Current date: 2026-10-19

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Datestamp limit: 2026-10-19 (0 days ago)

Created/updated limit: 2026-10-12 (7 days ago)

Suggested sets: physics, physics:astro-ph, physics:gr-qc, physics:physics

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OAI-PMH request: http://export.arxiv.org/oai2?verb=ListRecords&from=2026-10-19&until=2026-10-19&set=physics&metadataPrefix=arXiv

Scoring abstracts

Number of records retrieved: 194

Keyword score statistics

score 7 -- 2 abstracts

score 6 -- 2 abstracts

score 4 -- 2 abstracts

score 3 -- 3 abstracts

score 2 -- 3 abstracts

in total -- 12 abstracts

Articles that appeared on 2026-10-19

[abstract 1 / 12] Wow! (score: 7)
arXiv:2610.18285 [pdf, ps, other]

Title: EMU detection of mysterious multiple component radio-continuum emission from nearby spiral Seyfert I type galaxy 'Sand-timer' (NGC 7213)

Authors: M. D. Filipović, Z. J. Smeaton, B. S. Koribalski, R. Kothes, A. Ahmad, R. Z. E. Alsaberi, C. Bordiu, A. C. Bradley, E. J. Crawford, A. M. Hopkins, E. Järvelä, S. Lazarević, D. Leahy, J. L. Payne, S. F. ur Rahman, G. P. Rowell, H. Sano, M. Selby, S. S. Shabala, E. J. Stanton, S. Taziaux, K. Tsuge, D. Urosević, N. F. H. Tothill, J. Th. van Loon, V. Velović, G. L. White,

Comments: Published in the Open Journal of Astrophysics

Subjects: astro-ph.GA

Created: 2026-10-15; Updated: 2026-10-19; Datestamp: 2026-10-19

We present an Australian Square Kilometre Array Pathfinder (ASKAP) Evolutionary Map of the Universe (EMU) radio-continuum detection of the nearby spiral Seyfert I type galaxy NGC 7213 which we nickname `Sand-timer' due to its morphological appearance. We find intriguing, peculiar emission extending from the central supermassive BLACK HOLE (SMBH), which we refer to as galaxy hyperbubbles and/or ACTIVE GALACTIC NUCLEus (AGN) JETs. Finally, we find two previously undetected kiloparsec-scale features in the polarised intensity image, which appear most likely also related to the central SMBH, as restarted bipolar radio JETs, though somewhat obscured in the radio-continuum total intensity image. They resemble the bow shocks often seen in Fanaroff-Riley Class II (FR-II) RADIO GALAXies, and so we propose they most likely represent an early episode of the `Sand-timer's' AGN JET activity. An alternative scenario is that the core of NGC 7213 may be a supermassive binary BLACK HOLE (SMBBH) undergoing a tidal disruption event (TDE), potentially causing the peculiar radio-continuum emission.

[abstract 2 / 12] Wow! (score: 7)
arXiv:2610.22653 [pdf, ps, other]

Title: Sparking Dynamic, Relativistic Magnetic Reconnection in a Twisted Flux Tube

Authors: Michael P. Grehan, Christopher Thompson, Bart Ripperda, James R. Beattie,

Comments: 31 pages, Figure 26, submitted to ApJ

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

Created: 2026-10-15; Updated: 2026-10-19; Datestamp: 2026-10-19

Magnetic RECONNECTion around neutron stars (NSs) forms small-scale currents while transferring energy to electron-positron pairs. These dissipating currents cover a wide range of scales, potentially leaving an imprint on time-variable X-ray bursts and pulsed radio emission. We present a reduced, planar model of internal RECONNECTion in a MAGNETic flux tube with RELATIVISTIC MAGNETization, finite resistivity, and strong guide field. Comparing with realistic NS parameters, this model represents the dynamics of a slender MAGNETic flux tube that is much thinner than the stellar radius. The seed current profile is smooth and does not spontaneously RECONNECT; instead, a discrete and localized current perturbation is introduced, representing e.g. localized energy release from a NS crust or MAGNETosphere. Three high-resolution RELATIVISTIC MAGNETohydrodynamics simulations are described: one has uniform resistivity and Lundquist number such that RECONNECTion proceeds in the plasmoid-mediated regime; the other two account for the feedback of charge starvation on the resistivity in current layers, where density is depleted; we provide a more general explanation for this depletion. All simulations produce a few dominant MAGNETic X-points and a secondary Kelvin-Helmholtz instability that excites high-wavenumber currents. We quantify the RECONNECTion rate, the intermittency of dissipation, and the time profile of current spikes. We further present three-dimensional simulations confirming a limited growth of the ideal kink mode in the strong guide field regime. Applications are discussed, including to radio pulse microstructure and current damping below the MAGNETar surface during an X-ray flare, leading to mass loss and X-ray afterglow.

