Current date: 2026-10-06
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Number of records retrieved: 1300
Keyword score statistics
score 14 -- 1 abstracts
score 8 -- 1 abstracts
score 7 -- 1 abstracts
score 6 -- 2 abstracts
score 5 -- 1 abstracts
score 4 -- 7 abstracts
score 3 -- 14 abstracts
score 2 -- 16 abstracts
in total -- 43 abstracts
Articles that appeared on 2026-10-06
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[abstract 1 / 43] Wow! (score: 14)
- Title: Jets with Streaks: the Global Dynamics and Structure of Striped Poynting flux dominated JetsAuthors: Ho-Sang Chan, Anna Chashkina, Omer Bromberg, Gregory R. Werner, Hayk Hakobyan,Comments: 19 pages, 15 figuresSubjects: astro-ph.HE gr-qc physics.plasm-phCreated: 2026-10-03; Updated: 2026-10-06; Datestamp: 2026-10-06
Striped JETs, characterized by MAGNETically dominated regions with alternating polarity, can enable fast MAGNETic energy dissipation in global current sheets formed in between the stripes, and are thus considered as a viable source for the high-energy emission observed in BLAZARs and GAMMA-RAY BURST prompt emission. We perform the first global axisymmetric GRMHD simulations that follow the evolution of striped JETs from their launching, by accretion of poloidal MAGNETic loops with alternating polarity onto a spinning black-hole, to their energy dissipation at large distances. The accretion of each loop launches a Poynting-flux-dominated mini-JET carrying a helical MAGNETic field whose polarity is inherited from the loop, and the collection of which forms the JET core. The RELATIVISTIC core is surrounded by a non-RELATIVISTIC sheath composed of returning fieldlines from previously launched mini-JETs in a nested configuration. Efficient mini-JET launching requires poloidal loops in the accretion disk to form close to the BLACK HOLE ($r \lesssim 50\,r_g$); otherwise, they lose coherency due to turbulence. Once launched, the mini-JETs accelerate electroMAGNETically, similar to steady-state JETs, with the Lorentz factor increasing linearly with the JET cross-sectional radius as long as lateral causal contact with the JET axis is maintained. Current sheets form when two trailing mini-JETs carrying oppositely directed MAGNETic fields come into contact. Early sheet formation is facilitated by the longitudinal expansion of the mini-JETs, driven by internal pressure before the flow becomes super-fast-MAGNETosonic. We measure an energy dissipation rate of a few tens of percent of the JET Poynting power in the observer frame, within our simulation box of $10^4\,r_g$. Our results can account for the bright superluminal features observed in BL Lac type BLAZARs.
[abstract 2 / 43] Wow! (score: 8) - Title: Blasts from the Past: UHECR Excesses from a Population of GRB 21009A-like TransientsAuthors: Nestor Mirabal,Comments: 5 pages, 1 figureSubjects: astro-ph.HECreated: 2026-10-02; Updated: 2026-10-06; Datestamp: 2026-10-06
The most prominent feature in the ultra-high-energy COSMIC RAY (UHECR) sky is a significant excess of events from the vicinity of Centaurus A (Cen A). In this paper we investigate whether the excess may be caused by a past GRB 221009A-like event rather than Cen A itself. If an extraordinary GAMMA-RAY BURST (GRB) went off in one of the dwarf galaxies within the Cen A/M83 group, intergalactic MAGNETic deflections would naturally spread out and delay its COSMIC RAY signal, making it visible for $\sim 2\times 10^{5}$ years. Scaling this up, we model a local population of these exceptionally bright, narrow-JET transients within the \text{Greisen--Zatsepin--Kuzmin} (GZK) horizon. For a local volumetric rate of $\dot n_0\simeq4\times10^{-8}\ {\rm Mpc^{-3}\,yr^{-1}}$ and a JET half-opening angle of $0.8^\circ$, we estimate $\simeq3-7$ UHECR excesses across the sky at any given time. Varying the JET opening angle, GZK volume, and visibility time results in a broader range of excess values. It is possible to test this hypothesis by comparing the population predictions against existing and upcoming UHECR anisotropy data obtained by the Pierre Auger Observatory and the Telescope Array.
[abstract 3 / 43] Wow! (score: 7) - Title: Centaurus A: Opportunities to unveil particle acceleration with the CTAOAuthors: Cainã de Oliveira, Edivaldo Moura Santos,Comments:Subjects: astro-ph.HECreated: 2026-10-05; Updated: 2026-10-06; Datestamp: 2026-10-06
As the nearest RADIO GALAXy, Centaurus A (Cen A) has been observed across multiple wavelengths and over a broad range of angular scales, providing valuable insights into the functioning of RADIO GALAXies. However, despite being a known source of gamma rays, the physical mechanisms responsible for these high energy emissions remain unclear. In this study, we explore the capabilities of the Cherenkov Telescope Array Observatory (CTAO) to provide insights into the origin of the gamma-ray emission from Cen A. Using simulated observations based on the CTAO Instrument Response Functions (IRF) for the Alpha Configuration of telescopes, we investigate both the spectral and morphological domains to assess the observatory's potential to constrain competing models of particle acceleration in the kiloparsec-scale JET and the Southern Giant Lobe. For the JET, we explore CTAO observations with t=50 and 200h for different leptonic and hadronic origin scenarios for the very-high-energy gamma-ray emission. We show that longer observation campaigns (t=200h) would probe the presence of hard spectral components extending to tens of TeV. Morphological simulations demonstrate that CTAO can resolve the extended gamma-ray emission along the JET, discriminating between point-like and Gaussian spatial models within t=50h, assuming a known background model and an optimistic zenith angle $\vartheta=$20°. Under similar hypotheses, we studied the Giant Lobes evaluating both diffuse and filamentary emission templates for the S1 region detected by FERMI-LAT. We found that CTAO-South can be sensitive to hadronic scenarios with proton energies extending beyond 10 TeV, for the Alpha Configuration and $\vartheta=$20°. Overall, our results indicate that CTAO observations of Cen A can provide a decisive step toward unveiling the mechanisms driving the high-energy emission and particle acceleration in RADIO GALAXies
[abstract 4 / 43] Yes (score: 6) - Title: Photon Ring Astrometry I: A Simple Spin Measurement Technique for High-Resolution Images of M87*Authors: Delilah E. A. Gates, Dominic O. Chang, Aaron Held, Daniel C. M. Palumbo,Comments: 16 page, 7 figures, 1 table. v2: Modifications to match journal versionSubjects: astro-ph.HE gr-qcCreated: 2026-10-02; Updated: 2026-10-06; Datestamp: 2026-10-06
The supermassive BLACK HOLE M87* is a target for future horizon-scale imaging that will resolve the first lensed (${n}~{=}~{1}$) sub-image of the photon ring. In this work, we identify a concrete observable---the displacement between the centers of the ${n}~{=}~{1}$ photon-ring sub-image and the direct image. Assuming that the observed large-scale JET of M87 is aligned with the black-hole spin axis, we separate the relative position of the photon ring into components parallel and transverse to the projected spin axis. We show that the parallel shift is primarily determined by inclination and emission radius, while the transverse shift is tightly correlated with inclination and spin. We demonstrate these effects both in a simple geometric model (to explain the underlying physics) and in {general-RELATIVISTIC MAGNETohydrodynamics} simulations with MAGNETically arrested disks (to provide realistic instantiations). We find that a relative astrometric resolution of ${\lesssim}~{0.1\;μ\rm{as}}$, achievable by the proposed Black Hole Explorer mission, is sufficient to constrain the spin to better than 9\% if the accretion flow is prograde, 25\% if the flow is retrograde, or 24\% if the direction of the flow is undetermined. More generally, this identifies photon-ring astrometry as a promising method to constrain the underlying spacetime geometry without relying on geometric modeling of the observed emission.
[abstract 5 / 43] Yes (score: 6) - Title: Radiation Reaction in Relativistic Magnetized Shocks of Neutron Star MagnetospheresAuthors: Arno Vanthieghem, Amir Levinson,Comments: 15 pages, 11 figures, 1 tableSubjects: astro-ph.HE physics.plasm-phCreated: 2026-10-04; Updated: 2026-10-06; Datestamp: 2026-10-06
The steepening of fast MAGNETosonic waves in the inner MAGNETospheres of MAGNETars can produce monster shocks, whose precursor emission may account for fast radio bursts (FRBs). For sufficiently bright bursts, particles crossing the shock radiate their energy within a single gyration period, raising the question of how radiation reaction affects the shock structure and its coherent emission. We investigate strongly cooled, RELATIVISTICally MAGNETized shocks using a stationary multifluid model generalized to include the Landau-Lifshitz radiation-reaction force, together with particle-in-cell simulations of monster-shock dynamics. We show that the kinetic-scale shock transition is governed by only two dimensionless parameters: the Alfvénic Mach number and a cooling parameter $τ$ that measures radiative losses over a gyration period. Coherent precursor emission is triggered above a critical Mach number that increases with $τ$, at which the beam dynamics becomes chaotic. Above this threshold, radiative cooling shifts the peak frequency of the precursor to higher values, scaling as $τ^{2/7}$. Remarkably, monster shocks remain far above the emission threshold even under strong radiative cooling. Radiation reaction therefore does not quench the precursor emission; instead, it primarily shifts the spectral peak into the kinetic regime. The luminosity of the precursor wave is determined solely by the luminosity of the driving kHz wave and the conversion efficiency, $ε_X\sim 10^{-3} - 10^{-2}$.
