Current date: 2026-10-14
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Datestamp limit: 2026-10-14 (0 days ago)
Created/updated limit: 2026-10-07 (7 days ago)
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Scoring abstracts
Number of records retrieved: 1300
Keyword score statistics
score 11 -- 2 abstracts
score 10 -- 1 abstracts
score 8 -- 1 abstracts
score 7 -- 2 abstracts
score 6 -- 2 abstracts
score 5 -- 3 abstracts
score 4 -- 7 abstracts
score 3 -- 14 abstracts
score 2 -- 31 abstracts
in total -- 63 abstracts
Articles that appeared on 2026-10-14
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[abstract 1 / 63] 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, in pressSubjects: astro-ph.HECreated: 2026-10-12; Updated: 2026-10-14; Datestamp: 2026-10-14
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 2 / 63] Wow! (score: 11) - Title: First Detection of Radio Polarization During Jet Formation in the Changing-Look AGN 1ES 1927+654Authors: Onic I. Shuvo, Eileen T. Meyer, Sibasish Laha, Agniva Roychowdhury, Dev R. Sadaula, Tracy E. Clarke, Wendy M. Peters, Mitchell C. Begelman, Markos Georganopoulos, Rostom Mbarek, Amelia M. Hankla, Alexander Philippov, Navin Sridhar,Comments: 22 pages, 10 figures, 2 tables. Accepted for publication in ApJSubjects: astro-ph.HE astro-ph.GACreated: 2026-10-10; Updated: 2026-10-14; Datestamp: 2026-10-14
We present a multiwavelength radio study of the changing-look AGN 1ES 1927+654 following its renewed X-ray brightening since mid-2022, combining VLBA imaging with multi-band and time-resolved VLA observations. Our main results are: (i) VLBA observations continue to reveal the bipolar JET structure first reported in Meyer et al. (2025), with new X-band detections confirming the morphology at larger separation and K-band imaging revealing a bridge of emission consistent with a continuous outflow; (ii) the VLBA core exhibits a GHz-peaked spectrum, and VLA/VLITE observations from 340 MHz to 45 GHz show emission from an inhomogeneous SYNCHROTRON source, self-absorbed below ~3 GHz and optically thin above; (iii) VLA and VLBA flux densities are consistent above 8 GHz, indicating emission dominated by a compact core; (iv) linear POLARIZATION is detected above ~3 GHz, with fractional POLARIZATION increasing with frequency from ~0.2% to ~6% and EVPAs exhibiting non-linear lambda^2 behavior; (v) long-term VLA X-band monitoring reveals a large, smooth rotation of the EVPA of ~137 degrees over ~81 days in 2026, followed by a partial return, at stable total intensity and suppressed fractional POLARIZATION <~1.4%, consistent with a propagating disturbance crossing the compact emitting region; and (vi) circular POLARIZATION is not detected at any epoch. These observations demonstrate that 1ES 1927+654 has transitioned from an X-ray-dominated, non-JETted state to a radio-loud AGN (Laha et al. 2025) hosting a newly launched RELATIVISTIC JET, a unique laboratory for studying JET birth and early MAGNETic field evolution.
[abstract 3 / 63] Wow! (score: 10) - Title: Multi-Period FERMI-LAT and LHAASO Constraints on Axion-Like Particles from Mrk 421 via $χ^2$ Profile Likelihood with Gaussian Copula CorrelationAuthors: Longhua Qin, Jiancheng Wang, Chuyuan Yang, Huaizhen Li, Ao Wang, Weiwei Na, Hushan Xu, Zhongtao Han, Xiaogu Zhong, Zunli Yuan, Yubin Li, Guangbo Long,Comments: Already accepted by Physical Review DSubjects: astro-ph.HECreated: 2026-10-11; Updated: 2026-10-14; Datestamp: 2026-10-14
We present a joint multi-period analysis of axion-like particles (ALPs) using five sets of simultaneous FERMI-LAT and LHAASO observations of the TeV BLAZAR Mrk~421. Photon-ALP oscillations are calculated self-consistently together with EBL absorption for two representative JET emission models: a two-zone hybrid model and a single-zone hadronic model. To account for weak correlations among different observational epochs, we adopt a $χ^2$-based profile analysis combined with a Gaussian copula ($ρ=0.03$). Nuisance parameters are optimized under the no-ALP hypothesis before profiling the ALP parameters $m_a$ and $g_{aγ}$. In the low-mass regime ($m_a\lesssim1$\,neV) we obtain a 95\% CL upper limit of $g_{aγ}=6.35\times10^{-13}\,\mathrm{GeV}^{-1}$. Over the full mass range $0.1$--$500$\,neV, the most conservative 95\% CL upper limits are $g_{aγ}<6.69\times10^{-12}\,\mathrm{GeV}^{-1}$ (two-zone) and $g_{aγ}<7.37\times10^{-12}\,\mathrm{GeV}^{-1}$ (single-zone). Variations of the EBL template, the Galactic and intergalactic MAGNETic-field models, the spectral binning, and residual instrumental systematics change these limits by only a few percent. The JET MAGNETic field is the leading systematic and can shift the low-mass bound by a factor of a few; only a substantially weaker single-zone field degrades the constraint by about an order of magnitude. The analysis framework developed here provides a statistically consistent approach for future ALP searches with multi-messenger gamma-ray data.
[abstract 4 / 63] Wow! (score: 8) - Title: Revisiting the Multiwavelength Data of GRB 240825A: Implications for a Two-Stage Central Engine and a Dusty EnvironmentAuthors: Ren-Jie Xiong, Zi-Qi Wang, Xiao-Li Huang, En-Wei Liang,Comments: 16 pages, 5 figures, 3 tables. Accepted for publication in ApJSubjects: astro-ph.HECreated: 2026-10-11; Updated: 2026-10-14; Datestamp: 2026-10-14
Reanalyzing the multi-wavelength data of GRB 240825A, we identify two distinct prompt-emission episodes, i.e. an early, spectrally soft plateau and a subsequent bright, spectrally hard gamma-ray pulse. We show that this signature is consistent with a two-stage central engine model, in which the early soft plateau is powered by the dipolar spin-down radiation of a transient proto-MAGNETar, while the later hard pulse arises from a RELATIVISTIC JET launched by fallback accretion onto the nascent BLACK HOLE via the Blandford-Znajek mechanism. Adopting simulation-motivated initial BLACK HOLE (BH) masses ($M_{\rm BH,0}$) and spins ($a_0$), our fits to the second episode yield total masses supplied to the post-collapse disk of $M_{\rm fb}=0.45$--$0.96 M_\odot$, fallback radii of $r_{\rm fb}=16.9$--$17.6 r_g$, and characteristic fallback timescales of $t_{\rm fb}=0.13$--$0.25$ s. The corresponding maximum inner accretion rates range from $0.18$ to $0.70 M_\odot \mathrm{s}^{-1}$, which is sensitive to $a_0$. Joint spectral fits with optical-X-ray afterglow data reveal a coupled temporal evolution of dust extinction and equivalent hydrogen column density. Incorporating this extinction evolution, an external forward-reverse shock model in a wind-like medium can account for the radio-to-GeV band afterglow data. Although ambient dust and the bright host galaxy may obscure any associated SUPERNOVA, late-time optical reddening remains compatible with a SUPERNOVA contribution. Applying the empirical relation between the prompt spectral peak energy and the SN peak bolometric magnitude gives an illustrative estimate of $M_{\rm bol,peak}=-19.46\pm0.35$ mag for a putative associated SN. These results support a two-stage evolution of the central engine and variable dusty environment of GRB 240825A, which provides insights into the nature of its progenitor.
[abstract 5 / 63] Wow! (score: 7) - Title: Widespread steep X-ray spectra of luminous $z\simeq5.85-7.6$ QUASARs and their implications for future X-ray surveysAuthors: A. Tortosa, L. Zappacosta, E. Piconcelli, I. Saccheo, G. Lanzuisi, E. Bertola, F. Vito, M. Bischetti, M. Brazzini, M. Castellano, S. Carniani, A. Comastri, S. Gallerani, R. Gilli, F. La Franca, P. Madau, R. Maiolino, G. Miniutti, B. Musiimenta, C. Piscitelli, F. Salvestrini, F. Tombesi, R. Tripodi, C. Vignali, M. Volonteri, A. Bongiorno, L. Borrelli, M. Brusa, I. V. Chilingaria, F. Civano, S. Cristiani, V. D'Odorico, D. De Cicco, C. Done, M. Elvis, X. Fan, C. Feruglio, F. Fiore, A. Grazian, M. Guainazzi, F. Haardt, A. Luminari, N. Menci, R. Middei, F. Nicastro, M. Paolillo, M. Perna, S. Puccetti, R. Schneider, V. Testa, R. Valiante, L. Vallini, E. Vanzella, G. Vietri,Comments: Revised version submitted to A&ASubjects: astro-ph.HE astro-ph.GACreated: 2026-10-12; Updated: 2026-10-14; Datestamp: 2026-10-14
Luminous QUASARs (QSOs) at the Epoch of Reionization (EoR, $z\gtrsim6$) host billion-solar-mass BLACK HOLEs assembled within the first Gyr of cosmic time. Their X-ray emission probes the innermost accreting regions and constrains the physical state of the corona during early supermassive BLACK HOLE (SMBH) growth. Previous results from the HYPerluminous QUASARs at the Epoch of ReionizatION (HYPERION) sample of $z \gtrsim 6$ QSOs, powered by the most rapidly accreted SMBHs, suggested a link between X-ray spectral slope and long-term growth efficiency. We test whether the steep X-ray spectra of luminous z>6 QSOs are a general property of early SMBH growth or a peculiarity of the most efficiently grown SMBHs, using a sample extended mainly to the lowest growth efficiencies. We analysed the largest and most X-ray sensitive sample of 28 luminous QSOs at $z \simeq 5.85-7.56$ (26 used in the correlation analysis), combining HYPERION targets, luminous non-HYPERION sources, and QSOs powered by moderately accreting SMBHs newly observed in our XMM-Newton Large Programme. We re-derived BLACK HOLE masses and growth indicators for the entire sample homogeneously, incorporating the latest JWST-based spectroscopic measurements to ensure the most consistent and high-quality characterization across all targets. We found no statistically significant correlation between coronal spectral parameters and BH growth indicators: luminous $z \gtrsim 6$ QSOs systematically show steep X-ray continua, with high photon indices and/or low high-energy cutoffs, consistent with cold coronae, possibly linked to rapid accretion. Finally, if steep X-ray slopes are common among early AGN, they may significantly reduce count rates, at fixed intrinsic luminosity, in future surveys of the EoR, affecting the detectability of steep-spectrum X-ray sources and thus the census of the early AGN population.
[abstract 6 / 63] Wow! (score: 7) - Title: A GeV Gamma-Ray Spectral Excess in the FERMI Blazar 4FGL J0136.5+3906Authors: Shi-Ju Kang, Yue Yin, Yong-Gang Zheng, Qingwen Wu, Junhui Fan,Comments: Published in ApJLSubjects: astro-ph.HECreated: 2026-10-10; Updated: 2026-10-14; Datestamp: 2026-10-14
We report the detection of a $\sim${19} GeV gamma-ray spectral excess (peak energy in observer frame) at $\sim$5.7$σ$ significance (3 degrees of freedom, without correction for trials and the look-elsewhere effect) in the FERMI-LAT data of the BLAZAR 4FGL J0136.5$+$3906, based on $\sim${17} years of observations. The excess manifests as a distinct bump-like feature in the 100 MeV$-$1 TeV spectrum, with a flux of $\sim$3.6$\rm \times10^{-10}~ph~cm^{-2}~s^{-1}$. No similar feature is detected in nearby sources or background regions. The origin of this signal cannot be explained by standard BLAZAR emission models and remains unknown. This Letter presents the observational finding without providing a definitive physical interpretation.
[abstract 7 / 63] Yes (score: 6) - Title: Potential periodic signals in BLAZARs: significance, forecasting, and deep learningAuthors: M. A. Hashad, A. Hammad, Amr A. EL-Zant,Comments:Subjects: astro-ph.HECreated: 2026-10-10; Updated: 2026-10-14; Datestamp: 2026-10-14
Blazars exhibit variable emission on diverse timescales. Some light curves show signs of quasiperiodic oscillations (QPOs), which may encode clues regarding the physical processes behind the emission or point to supermassive binary BLACK HOLEs. We analyzed five BLAZARs with previously reported high significance year-long QPOs, applying the Lomb-Scargle periodogram and Weighted Wavelet Z-transform methods to FERMI-LAT data up to early 2025. We furthermore examined an additional source (PKS 0139-09), where nascent QPO may be present. As the light curves showed longer term trends, we detrended the data using an STL decomposition, which often revealed a large seasonal component. We find that detrending generally leads to an increase in the strength of the QPO signal. However, except for PG 1553+113, where a clearly persistent QPO signal is present, we detect transience on a timescale of $\lesssim$4000 days. We then forecast the light curves over the following four years, using a traditional statistical method as well as a Transformer-based deep learning model. Applied to a test set, the latter showed significant success in predicting behavior that seems unexpected from simple inspection of the past data. Analyzing the extended time series suggests a markedly weaker QPO signals over the coming years in cases where the transient behavior appears near the end of the observational data. In contrast, in the nascent candidate QPO source (PKS 0139-09) the signal is expected to strengthen significantly. These predictions, which may reflect the physical origin of the QPOs, can be tested against future data.