[abstract 3 / 12] Yes (score: 6)
arXiv:2610.13288 [pdf, ps, other]

Title: Resistive alignment of a black-hole MAGNETosphere

Authors: Ruben Lier, Oliver Porth,

Comments:

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

Created: 2026-10-15; Updated: 2026-10-19; Datestamp: 2026-10-19

Recent numerical simulations have shown that black-hole MAGNETospheres evolve rapidly toward alignment between the MAGNETic axis and spin axis but the physical origin of this process has remained unclear. We develop an analytic theory of this alignment within resistive RELATIVISTIC MAGNETohydrodynamics. Taking the slow-spin Blandford-Znajek monopole solution as the exterior MAGNETic field, we reduce the induction equation to a relaxation equation for the current-sheet inclination angle. Our analysis shows that alignment results from second-order spin effects in the Blandford-Znajek solution combined with explicit resistive dissipation. We test this prediction using resistive-GRMHD simulations at several spins and resistivities and compare the measured late-time secular decay with the analytic prediction. This alignment timescale hence carries a unique signature which combines plasma dissipation with spacetime rotation.

[abstract 4 / 12] Yes (score: 6)
arXiv:2610.22662 [pdf, ps, other]

Title: The transformative power of ALMA2040 for mm-VLBI

Authors: The Event Horizon Telescope Collaboration,

Comments: 16 pages, 3 figures. Part of the ALMA2040 White Paper Series

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

Created: 2026-10-15; Updated: 2026-10-19; Datestamp: 2026-10-19

The Event Horizon Telescope (EHT) has resolved horizon-scale emission in M87* and Sgr A*. Extending these observations to fainter BLACK HOLEs, multiple frequencies, and evolving structures requires greater sensitivity and new observing capabilities. We investigate how ALMA2040 could expand the scientific reach of global millimeter very long baseline interferometry (mm-VLBI), compared with ALMA's Wideband Sensitivity Upgrade (WSU). Phasing a larger ALMA array and enabling simultaneous observations across multiple ALMA bands would improve sensitivity and frequency phase transfer, providing spectral and polarimetric diagnostics of gravity, accretion flows, MAGNETic fields, and RELATIVISTIC JETs. In the configurations studied, ALMA2040 achieves sub-mJy baseline sensitivity at 230 GHz and improves prospects for faint-source imaging at 345 GHz, opening a path from individual horizon-scale targets toward population studies. Simulated observations of M87* show improved multi-frequency recovery of emission from the compact ring-like region toward the JET base, enabling studies of the accretion-JET connection. For Sgr A*, simulations of interstellar scattering mitigation yield a 27% reduction in the error of the recovered intrinsic source structure relative to the WSU configuration. Beyond BLACK HOLEs, these capabilities benefit geometric-distance measurements, stellar masers, compact transients, and other applications of high-resolution astrophysics. Together with rapid-response capabilities across the VLBI network, ALMA2040 could support a transition from isolated snapshots toward multi-frequency, time-resolved studies of compact sources.

[abstract 5 / 12] Yes (score: 4)
arXiv:2607.18315 [pdf, ps, other]

Title: Gas Motions in Hydra-A: XRISM Constraints on ICM Kinematics Across Jet-Inflated Cavities

Authors: Anwesh Majumder, B. R. McNamara, P. E. J. Nulsen, H. Russell, T. Rose, T. Heckman, A. Simionescu, A. Fabian, M. W. Wise, N. Werner, M. McDonald,

