Current date: 2026-10-30

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Created/updated limit: 2026-10-23 (7 days ago)

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OAI-PMH request: http://export.arxiv.org/oai2?verb=ListRecords&from=2026-10-30&until=2026-10-30&set=physics&metadataPrefix=arXiv

Scoring abstracts

Number of records retrieved: 1300

Keyword score statistics

score 11 -- 1 abstracts

score 7 -- 4 abstracts

score 6 -- 7 abstracts

score 5 -- 5 abstracts

score 4 -- 5 abstracts

score 3 -- 14 abstracts

score 2 -- 34 abstracts

in total -- 70 abstracts

Articles that appeared on 2026-10-30

[abstract 1 / 70] Wow! (score: 11)
arXiv:2610.37902 [pdf, ps, other]

Title: Validating an X-ray-based method for identifying FERMI BLAZARs

Authors: J. L. Weiss, E. J. Marchesini, I. Andruchow, N. Masetti,

Comments:

Subjects: astro-ph.HE astro-ph.GA

Created: 2026-10-27; Updated: 2026-10-30; Datestamp: 2026-10-30

Context. Blazars are the main population of ACTIVE GALACTIC NUCLEi (AGNs) detected in gamma rays by FERMI. However, around 34% of FERMI sources remain unidentified, partly due to their large positional uncertainties, motivating multiwavelength methods to identify possible counterparts. Aims. We evaluate a method proposed to identify BL Lacertae (BL Lac) candidates among unidentified FERMI sources based on their X-ray properties, using SWIFT-XRT observations. Methods. We examined published optical spectra for an initial sample of 148 X-ray-selected candidates. We found 71 sources with spectra spatially consistent with the proposed associations and reassessed their classifications using standard BLAZAR criteria. We then compared these classifications with the method's initial predictions. Results. Of the 71 proposed counterparts, 80.28% are classified as BL Lac objects and 87.32% as possible gamma-ray-emitting AGNs, supporting the effectiveness of the X-ray-based selection. We also identify four Seyfert galaxies, suggesting that the method is sensitive to this class despite its rarity among gamma-ray emitters. Conclusions. Our results show that X-ray observations are effective for selecting BL Lac candidates among unidentified FERMI sources and support future spectroscopic follow-up campaigns. The high fraction of BL Lacs and AGNs suggests that BLAZARs may account for a substantial part of the unidentified gamma-ray population. The Seyfert identifications also raise questions about the origin of high-energy emission in AGNs not typically associated with RELATIVISTIC JETs, highlighting the need for further multiwavelength observations.

[abstract 2 / 70] Wow! (score: 7)
arXiv:2610.10522 [pdf, ps, other]

Title: Widespread steep X-ray spectra of luminous $z=5.85-7.64$ QUASARs and their implications for future X-ray surveys

Authors: 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: Accepted for publication in A&A after minor revisions

Subjects: astro-ph.HE astro-ph.GA

Created: 2026-10-29; Updated: 2026-10-30; Datestamp: 2026-10-30

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 $z = 5.85-7.64$ (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 3 / 70] Wow! (score: 7)
arXiv:2610.37758 [pdf, ps, other]

Title: Thinner Disks Struggle to Launch Jets: GRMHD Simulations of Magnetic Field Generation and Transport

Authors: Jonatan Jacquemin-Ide, Mitchell C. Begelman, Henrik Latter, Jason Dexter, Alexander Tchekhovskoy,

Comments: Submitted to MNRAS comments welcomed

Subjects: astro-ph.HE

Created: 2026-10-27; Updated: 2026-10-30; Datestamp: 2026-10-30

Relativistic JETs are observed in some accreting black-hole systems but not others. In X-ray binaries, JET production is closely associated with geometrically thicker accretion states, suggesting that disk thickness may influence the conditions for JET launching. We investigate this connection using three-dimensional GRMHD simulations of disks with $h/r=0.1$--$0.3$, initialized with a toroidal MAGNETic field with plasma $β=5$. We find that the MAGNETorotational instability (MRI) generates large-scale poloidal fields through non-axisymmetric shearing waves, with an additional contribution from axisymmetric induction through stretching by channel-like modes. The resulting mean fields become progressively weaker as the disk becomes thinner. Because these fields regulate MRI turbulence, thinner disks exhibit weaker angular-momentum transport and accrete more slowly than the standard $v_{\rm acc}\propto(h/r)^2$ thin-disk scaling would predict. The MAGNETic-flux transport velocity remains comparable to the accretion velocity, so weaker field generation and slower transport combine to strongly suppress black-hole flux accumulation at smaller $h/r$. Correspondingly, the thinnest disk ($h/r=0.1$) produces an electroMAGNETic JET efficiency of only $η_{\rm{EM}}\sim1\%$, while the thickest disk reaches the MAGNETically arrested disk (MAD) state and attains $η_{\rm{EM}}\geq100\%$. Using the measured large-scale MAGNETic flux distribution and transport velocities, we estimate the time required to accumulate MAD-level MAGNETic flux. Only the $h/r\sim0.3$ disk reaches MAD in the duration of our simulations, at $t\simeq2\times10^4\,r_g/c$, whereas for $h/r=0.1$ we estimate a timescale of $\sim10^8\,r_g/c$. These results link disk geometry to MAGNETic-flux accumulation and JET launching, with direct implications for the timescales over which JETs can emerge in transient accreting systems.

[abstract 4 / 70] Wow! (score: 7)
arXiv:2610.38432 [pdf, ps, other]

Title: Migration Traps as Variability Attractors. II. Nonmonotonic X-Ray Timing Signatures of Embedded Stellar-Mass Black Holes in AGN Disks

Authors: Jing-Tong Xing, Tong Liu, Mouyuan Sun, Zhen-Yi Cai, Ya-Ping Li, Shuying Zhou, Da-Bin Lin, Jian-Min Wang,

Comments: 12 pages, 3 figures, 2 tables

Subjects: astro-ph.HE astro-ph.GA

Created: 2026-10-28; Updated: 2026-10-30; Datestamp: 2026-10-30

Stellar-mass BLACK HOLEs (sBHs) embedded in ACTIVE GALACTIC NUCLEus (AGN) disks may affect X-ray variability through MAGNETic RECONNECTion. As sBHs migrate and accumulate near migration traps, they disturb the disk MAGNETic field and trigger RECONNECTion events that heat the disk and eject plasma into the overlying corona. The injected plasma dissipates kinetic energy and can trigger the release of MAGNETic energy already stored in the corona. We calculate the resulting coronal X-ray emission and the disk ultraviolet (UV) variability, including the disk thermal response and reprocessing of incident X-rays. We find that embedded sBHs can initially enhance short-timescale X-ray variability, but the variability becomes suppressed as more sBHs accumulate in the disk. At higher mass accretion rates through AGN disks, this suppression appears earlier. As sBH-associated RECONNECTion events become more frequent, their active regions increasingly overlap, reducing the MAGNETic energy available to each event from the corona. We also find that variations in the disk ultraviolet (UV) emission follow the X-ray variations with a shorter delay than in the model without sBHs. These results suggest that a growing population of embedded sBHs does not necessarily produce stronger short-timescale X-ray variability.

[abstract 5 / 70] Wow! (score: 7)
arXiv:2610.39656 [pdf, ps, other]

Title: Towards an Astronomical Use of New-Generation Geodetic Observations

Authors: Víctor Pérez-Díez,

Comments: PhD thesis, Universidad Complutense de Madrid (UCM). Supervisors: Iván Martí-Vidal and Rafael Bachiller García. Defended on 19 October 2026. 230 pages

Subjects: astro-ph.IM

Created: 2026-10-29; Updated: 2026-10-30; Datestamp: 2026-10-30

This thesis explores the astronomical use of observations from the VLBI Global Observing System (VGOS), a next-generation geodetic network designed to improve the precision of terrestrial and celestial reference frames and Earth orientation parameters. Although primarily conceived for geodesy, its wide frequency coverage and regular monitoring of compact ACTIVE GALACTIC NUCLEi (AGN) provide valuable opportunities for astrophysics. We develop a calibration pipeline that transforms VGOS correlator outputs into full-POLARIZATION, calibrated visibilities suitable for astronomical imaging. The procedure combines linear-to-circular POLARIZATION conversion, instrumental phase and amplitude calibration, and a new wideband global fringe-fitting algorithm that accounts for dispersive ionospheric effects. Regularized maximum likelihood imaging is then used to reconstruct multi-frequency intensity and polarimetric images. The pipeline is applied to the BLAZAR 1803+784 and five additional AGN: 3C418, 0059+581, 0613+570, 1849+670, and 2229+695. We measure frequency-dependent core shifts, spectral indices, and Faraday rotation properties. For 1803+784, the fitted core-shift index is $k_r = 0.73^{+0.12}_{-0.19}$, suggesting departures from a simple conical JET in energy equipartition. Finally, we apply the reconstructed source models to correct structure-dependent effects in geodetic VLBI observables. The correction reduces closure-delay scatter and post-fit residuals for strongly structured sources, particularly 3C418, while its effectiveness depends on source variability and the temporal proximity of the imaging observations. These results demonstrate the dual scientific value of VGOS as a powerful multi-frequency astronomical VLBI instrument and as a means of improving geodetic measurements.

[abstract 6 / 70] Yes (score: 6)
arXiv:2509.16313 [pdf, ps, other]

Title: Numerical Modeling of Relativistic Effects in Synchrotron-Emitting Shocks

Authors: Ross Ferguson, Ben Margalit,

Comments: 27 pages, 8 figures. Matches version accepted to ApJ. Comments welcome

Subjects: astro-ph.HE

Created: 2026-10-28; Updated: 2026-10-30; Datestamp: 2026-10-30

Synchrotron emission is seen in a vast array of astrophysical transients, such as GAMMA-RAY BURSTs (GRBs), radio SUPERNOVAe, neutron star (NS) mergers, tidal disruption events (TDEs), and fast blue optical transients (FBOTs). Despite the ubiquity of SYNCHROTRON-emitting sources, modeling of the emergent flux from these events often relies on simplified analytic approximations. These approximations are inaccurate for high-velocity shocks, where special-RELATIVISTIC effects are important. Properly incorporating these effects considerably complicates calculations, and generally requires a numerical treatment. In this work we present a novel numerical model which solves the full radiative-transfer problem in SYNCHROTRON-emitting shocks, accounting for all RELATIVISTIC effects. This `full-volume' model is capable of calculating SYNCHROTRON emission from a shock of arbitrary velocity, and is designed to be flexible and applicable to a wide range of astrophysical sources. Using this new code, we evaluate the accuracy of more commonly-used approximate models. We find that the full-volume treatment is generally necessary once the shock proper-velocity exceeds $(Γβ)_{\rm sh}\gtrsim 0.1$, and that approximate models can be inaccurate by $\gtrsim$ an order-of-magnitude in trans-RELATIVISTIC shocks. This implies that there may be a bias in the inferred physical properties of some FBOTs, JETted TDEs, and other RELATIVISTIC explosions, where approximate analytic models are typically employed. The code associated with our model is made publicly available, and can be used to study the growing population of RELATIVISTIC SYNCHROTRON-emitting transients.

[abstract 7 / 70] Yes (score: 6)
arXiv:2605.09326 [pdf, ps, other]

Title: Characterizing the Scale Height and Filamentary Structure of Radiatively Cooled MADs

Authors: Akshay Singh, Damien Begue, Asaf Pe'er,

Comments: Accepted for publication in Astrophysical Journal after minor corrections

Subjects: astro-ph.HE

Created: 2026-10-28; Updated: 2026-10-30; Datestamp: 2026-10-30

Radiative cooling can strongly influence the structure and dynamics of BLACK HOLE accretion disks. Here, we perform general RELATIVISTIC MAGNETohydrodynamic (GR-MHD) simulations of MAGNETically arrested disks (MADs) around a non-spinning BLACK HOLE. Radiative cooling is consistently included in the simulations and its intensity is scaled by the mass accretion rate ranging from $10^{-7}$ to $10^{-4} \dot{M}_{\mathrm{Edd}}$. Considering SYNCHROTRON and bremsstrahlung emission, we quantify how radiative losses modify the disk structure and the accretion dynamics. In the inner MAD disk regions, accumulation of MAGNETic field regulates gas accretion, enforcing the gas into a discrete interchange-driven filamentary structure. We identify, both analytically and numerically, a transition mass accretion rate above which radiative cooling becomes faster than the heating, which is assumed to occur via local coupling to the MAGNETic field. Above this mass accretion rate, cooling substantially reduces the gas thermal pressure, leading to considerably thinner and denser accretion filaments, and a substantial increase in radiative efficiency, relative to lower accretion rates. We show that under these conditions, conventional measures of the disk scale height become misleading in MAD flows. We therefore introduce an alternative definition based on the polar position of the density maximum, which more robustly characterizes the filamentary structure of the disks in the presence of strong MAGNETic fields and cooling.

[abstract 8 / 70] Yes (score: 6)
arXiv:2607.13130 [pdf, ps, other]

Title: Synchrotron Emission from Cooled Particle Distributions

Authors: Ross Ferguson, Ben Margalit,

Comments: 27 pages, 7 figures. Matches version accepted to ApJ. Comments welcome!

Subjects: astro-ph.HE

Created: 2026-10-28; Updated: 2026-10-30; Datestamp: 2026-10-30

Synchrotron emitting electrons can lose energy (`cool') through various processes including radiative losses (e.g., SYNCHROTRON or inverse-Compton cooling) and adiabatic expansion. Such cooling will shift electrons in energy-space and therefore change the electron distribution function. This in turn alters the nature of SYNCHROTRON emission and absorption from these electrons. In past literature these effects have typically been considered using either simplified one-zone frameworks, or using numerical methods as part of more accurate local modeling. In this work we extend the latter `local' treatment by deriving analytic expressions that are both accurate and more computationally efficient than previous numerical approaches. Considering two concrete cases of injected power-law and thermal electron distribution functions, we derive analytic fitting functions for the resulting emission and absorption coefficients including the effects of cooling. These fitting functions can be applied to SYNCHROTRON afterglow modeling from a variety of astrophysical sources, such as GAMMA-RAY BURSTs (GRBs), luminous fast blue optical transients (LFBOTs), and JETted tidal disruption events (TDEs).

[abstract 9 / 70] Yes (score: 6)
arXiv:2610.31753 [pdf, ps, other]

Title: An Extra-nuclear Water Maser in NGC 1106 Likely Driven By An AGN Shock: Implications for Maser-based Black Hole Mass Measurements

Authors: Macon Magno, Emmanuel Momjian, Krista L. Smith, O. Ivy Wong, Travis C. Fischer, Michael J. Koss, Chenoa D. Tremblay,

Comments: Accepted to ApJ, 11 pages, 2 figures, 2 tables

Subjects: astro-ph.GA astro-ph.HE

Created: 2026-10-29; Updated: 2026-10-30; Datestamp: 2026-10-30

We present Very Large Array A-configuration ($0.13$'') 22 GHz spectral-line and continuum observations of the SWIFT-BAT detected Seyfert 2 galaxy, NGC 1106, aimed at localizing a water maser line offset from the host systemic velocity by 541 km s$^{-1}$. The 22 GHz continuum emission reveals a 352 pc extended structure within the nucleus of NGC 1106, and we spatially resolve the water maser emission to a compact region $\sim1$ kpc ($3.12$'') from the nucleus. Comparing our data with previous 22 GHz 1'' observations, we found that the water maser lies near the boundary of a radio extension aligned with the JET axis, likely arising from the interface between the ACTIVE GALACTIC NUCLEus (AGN) outflow and the host galaxy's ISM. To verify this, we compared the water maser in NGC 1106 to a known water maser in a star-forming region within the Milky Way, along with known extragalactic water masers associated with STAR FORMATION and AGN driven outflows. Overall, we found that the maser position, velocity offset, flux density, and alignment with the JET axis are consistent with an origin at the interface between the AGN outflow and the host ISM. Our results have important implications for maser-based BLACK HOLE mass measurements in which disk geometry is ambiguous. Since single-dish observations cannot spatially separate disk masers from outflow-driven masers, high-velocity maser features attributed to the accretion disk may also include contributions from kpc-scale shocks.