[abstract 8 / 63] Yes (score: 6) - Title: Morphology-aware periodicity searches in FERMI-LAT BLAZARsAuthors: Aaron A. Maldonado, Alberto Domínguez, Adithiya Dinesh, Alba Rico, Pablo Peñil, Sara Buson, Marco Ajello,Comments: Substantial revision, results and conclusions changed. Submitted to A&ASubjects: astro-ph.HE astro-ph.GACreated: 2026-10-12; Updated: 2026-10-14; Datestamp: 2026-10-14
Standard periodicity searches in ACTIVE GALACTIC NUCLEi assume sinusoidal modulation, whereas gamma-ray BLAZAR emission often features asymmetric flares and localized bursts. We investigate how periodicity significance in FERMI-LAT light curves depends on intra-cycle morphology and data-quality cuts. We analyze 101 seven-day binned light curves from the FERMI-LAT Light Curve Repository (LCR) using the Fast Template Periodogram with sinusoidal, Gaussian burst, and empirical asymmetric templates. Significances are calibrated with red-noise simulations including a Poisson noise floor. A Random Forest classifier scores sources using periodogram, phase-coherence, and period-stability features. Unconstrained likelihood fits in a few bins flatten the periodogram and make the simulated null effectively white. After quality cuts, three sources exceed a per-source significance of 3 sigma, versus 0.14 expected by chance. One is the established candidate PG 1553+113, but none reaches 3 sigma after correcting for the 101 light curves searched. Template choice substantially affects significance: for 4FGL J0102.8+5824, it is 0.24 sigma with a sinusoid and 3.85 sigma with a Gaussian burst. Such a gain is expected for about one source in simulated noise, while about 40 percent of sources favor a sinusoid. The significance distribution has a heavier upper tail than the Gaussian null predicts, consistent with flares. We report no new periodicity detection. Non-sinusoidal templates complement sinusoidal searches, but a large significance gain alone does not establish periodicity. The classifier also responds to isolated flares, indicating that the null does not fully capture flare behavior. Our results agree with recent systematic searches. Applying the LCR convergence criterion, supplemented by a consistency check, is important for periodicity searches, especially with seven-day bins.
[abstract 9 / 63] Yes (score: 5) - Title: Search for Gamma-ray emission from Abell 119 galaxy cluster using INTEGRAL/ISGRI, COMPTEL, and DAMPE dataAuthors: Siddhant Manna, Shantanu Desai,Comments: 11 pages, 4 figures. Published in the Open Journal of AstrophysicsSubjects: astro-ph.HE astro-ph.COCreated: 2026-10-09; Updated: 2026-10-14; Datestamp: 2026-10-14
We present a comprehensive search for non-thermal high-energy $γ$-ray emission from the nearby merging galaxy cluster Abell~119 ($z=0.044$) using archival observations spanning over seven decades in photon energy. Our analysis combines hard X-ray data from INTEGRAL/ISGRI (30--100~keV), MeV $γ$-ray observations from COMPTEL (0.75--30~MeV), and GeV--TeV data from the DArk Matter Particle Explorer (DAMPE; 3~GeV--1~TeV). No statistically significant emission is detected at the cluster position in any energy band. In the hard X-ray regime, we derive a $3σ$ upper limit of $F_{30-100\,\mathrm{keV}} \lesssim 8.5 \times 10^{-11}$~erg~cm$^{-2}$~s$^{-1}$ from ISGRI mosaic imaging. Reanalysis of archival COMPTEL data yields 95\% confidence-level upper limits ranging from $\sim 9 \times 10^{-11}$ to $\sim 8 \times 10^{-10}$~erg~cm$^{-2}$~s$^{-1}$ across 0.75--30~MeV. In the GeV--TeV range, DAMPE \rthis{places upper limits on the} differential energy flux to $\sim 10^{-12}$--$10^{-10}$~erg~cm$^{-2}$~s$^{-1}$ (95\% confidence level). These results provide independent multi-band constraints on the reported GeV excess from recent FERMI-LAT studies. While our DAMPE limits do not exclude the flux levels claimed in those analyses, the absence of confirmation across keV--MeV--GeV bands indicates that any non-thermal emission from Abell~119 remains tentative.
[abstract 10 / 63] Yes (score: 5) - Title: The plunging region of thin accretion discs across the BLACK HOLE spin rangeAuthors: Jake Rule, Andrew Mummery, Steven Balbus, James M. Stone, Lizhong Zhang,Comments: 17 pages, 10 figures, accepted for publication in MNRASSubjects: astro-ph.HECreated: 2026-10-12; Updated: 2026-10-14; Datestamp: 2026-10-14
We compute and test analytic models for the plunging region dynamics, thermodynamics, and MAGNETic fields against dedicated 3D global general RELATIVISTIC MAGNETohydrodynamics (MHD) simulations of thin accretion discs around BLACK HOLEs across the spin range, using the code {\tt ATHENAK}. We find that the dynamics of the plunging fluid closely resembles that of a gravity-dominated geodesic plunge, with the best agreement at low spins. Additionally, we find good agreement between the thermodynamic framework and the simulated quantities across the spin range. Finally, we develop a new model for the MAGNETic fields in the plunging region that assumes a fixed geodesic inflow, into which the MAGNETic fields are frozen. Overall, our simulations are in good concordance with this model, albeit with some discrepancies that suggest a degree of non-ideal MHD dissipation. In addition, we investigate how the MHD stresses in the plunging region depend on the BLACK HOLE spin, interpreting our results through the lens of our flux-freezing model. We find that the magnitude of the stress increases as the BLACK HOLE spin is increased in the prograde direction. This question is of particular importance for observers who wish to determine the BLACK HOLE spin from X-ray measurements of the inner accretion disc, since a low-stress, high-spin solution is degenerate with a high-stress, low-spin solution. The spin-stress relationship that we report is approximately orthogonal to the contour of degenerate spin-stress pairings, indicating that the degeneracy is not fundamental. We show this explicitly for the case of M33 X-7.
[abstract 11 / 63] Yes (score: 5) - Title: Cosmic Colliders in Binary Blazars Probing Ultra-High-Energy Particle PhysicsAuthors: Giorgio Galanti,Comments: 32 pages, 15 figuresSubjects: hep-ph astro-ph.HE hep-thCreated: 2026-10-12; Updated: 2026-10-14; Datestamp: 2026-10-14
While terrestrial COLLIDERs and fixed-target cosmic-ray interactions are bounded at center-of-mass (CM) energies $\sqrt{s} \lesssim \mathcal{O}(10^5)\,\text{GeV}$, we demonstrate that bound sub-parsec binary BLAZARs form broad-band, beam-beam hadronic ``Cosmic Colliders'', overcoming such limitation. Driven by modest JET misalignments ($θ_{\rm mis} \sim 1^\circ - 6^\circ$), co-streaming proton beams collide at CM energies reaching $\sqrt{s} \sim 10^{10}\,\text{GeV}$ - six orders of magnitude above the Large Hadron Collider. Operating in a strictly optically thin regime ($τ_{pp} \ll 1$), the system performs a continuous CM energy scan, probing asymptotic QCD scaling, gluon saturation, and Froissart unitarity, while opening a possible high-sensitivity window into physics beyond the Standard Model. Secondary PeV-EeV neutrinos and sub-TeV $γ$-rays fall directly within reach of current and planned observatories such as LHAASO, CTAO, IceCube, and GRAND, establishing binary BLAZARs as laboratories for physics at the ultimate energy limit.
[abstract 12 / 63] Yes (score: 4) - Title: The link between extreme particle acceleration and X-ray binary JETsAuthors: Laura Olivera-Nieto, Fraser J. Cowie, Sera Markoff, Rob Fender, Justine Crook-Mansour,Comments: accepted for publication in A&ASubjects: astro-ph.HECreated: 2026-10-12; Updated: 2026-10-14; Datestamp: 2026-10-14
The detection of multi-TeV radiation from a handful of black-hole X-ray binaries (BHXRBs) has positioned the source class as promising candidate to explain the cosmic-ray flux in the PeV energy range. To determine what distinguishes the systems detected in the gamma-ray range from the rest of the population, we build on existing catalogues of BHXRBs by including information on the radio and gamma-ray emission from these systems. We then compare the $>100$ TeV gamma-ray luminosity to different properties of the systems and evaluate the strength of the (rank) correlation between them. Additionally, we compare the distribution of BHXRBs with the positions of unassociated gamma-ray sources in the 1LHAASO and 1HGPS catalogues. We find no correlation with the mass of the compact object, the companion mass or the inclination angle. Instead, we find evidence for a strong correlation between the gamma-ray luminosity and the radio and hard-state X-ray luminosities in our sample. The limited number of gamma-ray detections means that this correlation cannot yet be claimed as statistically significant. We find indications that a high (>20\%) duty cycle (defined as fraction of time spent in outburst) might be a requirement for $>100$ TeV gamma-ray loudness. We find significant evidence ($>3σ$) that BHXRBs are located near unassociated gamma-ray sources in the region of the sky not covered by LHAASO. This evidence is only significant when comparing to BHXRBs with a reported detection in the radio band. We conclude that radio-bright BHXRBs with a high duty cycle are more likely to be detected as gamma-ray sources than sources which are not detected in the radio band or those with low duty cycles. This result suggests that the particles responsible for the gamma-ray emission are associated with the JETs, either accelerated within them or via their interaction with their surroundings.
[abstract 13 / 63] Yes (score: 4) - Title: Physics-Informed Neural Networks and Data-Driven Models for GRB X-ray Light-Curve Gap ReconstructionAuthors: Ayush Garg, Ritik Kumar, Maria G. Dainotti, Vipul Sharma, Amit Shukla, Dieter H. Hartmann,Comments: 36 pages, 6 figures, 7 tables, journal paperSubjects: astro-ph.HE astro-ph.COCreated: 2026-10-12; Updated: 2026-10-14; Datestamp: 2026-10-14
Temporal gaps in SWIFT-XRT X-ray afterglows of GAMMA-RAY BURSTs (GRBs) limit how precisely the standard empirical plateau function constrains three parameters: the plateau end time $T_a$, the plateau flux $F_a$, and the post-plateau decay index $α$. These parameters underpin the luminosity-time and fundamental-plane correlations of GRB plateaus so that smaller measurement uncertainties can improve the statistical power of GRBs as cosmological probes. As the fifth study in a series on light-curve reconstruction, this work benchmarks four models on a parent sample of 545 SWIFT-XRT GRBs: a Physics-Informed Neural Network (PINN) with seven afterglow-motivated priors, ReFANN, a Siamese dual-branch network with Monte Carlo dropout, and Polynomial Quantile Regression (PQR). All four reduce the fractional uncertainties in $\log T_a$, $\log F_a$, and $α$ relative to the original observations. The PINN with a broken power-law prior gives the largest reductions ($\sim$41-49\%), at a higher outlier rate ($\sim$15-20\%), while ReFANN, Siamese network and PQR give more modest reductions ($\sim$19-27\%) with outlier fractions $\lesssim$4\%, across a wider range of light-curve morphologies. A reduced-$χ^2$ prior-selection scheme recovers a morphological classification consistent with independent labelling, though it does not match the best single-prior reduction. Together, these results provide a systematic benchmark of physics-informed and data-driven reconstruction strategies for irregularly sampled GRB afterglows.
[abstract 14 / 63] Yes (score: 4) - Title: Searching for Nearby Supermassive Black Hole Binaries with GRAVITYAuthors: GRAVITY Collaboration, K. Abd El Dayem, N. Aimar, A. Berdeu, J. -P. Berger, G. Bourdarot, W. Brandner, Y. Cao, C. Correia, Q. D'Amato, R. Davies, D. Defrère, A. Drescher, F. Eisenhauer, M. Fabricius, H. Feuchtgruber, S. Flesch, N. M. Förster Schreiber, A. Foschi, Q. Fournier, P. Garcia, R. Garcia Lopez, R. Genzel, S. Gillessen, F. Gonté, X. Haubois, S. F. Hönig, L. C. Ho, M. Houllé, S. Joharle, J. Kammerer, A. Kaufer, P. Kervella, J. Kolb, L. Kreidberg, L. Labadie, S. Lacour, O. Lai, R. Laugier, J. B. Le Bouquin, J. Leftley, R. Li, K. Li, B. Lopez, D. Lutz, F. Mannucci, F. Mang, A. Mérand, F. Millour, M. Montargès, N. Morujão, H. Nowacki, M. Nowak, S. Oberti, J. Osorno, T. Ott, C. Paladini, S. Pappert, T. Paumard, K. Perraut, G. Perrin, R. Petrov, P. O. Petrucci, N. Pourré, S. Rabien, D. C. Ribeiro, S. Robbe-Dubois, M. Sadun Bordoni, J. Sanchez-Bermudez, J. Sauter, M. Scialpi, J. Scigliuto, J. Shangguan, T. Shimizu, F. Soulez, C. Straubmeier, E. Sturm, M. Subroweit, C. Sykes, L. J. Tacconi, P. Thévenet, I. Urso, F. Vincent, J. Woillez, G. Zins,Comments: 19 pages, 10 figuresSubjects: astro-ph.GACreated: 2026-10-09; Updated: 2026-10-14; Datestamp: 2026-10-14
We present a systematic interferometric search for close supermassive BLACK HOLE (SMBH) binaries in 20 nearby type 1 ACTIVE GALACTIC NUCLEi (AGN) observed with VLTI/\grav. We investigate parsec-scale asymmetric emission by modeling the squared visibilities and closure phases with a single circular Gaussian component plus a background point source for the central AGN, and searching for additional compact companions through grid-based binary models. The robustness of the search is validated using injection-recovery simulations and point-spread-function diagnostics. Several features are identified in the initial significance maps, but only one candidate out of 20 shows a persistent compact asymmetry, corresponding to an observed incidence of $5\%$. If NGC~3783 is interpreted as a binary AGN, we derive a Poissonian one-sided $1σ$ upper limit of $f_{\rm bin}<16.5\%$ for GRAVITY-detectable binaries among bright nearby AGN (K<12.5) at separations of $\sim1$-$100$~pc. Conversely, if the observed asymmetry in NGC~3783 is associated with asymmetric circumnuclear dust emission, the corresponding upper limit on the binary fraction is $f_{\rm bin}<9.2\%$. We compare these results with predictions from the Horizon-AGN simulation, finding comparable binary fractions. We also noted that the expected fraction strongly depends on the assumed distribution of individual SMBH accretion rates within binaries, which is currently unresolved in cosmological models. Our results demonstrate the potential of infrared interferometry to identify parsec-scale binary AGN candidates and motivate future GRAVITY+ observations to expand the sample and follow up known candidates, helping to confirm their nature and distinguish genuine binaries from asymmetric nuclear structures.