Comments: 17 pages, 6 figures; Accepted in ApJ

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

Created: 2026-10-15; Updated: 2026-10-19; Datestamp: 2026-10-19

We report on two deep XRISM observations of the central and northern regions of Hydra-A's X-ray atmosphere, covering the bubbles inflated by JETs from the central galaxy's ACTIVE GALACTIC NUCLEus. We use spatial-spectral mixing, combining Chandra's high spatial resolution with XRISM's high spectral resolution, to investigate atmospheric kinematics. The velocity dispersion in the northern region, $σ_v = 140^{+30}_{-20}$ km s$^{-1}$, is comparable to that in the central region ($σ_v = 162 \pm 10$ km s$^{-1}$). We show that motion of the large-scale cocoon shock front could be responsible for the large dispersion toward the north. The dispersion in the northeast quarter of the central pointing, $σ_v = 260 \pm 50$ km s$^{-1}$, is among the highest measured. This region contains an X-ray-bright feature previously identified as metal-rich, possibly gas uplifted in the wake of previous-generation cavities. Dispersions in all other quarter regions are low ($σ_v \leq 180$ km s$^{-1}$) and consistent with previous XRISM results from other objects. The kinetic energy at the center is comparable to the enthalpies of the cavities, while in the north it is roughly an order of magnitude smaller. The JET thus drives gas motion efficiently at smaller scales ($r < 95$ kpc) and inefficiently at larger scales ($95-317$ kpc toward the north along the JET). A bulk flow toward our line of sight of $-100 \pm 30$ km s$^{-1}$ in the southwest quarter of the central pointing, measured with respect to the central galaxy, is also observed, possibly due to sloshing. No significant bulk motion was detected in any other region.

[abstract 6 / 12] Yes (score: 4)
arXiv:2608.06269 [pdf, ps, other]

Title: An "inside-out" approach to modeling supermassive BLACK HOLE binary inspiral

Authors: Laura Blecha,

Comments: 31 pages, 13 figures, accepted to ApJ

Subjects: astro-ph.HE

Created: 2026-10-15; Updated: 2026-10-19; Datestamp: 2026-10-19

The inspiral and merger of two supermassive BLACK HOLEs (SMBHs) releases immense energy in low-frequency gravitational waves (GWs). Recent pulsar timing array (PTA) observations of the stochastic nHz GW background (GWB) are consistent with a SMBH binary origin. GW data from PTAs and from the upcoming Laser Interferometer Space Antenna (LISA) can probe late-stage binary evolution where electroMAGNETic constraints are scarce. However, the complexity of the relevant astrophysics necessitates a well optimized approach. I argue that a key physical quantity to constrain with PTAs is the orbital semi-major axis at which binary inspiral transitions from the astrophysical to the GW-dominated regime ($a_{\rm GW}$). This quantity should be treated as a free parameter in analysis of the GWB. Using this premise, I present a simple analytic framework for modeling SMBH binary inspiral in an "inside-out" fashion. At orbital separations slightly larger than $a_{\rm GW}$, a power-law scaling for the astrophysical inspiral timescale is assumed, while the outermost phase (prior to the PTA regime) is simply modeled via a delay time. I show that the GWB spectral shape and amplitude are most sensitive to $a_{\rm GW}$ (normalized to $10^9 M_{\odot}$, equal-mass binaries and expressed in gravitational units), with weaker dependence on the inner power-law index and the outer delay time. The GWB is largely insensitive to the mass and mass-ratio scaling of $a_{\rm GW}$ and to the boundary between the inner and outer astrophysical inspiral regimes. I compare with models for gas- and stellar-driven binary inspiral and discuss implications for LISA and for GW source parameter inference.

[abstract 7 / 12] (score: 3)
arXiv:2609.25958 [pdf, ps, other]

Title: IXPE observation of the new MAGNETar source EP J223759.5+531421

Authors: Roberto Taverna, Lorenzo Marra, Roberto Turolla, Ruth M. E. Kelly, Silvia Zane, Alice Borghese, Francesco Coti Zelati, Paolo Esposito, Gian Luca Israel, Nanda Rea, Haonan Yang, Yilong Wang,

Comments: 14 pages, 9 figures, accepted for publication in ApJL

Subjects: astro-ph.HE

Created: 2026-10-15; Updated: 2026-10-19; Datestamp: 2026-10-19

We report on the detection of polarized X-ray emission from the new Galactic MAGNETar EP J223759.5+531421, discovered by the Einstein Probe Wide-field X-ray Telescope on 2026 June 28. The Imaging X-ray Polarimetry Explorer (IXPE) follow-up observation started on 2026 July 6 and detected the source at a (absorbed) flux of $\approx 4.5\times 10^{-11} \, \mathrm{ erg\,cm^2\,s}^{-1}$ ($2$--$7.5\, \mathrm{keV}$ range), confirming the presence of two thermally emitting regions on the star surface, with temperatures $\approx 0.5$ and $\approx 1\, \mathrm{keV}$. A significant (at $> 4σ$ confidence level) phase- and energy-integrated POLARIZATION degree of $\approx 7\%$ was detected with the POLARIZATION angle $\approx -2^\circ$ East of the celestial North. The two thermal components exhibit quite different POLARIZATION properties, with the hotter one being more polarized. The difference is larger in the phase-folded data, with the POLARIZATION degree reaching $\sim 63\%$ in the range $4$--$7.5\,\mathrm{keV}$, in correspondence with the secondary peak of the pulse profile, and never exceeding $\sim 30\%$ at lower energies. The POLARIZATION angle continuously oscillates from $-90^\circ$ to $+90^\circ$ over one rotational cycle and is well fit by the rotating vector model, with an inclination of the line of sight and of the MAGNETic dipole axis relative to the star spin axis of $\approx 28^\circ$ and $\approx 109^\circ$, respectively. The data point to an emission geometry in which the cold thermal component likely originates from two antipodal caps, possibly in a MAGNETically condensed state, while the hotter one comes from a smaller region covered by an atmosphere.