[abstract 6 / 43] Yes (score: 5) - Title: Limit on high energy neutrino emission from Abell 119 using IceCube 10-year muon track dataAuthors: Sri Devaki Meduri, Shantanu Desai,Comments: 17 pages, 3 figures. Accepted for publication in Astroparticle PhysicsSubjects: astro-ph.HE astro-ph.COCreated: 2026-10-05; Updated: 2026-10-06; Datestamp: 2026-10-06
We carry out a search for high energy muon neutrino emission from the galaxy cluster Abell 119, motivated by a recent tentative detection of GeV gamma-ray emission from this cluster using the FERMI-LAT telescope, which hinted at a hadronic origin. For this purpose, we used the 10-year muon track data from 2008-2018, provided by the IceCube Collaboration and implement the unbinned maximum likelihood method. We do not find any statistically significant excess and the observed value of the test statistic is consistent with a null result. We then obtain upper limits (at 90\% confidence level) on the differential muon neutrino energy flux from this cluster, whose value is equal to $1.2 \times 10^{-9}~\mathrm{GeV}~\mathrm{cm}^{-2}~\mathrm{s}^{-1}$ at a pivot energy of 100 TeV, after assuming a neutrino spectral index of 2.0. The neutrino flux expected under the hadronic interpretation is, however, approximately an order of magnitude smaller than our flux limit, and hence the hadronic model cannot be ruled out based on our upper limit. Among the next generation neutrino detectors, IceCube-Gen2 and TRIDENT neutrino detector should be able to confirm or rule out a hadronic origin for the gamma-ray emission in Abell 119 with 10 years of exposure.
[abstract 7 / 43] Yes (score: 4) - Title: Impact of Cosmic Ray Acceleration on the Early Evolution of Bow Shocks around Massive Runaway StarsAuthors: Keito Watanabe, Stefanie Walch, Tim-Eric Rathjen, Jonathan Mackey, Pierre Nürnberger, Philipp Girichidis,Comments: Version 2: updated after referee comments. 24 pages, 25 figures (5 figures in Appendix). Accepted in A&ASubjects: astro-ph.HECreated: 2026-10-04; Updated: 2026-10-06; Datestamp: 2026-10-06
Bow shocks generated from the interaction of winds from massive runaway stars with the interstellar medium have been shown to be prominent particle accelerators through recent $γ$-ray and radio SYNCHROTRON observations. Here, we study particle acceleration from bow shocks by conducting 3D ideal COSMIC RAY MAGNETohydrodynamic simulations in the advection-diffusion limit. We use the Eulerian grid-based code FLASH, where stellar winds are injected through tabulated wind velocities and mass loss rates. We implement a gradient-based shock detection algorithm to resolve the shocked regions where the CRs are injected dynamically. Simulations are performed for different values of the CR diffusion coefficient and star velocities within an ISM-like environment up to 500 kyr to showcase the impact of dynamical CR injection on the early evolution of the wind-driven bow shock. With a simplified spectral model in post-processing, we calculate the expected upper limits of $γ$-ray and SYNCHROTRON emission and compare with those from current observations. We observe that variations of CR diffusion rates can strongly dictate the morphology of the bow shock and the overall $γ$-ray and radio SYNCHROTRON luminosity due to the balance between the CR injection efficiency and diffusion. Our results are underestimated as compared to current observations even with an overestimated particle acceleration primarily due to weaker wind luminosities and lack of stellar MAGNETic fields in our model. We conclude that CR acceleration, with varying CR diffusion rates, may substantially affect the morphology of wind-driven bow shocks and their non-thermal emission, if there is efficient particle acceleration in the forward shock. [abridged]
[abstract 8 / 43] Yes (score: 4) - Title: Horizon-scale intensity and POLARIZATION images of rotating Konoplya-Zhidenko BLACK HOLEs with thick accretion flowsAuthors: Bing-Bing Chen, Chen-Yu Yang, Guo-Ping Li, Xin-Yun Hu,Comments: 24 pages, 8 figuresSubjects: gr-qc astro-ph.HECreated: 2026-10-03; Updated: 2026-10-06; Datestamp: 2026-10-06
We investigate the shadow and POLARIZATION images of a Konoplya--Zhidenko rotating non-Kerr BLACK HOLE surrounded by a geometrically thick and optically thin accretion flow. The accretion flow is described by an analytical ballistic approximation accretion flow model. The numerical results show that the shadow image exhibits two main features, an outer bright ring and an inner dark region. The former corresponds to higher-order images, while the latter is associated with photon capture by the BLACK HOLE. Increasing the deformation parameter $η$ does not significantly change the overall shape of the higher-order images, but it enlarges their size. Increasing either the spin parameter $a$ or the observer inclination angle $θ_o$ enhances the asymmetry of the higher-order images and makes the intensity on the left side much larger than that on the right side. This behavior is associated with frame dragging and the RELATIVISTIC Doppler effect. In the POLARIZATION images, the degree of linear POLARIZATION is much smaller in the higher-order image region than in other regions, and the POLARIZATION vectors extend over the whole image plane. Within the framework used in this work, these results illustrate how the spacetime geometry and near-horizon accretion dynamics jointly influence the intensity and POLARIZATION images.
[abstract 9 / 43] Yes (score: 4) - Title: The Virgo Cluster as a Case Study for Ancient Cosmic Ray Halos in Radio and X-raysAuthors: Philip F. Hopkins, Emily M. Silich, Jack Sayers, Sam B. Ponnada, Isabel S. Sands,Comments: 13 pages, 5 figures. Submitted to the Open Journal of Astrophysics. Comments welcome. The companion case study of Perseus is https://arxiv.org/abs/2605.08349Subjects: astro-ph.HE astro-ph.CO astro-ph.GACreated: 2026-10-02; Updated: 2026-10-06; Datestamp: 2026-10-06
Virgo is the nearest cool core (CC) galaxy cluster, and is archetypal of the class of X-ray weak CCs. Despite the X-ray continuum implying a large cooling rate ($\gtrsim 10\,{\rm M_{\odot}\,yr^{-1}}$), measurements of cooler gas phases, dust, and STAR FORMATION show almost no cooling outside the M87 nucleus. It is also known that M87$^{\ast}$ is a prodigious source of COSMIC RAY (CR) leptons observed in radio and $γ$-rays, and recent radio observations have shown that the M87 radio halo is low-frequency and its spectral index steepens rapidly away from the injection region+JETs, consistent with an aging, low-energy CR population. We demonstrate that coupling X-ray and radio to newer Faraday rotation limits on the MAGNETic field, this implies the CRs within the CC radius ($\lesssim 40$kpc) must contribute significantly to the total pressure and soft X-ray emission, through a combination of Coulomb heating the gas and inverse-Compton (IC) scattering microwave background photons to $\sim$keV. We show this can explain the apparent correspondence between JET/radio power and X-ray cooling luminosity, and why the X-ray inferred cooling rate appears much larger than otherwise observed. This would also explain why the central X-ray inferred metallicity at $\lesssim 10\,$kpc appears to be suppressed relative to the UV/optical inferred metallicity (in a wavelength-dependent manner). Compared to more extreme radio+X-ray sources like Perseus, we find the observations require a softer 'escaping' CR spectrum (escaping or accelerated outside $\gtrsim 1\,$kpc from M87$^{\ast}$).
[abstract 10 / 43] Yes (score: 4) - Title: Polarimetry of Black Hole Spin and Axisymmetric Emission GeometryAuthors: Vadim Bernshteyn, Daniel C. M. Palumbo, Dominic Chang, Tintin Nguyen,Comments: 14 pages, 9 figuresSubjects: astro-ph.HECreated: 2026-10-02; Updated: 2026-10-06; Datestamp: 2026-10-06
The Event Horizon Telescope array has measured the average polarimetric spiral morphology of BLACK HOLE accretion disks using the so-called ``$β_2$'' coefficient. This measurement is dominated by the weakly lensed, direct ($n=0$, counting photon half-orbits) image of the disk, providing insight into MAGNETic field structure around the M87* BLACK HOLE. The future space-based Black Hole Explorer mission is expected to extend these capabilities, allowing for $β_2$ measurement of the strongly lensed $n=1$ image. In this paper, we explore the constraints $β_2$ measurements would impose on spacetime and plasma geometries using a semi-analytic conical emission model. We show that MAGNETic field orientation with respect to the emission cone qualitatively changes the dependence of $β_2$ modes on model parameters. For cone-aligned MAGNETic fields, we find that the leading-order theoretical prediction from equatorial emitters of $β_{2,\, n=0} \approxβ_{2,\, n=1}^*$ is the dominant trend even in off-equatorial models. Specifically, we show $\arg(β_{2,\, n=0}\,β_{2,\, n=1}^*) \approx 4χ$, where $χ$ is the angle determining in-cone MAGNETic field orientation. We also find that $\arg(β_{2,\, n=0}β_{2,\, n=1})$ minimizes the effect of MAGNETic field geometry while preserving a dependence on spin that may be used to measure spin direction. We find that observations of the photon ring's $β_2$ complement the constraint from direct image POLARIZATION, and can greatly constrain MAGNETic field structure even with an unknown external rotation measure. We also find that BLACK HOLE spin and emission cone opening angle would not be tightly constrained by $β_2$ alone, unless strong priors are placed on the MAGNETic field geometry.
[abstract 11 / 43] Yes (score: 4) - Title: Observed x-ray spectral indices support MAGNETic buoyancy sourced coronae in Seyfert ACTIVE GALACTIC NUCLEiAuthors: Ketevan Kotorashvili, Eric G. Blackman,Comments: 10 pages, 2 tables, 6 figures, submitted to Publications of the Astronomical Society of Australia (PASA)Subjects: astro-ph.HECreated: 2026-10-02; Updated: 2026-10-06; Datestamp: 2026-10-06
Standard radiation spectra modeling of ACTIVE GALACTIC NUCLEi like Seyfert galaxies typically involves tuning the relative contributions from an optically thick disc, optically thin corona, dust torus, and outflow by hand to match observations. The physics that quantifies this relative partitioning is not precisely understood. Here we make progress toward improving this understanding by testing the implications of a conceptual paradigm that the corona is supplied from below only by MAGNETic fields whose scales are large enough to escape turbulent shredding on their buoyant rise time. We use a generalized mean field accretion disc theory that includes both local radial angular momentum transport and angular momentum transport into a corona. We then use previous numerical simulations of MAGNETized turbulent accretion disc energy spectra to connect the fraction of disc MAGNETic energy that would escape to the fraction of coronal to total luminosity. Without explicitly calculating detailed particle acceleration and radiative processes, we assume that the disc radiation spectrum is thermal and the coronal radiation spectrum is a power law. We then show that the aforementioned paradigm for corona formation constrains the allowed x-ray power law index to a narrow range which agrees with observations. For the three AGNs studied here the predicted mean photon index is $\overlineΓ=1.76$, consistent with the mean observed value of $\overlineΓ_{\rm obs}=1.73$, bolstering confidence in the paradigm.