[abstract 15 / 63] Yes (score: 4) - Title: Magnetar X-ray flares as elementary RECONNECTion events in a self-organized critical MAGNETosphereAuthors: Sheng-Lun Xie, Yi Zhao, Wen-Long Zhang, Chen-Wei Wang, Yun-Wei Yu, Shao-Lin Xiong,Comments: Accepted for publication in ApJLSubjects: astro-ph.HECreated: 2026-10-10; Updated: 2026-10-14; Datestamp: 2026-10-14
Magnetar bursts are commonly attributed to MAGNETic energy release, yet the physically relevant dissipation unit has remained uncertain. Here we argue that this unit is not the burst as conventionally defined, but the short substructures within bursts, namely MAGNETar X-ray flares (MXFs). Using 789 MXFs from SGR~J1935+2154, we show that their waiting times separate into two components, interpreted as reflecting clustered intra-episode events and longer inter-episode intervals, that their proxy emission measure and temperature exhibit distinct rising and declining trends, and that their energy release scale (ERS) proxy distribution has a high-end slope in the same statistical regime as solar and stellar flares. Combined with the previously measured MXF duration slope, these results identify MXFs as a three-dimensional fractal-diffusive self-organized critical (FD-SOC) system with $β_{\rm diff}\simeq2$, implying RECONNECTion avalanches that expand linearly through an active MAGNETosphere. We infer that MAGNETar active episodes are global unloading states assembled from many elementary flares. Magnetar X-ray flares are therefore the physically relevant units for MAGNETar outburst statistics and for connecting MAGNETar high-energy activity to other impulsive phenomena.
[abstract 16 / 63] Yes (score: 4) - Title: Toward a Multimodal Foundation Model for Plasma State ReconstructionAuthors: Bin Xia, Chuanfei Dong, Boting Li, Yilan Qin, Zikang Xie, Sung Hyun Son, Adam J. Stanier, Jongsoo Yoo, Hantao Ji, Ahmed Diallo, Han Ding, John Wise,Comments: Accepted at the NeurIPS 2026 Workshop on Physical World AI (PhysWorldAI). 15 pages, 5 figures, 5 tablesSubjects: cs.LG physics.plasm-phCreated: 2026-10-10; Updated: 2026-10-14; Datestamp: 2026-10-14
Plasma experiments observe coupled physical states through sparse, heterogeneous, and incomplete diagnostics. We present a proof of concept toward a multimodal foundation model for plasma state reconstruction during MAGNETic RECONNECTion, motivated by the Facility for Laboratory Reconnection Experiments (FLARE). Using 250 synthetic VPIC simulations at fixed reference electron beta $β_{e0}=0.2$, with 225 training runs and 25 disjoint validation runs, we train a 5.5M-parameter residual 3D U-Net to reconstruct three MAGNETic-field components and electron density from incomplete observations. The model combines spatial-only pooling, which preserves all 24 temporal frames, with global spatiotemporal self-attention and rotary positional encoding. Independently masking MAGNETic and density modalities across random, grid, block, and temporal patterns enables sparse sensing, cross-modal completion, density super-resolution, and temporal completion with a single set of weights and no task-specific retraining. With density fully hidden, just 0.1% MAGNETic spatial visibility reduces median density NRMSE from approximately 0.9 to 0.1. Conversely, observed density improves current-density reconstruction when MAGNETic data are absent or extremely sparse. With no MAGNETic observations, roughly 1% density visibility approaches the density reconstruction accuracy achieved with fully observed MAGNETic fields, although current structure remains more dependent on direct MAGNETic measurements. Full MAGNETic conditioning also stabilizes completion of missing future density frames. These results demonstrate bidirectional cross-modal predictive coupling within this simulation regime. Generalization across plasma regimes or to experimental measurements remains untested.
[abstract 17 / 63] Yes (score: 4) - Title: Direct Observational Constraint on Upstream Magnetic Field Amplification Reveals the Particle Acceleration Limit in a Supernova RemnantAuthors: Yuya Kawabata, Takaaki Tanaka, Hiromasa Suzuki, Tsuyoshi Inoue,Comments: 17 pages, 6 figures. Published in Communications PhysicsSubjects: astro-ph.HECreated: 2026-10-12; Updated: 2026-10-14; Datestamp: 2026-10-14
The origin of Galactic COSMIC RAYs up to the knee energy (PeV) remains a long-standing open question in astrophysics. Supernova remnant shocks are leading candidates for accelerating particles to PeV energies, yet this requires strong MAGNETic field amplification in the upstream region to confine the highest energy particles. Despite its importance, the upstream MAGNETic field strength has long lacked direct observational constraints. Here we report the observation of numerous SYNCHROTRON X-ray hotspots extending into the upstream of the SUPERNOVA remnant RX J1713.7$-$3946 in archival Chandra data. These hotspots show spatial and temporal properties consistent with SYNCHROTRON emission from secondary electrons produced by hadronic interactions between accelerated protons and dense molecular clumps. Using the spatial extent of these upstream hotspots as a physical scale, we estimate the proton diffusion length to be $\sim 1~\mathrm{pc}$. This measurement provides a constraint on the upstream MAGNETic field strength of $\sim 10~μ\mathrm{G}$, which is consistent with recent simulations of Bell-instability-driven MAGNETic field amplification. Our results indicate that the current amplification is insufficient to reach PeV energies, explaining the observed TeV gamma-ray spectral cutoff and providing a diagnostic for assessing PeVatron capability in stellar shocks.
[abstract 18 / 63] Yes (score: 4) - Title: A Quest for Changing-State AGNsAuthors: Kasra Mokhtarpour, Vicki Sarajedini,Comments: 21 pages, 10 figure, 3 tables and 14 numbered equations. Submitted to AAS JournalsSubjects: astro-ph.GA astro-ph.HE astro-ph.IMCreated: 2026-10-12; Updated: 2026-10-14; Datestamp: 2026-10-14
We use Gaia Data Release 3 (DR3) light curves to identify photometrically selected changing-state ACTIVE GALACTIC NUCLEus (CSAGN) candidates. We employ unsupervised deep learning and anomaly detection methods to identify unusual patterns of variability in the light curves of 872,228 AGNs with known variability. We find that 8,504 light curves show anomalous behavior. Among these, 682 sources show evidence for two-state photometric behavior during the Gaia DR3 observing baseline. These 682 CSAGN candidates were selected using an automated statistical pattern recognition approach based on Gaussian mixture models (GMMs) to identify sources whose magnitude distributions are consistent with two preferred brightness levels, substantially reducing the need for human visual inspection in selecting the CSAGN candidates. The candidates tend to have fainter absolute magnitudes and lower redshifts than the non-anomalous Gaia variable AGN sample, suggesting that some may be accreting at lower rates. Our approach builds a large candidate sample with less reliance on human visual selection. Follow-up observations of these sources can help identify what drives changing-state transitions and clarify their connection to accretion-disk physics and supermassive BLACK HOLE (SMBH) fueling.
[abstract 19 / 63] (score: 3) - Title: Hard X-ray luminosity functions of cataclysmic variables: Joint SWIFT/BAT and Gaia dataAuthors: Valery F. Suleimanov, Victor Doroshenko, Klaus Werner,Comments: 10 pages, 4 figures, 4 tables. Published in MNRAS in 2022. A typo in Eq. (3) has been correctedSubjects: astro-ph.HECreated: 2026-10-12; Updated: 2026-10-14; Datestamp: 2026-10-14
Cataclysmic variables (CVs) are the most numerous population among the Galactic objects emitting in hard X-rays. Most probably, they are responsible for the extended hard X-ray emission of the Galactic ridge and the central Galactic regions. Here we consider the sample of CVs detected in the all-sky hard X-ray SWIFT/BAT survey which were also detected by Gaia and thus have reliable distance estimates. Using these data, we derive accurate estimates for local number density per solar mass ($ρ_M = 1.37^{+0.3}_{-0.16} \times 10^{-5} M_\odot^{-1}$) and luminosity density per solar mass ($ρ_L = 8.95^{+0.15}_{-0.1} \times 10^{26} erg\, s^{-1} M_\odot^{-1}$) for objects in the sample. These values appear to be in good agreement with the integrated Galactic ridge X-ray emission and Nuclear Stellar Cluster luminosities. Analysis of the differential luminosity functions $dρ_M/d(\log_{10} L_x)$ and $dρ_L/d(\log_{10} L_x)$ confirms that there are two populations of hard X-ray emitting CVs. Intermediate polars dominate at luminosities $L > 10^{33} erg\, s^{-1}$, whereas non-MAGNETic CVs and polars are much more numerous but have lower luminosities on average. As a consequence, the contribution of these populations to the observed hard X-ray luminosity is almost equivalent.
[abstract 20 / 63] (score: 3) - Title: X-ray spectroscopy method of white dwarf mass determination in intermediate polars. External systematic uncertaintiesAuthors: V. F. Suleimanov, L. Ducci, V. Doroshenko, K. Werner,Comments: 13 pages, 14 figures, Published in A&A, a link to the new model grid in XSPEC has been addedSubjects: astro-ph.SR astro-ph.HECreated: 2026-10-12; Updated: 2026-10-14; Datestamp: 2026-10-14
The masses of white dwarfs (WDs) in intermediate polars (IPs) can be determined from the shape of their hard X-ray spectra. Here we study the importance of all possible systematic uncertainties in this X-ray spectroscopy method, including finite radii and rotation of MAGNETospheres, finite accretion column height and accretion-flow inclination relative to the WD surface. We also investigate the importance of accretion-heated envelopes on WD surfaces in IPs which are increasing WD radii. Their presence changes the commonly used mass-radius relation for cold white dwarfs. As a first approximation we use thick ($10^{-4}M_\odot$) hydrogen envelope models with a surface temperature of 30 kK. We present a new model grid of hard X-ray spectra of high-luminous IPs computed among other things with using a new mass-radius relation. This grid is used for fitting SWIFT/BAT spectra of 47 IPs. The average WD mass in this sample is 0.82 $M_\odot$ and coincides with the average WD mass in cataclysmic variables obtained by optical methods. This means that the calculated hard X-ray spectra and the assumptions made that the MAGNETospheric radii in IPs are close to the corotation radii, and the relative heights of the accretion columns are small are basically correct, because most IPs have high luminosities. But this universal grid (as well as previous universal grids) cannot give correct results for the low-luminous IPs with probably relatively tall accretion columns on the WD surfaces. Such IPs have to be investigated with individual accretion column models.
[abstract 21 / 63] (score: 3) - Title: GA-NIFS: sRMS, a new method for disentangling resolved and unresolved emission in integral field spectroscopy. Application to distant QUASARsAuthors: Michele Perna, Santiago Arribas, Carlota Prieto-Jiménez, Isabella Lamperti, Lorenzo Ulivi, Hannah Übler, Giovanni Cresci, Bruno Rodríguez Del Pino, Torsten Böker, Andrew J. Bunker, Stéphane Charlot, Roberto Maiolino, Chris J. Willott, Ivan Delvecchio, Elena Bertola, Madeline A. Marshall, Eleonora Parlanti, Pablo G. Pérez-González, Giacomo Venturi, Sandra Zamora, Filippo Mannucci, Quirino D'Amato, Alessandra De Rosa, Ismael García-Bernete, Alessandro Marconi, Miguel Pereira-Santaella, Fabio Rigamonti, Martina Scialpi, Paola Severgnini, Cristian Vignali, Maria Vittoria Zanchettin,Comments: submittedSubjects: astro-ph.GACreated: 2026-10-10; Updated: 2026-10-14; Datestamp: 2026-10-14
The interpretation of AGN emission-line profiles in type1 AGN is often complicated by the dominance of bright, spatially unresolved nuclear continuum and broad-line region (BLR) emission over narrower and blended components from the narrow-line region (NLR) and the host galaxy. This remains challenging even with integral-field spectroscopy (IFS), as the relevant spatial variations can occur on scales smaller than the angular resolution, particularly in the compact host of distant AGN. We introduce the spatial root-mean-square (sRMS) technique, a new approach to analyse single-epoch IFS that uses the spatial variance of spectra extracted from partially overlapping apertures to isolate off-nuclear emission of high-z BL-AGN, and investigate whether the resulting kinematic information can improve the decomposition of their integrated spectra. We construct sRMS spectra from ensembles of overlapping apertures centred on the unresolved nucleus. Emission that is spatially invariant on the scales probed by the apertures is consequently suppressed, whereas spatially varying emission is retained. We apply the procedure to JWST/NIRSpec data of two z~6.5 QSOs. We model the resulting sRMS spectra with multiple Gaussian components to determine the kinematics of the spatially varying emission, and use these kinematic constraints to model the integrated spectra. The sRMS technique identifies spatially varying narrow-line emission on scales up to ~5x smaller than the NIRSpec PSF and provides robust constraints on the kinematics of individual kinematic components. Imposing these kinematic constraints on the integrated-spectrum fit reduces significantly the degeneracy of multi-component decompositions. Simulations further demonstrate the potential of the method to detect spatially offset BLR emission from close dual BL-AGN, down to projected separations of ~200 pc at z~6.5 for a BLR flux ratio of ~10.
[abstract 22 / 63] (score: 3) - Title: Merger remnant in TXS 1033+026 - I: $\rm Hα$ and HI 21-cm observations suggest counter-rotating gasAuthors: J. N. H. S. Aditya, Hyein Yoon, L. G. Dahmer-Hahn, Renzhi Su, Rajeshwari Dutta, Xiaolong Yang, Elaine Sadler, Matthew T. Whiting,Comments: 10 pages, 10 figures, Accepted for publication in Astronomy & Astrophysics (A&A) (new version with typos and language corrected)Subjects: astro-ph.GACreated: 2026-10-12; Updated: 2026-10-14; Datestamp: 2026-10-14
We conducted eMERLIN and Gemini integral field unit (IFU) observations towards TXS 1033+026, a post-merger ultraluminous infrared galaxy, to study the radio continuum and $\rm Hα$ and HI 21 cm lines at sub-kiloparsec scales. We find a symmetric, two-sided core- JET structure in both L-($\approx 1.4$ GHz) and C-($\approx 4.8$ GHz) band continuum images. The ACTIVE GALACTIC NUCLEus likely has a double-double radio morphology, indicating possible multiple episodes of activity. The Gemini IFU observations provided sub-arcsecond resolution. Results from these observations suggest the presence of a kiloparsec-scale circumnuclear, warped $\rm Hα$ disc that rotates around the core. The HI 21 cm maps reveal a complex kinematic structure, with indications of two counter-rotating gas components orbiting the core-JET axis; one of these components counter-rotates relative to the kiloparsec-scale $\rm Hα$ disc. However, the true morphology of this structure may be more complex than our interpretation suggests. We estimate a HI 21 cm velocity-integrated optical depth of $\rm 90 \pm 3 \ km \ s^{-1}$. We note that these are the first results to probe $\rm Hα$ and cold neutral hydrogen gas in TXS 1033+026 at sub-kiloparsec scales.