[abstract 10 / 70] Yes (score: 6)
arXiv:2610.38673 [pdf, ps, other]

Title: Black Hole Spin Evolution in Magnetized Accretion Flows

Authors: Danat Issa, Ore Gottlieb, Jonatan Jacquemin-Ide, Matthew Liska,

Comments: 20 pages, 8 figures (3 in appendix). Comments welcome. Submitted for publication

Subjects: astro-ph.HE astro-ph.GA astro-ph.SR

Created: 2026-10-28; Updated: 2026-10-30; Datestamp: 2026-10-30

Black hole (BH) spin grows as accretion supplies angular momentum and decreases as MAGNETically driven JETs remove it, driving the BH toward an equilibrium spin, $a_{\rm \star; eq}$. Existing estimates of $a_{\rm \star; eq}$ rely on general-RELATIVISTIC MAGNETohydrodynamic (GRMHD) simulations with fixed BH mass and spin, and cover only the extreme limits of horizon MAGNETic flux $ϕ\rightarrow0$ and MAGNETically arrested disks (MADs), $ϕ\approxϕ_{\rm MAD}$. We evolve the BH mass and spin in long 3D GRMHD simulations of radiatively inefficient accretion flows aligned or anti-aligned with the BH spin. We find the spin-up parameter as a function of BH spin and $ϕ/ϕ_{\rm MAD}$, and derive the equilibrium spin as a continuous function of flux, $a_{\rm \star; eq}(ϕ/ϕ_{\rm MAD})$. The equilibrium spin falls steeply with flux, from $a_{\rm \star; eq}\approx0.9$ in weakly MAGNETized flows through $a_{\rm \star; eq}(ϕ/ϕ_{\rm MAD}=0.5)\approx0.5$ to $a_{\rm \star; eq}(ϕ/ϕ_{\rm MAD}=1)\approx0.06$ in sustained MADs. In weakly MAGNETized flows, a slowly spinning BH must accrete at least its initial mass to reach equilibrium, whereas MADs spin down rapidly rotating BHs after accreting less than half of it. However, as the BH grows, the growing gravitational radius and enhanced inflow reduce $ϕ/ϕ_{\rm MAD}$, driving disks whose MAGNETic-flux supply cannot keep pace out of the MAD state and allowing the BH to transition from spin-down to spin-up. The final spin thus depends on both the MAGNETic flux history and the accreted mass. We discuss implications for a variety of BH-powered engines and provide a subgrid prescription for galaxy-scale simulations and population studies.

[abstract 11 / 70] Yes (score: 6)
arXiv:2610.39792 [pdf, ps, other]

Title: RAKI: High-Order Alternative Finite Differences for General Relativistic Magnetohydrodynamics

Authors: Rahime Matur, Beyhan Karakas, Ian Hawke, Nils Andersson,

Comments: 21 pages, 12 figures, 1 table

Subjects: astro-ph.HE gr-qc hep-ph physics.comp-ph

Created: 2026-10-29; Updated: 2026-10-30; Datestamp: 2026-10-30

Binary neutron star (BNS) and BLACK HOLE--neutron star mergers are among the most important multimessenger sources. Observations of these events could provide valuable insights into several unresolved phenomena, ranging from the efficiency of MAGNETic field amplification during and after mergers to the formation of MAGNETars and JETs. Understanding these phenomena requires accurate modelling of MAGNETic field evolution, which remains a challenge for state-of-the-art general RELATIVISTIC MAGNETohydrodynamics (GRMHD) simulations. In this work, we present \texttt{RAKI} (Relativistic Astrophysics Code Implementation of the Alternative Finite Difference Approach for GRMHD), the first GRMHD code to simulate BNS mergers using high-order alternative finite-difference methods with adaptive-order WENO (AFD-WENO-AO) reconstruction and a fully non-staggered, node-centred vector-potential formulation. The code achieves up to ninth-order convergence in smooth test problems while accurately capturing discontinuities. In MAGNETised Tolman--Oppenheimer--Volkoff (TOV) star tests, \texttt{RAKI} retains $99.2$ per cent of the initial maximum MAGNETic field strength over ${\sim}2$ ms, exhibiting an order of magnitude less MAGNETic field loss than a reference GRMHD code at the same resolution. In BNS merger simulations, fifth-order AFD-WENO-AO reconstruction yields approximately third-order convergence of the gravitational-wave phase in both MAGNETised and unMAGNETised models. The discrete no-monopole constraint is preserved to machine precision without staggered grids, even during BNS mergers with moving refinement regions. These results establish \texttt{RAKI} as a high-order, non-staggered GRMHD framework for accurate modelling of MAGNETic field evolution in neutron star mergers and its implications for multimessenger astrophysics.

[abstract 12 / 70] Yes (score: 6)
arXiv:2610.40092 [pdf, ps, other]

Title: Evolutionary tracks and isochrones of the inverse Hall cascade

Authors: Axel Brandenburg, Vinay Kumar,

Comments: 16 pages, 9 figures, 3 tables, submitted to J. Plasma Phys

Subjects: physics.plasm-ph astro-ph.HE

Created: 2026-10-29; Updated: 2026-10-30; Datestamp: 2026-10-30

Decaying MHD turbulence can exhibit an inverse cascade, which means that the height of the spectrum of MAGNETic energy in the subinertial range increases with time. However, there is evidence for a resistive dependence of the inverse transfer speed. It is unclear whether this is caused by RECONNECTion, which is known to depend on resistivity. Here, we show that in the Hall cascade, where no momentum equation is solved, and the induction term is replaced by what corresponds to the negative Lorentz force in MHD, there is still a resistive dependence of the inverse transfer speed, but no such dependence is found for an analogous numerical RECONNECTion experiment. This suggests that the resistive dependence of the inverse transfer speed is not necessarily related to RECONNECTion.

[abstract 13 / 70] Yes (score: 5)
arXiv:2511.05839 [pdf, ps, other]

Title: Probing Extragalactic Ultralight Axion Dark Matter with Decade-Long Blazar Optical Polarimetry of 1ES 1959+650

Authors: Qiu-Ju Huang, Bao Wang, Jun-Jie Wei, Xue-Feng Wu,

Comments: 13 pages, 8 figures. Published in PRL

Subjects: astro-ph.HE astro-ph.CO hep-ph

Created: 2026-10-29; Updated: 2026-10-30; Datestamp: 2026-10-30

Axions or axion-like particles (ALPs) are well-motivated DARK MATTER (DM) candidates whose coupling to photons induces periodic oscillations in the POLARIZATION angle of astrophysical light. This work reports the first search for such a signature using 10 years of optical polarimetric monitoring of the BLAZAR 1ES~1959+650. No statistically significant periodicity is detected, determined by a Lomb-Scargle periodogram combined with Monte Carlo analysis. Assuming a central DM density in the host galaxy, this null result places tight upper limits on the ALP-photon coupling constant at $g_{aγ}<(1.3\times10^{-13}-6.0\times10^{-10})\,\mathrm{GeV}^{-1}$ across a broad ALP mass range of $m_a \sim (1.4\times10^{-23}-5.2\times10^{-20})\,\mathrm{eV}$. Assuming a soliton-core DM density, we obtain upper limits of $ g_{aγ}< (2.5\times10^{-13}-6.2\times10^{-13})\,\mathrm{GeV}^{-1} $ over the same ALP mass range. Our constraints surpass those from Very Long Baseline Array polarimetry of active galactic JETs and from polarimetric data of the European Pulsar Timing Array, and are competitive with those from long-term Galactic pulsar timing of PSR J0437-4715 over the same ALP mass window. These results establish long-term BLAZAR polarimetry as a competitive and complementary approach for probing axion-like DM on extragalactic scales.

[abstract 14 / 70] Yes (score: 5)
arXiv:2609.26897 [pdf, ps, other]

Title: A Coherent Search for New Galactic Magnetars using FERMI/GBM and follow-up SWIFT/BAT: 7 Candidates and a Large Burst Catalog

Authors: Ariel Perera, Barak Zackay, Tejaswi Venumadhav,

Comments:

Subjects: astro-ph.HE

Created: 2026-10-29; Updated: 2026-10-30; Datestamp: 2026-10-30

Galactic MAGNETars are a rare class of neutron stars with extreme MAGNETic fields, with only about 30 known sources. Their short hard X-ray and soft GAMMA-RAY BURSTs provide an important channel for discovering MAGNETar activity. Wide-field instruments such as the FERMI Gamma-ray Burst Monitor (GBM) are well suited to detecting these bursts, but their broad localization uncertainties make it difficult to associate individual bursts with specific sources. Coded-aperture telescopes, in contrast, provide arcminute-scale localizations but have narrower fields of view. We search for previously unidentified MAGNETars and construct a MAGNETar burst catalog by combining a broad sample of short, soft triggers from our coherent GBM detection pipeline over 2013-2025 with targeted searches of archival SWIFT/BAT images. We develop a statistical association framework that uses BAT detections to localize GBM bursts to arcminute precision, together with a spatio-temporal clustering framework that associates poorly localized bursts with common sources. Together, these methods identify 1720 MAGNETar bursts, of which 1170 are confidently associated with 11 known MAGNETars. The remaining 550 bursts could not be assigned to specific sources. We identify seven candidate new MAGNETars through three complementary discovery channels. The catalog, composed of the associated bursts, extends to the lowest fluences observed by GBM. We also provide spectral and temporal analyses of the catalog. The new candidate sources provide targets for X-ray follow-up that could reveal previously unidentified Galactic MAGNETars. More broadly, this work demonstrates how combining instruments with complementary capabilities can maximize the scientific return of high-energy transient observations.

[abstract 15 / 70] Yes (score: 5)
arXiv:2610.37895 [pdf, ps, other]

Title: Considering Numerical Relativity Surrogate Models for AGN Channel Merger Dynamics

Authors: Shawn Ray, Keefe Mitman, Vera Delfavero, Emily McPike, Jake Postiglione, Harrison E. Cook, Kaila Nathaniel, Nicolas Posner, Barry McKernan, K. E. Saavik Ford, Richard O'Shaughnessy,

Comments: 17 pages, 7 figures, 5 tables

Subjects: astro-ph.HE gr-qc

Created: 2026-10-27; Updated: 2026-10-30; Datestamp: 2026-10-30

Binary BLACK HOLE mergers (BBH) are currently observed by the gravitational-wave detectors LIGO, Virgo, and KAGRA (LVK). A fraction of these mergers are likely to originate in ACTIVE GALACTIC NUCLEi (AGN), but the details of the dynamical processes driving AGN channel mergers remain poorly understood. Monte Carlo For AGN Channel Testing and Simulation (McFACTS) is an open-source, public software used to simulate AGN channel BBH formation and evolution with configurable options for exploring various AGN and Nuclear Star Cluster (NSC) parameter options. Within McFACTS, BBH mergers evolve through gas drag and dynamical interactions, ignoring RELATIVISTIC effects which can influence merger remnant properties. Here we demonstrate in McFACTS the effect of handing off inspiralling BBH to a numerical relativity (NR) surrogate model, which more accurately predicts the masses, spins, and kick velocities of merger remnants. Compared to a simple analytic approach to calculating merger and remnant properties the NR surrogate model is significantly more accurate at predicting remnant spins, which improve $χ_{eff}$ and $χ_{p}$ calculations, and recoil kicks, parameters especially important for higher generation BBH mergers. Our findings show the NR surrogate significantly changes distributions of remnant spins and kick velocities, as well as showing that alternative methods should be used cautiously in future studies. We also outline some simple models which are computationally efficient and can reproduce much of the NR surrogate model results.

[abstract 16 / 70] Yes (score: 5)
arXiv:2610.39253 [pdf, ps, other]

Title: Insights into the Kinematic Evolution of Filament-Induced Jets: Coupling of Interchange and Flare Reconnection

Authors: Zehao Tang, Xiaoli Yan, Zhike Xue, Jincheng Wang, Zhe Xu, Yadan Duan,

Comments: 10 pages, 5 figures

Subjects: astro-ph.SR

Created: 2026-10-29; Updated: 2026-10-30; Datestamp: 2026-10-30

Jets are ubiquitous eruptive activities in the solar atmosphere, playing an important role in mass transport, atmospheric heating, and energy supply. However, the triggering mechanism remains elusive. To reveal the fine process of JET evolution, we study a JET associated with a B-class flare that involves in two distinct stages. Analyzing the complete evolution of a solar JET captured by the Solar Dynamics Observatory (SDO), we clearly identify its dual-stage kinematics, evolving from interchange to flare RECONNECTion. This dual-stage JET is characterized by distinct dual-stage signatures in MAGNETic morphology, H$α$ profile, JET speed, JET height, X-ray flux, loop-top source, and temperature. These differences are naturally unified by a physical picture coupling interchange and flare RECONNECTion, offering new insights into understanding of the physical process of filament-induced JETs.

[abstract 17 / 70] Yes (score: 5)
arXiv:2610.39603 [pdf, ps, other]

Title: The Peculiar Astrometric Behaviour and Radio Structure of the Quasar 1524-136 Revealed with Very Long Baseline Interferometry

Authors: Angelina Osetrova, Sándor Frey, Oleg Titov, Alexey Melnikov, Panna Gelle,

Comments: 22 pages, 5 figures, accepted for publication in the journal Symmetry

Subjects: astro-ph.GA

Created: 2026-10-29; Updated: 2026-10-30; Datestamp: 2026-10-30

According to astrometric very long baseline interferometry (VLBI) observations accurate to sub-milliarcsecond levels, the radio QUASAR 1524-136 (J1526-1351) exhibited an exceptionally large shift, more than 0.1", between the 1990s and 2010s. This luminous QUASAR is known for its extended (~0.4"), highly asymmetric and non-collinear JET structure. Here we analyse historical VLBI astrometric and imaging data, as well as Gaia optical astrometric information, to find the cause of the sudden apparent change in the position. At the X band (~8.4 GHz frequency), where radio positions are conventionally measured, the core region brightened substantially relative to the hotspot at the end of the northern JET. As a result, the brightness peak shifted from the hotspot to the core, causing the VLBI position to shift accordingly. Similar changes could affect the astrometric positions of other radio sources. A better understanding of the astrophysical reasons behind them is important for maintaining the stability of the VLBI-based celestial reference frame.

