Current date: 2026-05-22
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Datestamp limit: 2026-05-22 (0 days ago)
Created/updated limit: 2026-05-15 (7 days ago)
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Suggested sets: physics, physics:astro-ph, physics:gr-qc, physics:physics
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Scoring abstracts
Number of records retrieved: 701
Keyword score statistics
score 10 -- 1 abstracts
score 6 -- 2 abstracts
score 5 -- 5 abstracts
score 4 -- 5 abstracts
score 3 -- 9 abstracts
score 2 -- 24 abstracts
in total -- 46 abstracts
Articles that appeared on 2026-05-22
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[abstract 1 / 46] Wow! (score: 10)
- Title: Quasi-Simultaneous Broadband Spectral Energy Distributions of a Sample of FERMI Blazars -- I. Correlation ResultsAuthors: Yi Zhong, Zhujian Wan, Rui Xue, Hubing Xiao, Dingrong Xiong, Ze-Rui Wang,Comments: 15 pages, 7 figures, 6 tables, accepted for publication by MNRASSubjects: astro-ph.HECreated: 2026-05-21; Updated: 2026-05-22; Datestamp: 2026-05-22
Blazars' non-thermal emission shows rapid variability across all wavelengths, so spectral energy distributions (SEDs) built from quasi-simultaneous data are crucial for revealing the JETs physical properties. In this work, we construct quasi-simultaneous broadband SEDs for 93 FERMI BLAZARs (56 FSRQs, 35 BL Lacs, and 2 BLAZAR candidates of uncertain type), fit both peaks with cubic functions to allow for potential asymmetries, and examine correlations among key parameters. Our main results are summarized as follows: (1) We find that SYNCHROTRON peak frequency and curvature are only weakly related, suggesting that charged particles are accelerated by mixed acceleration mechanism. (2) The BLAZAR sequence is confirmed in the observer's frame through negative correlations of both the bolometic luminosity $\log L_{\rm bol}$ and the Compton dominance $\log Y$ with the SYNCHROTRON peak frequency $\log ν_{\rm syn}^{\rm peak}$. After correcting for Doppler boosting, a weak positive correlation emerges between $\log L_{\rm bol}$ and $\log ν_{\rm syn}^{\rm peak}$. FSRQs and BL Lacs exhibit distinct correlation patterns within the BLAZAR sequence, indicating differences in cooling mechanisms. (3) Using variability time lags between 0.1-1 GeV and 1-300 GeV light curves, we estimate lower limits of Doppler factors for 4 sources, providing a JET-speed diagnostic anchored directly to the $γ$-ray emission zone.
[abstract 2 / 46] Yes (score: 6) - Title: The powerful shocks in RS Oph: NUSTAR X-ray data and a complete reviewAuthors: Marina Orio, Gerardo Juan M. Luna, Ehud Behar, Rebecca Diesing, Jay Gallagher, Joanna Mikolajewska, Jan-Uwe Ness,Comments: Accepted for publication in the Astrophysical JournalSubjects: astro-ph.HECreated: 2026-05-21; Updated: 2026-05-22; Datestamp: 2026-05-22
In the 2021 outburst of RS Ophiuchi, the gamma- and the X-ray flux were measured quasi-simultaneously from day 1 after the optical peak, offering the first comprehensive view of shocks in a nova occurring in a symbiotic system. We present a previously unpublished observation done with NUSTAR in the 3-79 keV range, 9 days after maximum, and we review the complex history of the evidence of shocks in the previous outbursts of this nova in the light of the intensive X-ray monitoring of 2021. We find evidence that the shock causing the particle acceleration measured with the Cherenkov telescopes produced also the thermal flux detected in the 0.2-30 keV X-ray range, while the large gamma-ray flux observed with FERMI after about a day, is not consistent with the X-ray observations. We conclude that an initial, strong shock, with particle-particle loss timescale shorter than the timescale of particle acceleration at energy higher than a few GeV, occurred close to the red giant atmosphere,where either the X-rays' emitting volume was reduced by turbulence, or - perhaps less likely - the X-rays were completely absorbed by large column density near the giant and by the accretion wake along the line of sight. We compare RS Oph with other novae in long period systems with evolved companions,discussing how the shocks' phenomenology is a powerful tool to derive other physical parameters. Finally, we discuss predictions that in T CrB, expected to have a new outburst within the next few years, the shocks may not be as energetic as in RS Oph.
[abstract 3 / 46] Yes (score: 6) - Title: Discovery of a Featureless Tidal Disruption Event at z~1 with the Wide Field Survey TelescopeAuthors: Jiazheng Zhu, Zelin Xu, Ning Jiang, Ji-an Jiang, Tinggui Wang, Yuhan Yao, Ryan Chornock, Erica Hammerstein, Yibo Wang, Min-Xuan Cai, Shifeng Huang, Wenkai Li, Mingxin Wu, Chichuan Jin, Jie Lin, Jianwei Lyu, Dezheng Meng, Weiyu Wu, Zhengyan Liu, Junhan Zhao, Ziqing Jia, Chengyi Wang, Lulu Fan, Xu Kong, Feng Li, Ming Liang, Jinling Tang, Hairen Wang, Jian Wang, Yongquan Xue, Ji Yang, Hongfei Zhang, Wen Zhao, Qingfeng Zhu,Comments: 12 pages, 6 figures, Accepted for ApJLSubjects: astro-ph.HECreated: 2026-05-21; Updated: 2026-05-22; Datestamp: 2026-05-22
We report the discovery of tidal disruption event (TDE) WFST250820mmsw/AT2025wet by the 2.5-meter Wide Field Survey Telescope (WFST). It exhibits a blue nuclear flare throughout the observed evolution with a g-band peak magnitude ~22, which is about 3 magnitudes brighter than its host galaxy. A Keck/LRIS spectrum taken near the optical peak reveals a featureless blue continuum, with no discernible emission lines. However, its redshift can be accurately determined to be 1.037 by its host galaxy absorption lines. Blackbody fits to the multiband spectral energy distribution (SED) of AT2025wet yield a constant temperature of ~19,000K and a peak luminosity of (8.27 +0.92 -0.71)*10^44 erg s^-1 while actually the SED likely peaks at a much shorter wavelength than a 19,000K blackbody. The SED modeling of the host galaxy implies a stellar mass of ~10^11.2 M_odot and an estimated central BLACK HOLE mass of ~10^8 M_odot, with no evidence of significant ACTIVE GALACTIC NUCLEus activity prior to the flare. All of these observations are well consistent with a featureless TDE scenario, making it the highest-redshift non-JETted TDE known to date. TDEs at such high redshift provide us a unique opportunity to explore the intrinsic SEDs of TDEs, particularly to test whether they peak in the extreme-UV regime, thereby addressing the missing energy puzzle and the origin of optical emission in TDEs. Ongoing surveys represented by WFST and the Legacy Survey of Space and Time (LSST) are expected to discover an increasing number of TDEs at higher redshifts, which will extend our census of SMBHs across redshift space and help unravel the mysteries of optical TDEs through direct probes of their UV emission.