[abstract 12 / 43] Yes (score: 4) - Title: Broadband radio continuum and host galaxy properties of extremely inverted spectrum compact RADIO GALAXiesAuthors: Mukul Mhaskey, Barenya Dev, Aritra Basu, Helmut Meusinger, Surajit Paul, Matthias Hoeft,Comments: Accepted for publication in Astronomy and AstrophysicsSubjects: astro-ph.GACreated: 2026-10-05; Updated: 2026-10-06; Datestamp: 2026-10-06
We present broadband radio continuum spectra spanning 0.15-8 GHz for a sample of ten Extremely Inverted Spectrum Extragalactic Radio Sources (EISERS), selected from narrowband, low-frequency surveys below 1.4 GHz. In these surveys, EISERS show unusually steep low-frequency spectral indices, approaching or exceeding the SYNCHROTRON self-absorption (SSA) limit of $α$= +2.5, expected for homogeneous SYNCHROTRON sources. We have performed follow-up quasi-simultaneous radio observations of these sources using uGMRT (0.150-1.4 GHz) and VLA (1.0-8.0 GHz). The new observations provide improved frequency coverage and consistent flux calibration across both the optically thick and optically thin spectral regimes. We find that the spectral slopes of EISERS in optically thick regime are flatter than the two frequency spectral indices obtained using TGSS and WENSS and lie in the range +1.6 to +3, suggesting that heterogeneous survey data can introduce biases through flux-scale offsets, intrinsic variability of these compact sources and diverse angular resolutions between surveys. We modelled the broadband radio spectra as SYNCHROTRON emission affected by SYNCHROTRON self-absorption and subsequently modified by free-free absorption in an external ionised medium. The estimated physical parameters based on the best-fits indicate that the MAGNETic fields and thermal electron densities are similar to the general class of peak spectrum sources, with $B_{SSA}$ spanning over a large range of values from 20 mG to 8 G and $n_{e} \sim 29-128{cm}^{-3}$. Optical and infrared analysis further indicates that the EISERS are preferentially associated with dusty starburst galaxies, composite starburst-AGN systems, or obscured AGN embedded in dense circumnuclear environments, supporting a scenario in which at least a fraction of these sources represent young or environmentally confined radio AGN.
[abstract 13 / 43] Yes (score: 4) - Title: Three-dimensional MAGNETic RECONNECTion in unipolar regions. A case study of coronal bright points in the SunAuthors: D. Nóbrega-Siverio, F. Moreno-Insertis, A. S. H. To,Comments: Accepted in A&A, 14 pages, 6 figuresSubjects: astro-ph.SRCreated: 2026-10-05; Updated: 2026-10-06; Datestamp: 2026-10-06
Magnetic RECONNECTion is a fundamental mechanism underlying the heating and a wide variety of eruptive phenomena in the solar atmosphere; however, characterizing its 3D aspects remains challenging. Our aim is to understand how 3D MAGNETic RECONNECTion in unipolar regions drives localized heating and plasma ejections. To this end, we used a self-consistent 3D radiation-MHD simulation of a coronal bright point (CBP) performed with the Bifrost code. We focused on localized, intense heating events and upflows near a unipolar CBP footpoint associated with its parasitic polarity. 3D RECONNECTion diagnostics were carried out using the parallel electric field and its integral along MAGNETic field lines. We then compared the resulting upflows with spectroscopic observations from Hinode/EIS. We find recurrent episodes of 3D MAGNETic RECONNECTion without nulls at the footpoints of loops rooted near the CBP's parasitic polarity. A detailed analysis of one representative event places the RECONNECTion region at heights z=[1.0,2.5] Mm, within a predominantly vertical MAGNETic field with localized concentrations of electric current. The dissipation of these currents efficiently heats the plasma to about 2 MK and produces strong gas-pressure gradients that drive upflows of a few tens of km/s. Blueshifts observed with Hinode/EIS near the parasitic polarity of an observed CBP are consistent with this scenario. The recurrence of these RECONNECTion events are essential for heating CBP loops to million-degree temperatures. This form of 3D RECONNECTion may operate more generally in the solar atmosphere, dissipating MAGNETic stress around strong flux concentrations and contributing to heating in apparently unipolar regions. The resulting pressure-driven upflows offer an indirect spectroscopic diagnostic of localized RECONNECTion heating, which future observations with MUSE and Solar-C will be able to test.
[abstract 14 / 43] (score: 3) - Title: FastQSL 2: A Comprehensive Toolkit for Magnetic Connectivity AnalysisAuthors: Jun Chen, Thomas Wiegelmann, Li Feng, Chaowei Jiang, Rui Liu,Comments: 18 pages, 6 figuresSubjects: astro-ph.SRCreated: 2026-10-05; Updated: 2026-10-06; Datestamp: 2026-10-06
We present a new version of FastQSL for locating quasi-separatrix layers (QSLs) -- regions characterized by strong MAGNETic connectivity gradients, preferential current buildup, and subsequent MAGNETic RECONNECTion. This version now supports spherical coordinates, utilizing a second spherical coordinate system for tracing MAGNETic field lines around the polar regions. This approach completely resolves the singularity problem at the two poles. Furthermore, our code accommodates arbitrary mesh shapes for output, can provide both MAGNETic field and electric current density on the mesh, and can save the traced MAGNETic field lines. We suggest using $Q_\mathrm{local}$ calculated through a localized mapping to locate (quasi-)separators. By quickly and accurately outputting the footpoint coordinates of MAGNETic field lines, FastQSL can be used to derive the two key parameters used for modeling solar wind speed and slip-squashing factors for the case of zero boundary flow. Compared with the first version, FastQSL 2 achieves significant improvements in terms of application scope.
[abstract 15 / 43] (score: 3) - Title: Mapping Gas Accretion and Stellar Kinematics to Sub-kiloparsec Scales in NGC 4696 with JWST/NIRSpecAuthors: Mathieu Marquis, Julie Hlavacek-Larrondo, Olivia Pereira, Michael Reefe, Hyunseop Choi, Jorge Barrera-Ballesteros, Benjamin Vigneron, Ming Sun, Rebecca E. A. Canning, Gregory Taylor, Loïc Albert, Francesco D'Eugenio, Megan Donahue, Andrew C. Fabian, Gary J. Ferland, John S. Gallagher, Marie-Lou Gendron-Marsolais, Pierre Guillard, Minghao Guo, Nina Hatch, Ralf Kotulla, Yuan Li, Roberto Maiolino, Allison Man, Michael A. McDonald, Brian R. McNamara, Valeria Olivares, Marine Prunier, Christopher S. Reynolds, Carter Rhea, Annabelle Richard-Laferrière, Helen R. Russell, Philippe Salomé, Prathamesh Tamhane, Auriane Thilloy, Grant R. Tremblay, G. Mark Voit, Stephen A. Walker,Comments: Submitted to ApJ and revised in response to referee comments (36 pages, 23 figures)Subjects: astro-ph.GA astro-ph.HECreated: 2026-10-02; Updated: 2026-10-06; Datestamp: 2026-10-06
We present JWST/NIRSpec IFU spectroscopy of the central $618\times618$ pc$^2$ ($\sim3''\times3''$) of NGC 4696, the BCG in the Centaurus cluster. Leveraging the $\sim0.1''$ ($20.6$ pc) pixel size of JWST, we resolve a compact circumnuclear rotating disk (radius of $\sim120$ pc) traced by Pa$α$ and H$_2$ 1$-$0 S(1) emission, which allows a reassessment of the AGN position based on the kinematic centre of this disk. A central Pa$α$ velocity dispersion reaching $σ\sim449$ km s$^{-1}$ implies a SMBH mass of $\sim10^9$ M$_\odot$, corresponding to a sphere of influence of $r_\mathrm{inf}\sim60$ pc, resolved by our observations. Position-velocity diagrams reveal an increase from $\sim-200$ to $\sim600$ km s$^{-1}$ on scales of $\sim150$ pc (a gradient of $4.7$ km s$^{-1}$ pc$^{-1}$) and an accretion rate of $\sim18$ M$_\odot$ yr$^{-1}$ feeding the CND. The Pa$α$ emission shows a double-component in the core, with a high-dispersion redshifted component reaching $σ\sim600$ km s$^{-1}$. In contrast, MUSE H$α$ observations covering the $\sim10$ kpc-scale filamentary structure recover only weak velocity gradients ($\lesssim150$ km s$^{-1}$) within $\sim300\times300$ pc$^2$ and do not resolve the disk due to larger PSFs and pixel sizes. ALMA CO(2-1) data reveal only compact molecular clumps within a $\sim410\times410$ pc$^2$ region, with no extended counterpart to the structures traced by Pa$α$ and H$_2$ 1$-$0 S(1). Stellar kinematics show a smooth velocity field and broad dispersion profile, clearly decoupled from both the multiphase gas and the hot ICM probed by XRISM. These results provide a direct, spatially resolved view of gas dynamics within the inner few hundred parsecs, demonstrating the power of JWST/NIRSpec to probe SMBH feeding.