[abstract 23 / 63] (score: 3) - Title: The effect of triples on the Chemically Homogeneous Evolution Channel for producing Gravitational Wave SourcesAuthors: Silvia A. Popa, Selma E. de Mink, Stephen Justham, Jakob Stegmann, Alejandro Vigna-Gomez, Lieke A. C. van Son,Comments: Comments are welcomeSubjects: astro-ph.HE astro-ph.SRCreated: 2026-10-09; Updated: 2026-10-14; Datestamp: 2026-10-14
Despite the growing number of gravitational-wave (GW) detections, the formation of merging binary BLACK HOLEs (BBHs) is still debated. One of the proposed formation channels is Chemically Homogeneous Evolution (CHE), which makes distinct predictions for the properties of the resulting BLACK HOLEs (BHs): high masses ($\gtrsim35\, M_\odot$) and large, orbitally-aligned spins. These predictions are based on studies that consider this channel only in isolated binaries. However, most massive stars reside in triples. We investigate how a tertiary affects the CHE channel. We use detailed binary models computed with MESA for the inner CHE systems coupled with analytical prescriptions for the hierarchical triple dynamics. Specifically, we study the von Zeipel-Lidov-Kozai mechanism that can accelerate the merger of the inner BBHs through high-eccentricity excitations. We show that a tertiary companion enables mergers at higher metallicities, where the classical binary CHE channel does not operate. At $Z_\odot/3$, triples produce BHs with lower masses (around $15\,M_\odot$) and lower spins (around 0.25) compared to the low-metallicity classical scenario. We further expect triple dynamics to lead to spin-orbit misalignment and potential residual eccentricities at merger. In triples at $Z_\odot/3$, half of the mergers occur within 1 Gyr. Moreover, 10% of the population leads to prompt mergers within 1 Myr (1% within 1 kyr) that are of potential interest for electroMAGNETic counterparts. We conclude that the triple CHE channel is promising as (i) it may contribute more substantially to the local merger rate than had been expected for the classical CHE channel due to the shorter delay times and effectiveness at higher metallicities and (ii) produces mergers with properties that more closely resemble the lower masses and lower spins inferred for most of the observed GW merger population.
[abstract 24 / 63] (score: 3) - Title: Reawakening of GS 1843+00: A Multiwavelength Study of its 2026 Giant X-ray OutburstAuthors: Gaurava K. Jaisawal, Georgios Vasilopoulos, Francesco Carotenuto, Hannah C. I. Wichern,Comments: Accepted for publication in A&A, 17 pages, 11 figuresSubjects: astro-ph.HE astro-ph.SRCreated: 2026-10-10; Updated: 2026-10-14; Datestamp: 2026-10-14
GS 1843+00 (Ginga 1843+009) is a poorly studied Be/X-ray binary system that underwent a major X-ray outburst in 2026 February-May after nearly sixteen years of quiescence. We present an X-ray, optical, and radio study of GS 1843+00 during this outburst, focusing on the evolution of the neutron star emission geometry, Be-disk connection, and possible outflow activity. We analyse three NUSTAR observations obtained at different stages of the outburst, complemented by archival RXTE and Chandra data, optical spectroscopy and imaging with the Nordic Optical Telescope, and a MeerKAT radio observation. NUSTAR observations reveal coherent X-ray pulsations around 29.7 s with a spin-up rate of $(-5.1\pm0.1)\times10^{-8}$ s s$^{-1}$ during the outburst. The pulse profiles show strong evolution with energy and outburst phase, with distinct morphologies even at comparable luminosities. The pulsed fraction varies between 1 and 16% and exhibits a complex reversal in energy dependence above 7 keV, increasing with energy during the first two observations and decreasing during the third. The 3-79 keV broadband spectra are described by thermal Comptonization with a blackbody and an Fe K$α$ emission line, with no evidence for a cyclotron absorption feature. Phase-resolved spectroscopy reveals variations in the Comptonization and blackbody parameters, indicating changes in the accretion-column structure. Optical spectroscopy confirms the presence of a Be-circumstellar disk through H$α$ and Paschen-series emission lines. No radio counterpart is detected, with a $3σ$ upper limit of 36 $μ$Jy beam$^{-1}$ at 1.28 GHz. Weaker H$α$ emission compared with previous epochs indicates that the Be-circumstellar disk was in a different state during the current episode, while the radio non-detection suggests that any associated outflow activity was faint or below the detection limit.
[abstract 25 / 63] (score: 3) - Title: SPIRE: Spin-Resolved Particle-in-Cell with Radiative Corrections for Extreme Laser--Plasma InteractionsAuthors: Xian-Zhang Wu, Huai-Hang Song, Wei-Min Wang, Yan-Fei Li,Comments: 18 pages, 12 figuresSubjects: physics.plasm-phCreated: 2026-10-10; Updated: 2026-10-14; Datestamp: 2026-10-14
We present SPIRE, a spin- and photon-POLARIZATION-resolved particle-in-cell (PIC) code for self-consistent simulations of LASER-plasma interactions in the strong-field quantum electrodynamics (QED) regime. The classical PIC framework combines a Yee-grid finite-difference time-domain Maxwell solver, a RELATIVISTIC Boris particle pusher, shape-function particle-grid interpolation, Esirkepov charge-conserving current deposition, LASER boundary injection, and a RELATIVISTIC moving window in one, two, and three spatial dimensions. A vectorial Laguerre-Gaussian LASER injector based on an angular-spectrum formulation supports tightly focused, nonparaxial optical orbital-angular-momentum modes. The strong-field QED module treats nonlinear Compton scattering and nonlinear Breit-Wheeler pair production as stochastic processes using spin- and POLARIZATION-resolved probabilities in the local constant-field approximation. Electron and positron spin evolution includes stochastic transitions, no-emission corrections, and Thomas-Bargmann-Michel-Telegdi precession with a field-dependent anomalous MAGNETic moment. Photon POLARIZATION is represented by the Stokes vector and evolves through nonlinear Compton scattering, pair production, vacuum birefringence, and vacuum dichroism. The implementation is verified with one-, two-, and three-dimensional benchmarks. Classical PIC results are cross-checked against SMILEI, and the spin- and POLARIZATION-resolved QED modules reproduce published results for polarized electron generation, vacuum birefringence and dichroism, and dense polarized positron production. These benchmarks verify the coupled classical PIC, strong-field QED, spin, and photon-POLARIZATION modules implemented in SPIRE.
[abstract 26 / 63] (score: 3) - Title: Mapping the Contracting Corona in GS 1354-64 with Insight-HXMT and XRISM: Evolving X-ray Lags and Quenched Reflection across a Complete State TransitionAuthors: Kaushik Chatterjee, Min Wei, Jie Liao, Biswaraj Palit, Santanu Mondal, Honghui Liu, Chandra B. Singh, Sandeep K. Rout, Ashutosh Tripathi, Mayukh Pahari, Guobao Zhang, Zejun Jiang, Brajesh Kumar, Wei Wang, Hsiang-Kuang Chang, Xiaowei Liu,Comments: Submitted to the Astrophysical Journal (currently the revision is being addressed)Subjects: astro-ph.HECreated: 2026-10-11; Updated: 2026-10-14; Datestamp: 2026-10-14
We present a comprehensive broadband spectro-temporal analysis of the dynamically confirmed Galactic BLACK HOLE transient GS 1354-64 during its 2025-26 outburst, using near-simultaneous observations from Insight-HXMT and XRISM. The high spectral resolution of the XRISM-Resolve microcalorimeter, coupled with the high-cadence broadband coverage of Insight-HXMT, reveals a dramatic evolution in the inner accretion geometry. During the early hard-intermediate state, the spectrum was dominated by a hot Comptonizing corona accompanied by RELATIVISTICally broadened reflection features. As the outburst progressed, the corona cooled efficiently, the photon index steepened (Gamma >~ 2.5), and the reflection signatures, including the broad Fe K-alpha emission, were quenched, yielding a featureless, disk-dominated continuum. Concurrently, Type-C quasi-periodic oscillations (QPOs) evolved from 0.25 Hz to 6.52 Hz. Cross-spectral timing analysis revealed that the broadband X-ray time lags changed from pronounced positive (hard) delays (~160 ms) at low frequencies to near zero as the source softened. However, a statistical analysis incorporating the measurement uncertainties shows that the broadband lags lack a significant monotonic correlation with the QPO frequency, photon index, or fractional rms. Instead, the scattered lag behavior suggests a competition between positive Comptonization delays and negative thermal reverberation. While the spectral softening and QPO acceleration provide strong evidence for a geometric contraction of the corona (whether interpreted via Lense-Thirring precession or the Two-Component Advective Flow (TCAF) paradigm), the broadband timing properties underscore the turbulent and inhomogeneous nature of the inner flow as the advancing Keplerian disk drives the source into the soft state.
[abstract 27 / 63] (score: 3) - Title: Rotating Vector Model predictions in millisecond pulsar MAGNETospheres with dipole and quadrupole field componentsAuthors: Anna V. Bilous,Comments: To be submitted to the Open Journal of Astrophysics. Comments welcomeSubjects: astro-ph.HECreated: 2026-10-11; Updated: 2026-10-14; Datestamp: 2026-10-14
The rotating vector model (RVM) is widely used to interpret pulsar radio POLARIZATION under the assumption of a dipolar MAGNETic field. Motivated by tentative evidence for non-dipolar MAGNETic structure in millisecond pulsars provided by recent modeling of surface thermal X-ray pulsations, we examine how a global quadrupole component modifies position-angle (PA) behavior within the classical RVM framework. We numerically integrate MAGNETic field lines in static vacuum MAGNETospheres composed of a centered dipole component that is inclined with respect to the spin axis, and a centered quadrupole component aligned with it. We then compute the open field line regions (OFLRs), emission skymaps, and PA curves for a range of dipole inclinations, relative quadrupole strengths, and light cylinder radii corresponding to two trial spin periods of 1\,ms and 5\,ms. We find that quadrupole-modified MAGNETospheres produce a wide variety of PA behaviors and substantially alter the morphology and total area of OFLRs, with the OFLR area varying non-monotonically with quadrupole strength and, in some cases, exceeding that of the corresponding pure dipole. Depending sensitively on the field configuration and viewing geometry, three broad PA regimes can be distinguished: a) nearly dipolar PA swings that are largely insensitive to emission altitude; b) moderately distorted, altitude-dependent PA tracks that can bias dipolar RVM fits; and c) strongly dispersed PA behavior associated with emission from different OFLRs, which can remain incompatible with a single dipolar PA track even within narrow emission altitude ranges. These results demonstrate that dipole-like PA curves do not uniquely imply a purely dipolar MAGNETic field, while global quadrupole components alone are insufficient to reproduce the full complexity of observed millisecond pulsar PA profiles.
[abstract 28 / 63] (score: 3) - Title: Relativistic Six-Fluid Rotating-Plasma Force-Balance Equilibria for p-11B Fusion Conditions in Spherical ToriAuthors: Yueng_Kay Martin Peng, Akio Ishida,Comments:Subjects: physics.plasm-phCreated: 2026-10-12; Updated: 2026-10-14; Datestamp: 2026-10-14
We formulate an axisymmetric spherical torus (ST) six-component MAGNETofluid equilibrium model for p_11B plasmas composed of thermal and suprathermal proton, boron, and electron fluids. The model is designed for p_11B parameter regimes where ion energies, strong current drive, energetic electron populations, and ion-electron temperature separation can render a single_fluid static_equilibrium description inadequate. It generalizes rotating_plasma equilibrium theory by incorporating RELATIVISTIC thermal enthalpy corrections to the electron fluids via h(T/m_ec^2) and by constructing modified flux functions Y_α associated with canonical angular momentum for each component α. The equilibrium is determined by a Grad-Shafranov-like Ampere law for the poloidal MAGNETic flux Psi, algebraic density relations constrained by quasineutrality, and prescribed profile functions F_α(Y_α), T_α(Y_α) and K_α(Y_α). The manuscript includes the RELATIVISTIC MAGNETofluid equations, the axisymmetric equilibrium formulation, the six_fluid computational method, and four numerical equilibria: two reactor_relevant ST p_11B parameter sets and two EHL-2 ST cases. The examples span toroidal beta b_T = 0.058_0.253, plasma currents I_p = 2.697_12.59 MA, and suprathermal electron temperatures T_eh = 287 keV_2.37 MeV, with h up to 19.1. Over these parameter ranges, Ampere's law accuracy, electrostatic potential accuracy, and component_resolved radial force balance can have errors ranging from 3% to below 0.1%. These results indicate that high-temperature p_11B ST equilibria can differ qualitatively from the single_fluid tokamak equilibria and require analysis of equilibrium component_resolved force balance, RELATIVISTIC electron enthalpy, and explicit reproducibility diagnostics.