[abstract 18 / 70] Yes (score: 4)
arXiv:2507.22006 [pdf, ps, other]

Title: Probing Axion-Photon Mixing with High-Resolution X-ray Spectroscopy

Authors: Yu Zhou, Jiejia Liu, Volodymyr Takhistov, Kazuhisa Mitsuda,

Comments: 16 pages, 10 figures

Subjects: astro-ph.HE astro-ph.CO hep-ph

Created: 2026-10-29; Updated: 2026-10-30; Datestamp: 2026-10-30

Axion-like particles (ALPs) provide a compelling avenue for exploring physics beyond the Standard Model. In astrophysical MAGNETized plasmas an ALP-photon coupling $g_{aγ}$ induces energy-dependent oscillations in the photon survival probability that imprint modulations on emission spectra. X-ray observations of bright spectrally-smooth sources can provide particularly sensitive probes of ultralight ALPs with masses $m_a \lesssim 10^{-11}$ eV due to long propagation distances, strong MAGNETic fields and high photon statistics. We present a comprehensive forecast of ALP-photon conversion in three representative systems: (i) background ACTIVE GALACTIC NUCLEi (AGNs) observed through foreground intracluster MAGNETic fields, (ii) central AGNs within their host cluster halos and (iii) Galactic X-ray binaries viewed through the Milky Way field. Using detailed simulations we assess the prospective sensitivity of high-resolution X-ray missions including XRISM, Athena, and Arcus. For typical MAGNETic field configurations a 320 ks XRISM observation or an 8 ks Athena observation of the Perseus Cluster AGN NGC 1275 can reach down to $g_{aγ} \sim 5 \times 10^{-13}$ GeV$^{-1}$ at $m_a \lesssim 10^{-12}$ eV, surpassing the current best limit. We quantify the impact of MAGNETic field modeling, photon statistics, and spectral binning strategies. Our results demonstrate the scientific potential of future X-ray observatories to probe photon-ALP coupling in previously inaccessible parameter space, offering a powerful window into physics beyond the Standard Model.

[abstract 19 / 70] Yes (score: 4)
arXiv:2610.38061 [pdf, ps, other]

Title: Cosmic rays in galaxy halos I: the circumgalactic transport rate and a dynamically significant cosmic-ray reservoir

Authors: Roland M. Crocker, Mark R. Krumholz,

Comments: 18 pages of main text with 10 figures; 2 appendices. Constructive community feedback welcomed in advance of submission

Subjects: astro-ph.HE astro-ph.CO astro-ph.GA

Created: 2026-10-27; Updated: 2026-10-30; Datestamp: 2026-10-30

FERMI-LAT observations imply that most of the COSMIC RAYs (CRs) produced in normal star-forming galaxies escape from the discs where they are accelerated into the circumgalactic medium (CGM), but the subsequent evolution of those escaping CRs is unclear. Here we construct a simple semi-analytic model for their transport and loss, which we constrain by confronting the model with a series of observations: limits on CR energy densities in the outer Milky Way from FERMI-LAT, the isotropic gamma-ray background (IGRB), stacked CGM X-ray emission from eROSITA, and the requirement that the accumulated pressure of CRs in galaxy CGMs not be so large as to render them unstable. We show that these constraints can be jointly satisfied in only two scenarios: one where CRs diffuse quickly through the CGM and freely escape beyond it into the IGM, and another where the CR diffusion time out of halos is of order the Hubble time. In the latter scenario CRs accelerated by STAR FORMATION naturally explain both the IGRB and the heat input required to maintain the temperature of the CGM against X-ray cooling, and their relatively slow transport means that roughly half of the CR energy injected into the CGM of an $L_\star$ halo over its star-formation history remains there at $z \simeq 0$. This makes CR pressure dynamically significant, and also means that a non-negligible part of the IGRB is produced by CRs in the Milky Way's own halo. We argue that this latter scenario is the more likely one, as it avoids the need to posit a second source for the IGRB that is coincidentally very close in both power and spectral shape to the contribution from star-forming discs.

[abstract 20 / 70] Yes (score: 4)
arXiv:2610.38317 [pdf, ps, other]

Title: Numerical Simulations of the interaction between winds from tidal disruption event and supermassive BLACK HOLE circumnuclear medium

Authors: De-Fu Bu, Yu-Heng Sheng, Liang Chen, Guo-Bin Mou, Hao-Jie Xia, Xiao-Hong Yang,

Comments: 25 pages, 15 figures, accepted by APJ

Subjects: astro-ph.HE astro-ph.GA

Created: 2026-10-28; Updated: 2026-10-30; Datestamp: 2026-10-30

The interaction between winds from tidal disruption event (TDE) and the circumnuclear medium (CNM) around supermassive BLACK HOLEs is believed to contribute to the radio emission of non-JETted TDEs. This model has been studied both analytically and numerically. In previous works, the properties of wind are usually set to be angle-independent. It is not clear to what extent the results deviate from those in the case where TDE wind properties are angle-dependent. We perform numerical simulations to investigate the effects of the angular distribution of wind properties on the radio light curve in the wind-CNM interaction model. We find that given that the wind mass and kinetic energy fixed, the radio light curve in the optically thin waveband significantly depends on the angle-dependence of wind properties. Even when the swept-up CNM mass is still less than the wind mass, a slight deceleration can affect the light curve. Changing the angular dependence of the wind properties causes the deceleration to vary across angles. Consequently, the final light curve--the time evolution of radiation integrated over all angles--would differ significantly from that predicted in models with a spatially uniform wind injection. This can result in a slower rise or a faster decline (depending on the CNM profile) than the analytical prediction, and can even turn the rise phase into a long-lasting plateau. Therefore, it is essential to carefully take into account the angular dependence of wind properties to study the wind-CNM interaction.

[abstract 21 / 70] Yes (score: 4)
arXiv:2610.39130 [pdf, ps, other]

Title: Harmonic brightness oscillations point to MAGNETar giant flares in rare short GAMMA-RAY BURSTs

Authors: Run-Chao Chen, Ore Gottlieb, Bin-Bin Zhang, Yuri Levin, Dong Lai, Jun Yang, Yi-Han Iris Yin, Suo-Ning Wang,

Comments: 57 pages, 9 figures; Authors' version of the article published in Science Advances, available at https://www.science.org/doi/abs/10.1126/sciadv.aee6388

Subjects: astro-ph.HE

Created: 2026-10-29; Updated: 2026-10-30; Datestamp: 2026-10-30

Kilohertz quasi-periodic oscillations (QPOs) have been observed in a few rare GAMMA-RAY BURSTs (GRBs), but their physical origin remains uncertain. We reanalyze the two short GRBs with reported kilohertz QPOs, GRB 910711 and GRB 200415A, and find evidence for possible harmonic-like organization around a characteristic frequency scale near 360 hertz. The similar harmonic-like pattern in GRB 910711 and in the confirmed MAGNETar giant flare (MGF) event GRB 200415A, including features extending above 4 kilohertz, points to timing phenomenology on frequency scales relevant to MAGNETar oscillation modes. The temporal and spectral similarities between the two events and the difficulty of explaining these features in merger-driven scenarios favor an MGF-like interpretation of GRB 910711. This timing phenomenology may therefore provide an additional observational handle, complementary to spectral, temporal, and localization information, for distinguishing rare MGF-like transients from merger-driven GRBs.

[abstract 22 / 70] Yes (score: 4)
arXiv:2610.39801 [pdf, ps, other]

Title: The first mass peak of merging BLACK HOLEs from core binding energies and JET-driven explosions

Authors: Nikki Yat Ning Wang, Dmitry Shishkin, Noam Soker,

Comments: Will submit to PASP in two days to allow for comments; 11 pages, 5 figures

Subjects: astro-ph.HE astro-ph.SR

Created: 2026-10-29; Updated: 2026-10-30; Datestamp: 2026-10-30

We show that the jittering-JETs explosion mechanism (JJEM) can qualitatively reproduce the shape of the BLACK HOLE (BH) mass distribution observed by LIGO-Virgo-KAGRA and quantitatively reproduce the peak around $M_{p1} \simeq 10 M_\odot$. To show this, we construct a toy model that captures the JJEM physics that explodes all massive stars, even when BHs form. According to the JJEM, BHs form when the star's binding energy is large, implying a massive progenitor with initial mass $M_i \gtrsim 25 M_\odot$, and when JETs are launched along a fixed axis, implying a rapidly rotating pre-collapse stellar core. In this case, the JETs are launched along the core's angular momentum and are inefficient at removing mass near the equatorial plane; when the stellar binding energy is large, a large fraction of the equatorial mass is accreted to form the BH. The toy model includes two parameters: the threshold binding energy in the core for BH formation and the JET opening angle along the poles. Although our finding is encouraging for the JJEM, future hydrodynamical simulations must determine the exact condition for BH formation in the JJEM and the BH mass.

[abstract 23 / 70] (score: 3)
arXiv:2209.03836 [pdf, ps, other]

Title: Self-force in hyperbolic BLACK HOLE encounters

Authors: Oliver Long,

Comments: PhD Thesis. 139 pages, 37 figures

Subjects: gr-qc astro-ph.HE

Created: 2026-10-29; Updated: 2026-10-30; Datestamp: 2026-10-30

Self-force methods can be applied in calculations of the scatter angle in two-body hyperbolic encounters, working order by order in the mass ratio (assumed small) but with no recourse to a weak-field approximation. This, in turn, can inform ongoing efforts to construct an accurate description of the general-RELATIVISTIC binary dynamics via an effective-one-body description or other approaches. Existing self-force methods are to a large extent specialised to bound, inspiral orbits. Here we derive the first-order conservative self-force correction to the scattering angle, show its agreement with recent post-Minkowsian results, and develop a technique for (numerical) self-force calculations that can efficiently tackle scatter orbits. In the method, the metric perturbation is reconstructed from a Hertz potential that satisfies (mode-by-mode) a certain inhomogeneous version of the Teukolsky equation. The crucial ingredient in this formulation are certain jump conditions that the (multipole modes of the) Hertz potential must satisfy along the worldline of the small body's orbit. We present a closed-form expression for these jumps, for an arbitrary geodesic orbit in Schwarzschild spacetime. To begin developing the numerical infrastructure, a scalar-field evolution code on a Schwarzschild background (in 1+1D) is developed. Following this, results for the conservative scalar self-force corrections to the scatter angle are calculated. We continue by constructing a Teukolsky evolution code on a Schwarzschild background. This produces numerically unstable solutions due to unphysical homogeneous solutions of the Teukolsky equation at the horizon and null infinity being seeded by numerical error. This can be resolved by a change of variables to a Regge-Wheeler-like field. We then present a full numerical implementation of this method for circular and scatter orbits in Schwarzschild.

[abstract 24 / 70] (score: 3)
arXiv:2502.05048 [pdf, ps, other]

Title: A prevalent population of normal-mass central BLACK HOLEs in high-redshift massive galaxies

Authors: Junyao Li, Yue Shen, Ming-Yang Zhuang,

Comments: 14 pages, 6 figures

Subjects: astro-ph.GA

Created: 2026-10-28; Updated: 2026-10-30; Datestamp: 2026-10-30

Understanding the co-evolution of supermassive BLACK HOLEs (SMBHs) and their host galaxies is crucial for explaining how feedback from accreting BLACK HOLEs regulates STAR FORMATION and shapes the growth of galaxies across cosmic time. However, measurements of this co-evolution in the early Universe, as traced by the BLACK HOLE mass - stellar mass relation ($M_{\rm BH} - M_\star$), are subject to strong selection biases: SMBHs that are overly luminous and massive relative to their hosts are preferentially detected, particularly in the more abundant low-mass galaxies. To mitigate these biases, we conduct a systematic search for broad-line ACTIVE GALACTIC NUCLEi (AGN) in 117 spectroscopically confirmed massive galaxies at $z\sim3-5$, using deep JWST imaging and spectroscopic surveys conducted to date. We identify 20 moderate-luminosity AGNs with a mean $M_{\rm BH}/M_\star$ of $\sim0.1\%$, consistent with the local value. By reconstructing their mass ratios back to $z\sim6$, we infer that a substantial population of SMBHs with normal mass ratios was already in place within the first billion years of cosmic history, but has been largely overlooked by existing surveys. Together with the overmassive BLACK HOLEs reported in previous studies, our findings suggest diverse pathways for SMBH formation and growth in the early Universe. In addition, we find comparable $M_{\rm BH}/M_\star$ ratios in star-forming and quiescent host galaxies, suggesting that the formation of massive quiescent galaxies does not necessarily require an overmassive BLACK HOLE, contrary to common theoretical expectations.

[abstract 25 / 70] (score: 3)
arXiv:2601.11780 [pdf, ps, other]

Title: Observation of a cross-section enhancement near the $t\bar{t}$ production threshold in $\sqrt{s}=13$ TeV $pp$ collisions with the ATLAS detector

Authors: ATLAS Collaboration,

Comments: 64 pages in total, author list starting page 47, 12 figures, 4 tables, published at Reports on Progress in Physics. All figures including auxiliary figures are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/TOPQ-2025-11/

Subjects: hep-ex

Created: 2026-10-29; Updated: 2026-10-30; Datestamp: 2026-10-30

A measurement of $t\bar{t}$ production is presented in the invariant-mass region near the pair production threshold, $m_{t\bar{t}} \sim 345$ GeV, in final states with two charged leptons and multiple JETs. The measurement is based on $140\,\mathrm{fb}^{-1}$ of proton-proton collision data collected at $\sqrt{s} = 13$ TeV with the ATLAS detector at the Large Hadron Collider. The data are compared to two models of $t\bar{t}$ production: a baseline model including only perturbative QCD predictions for the hard process at approximate next-to-next-to leading order accuracy in the strong coupling, and an extended model that, in addition, incorporates non-RELATIVISTIC QCD simulations that also include the formation of colour-singlet quasi-bound-states near the $t\bar{t}$ threshold. The agreement between the data and the models is quantified via a profile-likelihood fit to the reconstructed $m_{t\bar{t}}$ distributions, in bins of two angular observables sensitive to spin-correlations in the $t\bar{t}$ system. An excess of events is observed over the baseline perturbative QCD prediction, with an observed significance over $8$ standard deviations. This excess is consistent with the formation of colour-singlet and spin-singlet $S$-wave quasi-bound $t\bar{t}$ states, as predicted by non-RELATIVISTIC QCD, and corresponds to an observed cross-section of $9.3^{+1.4}_{-1.3}$ pb.

[abstract 26 / 70] (score: 3)
arXiv:2607.21719 [pdf, ps, other]

Title: Outflows in a super-Eddington QUASAR drive clumpy circumgalactic medium and extended H$α$ nebulae at $z \gtrsim 6$

Authors: Lucas Tortora, Tiago Costa, Debora Sijacki, Jake S. Bennett,

Comments: 26 pages, 15 figures, accepted to MNRAS

Subjects: astro-ph.GA

Created: 2026-10-29; Updated: 2026-10-30; Datestamp: 2026-10-30

The discovery of gargantuan BLACK HOLEs with masses exceeding a billion solar masses at $z\gtrsim6$ suggests rapid BLACK HOLE growth and significant energy input into their host galaxies in the early Universe. With JWST probing previously unseen phases of the interstellar (ISM) and circumgalactic (CGM) medium around $z > 6$ QUASARs, detailed theoretical studies can now be directly confronted with observations. We use zoom-in simulations of a massive protocluster at $z\sim6$, employing both the fiducial FABLE galaxy formation model and modifications that allow earlier BLACK HOLE seeding and mildly super-Eddington accretion. The central QUASAR remains Compton-thick throughout most of its evolution, with the obscuration arising from the ISM of its compact host galaxy. The onset of sufficiently strong QUASAR feedback drives a 'blow-out' episode, clearing out escape channels for ionizing radiation and leaving the central engine unobscured. This leads to a complete transformation of the CGM, whereby powerful, metal-enriched outflows produce a population of cold, fast, neutral clumps, significantly increasing the covering fraction of neutral hydrogen in the host halo. Radiative transfer calculations performed with a new ray-tracing code show that the CGM responds to QUASAR activity through the formation of H$α$ nebulae, whose size and luminosity increase with the strength of QUASAR feedback and decrease with obscuration level. Enhanced early BLACK HOLE growth thus fundamentally reshapes the ISM and CGM of $z\sim6$ QUASARs, leaving clear observable signatures in their obscuration, neutral hydrogen distribution, and extended H$α$ emission.