[abstract 16 / 43] (score: 3) - Title: Phase-Resolved Ultra-High-Energy Emission Defines an Energetic Boundary for Compact-Object Engines and Dense-Matter StructureAuthors: Marlon M. S. Mendes, Cesar H. Lenzi,Comments:Subjects: astro-ph.HECreated: 2026-10-02; Updated: 2026-10-06; Datestamp: 2026-10-06
We show that phase-resolved ultra-high-energy emission from LS I \(+61^\circ303\) defines a critical energetic boundary linking the compact-object engine, circumstellar interaction depth, and dense-matter structure. Combining the GeV--TeV--UHE spectral transition with an orbital acceleration--transparency sieve and branch-resolved stellar sequences for 116 certified EoS, we find that the measured \(25\)--\(100\) TeV component remains energetically viable for all 116 canonical-mass EoS and therefore does not discriminate among them. EoS discrimination arises only in the deliberately more demanding pure-hadronic \(>1\) TeV stress-test construction: at 2.0 kpc and \(1.4\,M_\odot\), this boundary gives \(I_{45,\rm crit}=1.5504\), with 82 of 116 EoS satisfying the energetic condition at\(\dot P_{\rm ref}=3\times10^{-15}\,{\rm s\,s^{-1}}\). A separately applied tidal diagnostic, \(Λ_{1.4}\leq580\), is satisfied by 43 EoS, with nine satisfying both conditions. These models span several microscopic classes but occupy a narrow structural region, indicating structural overlap rather than selection of a unique EoS family. A separate GeV power-budget test requires \(\dot P_{\rm rot}\gtrsim 5.65\times10^{-14}f_Ω\,{\rm s\,s^{-1}}\) at 2.0 kpc. For \(f_Ω\sim1\), the source lies well above the UHE crossing and the EoS discrimination disappears. The UHE observation therefore identifies the engine--environment regime in which differences in neutron-star structure can become observationally discriminating, rather than defining a universal dense-matter selector.
[abstract 17 / 43] (score: 3) - Title: Evidence for plasmoid formation related to a hot UV burst in the solar atmosphereAuthors: Mats Ola Sand, Luc Rouppe van der Voort, Souvik Bose, Daniel Nobrega-Siverio, Jonas Thoen Faber, Reetika Joshi, Ignasi Josep Soler Poquet,Comments: Accepted for publication in A&A. Includes links to movies associated with figuresSubjects: astro-ph.SRCreated: 2026-10-02; Updated: 2026-10-06; Datestamp: 2026-10-06
Magnetic RECONNECTion in the solar atmosphere drives energetic phenomena such as Ellerman bombs, UV bursts, and surges. We used coordinated observations from the Swedish 1-m Solar Telescope (SST), IRIS, SDO, and the Hinode/X-ray Telescope (XRT) to analyze an active region with strong MAGNETic flux emergence. This region displayed long duration UV burst activity, occurrence of multiple Ellerman bombs, and recurrent ejection of surges. Chromospheric imaging show sthe presence of a dome-like structure that overarched the region where MAGNETic flux was emerging. The curved chromospheric fibrils were closely associated with bright and similarly curved extensions from a UV burst in the IRIS 1400 A channel. We observed an episode of formation of a bright sheet along the curved fibrils in H-beta that subsequently fragmented into plasmoid-like blobs with peak emission at a Doppler offset of +43 km/s. IRIS Si IV lines in the same region show complex and non-Gaussian line profiles that display asymmetric extensions to high Doppler offsets. Some profiles have clear components with Doppler offsets in excess of 150 km/s on both sides of the nominal line center. The optically thin SDO/AIA channels, including 94 A, show intermittent and repeated occurrences of the burst. Emission measure and filter ratio analysis indicate that the burst is multi-thermal and can attain temperatures beyond 1 MK. AIA and Hinode/XRT observations reveal a localized EUV and soft-X-ray counterpart of the burst/dome system, supporting the presence of intrinsically multithermal plasma that reaches coronal, and likely multi-MK, temperatures.
[abstract 18 / 43] (score: 3) - Title: An End-to-End Numerical Framework for Tidal Disruption Events with AthenaKAuthors: Hong-Xuan Jiang, Mengqi Yang, David A. Velasco-Romero, Fangyuan Yu, Jing-Ze Xia, Xinyu Li, Yosuke Mizuno,Comments: 29 pages, 18 figures, accepted by ApJS. Code available at https://github.com/HongxuanJiang/athenak-transientsSubjects: astro-ph.IM astro-ph.HECreated: 2026-10-05; Updated: 2026-10-06; Datestamp: 2026-10-06
In a tidal disruption event (TDE), a BLACK HOLE (BH) tears apart a star, whose bound debris returns over many orbits to form an accretion disk. We present a framework built on the GPU-accelerated finite-volume code \texttt{AthenaK} that follows these stages in a single simulation with self-gravity throughout. We extend \texttt{AthenaK} with a moving frame, restart remapping between domains, an adaptive-mesh multigrid Poisson solver, a tabulated hydrogen--helium equation of state including recombination, a dual-energy update for the cold supersonic debris stream, a moving BH potential with excision, and localized adaptive time stepping (LAT), which speeds up the production run more than threefold. Each component is validated separately and in combination: the gravity solver maintains an isolated Lane--Emden sphere to a density error of $2.0\times10^{-3}$ over 16.3 dynamical times, and dual-energy recovery reduces the pressure error of a Mach $7.75\times10^7$ entropy wave from 15.7 to $4.0\times10^{-12}$. We demonstrate the framework with a Newtonian $β=1$ disruption of a $1\,M_\odot$, $1\,R_\odot$ star by a $10^3\,M_\odot$ BH. The debris has the expected energy spread, insensitive to the self-gravity update interval, splits evenly into bound and unbound material, and yields a fallback rate approaching $t^{-5/3}$ at late times. At the pericenter nozzle, the thermal energy gained in the high-resolution run matches the vertical kinetic energy lost to within 6\%, whereas the fiducial run, with 4--8 times coarser cells, overheats the thinnest early stream through numerical dissipation. Their heating agrees to 10\% once the returning stream thickens. Multifrequency LTE post-processing produces synthetic images and luminosities.
[abstract 19 / 43] (score: 3) - Title: The fading superorbital clock of Hercules X-1 in its 2025--2026 extended low stateAuthors: Zhenxuan Liao, Xinrui Tie, Yufeng Chi, Guanjun Lin,Comments: 13 pages, 8 figures. Submitted to MNRAS; under revision following peer reviewSubjects: astro-ph.HECreated: 2026-10-03; Updated: 2026-10-06; Datestamp: 2026-10-06
We present two decades of X-ray monitoring of the eclipsing accreting pulsar Hercules X-1 with \textit{FERMI}/GBM, \textit{SWIFT}/BAT and \textit{MAXI}/GSC, centred on the extended low state (ELS) that began in 2025 May (the first such event in 22 years) and is still ongoing at the time of writing, $\sim$480~d after its onset. The 35-d superorbital clock does not simply stop in the ELS; it fades. The surviving modulation stays phase-locked to the pre-ELS clock until the flux of the main high state (the bright phase of the 35-d cycle) has decayed to a few per cent of its normal level. The in-phase coherence is then lost, around 2026 January--March. We classify the pre-ELS pulse-frequency history into three torque states: spin-up, spin-down and flat. The spin derivative correlates positively with the main-high hard X-ray flux (Pearson $r\simeq0.7$), and the ELS hosts the longest sustained spin-down of the record, $\dotν\approx-4.7\times10^{-13}$~Hz~s$^{-1}$ over the $\gtrsim$380~d of \fer/GBM coverage. The 8--50 keV pulse-profile morphology is statistically indistinguishable across the torque states at fixed superorbital phase, and the shape parameters show no secular drift over the 18-yr record. These results show that the precessing warped accretion disc keeps its rhythm while the pulsar fades from direct view: the clock keeps its phase, the torque keeps tracking the accretion flux, and the beam keeps its shape. No free precession of the neutron star is required by the current monitoring data.
[abstract 20 / 43] (score: 3) - Title: Measured energy exchange in coronal hole solar wind from its solar origins to the heliosphereAuthors: Yeimy J. Rivera, Alin R. Paraschiv, Samuel T. Badman, Alberto M. Vasquez, Federico A. Nuevo, Ryan J. French, Momchil Molnar, Roberto Susino, Zihao Yang, Marco Romoli, Richard A. Frazin, Michael L. Stevens, Stuart D. Bale, Deborah Baker, Jasper Halekas, Thomas A. Schad, Christopher J. Owen, Philippe Louarn, Jenna Samra, Giuliana de Toma, Daniela A. Lacatus, Giulio Del Zanna, Chad A. Madsen, Enrico Landi, Manolis K. Georgoulis, Amir Caspi, Éric Buchlin, Nour E. Raouafi, Luca Franci, Miho Janvier, Cooper Downs, Roberto Livi, Phyllis Whittlesey, Ali Rahmati, Davin Larson, Nikos Sioulas,Comments: The manuscript has been accepted to ApJSubjects: astro-ph.SR physics.plasm-ph physics.space-phCreated: 2026-10-03; Updated: 2026-10-06; Datestamp: 2026-10-06
Coordinated ground- and space-based remote observations are used to provide a comprehensive, multi-perspective view of the solar atmosphere that we connect with in situ measurements in the heliosphere centered around the April 8 2024 Total Solar Eclipse observed across North America. These near-contemporaneous, multi-wavelength datasets are used to directly derive the plasma parameters and compute an energy budget of a solar wind stream at its low-coronal birthplace (at an altitude of 1.05Rsun). The energy budget is also independently computed at and beyond the Alfvén surface from the in situ observations of the same stream. The total wave energy flux dominates the low-coronal budget (11 W m-2 Alfvén, 7 to 23 W m-2 in compressive MHD modes), while enthalpy (13 W m-2) and work done against gravity from 1.0Rsun (2.5 W m-2) make up the remainder. The total coronal energy budget is consistent with the total measured in situ by Parker Solar Probe if and only if compressive energy flux is included and attributed to the fast MAGNETosonic mode. Nearly all this thermal and wave energy is converted to ion heating, acceleration and gravitational potential energy within the Alfvén surface. The stream evolution is well-described as a thermal-pressure driven wind with additional energy deposited by MHD fluctuations. The observed evolution of the Alfvénic component of these fluctuations follows a near-dissipation-free curve below the Alfvén surface while deviating from it more strongly above this critical surface.
