11-04
Type II radio bursts, produced by MAGNETohydrodynamic shocks propagating through the solar corona and interplanetary medium, serve as powerful diagnostics of shock properties and ambient coronal MAGNETic fields. While circular POLARIZATION in type II bursts has been extensively studied, most investigations rely on dynamic spectra (DS), providing only spatially integrated measurements. DS obscures spatial variations of the POLARIZATION sign and magnitude, potentially causing cancellation effects and misrepresenting true POLARIZATION levels. We present a full-polarimetric imaging study of a metric type II burst observed with the Murchison Widefield Array at 78--133 MHz. Remarkably, we report the first detection of linear POLARIZATION in a metric type II burst, reaching a POLARIZATION fraction of $\sim12\%$ with significant spectro-temporal variability across observing bands. The spectro-temporal, spatial, and morphological properties found in this study establish linear POLARIZATION as a new diagnostic of large-scale coronal and interplanetary MAGNETic field structure through full-Stokes imaging of metric solar radio bursts -- challenging conventional paradigms predicting negligible linear POLARIZATION from coherent plasma emission processes.
[abstract 46 / 53] (score: 2) - Title: A New Precise Measurement of the $e^+e^-\toπ^+π^-(γ)$ Cross Section with the Initial-State Radiation Method at BaBarAuthors: BaBar Collaboration,Comments: 6 pages, 3 figures, and 1 tableSubjects: hep-exCreated: 2026-11-03; Updated: 2026-11-04; Datestamp: 2026-11-04
We measure the $e^+e^-\toπ^+π^-(γ)$ cross section from threshold to 1.4 GeV using 460 fb$^{-1}$ of BaBar initial-state radiation data. The result is obtained from the $π^+π^-/μ^+μ^-$ ratio, reducing systematic uncertainties that are in common. Unlike the previous 2009 BaBar analysis, the pion and muon contributions are separated statistically through their angular distributions. The compatibility with the previous BaBar result is quantified including statistical and systematic correlations. The new measurement is also compared with other two-pion results as a function of energy and in terms of its hadronic vacuum POLARIZATION (HVP) contribution to the muon MAGNETic anomaly. The leading-order HVP contribution of the two-pion channel in the energy range of 0.3$-$1.4 GeV is $a_μ^{ππ}=525.9\pm 3.5_\mathrm{stat}\pm3.8_\mathrm{syst}$ and $517.8\pm 2.4_\mathrm{stat}\pm3.3_\mathrm{syst}$ in units of $10^{-10}$ for the new 2026 and combined 2009 and 2026 BaBar measurements, respectively.
[abstract 47 / 53] (score: 2) - Title: A New Precise Measurement of the $e^+e^-\toπ^+π^-(γ)$ Cross Section with the Initial-State Radiation Method at BaBarAuthors: BaBar Collaboration,Comments: 56 pages, 73 figures, and 6 tablesSubjects: hep-exCreated: 2026-11-03; Updated: 2026-11-04; Datestamp: 2026-11-04
We report precise results for the $e^+e^-\to π^+π^-(γ)$ cross section in the energy range between threshold and 1.4 GeV, relevant for the hadronic vacuum POLARIZATION contribution to the muon $g-2$ prediction. Using the full 460 fb$^{-1}$ of on- and off-$Υ(4S)$ data, the cross section is derived from the ratio of $π^+π^-$ to $μ^+μ^-$ initial-state radiation (ISR) events, in which many systematic uncertainties cancel. The pion/muon separation does not rely on particle identification as in the 2009 BaBar analysis, but rather makes use of the well-known, different angular distributions in the two-particle center-of-mass system. The compatibility and correlation between the 2026 and 2009 measurements are discussed. The new measurement is also compared with other two-pion results. The leading-order hadronic contribution to the muon MAGNETic anomaly calculated using the new 2026 and combined 2009 and 2026 BaBar measurements in the energy range of 0.3$-$1.4 GeV are $525.9\pm 3.5_\mathrm{stat}\pm3.8_\mathrm{syst}$ and $517.8\pm 2.4_\mathrm{stat}\pm3.3_\mathrm{syst}$ in units of $10^{-10}$, respectively.