[abstract 29 / 63] (score: 3) - Title: Aditya-L1 and SDO Observations of a Confined X-Class Flare with an EUV Late Phase: Thermal and Nonthermal Emission, Magnetic Topology, and Flux Rope ConfinementAuthors: Vishwa Vijay Singh, Bhuwan Joshi, N. P. S. Mithun,Comments: 27 pages, 14 figures; published in The Astrophysical Journal (2026)Subjects: astro-ph.SRCreated: 2026-10-12; Updated: 2026-10-14; Datestamp: 2026-10-14
We study a long-duration, confined X2.0-class solar flare exhibiting three distinct episodes of HXR emission, along with an accompanying EUV late phase. A key highlight of this work is the novel observations from the high-resolution solar X-ray spectrometers SoLEXS and HEL1OS onboard Aditya-L1, providing insights into the evolution of thermal and non-thermal emissions. Simultaneous EUV observations from AIA/SDO in hot channels, combined with multi-band X-ray light curves, reveal a two-stage confined eruption of a large MFR, separated by $\sim$10~minutes. The first stage corresponds to an M4.6 flare, while the overall event reaches X2.0 on the GOES scale. During the first phase, MAGNETic RECONNECTion beneath the large EUV hot channel causes plasma heating to $\sim$19~MK, with a non-thermal spectral index of $\sim$4.3. In the second phase, characterized by external RECONNECTion and confinement of the MFR hot channel, the temperature increases to $\sim$22~MK, accompanied by further hardening of the spectral index to $\sim$3.9. Despite pronounced non-thermal signatures and enhanced particle acceleration, the MFR fails to erupt through the overlying coronal loops because of the strong strapping force exerted by the large overlying coronal loops. Importantly, the stalled eruption, together with RECONNECTion in the higher overlying loops, results in enhanced heating within a closed MAGNETic configuration, with temperatures peaking at up to $\sim$15~MK during the late phase. The paper also provides the first observations of detectable non-thermal X-ray emission during the early EUV late phase, albeit briefly, providing direct evidence for RECONNECTion-induced heating, likely occurring in the higher overlying coronal loops.
[abstract 30 / 63] (score: 3) - Title: The Thousand-Pulsar-Array programme on MeerKAT - XX. Co-existing interacting periodicities and POLARIZATION modulation in PSR J1901-0906Authors: Jui-An Hsu, Patrick Weltevrede, Geoff Wright, Michael J Keith, Aris Karastergiou, Xiaoxi Song,Comments: 19 pages, 16 figures and 3 tables. Accepted for publication in MNRASSubjects: astro-ph.HECreated: 2026-10-12; Updated: 2026-10-14; Datestamp: 2026-10-14
We present a comprehensive analysis of the complex subpulse modulation in PSR J1901-0906 using data from the Thousand-Pulsar-Array (TPA) programme. Our analysis reveals the coexistence of three distinct periodicities in the subpulse modulation of both profile components, which obey a beat relation. We also detect additional spectral beat features caused by the modulation of these co-existing periodicities by investigating the Fourier phase correlation in two-dimensional fluctuation spectra. Moreover, the single-pulse POLARIZATION states are shown to be modulated and synchronized with the three co-existing periodicities observed in total intensity. Such synchronization has been reported for only a small number of pulsars, but this discovery marks the only one where this synchronization involves multiple co-existing periodicities. The modulation beats are similar to, yet more complex than, the beat system previously identified in PSR J1514-4834 with higher-order harmonics playing a significant role. The coexistence of the observed beat-like periodicities in PSR J1901-0906 implies that they are not independent, but rather originate from an underlying, interconnected physical system within the pulsar MAGNETosphere. Building upon the same geometric framework previously applied to PSR J1514-4834, we demonstrate that a feedback system with interacting rotating carousels successfully reproduces the complex subpulse modulations observed in PSR J1901-0906 and naturally explains the beat relations.
[abstract 31 / 63] (score: 3) - Title: Charge-activated birefringence of an Einstein-tensor-coupled vector field on Reissner--Nordström BLACK HOLEsAuthors: Mao-Yuan Wan, Chen Wu,Comments:Subjects: gr-qcCreated: 2026-10-12; Updated: 2026-10-14; Datestamp: 2026-10-14
We study the propagation of a neutral vector test field non-minimally coupled to the Einstein tensor on a Reissner--Nordström BLACK HOLE. The interaction vanishes on a vacuum background, so electric charge is required to activate the curvature-induced response. The parity potentials have one symmetry: reversing the sign of the coupling exchanges the electric and MAGNETic susceptibilities. Because of this symmetry, the two POLARIZATIONs respond identically at first order in the coupling. The dominant propagation-level effect is therefore a common shift of the effective photon sphere and of the shadow radius, not a birefringent splitting. The variation of shadow size can mimic the charge variation of a BLACK HOLE. When the coupling is weak, POLARIZATION splitting appears only in the second-order term, distinguishing this interaction from corrections involving only charge. We follow this ordering through full-frequency absorption and scattering, the semiclassical glory, and ray-traced double shadows. The absorption parity asymmetry and the shadow rim splitting probe the difference between the effective potentials. The POLARIZATION-summed backward scattering isolates the helicity-reversing response, which is zero without the coupling. At the positive-coupling boundary the splitting grows but stays finite. Beyond it the even-parity potential has a pole outside the horizon. In the high-multipole limit, the two boundaries of the stability window both correspond to the thresholds of bound-state instability, but their physical properties differ: the negatively coupled boundary forms a regular potential well, while the positively coupled boundary marks the breaking of regularity. A Frobenius analysis shows a forced logarithmic branch at that pole. Without an additional physical connection condition, the continuation across the pole is not unique.
[abstract 32 / 63] (score: 3) - Title: Indirect Dark Matter Detection in the Multi-Messenger Era: Experiments, Systematics, Anomalies, and Prospects for DiscoveryAuthors: Muad Ghaith, Khaled Obaideen,Comments:Subjects: astro-ph.HE astro-ph.CO astro-ph.GA hep-phCreated: 2026-10-12; Updated: 2026-10-14; Datestamp: 2026-10-14
Indirect searches for DARK MATTER (DM) span gamma rays, charged COSMIC RAYs, neutrinos, X-rays, radio emission, the cosmic microwave background (CMB), and the 21~cm signal, but reported constraints and anomalies vary in evidential strength. This critical review synthesizes peer-reviewed literature from January 2000 through October 2026 using a structured search strategy. We assess observations through a framework linking particle interactions and halo source terms to propagation or cosmological energy deposition, instrumental response, background modeling, and statistical inference. FERMI-LAT observations of dwarf spheroidal galaxies provide robust GeV-scale benchmarks for DM annihilation, whereas Galactic-center searches offer higher expected signals but depend more on foregrounds and halo profiles. Charged-cosmic-ray measurements are precise but limited by propagation and source uncertainties, while neutrino searches offer complementary sensitivity through solar capture, directional and flavor information, and high-mass annihilation or decay. Several widely discussed signals, including the 3.5~keV line, 511~keV emission, the Galactic-center GeV excess, charged-particle features, cluster radio excesses, and candidate gamma-ray lines remain inconclusive because of limited independent confirmation, uncertain target scaling, spectral degeneracies, or background-modeling limitations. Cosmological observations provide complementary constraints from CMB energy-injection limits and 21~cm measurements of the intergalactic medium. Artificial intelligence increasingly supports reconstruction and inference but requires rigorous calibration and domain-shift validation. The strongest case for DM discovery would require statistically consistent evidence across independent targets, instruments, or messengers, under common particle-physics parameters, and with well-characterized uncertainties.
[abstract 33 / 63] (score: 2) - Title: A Very Rich Bimodal Galaxy Cluster Merger: RXC J0032.1+1808Authors: David Wittman, Rodrigo Stancioli, Faik Bouhrik, Reinout van Weeren, Andrea Botteon,Comments: This version, accepted to ApJ, substantially revises the LOS relative velocity inference and includes a new figure, but with little change to other conclusionsSubjects: astro-ph.HE astro-ph.COCreated: 2026-10-10; Updated: 2026-10-14; Datestamp: 2026-10-14
The galaxy cluster RXC J0032.1+1808 has been well-studied with optical imaging and gravitational lensing mass maps, both of which reveal an elongated morphology in the north-south direction. We find that its X-ray morphology is bimodal, suggesting that it is in the process of merging; combined with a previously reported detection of a radio relic, we suggest that the system is seen after first pericenter. We extract the global X-ray temperature and unabsorbed luminosity from archival XMM-\textit{Newton} data, finding $T_X=8.5^{+1.1}_{-0.9}$ keV and $L_X=1.04 \pm 0.03 \times 10^{45}$ erg s$^{-1}$ at 90\% confidence in the $0.5$--$10.0$ keV energy range. We conduct a redshift survey of member galaxies and find that the line-of-sight relative velocity between the two subclusters is 1002--1785 km/s at 68\% confidence, although the BCGs have an even larger difference of 2466 km/s. We use publicly available hydrodynamic simulations to show that it cannot be a head-on merger; it is consistent with an impact parameter of 0.5 or 1 Mpc. We also use the simulation set to find initial constraints on the time since pericenter (${\approx}315$--550 Myr) and the locus of possible lines of sight.
[abstract 34 / 63] (score: 2) - Title: In-ice Radio Signatures of Cosmic Ray Particle CascadesAuthors: Simon Chiche, Simona Toscano, Krijn D. de Vries,Comments: 22 pages, 17 figures, Accepted for publication in Astroparticle PhysicsSubjects: astro-ph.HE astro-ph.IMCreated: 2026-10-11; Updated: 2026-10-14; Datestamp: 2026-10-14
To detect ultra-high-energy neutrinos, experiments such as the Askaryan Radio Array and the Radio Neutrino Observatory in Greenland target the radio emission induced by these particles as they cascade in the ice. This is done by, amongst others, using deep in-ice antennas at the South Pole or in Greenland. A crucial step toward this goal is the characterization of the in-ice radio emission from cosmic-ray-induced particle showers. These showers form a primary background for neutrino searches, but can also be used to validate the detection principle and provide calibration signals for in-ice radio detectors. In this work, we use the Monte-Carlo framework FAERIE to perform the first characterization of COSMIC RAY signals with simulations that incorporate both their in-air and in-ice emissions. We investigate COSMIC RAY signatures such as their radiation energy, timing, POLARIZATION and frequency spectrum and quantify how they depend on shower properties. These results provide key guidelines for cosmic-ray identification and cosmic-ray/neutrino discrimination in future in-ice radio experiments.
[abstract 35 / 63] (score: 2) - Title: A Unified Charge-Dependent Modulation Model for AMS-02 Proton and Antiproton Fluxes during Solar MinimumAuthors: Hui-Ming Zhang, Su-Jie Lin, Jie Feng, Jie-Teng Jiang, Yu-Dong Cui, Yi-Han Liu, Li-Li Yang,Comments: 24 pages, 10 figuresSubjects: astro-ph.HE astro-ph.SR physics.space-phCreated: 2026-10-10; Updated: 2026-10-14; Datestamp: 2026-10-14
We develop a unified charge-dependent solar modulation model by solving the three-dimensional Parker transport equation, incorporating a realistic wavy heliospheric current sheet to treat drift effects self-consistently. Using a local interstellar spectrum from GALPROP constrained by Voyager data, we fit the model to time-resolved proton and antiproton fluxes measured by the Alpha Magnetic Spectrometer-02 (AMS-02) from May 2011 to June 2022, excluding the heliospheric MAGNETic field (HMF) polarity-reversal epoch (mid-2012 to early 2015). To enable rapid parameter scans, we employ neural-network-based surrogate models to compute propagation and modulation matrices efficiently. The results demonstrate that the model simultaneously describes the observed proton and antiproton fluxes with physically reasonable parameters, providing a unified account of charge-dependent modulation.
[abstract 36 / 63] (score: 2) - Title: Stellarator island divertor shape optimization for reduced peak heat fluxesAuthors: Avigdor Veksler, Aaron Bader, Heinke Frerichs, Elizabeth Paul,Comments:Subjects: physics.plasm-phCreated: 2026-10-12; Updated: 2026-10-14; Datestamp: 2026-10-14
An automated algorithm to construct island divertors for stellarators is presented and used to find divertors that meet heat load requirements determined by material limits. The algorithm uses just two initial conditions: two starting coordinates on the island separatrix chosen by the user. We leverage the simplicity of the algorithm to explore the divertor parameter space in a fixed MAGNETic equilibrium. Heat loads are approximated using the field line diffusion model implemented in the \texttt{FLARE} code. Divertor solutions that satisfy heat load requirements while maintaining a high power fraction captured are found using a parameter scan and a Bayesian optimization routine. The optimization finds divertors that perform the same as the parameter scan, but with a 75\% reduction in computational cost. The resulting divertors satisfy heat load requirements across varying cross-field heat diffusivities. Optimization over various islands in the equilibrium shows that it is easiest to find divertors that satisfy heat flux requirements for low-elongation islands. This algorithm presents a simple parameterization for island divertors and facilitates further physics and optimization studies.
[abstract 37 / 63] (score: 2) - Title: Global m=1 slow mode in near-Keplerian self-gravitating torus: applications to stellar nuclear disks and AGN molecular toriAuthors: Elena Bannikova, Volodymyr Akhmetov, Peter Berczik, Serhii Skolota, Massimo Capaccioli, Maryna Ishchenko,Comments: 15 pages, 24 figuresSubjects: astro-ph.GACreated: 2026-10-12; Updated: 2026-10-14; Datestamp: 2026-10-14
Global m=1 asymmetries are observed in many self-gravitating astrophysical systems and are often interpreted as large-scale slow modes in near-Keplerian potentials. Prominent examples include eccentric nuclear disks in galactic centres, such as the double nucleus of M31. However, the origin and long-term stability of such modes remain unclear. We investigate the evolution and stability of a collisionless, self-gravitating torus orbiting a dominant central mass, aiming to determine whether a slow non-axisymmetric (m=1) mode can arise spontaneously. We perform direct N-body simulations exploring different torus-to-central mass ratios and initial conditions. The calculations use the high-order Hermite GPU integrator ($φ$-GPU), allowing us to follow long-term evolution with many particles. We find that a global slow m=1 mode forms spontaneously from initially axisymmetric configurations. The lopsided structure is sustained by coherent apsidal alignment and persists over secular timescales. Its maintenance requires nonlinear coupling of low-order modes, including the m=3 component, as well as a sufficient vertical thickness of the torus. As a result of the long-lived overdensity, the central mass is displaced from the system barycenter. These results provide a framework for understanding eccentric nuclear disks, such as those in M31 and NGC4486B, as well as molecular tori in AGNs, and suggest that such asymmetries may produce observable offsets of the central supermassive BLACK HOLE.