[abstract 21 / 43] (score: 3) - Title: SPHERE/ZIMPOL observations of the symbiotic system R Aquarii. II. Dynamics of the dust in the Mira wind and the Halpha gas in the JETAuthors: H. M. Schmid, E. Lagadec, J. Milli, C. Tschudi, J. Ma, N. Engler, J. L. Beuzit, A. Boccaletti, G. Chauvin, R. Claudi, S. Desidera, K. Dohlen, M. Feldt, R. Gratton, Th. Henning, M. Kasper, M. Langlois, F. Ménard, D. Mouillet, A. Vigan,Comments: 25 pages, 22 figures, accepted by Astonomy & AstrophysicsSubjects: astro-ph.SR astro-ph.GACreated: 2026-10-04; Updated: 2026-10-06; Datestamp: 2026-10-06
R Aqr is a resolved symbiotic Mira binary and a prototype target for the study of complex hydrodynamic processes including dust-driven mass loss, mass transfer, accretion, and JET outflows and the formation of strongly asymmetric structures. We investigate for R Aqr the central Halpha emission from the ionized gas and the POLARIZATION from scattering dust based on SPHERE/ZIMPOL maps with a resolution of about 25 mas (5 AU). Data for four epochs were taken, including the dust eclipse around 2021, to follow structural changes. The central Halpha gas traces the orbital motion of the hot component. The POLARIZATION from scattering dust shows interaction effects near the binary (<60 AU), including a flattened distribution in the orbital plane, corotating dust, and a reduction of the scattering signal during the dust eclipse. The POLARIZATION shows at >60 AU a steady outflow with about a dozen dust clouds, a few of which have a comet-like core and tail features. The dust velocity is about 20 km/s, and this is faster than for the CO gas measured with ALMA. Several prominent Halpha clouds also show scattering POLARIZATION because they are just partly ionized dust clouds from the Mira wind. We also found small faster-moving transient Halpha clouds, pointing to outflow instabilities and shocks. The observed angular shift of Halpha during the dust eclipse, can be explained by strong illumination changes from the hot component. At larger separation, the H$α$ clouds move faster (>100 km/s), in agreement with previous studies. This acceleration is probably a result of gas heating by photoionization and shocks, and the produced overpressure gives rise to the two well-known JET-like features expanding in polar directions. The presented R Aqr data are very useful to clarify the complex hydrodynamics taking place in AGB binaries.
[abstract 22 / 43] (score: 3) - Title: Pulsations and constraints on time lags in two distinct ULXs: NGC 5204 X-1 and NGC 55 ULX-1Authors: Sathyaprakash, Rajath, Middleton, M. J., Done, C,Comments: 25 pages and 24 Figures; comments welcomeSubjects: astro-ph.HECreated: 2026-10-04; Updated: 2026-10-06; Datestamp: 2026-10-06
The nature of ultra-luminous X-ray sources (ULXs) is shrouded in mystery as they're believed to be point sources with luminosities above the classical Eddington limit for a 10$M_{\odot}$ BLACK HOLE (BH), but generally fit into the classification tree of super-Eddington X-ray binaries. Studies of reverberation lags and lag-energy spectra provide some insight into the nature of viscous turbulence in optically thick, super-Eddington discs, and are useful in conjunction with modelling multi-wavelength spectra and covariance spectra. In this study, we focus on the timing properties of two classically distinct ULXs: NGC 5204 X-1 and NGC 55 ULX-1, both of which are known to emit RELATIVISTIC winds, as observed by modelling emission line spectra with photo-ionisation models such as SPEX, but are thought to be viewed at slightly different inclinations due to differences in the hardness-ratio of their X-ray continuum. Here, we perform an extensive timing study of the two ULXs to reveal new constraints on the accretion disc size scale and structure. We also perform an accelerated search for pulsations (including the correction for an orbital modulation of the signal) to discover significant spin-periodicities in both NGC 5204 X-1 and NGC 55 ULX-1 (at $> 3σ$ significance).
[abstract 23 / 43] (score: 3) - Title: Fast and Differentiable MHD Surrogate for Solar Wind using Neural OperatorAuthors: Prateek Mayank, Enrico Camporeale, Thomas E. Berger, Zhenguang Huang, Gabor Toth,Comments: 10 pages, 5 figuresSubjects: astro-ph.SR physics.flu-dyn physics.plasm-ph physics.space-phCreated: 2026-10-05; Updated: 2026-10-06; Datestamp: 2026-10-06
Global MAGNETohydrodynamic (MHD) simulations provide the complete plasma state of the heliosphere, but their computational cost limits applications requiring repeated model evaluations. We introduce SNOW (Solar Neural Operator for Wind), a fast and differentiable surrogate for global MHD solar wind. SNOW combines a rotational ballistic approximation, a spherical harmonic neural operator, and causal radial context to autoregressively propagate all eight MHD variables from 20 to 240 Rs through consecutive shell to shell transitions. Trained and evaluated using AWSoM simulations spanning a solar cycle, SNOW remains stable across the complete rollout. The model successfully reproduces the large scale plasma and MAGNETic field structures, including fast and slow wind streams, MAGNETic polarity sectors, vector orientations, fieldline connectivity, and bulk-flow structures. Additionally, the MAGNETic divergence and induction diagnostics remain comparable to the reference MHD solutions. The complete three-dimensional solution is generated in less than one second on a single GPU. These results demonstrate the feasibility of fast neural emulation of global MHD solar wind solutions while retaining physically meaningful plasma and MAGNETic field structure.
[abstract 24 / 43] (score: 3) - Title: Coherent radio bursts, polarity reversal, and quiescent emission from the M4V dwarf WW PsAAuthors: Jackson Mitchell-Bolton, Laura Driessen, Tara Murphy, Joshua Pritchard, Barnali Das, Richard Dodson, Martin Meyer, Jonghwan Rhee, Yuanming Wang,Comments: 14 pages, 7 figures, 1 table, accepted for publication in PASASubjects: astro-ph.SR astro-ph.HE physics.plasm-phCreated: 2026-10-05; Updated: 2026-10-06; Datestamp: 2026-10-06
Coherent radio emission from MAGNETically active M dwarfs is largely observed in two varieties: stochastic solar-like bursts and beamed, rotationally modulated emission including auroral pulses. Detailed monitoring of these stars is critical for probing the plasmas and MAGNETic fields driving the emission. We conducted a search for polarised radio emission from stars within 85 pc, covering $2.2\times10^4$ h of stellar dynamic spectra from the ASKAP Deep Investigation of Neutral Gas Origins (DINGO) survey. We report the discovery of coherent radio bursts from the M4V dwarf WW PsA. In addition to quiescent emission, we detect three long-duration ($\gtrsim$30 min) bursts, each ~100% circularly polarised, in 283.3 h of data. We also report a fourth burst in an epoch not covered by our search, detected using the VASTER pipeline. One of the bursts features a polarity reversal midway through, based on which we favour the electron cyclotron maser (ECM) mechanism over plasma emission. We tentatively propose the bursts are due to rotationally modulated ECM pulses of variable intensity. We infer the required physical properties of WW PsA, including a high obliquity $β= 74^{+6}_{-22}$ deg under an oblique rotator model.
[abstract 25 / 43] (score: 3) - Title: Stellarators Linking Axisymmetric Mirrors Part 1: Coil Design, MHD Equilibrium, and Physics MetricsAuthors: Rahul Gaur, Djin Patch, Robert Babin, Florian Hindenlang, Xu Chu, Tony Qian,Comments: 23 pages, 11 figuresSubjects: physics.plasm-phCreated: 2026-10-05; Updated: 2026-10-06; Datestamp: 2026-10-06
We present a computational design study of a stellarator-mirror hybrid concept, Stellarators Linking Axisymmetric Mirrors (SLAMs), in which an optimized poloidally omnigenous (OP or QI) stellarator serves as the rotational-transform-generating element that links long, axisymmetric (circular cross-section) MAGNETic mirrors. Starting from an OP precursor configuration obtained from the DESC omnigenity database, we construct hybrid coil sets for field period nFP = 2 SLAMs by separating the OP modular coils along the device midplane and inserting axisymmetric planar mirror coils into the resulting gap. Field-line tracing shows that nested vacuum flux surfaces survive this extrusion across a range of mirror-section lengths, with the cross-section qualitatively preserved at the point where the mirror is inserted. We use the field-line tracing data to map the shape of a surface and use the GVEC fixed-boundary solver to calculate an ideal MAGNETohydrodynamic (MHD) equilibrium and evaluate physics metrics such as the neoclassical transport proxy (eps_eff), the vacuum MAGNETic well (W), and the gyrokinetic heat fluxes (Q), providing a first-principles analysis of such concepts using modern stellarator analysis tools.
[abstract 26 / 43] (score: 3) - Title: Energy-independent X-Ray Polarization in 4U 1630-47 in the Intermediate State from Spectroscopy and PolarimetryAuthors: Elena Seifina, Lev Titarchuk, Paolo Soffitta, Lorenzo Marra, Fiamma Capitanio, Fabio Muleri, Anastasiia Emelianova,Comments: 17 pages, 13 figuresSubjects: astro-ph.HECreated: 2026-10-05; Updated: 2026-10-06; Datestamp: 2026-10-06
The IXPE mission enabled measurements of X-ray POLARIZATION in accreting binaries. The dependence of the X-ray POLARIZATION degree on the binary inclination and the optical depth of the emitting medium $τ_0$ are the new important tools in X-ray Astronomy. We analyzed the BLACK HOLE X-ray binary 4U~1630--47 as an example of one of the enigmatic sources in our Galaxy. We consider spectral and polarimetric observations of outburst episodes from 4U~1630--47 observed with the IXPE and the NICER. We carefully investigated a time interval of the IXPE observations during which 4U~1630--47 was in a single spectral state (the intermediate state) and found that the POLARIZATION degree did not change significantly during this time interval with the photon energy in the 2--8 keV range ($P\sim$ 6\%). We interpreted this energy independence behavior in $P(E)$ as a result of the Comptonization (up-scattering) of soft photons in the flat Compton cloud. We argued that the X-ray source broadband energy spectra can be reproduced by a physical model composed of the Comptonized component and iron-line ({\it Gaussian}) component. Spectral analysis using this model shows that during the intermediate state the 4U~1630--47 spectrum was characterized by a photon index $Γ\sim 2.5$ and the electron temperature $kT_e\sim ~9 ~{\rm keV}$. In fact, this approach allows one to easily find the half-optical depth $τ_0\sim 1.8$ of the Compton cloud in 4U~1630--47 applying the inclination $69\pm1^\circ$ and using the relation $(P,\cos(i),τ_0)$ when solving the full radiative transfer equation for a flat Compton cloud by an iterative method. This approach is also accompanied by the fact that the POLARIZATION degree is independent of the photon energy, which we demonstrate observationally, at least for 4U~1630--47 in the 2--8 keV range.