[abstract 4 / 46] Yes (score: 5) - Title: A Magnetized Black Hole Envelope Model for Little Red DotsAuthors: Shinsuke Takasao, Kohei Inayoshi,Comments: 21 pages, 13 figures, submitted to ApJSubjects: astro-ph.GA astro-ph.HE astro-ph.SRCreated: 2026-05-20; Updated: 2026-05-22; Datestamp: 2026-05-22
Recent observations have revealed a unique class of ACTIVE GALACTIC NUCLEi (AGNs), termed little red dots (LRDs). These objects are hypothesized to be powered by massive BLACK HOLEs rapidly accreting in dense gaseous environments. Theoretical studies suggest that the circum-nuclear gas can form an optically thick BLACK HOLE envelope (BHE), whose structure resembles the atmospheres of convective stars near the Hayashi limit. Given that such cool stars typically generate MAGNETic fields, we propose a dynamical and spectral model for an LRD enshrouded by a MAGNETized BHE. Assuming spherical free-fall accretion onto a rotating, MAGNETized BHE, our model accounts for key observational properties of LRDs. We propose that the Doppler component of broad emission lines originates from plasma clumps co-rotating within the BHE MAGNETosphere. Including additional broadening due to electron scattering allows the resulting line profile to be fitted by a combination of a Gaussian core and an exponential tail. This model can reproduce Doppler components up to a few thousand ${\rm km~s^{-1}}$. We suggest that conventional BLACK HOLE mass estimation methods based on the virial relation may yield erroneous results. Furthermore, our model is consistent with X-ray non-detections in LRDs. We evaluate the X-ray luminosities of two potential sources: the post-shock region of accretion shocks and a MAGNETically heated corona. We find that these X-ray luminosities are constrained to $\lesssim 10^{41}~{\rm erg~s^{-1}}$ across a wide range of BLACK HOLE masses ($10^5 M_\odot \lesssim M_{\rm BH}\lesssim 10^7M_\odot$) and accretion rates, consistent with current upper limits on X-ray emission.
[abstract 5 / 46] Yes (score: 5) - Title: A Weak Fe K$β$ Emission Line in the Broad-Line Radio Galaxy 3C 111 Observed with XRISM: An Ionized Wind Absorption Feature?Authors: Kouichi Hagino, Motoki Kino, Lukasz Stawarz, Kenzo Kawamura, Kazuhiro Hada, Hirofumi Noda,Comments: 10 pages, 6 figures, 2 tables, accepted for publication in ApJSubjects: astro-ph.HE astro-ph.GACreated: 2026-05-21; Updated: 2026-05-22; Datestamp: 2026-05-22
We present the results of an observation of the broad-line RADIO GALAXy 3C 111 with the X-Ray Imaging and Spectroscopy Mission (XRISM). The unprecedentedly high spectral resolution of XRISM/Resolve revealed that the Fe K$β$ emission line is significantly weaker than expected from the Fe K$α$ line. This feature may be explained by a blueshifted absorption line from an ionized wind overlapping the Fe K$β$ energy. The inferred outflow velocity is 4600 km s$^{-1}$ or 17200 km s$^{-1}$, depending on whether the absorption feature is identified as Fe XXVI or Fe XXV, with the current data unable to distinguish between the two interpretations. Based on spectral modeling, the kinetic power of the wind is estimated to lie in the range 10$^{41}$-10$^{44}$ erg s$^{-1}$, although this estimate is subject to large uncertainties primarily due to the poorly constrained location of the absorber. The inferred wind power is smaller than the JET power of 3C 111 ($\sim 3\times 10^{44}$ erg s$^{-1}$), and is broadly consistent with theoretical expectations that the JET power exceeds that of disk winds.
[abstract 6 / 46] Yes (score: 5) - Title: MICONIC: The multiphase circumnuclear region of Centaurus A as seen with JWST/MIRI MRS observations. I. Spectral inventory and properties of the warm molecular diskAuthors: L. Evangelista, P. Guillard, J. Martin, P. Salomé, A. Alonso Herrero, L. Pantoni, L. Hermosa Muñoz, V. Buiten, A. Labiano, M. García-Marín, L. Colina, T. Böker, D. Dicken, M. J. Ward, G. Wright, P. van der Werf, S. Garcia-Burillo, M. Baes, A. Eckart, G. Östlin, D. Rouan, F. Walter, R. A. Riffel, M. Güdel,Comments:Subjects: astro-ph.GACreated: 2026-05-21; Updated: 2026-05-22; Datestamp: 2026-05-22
Supermassive BLACK HOLEs power Active Galactic Nuclei (AGN), injecting energy that regulates accretion and shapes host galaxies. We investigate the morphology, excitation, and kinematics of molecular hydrogen (H2) in the inner circumnuclear disk of Centaurus A, the nearest RADIO GALAXy. We present JWST/MIRI MRS integral-field spectroscopy of the central 170x100 pc2 at 0.3"-0.7" (5-12 pc) resolution, focusing on pure rotational H2 lines. The spectra show strong nuclear continuum and bright H2 emission from S(1) to S(8), including the first S(8) detection in Centaurus A. Optically thin nuclear lines enable maps of temperature, column density, and ortho-to-para ratio from spaxel-level excitation-diagram fitting. Warm H2 shows a complex morphology, dominating the central region where CO emission is weak or undetected. Low-excitation H2 lines trace an inhomogeneous ring with a 20-pc-radius cavity aligned with the JET's near side, suggesting that the JET affects the morphology of the molecular disk. Higher-excitation lines form filamentary structures around the AGN. Kinematics are rotational with an S-shaped distortion, indicating non-circular motions or a warped disk. A coherent, low-dispersion (70 km/s) streamer spirals inward. A power-law temperature distribution yields a warm (100-2000 K) H2 mass of (5.6+/-1.4)e5 Msun and a dynamical mass of 5e8 Msun within 100 pc. Shock excitation is supported by enhanced H2/continuum and H2/PAH ratios, elevated [Ne III]/[Ne II], and sub-equilibrium ortho-to-para ratios (1.6-2.4). Turbulent dissipation can balance H2 cooling and likely dominates heating beyond 30 pc. In the inner 100 pc of Centaurus A, AGN feeding and feedback are linked: shocks excite H2, regulate the gas temperature, and prevent cooling below 100 K, explaining the weak CO emission and lack of a massive outflow. These shocks may drive angular momentum loss and help fuel the nucleus.