[abstract 8 / 12] (score: 3)
arXiv:2610.22449 [pdf, ps, other]

Title: Resolving the AGN Feeding and Feedback Cycle with ALMA2040

Authors: Ilaria Ruffa, Francesco Salvestrini, Almudena Alonso Herrero, Anelise Audibert, Elena Bertola, Viviana Casasola, Roberto Decarli, Daniel Espada, Umberto Maio, Dieu D. Nguyen, Mamta Pandey-Pommier, Miguel Pereira-Santaella, Francesca Pozzi, Jahang Prathap, Sabine Thater, Maria Vittoria Zanchettin,

Comments: Part of the ALMA2040 White Paper Series. 10 pages, 4 Figures

Subjects: astro-ph.IM astro-ph.GA

Created: 2026-10-15; Updated: 2026-10-19; Datestamp: 2026-10-19

Understanding how supermassive BLACK HOLEs (SMBHs) grow and regulate the growth of their host galaxies requires tracing the cold molecular interstellar medium (ISM) throughout the full AGN feeding-feedback cycle. Molecular gas constitutes both the primary fuel for STAR FORMATION and black-hole accretion and one of the ISM phases most directly affected by AGN-driven radiation, winds, and radio JETs. Over the past decade, ALMA has resolved circumnuclear molecular discs, rings, spirals, tori, and JET-driven outflows on scales of tens of parsecs in nearby AGN. These studies have demonstrated that combining spatially resolved gas kinematics with multi-line diagnostics is essential for disentangling the physical processes underlying the observed gas conditions. However, our current picture remains largely based on a limited number of exceptionally nearby systems. Most local AGN have instead been observed with ALMA in a single transition at moderate or low angular resolution, preventing a systematic characterisation of both the dynamics and physical state of the gas. Moreover, existing studies have largely overlooked kinetic-mode AGN hosted by massive early-type galaxies, despite their central importance for understanding maintenance-mode feedback. In this White Paper, we argue that ALMA2040 should transform these detailed case studies into a statistical framework. A $\sim10\times$ improvement in line sensitivity relative to the current ALMA, together with fast mosaicking, ultra-wide instantaneous bandwidth, and longer baselines (resolving up to $\sim9$ mas at 230 GHz), will enable homogeneous, multi-line mapping of the molecular ISM on giant molecular clouds scales across statistically significant samples of both radiative- and kinetic-mode AGN out to $z\lesssim0.1$.

[abstract 9 / 12] (score: 3)
arXiv:2610.22480 [pdf, ps, other]

Title: Modeling extreme mass-ratio inspirals in astrophysical and dark-matter environments

Authors: Dongjun Li, Hao-Jui Kuan, Colin Weller, Chaoyi Yang, Kelvin Ka-Ho Lam, Patrick Bourg, Adrian Ka-Wai Chung, Yanbei Chen, Nicolás Yunes, Huan Yang,

Comments: 28 pages, 8 figures

Subjects: gr-qc astro-ph.HE

Created: 2026-10-15; Updated: 2026-10-19; Datestamp: 2026-10-19

Extreme mass-ratio inspirals offer a powerful probe of massive BLACK HOLEs and their environments, but interpreting their signals requires accurate models of orbital dynamics and radiation. Here we bring together advances in black-hole perturbation theory to establish a unified RELATIVISTIC framework for adiabatic inspirals in perturbative astrophysical environments. Built on the modified Teukolsky formalism, the framework requires neither post-Newtonian nor slow-rotation approximations. As a first application, we calculate the leading cloud-induced corrections to gravitational-wave fluxes and conservative orbital dynamics for circular, equatorial inspirals around a rotating BLACK HOLE surrounded by a synchronized ultralight scalar cloud, combining these corrections with the previously calculated scalar response. In our fiducial system, a cloud containing $10^{-4}$ of the black-hole mass produces about $-57.3$ radians of orbital dephasing over two years. The phase contributions from gravitational-wave flux corrections and background-induced orbital shifts each exceed the scalar contribution in magnitude and partially cancel, highlighting the need for coupled matter-gravity modeling. Extensible to other environments and modified gravity theories, our framework provides the RELATIVISTIC inputs needed to assess detection losses and parameter biases, and to probe the nature of black-hole environments with future space-based gravitational-wave observations.