[abstract 27 / 43] (score: 3) - Title: Gravitational-wave background from supermassive BLACK HOLEs without merger trees: Tidally regulated mergers and direct inference from the NANOGrav 15 yr dataAuthors: Shin'ichiro Ando,Comments: 20 pages, 7 figuresSubjects: astro-ph.CO astro-ph.HE gr-qcCreated: 2026-10-05; Updated: 2026-10-06; Datestamp: 2026-10-06
We present a semi-analytic framework that computes the gravitational-wave background (GWB) from supermassive BLACK HOLE (SMBH) binaries by direct integration of an $N$-body-recalibrated extended Press-Schechter accretion kernel, bypassing Monte Carlo merger trees entirely. The calculation is resolution-free and fast enough to be sampled directly against pulsar-timing data with no emulator or precomputed model bank. Between halo accretion and black-hole binary formation, we couple the satellite's simulation-calibrated tidal mass loss continuously to Chandrasekhar dynamical friction. Satellites below a sharp, nearly redshift-independent mass-ratio threshold, $ξ\simeq 0.04$, are stripped faster than they sink and stall: their drag collapses onto the stellar core, and 38% of accreted satellites are unmerged by $z=0$. Combining this population model with per-binary stellar-hardening turnovers and eccentric spectra, we sample the five-parameter posterior directly against the NANOGrav 15 yr Hellings-Downs-correlated free spectrum, excluding the $15.8$ nHz bin, whose excess power a subsequent chromatic-noise reanalysis attributes to pulsar noise. The data prefer a black-hole mass normalization $+0.31^{+0.20}_{-0.23}$ dex above the locally calibrated black-hole-bulge mass relation, consistent with earlier indications that the nanohertz background is loud relative to local SMBH calibrations and robust to the delay model, merger kernel, local mass calibration, and its redshift evolution. The spectrum is compatible with, but does not require, eccentric binaries or dense stellar environments.
[abstract 28 / 43] (score: 2) - Title: Tests of General Relativity with Einstein TelescopeAuthors: Andrea Begnoni, Walter Del Pozzo, Matteo Pegorin, Joachim Pomper, Angelo Ricciardone,Comments: 30 pages, 9 figures, 4 appendices; v2: updated figures and discussion, typos corrected; matches the version published in JCAPSubjects: gr-qc astro-ph.CO astro-ph.HECreated: 2026-10-04; Updated: 2026-10-06; Datestamp: 2026-10-06
Gravitational wave signals from compact binary coalescences provide powerful and reliable probes of General Relativity. To date, the LIGO-Virgo-KAGRA collaboration has provided stringent consistency tests of General Relativity predictions. In this work, we present forecasts for how accurately General Relativity can be tested using third-generation ground-based interferometers, focusing on Einstein Telescope (ET) and binary BLACK HOLE mergers. Given the expected high detection rate, we use a Fisher matrix approach to simulate parameter estimation over large source catalogs, and jointly analyze events within a Bayesian hierarchical framework. We compare different ET configurations and forecast constraints on parametrized deviations of the inspiral post-Newtonian coefficients. Our results indicate that, within about four months of observations, ET could improve current LVK GWTC-3 bounds by roughly four orders of magnitude for the dipole radiation term and about two orders for higher-order coefficients. We further assess the number of detections required to confidently identify deviations from General Relativity at various post-Newtonian orders and for different detector configurations.
[abstract 29 / 43] (score: 2) - Title: The JET-shaped pipe morphology in planetary nebulae and core-collapse SUPERNOVA remnantsAuthors: Jessica Braudo, Noam Soker,Comments: Published in the Open Journal of AstrophysicsSubjects: astro-ph.HECreated: 2026-10-03; Updated: 2026-10-06; Datestamp: 2026-10-06
We compare images of core-collapse SUPERNOVA (CCSN) remnants (CCSNRs) and JET-shaped planetary nebulae (PNe) that have a narrow, faint zone extending from side to side, termed a pipe, with a hydrodynamical numerical simulation exploding a massive star with three pairs of JETs in the framework of the jittering JETs explosion mechanism (JJEM), and conclude that JETs shaped the pipes in these CCSNRs and PNe. We present two JET-shaped PNe with a pipe and three PNe with two opposite narrow JET-shaped lobes, and argue that in some cases the two opposite narrow lobes might merge to form one long, faint zone extending from side to side of the PN, namely, a pipe. From the qualitative similarity between the pipe morphology of the two CCSNRs we analyze and the pipe of the PNe, we suggest that JETs also shaped the pipe of these CCSNRs. We strengthen this conclusion with a three-dimensional hydrodynamic simulation that reproduces two opposite narrow lobes, similar to those observed in PNe with lobes. These lobes can merge later to form a pipe. This paper is another in a series that strengthens the case for the JJEM as the primary explosion mechanism of CCSNe by comparing CCSNR morphologies with those of JET-shaped PNe.
[abstract 30 / 43] (score: 2) - Title: Collisionless stationary states of a stratified plasma in an expanding MAGNETic tube with stochastic heatingAuthors: Luca Barbieri, Pascal Démoulin, Daniel Verscharen,Comments: 27 pages, 5 figures, accepted in Physics of PlasmasSubjects: astro-ph.SR physics.plasm-phCreated: 2026-10-05; Updated: 2026-10-06; Datestamp: 2026-10-06
We investigate the collisionless kinetic structure of the upper solar atmosphere in an expanding MAGNETic field. Building on established velocity-filtration models, we extend the stochastic multi-temperature framework developed in previous works by including MAGNETic-field expansion and MAGNETic-moment conservation. Stochastic heating generates a non-Maxwellian boundary distribution through the superposition of particle populations associated with different temperatures. We consider a stationary two-component plasma confined within an expanding MAGNETic flux tube and subject to gravity, self-consistent electrostatic interactions, the Pannekoek--Rosseland electric field, and MAGNETic-moment conservation. Starting from the Vlasov equation, we derive fully analytical expressions for the distribution functions, density, and parallel, perpendicular, and total temperature profiles. The combined conservation of energy and MAGNETic moment generates a loss-cone distribution, reducing the density relative to the unMAGNETized case and producing temperature anisotropy. For a single-temperature boundary, the competition between gravity and MAGNETic-moment conservation produces a maximum in the parallel temperature, for which we derive and numerically validate analytical scaling laws. With stochastic heating, gravitational filtering enhances the contribution of hotter populations at coronal heights, while MAGNETic-moment conservation amplifies the velocity-space anisotropy. Our analytical solution provides a collisionless benchmark for future kinetic models incorporating more realistic MAGNETic-field geometries, Coulomb collisions, and turbulent particle scattering.
[abstract 31 / 43] (score: 2) - Title: The ejected volume and drop statistics by bubble bursting in a sessile dropAuthors: Alfonso M. Ganan-Calvo,Comments: 12 pages, 8 figuresSubjects: physics.flu-dynCreated: 2026-10-03; Updated: 2026-10-06; Datestamp: 2026-10-06
A bubble bursting inside a drop resting on a substrate can eject JET droplets where a bubble at a bath would not. We compute how much liquid it ejects and how the ejected droplets are distributed in size. The volume ejected by the JET grows by more than an order of magnitude as the Bond number decreases from $0.5$ to $0.1$ and then saturates, and the larger the Bond number, the smaller the viscosity that suppresses ejection. At zero Bond number the substrate alone extends the ejection boundary to larger Ohnesorge numbers, contrary to expectation, and yet reduces the volume ejected at the same distance from it. Gravity sets how much liquid the JET carries, not how the JET fragments: scaled with its mean, the droplet-size distribution is independent of the Bond number and has an exponential tail, as for free hollow droplets. The simulations, built on a closed family of sessile equilibria, reproduce the measured velocity of the first droplet within 7\,\%, while the volumes emitted in experiments are eight to ten times those computed for the same geometry.
[abstract 32 / 43] (score: 2) - Title: Finding the evolutionary link between ULIRGs and RADIO GALAXiesAuthors: Ayisha Fida, Sumana Nandi, Mousumi Das, K. Rubinur, S. Shanbhog, Preeti Kharb, Barenya Dev,Comments: 28 pages, 65 figuresSubjects: astro-ph.GACreated: 2026-10-03; Updated: 2026-10-06; Datestamp: 2026-10-06
Ultraluminous infrared galaxies (ULIRGs) are the remnants of the major mergers of gas-rich galaxies. They are dusty systems and are extremely luminous in the infrared. Both starbursts and ACTIVE GALACTIC NUCLEus (AGN) activity supply power in these systems, but it is not clear how these two activities are related to the overall evolution of the merger remnant. Studies suggest that there may be an evolutionary link between ULIRGs and RADIO GALAXies. Radio observations of ULIRGs are a useful tool for understanding this evolutionary path as well as studying the energy contributions from starbursts and AGN. We perform a systematic census of these signatures in 38 ULIRGs using upgraded Giant Metrewave Radio Telescope observations and archival radio data. In the sample, 30 sources have enough frequency coverage to obtain their radio spectrum. Of these, 17 sources show a turnover frequency between 63 and 509 MHz and a spectral age variation from 0.009 to 44 Myr. Also, eight sources have extended structures with projected linear sizes varying from 0.7 to 11 kpc. Our results indicate that the primary energy source in these systems is the AGN rather than STAR FORMATION. The majority of the ULIRGs in our sample, particularly those in the post-merger stage, exhibit gigahertz-peaked spectrum or compact steep spectrum-like characteristics, suggesting that they are evolving into young RADIO GALAXies. We note that six sources with high STAR FORMATION activity show a low-frequency turnover and a smaller spectral age; we confirm these six sources host buried AGN. This study enables us to trace the evolutionary link between ULIRGs and RADIO GALAXies.