[abstract 7 / 46] Yes (score: 5) - Title: Search for radio POLARIZATION in the particle-accelerating colliding-wind binaries WR 147 and HD 167971Authors: A. B. Blanco, M. De Becker, P. Benaglia, S. del Palacio,Comments: Accepted for publication in Astronomy & AstrophysicsSubjects: astro-ph.SR astro-ph.HECreated: 2026-05-21; Updated: 2026-05-22; Datestamp: 2026-05-22
Particle-accelerating colliding-wind binaries (PACWBs) are multiple systems of massive stars in which strong stellar winds collide, accelerating particles to RELATIVISTIC energies. This population of RELATIVISTIC particles emits NT radiation, including SYNCHROTRON radiation in the radio domain. This emission is expected to be linearly polarized, but the POLARIZATION signature has not yet been detected for a PACWB. Our objective is to quantify the linear POLARIZATION of SYNCHROTRON radiation in two well-known PACWBs and to interpret our measurements within the framework of the physics of these specific NT emitters. We observed the PACWBs WR 147 and HD 167971 with the Very Large Array (VLA) radio interferometer in the frequency bands L and C (1-2 and 4-8 GHz, respectively), where SYNCHROTRON emission is expected to be more prominent. We performed POLARIZATION calibration and analyzed the resulting Stokes maps. We did not detect any POLARIZATION signature for either of the two targets in either of the two bands, even when considering narrower bands to mitigate the effect of bandpass dePOLARIZATION. The most conservative upper limit on the POLARIZATION degree is on the order of 1% for both targets. The lack of linear POLARIZATION for the two targets is likely attributable to a combination of effects, including the turbulent nature of the MAGNETic field in the SYNCHROTRON-emitting region, and dePOLARIZATION processes based on Faraday rotation that are certainly active in these sources. Their complex geometry, unresolved by the VLA at these frequencies, is most likely to lead to beam dePOLARIZATION. We emphasize that, in contrast to other canonical SYNCHROTRON sources, PACWBs are also subject to thermal dilution. This is especially relevant for systems with stars whose winds are strong enough to contribute copiously to thermal emission, such as those harboring a Wolf-Rayet component.
[abstract 8 / 46] Yes (score: 5) - Title: Polarized 3D Synthetic Turbulence I: Magnetic Field Line Random WalkAuthors: Matthieu Bouchet, Yoann Génolini, Silvio S. Cerri, Alexandre Marcowith, Philipp Mertsch,Comments: 20 pages, 14 figuresSubjects: astro-ph.HE astro-ph.SR physics.plasm-phCreated: 2026-05-21; Updated: 2026-05-22; Datestamp: 2026-05-22
The behavior of MAGNETic field lines in a turbulent plasma is a key property of the medium, with important consequences for plasma dynamics and charged-particle transport. We study the diffusion properties of MAGNETic field lines in synthetic turbulence featuring different POLARIZATION configurations for the MAGNETic perturbations, as prescribed by the existing MAGNETohydrodynamic modes (namely, Alfvénic and MAGNETosonic). These turbulent field realizations are then compared with the isotropic (or, random) POLARIZATION case, which is the one typically adopted in the literature. We construct polarized synthetic turbulence simulations and study the properties of field lines through the running diffusion coefficient. Our key findings can be summarized as follow: (i) field line wandering is strongly dependent on POLARIZATION configurations, (ii) we unveil that the sub-diffusive phase of field line is highly dependent on the POLARIZATION and is well reproduced by theoretical predictions based on Corrsin's hypothesis in the low turbulence level regime, (iii) in particular the scaling of the asymptotic diffusion coefficient in MAGNETosonic-like POLARIZATION is $(δB/B)^4$ at odd with the $(δB/B)^2$ scaling found in the quasi-linear regime for random POLARIZATION, (iv) interestingly we note that the subdiffusive phase of field line transport in the MAGNETosonic-like POLARIZATION follows closely the one observed in recent high resolution MHD turbulence simulations, we end giving a word of caution when FL transport is investigated in such simulations.