[abstract 48 / 53] (score: 2) - Title: Eddy currents and error fields in the toroidally segmented shell configuration aka ArmadilloAuthors: D. Abate, A. Corbioli, G. Marchiori,Comments: 15 pages, 9 figuresSubjects: physics.plasm-phCreated: 2026-11-03; Updated: 2026-11-04; Datestamp: 2026-11-04
A stream function formulation for the calculation of the eddy current distribution in a toroidally segmented conducting shell (Armadillo) is presented and verified. The governing Poisson-like equation is solved spectrally via a Discrete Sine Transform, which enforces the zero-current boundary condition at each gap exactly by construction, and the related radial MAGNETic field at the plasma surface is obtained by Biot-Savart integration. The toroidal eddy current flows in the same direction on every sector with a cosine-like poloidal distribution, while the poloidal return current, required by current continuity, peaks near each gap and reverses sign between adjacent sectors. The scaling of both components with the number of gaps is governed by the competition between the poloidal geometric scale of the shell and the toroidal segmentation scale. The transition between the two regimes is set by the aspect ratio of the device, around eight gaps for an RFX-mod2-like geometry, as predicted by the analytical wall time model of the Armadillo configuration. At the gap, the poloidal return current produces a radial field of opposite sign to the value far from the gap; the resulting non-axisymmetric error field peaks near this transition and becomes negligible for highly segmented shells. These results provide a first characterisation of the eddy currents and error fields of the Armadillo configuration, needed for future resistive wall mode and tearing mode stability analyses.
[abstract 49 / 53] (score: 2) - Title: Quark deconfinement as a natural trigger of Type-I critical collapse: BLACK HOLEs from neutron stars deemed stableAuthors: Hrishikesh Borthakur, Ritam Mallick,Comments: 11 pages, 5 figuresSubjects: astro-ph.HECreated: 2026-11-03; Updated: 2026-11-04; Datestamp: 2026-11-04
Spherically symmetric general-RELATIVISTIC simulations show that a first-order hadron--QUARK phase transition can collapse radially stable neutron stars into BLACK HOLEs, even when a stable hybrid star of the same baryon mass exists. The dynamical threshold lies $0.12\,M_\odot$ in baryon mass below the static one, so BLACK HOLEs can be lighter than the heaviest stable star. The threshold is a Type-I critical point: near it, the star lingers at an unstable hybrid star of equal baryon mass for a time set by that star's unstable mode. The effect persists within a narrower window for finite conversion rates.
[abstract 50 / 53] (score: 2) - Title: On Photon Propagation in Strong Magnetic Fields: Time Delays from PulsarsAuthors: A. W. Romero Jorge, A. Pérez Martínez, E. Rodríguez Querts, H. Pérez Rojas,Comments:Subjects: astro-ph.HE hep-phCreated: 2026-11-03; Updated: 2026-11-04; Datestamp: 2026-11-04
We study photon dispersion in the presence of a strong external MAGNETic field for propagation both perpendicular and parallel to the field, considering (i) the MAGNETized QED vacuum and (ii) a MAGNETized electron-positron medium at finite density (nonzero chemical potential). The analysis is performed in one-loop QED at finite temperature and density, and we extract POLARIZATION-dependent dispersion relations and phase velocities from the eigenmodes of the photon POLARIZATION operator. Using these phase velocities, we estimate propagation-induced time delays for photons emitted from neutron stars in the strong-field regime, adopting a simplified MAGNETosphere model with a toroidal MAGNETic field geometry and a radially varying chemical potential profile in the degenerate limit. We compare the predicted delays with observational timing constraints and discuss how strong-field QED and plasma corrections can generate measurable departures from the light cone, with potential signatures relevant for MAGNETars and modern polarimetric and timing observations. It should be noted that the time-delay estimates derived here are based on the phase velocity and serve as indicative order-of-magnitude predictions.