[abstract 33 / 43] (score: 2) - Title: Design of the Electron-Beam Collimator for the Electron-Ion ColliderAuthors: Andrii Natochii, Elke-Caroline Aschenauer, Jay Best, Alexei Blednykh, Xiaofeng Gu, Kuppan Gunavathi, Charles Hetzel, Christoph Montag,Comments: 26 pages, 12 figures, and 5 tablesSubjects: physics.acc-phCreated: 2026-10-03; Updated: 2026-10-06; Datestamp: 2026-10-06
The design and optimization of a beam collimator for the Electron Storage Ring (ESR) of the Electron-Ion Collider (EIC) are presented. The collimator must efficiently intercept stray beam particles while maintaining acceptable beam coupling impedance, surviving rapid accidental beam impacts, and withstanding steady-state beam-induced heating. An integrated design approach combining beam-loss tracking, electroMAGNETic-shower simulations, thermomechanical analysis, and impedance calculations is developed and benchmarked against published simulations and beam-impact experiments. A comparison of candidate absorber materials identifies Al2219-T62 as providing a favorable balance of beam-impact robustness, thermal and electrical conductivity, mechanical strength, and ultra-high-vacuum compatibility. For the ultimate ESR bunch charge of 28 nC at 10 GeV, the Al2219-T62 jaw remains below the adopted practical thermal-shock threshold for approximately 50 fully intercepted bunches and below the localized melting threshold for approximately 100 bunches under the reference impact conditions considered. These results provide an engineering input to the machine-protection requirements, for which a complete protection response within several machine turns is required. Optimization of the absorber-tip length yields a 70 mm tapered jaw that balances collimation performance, beam-impact robustness, and impedance. The resulting design maintains acceptable impedance margins and remains below both the yield and ultimate tensile strengths under a conservative 3.6 kW beam-induced heating scenario. The results establish a baseline ESR collimator design and a benchmarked methodology for evaluating collimator robustness in high-current electron storage rings.
[abstract 34 / 43] (score: 2) - Title: Measuring the Moving Lens Effect with Wide-Separation Lensed QuasarsAuthors: Yupeng Zhang, Shuxun Tian, Zhengxiang Li,Comments: 9 pages, 5 figuresSubjects: astro-ph.COCreated: 2026-10-04; Updated: 2026-10-06; Datestamp: 2026-10-06
The transverse motion of a gravitational potential induces frequency shifts in photons propagating through it, giving rise to the moving-lens effect and providing a probe of transverse peculiar velocities. Statistical evidence for this effect has recently been reported using cross-correlations between cosmic microwave background temperature maps and large-scale-structure tracers. Here, we investigate a complementary spectroscopic approach based on wide-separation lensed QUASARs, for which different lensed images probe distinct deflection geometries through a moving foreground lens. We focus on SDSS J1004+4112 and assess the differential redshift that could be measured from its broad emission-line spectra. Using an estimator that combines information across the line profiles, we perform Monte Carlo forecasts for C IV and C III] under an ELT-like configuration, considering photon noise only. For an assumed lens transverse velocity of $500\,{\rm km\,s^{-1}}$ and the orientation maximizing the signal, the expected differential redshift reaches $|Δz_{\rm ML}|\simeq6.7\times10^{-7}$. At an integration time of 40 hr, the joint photon-noise-limited precision is $σ_z\simeq2.5\times10^{-7}$. C IV dominates the constraint, while C III] provides only a modest additional improvement, and integrations of tens of hours reach the $10^{-7}$ precision regime. These results show that photon statistics alone can reach the characteristic moving-lens signal scale, although practical detectability will depend on controlling astrophysical and instrumental systematics.
[abstract 35 / 43] (score: 2) - Title: Large-Scale Stellar Bars and Nuclear Activity in Narrow-Line Seyfert 1 GalaxiesAuthors: Po-Chieh Yu,Comments: 19 pages, 8 figures. Accepted for publication in The Astrophysical JournalSubjects: astro-ph.GACreated: 2026-10-04; Updated: 2026-10-06; Datestamp: 2026-10-06
We present a statistical comparison between barred and unbarred narrow-line Seyfert 1 galaxies (NLS1s) to investigate the role of large-scale stellar bars in fueling AGN with low-mass BLACK HOLEs. From a parent sample of 492 NLS1s selected from SDSS and Pan-STARRS1 (PS1), we construct a PS1-resolved matched sample of 101 barred and 101 unbarred NLS1s, matched in redshift, inclination, and image quality. Unbarred NLS1s are modestly but consistently brighter than barred NLS1s in several optical AGN luminosity indicators, including $λL_λ(5100~A)$, broad H$α$, broad H$β$, narrow H$α$, narrow H$β$, and [O III]~$λ5007$, with typical offsets of $\sim 0.1$--$0.25$ dex; the broad H$α$ and narrow-line offsets are statistically significant, while the continuum and broad H$β$ offsets are marginal. Monte Carlo resampling and a Bayesian model support the same direction of offset. In contrast, the main narrow-line diagnostics, including [O III]/H$β$, O3N2, and the [S II]-based electron density, are statistically consistent between the subsamples, although barred NLS1s show a higher N2 ratio. Within the barred subsample, the bar strength parameter $e_{\max}$ shows a mild anti-correlation with the optical continuum and broad Balmer-line luminosities. These results indicate that large-scale stellar bars are not associated with enhanced instantaneous optical AGN luminosity. Instead, barred systems may experience more regulated or time-variable inner gas delivery, building circumnuclear gas reservoirs without necessarily increasing accretion power observed at the epoch traced by optical AGN emission.
[abstract 36 / 43] (score: 2) - Title: Generating Kolmogorov spectra and structure functions with a Rosenhead profile trefoil vortex knotAuthors: Robert M. Kerr,Comments:Subjects: physics.flu-dynCreated: 2026-10-04; Updated: 2026-10-06; Datestamp: 2026-10-06
Motivated by recent experimental observations by Matsuzawa et al. (2026) of colliding several vortex rings within a water tank, this paper extends a compact trefoil vortex simulation to later times and generates a persistent ==energy spectrum that obeys Kolmogorov scaling, together with other statistics characteristic of fully developed turbulence, including structure function scaling. This temporal extension uses a larger (4pi)3 periodic domain, with the improved compactness being achieved by the use of an algebraic Rosenhead vorticity profile, from which viscosity(nu)-independent finite energy dissipation is generated and pre-RECONNECTion convergence of nu1/4-dependent higher-order vorticity moments. These properties suggest, perhaps for the first time, how decaying Navier-Stokes simulations can generate fully-developed turbulent flow from an unforced initial state that is far from boundaries, thereby suggesting how further simulations at higher values of Re could be harnessed for experimental comparisons. Moreover, the exponents for the energy decay and the integral scale growth, E(t)~(t+t0)-10/7 and and ell(t)~(t+t0)2/7, follow those based upon preservation of the Loitsyanskii integral. On a related question, an integral scale growth rate ell that is close to the experiment rate of ellX~(t+t0)(0.16or1/7)is only obtained if the Fourier modes at the scale of the periodic domain are not considered.
[abstract 37 / 43] (score: 2) - Title: Grid Optimization for Wide Field Modulation CollimatorsAuthors: Steven E. Boggs,Comments: 13 pages, 9 figures, submitted The Astronomical JournalSubjects: astro-ph.IM astro-ph.HECreated: 2026-10-04; Updated: 2026-10-06; Datestamp: 2026-10-06
Wide-field localization of transient sources such as GAMMA-RAY BURSTs (GRBs) places new demands on the grid design of modulation collimators, whose usable field of view (FOV) is normally limited by self-vignetting. A grid slat thick enough to be opaque at the energies of interest also clips off-axis rays, shrinking the effective slit width and ultimately defining the FOV itself. Historical bigrid or rotating-modulation-collimator (RMC) designs have been designed with this trade-off as an unavoidable consequence of geometric optics. We explore whether the cross-sectional shape of the grid slats can be optimized for wide FOV applications. We derive a general transmission-function framework for a bigrid pair in terms of an effective slit width that depends on slat geometry and use it to compare four slat cross sections: the conventional rectangular slat, an idealized diamond profile, a hexagonal profile that approximates photochemical etching, and the circular wire grids of early X-ray astronomy. We show that for the same bigrid pitch and thickness, a diamond profile extends the FOV and eliminates clipping throughout most of the field. We also demonstrate that a hexagonal profile achievable with standard tungsten etching factors captures many of the benefits of the idealized diamond profile. Extending the analysis to the four-phase demodulation, we show that slat shape directly sets the extent of the resulting phase-space blind spots, and that the diamond profile removes them entirely across a target FOV where the rectangular baseline cannot. We further show that finite grid opacity is a largely separable effect. Leakage through the grid leaves the geometric blind-spot boundaries unchanged. These results identify slat cross-sectional shape as a design parameter that can substantially increase throughput and widen the blind-spot-free field of view of a wide-field modulation collimator.