[abstract 9 / 46] Yes (score: 4) - Title: Satellite-borne $γ$-ray astrophysics from coherent interactions in oriented crystalsAuthors: Pietro Monti-Guarnieri, Gianfranco Paternò, Alexei Sytov, Elisabetta Cavazzuti, Luigi Costamante, Sara Cutini, Matteo Duranti, Pierluigi Fedeli, Richard J. Gaitskell, Vincenzo Guidi, Viktar Haurylavets, Savvas M. Koushiappas, Francesco Longo, Sofia Mangiacavalli, Andrea Mazzolari, Michela Prest, Marco Romagnoni, Alessia Selmi, Mattia Soldani, Victor Tikhomirov, Valerio Vagelli, Erik Vallazza, Laura Bandiera,Comments:Subjects: astro-ph.HECreated: 2026-05-21; Updated: 2026-05-22; Datestamp: 2026-05-22
High-density and high-Z crystals are key elements of most space-borne $γ$-ray telescopes operating at gigaelectronvolt energies (such as FERMI-LAT). The lattice structure is usually neglected in the development of a crystalline detector, although its effects on the energy deposit development should be taken into account, since the interactions of a high-energy ($\sim$ 10~GeV) photon or e$^\pm$ impinging along the axis of an oriented crystal are different than those observed in a fully isotropic medium. Specifically, if the angle between a photon (e$^\pm$) trajectory, and the crystal axis is smaller than $\sim$ 0.1$^\circ$, a large enhancement of the pair production (bremsstrahlung) cross section is observed. Consequently, a photon-induced shower inside an oriented crystal develops within a much more compact region than in an amorphous medium. Moreover, for photon energies above a few gigaelectronvolt and incidence angles up to several degrees, the pair production cross section exhibits a pronounced dependence on the angle between the crystal axis and the photon POLARIZATION vector. In this work we show that these effects could be exploited to develop a novel class of light-weight pointing space-borne $γ$-ray telescopes, capable of achieving an improved sensitivity and resolution, thanks to a better shower containment in a smaller volume, with respect to non-oriented crystalline detectors. We also show that an oriented tracker-converter system could be used to measure the POLARIZATION of a $γ$-ray source above few gigaelectronvolts, in a regime that remains unexplorable through any other detection technique. This novel detector concept could open new pathways in the study of the physics of extreme astrophysical environments and potentially improve the detector sensitivity for indirect DARK MATTER searches in space
[abstract 10 / 46] Yes (score: 4) - Title: Spectral Evidence of Heavy Nuclei from the Neutron Star Crust in Magnetar BurstsAuthors: Sheng-Lun Xie, Yun-Wei Yu, Shao-Lin Xiong, Wang-Chen Xue,Comments:Subjects: astro-ph.HECreated: 2026-05-21; Updated: 2026-05-22; Datestamp: 2026-05-22
The crust of a neutron star (NS) provides a unique laboratory for studying matter under extreme density and MAGNETic field conditions that cannot be realized in terrestrial experiments. However, direct observational constraints on its composition have remained very limited. Magnetar bursts provide a promising means to probe the nuclear composition of the outer crust, as their energy release may be associated with stress-driven yielding of the crustal Coulomb lattice (including plastic deformation) and MAGNETic RECONNECTion in the surrounding MAGNETosphere. We develop a general-purpose radiative transfer framework for a strongly MAGNETized electron--ion thermal plasma (MEITP) and apply it to the observed X-ray burst spectra. The spectral fits disfavor light-ion compositions and instead favor plasmas characterized by effective charge numbers around $Z \sim 37$. These results provide spectral evidence for the participation of heavy nuclei in MAGNETar bursts, offer new observational constraints on the baryonic content and the location of the emitting fireballs, and further imply a crustal origin of the heavy ions.
[abstract 11 / 46] Yes (score: 4) - Title: Vacuum breakdown in a misaligned MAGNETized Kerr spacetimeAuthors: Ruixin Yang, Songbai Chen, Jiliang Jing,Comments: 15 pages,8 figuresSubjects: gr-qcCreated: 2026-05-21; Updated: 2026-05-22; Datestamp: 2026-05-22
Electron-positron ($e^{+}e^{-}$) pair creation by vacuum breakdown around compact objects is believed to power high-energy astrophysical transients like GAMMA-RAY BURSTs (GRBs). In this work, we focus on vacuum breakdown around a Kerr BLACK HOLE (BH) immersed in an asymptotically uniform MAGNETic field that is inclined with respect to the BH spin axis. The dyadoregion, the region where the induced electric field exceeds the critical value $E_{\text{c}}=m_{e}^{2}c^{3}/(e\hbar)$, is identified via the electroMAGNETic invariants. It is found that the dyadoregion consists of several lobes whose number, size, and orientation vary with the inclination. We also estimate the electroMAGNETic energy available for pair creation and derive a beaming factor that allows a conversion between the intrinsic dyadoregion energy and the observed isotropic energy. The thermodynamic properties of the resulting electron-positron-photon ($e^{+}e^{-}γ$) plasma are included, revealing an initial MAGNETic dominance. The evaluation of the minimum MAGNETic field required shows that misaligned MAGNETic fields generally favor pair creation more than aligned ones.
[abstract 12 / 46] Yes (score: 4) - Title: PIC simulations of nonRELATIVISTIC high-Mach-number oblique shocks propagating in a turbulent mediumAuthors: Karol Fulat, Eloise Moore, Mahmoud Alawashra, Michelle Tsirou, Artem Bohdan, Takanobu Amano, Martin Pohl,Comments: 16 pages, 10 figures, accepted for publication in ApJSubjects: physics.plasm-ph astro-ph.HE physics.space-phCreated: 2026-05-21; Updated: 2026-05-22; Datestamp: 2026-05-22
Collisionless shocks are common in astrophysical systems and stand as sites of particle acceleration. While particles at perpendicular shocks may not return to the upstream region, at oblique shocks a fraction of energetic electrons manage to escape the shock and travel upstream. An extended region known as the electron foreshock is formed, where these reflected particles drive various instabilities that may promote electron acceleration. Here we present the first 2D3V particle-in-cell (PIC) simulations of electron-ion non-RELATIVISTIC oblique shocks that explore the interaction of the foreshock with pre-existing compressive turbulence with relative amplitude of 15% based on interstellar medium estimates. We find that pre-existing turbulence influences the emergence and behavior of the whistler-wave instability, as it enhances the amplitudes of the MAGNETic-field fluctuations and leads to larger nonlinear structures. This impacts the dynamics of the reflected electrons, resulting in a shorter and hotter electron foreshock. At the end of our simulations, with pre-existing upstream turbulence we observe non-thermal electrons that are more numerous, reach higher energies, and carry a larger portion of the total energy.