[abstract 51 / 53] (score: 2) - Title: First application of the optimised next neighbour cleaning to data from imaging atmospheric Cherenkov telescopesAuthors: Maria Kherlakian, Gernot Maier,Comments: Accepted for publication by A&ASubjects: astro-ph.IMCreated: 2026-11-03; Updated: 2026-11-04; Datestamp: 2026-11-04
Imaging atmospheric Cherenkov telescopes (IACTs) cameras are constantly subject to signals from the night sky background and electronic noise during event recordings. Image cleaning methods are typically employed to eliminate pixels that are mostly noise-contaminated and lack sufficient Cherenkov light. In this paper, we present the implementation of the optimised next neighbour (ONN) technique to the Very Energetic Radiation Imaging Telescope Array System (VERITAS) reconstruction pipeline. With this method, cleaning thresholds are derived in a two-parameter space, composed of the minimum total integrated charge of a cluster of pixels, $q_{\rm min}$, and by the maximum difference in the pulse arrival time within the cluster, $δ_t$. The cleaning contours in $q_{\rm min} - δ_t$ are adjusted to set a high probability of noise suppression while optimising the retention of pixels containing Cherenkov light. In comparison to the VERITAS double-pass image cleaning method, effective areas are increased at the lower energy range ($\sim$ 60 - 90 GeV) by a factor of up to $\sim$ 25. Energy thresholds are reduced by up to $\sim$ 22\%. Testing the method on Crab Nebula data resulted in an increased number of reconstructed excess events at energies < 1 TeV by a factor of up to $\sim$ 82. Finally, an increase in the differential sensitivity of VERITAS by a factor of up to $\sim$ 8 was observed at $\sim$ 20 GeV. With the addition of BDT-based $γ$/hadron separation cuts, the method improves the detection significance of a 20 hour Crab Nebula dataset, while excess event rates are enhanced by $\sim$ 16\%. In summary, the ONN image cleaning provides a reduced energy threshold and a higher rate of event reconstruction. The technique is especially advantageous for the analysis of gamma-ray sources presenting transient and soft spectra.
[abstract 52 / 53] (score: 2) - Title: Excitation factors and exceptional points of Kerr--Newman quasinormal modesAuthors: Jun-Kun Zhao, Tieguang Zi,Comments: 14 pages, 6 figures;Subjects: gr-qcCreated: 2026-11-03; Updated: 2026-11-04; Datestamp: 2026-11-04
We study excitation factors and investigate exceptional points (EPs) of Kerr--Newman quasinormal modes using the exact separated gravitoelectroMAGNETic equations. At fixed charge, the magnitudes of the excitation factors for the gravitational-led modes studied here decrease with increasing spin, whereas those for electroMAGNETic-led modes exhibit both monotonic and nonmonotonic behavior. The magnitude of the excitation factor for the first overtone can be comparable to or larger than that for the fundamental mode. We identify 42 EPs at which pairs of modes coalesce in the gravitational-led and electroMAGNETic-led sectors. Some EPs form sequences involving successive overtone pairs, with higher-overtone pairs coalescing progressively closer to the extremal limit. The additional EPs identified outside these sequences all share the same mode-pair labels as sequence members, but occur at different values of the BLACK HOLE spin and charge. These findings clarify how rotation and charge shape the relative excitation strengths of different modes and the pattern of mode coalescence in the non-Hermitian spectrum of Kerr--Newman BLACK HOLEs.
[abstract 53 / 53] (score: 2) - Title: Full-Stokes response to a stochastic gravitational-wave background in pulsar timing arrays: Fully analytic overlap reduction functions at finite distance and coherence of close pulsar pairsAuthors: Kun Zhou, Jin Li,Comments: 30 pages, 8 figuresSubjects: gr-qcCreated: 2026-11-03; Updated: 2026-11-04; Datestamp: 2026-11-04
We derive fully analytic overlap reduction functions for the full-Stokes response of a pulsar timing array to an anisotropic tensor gravitational-wave background in general relativity. The response retains both pulsar distances and their complete propagation phases. At each fixed finite sky multipole, the intensity and circular POLARIZATION responses reduce to finite combinations involving exponential integrals and logarithms, while the electric and MAGNETic linear POLARIZATION responses require only elementary functions. We evaluate all components through $\ell=8$. Symmetry separates exact nulls from additional Earth-term nulls that propagation can lift. Even an unpolarized background can produce an imaginary cross-spectrum. For a pair with three-dimensional separation $d$, the pulsar terms can remain coherent when $2πfd/c\lesssim1$, even if both pulsars are many wavelengths from Earth. A uniform approximation retaining all four Earth and pulsar terms connects this regime to the short-wavelength limit, and a rotationally invariant relation fixes the leading transverse MAGNETic response. Common-distance errors cancel from the aligned pair phase, while relative-depth errors directly affect coherence. Under Gaussian differential averaging, fixed low-multipole norms and the squared norm summed over all multipoles decay at different rates as the response shifts to higher multipoles. Published pulsar configurations illustrate the roles of distance accuracy, bandwidth, and timing fits. At fixed pointwise intensity, a POLARIZATION covariance bound and a relative-depth noise budget quantify when differencing suppresses the background. Independent sky integration and matched-accuracy benchmarks test the analytic expressions over the parameter ranges studied.
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