[abstract 38 / 43] (score: 2) - Title: Lifshitz transition and MAGNETic superconductivity in flat band systemsAuthors: Sudeshna Pal, K. B. Yogendra, Madhuparna Karmakar, Rajesh Narayanan,Comments: 21 pages including references and appendixSubjects: cond-mat.str-el cond-mat.supr-conCreated: 2026-10-05; Updated: 2026-10-06; Datestamp: 2026-10-06
A Lifshitz transition is a class of non-symmetry-breaking transitions typically associated with metallic systems wherein the FERMI surface changes its connectivity as the chemical potential sweeps through a band extremum or a saddle point. The phenomenology naturally adapts itself to the superconducting state, where the object that reconstructs is the manifold of minimum quasiparticle energy rather than the FERMI surface. This paper concerns Lifshitz-type transitions in multi-band superconductors. Thus, we focus on the attractive Hubbard--Kondo model on the two-dimensional Lieb lattice, with classical core spins coupled to the itinerant electrons, by laying recourse to a real-space Bogoliubov--de Gennes mean-field theory and an analytic Green's function calculation. The competition between the Kondo and pairing channels yields a MAGNETic superconductor throughout, with $(π,π)$ order near half filling giving way to $(0,π)$ and then, at stronger Kondo coupling, to an incommensurate spiral $(0,q)$. In such a multiband superconductor hosting a flat band, we identify two inequivalent Lifshitz-type transitions. With the core spins decoupled (the Kondo coupling set to zero), the minimum energy contour deforms with chemical potential, a hole pocket about $M$ opening into a perfectly nested square at $μ=-2t$ and RECONNECTing into pockets about $Γ$; this nesting fixes where $(π,π)$ order sets in. At finite Kondo coupling, for certain chemical potential, the dimension of the manifold itself drops. We obtain it analytically for each MAGNETic order and show that only the spiral carries the minimum energy through zero, nucleating nodes and leaving a gapless MAGNETic superconductor, with clear signatures in the density of states and the spectral function.
[abstract 39 / 43] (score: 2) - Title: Turbulent Origin of the Edge Radial Electric Field Asymmetry between Favourable and Unfavourable Drift ConfigurationsAuthors: B. J. Frei, R. Bilato, W. Zholobenko, O. Grover, C. Angioni, M. Bergmann, P. Ulbl, F. Jenko, S. Rienäcker, L. Vermare, P. Hennequin, B. Labit,Comments: 44 pages, 27 figures, 2 tables. Submitted to Plasma Phys. Control. Fusion. Companion paper to B. J. Frei et al., Phys. Rev. Lett. 137, 035103 (2026)Subjects: physics.plasm-phCreated: 2026-10-05; Updated: 2026-10-06; Datestamp: 2026-10-06
We study the influence of the ion MAGNETic-drift direction relative to the active X-point (favourable and unfavourable configurations) on edge turbulence, transport, and the radial electric field $E_r$ in ASDEX Upgrade and TCV. First-principles gyrokinetic simulations of the edge and scrape-off layer are performed in diverted X-point geometry using the spectral full-$f$ GENE-X code. Two matched pairs of L-mode discharges are simulated and validated against the available measurements in all four cases, showing good agreement, in particular for the $E_r$ profiles. A radial force-balance analysis shows that the deeper $E_r$ well in the favourable configuration is determined by the larger poloidal ion flow near the separatrix, which cannot be reproduced by neoclassical solvers and is identified in axisymmetric simulations as turbulence-driven. We then derive an exact evolution equation for the mean poloidal-flow acceleration from the full-$f$ gyrokinetic vorticity equation, which identifies the radial gradient of the total velocity stress as its nonlinear drive. The observed asymmetry is found to arise from stronger nonlinear energy transfer into the mean flow in the favourable configuration, associated with enhanced nonlinear $E\times B$ advection of vorticity near the separatrix and X-point. Flux-driven TCV simulations further show that the asymmetry persists at matched power more than six times the L-mode value. Assuming a critical $E_r$ at the L-H transition, this yields an estimated ratio of approximately 1.7 between the unfavourable and favourable L-H power thresholds, close to the experimental factor of two. Overall, the unfavourable configuration exhibits larger fluctuation amplitudes, a weaker $E_r$ well, stronger geodesic acoustic modes, and shorter energy confinement times for the same profiles, which may explain the observed difference in access to high-confinement regimes.
[abstract 40 / 43] (score: 2) - Title: Eliminating Tokamak Disruptions with FeedbackAuthors: H. R. Strauss,Comments: 17 pages, 11 figuresSubjects: physics.plasm-phCreated: 2026-10-05; Updated: 2026-10-06; Datestamp: 2026-10-06
Tokamak disruptions caused by tearing modes can be prevented with MAGNETic feedback. A database of DIII-D locked mode disruptions provides criteria for major disruptions. The main criterion is that the q = 2 rational surface must be sufficiently close to the resistive wall surrounding the plasma to interact with it. This is shown in simulations of a sequence of model equilibria derived from the database. If the wall is ideally conducting, major disruptions do not occur. Magnetic feedback emulates a conducting wall, and can prevent major disruptions. Feedback coils must be designed appropriately, otherwise they are not effective in disruption prevention. Simulations of a model of MST also show the q = 2 criterion for major disruptions, as well as feedback stabilization. Feedback offers an attractive alternative to disruption mitigation by impurity injection.
[abstract 41 / 43] (score: 2) - Title: Magnetohydrodynamic coronal modelling with high-fidelity MAGNETogramsAuthors: Haopeng Wang, Stefaan Poedts, Wensi Wang, Rayan Dhib, Andrea Lani, Martina Condoluci, Tinatin Baratashvili, Quentin Noraz, Luis Linan, Hyun-Jin Jeong, Junyan Liu, Zhenguang Huang, Rui Liu, Lingyu Dong, Rui Zhuo, Liping Yang, Giovanni Alejandro Pinzón Estrada, Jasmina M. Magdalenić Zhukov, Brigitte Schmieder,Comments: 12 pages, 7 figuresSubjects: astro-ph.SRCreated: 2026-10-05; Updated: 2026-10-06; Datestamp: 2026-10-06
To resolve coronal structures in detail, it is essential to constrain the coronal model using high-fidelity MAGNETograms with minimal smoothing. In this paper, we improve the numerical stability of COCONUT to enable efficient coronal MHD simulations driven directly by photospheric MAGNETograms, including MAGNETic field strengths exceeding 1000 Gauss (G), and then use it to investigate the impact of small-scale MAGNETic field structures that are typically filtered out of photospheric MAGNETograms on the coronal simulation results. We constrain this model with two types of MAGNETograms: the high-fidelity HMI photospheric MAGNETogram with only minor preprocessing through Gaussian smoothing, which preserves MAGNETic field strengths reaching 1500 G, and one processed using 50th-order filtered spherical harmonics, where the MAGNETic field strength is limited to below 100 G. The results demonstrate that the COCONUT can reproduce the large-scale coronal structures revealed by pB and EUV observations. Compared with the coronal MHD simulation constrained by a conventionally filtered MAGNETogram, the simulation constrained by the high-fidelity MAGNETogram yields approximately $50\%$ more OMF and produces EUV images that are more consistent with the observations. Moreover, the results show that when viewed from low latitudes in certain EUV passbands, such as the 193~Å channel, open-field regions near the solar poles may appear as bright structures that are typically associated with closed-field regions. This finding highlights the need for solar polar-orbiting missions to overcome the limitations and ambiguities arising from the restricted view of the polar regions from the ecliptic plane and to provide more complete full-Sun observations.
[abstract 42 / 43] (score: 2) - Title: Continuous Gravitational Waves from Thermo-Elastic Mountains in Ultraluminous X-ray PulsarsAuthors: Hong-Bo Li, Ziming Wang, Lijing Shao, Ren-Xin Xu,Comments: 7 pages, 3 figures, and Supplemental MaterialSubjects: astro-ph.HECreated: 2026-10-05; Updated: 2026-10-06; Datestamp: 2026-10-06
Fast-spinning, nonaxisymmetrically deformed neutron stars (NSs) are promising targets for continuous gravitational-wave (CGW) searches with current and next-generation ground-based detectors. Ultraluminous X-ray pulsars (ULXPs), characterized by super-Eddington accretion and strong MAGNETic fields, provide extreme environments in which substantial nonaxisymmetric deformations may develop. In this Letter, we investigate thermo-elastic mountains generated by MAGNETically induced temperature asymmetries in the accreted crusts of ULXPs. We connect the crustal thermal structure to an accretion-column model and solve the full anisotropic heat-transport equation, extending previous perturbative treatments into the nonlinear, strongly MAGNETized regime. We find that the weak-field approximation begins to break down near $B_{\rm ref}\sim10^{13}\,{\rm G}$, beyond which nonlinear anisotropic heat transport significantly modifies the quadrupolar thermal response. The resulting thermal asymmetries generate substantial thermo-elastic mass quadrupoles at higher field strengths. Although the currently known ULXPs are unfavorable CGW targets because of their relatively slow spins and, in most cases, large distances, our illustrative spin-evolution calculations show that a NS can enter the super-Eddington accretor phase with a spin period of order $20\,{\rm ms}$. Such rapidly rotating Galactic ULXPs could lie within the projected sensitivities of next-generation detectors such as the Einstein Telescope and Cosmic Explorer. These results extend thermal-mountain physics into the strongly MAGNETized regime relevant to ULXPs and connect super-Eddington accretion with prospective CGW observations.
[abstract 43 / 43] (score: 2) - Title: Dyonic Simpson Visser black-bounce spacetime surrounded by an exotic Einstein cluster in general relativityAuthors: Pedro Cañate, Joseph Sultana, Demosthenes Kazanas,Comments: 16 pages, 2 figuresSubjects: gr-qcCreated: 2026-10-05; Updated: 2026-10-06; Datestamp: 2026-10-06
In this work, we present the Simpson-Visser black-bounce (SV-BB) spacetime with both electric and MAGNETic charges (the dyonic SV-BB) as an exact solution of general relativity coupled to Maxwell electrodynamics and an anisotropic fluid with vanishing radial pressure. We assume the anisotropic fluid represents an Einstein cluster, which consists of a dense system of particles moving in circular orbits that generate only tangential pressure and zero radial pressure. We show that the dyonic SV-BB metric, which provides a regular BLACK HOLE spacetime, can be obtained as an exact solution to the Einstein field equations sourced by a combination of an Einstein cluster (which is responsible for providing the exotic matter required to keep a black-bounce throat open) and an electroMAGNETic field in the framework of Maxwell electrodynamics.
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