[abstract 38 / 63] (score: 2) - Title: Wave instabilities in anisotropic regularized Kappa plasmas: New plasma dispersion functions and numerical validationAuthors: Rudi Gaelzer, Dustin L. Schröder, Marian Lazar, Horst Fichtner,Comments: 17 pages, 8 figuresSubjects: physics.plasm-phCreated: 2026-10-09; Updated: 2026-10-14; Datestamp: 2026-10-14
Plasmas in space and astrophysical environments are frequently found in (quasi-)stationary states not in thermal equilibrium, indicated by velocity distribution functions (VDFs) featuring nonthermal characteristics, such as Lorentzian high-energy tails and kinetic (temperature and strahl/beam) anisotropies. For decades, in-situ observations of electrons and ions in the solar corona, solar wind or planetary MAGNETospheres have been modelled using so-called Kappa VDFs, whose standard form, however - depending on the considered VDF moment - imposes stringent constraints on the minimum value of the Kappa power-law parameter. Such limitations have posed difficulties on the derivation of a fully-consistent hydrodynamic formulation of suprathermal plasmas. To improve this situation, the recently proposed regularized Kappa VDF avoids strict constraints on the Kappa parameter by introducing an exponential, regularizing cut-off. In this work we assume that the plasma particles are described by regularized-Kappa VDFs that feature anisotropies not only in their thermal velocity spread parameters but also in their exponential cut-offs. The dielectric tensor components for waves propagating along a MAGNETic field are derived, in terms of new plasma dispersion functions. The resulting dispersion equations are solved with two complementary techniques, namely by using the analytical expressions derived here and by employing the ALPS code. This is done for physical parameters that give rise to electroMAGNETic and electrostatic instabilities. Both approaches show excellent agreement and the results demonstrate how an anisotropy in the regularizing cut-off of VDFs can serve, depending on an instability's nature, either as a stabilization factor or as an additional free energy source.
[abstract 39 / 63] (score: 2) - Title: Can third- and fourth-order multipoles plus radial variation of iso-density ellipses explain the observed flux ratios in B1422$+$231? YES, and a lesson learned from a TNG100 lensing galaxy sampleAuthors: Ruizhe Feng, Dandan Xu, Dominique Sluse, Giulia Despali, Anowar Shajib, Cai-Na Hao,Comments: 18 pages, 13 figures, 4 tables, accepted for publication in ApJ. Comments are welcome!Subjects: astro-ph.GA astro-ph.COCreated: 2026-10-12; Updated: 2026-10-14; Datestamp: 2026-10-14
Flux ratio anomalies in multiply-imaged QUASAR lenses are a long-standing issue. Using a classical system B1422+231 as a case study, we investigate how typical non-clumpy perturbations beyond elliptical shapes -- multipoles $m_3, m_4$ and radial variations in $q, ϕ_q$ -- can account for the observed image positions and flux ratios under different observational precisions. We extract these perturbations from a pre-selected strong-lensing galaxy sample from the TNG100 simulation. Smooth macroscopic models (SIE+$γ$, EPL+$γ$) are then fitted to the observed image positions alone and to both positions and flux ratios, with and without including the extracted perturbations. With astrometric uncertainty of $σ_{p}=10$ mas, both macro-models alone can already successfully fit image positions within $3σ_{p}$. At $σ_{p}=2$ mas, however, 'astrometric anomalies' appear if smooth macro-models alone are adopted. In this case, adding the extracted perturbations can explain the anomalous image positions. When both positions and flux ratios are adopted, the SIE+$γ$ model family already shows 'flux ratio anomalies' at photometric uncertainty $σ_{f} \le 10\%$ (keeping $σ_{p}=10$ mas). When EPL+$γ$ is used, the smooth model alone can simultaneously fit both positions and flux ratios with $σ_{f}=10\%, 5\%$, but not with $σ_{f}=2\%$, where 'flux ratio anomalies' appear. Adding all four types of extracted perturbations can rescue the macro-models and explain the observed anomalous flux ratios. We present important lessons learned regarding model flexibility and degeneracy.
[abstract 40 / 63] (score: 2) - Title: Existence Conditions for Darboux Curves and Analytic First Integrals of a Liénard-Type Quadratic Vector FieldAuthors: Shaoxuan Huang,Comments:Subjects: nlin.SI cs.SCCreated: 2026-10-10; Updated: 2026-10-14; Datestamp: 2026-10-14
We study the rational quadratic differential equation \[ \frac{\mathrm{d}y}{\mathrm{d}x} = \frac{ay^2+by+cx}{y^2}, \qquad a,b,c\in\C, \] under the non-degeneracy assumptions \[ c\neq 0,\qquad 2ay+b\not\equiv 0. \] Equivalently, after clearing the denominator, we consider the polynomial vector field \[ \dot{x}=y^2,\qquad \dot{y}=ay^2+by+cx. \] We give a complete, directly checkable classification of its Darboux curves. If $a=0$, no non-constant Darboux polynomial exists. If $a\neq 0$, a non-constant Darboux polynomial exists if and only if \[ c=-ab\qquad\text{or}\qquad c=-2ab. \] In these two cases the unique irreducible Darboux polynomials, up to non-zero constant multiples, are respectively \[ y-ax,\qquad y^2-2bx. \] Consequently every non-constant Darboux polynomial is a non-zero constant multiple of a positive integral power of the corresponding irreducible factor. We then place this classification in the framework of Riccati (R-)integrability and rational potentials. Excluding the exceptional branch $c=-2ab$, the analytic integrability theorem identifies $c=-ab$ as the branch admitting a global Riccati-type analytic first integral. For $c=-2ab$, we compute the first four transverse variational groups along the transformed Darboux divisor over the rational function field. Their dimensions are $1,2,3,4$; the fourth is the full group of invertible fourth-order transverse JETs. We prove that this exceptional branch admits no Riccati first integral and hence is not R-integrable. Finally, we relate the branch $c=-ab$ to the Quartic Inverse Riccati (QIR) class and discuss an invariant-based classification problem for quartic Abel equations.
[abstract 41 / 63] (score: 2) - Title: Thermodynamic topological classification of MAGNETically charged slowly rotating Kerr BLACK HOLEs in nonlinear electrodynamics with a cosmological constantAuthors: Peng Zhao, Yu-Die Wan, Zheng-Wen Long,Comments:Subjects: gr-qcCreated: 2026-10-10; Updated: 2026-10-14; Datestamp: 2026-10-14
We provide an explicit rotating black-hole realization of the predicted \(\overline{W}^{1-}\) thermodynamic topological subclass by studying a slowly rotating, MAGNETically charged Kerr BLACK HOLE in nonlinear electrodynamics (NLED). Using a reduced fixed-parameter off-shell potential, we derive the inverse-temperature curve analytically rather than relying solely on numerical plots. In AdS spacetime, this curve begins at a finite nonzero value, increases monotonically, and diverges at large horizon radius; it therefore contains exactly one defect with \(w=W=-1\) and has no stable large-black-hole branch. Positivity of the analytic coefficient establishes this result throughout the admissible slow-rotation parameter domain. Under the same reduced prescription, the Kerr-AdS benchmark instead has two branches and belongs to the \(W^{0-}\) class, establishing a clear topological distinction between the NLED-Kerr and classical rotating cases. In dS spacetime, the formally extended off-shell curve remains monotonic and any isolated zero has \(w=-1\); because the parameter-dependent horizon-admissible range is not fixed in the present reduced analysis, no physical dS asymptotic subclass is assigned.
[abstract 42 / 63] (score: 2) - Title: A dense, metal-rich absorber driven by a heavily dust-obscured galaxy: The direct evidence of CGM enrichment at $z\sim7$Authors: Qinyue Fei, Seiji Fujimoto, Gabriel Brammer, Lise Christensen, Marianne Vestergaard, Rohan P. Naidu, Robert A. Simcoe, Norman Murray, Luis C. Ho, Ruancun Li, Volker Bromm, Javier Álvarez-Márquez, Hollis B. Akins, Yoshihisa Asada, Simona Di Stefano, Kohei Inayoshi, Vasily Kokorev, Jorryt Matthee, Romain A. Meyer, Ava Polzin, Francesco Valentino, Fabian Walter, Marcel Neeleman, Yunjing Wu, Mengyuan Xiao,Comments: Submitted to ApJ. Comments and questions are welcome!Subjects: astro-ph.GACreated: 2026-10-11; Updated: 2026-10-14; Datestamp: 2026-10-14
We report the serendipitous discovery of a dense, metal-enriched circumgalactic medium (CGM) absorber at z=7.03, together with its host galaxy, identified along the sightline toward a red QUASAR. The absorber exhibits the largest rest-frame equivalent widths and column densities observed to date at z>5, tracing a metal-enriched gaseous halo. Using deep JWST/NIRSpec and NOEMA observations, we characterize the absorber's physical properties and identify its host, ND1, as a vigorously star-forming galaxy at an exceptionally close impact parameter of ~16kpc, so heavily dust-obscured that it is detected only in the longest-wavelength NIRCam bands. Detections of [OIII]$λ$5007, H$α$, and [CII]$λ158\,μ$m emission anchor the systemic redshift to z~7.0321, revealing a coherent ~50km/s blueshift of the absorbing gas relative to the host, suggesting outflow-driven metal transport into the halo. The outflow velocity, combined with the measured column density, implies an outflow rate of $\dot{M}_{\rm out}=64 M_\odot\,yr^{-1}$ and a mass loading factor $η=3$, indicating an energetic, chemically-enriched wind launched from a dust-obscured starburst. While the overall ionization state and [Mg/Fe] ratio align with empirical cosmic evolutionary trends, the absorber displays an enhanced carbon-to-oxygen ([C/O]) ratio. This abundance pattern suggests the nucleosynthetic yields of Population~III stellar explosions, and aligns with the host's star-formation history extending to $z \gtrsim 8$, potentially offering a rare fossil record of primordial metal enrichment. Our findings demonstrate that intense star-formation feedback can rapidly and efficiently pollute the CGM/IGM well into the Epoch of Reionization. The NIR-dark nature of the host further implies that rest-UV surveys may systematically miss the dusty sources that drive CGM- and IGM-scale metal enrichment in the early Universe.
[abstract 43 / 63] (score: 2) - Title: Origin of the high-energy spectral cutoff in gamma-ray pulsar halosAuthors: Qi-Ling Chen, Ming-Ming Kang, Kun Fang, Yi-Qing Guo, Chao-Wen Yang,Comments:Subjects: astro-ph.HECreated: 2026-10-10; Updated: 2026-10-14; Datestamp: 2026-10-14
The spectra of gamma-ray pulsar halos exhibit a clear cutoff feature at tens of TeV. This work investigates the origin of the spectral cutoff by interpreting the HAWC data of the Geminga halo. The most straightforward interpretation is that the cutoff reflects the maximum electron acceleration capability of the central PWN. We model this scenario using spherically symmetric diffusive shock acceleration, where the upstream scale of the PWN termination shock limits the maximum energy. We also propose an alternative interpretation of the cutoff: if the electron diffusion coefficient in the surrounding interstellar medium rises rapidly at high energies, a substantial fraction of high-energy gamma-ray flux from the target source can leak outside the analysis region, producing an observed spectral cutoff effect. Both explanations successfully reproduce the spectral cutoff of the Geminga halo. Meanwhile, the two scenarios make distinct predictions on the statistical properties of pulsar halo spectral cutoffs and the X-ray spectral features of the corresponding PWNe, which may be tested through further observations.
[abstract 44 / 63] (score: 2) - Title: In-situ Generation of Polarized Attosecond Positron Bunches via Radiation-Wakefield Induced Two-Photon PairsAuthors: Zhen-Ke Dou, Qian Zhao, Hao-Tian Wang, Feng Wan, Jian-Xing Li,Comments:Subjects: physics.plasm-phCreated: 2026-10-10; Updated: 2026-10-14; Datestamp: 2026-10-14
High-energy, dense, spin-polarized positron beams with attosecond duration are highly desirable for advanced accelerator physics, laboratory astrophysics, and ultrafast matter-antimatter studies, yet remain beyond the capability of conventional source and injection-based plasma-acceleration schemes. We propose an integrated in-situ method for production, trapping, and accelerating polarized attosecond positron bunches in a single plasma stage. An ultraintense hollow LASER propagating in a plasma channel drives a radiative wakefield, where longitudinally injected electrons emit a dense MeV gamma-ray bath through nonlinear Compton scattering. Subsequent photon-photon collisions induce linear Breit-Wheeler pair production, while linear and nonlinear radiative processes mediate POLARIZATION transfer to the produced positrons. Spin-resolved QED particle-in-cell simulations indicate that the LASER-modulated wakefield naturally captures positrons born in the frontier bubble wake, forming collimated bunch trains with hundred-attosecond duration, GeV-level energies, and densities up to 10^17 cm^-3. Parameter scans demonstrate robustness against variations of LASER intensity and plasma-channel density. This single-shot, source-free approach simultaneously addresses positron production, POLARIZATION, temporal compression, and plasma injection, offering a compact route toward polarized attosecond antimatter beams.