[abstract 13 / 46] Yes (score: 4) - Title: Magnetar Fireballs and Short Bursts: Curved Spacetime Lensing, QED Effects, High-Energy Spectra and Polarization, and Energy-Time Impulse ResponsesAuthors: Zorawar Wadiasingh, Hoa Dinh Thi, Constantinos Kalapotharakos, Kun Hu, Matthew G. Baring, Alice K. Harding, George Younes, Sebastien Guillot, Andrea Sanna, Michela Negro, Jeremy D. Schnittman, Oliver J. Roberts, Eric Burns, Chin-Ping Hu, Ersin Göğüş,Comments: Comments welcome!Subjects: astro-ph.HE astro-ph.SRCreated: 2026-05-21; Updated: 2026-05-22; Datestamp: 2026-05-22
Magnetar short bursts (SBs) are hard X-ray transients of durations $0.01-1$ s peaking at $\sim 10-100$ keV, and are prime targets for new high-energy missions and polarimeters. The recent association of SBs with bright radio bursts in SGR 1935+2154 has broadened interest in SB physics. We present new advanced fireball models combining general RELATIVISTIC light bending, polarized transport in MAGNETized photospheres, MAGNETic photon splitting attenuation, and MAGNETospheric vacuum birefringence. These models also have relevance to trapped fireballs in MAGNETar giant flare pulsating tails. We adopt confined flux tube geometries consistent with adiabatic fireballs, and anisotropic/polarized emergent intensities to produce spectra and POLARIZATIONs, and energy-time Stokes impulse responses. We predict that most fireballs are highly linearly polarized, especially when vacuum birefringence is important. There is rich potential for diagnostics: coexisting direct and lensed delayed images, gaps by occultation of the neutron star surface, and Shapiro+Rømer delay with temporal caustics. These effects can imprint spin phase dependence of the spectral and POLARIZATION character of bursts. Predicted signatures depend strongly on viewing geometry, fireball configuration, and photon splitting assumptions, yielding large variance in model high-energy spectral shapes and cutoffs, and energy-dependent POLARIZATION. The models can reproduce established double-blackbody SB spectral phenomenology, and we find that the unusual April 2020 radio-associated SB from SGR 1935+2154 is broadly consistent with a footpoint close to the MAGNETic pole, and possibly near pole-on viewing geometry. Our models motivate reverberation-style analyses for SBs and suggest that high-quality data might constrain source geometry, burst crustal footpoints, and, potentially, neutron star masses and radii.
[abstract 14 / 46] (score: 3) - Title: Single-source-class interpretation of the diffuse astrophysical neutrino fluxAuthors: Walter Winter, Damiano F. G. Fiorillo, Sara Buson,Comments: Version accepted for publication in PRD including several clarifications. 19 pages, 9 figures, 1 table. Data can be retrieved at https://zenodo.org/records/19820788Subjects: astro-ph.HE hep-phCreated: 2026-05-21; Updated: 2026-05-22; Datestamp: 2026-05-22
We explore the interpretation that the diffuse astrophysical neutrino flux is dominated by a single standard candle-like source class. Since recent observations favor a broken power law with a spectral break around 30 TeV, we postulate that the $pγ$ channel is the dominant neutrino production process creating a peak at these energies. We use a SOPHIA-based photo-pion interaction model with a thermal target including high-energy processes, such as multi-pion production, which turns out to be relevant for the interpretation. We demonstrate that target photon temperatures 0.1 to 1 keV are preferred in a multi-parameter fit, whereas the maximal neutrino energies can be limited by A) soft injection spectra, B) a maximal proton energy in the PeV range, or C) MAGNETic field effects on the secondary muons, pions, and kaons with B in the few 10 kG range. We predict that future measurements, such as of the neutrino flavor composition or neutrino-antineutrino ratio (Glashow resonance), can discriminate scenarios. We also point out that the parameters obtained in our generic approach, such as in the strong MAGNETic field values, might be indicative for an AGN core origin as a driver of the diffuse flux.
[abstract 15 / 46] (score: 3) - Title: Evolution of Quasi-Periodic Eruptions in the post-TDE Accretion Disk Perturbed by an Orbiting StarAuthors: Martin Mondek, Michal Zajaček, Henry Best, Taj Jankovič, Vladimír Karas, Petr Kurfürst,Comments: Accepted for publication in A&A journal; 13 pages, 7+4 figures, 4 tablesSubjects: astro-ph.HE astro-ph.GACreated: 2026-05-21; Updated: 2026-05-22; Datestamp: 2026-05-22
Quasi-periodic eruptions (QPEs) are a recently discovered class of highly variable X-ray bursts originating in galactic nuclei. These high-amplitude bursts exhibit periodicity ranging from tens of minutes to several days. QPEs are also characterized by variable peak amplitudes that can vary by a factor of few. While multiple physical models have been proposed to explain QPE light curves, none can fully account for all the observed features. A possible connection between QPEs and tidal disruption events (TDEs) has been suggested, particularly due to the past optical/UV outbursts that can be traced back for several sources, the long-term decay in the continuum luminosity, and the soft, thermal-dominated X-ray spectrum. Our primary goal is to verify whether the long-term decrease in eruption amplitudes detected for some QPE sources is consistent with the accretion disk being formed following a TDE. In this work, we adopt a simplified extreme mass ratio inspiral (EMRI) scenario, where a Solar-type star orbits a supermassive BLACK HOLE (SMBH) and collides with an accretion disk twice per orbit, generating eruptions. We assume a post-TDE disk that follows a temporal power-law decline in mass accretion ($\propto t^{-p}$, $p>0$). As our aim is to develop a toy-model scenario, we have used purely analytical methods without considering all intervening processes in their full generality. Indications are that (i) the observed long-term decline in QPE amplitudes can be reproduced if the first monitored epoch occurs years to a few decades after the tidal disruption, (ii) stellar mass loss caused by ablation can play an important role in the evolution of QPE amplitudes in systems with heavy main-sequence (MS) stars.