[abstract 10 / 12] (score: 2)
arXiv:2511.12334 [pdf, ps, other]

Title: Clustering effects on the Dark Siren determination of $H_0$: A simulation study

Authors: Marios Kalomenopoulos, Riccardo Barbieri, Sadegh Khochfar, Jonathan Gair, Robert J. McGibbon,

Comments: Updated version, accepted in MNRAS

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

Created: 2026-10-15; Updated: 2026-10-19; Datestamp: 2026-10-19

We investigate the cosmological power of gravitational wave (GWs) events without electroMAGNETic counterparts using high-resolution, cosmological simulations that include realistic clustering. We assume a near-future detector network (LVK + LIGO India in O5), with sky localisation and distance uncertainty capabilities for binary BLACK HOLEs, of the order of $60$ deg. squared and $10\%$ respectively, and with a range of about $1600$ Mpc/h. We find that clustering leads to increased convergence of the $H_0$ posteriors, with clear recovery of the input value as early as $N_{\rm gw}=40$ events (a very conservative estimate for O5, which expects thousands of BBHs/year). In contrast, even with $N_{\rm gw}=100$ events in uniform catalogues, the posterior remains largely unconstrained. Additionally, we quantify the role of catalogue completeness and show that levels as low as $f=25\%$ can be competitive with fully complete catalogues, confirming the impact of clustering. Completeness levels of $f=50\%$ perform statistically similar to complete catalogues with as few as $N_{\rm gw}=40$ events. We conclude that improving GWs detection capabilities yields better results than more complete galaxy catalogues.Finally, we find that 1) physical weights do not provide significant additional constraining power on top of clustering, 2) luminosity distance errors contribute more for small cone openings, 3) the $H_0$ prior range does not introduce any biases in the $H_0$ posterior, 4) closer events ($\lesssim 100$ Mpc/h) yield about two times better precision than more distant events ($\lesssim 1600$ Mpc/h), and 5) our method is robust to different modelling choices.

[abstract 11 / 12] (score: 2)
arXiv:2610.22729 [pdf, ps, other]

Title: Pair-exchange dynamics of MAGNETohydrodynamic turbulence

Authors: Jean-Mathieu Teissier, Wolf-Christian Müller,

Comments:

Subjects: physics.flu-dyn astro-ph.IM astro-ph.SR physics.plasm-ph

Created: 2026-10-15; Updated: 2026-10-19; Datestamp: 2026-10-19

Nonlinear interactions in incompressible MAGNETohydrodynamic (MHD) and Navier-Stokes turbulence involve three spatial fluctuations conservatively exchanging, e.g., energy. The mathematical structure of a triad interaction does not allow to unambigously determine the specific contribution of each of the participating fluctuations to the resulting exchanges. Presently, only additional assumptions allow for the deconstruction of triad interactions into a sum of pair exchanges. This work proves that in incompressible MHD the simultaneous nonlinear transfer of cross-helicity sufficiently constrains the triad dynamics such that a mathematically unique pair-exchange representation of nonlinear energy and cross-helicity transfer is possible.

[abstract 12 / 12] (score: 2)
arXiv:2610.22780 [pdf, ps, other]

Title: Azimuthal Instability in Oscillating Liquid Jets by the Weber Number Variations

Authors: Hyoungwoo Kim, Seungwon Shin, Hyosang Yoon, Sanghyuen Park, Dong-hyuk Shin,

Comments: The following article has been submitted to Physics of Fluids

Subjects: physics.flu-dyn physics.comp-ph

Created: 2026-10-16; Updated: 2026-10-19; Datestamp: 2026-10-19

This paper investigates the dependence of azimuthal mode growth rate of oscillating liquid laminar JETs on the Weber number. The oscillating liquid laminar JETs were simulated over a range of Weber numbers. The simulation setup was validated by comparing the instantaneous interface shapes and the visible azimuthal mode from experimental measurements. As the Weber number increases, the spreading angle rises due to the small surface tension, and higher azimuthal modes are observed. Fourier Transform analysis is used to find the exact azimuthal mode of the simulation results. The dominant azimuthal mode increases as the Weber number increases. A power-law dependence of the growth rate on the Weber number is identified, with the obtained exponents showing good agreement with linear instability analysis. Furthermore, the rescaled Fast Fourier Transform (FFT) results collapse onto a single growth curve for each azimuthal mode, validating the proposed power-law for predicting the growth rates of oscillating liquid JETs.