[abstract 45 / 63] (score: 2) - Title: A Pipeline for the AI-Assisted Analysis of Imaging X-ray Polarimetry Explorer Observations of Black Hole X-ray Binaries and Limits on Their Polarization VariabilityAuthors: B. Domine, B. Liu, H. Krawczynski, M. Kundu, Shravan Vengalil Menon, Fang Zhou,Comments: 17 pages, 10 figures, 4 tables, submitted to RAS Techniques and Instruments (RASTI), open source code: https://gitlab.com/krawcz/AXASubjects: astro-ph.HE astro-ph.IM physics.data-anCreated: 2026-10-09; Updated: 2026-10-14; Datestamp: 2026-10-14
The Imaging X-ray Polarimetry Explorer (IXPE) has opened a new window into the high-energy Universe, with the capability to measure the arrival time, arrival direction, energy, and, for the first time with the required sensitivity, the POLARIZATION of X-rays from BLACK HOLEs, neutron stars, and other cosmic sources of X-rays. In this paper, we discuss the use of Artificial Intelligence (AI) agents for the analysis of IXPE data. The pipeline combines an immutable code base with evolving knowledge databases. The generation of analysis projects makes use of a literature data base to judge the novelty of the proposed analysis projects. We emphasize that the analysis requires two types of expert knowledge: detailed instructions about how to reduce the X-ray data, and expert knowledge about how to interpret the results. We employ several levels of auditors that scrutinize the analysis plan, the analysis scripts, and the analysis results for data and method adequacy. The pipeline includes a staggered approach to interpret the analysis results. We present exemplary results from the pipeline applied to IXPE observations of Black Hole X-ray Binaries (BHXRBs) including comparisons of results from the analysis pipeline with published results and a systematic search for POLARIZATION degree and POLARIZATION angle variability in long IXPE observations. We critically discuss the performance of the pipeline and future avenues for improving it.
[abstract 46 / 63] (score: 2) - Title: Finding a RECONNECTion in a vortex-haystackAuthors: Abhishek Harikrishnan, Benjamin Musci, Adrien Lopez, Bartosz Protas, Adam Cheminet, Jean Le Bris, Jean-Marc Foucaut, Jean-Philippe Laval, Christophe Cuvier, Pierre Bragança, Bérengère Dubrulle,Comments:Subjects: physics.flu-dynCreated: 2026-10-09; Updated: 2026-10-14; Datestamp: 2026-10-14
Counter-rotating vortex RECONNECTion is a topology-transforming event that leads to strong vorticity amplification and is often associated with the most irregular regions of the velocity field. Detecting such events directly in turbulent flows is a major challenge due to the ambiguity inherent in the definition of a vortex and the rapid proliferation of intense small scale vortices. We develop a novel methodology by combining two tools. The first is a local in scale, space and time regularity indicator that isolates spatio-temporal regions of interest. The second is a RECONNECTion indicator that exploits a well-known property of vortex RECONNECTion namely, that the enstrophy (volume integral of the square of vorticity) flows from the symmetry to the collision plane. To examine the flow of enstrophy in the correct reference frame, a new method inspired by orientational order parameters in liquid crystals is developed. We then show a proof of concept for our RECONNECTion indicator by comparing it with diagnostic methods available in the literature. The method is validated on experimental datasets from a turbulent von Kármán flow at two different resolutions, one of which allows us to probe the flow below the Kolmogorov scale, $η$. Our findings suggest that counter-rotating vortex RECONNECTion could be a potential mechanism for the creation of motions at scales below $η$.
[abstract 47 / 63] (score: 2) - Title: A New Degree of Freedom in Stellarator Coil DesignAuthors: Sophia A. Henneberg, Annika Zettl,Comments:Subjects: physics.plasm-phCreated: 2026-10-09; Updated: 2026-10-14; Datestamp: 2026-10-14
Reversed toroidal field (RTF) coils introduce a new degree of freedom in stellarator coil design. While the total plasma-linked current is fixed by Ampere's law, compensating RTF currents allow the modular-coil current to exceed this value without altering the net linkage. This redistribution decouples key coil constraints and modifies the external coil geometry without significantly compromising the confining MAGNETic field. As a result, the achievable coil-plasma separation can be increased in the configurations studied, potentially enabling more compact stellarator designs.
[abstract 48 / 63] (score: 2) - Title: Post-Newtonian secular dynamics of hierarchical triples II. Canonical derivation of the 1PN\,$\times$\,quadrupole cross terms and of the quadrupole-squared termAuthors: Hideyoshi Arakida,Comments: 24 pages, 9 figuresSubjects: gr-qcCreated: 2026-10-10; Updated: 2026-10-14; Datestamp: 2026-10-14
We derive the secular Hamiltonian of a hierarchical triple from the 1PN ADM three-body Hamiltonian by a two-stage Lie-Hori-Deprit transformation carried out entirely in canonical variables, and use it to settle the RELATIVISTIC cross terms left open in Paper I. A bookkeeping rule enumerates all contributions to each order in the 1PN parameter $δ$ and the hierarchy parameter $\varepsilon$. The 1PN monopole interaction reduces to a renormalization of the inner mass by its binding energy, and the order $δ\varepsilon^{3/2}$, at which Lim and Rodriguez (LR) found a libration term, is empty. The electric and MAGNETic 1PN $\times$ quadrupole cross terms agree exactly with the effective-field-theory result of Kuntz, Serra, and Trincherini; for the MAGNETic term this is the first independent derivation. We give the next-to-leading order 1PN $\times$ quadrupole term in closed form; it depends on the outer argument of pericenter $ω_2$. At quadrupole-squared order we obtain the complete secular Hamiltonian, which generates the secular equations of Will and of Conway and Will; its $2ω_2$ harmonic is a gauge term, removable even on the commensurability between the ZLK period and the nodal precession, by a generator given in closed form via Tremaine's fictitious time. The EIH and ADM descriptions coincide at 1PN order; the formulations differ only in the definition of the elements, for which we give the osculating-contact map. In secular integrations of LR's triples, the eccentricity enhancement with the octupole is controlled by the $ω_2$-dependent part of the next-to-leading order term and is two to three times that of Paper I, while LR's accelerated mergers remain absent.
[abstract 49 / 63] (score: 2) - Title: Plasma-neutral collision operators for hydrogen isotopes: kinetic and gyrokinetic descriptions, comparison to fluidAuthors: Matthieu Protais, Guilhem Dif-Pradalier, Yanick Sarazin, Virginie Grandgirard, Yannick Marandet, Srikanth Sureshkumar, Naren Varadarajan,Comments:Subjects: physics.plasm-phCreated: 2026-10-10; Updated: 2026-10-14; Datestamp: 2026-10-14
Plasma-neutral interactions critically affect the edge dynamics of MAGNETically confined fusion devices. Neutral atoms modify ion and electron velocity distributions, potentially affecting local instabilities Standard fluid models simplify these processes (namely charge exchange, ionization and recombination) using Maxwellian assumptions and linearized source terms. We revisit these assumptions for a hydrogen plasma interacting with hydrogen atoms. We derive plasma-neutral interaction terms in the kinetic and gyrokinetic frameworks. Accounting for velocity-dependent differential cross-sections, the model captures the kinetic impact of inelastic collisions on ions and electrons beyond energy and momentum exchange. We demonstrate that the fluid moments of the kinetic model reduce to standard fluid source terms under the appropriate assumptions of Maxwellianity and linearity. We compare the kinetic model with fluid models through their effects on distribution functions and fluid moments. Substantial discrepancies are observed, even for Maxwellian distributions. For charge exchange, the kinetic model yields momentum and energy exchange rates up to twice those predicted by fluid descriptions. We show that a fluid treatment of ionization greatly overestimates the mean kinetic energy of the produced electrons. These results highlight the limitations of fluid descriptions and the importance of kinetic effects in edge-plasma momentum and energy exchange.
[abstract 50 / 63] (score: 2) - Title: Cosmology & Astrophysics of the Dark Dimension with Bulk Majorana NeutrinosAuthors: Luis A. Anchordoqui, Cumrun Vafa,Comments: 9 pages revtexSubjects: hep-ph astro-ph.CO hep-thCreated: 2026-10-10; Updated: 2026-10-14; Datestamp: 2026-10-14
Recently, the possibility of having sterile Majorana neutrinos charged under $B-L$ gauge symmetry in the bulk of the dark dimension has been explored. We point out a cosmological restriction on the Majorana mass of bulk neutrinos leading to mass $\gtrsim 100~{\rm GeV}$. This avoids the over-production of Kaluza-Klein neutrino towers in the early universe thus resolving the cosmological neutrino catastrophe of extra dimension scenarios. If the mass of the bulk neutrino is at the lower end of this bound, it can potentially also explain the recently observed FERMI halo excess on gamma rays through the evaporation of long-lived 5d (i.e. dark) BLACK HOLEs through Hawking radiation to bulk neutrinos, which promptly decay into standard model particles.
[abstract 51 / 63] (score: 2) - Title: Anisotropic Radiation in Super-Eddington Active Galactic Nuclei: The Responsivity of Broad-Line Regions to Continuum VariabilityAuthors: Feng-Na Fang, Pu Du, Jian-Min Wang,Comments: 24 pages, 18 figures, 1 table, accepted for publication in the Astrophysical JournalSubjects: astro-ph.GACreated: 2026-10-11; Updated: 2026-10-14; Datestamp: 2026-10-14
Anisotropic ionizing radiation is a natural theoretical expectation for super-Eddington accretion in ACTIVE GALACTIC NUCLEi (AGNs), implying that the ionizing flux incident on the broad-line region (BLR) clouds differs from that measured along the observer's line of sight. Reverberation mapping studies have revealed systematically shortened time lags of the broad H$β$ emission line relative to continuum variations in super-Eddington AGNs, a phenomenon that can be naturally interpreted as a consequence of anisotropic ionizing continuum radiation. To further investigate this anisotropy, we perform a systematic analysis of the H$β$ line responsivity, defined as the ratio of the variability amplitude of H$β$ to that of the driving continuum, for both sub- and super-Eddington AGNs. By combining the effective responsivities measured relative to the driving continuum, after correcting for the continuum--emission-line delay, with photoionization calculations, we infer the ionizing radiation field received by their BLRs. We find that, in super-Eddington AGNs, the ionizing flux inferred from the H$β$ responsivity differs significantly from that observed along the line of sight, whereas the two are in closer agreement in sub-Eddington AGNs. These results provide compelling evidence for strong anisotropy of the incident ionizing radiation in super-Eddington AGNs. We conclude by discussing the broader implications of this anisotropy, including its potential relevance to the "little red dots" recently discovered by the James Webb Space Telescope.
[abstract 52 / 63] (score: 2) - Title: A reduced model for neoclassical transport in non-axisymmetric MAGNETic configurationsAuthors: Y. Ban, X. Garbet, R. Varennes, Z. Qu, K. Lim, Y. Sarazin, A. Ibrahim, Y. C. Tay, B. B. Ang,Comments: 53 pages, 19 figuresSubjects: physics.plasm-phCreated: 2026-10-11; Updated: 2026-10-14; Datestamp: 2026-10-14
A unified framework is proposed to compute a neoclassical equilibrium for tokamaks with non-axisymmetric MAGNETic perturbations, based on a Hamiltonian description combined with a variational approach that relies on a principle of minimum entropy production. This approach allows for a transparent identification of the respective contributions from different classes of trapped particles in MAGNETic well minima. Analytic expressions are derived for specific collisionality regimes, and a fast and efficient numerical procedure is devised to compute the entropy production rate. Finding the extremum of the entropy production leads to tractable expressions of transport coefficients that can be computed quickly and efficiently.
[abstract 53 / 63] (score: 2) - Title: Radial increase of the compensated interplanetary MAGNETic field magnitude as a result of the growth of spherically polarized Alfvén wavesAuthors: Stuart D. Bale, Timothy S. Horbury, Lorenzo Matteini,Comments: 13 pages, 5 figuresSubjects: astro-ph.SR physics.plasm-phCreated: 2026-10-11; Updated: 2026-10-14; Datestamp: 2026-10-14
Measurements from the NASA Parker Solar Probe (PSP) mission demonstrate that inside $\sim20$ solar radii ($\Rs$) the magnitude of the interplanetary MAGNETic field does not fall off simply as $1/R^2$, with $\avg{|B|}\,R^2$ 15--20\% below its value at $\sim60\,\Rs$. Here we use PSP MAGNETic field measurements over $10.6$--$56.8\,\Rs$ to show that the outward rise of $\avg{|B|}\,R^2$ is not due to the global structure of the heliospheric MAGNETic field or proximity to the heliospheric current sheet but is the direct result of the growth of large-amplitude, spherically polarized Alfvén waves (so-called `switchbacks'). Over the same distance range, $\avg{B_R}\,R^2$ stays constant, so that the sector-signed radial flux is conserved. The wave amplitude $ε= B_{\perp,{\rm rms}}/\avg{B_\parallel}$ grows from $0.26$ to $0.57$ as $R^{1/2}\cosα$, and $\avg{|B|}/\avg{B_R}$ rises by $20\%$. A simple model parametrized by the broadening of the distribution of deflection angles reproduces the effect to high accuracy. These results demonstrate that as the relative wave amplitudes grow with increasing solar distance, a dynamo-like process operates to enhance the field magnitude by up to $20\%$. By enhancing MAGNETic pressure this has implications for the large scale solar wind structure in the low-beta inner heliosphere, as well as partially resolving the long-standing discrepancy between remote measurements of the solar MAGNETic field and those made in situ by earlier missions farther from the Sun.
[abstract 54 / 63] (score: 2) - Title: Integration of a CME Flux Rope Model with Magnetic Field Draping in Heliospheric SimulationsAuthors: Ranadeep Sarkar, Jens Pomoell, Emilia Kilpua, Eleanna Asvestari,Comments: Accepted for publication in ApJSubjects: astro-ph.SRCreated: 2026-10-12; Updated: 2026-10-14; Datestamp: 2026-10-14
Accurate prediction of the MAGNETic structure of interplanetary coronal mass ejections (ICMEs) remains a key challenge in space weather forecasting. Despite several efforts using global MHD modeling, it remains difficult to deduce a flux-rope solution that can accurately and reliably reproduce the MAGNETic structure of a CME. We present FROST (Flux Rope embedded in the Solar Magnetic Field), a new flux-rope model implementation within the European Heliospheric Forecast Information Asset (EUHFORIA), featuring an initially force-free toroidal flux rope embedded in the low-coronal MAGNETic field. FROST employs a novel embedding technique that self-consistently generates a draping MAGNETic field around the flux-rope, ensuring continuity of the normal MAGNETic field component at the CME boundary. The dynamics of the flux-rope in the low and middle corona is solved by a non-uniform advection constrained by the observed kinematics of the event. This results in a global, non-toroidal, stretched loop-like MAGNETic structure. At heliospheric distances, the evolution is modeled as an MHD process using EUHFORIA. We validate the FROST model implementation by simulating the CME event of 2013 April 11 and comparing the results with in situ MAGNETic field measurements at 1 au. The modeled MAGNETic field profiles of the flux-rope exhibit strong agreement with the observations, with correlation coefficients ranging from 0.64-0.93 for Bx, 0.92-0.95 for By, and 0.82-0.87 for Bz component of the MAGNETic field. These results demonstrate the capability of the proposed flux-rope model to significantly improve ICME MAGNETic field prediction, highlighting its strong potential for advancing space-weather forecasting capabilities.