[abstract 16 / 46] (score: 3) - Title: Investigating central STAR FORMATION in local AGN host galaxies: is there tension between coeval growth and AGN feedback?Authors: Q. Ni, K. Nandra, A. Merloni, J. Comparat, D. Tubín-Arenas, Y. Zhang,Comments: 15 pages, 17 figures. Accepted for publication in A&ASubjects: astro-ph.GA astro-ph.HECreated: 2026-05-20; Updated: 2026-05-22; Datestamp: 2026-05-22
It has been argued that supermassive BLACK HOLEs (BHs) coevolve with the central parts of galaxies, as a result of the common fuel for both the BH and STAR FORMATION in the galaxy central region, as supported by the particularly significant relation between BH growth and the central mass density within 1 kpc found among star-forming galaxies. In the context of this scenario, one would naturally expect a close observational link between AGN activity and STAR FORMATION activity in the central regions, e.g., the surface STAR FORMATION rate density in the central 1 kpc region ($Σ_{\rm SFR, 1~kpc}$), as the manifestation of coeval growth. With ~3000 galaxies in the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey that have X-ray coverage from SRG/eROSITA, XMM-Newton, or Chandra, we studied how the X-ray AGN fraction varies with $Σ_{\rm SFR, 1~kpc}$. We found that the fraction of X-ray AGNs with relatively higher specific BH accretion rates increases with $Σ_{\rm SFR, 1~kpc}$, consistent with the expectation. Comparison of the mean STAR FORMATION rate surface density ($Σ_{\rm SFR}$) profiles of the host galaxies of these AGNs and normal galaxies sharing similar properties reveals elevated $Σ_{\rm SFR}$ in AGN hosts across the entire central region. As for optically-selected AGNs, their hosts also tend to show high $Σ_{\rm SFR}$ in the central regions on average compared to normal galaxies, but are discrepant with X-ray AGNs in terms of the trend of AGN fraction vs. $Σ_{\rm SFR, 1~kpc}$, which can be explained by selection effects. While these general trends all support the coeval growth scenario, they do not contradict observational evidence for AGN feedback, as the time-averaged effects from local AGN feedback are modest in star-forming regions.
[abstract 17 / 46] (score: 3) - Title: Gravitational wave detectability range informed by external messengersAuthors: S. Ronchini, A. Chopra, T. Dal Canton, B. Banerjee, A. L. De Santis, M. Branchesi,Comments:Subjects: astro-ph.HE gr-qcCreated: 2026-05-20; Updated: 2026-05-22; Datestamp: 2026-05-22
A rapid estimate of gravitational-wave (GW) detectability associated with astronomical transients is crucial for optimizing multi-messenger follow-up strategies and for constraining the physical origin of the transient itself. We introduce here the Targeted Detectability Range (TDR), designed to evaluate with minimal computational effort the detectability of compact binary coalescences under the hypothesis of association with an external messenger, such as an electroMAGNETic or neutrino signal. Unlike the standard GW range, which is based on averaged source parameters, the TDR incorporates prior information from observations of the external messenger, including sky localization, inclination constraints, and physically motivated bounds on component masses. We report the detectability range of all GAMMA-RAY BURSTs, short and long duration, observed during the first three observing runs of the LIGO-Virgo-KAGRA collaboration. The method is validated by performing a systematic comparison with the 90$\%$ exclusion distances provided by modeled targeted GW searches.
[abstract 18 / 46] (score: 3) - Title: Self-Supervised ConvLSTM for FERMI Large Area Telescope Transient DetectionAuthors: Alberto Garinei, Stefano Speziali, Alessandro Vispa, Andrea Marini, Sara Cutini, Emanuele Piccioni, Marcello Marconi, Francesco Longo, Matteo Martini, Francesca Fallucchi, Romeo Giuliano, Ernesto William De Luca, Umberto Di Matteo, Sabino Meola,Comments: 17 pages, 5 figures. Accepted for publication in Astronomy and Computing. Author-accepted manuscript versionSubjects: astro-ph.HE astro-ph.IM cs.LGCreated: 2026-05-21; Updated: 2026-05-22; Datestamp: 2026-05-22
We present a framework for detecting transient gamma-ray phenomena in a controlled environment by combining end-to-end simulations of the FERMI-LAT sky with self-supervised spatio-temporal deep learning. We generate a ten-year synthetic Universe with gtobssim and process the simulated events into daily all-sky maps of counts and exposure, obtaining a time-ordered sequence that mirrors the structure of FERMI-LAT observations. To model the nominal evolution of the sky, we employ a Convolutional Long Short-Term Memory (ConvLSTM) network that operates directly on map sequences, preserving spatial locality while learning temporal dependencies. The model is trained to reconstruct expected emission, and departures from the learned baseline are quantified through pixel-wise mean-squared residual maps. We then define statistically motivated anomaly criteria by estimating per-pixel thresholds from the residual distribution on the training set, and we enforce spatial coherence via local filtering to suppress isolated fluctuations. The ConvLSTM is then deployed as trained predictor on FERMI-LAT daily maps, where the sky can depart from the nominal behavior because of genuine astrophysical variability and instrumental non-stationarities. The resulting pipeline flags localized, time-dependent excesses consistent with high-variable sources or transient events (e.g., flares or GRBs) and provides a benchmark for evaluating anomaly-detection strategies on long-duration, FERMI-LAT-like datasets.
[abstract 19 / 46] (score: 3) - Title: Nature of 4FGL J2249.4+6229: Evidence for a redback system with a cool companion and low X-ray and $γ$-ray luminositiesAuthors: A. V. Karpova, D. A. Zyuzin, S. V. Zharikov, M. R. Gilfanov,Comments: 8 pages, 5 figures, accepted for publication in MNRASSubjects: astro-ph.HECreated: 2026-05-21; Updated: 2026-05-22; Datestamp: 2026-05-22
We report the identification of the likely X-ray and optical counterpart to the unassociated FERMI source 4FGL J2249.4+6229. To clarify its nature, we investigate the X-ray data from SWIFT/XRT and SRG/eROSITA as well as photometric data from optical catalogues and archival spectroscopic data from the Gemini-North telescope. Using Zwicky Transient Facility data spanning over 6.6 yr, we confirmed a period of $\approx$5.6 h likely associated with the orbital motion in a binary system. The folded light curves have a smooth sinusoidal shape with two peaks per period and the amplitude of $\approx$0.2 mag. The X-ray spectra of the source are well fitted by an absorbed power law with the photon index of $\approx$2.0 and unabsorbed flux of $\approx$1.4$\times10^{-13}$ erg s$^{-1}$ cm$^{-2}$. All these together with the X-ray to optical flux ratio of $\sim$0.2 implies that 4FGL J2249.4+6229 is a promising redback candidate. Fitting the optical light curves with the direct heating model, we obtained the companion mass of $\approx$0.5 M$_\odot$ and temperature of $\approx$3600 K implying an M-type star. This places it among the coldest and most massive companions known in redback systems.Optical spectra confirms the M-type star and shows the broad asymmetric H$α$ emission line. For the distance of 500--550 pc derived from the optical data, the source can be the redback with the lowest X-ray and $γ$-ray luminosities.