[abstract 27 / 70] (score: 3)
arXiv:2610.37876 [pdf, ps, other]

Title: No Significant Excess in Typical Variability in CLAS+ Changing-Look AGN Candidates in Rubin DP2

Authors: Lilianne Nakazono,

Comments:

Subjects: astro-ph.GA

Created: 2026-10-27; Updated: 2026-10-30; Datestamp: 2026-10-30

Rubin Data Preview 2 (DP2) samples the CLAS+ changing-look AGN (CLAGN) candidates $\sim1,000-9,000$ days after their comparison epochs, so it can test whether these objects retain enhanced short-term optical variability after their spectral transitions. Comparing peak-to-peak amplitude in magnitudes against a photometrically quiescent QUASAR control, one band at a time, we do not detect a significant median-amplitude excess for any state (turn-on, turn-off, intermediate) in either of two bands, nor a different in the median $\,|\,Δ\text{mag}\,|\,$ as function of time lag. The $r$-band CLAS+ amplitude distributions are wider than the control's, with the intermediate state formally significant after multiple-comparison correction. This could hint for a high-amplitude subpopulation.

[abstract 28 / 70] (score: 3)
arXiv:2610.38280 [pdf, ps, other]

Title: Machine Learning Based Classification of Type 1 Active Galactic Nuclei

Authors: Jie Li, Xu-Liang Fan,

Comments: 14 Figures, 3 tables, accepted for publication in A&A

Subjects: astro-ph.CO

Created: 2026-10-28; Updated: 2026-10-30; Datestamp: 2026-10-30

Aims. We aim to provide a machine learning based method to distinguish type 1 QUASARs and type 1 Seyfert galaxies based on photometric data, which could be applied to large all-sky surveys. The method can also be used to obtain relatively complete samples of Seyfert galaxy candidates when broad-line AGNs have been selected. Results. The results of PCA show that QUASARs and Seyfert galaxies are partial distinguishable. The supervised classifier based on random forest (RF) achieves good performances for type 1 QUASARs with a F1 score of 0.967. The performance for classifying Seyfert galaxies is worse, with a F1 score of 0.791. Increasing the classification threshold can help to derive a sample of Seyfert galaxies with high purity. The classifier are then applied to the cross-matched sample with DESI DR1. When compared with the results of spectroscopic classification, QUASARs also show high precision and recall. For Seyfert galaxies identified by RF classifier, there are plenty of less luminous sources who are classified as QUASARs by spectroscopic method. If they are regarded as Seyfert galaxies, our classifier also performs well to predict Seyfert galaxies. Both the median SEDs and the fraction of Seyfert galaxies derived by our classifier are similar with those for the training sample, while the fraction of Seyfert galaxies for spectroscopic classification are lower at all redshift. These results indicate that our classifier can recover the features of Seyfert galaxies, at least those similar to the Seyfert galaxies in the training sample.

[abstract 29 / 70] (score: 3)
arXiv:2610.38419 [pdf, ps, other]

Title: The Ubiquity of White-Light Flares on the Sun

Authors: Shuanghong Li, Yongliang Song, Kun Wang, Mei Zhang, Xianyong Bai, Xiao Yang,

Comments: Submitted. Comments are welcome!

Subjects: astro-ph.SR

Created: 2026-10-28; Updated: 2026-10-30; Datestamp: 2026-10-30

White-light flares (WLFs) have long been considered rare on the Sun, as most MAGNETic RECONNECTions occur in the corona, making it difficult to transport sufficient energy downward to heat the very low layers for WL continuum emission. However, it is also argued that WL continuum emission is a common feature of all flares, and the rare detection of them is largely due to the limited sensitivity and resolution of telescopes. Recently, we developed a new method to identify WLFs, which exhibits extraordinary detection capability. Combined with SDO/HMI's over 15 years of continuous photospheric observations, it provides us an unprecedented opportunity to address the long-standing debate about WLF ubiquity. A total of 1951 flares (547 B-class, 1316 C-class, and 88 M-class) from 769 low-activity active regions (ARs; flare number $<$ 10) observed during January 2011 - May 2025 are investigated. Among these, 1012 are identified as WLFs, giving an overall occurrence rate of 51.9\%. The occurrence rates for B-, C-, and M-class flares are 36.9\%, 56.9\%, and 85.2\%, respectively, showing a clear increase with flare class. The occurrence rate is also highly correlated with the AR's sunspot number. For the first time, we find that WL continuum radiation is widely present even among B-class flares. Different WLFs contain varying numbers of WL kernels, which exhibit distinct properties, evolutionary behaviors and different relationships with GOES soft X-ray flux and its time derivative. These results strongly suggest that WLFs are a common phenomenon on the Sun.

[abstract 30 / 70] (score: 3)
arXiv:2610.39181 [pdf, ps, other]

Title: Gravitational lensing of gravitational waves by a Kerr BLACK HOLE

Authors: Jian-hua He,

Comments: 26 pages, 5 figures

Subjects: gr-qc astro-ph.HE

Created: 2026-10-29; Updated: 2026-10-30; Datestamp: 2026-10-30

We simulate the gravitational lensing of gravitational waves (GWs) by a Kerr BLACK HOLE using a $(1+1)$-dimensional time-domain mode-sum approach. To enable efficient explicit time evolution, we implement a localized hyperboloidal foliation combined with a static field redefinition, ensuring bounded characteristic speeds across an extended, uniform tortoise-coordinate grid. Incident GW initial data are constructed by projecting a plane-wave Weyl tensor onto the Kinnersley tetrad. Through local spin-dyad rotations and Wigner $D$-matrix transformations, our framework accommodates both idealized wave packets and realistic binary coalescence signals at arbitrary incidence and POLARIZATION angles. To accurately resolve the lensed waveforms, we evolve over $68,000$ coupled $(j,m)$ modes. Our results reveal that a Kerr BLACK HOLE acts as a diffraction-limited thick lens, focusing GWs into a forward beam. For idealized wave packets, the primary prompt pulse exhibits a spin-independent transverse Gaussian profile, whereas the subsequent lensing coda is sensitive to the BLACK HOLE's spin. For binary coalescence signals, strong-field lensing substantially modifies the post-merger ringdown. However, the lensed inspiral and merger phases in Kerr and Schwarzschild backgrounds are virtually identical, yielding waveform mismatches below $2.2\times10^{-5}$ across various inclinations and POLARIZATIONs. These findings demonstrate that non-spinning Schwarzschild models provide an accurate and computationally economical surrogate to search for strong-field lensing signatures with current ground-based detectors.

[abstract 31 / 70] (score: 3)
arXiv:2610.39384 [pdf, ps, other]

Title: The Disk Awakens: IXPE's Sequel Observation of GS 1354-64 Suggests Changing-Look Behavior in the Steep-Power-Law State

Authors: Swati Ravi, James F. Steiner, Megan Masterson, Lorenzo Marra, Philip Kaaret, Alexandra Veledina, Michal Dovciak, Adam Ingram, Fiamma Capitanio, Sudeb Ranjan Datta, Elise Egron, Javier A. Garcia, Ole Koenig, Honghui Liu, Herman L. Marshall, Guglielmo Mastroserio, Romana Mikusincova, Joey Neilsen, Edward J. R. Nathan, P. -O. Petrucci, Jakub Podgorny, Jiri Svoboda, Yuexin Zhang,

Comments: 23 pages, 10 figures, Submitted to ApJ

Subjects: astro-ph.HE

Created: 2026-10-29; Updated: 2026-10-30; Datestamp: 2026-10-30

After decades of only failed transitions, the BLACK HOLE X-ray binary GS 1354-64 has undergone a complete outburst again. We present its first X-ray polarimetric investigation in the fading steep-power-law (SPL) state, following an earlier intermediate-state IXPE campaign during the same outburst. The 2-8 keV emission has a POLARIZATION degree (PD) of 2.3 +/- 0.2% and POLARIZATION angle (PA) of 5 +/- 3 degrees. Compared with the intermediate state, where PD=3.9 +0.3/-0.2% and PA=-2 +/-2 degrees, the broadband PD is lower while the PA remains consistent. The intermediate-state type-C quasi-periodic oscillation state has also disappeared, marking a major reconfiguration of the accretion flow. Assuming a distance of 7 kpc, the observed the intensity drop from 2.5% to 1.6% of the Eddington luminosity over 10.2 days is punctuated by several broad hour-to-day-scale troughs, tracing two distinct tracks in hardness-intensity space. Simultaneous spectroscopy shows the troughs' spectra contains a cooler disk with smaller apparent normalization, while no change in the Compton component's photon index or normalization is required between tracks. The model-independent analysis identifies a steeper increase in PD with energy outside the troughs, yielding G_E=1.5 +/- 0.2%/keV, compared with G_E=0.7 +0.3/-0.5%/keV during the troughs. Their duration and spectropolarimetric morphology distinguish the troughs from traditional short absorption dips seen in X-ray binaries, providing a possible stellar-mass analog of the recurrent accretion changes that drive "changing-look" behavior in supermassive BLACK HOLE systems.

[abstract 32 / 70] (score: 3)
arXiv:2610.39449 [pdf, ps, other]

Title: Cosmic birefringence tomography with RADIO GALAXies I: Testing birefringence solutions to the CMB-BAO tension

Authors: Toshiya Namikawa, Fumihiro Naokawa, Richard Battye, Salvatore Samuele Sirletti,

Comments: 10 pages, 8 figures

Subjects: astro-ph.CO

Created: 2026-10-29; Updated: 2026-10-30; Datestamp: 2026-10-30

We present an independent test of cosmic birefringence induced by axionlike particles (ALPs) at low redshift using RADIO GALAXies. We focus on models that can alleviate the mild tension between recent baryon acoustic oscillation (BAO) measurements and observations of the cosmic microwave background (CMB). This tension can be explained by a large cosmic birefringence rotation angle generated during the reionization epoch. Such a large rotation can arise if the recent isotropic cosmic birefringence measurements are subject to an $nπ$ phase ambiguity, with $n\in\mathbb{Z}$, or if cold DARK MATTER injects energy into ALPs. We constrain these two scenarios by fitting the cosmic birefringence angles estimated from the JET morphologies and POLARIZATION angles of RADIO GALAXies obtained by Battye, Jackson & Browne (2026). For the $nπ$ model, the radio-galaxy data exclude $|n|\geq 1$ at more than $2σ$ for $\log_{10}(m_ϕ/{\rm eV})\lesssim -30.7$. For the energy injection model, the data are consistent with no energy injection, but with a slight relative preference for a nonzero energy injection compared to the no-injection case. Since our samples are limited to $\sim 3000$ and there could still be several astrophysical uncertainties and statistical fluctuations, further exploration of tomographic cosmic birefringence using a large number of low-redshift RADIO GALAXies is important for independent tests of cosmic birefringence.

[abstract 33 / 70] (score: 3)
arXiv:2610.39692 [pdf, ps, other]

Title: Feeding or Fleeing: The Impact of Enhanced Early Black Hole Growth on Circumgalactic Clumps at $z > 6$

Authors: Floor van Donkelaar, Lucas Tortora, Debora Sijacki,

Comments: Comments and suggestions welcome prior to submission to MNRAS

Subjects: astro-ph.GA astro-ph.HE

Created: 2026-10-29; Updated: 2026-10-30; Datestamp: 2026-10-30

The circumgalactic medium (CGM) of massive high-redshift galaxies contains inflowing filamentary gas, recycled material, and feedback-driven outflows. We investigate the formation and evolution of dense CGM clumps in two cosmological zoom-in simulations of the same massive halo at $z > 6$: the fiducial Fable model and the modified Fable-SE model, which includes enhanced early BLACK HOLE growth through mild super-Eddington accretion. We identify dense gas clumps in the CGM and follow their gas properties, stellar content, and radial evolution across cosmic time. At the resolution probed here, the two simulations show broadly similar distributions of clump gas mass, gas size and associated stellar mass. Instead, the clump populations differ mainly in their abundance, metallicity, and radial evolution. Fable-SE produces substantially more metal-enriched clumps, including an outward-moving population during the strong AGN-driven blow-out phase at $z \lesssim 7$. These systems are associated with disturbed HI-rich gas and relatively high gas densities, linking the increased prevalence of dense, metal-enriched CGM structures in Fable-SE to its stronger AGN-driven blow-out phase. Although inward migration dominates overall, Fable-SE also contains an outward-moving clump population during the blow-out phase, with some clumps moving beyond the virial radius. Our results therefore indicate that the distribution of dense CGM clumps around massive high-redshift galaxies reflects both filamentary accretion and feedback-driven CGM evolution, with strong early AGN activity associated with the outward migration of dense, metal-enriched gas structures containing relatively cool gas.

[abstract 34 / 70] (score: 3)
arXiv:2610.39862 [pdf, ps, other]

Title: Tidal disruption or plunge: the role of neutron star internal structure in BLACK HOLE-neutron star mergers

Authors: Yatharth Chaurasiya, Ritam Mallick,

Comments: 15 pages, 6 figures

Subjects: astro-ph.HE

Created: 2026-10-29; Updated: 2026-10-30; Datestamp: 2026-10-30

The outcome of BLACK HOLE--neutron star (BHNS) mergers is studied using a general-RELATIVISTIC mass-shedding condition in the Kerr spacetime, which determines the tidal-disruption radius from the mass ratio, the BLACK HOLE (BH) spin, the neutron star (NS) compactness, and the ratio of central to average density, $η=\frac{ρ_{c}}{\barρ}$. Comparing this radius with the innermost stable circular orbit, we map the boundary between tidal disruption and plunge for two RELATIVISTIC mean-field equations of state (EOSs) and for an ensemble of about $10^4$ agnostic EOSs spanning the current uncertainty in the NS radius. We find that the disruption threshold is set mainly by the compactness, but NSs with the same compactness and different $η$ can have different outcomes. Using the tidal disruption radius, we construct a remnant-mass model calibrated against 70 numerical-relativity simulations, which reproduces the remnant mass with an accuracy comparable to existing fits. Applying the disruption criterion and the remnant model to GW200105, GW200115, and the candidate BHNS event GW230529, we find that GW200105 and GW200115 are consistent with a direct plunge. GW230529 lies close to the disruption threshold and may have undergone marginal disruption, leaving only a low-mass remnant.