[abstract 55 / 63] (score: 2) - Title: Quasinormal modes of rotating BLACK HOLEs with ultralight scalar fieldsAuthors: Leif Lui, Adrian Ka-Wai Chung,Comments: 18 pages, 10 figuresSubjects: gr-qc astro-ph.HECreated: 2026-10-12; Updated: 2026-10-14; Datestamp: 2026-10-14
We report the first accurate computation of the leading-order shifts in the quasinormal-mode frequencies of rapidly rotating BLACK HOLEs surrounded by massive scalar fields with nonminimal curvature coupling. For fields with reduced Compton wavelengths no shorter than the black-hole mass scale, the numerical errors in the frequency shifts are typically $10^{-8} - 10^{-5}$ for dimensionless spins between 0 and 0.9, and at most $\mathcal{O}(10^{-3})$ next to the scalar-mass threshold. Our results open up the possibility of searching for ultralight scalar particles, prime dark-matter candidates, using existing gravitational-wave signals.
[abstract 56 / 63] (score: 2) - Title: Implicit PIC Simulations of Hydrogen Plasmas with Intense Negative Ion ProductionAuthors: Denis Eremin,Comments:Subjects: physics.plasm-phCreated: 2026-10-12; Updated: 2026-10-14; Datestamp: 2026-10-14
High-density plasma discharges in hydrogen operating at low pressures are of considerable interest for negative ion production used in many applications. Their weak collisionality requires a kinetic, nonlocal description, and a popular approach is to model such discharges numerically using the particle-in-cell (PIC) method combined with Monte Carlo collisions (MCC). However, the most commonly used explicit momentumconserving variant of this method is highly inefficient because it must resolve both the Debye length and the plasma period. In this context, the implicit energy-conserving PIC/MCC scheme appears to be an attractive alternative, as it can model the plasmas of interest using their actual parameters without resorting to artificial scaling techniques. This work considers simulations of two types of high-density plasma discharges performed using electroMAGNETic or electrostatic energy-conserving PIC/MCC codes in hydrogen, and discusses the observed negative ion production.
[abstract 57 / 63] (score: 2) - Title: Superconductivity from alterMAGNETic fluctuations: the crucial role of sublattice POLARIZATIONAuthors: Mats Barkman, Andreas Kreisel, Brian M. Andersen,Comments: 16 pages, 16 figuresSubjects: cond-mat.supr-con cond-mat.mtrl-sciCreated: 2026-10-12; Updated: 2026-10-14; Datestamp: 2026-10-14
Unconventional superconductivity in correlated systems often appears in the vicinity of a MAGNETically ordered state. This situation is also relevant for alterMAGNETs, characterized by a nonRELATIVISTIC spin-split electronic structure in the presence of Néel order. Many proposed alterMAGNETic candidates, however, never cross the MAGNETic instability. We study superconductivity arising from alterMAGNETic fluctuations in such systems and show that the sublattice POLARIZATION (SLP) of the normal-state bands plays a pivotal role in determining the superconducting state. SLP, an inherent property of alterMAGNETic band structures that persists even without MAGNETic order, prevents Cooper pairs from forming between different sublattices. This suppresses pairing mediated by the nearest-neighbor antiferroMAGNETic exchange, which favors spin-singlet superconductivity, and leaves longer-range same-sublattice bonds dominant. When the next-nearest-neighbor exchange is ferroMAGNETic, as expected for frustration-free Néel order, this results in spin-triplet superconductivity. This mechanism is fundamentally different from that in alterMAGNETs with long-range Néel order, where the spin-split FERMI surfaces favor equal-spin pairing. Finally, when longer-range interactions in the disordered phase instead favor singlet pairing, SLP leads to singlet states with characteristic properties distinct from nearest-neighbor pairing states.
[abstract 58 / 63] (score: 2) - Title: Nearly pristine gas in a galaxy 1 billion years after the Big BangAuthors: Sarah E. I. Bosman, Frederick B. Davies, Louise Welsh, Emanuele P. Farina, Prakash Gaikwad, Benedetta Spina, Barun Maity, Ryan Cooke, Klaudia Protušová, Valentina D'Odorico, Eduardo Bañados, James S. Bolton, Rebecca L. Davies, Xiaohui Fan, Martin G. Haehnelt, Joseph F. Hennawi, Tahlia J. Hill, Seyeon Hwang, Vid Iršič, Laura Keating, Girish Kulkarni, Samuel Lai, Emma V. Ryan-Weber, Lasse Seyberlich, Molly Wolfson,Comments: Accepted in NatureSubjects: astro-ph.GACreated: 2026-10-12; Updated: 2026-10-14; Datestamp: 2026-10-14
Excitation of carbon and oxygen ions is the primary mechanism by which collapsing gas clouds dissipate heat to form new stars. At early cosmic times, in galaxies with chemically pristine gas, many stars are expected to have masses far larger than the mass of our sun due to the deficit in these elements. We searched for ultra-metal-poor galaxies using their spectroscopic absorption signatures in front of bright background QUASARs, employing the new GHOST high-resolution spectrograph. Here we report the discovery of the first galaxy containing a reservoir of neutral hydrogen gas with metallicity below the ultra-metal-poor threshold: with a measured carbon-to-hydrogen ratio 11,000 times lower than the Sun, it is the most pristine ever found by a factor of four. UMP-DLA-1 is the only known galaxy with measured carbon and oxygen abundances too low to enable efficient formation of stars with solar mass or below. The low metallicity alone therefore guarantees a top-heavy stellar population, providing a direct view of the chemical composition imprinted by massive low-metallicity stars that perished long before the present day: an elevated oxygen-to-carbon ratio. The abundance pattern of UMP-DLA-1 is likely a close representation of the atomic yields of first- or early second-generation stars.
[abstract 59 / 63] (score: 2) - Title: Onset condition of the ramified-JET regime: an experimental and theoretical studyAuthors: Bor Zupan, Jernej Kušar, Božidar Šarler,Comments: 17 pages, 6 figuresSubjects: physics.flu-dynCreated: 2026-10-12; Updated: 2026-10-14; Datestamp: 2026-10-14
This study experimentally and theoretically investigates the electrically induced transition of a gas-focused liquid JET into a rim-emitting sheet. Ultra-high-speed imaging was used to examine the effects of applied voltage, gas and liquid flow rates, and liquid properties on sheet formation and breakup. Fully developed, quasi-stable sheets formed with ethanol, whereas isopropanol exhibited only initial sheet formation. Increasing voltage promoted sheet stretching, finer and more numerous rim JETs, and a narrower spray. Higher gas flow rates shifted the transition towards the nozzle and produced finer structures, while higher liquid flow rates generated larger sheets with thicker rims. A first-order theoretical model assumes an equipotential interface and neglects finite charge relaxation, hydrodynamic perturbations, and nonlinear evolution. It balances destabilizing Maxwell-pressure perturbations against restoring capillary-pressure perturbations on a conducting cylindrical JET. The model identifies the elliptic azimuthal mode, m = 2, as the first unstable mode leading to sheet formation and predicts a critical electric Bond number of 3. Predicted onset voltages agree with measurements within 20%, and the threshold was consistent with published ramified-electrospray observations. The agreement with experiments supports electrocapillary symmetry breaking as the mechanism of onset and provides a compact, physically grounded criterion for predicting the transition from electrified JETs to rim-emitting sheets.
[abstract 60 / 63] (score: 2) - Title: Hamiltonian surface charges in General Parallel RelativityAuthors: Tomi Koivisto,Comments: 30 pagesSubjects: gr-qcCreated: 2026-10-12; Updated: 2026-10-14; Datestamp: 2026-10-14
General Parallel Relativity is a dynamically equivalent formulation of Einstein gravity in which the parallel frame supplies explicit boundary reference data. In this formulation, finite-region energy-momentum and horizon entropy arise as distinct Hamiltonian surface charges. Diffeomorphisms along canonical frame directions define a quasi-local energy-momentum including a matter surface term, while normal-plane boosts at a smooth horizon give entropy. These covariant formulas are applied to the Reissner-Nordström BLACK HOLE and to a dilatonic charged BLACK HOLE. In both examples, the matter contribution and its Legendre transform complete the Misner-Sharp mass into the Hamiltonian energy appropriate to the chosen electroMAGNETic boundary datum. The resulting horizon charges satisfy the thermodynamic relation obtained independently from the Euclidean boundary action.
[abstract 61 / 63] (score: 2) - Title: QUARZ: a quasi-static particle-in-cell code with non-uniform radial grids for plasma wakefieldsAuthors: Alexander Pukhov, Thomas C. Wilson,Comments:Subjects: physics.plasm-phCreated: 2026-10-12; Updated: 2026-10-14; Datestamp: 2026-10-14
We present a quasi-static particle-in-cell scheme for beam-driven plasma wakefields in cylindrical geometry that works on an arbitrary non-uniform radial grid. The field equations are discretized with hat-function finite elements and conservative finite volumes on any monotone set of radial nodes, and the transverse MAGNETic field is obtained explicitly, without iterations, following Baxevanis and Stupakov. An optional azimuthal mode $m=1$ describes beam offsets, tilts and hosing. The discretization keeps the discrete Gauss law exact, deposits a uniform plasma exactly on every node including the axis, and remains second-order accurate on smoothly stretched grids. Resolution can therefore be placed where the physics needs it. For a tightly focused witness beam that pulls the plasma ions onto the axis, a grid that is fine only near the axis gives the same near-axis fields as a uniform grid with the same axis resolution, with thirty times fewer cells and in thirty times less computing time. Such a grid also resolves the singular closure of a cold-plasma bubble, which a uniform grid hides by smoothing it over one cell; smoothing the plasma sources over a fixed length, chosen independently of the grid, regularizes the closure and makes the wake behind it converge. The scheme is implemented in the open-source C++/Kokkos code QUARZ (Quasistatic Arbitrary-resolution RZ), which runs on CPUs and GPUs and uses MPI with a pipelined decomposition along the co-moving coordinate. Simulations of the self-modulation of the AWAKE proton bunch agree with the three-dimensional code HiPACE++. QUARZ is, to our knowledge, the first production-grade simulation code in plasma physics that is \emph{zero-touch}: all of its source code, tests and documentation were written by an AI agent directed by a physicist who did not write a single line of the code.
[abstract 62 / 63] (score: 2) - Title: Quasibound states of charged Dirac fields around Einstein-Euler-Heisenberg BLACK HOLEsAuthors: Nodirbek Anarboev, Javlonbek Khasanov, Javlon Rayimbaev, Bobomurat Ahmedov,Comments: 12 pages, 6 figuresSubjects: gr-qcCreated: 2026-10-12; Updated: 2026-10-14; Datestamp: 2026-10-14
We study quasibound states of a massive charged Dirac field on the Einstein--Euler--Heisenberg (EEH) BLACK HOLE, the extension of Reissner--Nordström (RN) by the leading weak-field vacuum-POLARIZATION term of QED. We derive the background to first order in the Euler--Heisenberg coupling $a$. We show that it admits a nondegenerate horizon at $Q=M$ and an extremal charge $Q_{\rm ext}=M[1+a/(40M^2)+\mathcal{O}(a^2)]>M$, with horizon data that depend on $\sqrt a$ near extremality. From the separated radial equations, we derive an identity that excludes real-frequency quasibound states on any background of this class, so damped branches cannot become unstable. Since the EEH corrections first enter at $\mathcal{O}(r^{-5})$ in the electrostatic potential, the trapping condition $Mμ^2-qQω_R>0$ and the hydrogenic spectrum coincide with RN, and no fine-structure-order splitting arises. Two-sided shooting with a Muller root finder shows that the real frequencies shift only by near-zone amounts that are linear in $a$ and strongly suppressed with angular momentum. The damping rates respond in a branch-dependent way. At $Q/M=0.99$ the $\ell=0$ ground state becomes slightly longer-lived, while the $(n_r,j,\ell,λ)=(0,\tfrac32,1,-2)$ state decays up to $80\%$ faster for $a/M^2\le1$, and near the trapping threshold the damping rate increases by up to $60\%$. Switching on the metric and potential corrections separately, together with a WKB analysis of the inner barrier, identifies the mechanisms: Coulomb screening always increases leakage, while the metric correction controls the sign and size of the $\ell$-dependent effect. Characteristic time-domain evolutions with Richardson-extrapolated matrix-pencil extraction reproduce the frequency-domain shifts.
[abstract 63 / 63] (score: 2) - Title: Vanishing Love Numbers of Kerr-Newman Black HolesAuthors: Sumanta Chakraborty, Takuya Katagiri, Paolo Pani, Jun-Xi Shi,Comments: Letter: 5 pages; Supplemental Material: 8 pagesSubjects: gr-qc astro-ph.HE hep-thCreated: 2026-10-12; Updated: 2026-10-14; Datestamp: 2026-10-14
Tidal Love numbers characterize the conservative response of compact objects to external perturbations and provide a powerful probe of their nature. While the static Love numbers of Schwarzschild, Kerr, and Reissner--Nordström BLACK HOLEs remarkably vanish, the tidal response of a generic Kerr--Newman BLACK HOLE has remained unexplored due to the intrinsic coupling between gravitational and electroMAGNETic perturbations. Exploiting a recent breakthrough in the separability of these perturbations, we analytically determine the static tidal response of the most general stationary BLACK HOLE in four-dimensional Einstein--Maxwell theory. For arbitrary multipole order, charge, and spin, we show that the entire matrix of conservative Love numbers vanishes, including the mixed gravito-electroMAGNETic couplings. We also compute the nonvanishing static dissipative response induced by frame dragging.
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