[abstract 20 / 46] (score: 3) - Title: Dynamics of Binary System around a Supermassive Black Hole :Binary Scattering and Eccentric vZLK OscillationsAuthors: Kei-ichi Maeda, Hirotada Okawa,Comments: 25 pages, 23 figuresSubjects: gr-qc astro-ph.GA astro-ph.HECreated: 2026-05-21; Updated: 2026-05-22; Datestamp: 2026-05-22
We study the dynamics of a binary orbiting a supermassive BLACK HOLE (SMBH), focusing on both binary scattering in unbound orbits and eccentric von Zeipel-Lidov-Kozai (vZLK) oscillations in bound orbits. The motion is described in a local inertial frame in Kerr spacetime, where tidal effects are encoded in the Riemann curvature. For unbound (parabolic and hyperbolic) orbits, we identify four scattering regimes-adiabatic, tidally affected, chaotic, and disruptive-depending on the binary semi-major axis. As the binary becomes softer, tidal interactions near periapsis lead to strong eccentricity excitation, large changes in the orbital parameters, and eventually chaotic behavior or tidal disruption, with a sensitive dependence on the argument of periapsis. For eccentric bound (elliptic) orbits, the vZLK mechanism differs qualitatively from the standard one, although the $z$-component of the angular momentum in the local inertial frame remains approximately conserved. The evolution proceeds on a dynamical timescale and exhibits step-like changes driven by repeated periapsis passages, which can be interpreted as a sequence of scattering events. We refer to this behavior as scattering-type vZLK oscillations. The rotation of the SMBH also modifies the oscillation profiles, although its effect is less significant than the dependence on the initial orbital parameters. These results suggest a unified picture of periapsis-driven tidal dynamics in galactic nuclei.
[abstract 21 / 46] (score: 3) - Title: Second stability region for gyrokinetics and the L-H transitionAuthors: R. J. J. Mackenbach, A. Zocco, P. Helander,Comments:Subjects: physics.plasm-phCreated: 2026-05-21; Updated: 2026-05-22; Datestamp: 2026-05-22
Using a simple circular tokamak geometry, we show the well-known `second stability region' of MHD-ballooning modes exists for linear gyrokinetics too -- whether electrostatic or electroMAGNETic -- and we suggest that the plasma enters this region in H-mode as a consequence of the bootstrap current and Shafranov shift altering the MAGNETic field, which may occur if the normalised pressure gradient is $α_{\rm MHD} \simgt 1$ and collisionality is low. By performing simulations in more realistic MAGNETic geometries, we demonstrate a large reduction in collisionless, electrostatic turbulent transport when going from density and temperature profiles typical of L- and H-mode, respectively. This reduction is shown to be a consequence of both the bootstrap current lowering the global MAGNETic shear, and the pressure gradient altering the local MAGNETic shear, pushing the plasma towards the second-stability region. A path connecting the L- and H-mode equilibria is constructed, along which the energy and particle fluxes exhibit non-monotonic behaviour as a function of the pressure gradient.
[abstract 22 / 46] (score: 3) - Title: A Three-Dimensional Tomographic Reconstruction of the Galactic Cosmic-Ray Proton DensityAuthors: Hanieh Zandinejad, Jakob Roth, Vo Hong Minh Phan, Gordian Edenhofer, Philipp Frank, Philipp Mertsch, Ralf Kissmann, Andrés Ramírez, Laurin Söding, Torsten A. Enßlin,Comments:Subjects: astro-ph.HE astro-ph.GACreated: 2026-05-21; Updated: 2026-05-22; Datestamp: 2026-05-22
Cosmic rays (CRs) are a ubiquitous non-thermal component of the interstellar medium (ISM). A data-driven three-dimensional (3D) map of their distribution is essential for understanding CR transport and constraining the spatial distribution of their sources. In this work, we reconstructed the 3D spatial distribution of the Galactic cosmic-ray proton (CRp) density. We model the diffuse gamma-ray emission arising from inelastic hadronic interactions between CRps and interstellar gas. Using a map of dust-correlated diffuse gamma-ray emission based on ten years of FERMI-LAT observations together with a three-dimensional gas density model, we infer the spatial CRp distribution through a morphological matching approach. The logarithmic CRp density field is described by a Gaussian process defined on a spherical-times-radial grid, while both the field and its correlation structure are inferred simultaneously using Iterative Charted Refinement. The posterior distribution of the reconstructed 3D CRp density field is approximated using geometric variational inference. The reconstructed CRp density exhibits a smooth but spatially structured distribution with a limited dynamical range across the Galactic disk. We find a moderate enhancement of the CRp density toward the inner Galaxy. The inferred normalization at the Solar position is consistent with local CR measurements by the AMS-02 instrument.