[abstract 35 / 70] (score: 3)
arXiv:2610.40024 [pdf, ps, other]

Title: Inverse Gertsenshteǐn-Zel'dovich Effect in Time-Independent ElectroMAGNETic Field

Authors: Rajendra Prasad Bhatt, Rudraksh Verma, R. Prasad, Sudipta Sarkar,

Comments: 17 pages, 3 figures

Subjects: gr-qc astro-ph.HE

Created: 2026-10-29; Updated: 2026-10-30; Datestamp: 2026-10-30

The inverse Gertsenshteǐn-Zel'dovich effect describes the conversion of gravitational waves into electroMAGNETic waves in the presence of a background electroMAGNETic field. This effect has primarily been studied for constant background electroMAGNETic fields. In this work, we develop a general formalism for calculating the components of the electric and MAGNETic fields induced by the passage of a gravitational wave through a spatially varying, time-independent background electroMAGNETic field. The formalism accommodates all six possible POLARIZATION modes of gravitational waves. We illustrate its applicability through several examples, including gravitational waves propagating through constant and spatially varying electroMAGNETic fields. We further investigate the electroMAGNETic signals generated by the passage of gravitational waves through astrophysical MAGNETic fields, particularly those associated with neutron stars and MAGNETars. By connecting gravitational waves and electroMAGNETic waves--two essential messengers of multi-messenger astronomy--the inverse Gertsenshteǐn-Zel'dovich effect offers a promising framework for both gravitational-wave detection and astrophysical observations. The formalism developed here may therefore find applications in the design of high-frequency gravitational-wave detectors and in the investigation of high-energy astrophysical electroMAGNETic signals.

[abstract 36 / 70] (score: 3)
arXiv:2610.40053 [pdf, ps, other]

Title: KM3-230213A: The Highest-Energy Cosmic Neutrino

Authors: Carla Distefano,

Comments: 24 pages, 13 figures, 1 table. Published in Physics and the Cosmos (2026)

Subjects: astro-ph.HE

Created: 2026-10-29; Updated: 2026-10-30; Datestamp: 2026-10-30

High-energy neutrinos provide a unique probe of the most extreme non-thermal processes in the Universe. The detection of the ultra-high-energy neutrino event KM3-230213A by the KM3NeT neutrino telescope, with an inferred parent-neutrino energy of O(10^17 eV), represents a major step forward in neutrino astronomy. In this review, we summarize the main properties of the event and discuss its interpretation within different astrophysical and cosmological scenarios, including ACTIVE GALACTIC NUCLEi, transient sources, and cosmogenic neutrinos, highlighting the role of multi-messenger constraints. Despite extensive follow-up observations, no unambiguous electroMAGNETic counterpart has been identified, and the event remains in tension with the absence of comparable detections in other experiments. This situation leaves open the possibility of more complex source scenarios or contributions from physics beyond the Standard Model. We also discuss the implications for the ultra-high-energy neutrino landscape and the prospects for future observations with next-generation detectors. KM3-230213A provides a unique opportunity to probe particle acceleration and neutrino production at energies far beyond the reach of terrestrial experiments.

[abstract 37 / 70] (score: 2)
arXiv:2105.05630 [pdf, ps, other]

Title: Time-domain metric reconstruction for hyperbolic scattering

Authors: Oliver Long, Leor Barack,

Comments: 28 pages, 11 figures; v3 corrected typo in Eq. (103); v5 corrected typo in Eq. (A12)

Subjects: gr-qc astro-ph.HE

Created: 2026-10-29; Updated: 2026-10-30; Datestamp: 2026-10-30

Self-force methods can be applied in calculations of the scatter angle in two-body hyperbolic encounters, working order by order in the mass ratio (assumed small) but with no recourse to a weak-field approximation. This, in turn, can inform ongoing efforts to construct an accurate model of the general-RELATIVISTIC binary dynamics via an effective-one-body description and other semi-analytical approaches. Existing self-force methods are to a large extent specialised to bound, inspiral orbits. Here we develop a technique for (numerical) self-force calculations that can efficiently tackle scatter orbits. The method is based on a time-domain reconstruction of the metric perturbation from a scalar-like Hertz potential that satisfies the Teukolsky equation, an idea pursued so far only for bound orbits. The crucial ingredient in this formulation are certain jump conditions that (each multipole mode of) the Hertz potential must satisfy along the orbit, in a 1+1-dimensional multipole reduction of the problem. We obtain a closed-form expression for these jumps, for an arbitrary geodesic orbit in Schwarzschild spacetime, and present a full numerical implementation for a scatter orbit. In this paper we focus on method development, and go only as far as calculating the Hertz potential; a calculation of the self-force and its physical effects on the scatter orbit will be the subject of forthcoming work.

[abstract 38 / 70] (score: 2)
arXiv:2501.16258 [pdf, ps, other]

Title: A Possible Mass Ratio and Spin-Orbit Misalignment Correlation for Mergers of Binary Black Holes in Nuclear Star Clusters

Authors: Yubo Su,

Comments: 33 pages, 7 figures, accepted to Universe

Subjects: astro-ph.HE

Created: 2026-10-29; Updated: 2026-10-30; Datestamp: 2026-10-30

Despite a decade's worth of gravitational wave observations, the origin of the binary BLACK HOLE (BBH) mergers detected by the LIGO-Virgo-KAGRA (LVK) collaboration remains an open question. Towards assessing the feasibility and prevalence of the many proposed BBH formation channels, the spin properties of the merging BLACK HOLEs (BHs) hold significant promise, particularly their orientations. Moderate preferential alignment of BH spins with their orbit normals, as well as an apparent anti-correlation between the BBH effective spin parameters $χ_{\rm eff}$ and their mass ratios, would appear to disfavor purely dynamical BBH formation mechanisms, as they lack a preferred orientation to the system. However, alternatives are filled with physical and modeling uncertainties. In this paper, we highlight a dynamical route to easily characterizable spin evolution that results in analytically predictable spin distributions. We show that, when a stellar binary forms a BBH through two phases of stable mass transfer, and the BBH is subsequently driven to merger by the gravitational perturbation of a distant massive object (such as a supermassive BLACK HOLE), the resulting $χ_{\rm eff}$ may be anti-correlated with the binary mass ratio. While the mechanism as proposed only operates in a modest region of parameter space, it also predicts significantly tighter correlations than are seen in the GWTC-4.0 systems. We discuss avenues for future work that may significantly expand the parameter space of our mechanism while still remaining broadly consistent with observations.

[abstract 39 / 70] (score: 2)
arXiv:2507.08213 [pdf, ps, other]

Title: Invariant Reduction for Partial Differential Equations. III: Poisson Brackets

Authors: Kostya Druzhkov,

Comments: J. Geom. Phys. version

Subjects: nlin.SI math.DG

Created: 2026-10-27; Updated: 2026-10-30; Datestamp: 2026-10-30

We establish that local Hamiltonian operators admitted by systems of partial differential equations (PDEs) induce Poisson bivectors on suitable finite-dimensional subsystems describing invariant solutions. This correspondence is governed by the mechanism of invariant reduction, which applies uniformly to point, contact, and higher symmetries. We show that the induced Poisson bivectors relate constants of invariant motion to symmetries of such subsystems. Applying the same reduction mechanism to invariant conservation laws, we further deduce that the corresponding Poisson brackets on the reduced systems agree, up to a global sign, with those of the original systems. The results are illustrated by two examples in which the induced Poisson brackets and constants of invariant motion yield integrability of the reduced systems. The construction is independent of the choice of an $\ell$-normal inclusion of a PDE system into JET spaces, with the corresponding odd cotangent covering being $\ell$-normal.

[abstract 40 / 70] (score: 2)
arXiv:2510.11790 [pdf, ps, other]

Title: False Alarm Rates in Detecting Gravitational Wave Lensing from Astrophysical Coincidences: Insights with Model-Independent Technique GLANCE

Authors: Aniruddha Chakraborty, Suvodip Mukherjee,

Comments: 22 pages, 12 figures (including appendices). Accepted for publication in ApJ

Subjects: gr-qc astro-ph.CO astro-ph.GA astro-ph.HE

Created: 2026-10-29; Updated: 2026-10-30; Datestamp: 2026-10-30

Lensing of gravitational waves (GWs) due to intervening massive astrophysical systems between the source and the observer is an inevitable consequence of the general theory of relativity, which can produce multiple GW events with overlapping sky localization error. However, the confirmed detection of such a unique astrophysical phenomenon is challenging due to several sources of contamination, ranging from detector noise to astrophysical uncertainties. Robust model-independent search techniques that can mitigate noise contamination have been developed in the past. In this study, we explore the astrophysical uncertainty associated with incorrectly classifying a pair of unlensed GW events as a lensed pair and the associated false alarm rate (FAR) depending on the GW source properties. To understand the effect of unlensed astrophysical GW sources in producing false lensing detections, we perform a model-independent test using the pipeline GLANCE on a simulated population of merging binary BLACK HOLEs (BBHs). We find that $\sim$ 0.01\% of the pair of events can be falsely classified as lensed with a lensing threshold signal-to-noise ratio of 1.5, appearing at a time delay between the pair of events of $\sim$ 1000 days or more. We show the FAR distribution for the parameter space of the GW source masses, delay time, and lensing magnification parameter over which the model-independent technique GLANCE can confidently detect lensed GW pair with the current LIGO detector sensitivity. In the future, this technique will be useful in understanding the lensing FAR for next-generation GW detectors, which can observe more GW sources.

[abstract 41 / 70] (score: 2)
arXiv:2512.13957 [pdf, ps, other]

Title: From ASTRID to BRAHMA -- The role of overmassive BLACK HOLEs in little red dots in cosmological simulations

Authors: Patrick LaChance, Aklant Kumar Bhowmick, Rupert A. C. Croft, Tiziana Di Matteo, Yihao Zhou, Fabio Pacucci, Laura Blecha, Paul Torrey, Yueying Ni, Nianyi Chen, Simeon Bird,

Comments: Published in the Open Journal of Astrophysics; 18 pages, 9 figures,

Subjects: astro-ph.GA

Created: 2026-10-29; Updated: 2026-10-30; Datestamp: 2026-10-30

We investigate the origin of Little Red Dots (LRDs) using a realization of the BRAHMA cosmological hydrodynamic simulation that produces overmassive BLACK HOLEs at $z \sim 4\text{-}8$. We generate mock JWST observations by modeling galaxy spectral energy distributions (including dust attenuation) together with AGN emission using cloudy-based templates, and test whether such systems reproduce the observed LRD population. We consider both a standard low-redshift AGN emission model and a gas-enshrouded AGN emission model, in which the AGN is embedded within unresolved dense gas that produces a strong Balmer break, and find that LRDs emerge in significantly larger numbers with the latter model. Assuming that all AGN reside in this gas-enshrouded phase, we recover LRD number densities ($Φ\sim 2 \times 10^{-4}~\mathrm{Mpc}^{-3}$), close to the observed abundance. This implies an effective gas-enshrouded duty cycle approaching unity, which is not predicted by current theoretical models. Current JWST constraints on the high-z BLACK HOLE mass function suggest that this tension may arise from a deficit of low-mass ($M_{\rm BH}\lesssim10^7~M_\odot$) LRDs in BRAHMA. Applying the same gas-enshrouded model to the ASTRID simulation, which lacks overmassive BLACK HOLEs, we find that the LRD abundance remains $\gtrsim2~\rm dex$ below observations. Overall, while the overmassive BLACK HOLEs in this BRAHMA realization substantially enhance the production of LRD-like systems, reproducing the observed LRD abundance requires them to reside in dense gas environments with unrealistically high duty cycles. We therefore conclude that overmassive BLACK HOLEs are unlikely to be the sole origin of the observed JWST LRD population, and may instead account for only a subset of these systems.

[abstract 42 / 70] (score: 2)
arXiv:2602.23983 [pdf, ps, other]

Title: Available Energy and Ground States of Convective Hydrodynamic and HydroMAGNETic Instabilities

Authors: Kaixuan Fan, Yao Zhou,

Comments:

Subjects: physics.plasm-ph

Created: 2026-10-28; Updated: 2026-10-30; Datestamp: 2026-10-30

We propose a method for predicting the nonlinear saturation level of convective instabilities in neutral and MAGNETized fluids. The method combines Gardner's restacking algorithm, which computes the available energy and ground states of collisionless plasmas in phase space, and Lagrangian relaxation, where fluid elements find lower-energy equilibria while preserving local invariants. For the incompressible Rayleigh-Taylor instability, the problem is formally equivalent to Gardner's and the restacking algorithm directly applies in configuration space. To treat compressibility, we follow restacking with Lagrangian relaxation to obtain the ground state, and the results show excellent agreement with direct numerical simulations. Successful extension to the $m=0$ interchange instability in a Z-pinch demonstrates the method's potential as a general framework for estimating the nonlinear extent of convective instabilities, which can facilitate the design and operation of fusion reactors.

[abstract 43 / 70] (score: 2)
arXiv:2604.26763 [pdf, ps, other]

Title: Geodesic torsion of the MAGNETic field line and other predictors of coil non-planarity in QI stellarators

Authors: Andrea Pavone, Sehyun Kwak, Felix Warmer,

Comments:

Subjects: physics.plasm-ph

Created: 2026-10-29; Updated: 2026-10-30; Datestamp: 2026-10-30

Stellarator MAGNETic fields are often realized with non-planar modular coils with their out-of-plane bending being one of the main engineering challenges. We ask whether the non planarity of the fialment can be predicted from the equilibrium alone. We look at a dataset of coils for stellarator equilibira and find that the geodesic torsion of the MAGNETic field line is a strong and robust predictor in a wide range of coil feasibility requirements. We compare the performance of the geodesic torsion against other equilibrium and surface geometry properties and find it to be a superior predictorv hardly replaceable by other quantities we considered in this dataset. The ranking it induces also reproduces the ordering of four published configurations --- precise QA, precise QI at nfp 2 and 3, and W7-X. Our conclusions suggest that geodesic torsion of the MAGNETic field line may be considered as a cheap and robust candidate for a stage-one non-planarity proxy.

[abstract 44 / 70] (score: 2)
arXiv:2605.03239 [pdf, ps, other]

Title: Squid funnels time their elastic recoil to amplify pulsed JETs

Authors: Daehyun Choi, Paras Singh, Ian Bergerson, Minho Kim, Jieun Park, Halley J. Wallace, Kenny Zhang, Sandy Y. Hsieh, Aqua T. Asberry, Theodore A. Uyeno, William F. Gilly, Hyungmin Park, Daeshik Kang, Chandan Bose, Saad Bhamla,

Comments: 49 pages (11 pages main text, 38 pages Supplementary Materials), 3 main figures, 28 supplementary figures, 1 table. Revised version

Subjects: physics.flu-dyn

Created: 2026-10-28; Updated: 2026-10-30; Datestamp: 2026-10-30

Pulsed JETs propel squid across nearly four orders of magnitude in body size. Each pulse leaves through the funnel, a soft nozzle, but whether its compliance acts within a pulse is not known. We tracked chromatophores on two squid species and found that the funnel dilates and recoils, with a repeatable phase lag, while the mantle is still contracting, and that the lag persists after denervation. For inertia-dominated JETs, silicone nozzles, 3D fluid-structure simulations and a reduced-order model agree that the impulse reaches about 4$\times$ the rigid value when the nozzle response time is 0.2 to 0.4 of the JET-acceleration time, a range that overlaps the in vivo timing. The wall stores strain energy during acceleration and returns it during expulsion (akin to an elastic capacitor), which we term "superpropulsion". Synthetic nozzles tuned for superpropulsion launch JETs farther in air, disperse dye faster, and drive a boat faster at a lower cost of transport.

[abstract 45 / 70] (score: 2)
arXiv:2605.08338 [pdf, ps, other]

Title: Revisiting predictions for cosmic-ray antinucleon fluxes from Galactic Dark Matter

Authors: Lorenzo Stefanuto, Mattia Di Mauro, Fiorenza Donato, Nicolao Fornengo, Jordan Koechler, David Maurin,

Comments: 17 pages, 11 figures; v2: minor changes, updated Figure 7

Subjects: hep-ph astro-ph.HE

Created: 2026-10-29; Updated: 2026-10-30; Datestamp: 2026-10-30

The data on cosmic antiprotons have reached an outstanding precision on energies spanning from GeV to hundreds of TeV, thanks to the space-based AMS-02 experiment. The balloon-borne GAPS experiment, which just completed its first Antarctic flight, will address antiproton and antideuteron fluxes well below GeV energies. Antinuclei in COSMIC RAYs, as well as being produced by spallation reactions between cosmic-ray nuclei and the atoms of the interstellar medium, may hide contributions from exotic sources, such as particle DARK MATTER annihilation in the Galaxy. In this paper, we present predictions for cosmic antiproton, antideuteron and antihelium fluxes both from secondary and DARK MATTER origin. We use state-of-the-art production spectra, nuclear coalescence for antinuclei, and Galactic propagation models to derive upper limits on the DARK MATTER annihilation cross-section from AMS-02 antiproton data in different propagation scenarios (BIG and QUAINT). We quantify the impact of future GAPS data, showing that its sensitivity to sub-GV antiprotons could improve the $\langleσv\rangle$ constraints by up to an order of magnitude for light DM ($m_χ \lesssim 50$ GeV). For heavier antinuclei, the detection perspective with existing and upcoming experiments are derived for those scenarios consistent with AMS-02 antiproton flux. The detectability of such signals strongly depends on the experiment, the propagation model, and the hadronization tuning. Our analysis underscores the complementarity of antinuclei channels for indirect DM searches and the critical role of low-energy windows in constraining light DM candidates.

[abstract 46 / 70] (score: 2)
arXiv:2606.04740 [pdf, ps, other]

Title: TDEs on FIRE: Illuminating the Cosmic Evolution of Tidal Disruption Rates

Authors: Rudrani Kar Chowdhury, Lixin Dai, Janet N. Y. Chang, Tsang Keung Chan,

Comments: Accepted for publication in ApJ

Subjects: astro-ph.HE

Created: 2026-10-29; Updated: 2026-10-30; Datestamp: 2026-10-30

Tidal disruption events have been extensively studied in the local universe, but their prevalence at high redshifts remains largely unexplored. Using the FIRE-2 cosmological zoom-in simulations, we compute the per-galaxy tidal disruption rate (TDR) over $z=1-10$, covering BLACK HOLEs from IMBHs to SMBHs. The averaged TDR rises from the early universe, peaks at $\sim 4 \times 10^{-4} \, \text{gal}^{-1} \text{yr}^{-1}$ near $z \sim 2.5$, and declines to $\sim 10^{-5} \, \text{gal}^{-1} \text{yr}^{-1}$ at $z=1$. The TDR correlates strongly with host galaxy STAR FORMATION rate and central stellar density at all redshifts. Qualitatively, the TDR trends with the $M_{\rm BH}$ and $M_{\rm gal}$ persist from high redshift to the local universe, suggesting similar BH-galaxy scaling across cosmic time. Satellite galaxies exhibit comparably high TDRs, with their fractional contribution increasing significantly at high redshifts, highlighting their potential for probing IMBHs and early galaxy assembly. This work demonstrates that cosmological simulations offer a promising avenue for constraining the cosmic evolution of the TDR, paving the way for future comparisons with next-generation observations.

[abstract 47 / 70] (score: 2)
arXiv:2606.27833 [pdf, ps, other]

Title: Collisionless dynamo seeds from phase mixing-induced electron slippage

Authors: István Pusztai, Lise Hanebring, James Juno,

Comments: 3 figures

Subjects: physics.plasm-ph

Created: 2026-10-27; Updated: 2026-10-30; Datestamp: 2026-10-30

Magnetic fields permeating the Universe on the largest astrophysical scales are thought to result from dynamo amplification in weakly collisional turbulence, but the origin of the seed fields remains an open problem of cosmic MAGNETogenesis. We identify a kinetic mechanism for MAGNETic-field generation in initially unMAGNETized, collisionless plasmas, arising from phase-mixing-induced braking of spatially varying electron flows. Using analytical theory, fully kinetic Vlasov simulations, and turbulent scaling arguments, we show that this process generates coherent MAGNETic seed fields on scales far larger than the characteristic kinetic scales of the plasma, with strengths comparable to or exceeding classical Biermann battery estimates. The mechanism requires neither a finite initial MAGNETic field nor misaligned thermodynamic gradients and occurs naturally in electron-ion plasmas.

[abstract 48 / 70] (score: 2)
arXiv:2607.17869 [pdf, ps, other]

Title: Black hole spin-mass correlation and vector resonant relaxation in gaseous star clusters: the origin of GW231123?

Authors: Zacharias Roupas,

Comments:

Subjects: astro-ph.HE astro-ph.GA

Created: 2026-10-29; Updated: 2026-10-30; Datestamp: 2026-10-30

During the formation of a star cluster a spin-mass correlation of stellar BLACK HOLEs is generated as they grow via accretion of the residual gas. Moreover, the BLACK HOLE spin tends to be anti-aligned with its orbital angular momentum in the cluster. We show that GW231123, reported by the LIGO-Virgo-KAGRA (LVK) collaboration, lies on our predicted high-mass, high-spin plateau of the spin-mass correlation with positive Bayesian evidence over the LVK prior. Furthermore, vector resonant relaxation (VRR) equilibrium is favored over the isotropic LVK prior in reproducing the distribution of the relative spin tilt. The joint Bayes factor suggests strong evidence for the favored cluster models. GW231123 is thus consistent with our proposed channel that generates correlated BLACK HOLE masses and spins, and drives the spins' orientations.

[abstract 49 / 70] (score: 2)
arXiv:2607.23742 [pdf, ps, other]

Title: Spectral properties of mesoscale fluctuations in interplanetary coronal mass ejections

Authors: Anna-Sofia Jylhä, Simon Good, Emilia Kilpua,

Comments: 10 pages, 8 figures; accepted for publication in Astronomy & Astrophysics 2026 October 27

Subjects: astro-ph.SR physics.plasm-ph physics.space-ph

Created: 2026-10-28; Updated: 2026-10-30; Datestamp: 2026-10-30

Magnetic fields in interplanetary coronal mass ejections (ICMEs) often display a flux rope structure at large scales and a turbulent cascade of fluctuations at smaller scales. However, the nature of fluctuations at transition scales between the flux rope and turbulence - i.e., at mesoscales - has not been previously examined in detail. Mesoscale fluctuations of the MAGNETic field in 142 ICME intervals with clear flux rope signatures at 1 au have been examined using wavelet power spectra, with "mesoscale" defined here as spacecraft-frame frequencies $10^{-4}\ \text{Hz}

[abstract 50 / 70] (score: 2)
arXiv:2608.16767 [pdf, ps, other]

Title: A posteriori correction of Gaia CRF proper motions using conditional probability and zero-parallax prior

Authors: Valeri V. Makarov,

Comments: Published in PASP 138:104509, October 2026, DOI 10.1088/1538-3873/aea7da

Subjects: astro-ph.GA

Created: 2026-10-29; Updated: 2026-10-30; Datestamp: 2026-10-30

The formal precision of Gaia CRF proper motions, and in principle positions, can be statistically improved by introducing conditional probability based on the zero-parallax prior for these extremely distant sources. The method developed in this study produces statistically conditioned proper-motion estimates under the assumed per-source Gaussian covariance model. It is demonstrated that thus corrected proper motion vectors of 1.2 million CRF objects in Gaia DR3 show a tighter distribution around zero and a general reduction in the rate of outliers by approximately 15\%. A general vector spherical harmonic fit to degree 4 is produced with the corrected data for a filtered subset of CRF QUASARs with redshifts between 1 and 1.5. This application, predicated on the unknown stochastic component of the global parallax field, shows a 3-sigma change in the estimated magnitude of the Galactocentric acceleration of the solar system barycenter, quantifying the sensitivity of this fundamental determination to the proposed conditioning of proper motions.

[abstract 51 / 70] (score: 2)
arXiv:2608.25919 [pdf, ps, other]

Title: HII-CHI-mistry for ACTIVE GALACTIC NUCLEi: optical sulphur abundances without empirical ionisation correction factors

Authors: E. Pérez-Montero, O. L. Dors, I. A. Zinchenko, B. Pérez-D\'ıaz, J. M. V\'ılchez,

Comments: Revised version accepted for publication by the Open Journal of Astrophysics. 14 pages, 10 figures

Subjects: astro-ph.GA

Created: 2026-10-27; Updated: 2026-10-30; Datestamp: 2026-10-30

> The determination of sulphur abundances in ACTIVE GALACTIC NUCLEi (AGN) is uncertain because ionisation correction factors (ICFs) are commonly calibrated for HII regions. We extend the HII-CHI-mistry methodology to derive total S/H in AGN from optical emission lines through comparison with photoionisation models. Tests against Seyfert galaxies with direct-method ionic abundances favour models with alpha_ox=-1.2 and a 98% free-electron stopping criterion. While O/H agrees with previous determinations, HCm yields systematically larger S/H than direct-method analyses using classical ICFs, suggesting that these prescriptions underestimate higher sulphur ionisation stages in AGN. Applied to MaNGA Seyfert and LINER-like regions, the method reveals a common positive S/O-metallicity relation. Seyferts show slightly larger median S/O than star-forming regions at high O/H, while LINERs occupy an intermediate position. These differences become weaker when S/H rather than O/H is used as the metallicity tracer, although Seyferts still tend to populate the upper envelope. Sulphur may therefore provide a robust tracer of gas-phase metallicity, while the differences between Seyferts and LINERs may reflect differences in their ionisation conditions and ionising SEDs.

[abstract 52 / 70] (score: 2)
arXiv:2609.10384 [pdf, ps, other]

Title: Wide Field Localization Using Fixed Modulation Collimators

Authors: Steven E. Boggs,

Comments: 19 pages, 4 figures, accepted for publication in The Astronomical Journal (revised October 28, 2026)

Subjects: astro-ph.IM astro-ph.HE

Created: 2026-10-28; Updated: 2026-10-30; Datestamp: 2026-10-30

Rapid, precise localization of GAMMA-RAY BURSTs (GRBs) requires continuous wide-field imaging at hard X-ray and soft gamma-ray energies. We develop a fixed (non-rotating) modulation-collimator architecture to address this challenge. A bigrid collimator, a pair of aligned, periodic slit grids in front of a simple, non-imaging photon-counting detector, transmits an off-axis source through a triangular fringe pattern whose local angular position, the source phase, is recovered from simultaneous count rates in several grid pairs at fixed relative phase offsets, rather than by mechanically rotating a single grid pair as in the classical rotating modulation collimator. Four-phase demodulation of these count rates robustly cancels detector background and grid leakage without requiring rotation. Because the fringe pattern repeats across the sky, a phase measurement corresponds to many candidate source positions; we resolve this ambiguity over an arbitrarily wide field of view using a cascade of progressively coarser-pitched grid stages, generalizing the two-grid vernier-scale technique originally used to localize Sco X-1. This vernier cascade technique reduces the required photon counts and grid-calibration accuracy required to achieve fine angular resolution over a broad field of view. Generalized to two dimensions with orthogonal cascades, the resulting architecture achieves wide-field localization with no moving parts, no time modulation, and only simple photon-counting detectors, a promising candidate for simple, inexpensive, continuous-monitoring instruments supporting time-domain and multi-messenger astrophysics.

[abstract 53 / 70] (score: 2)
arXiv:2609.17436 [pdf, ps, other]

Title: Spontaneous wandering of the MAGNETic axis in pulsars: 3D MAGNETo-thermal simulations and the imprint on braking indices

Authors: Clara Dehman, Daniele Viganò,

Comments: 22 pages, 12 figures. Accepted for publication in A&A

Subjects: astro-ph.HE

Created: 2026-10-28; Updated: 2026-10-30; Datestamp: 2026-10-30

Braking index measurements of hundreds of pulsars, despite observational caveats, show a clear trend: $n<3$ at early ages, $n>3$ at middle ages, and increasingly large, fluctuating values at larger characteristic ages. Crustal MAGNETic fields in isolated neutron stars evolve through Ohmic dissipation and non-linear Hall redistribution across scales, with additional early-time contributions from the chiral MAGNETic effect and post-burial re-emergence. Initial conditions are usually assumed dipole-dominated, whereas more complex and realistic fields, with energy spread more evenly over a broad range of scales, have not been explored in this context. We assess how the internal dynamics of initially non-trivial fields change the dipolar field strength and obliquity, and how their combined contribution to the braking index $n$, together with that of the alignment, compares with the observed values. To this end we perform long-term 3D MAGNETo-thermal simulations, for configurations ranging from the dipole-dominated case to tangled, small-scale-dominated fields. Small-scale dominated configurations with weak dipolar components show rich dynamics: the dipolar mode is continuously fed by the small scales and may grow or decay depending on the initial spectrum, driving $n<3$ or $n>3$, while the obliquity varies on timescales as short as ${\cal O}$(kyr). These spontaneous changes often dominate the alignment torque and can account for the large values of $n-3$ of either sign observed at characteristic ages $τ_c\gtrsim10^5$ yr, unlike the dipole-dominated models. However, short-term MAGNETospheric fluctuations or superfluid-driven variations of the torque may still be needed to explain the measurements and the structured timing residuals quantitatively. Future work comparing these models with the observed timing properties could fine-tune the most promising initial configurations.

[abstract 54 / 70] (score: 2)
arXiv:2610.02429 [pdf, ps, other]

Title: Extending the Pulsar radio population through Quantum Vacuum Cherenkov Emission

Authors: Tales A. O. Gomes, Sergei V. Bulanov, Jaziel G. Coelho, Martin Jirka, Alexander J. Macleod, J. A. Rueda,

Comments: Submitted in Communications Physics. 8 pages, 2 figures

Subjects: astro-ph.HE

Created: 2026-10-29; Updated: 2026-10-30; Datestamp: 2026-10-30

The presence of some radio pulsars within and below the so-called ``death valley'' in the $P$--$\dot{P}$ diagram challenges the standard pair-cascade models based on curvature radiation (CR) and resonant inverse Compton scattering (RICS) in neutron star polar caps. We show that Cherenkov radiation from the quantum vacuum, a strong-field quantum electrodynamics (QED) phenomenon enabled by vacuum POLARIZATION, constitutes a distinct pair-creation channel within the vacuum gap model. Within this model, the acceleration length scale for Cherenkov photon emission and the subsequent photon mean free path are sufficiently short to ensure rapid conversion into $e^+e^-$ pairs. This process acts as a complementary pair-creation channel, remaining viable even in regimes where classical mechanisms become heavily suppressed. This leads to a new set of death lines in the $P$--$\dot{P}$ diagram that partially overlap with and extend beyond the CR and RICS death valleys, enlarging the viable parameter space for radio-emitting neutron stars. The result provides a physical basis for coherent radio emission from long-period neutron stars previously considered inactive, and offers a new window for testing non-linear QED with next-generation radio facilities such as the Square Kilometre Array.

[abstract 55 / 70] (score: 2)
arXiv:2610.37511 [pdf, ps, other]

Title: Color-Reconnection Effects on the nMPI-Nch Conditional Multiplicity Fluctuations in PYTHIA 8 pp Collisions

Authors: Subir Sarkar, Kalyan Dey,

Comments:

Subjects: hep-ph

Created: 2026-10-28; Updated: 2026-10-30; Datestamp: 2026-10-30

Color RECONNECTion (CR) changes both the mean and the dispersion of charged-particle multiplicity in pp collisions. We study the conditional distribution P(Nch | nMPI = m) at fixed PYTHIA interaction count for sqrt(s) = 2.76, 7, and 13 TeV, using charged particles in |eta| < 0.8 and 0.15 < pT < 20 GeV/c. CR is switched on or off while the remaining tune parameters are held fixed. Enabling CR reduces the conditional mean by a larger fraction than the standard deviation. The absolute width therefore decreases, while the coefficient of variation increases in every retained matched MPI bin. This ordering also holds in independent 13 TeV samples with Monash, A14, and CMS CP5. Comparisons with ALICE mean-transverse-momentum data and simulated activity estimators relate these conditional fluctuations to experimentally accessible final-state observables.

[abstract 56 / 70] (score: 2)
arXiv:2610.37757 [pdf, ps, other]

Title: Seeing Unseen Gravitational Wave Inspirals at the Galactic Center

Authors: Pau Amaro Seoane, Qimin Song, Shao-Dong Zhao, Kostas Tzanavaris, Reinhard Genzel, Frank Eisenhauer, Thomas Ott, Stefan Gillessen, Guillaume Bourdarot, Diogo C. Ribeiro, Matteo Sadun Bordoni, Simran Joharle, Felix Mang, Andreas Burkert, Jorge Cuadra, Diego Calderón, Re'em Sari,

Comments: Accepted for publication ApJ Letters

Subjects: astro-ph.HE astro-ph.GA gr-qc

Created: 2026-10-27; Updated: 2026-10-30; Datestamp: 2026-10-30

The Galactic Center is expected to host a population of extremely large mass-ratio inspirals (X-MRIs) migrating toward the supermassive BLACK HOLE. We propose an observational approach utilizing the secular gravitational torque exerted by X-MRIs on the highly eccentric S-star S301. This approach is intrinsically limited by the stochastic nature of the surrounding stellar-mass BLACK HOLE cusp. As S301 propagates through this granular medium, it experiences discrete gravitational encounters. Standard orbital fitting procedures inherently assume a smooth background potential; applying them to stochastic trajectories averages these discrete velocity discontinuities into a continuous secular drift. This introduces a systematic bias that mimics the X-MRI precession signal, invalidating traditional mass estimation techniques. To resolve this degeneracy, we implement a methodology based on the Wavelet Transform Modulus Maxima method to characterize the local Hölder regularity of the orbital motion. This model isolates the singular discontinuities induced by stellar-mass BLACK HOLE encounters from the continuous torque of the X-MRI distribution, allowing for detection even when instantaneous accelerations are below the instrumental noise threshold. We demonstrate analytically that S301 is highly sensitive to the interior X-MRI population while remaining dynamically decoupled from the secular influence of the exterior cusp. Combining precision astrometry and radial velocity projections, we establish that a minimal population of two X-MRIs is detectable within a five to nine-year timeframe, allowing us to constrain the presence of an unseen orbiter population prior to the launch of space-based gravitational wave detectors.

[abstract 57 / 70] (score: 2)
arXiv:2610.37893 [pdf, ps, other]

Title: The MARTINI platform II. Tracing r-process nucleosynthesis in neutron star mergers with long-lived remnants

Authors: Eleonora Loffredo, Diego Vescovi, Albino Perego, Federico Maria Guercilena, Sergio Cristallo,

Comments: 20 pages, 15 figures

Subjects: astro-ph.HE

Created: 2026-10-27; Updated: 2026-10-30; Datestamp: 2026-10-30

Binary neutron star (BNS) mergers are among the primary sites of the rapid neutron-capture (r-)process. In mergers with long-lived remnants, sustained neutrino irradiation raises the electron fraction of the disc wind ejecta, modifying the resulting nucleosynthesis pattern. Yields from numerical-relativity simulations with accurate neutrino transport are needed to quantify the contribution of BNS mergers to the Galactic production of heavy elements and to interpret kilonova spectra. We present and publicly release tracer trajectories and nucleosynthesis yields for eight BNS mergers forming long-lived neutron star remnants, obtained from general-RELATIVISTIC simulations with M1 neutrino transport, spanning two equations of state (DD2 and SFHo), and a range of total masses and mass ratios. Passive tracer particles following the dynamical and wind ejecta were post-processed with the nuclear reaction network WinNet up to 1 Gyr. The yields and tracer trajectories are available on the MARTINI platform. At 1 day, the production of light and first-peak elements (He, Ni, Sr, and Y) is similar across models and is primarily enhanced by the neutrino-irradiated disc wind. The yields of heavy nuclei vary by more than one order of magnitude, with unequal-mass binaries producing the largest amounts owing to their more neutron-rich ejecta. Our He yields, particularly in the wind, exceed those of recent studies based on an M0 neutrino scheme, consistent with the stronger neutrino irradiation resulting from an M1 scheme. At 1 Gyr, all models reproduce the second and third solar r-process peaks, but differ in the first peak, the lanthanide region, the mass range between the first and second peaks, and the trans-lead region, reflecting the electron fraction distribution of the ejecta and the dynamical and wind contributions. Two equal-mass models provide a close match to the solar pattern.

[abstract 58 / 70] (score: 2)
arXiv:2610.37910 [pdf, ps, other]

Title: Generative modeling for fusion: a large-scale benchmark of stellarator fast-ion simulations

Authors: Misha Padidar, Teresa Huang, Mark Goldstein, Michael Czekanski, Jeffrey Soules,

Comments:

Subjects: cs.LG physics.plasm-ph

Created: 2026-10-27; Updated: 2026-10-30; Datestamp: 2026-10-30

Stellarators offer a promising MAGNETic confinement approach for achieving controlled nuclear fusion. However, stellarator design remains challenging, as evaluating configuration performance requires computationally expensive, high-fidelity simulations. In particular, key performance metrics derived from guiding center simulations are costly to include directly in the design optimization loop, and are almost exclusively used as diagnostics. Machine learning has the potential to advance fusion research by enabling rapid generation and evaluation of new stellarator configurations. Effectively applying ML for fusion demands large-scale datasets that capture both design diversity and high-fidelity simulation outputs. In this work, we introduce the Benchmark of Stellarator Simulations (BoSS), a dataset of stellarator designs paired with guiding center simulation results and trajectories. The BoSS is the first large-scale dataset of guiding center simulations, containing simulation data for 180,000 distinct MAGNETohydrodynamic equilibria spanning a wide range of MAGNETic geometries and confinement properties. To exemplify the utility of ML to accelerate stellarator design, we formulate and address two sets of modeling tasks: generative modeling for designing stellarators with good particle confinement, and surrogate modeling for predicting stellarator heat deposition patterns and particle trajectories. The tasks reveal the potential impact ML can have in the stellarator field and important opportunities to improve the applicability of ML models in the sciences. Our baselines generate diverse, performant stellarators and provide useful surrogate predictions, and point to long-horizon trajectory forecasting and out-of-distribution generation as key directions for future work. The BoSS can be accessed through https://boss.flatironinstitute.org/.

[abstract 59 / 70] (score: 2)
arXiv:2610.37997 [pdf, ps, other]

Title: Search for Eccentric Neutron Star-Black Hole Binaries in Advanced LIGO's Fourth Observing Run using Effective-One-Body Waveforms

Authors: Aleyna Akyüz, Keisi Kacanja, Rahul Dhurkunde, Alexander H. Nitz,

Comments: 20 pages, 16 figures, 1 table

Subjects: astro-ph.HE gr-qc

Created: 2026-10-27; Updated: 2026-10-30; Datestamp: 2026-10-30

The observation of orbital eccentricity in compact binary coalescences would provide a direct signature of dynamical formation environments. Previous matched-filter searches for eccentric neutron star-BLACK HOLE (NSBH) binaries have been severely limited by computational constraints, necessitating the use of simplified waveform models that capture secular dephasing but omit apsidal precession and inter-orbit harmonics. Including these physical features increases the sensitive search volume for systems with $0.2 \le e_{20} \le 0.28$ by $\sim 25\%$ to $30\%$. We present a rapid matched-filter search methodology that makes the direct use of time-domain effective-one-body waveforms computationally feasible. By multibanding and high-frequency ratio-filtering, our pipeline achieves a $\sim 20\times$ reduction in computational cost. This allows a bank of 88.6 million effective-one-body templates, fifteen times larger than prior eccentric analyses, to search O4a and O4b Advanced LIGO data. We recover the known low-mass mergers GW230518_125908 and GW230529_181500 with parameters consistent with zero eccentricity. Finding no new gravitational-wave events with orbital eccentricity ($e_{20} \ge 0.05$), we place $90\%$ credible upper limits on the local merger rate density of eccentric NSBH systems across the search space of $\mathcal{R}_{90\%} \le 7.5\text{-}57\ \mathrm{Gpc}^{-3}\ \mathrm{yr}^{-1}$, up to a factor of $\sim 4$ improvement over previous observational bounds. At the parameters of GW200105_162426, this non-detection establishes an upper limit of $\mathcal{R}_{90\%} \le 12.1\ \mathrm{Gpc}^{-3}\ \mathrm{yr}^{-1}$. Alternatively, if GW200105_162426 is treated as an eccentric detection, the lack of subsequent detections in O4 updates the inferred local merger rate density of this population to $\mathcal{R} = 6.6^{+6.3}_{-3.8}\ \mathrm{Gpc}^{-3}\ \mathrm{yr}^{-1}$.

[abstract 60 / 70] (score: 2)
arXiv:2610.38068 [pdf, ps, other]

Title: Physical Effects in the Vicinity of Black Holes

Authors: Alex Koek,

Comments: PhD thesis, University of Alberta, Supervisor: Professor Valeri P. Frolov. 204 pages, 16 figures

Subjects: gr-qc

Created: 2026-10-27; Updated: 2026-10-30; Datestamp: 2026-10-30

General relativity, a theory that is already over a century old, is still the best theory that we have to describe the universe at energy scales where only the gravitational force is important. It has stood tall to any observational tests thrown at it since its inception, and it has remarkable predictive power when it is utilized to study and model astrophysical problems. It also continues to surprise us with its ability to generate new problems and insights that render themselves useful in the study of modern physics. This is especially highlighted by the transition of modern observational astronomy away from an electroMAGNETic radiation epoch, and into a new gravitational wave epoch. This thesis devotes its study to phenomena that can be analyzed within the framework of classical general relativity, but whose results may contain interesting implications for cosmological and BLACK HOLE observations. (Full abstract can be found in document).

[abstract 61 / 70] (score: 2)
arXiv:2610.38083 [pdf, ps, other]

Title: The scale of homogeneity in DESI Data Release 1

Authors: Cullan Howlett, L. Giani, Elizabeth G. O'Brien, A. Whitford, Tamara M. Davis, J. Aguilar, S. Ahlen, U. Andrade, E. Armengaud, S. BenZvi, F. Beutler, D. Bianchi, D. Brooks, R. Canning, A. Carnero Rosell, F. J. Castander, E. Chaussidon, T. Claybaugh, A. Cuceu, A. de la Macorra, Arjun Dey, Biprateep Dey, P. Doel, D. Forero-Sánchez, J. E. Forero-Romero, E. Gaztañaga, Satya Gontcho A Gontcho, G. Gutierrez, C. Hahn, K. Honscheid, D. Huterer, M. Ishak, S. Juneau, T. Karim, D. Kirkby, A. Kremin, O. Lahav, A. Lambert, C. Lamman, M. Landriau, L. Le Guillou, M. Manera, A. Meisner, R. Miquel, J. Moustakas, S. Nadathur, J. A. Newman, H. E. Noriega, E. Paillas, N. Palanque-Delabrouille, W. J. Percival, C. Poppett, F. Prada, I. Pérez-Ràfols, C. Ravoux, G. Rossi, R. Ruggeri, L. Samushia, E. Sanchez, C. Saulder, E. F. Schlafly, D. Schlegel, M. Schubnell, J. Silber, M. Siudek, G. Tarlé, B. A. Weaver, H. Zou,

Comments: 19 pages, 11 figures, 5 tables. Submitted to the Publications of the Astronomical Society of Australia

Subjects: astro-ph.CO

Created: 2026-10-27; Updated: 2026-10-30; Datestamp: 2026-10-30

We present measurements of the scale of cosmic homogeneity using the first data release (DR1) of the Dark Energy Spectroscopic Instrument (DESI), the largest publicly available spectroscopic extragalactic survey to date. Using a counts-in-spheres estimator applied to nearly 5 million galaxies and QUASARs across six independent redshift bins spanning $0.1 < z < 2.1$, we measure the correlation dimension $D_2(r)$ and define the homogeneity scale $R_H$ as the point at which the galaxy distribution reaches within 1\% of the homogeneous asymptotic value. We find that all tracers clearly transition to homogeneity, with the galaxy homogeneity scale ranging from $93.8^{+0.9}_{-0.7}$ to $142.6^{+1.4}_{-1.4}$ $h^{-1}$Mpc depending on the tracer redshift, galaxy bias, and modelling used to extract the scale. Using a cosmology-dependent model, we reconstruct the underlying matter homogeneity scale, finding it decreases monotonically with redshift in excellent agreement with $Λ$CDM predictions. We identify a systematic offset of up to $\sim 10\%$ between measurements in the North and South Galactic Caps, largely due to fiber assignment effects reproduced in our simulations. Accounting for this, and with a complementary demonstration using toy models that our methodology correctly identifies inhomogeneous universes in all but rather finely-tuned observer configurations, this hence provides strong evidence in favour of the cosmological principle across our full redshift range. Our matter homogeneity scale measurements are consistent with, and substantially more precise than, previous constraints from WiggleZ and SDSS, demonstrating the power of DESI data for precision tests of the cosmological principle.

[abstract 62 / 70] (score: 2)
arXiv:2610.38107 [pdf, ps, other]

Title: Tayler Instability and Its Saturation in Rotating Stars

Authors: Valentin Skoutnev, Andrei Beloborodov,

Comments: Submitted to ApJ

Subjects: astro-ph.SR astro-ph.HE physics.flu-dyn

Created: 2026-10-28; Updated: 2026-10-30; Datestamp: 2026-10-30

In stably stratified regions of rotating stars, MAGNETic instabilities play a key role by enabling dynamo and angular momentum transport. In particular, the Tayler instability of wound-up toroidal fields has long been considered to drive the Tayler-Spruit dynamo. However, the nonlinear saturation of the instability is poorly understood, despite its central role in the dynamo loop. In this paper, we use global simulations to verify the recently completed linear theory of the Tayler instability and determine its saturation. We confirm the picture of overstability of MAGNETostrophic and inertial waves, which grow on similar MAGNETostrophic timescales but oscillate with different frequencies. We find that MAGNETostrophic waves saturate with large amplitudes $δB/B\sim 1$ and dissipate the toroidal field on MAGNETostrophic timescales, while inertial waves saturate with $δB/B\ll 1$ and erode the toroidal field over much longer timescales. Moreover, MAGNETostrophic waves efficiently regenerate axisymmetric poloidal fields through nonlinear couplings while inertial waves do not. Our results indicate that the Tayler-Spruit dynamo can operate only through the MAGNETostrophic wave branch and that its steady-state may follow the scenario proposed by \cite{spruit2002dynamo}, ruling out the small-amplitude saturation scenario proposed by \cite{fuller2019slowing}. Implications for angular momentum transport and MAGNETic field amplification in evolving stars and nascent neutron stars are discussed.

[abstract 63 / 70] (score: 2)
arXiv:2610.38232 [pdf, ps, other]

Title: A Spectral-model-independent Diagnostic of Phase-resolved Spectral Convergence in SWIFT J0243.6+6124

Authors: Bo-Yan Chen, Peng-Ju Wang, Shu Zhang, Ling-Da Kong, Long Ji, Shuang-Nan Zhang, Hua Feng, Yu-Peng Chen, Ming-Yu Ge, Jing-Qiang Peng, Qing-Cang Shui, Wen-Zhong Li,

Comments: 9 pages, 7 figures (4 main-text figures and 3 appendix figures)

Subjects: astro-ph.HE

Created: 2026-10-28; Updated: 2026-10-30; Datestamp: 2026-10-30

We introduce a spectral-model-independent spectral-shape metric, $δ_{\rm rms}$, to probe phase-resolved spectral evolution in the Galactic ultraluminous X-ray pulsar SWIFT J0243.6+6124. The $δ_{\rm rms}$--luminosity relation reveals a reproducible convergence--redivergence behavior: spectra from two geometrically opposite pulse phases converge to near identity around $L_{\rm t}^{\ast}\sim8.8\times10^{37}\ \mathrm{erg\ s^{-1}}$, with a mean shape difference of only $\sim2\%$, and rediverge at higher luminosities, most prominently at higher energies. This strong phase-resolved spectral convergence coincides with a pulse-profile reversal and traces the same transition luminosities previously identified from broadband continuum evolution, including $L_{\rm t}\sim4.5\times10^{37}\ \mathrm{erg\ s^{-1}}$. These results suggest a possible luminosity-driven reweighting between a broadly distributed surface-reprocessed/reflected component and an increasingly important direct accretion-column contribution, while establishing $δ_{\rm rms}$ as a robust, spectral-model-independent diagnostic of radiation-geometry restructuring in bright accreting X-ray pulsars.

[abstract 64 / 70] (score: 2)
arXiv:2610.38742 [pdf, ps, other]

Title: Isospectrality breaking in the axial quasinormal modes of Reissner-Nordström BLACK HOLEs in dynamical Chern-Simons gravity

Authors: Abhishek Rout,

Comments: 25 pages, 6 figures; code: doi:10.5281/zenodo.23283164

Subjects: gr-qc

Created: 2026-10-28; Updated: 2026-10-30; Datestamp: 2026-10-30

We study odd-parity perturbations of Reissner-Nordström BLACK HOLEs in dynamical Chern-Simons gravity. The dCS action is parity invariant because $\vartheta\,{}^{*}RR$ is the product of two pseudoscalars; nevertheless, the pseudoscalar perturbation has odd parity and enters only the axial sector at linear order and so lifts the axial--polar isospectrality of general relativity. We derive the finite-charge couplings between the pseudoscalar and the axial gravitational and electroMAGNETic perturbations directly from the linearized field equations. Both directions are governed by the radial kernel $(Mr-Q^2)Δ/r^8$, and at nonzero charge the pseudoscalar couples to $Ψ+χΨ_e$, with $χ=2Q/[r\sqrt{(l-1)(l+2)}]$. After diagonalizing the Einstein--Maxwell sector, we compute branch-resolved quasinormal-mode shifts with exterior complex scaling for the photon-sphere modes and Frobenius shooting for the near-extremal zero-damping modes. For the Schwarzschild $l=2$ fundamental mode we obtain $β\,δω=-0.7733-0.3946\,i$ (units $M=α=1$). Off resonance, the gravitational-led shift scales as $ζ\,l^3$ at $Q=0$ but as $ζ\,l^2/Q$ at fixed nonzero charge and large $l$. The electroMAGNETic-led branch becomes exactly degenerate with the pseudoscalar mode at $Q_c=2M\sqrt{l(l+1)+1}/[l(l+1)+2]$, where the pseudoscalar potential coincides with the polar partner of the electroMAGNETic-led potential; there the breaking is $\mathcal{O}(\sqrtζ)$, $M|Δω|\simeq2.4\sqrtζ$ for $l=2$, and the shift reverses sign across $Q_c$. Near extremality the photon-sphere shifts remain finite, whereas the non-degenerate fundamental gravitational-led zero-damping mode is suppressed, $δω/ω\simeq6.0\times10^{3}\,ζ\,(1-Q^2/M^2)$ for $l=2$.

[abstract 65 / 70] (score: 2)
arXiv:2610.38839 [pdf, ps, other]

Title: Diffusion model for fast alpha-particle transport in Magneto-Inertial Fusion plasmas

Authors: Alexander Velikovich, Fernando García-Rubio, Scott Davidson, Lee Ellison, Jason Hamilton, Paul Schmit,

Comments: 112 pages, 23 figures, 80 references

Subjects: physics.plasm-ph

Created: 2026-10-28; Updated: 2026-10-30; Datestamp: 2026-10-30

A diffusion model is developed to describe fast alpha-particle transport and confinement in dense MAGNETized DT fusion plasmas, tailored to Magneto-Inertial Fusion conditions. The model, derived from the Fokker-Planck kinetic equation using the Chapman-Enskog approximation, includes dynamic Coulomb friction from electrons and ions. This approach improves upon earlier heuristic model [Liberman and Velikovich, J. Plasma Phys. 31, 369 (1984)], which, while valid in the ignition range near 5 keV, lacks accuracy at the higher temperatures ~20 keV required for high-gain Magnetized Liner Inertial Fusion (MagLIF). This paper provides explicit analytic formulas for all transport coefficients and characterizes the relationship between the alpha-particle pressure gradient and the associated Ampère force in MAGNETized plasmas, which are both relevant for MagLIF at high temperatures.

[abstract 66 / 70] (score: 2)
arXiv:2610.38931 [pdf, ps, other]

Title: High-Repetition-Rate Laser-Driven Fast Neutron Generation from Planar Liquid Heavy Water Jets

Authors: F. Treffert, G. D. Glenn, C. B. Curry, D. P. DePonte, R. C. Hollinger, G. Jain, S. Popa, M. Ricks, J. J. Rocca, B. Sullivan, D. Ursescu, S. Wang, G. J. Williams, S. Zahedpour, S. H. Glenzer, M. Gauthier,

Comments: 13 pages, 6 figures. F. Treffert and G. D. Glenn contributed equally to this work

Subjects: physics.plasm-ph

Created: 2026-10-28; Updated: 2026-10-30; Datestamp: 2026-10-30

We demonstrate a high-repetition-rate, directional pitcher-catcher neutron source employing a continuously flowing, ambient-temperature liquid JET pitcher and a beryllium catcher target. Proton or deuteron beams are accelerated at 0.5 Hz from water (H$_{2}$O) or heavy water (D$_{2}$O) sheet JETs using the $2ω$ ALEPH LASER at Colorado State University. Deuteron-induced neutron generation shows an average flux enhancement in the target normal direction of 13x compared to proton-induced neutron generation, achieving peak fluxes of $7.9\times10^{5}$ neutrons/sr. The experimentally predicted ion-to-neutron conversion efficiency of 1.5$\times 10^{-5}$ for protons and 1.1$\times 10^{-3}$ for deuterons indicates a significant yield contribution from the deuteron breakup reaction. High shot-to-shot stability neutron spectra up to 8.7~MeV ($^9$Be(d,n)$^{10}$B) are observed for more than 200 consecutive shots.

[abstract 67 / 70] (score: 2)
arXiv:2610.39522 [pdf, ps, other]

Title: Causality-informed dynamic mode decomposition for unsteady flow analysis

Authors: Yihua Pan, Jiaqing Kou,

Comments:

Subjects: physics.flu-dyn

Created: 2026-10-29; Updated: 2026-10-30; Datestamp: 2026-10-30

Causal analysis characterizes directional dependencies in dynamical systems, while such information is not typically used to inform reduced-order modeling of unsteady flows. This study proposes a Granger Causality-informed Dynamic Mode Decomposition (GC-DMD) framework that incorporates such information into data-driven modeling and modal analysis of high-dimensional flow data. The framework uses conditional Granger causality estimates to regularize the identification of the DMD operator, preferentially suppressing weakly supported interactions while preserving dynamically relevant couplings. This regularization promotes sparse operators informed by directional predictive dependencies, leading to improved predictive accuracy and identification of dynamically relevant modes. GC-DMD is evaluated on a linear system with a known coupling structure, lid-driven cavity flows with varying dynamical complexity, and a broadband transonic turbulent JET. Compared with standard DMD, GC-DMD improves operator identification accuracy in the linear benchmark and improves the robustness of the identified spectrum while reducing long-horizon prediction errors in the cavity flows. For the turbulent JET, it yields a sparser operator with improved prediction accuracy. These results demonstrate the potential of incorporating causality information to guide the identification of sparse, predictive reduced-order models of complex flows. The \href{https://github.com/JiaqingKou/GC-DMD-Granger-Causality-informed-DMD}{source codes} \footnote{https://github.com/JiaqingKou/GC-DMD-Granger-Causality-informed-DMD} from this research are publicly available in the GitHub repository.

[abstract 68 / 70] (score: 2)
arXiv:2610.39808 [pdf, ps, other]

Title: Magnetic shocks generated by two counterstreaming plasma JETs induced by an intense femtosecond LASER pulse

Authors: R. S. Zemskov, A. V. Kotov, S. E. Perevalov, A. A. Murzanev, A. I. Korytin, P. A. Chuvakin, A. V. Romashkin, V. N. Ginzburg, A. A. Kochetkov, S. E. Stukachev, I. V. Yakovlev, I. A. Shaikin, A. A. Kuzmin, K. F. Burdonov, A. A. Soloviev, A. A. Shaykin, A. N. Stepanov, M. V. Barkov, E. A. Khazanov, M. V. Starodubtsev,

Comments:

Subjects: physics.plasm-ph

Created: 2026-10-29; Updated: 2026-10-30; Datestamp: 2026-10-30

This work extends the investigation of MAGNETic control of counterstreaming LASER-produced plasma JETs reported in Zemskov et al. (2026), focusing on the experiments performed in the presence of a uniform 14 T MAGNETic field oriented transverse to the JET propagation. When generating plasma flows using 60-80 fs, 10-15 J pulses at the PEARL facility, we observe the formation of narrow, stationary layers with strong MAGNETic-field amplification and sharp plasma-density gradients in the interaction region. We interpret these features as the result of compressing the externally applied transverse field by the converging plasma ram pressure. The external MAGNETic field is advected and compressed until its MAGNETic pressure balances the decreasing ram pressure of the JETs. Time-resolved interferometry, shadowgraphy, and Faraday polarimetry, combined with hybrid PIC--fluid simulations, reproduce the formation of a high-field barrier that decelerates and laterally redirects plasma flows while producing multiple density jumps. We discuss the astrophysical implications: the compression of an initially weak ambient field by converging flows provides an efficient, non-turbulent channel for MAGNETic-field amplification that can render interstellar MAGNETic fields dynamically important - a condition essential for diffusive shock acceleration in SUPERNOVA remnants. Our experiments therefore establish a laboratory platform bridging externally MAGNETized and self-MAGNETized regimes and offer a complementary route to MAGNETic-field amplification in high-energy astrophysical shocks.

[abstract 69 / 70] (score: 2)
arXiv:2610.39864 [pdf, ps, other]

Title: ElectroMAGNETic emission at the Langmuir frequency from LASER interaction with an unMAGNETized plasma

Authors: J. -R. Marquès, F. Pérez, P. Loiseau, L. Lancia, C. Briand, S. Depierreux, M. Grech, C. Riconda,

Comments: Submitted to Physical Review Letters

Subjects: physics.plasm-ph

Created: 2026-10-29; Updated: 2026-10-30; Datestamp: 2026-10-30

We present the first experimental observation of electroMAGNETic emission at the Langmuir frequency, $ω_p$, resulting from LASER-plasma interaction in an underdense and unMAGNETised plasma. The emission is spatially resolved and analyzed in POLARIZATION. It originates from an electrostatic wave excited by the Raman instability. Despite its frequency being very close to the plasma's cutoff frequency, $ω_{pe}$, this radiation can escape the plasma by following the decreasing slope of the plasma density profile. Radiation at $2ω_p$, is also observed. This experimental platform offers a powerful tool to explore the processes of wave coupling at the origin of some radio solar bursts.

[abstract 70 / 70] (score: 2)
arXiv:2610.39865 [pdf, ps, other]

Title: VERITAS Limits on Dark Matter Annihilation in the Galactic Center Halo

Authors: A. Archer, P. Bangale, J. T. Bartkoske, W. Benbow, N. R. Bond, J. H. Buckley, Y. Chen, J. L. Christiansen, A. J. Chromey, A. Duerr, M. Errando, M. Escobar Godoy, J. Escudero Pedrosa, S. Feldman, Q. Feng, S. Filbert, L. Fortson, A. Furniss, W. Hanlon, O. Hervet, C. E. Hinrichs, J. Holder, D. Huang, T. B. Humensky, M. Iskakova, W. Jin, E. Joshi, M. Kertzman, M. Kherlakian, D. Kieda, T. K. Kleiner, N. Korzoun, S. Kundu, M. J. Lang, M. Lundy, G. Maier, M. R. Martin, P. Moriarty, R. Mukherjee, W. Ning, M. Ohishi, R. A. Ong, A. Pandey, M. Pohl, J. Quinn, P. L. Rabinowitz, K. Ragan, P. T. Reynolds, E. Roache, J. L. Ryan, I. Sadeh, L. Saha, H. Salzmann, M. Santander, G. H. Sembroski, D. Tak, J. V. Tucci, V. V. Vassiliev, D. A. Williams, S. L. Wong, T. Yoshikoshi,

Comments:

Subjects: astro-ph.HE

Created: 2026-10-29; Updated: 2026-10-30; Datestamp: 2026-10-30

Well-motivated models of particle DARK MATTER predict its self-annihilation into Standard Model end states, which may be detected by particle detectors or telescopes. We conduct an indirect DARK MATTER search using gamma rays detected by the VERITAS telescope from within $2^\circ$ of the Galactic Center. A template-based approach is used for background estimation, increasing our sensitivity to sources of gamma-ray emission with spatial extents comparable to the $3.5^\circ$ VERITAS field of view. The analysis benefits from data taken exclusively at large zenith angles, which results in an increased effective area at energies above ~1 TeV, compared to small zenith angle observations. No significant gamma-ray signal is observed in the search region, resulting in upper limits on the end-state-dependent DARK MATTER annihilation cross sections. Cross sections as low as $\langle σ_\text{ann} v\rangle = 1.77\times 10^{-25} \text{ cm}^3 \text{ s}^{-1}$ are excluded at 95% confidence assuming complete annihilation into $τ^+ τ^-$, an Einasto profile, and a DARK MATTER mass of 1 TeV.