[abstract 23 / 46] (score: 2) - Title: Controlling the Transverse Multipole Components in RF Cavity Modes using the Azimuthal Modulation MethodAuthors: Laurence Wroe, Walter Wuensch, Robert Apsimon,Comments:Subjects: physics.acc-phCreated: 2026-05-20; Updated: 2026-05-22; Datestamp: 2026-05-22
Recent work introduced a systematic method for designing so-called azimuthally modulated RF cavities that support transverse MAGNETic modes composed of user-desired multipoles, enabling precision control of the magnitude and orientation of multipolar components in RF cavity design. This paper extends this method to practical implementation by deriving the multipolar expansion of the longitudinal electric field in such RF cavities with beam pipes, as well as the momentum change of ultra-RELATIVISTIC particles traversing these modes. The derived equations explicitly show the radial variation of the change in longitudinal and transverse momentum follows a polynomial rather than Bessel-function relationship. The expression for the longitudinal electric field is then compared to a field map obtained from the 3D electroMAGNETic simulation of an azimuthally modulated cavity designed to support a mode composed of monopole, dipole, and quadrupole components. Beam dynamics studies are presented to assess the derived expressions for the change in momentum, including the effects of relaxing the ultra-RELATIVISTIC assumption. Finally, two example applications are presented: the first demonstrates the removal of unwanted transverse multipoles to create a multipole-free accelerating structure with a single-port coupler, whereas the second illustrates the synthesis of desired multipoles to create an RF cavity that transforms the transverse distribution of a beam from Gaussian to uniform.
[abstract 24 / 46] (score: 2) - Title: Initial evaluation of miniature ultra-high-field commercial stellarator reactors with breeding external to resistive coilsAuthors: V. Queral, E. Rincon, A. de Castro, I. Fernandez-Berceruelo, I. Palermo, A. Moroño, V. Tribaldos, J. M. Reynolds, D. Spong, S. Cabrera, J. Varela,Comments: 27 pages, 11 figures, 4 tablesSubjects: physics.plasm-phCreated: 2026-05-21; Updated: 2026-05-22; Datestamp: 2026-05-22
The working parameters and challenges of ultra-high-field pulsed commercial stellarator reactors of small plasma volume with breeding external to resistive coils ($transposed$ stellarator) are studied. They may allow production of commercial heat and electricity in a tiny and simple device, and contribute to the knowledge on burning plasmas. The concept is based on the previous works (V. Queral et al.) performed for the high-field experimental fusion reactor i-ASTER (J. Fus. Energy 37 2018) and the recent Distributed Divertor concept (non-resonant divertor on the full toroid; J. Fus. Energy 44 2025). The present proposal is driven by the limitation on the minimum size of typical commercial stellarator reactors (~ space for internal breeding/shielding of SC coils). This limit is about 400 $\text{m}^3$ plasma volume, as deduced from e.g. ARIES-CS, ASTER-CP-(IEEE Trans. Plasma Sci. 52 2024) and Stellaris reactors. This fact, together with the accuracy and complexity of the systems, hinders quick iterations for the fast development of stellarator reactors. The concept is based on a pulsed high-beta large-aspect-ratio stellarator of small plasma volume (2-4 $\text{m}^3$) and ultra-high MAGNETic field (~ 10-20 T), composed by an external monolithic coil support and internal resistive coils (alike i-ASTER and UST_3 stellarators) of high neutron transparency, thermally-adiabatic conductors, a low-recycling Distributed Divertor to extract the heat power from ionized particles (pulse length ~ 5 $τ$E), low pulsed duty cycle of 1-5%, and liquid breeding material around and externally to the reactor core. Different cases and operating points are studied. The main elements, e.g. heat power on the Distributed Divertor, radiation lifetime, and the prospect of net electricity production are evaluated. The involved challenges, impacting the potential feasibility of the concept, are assessed.
[abstract 25 / 46] (score: 2) - Title: GW231123: Overlapping Gravitational Wave Signals?Authors: Qian Hu, Harsh Narola, Jef Heynen, Mick Wright, John Veitch, Justin Janquart, Chris Van Den Broeck,Comments: 8 pages, 3 figures. Accepted versionSubjects: gr-qc astro-ph.HECreated: 2026-05-21; Updated: 2026-05-22; Datestamp: 2026-05-22
The recently discovered gravitational wave event GW231123 was interpreted as the merger of two BLACK HOLEs with a total mass of 190-265 $M_\odot$, making it the heaviest such merger detected to date. Whilst much of the post-discovery literature has focused on its astrophysical origins, primary analyses have exhibited considerable discrepancies in the measurement of source properties between waveform models, which cannot reliably be reproduced by simulations. Such discrepancies may arise when an unaccounted overlapping signal is present in the data, or from phenomena that produce similar effects, such as gravitational lensing or overlapping noise artifacts. In this work, we analyse GW231123 using a flexible model that allows for two overlapping signals, and find that it is favoured over the isolated signal model with Bayes factors of $\sim 10^2 - 10^{4}$, depending on the waveform model. These values lie within the top few per cent of the background distribution. Similar effects are not observed in GW190521, another high-mass event. Under the overlapping signals model, discrepancies in the measurement of source properties between waveform models are largely mitigated. We also find that neglecting an additional signal in overlapping-signal data can lead to discrepancies in the estimated source properties resembling those reported in GW231123. Although the overlapping signal model provides a higher Bayesian evidence, the astrophysical prior probability of two short signals overlapping is low. However, we find that the two recovered sources show similar properties. This, taken with the higher evidence of the two signal model, suggests that gravitational lensing may provide an alternative explanation.
[abstract 26 / 46] (score: 2) - Title: Golden and Silver Dark Sirens for precise H0 measurement with HETDEXAuthors: Yixuan Dang, Ish Gupta, Robin Ciardullo, Erin Mentuch Cooper, Shiksha Pandey, Dustin Davis, Surhud More, Rachel Gray, Hsin-Yu Chen, Daniel J. Farrow, Caryl Gronwall, Donghui Jeong, Shun Saito, Donald P. Schneider, B. S. Sathyaprakash,Comments: updated to match with APJSubjects: astro-ph.CO gr-qcCreated: 2026-05-20; Updated: 2026-05-22; Datestamp: 2026-05-22
Gravitational waves (GWs) from compact binary coalescences are standard sirens that provide a direct measure of the source's luminosity distance, enabling an independent measurement of the Hubble constant (H0). While a bright siren -- a GW event with an identified electroMAGNETic (EM) counterpart -- provided the first such constraint, most detections, currently dominated by BLACK HOLE mergers, lack EM signatures. A measurement of H0 is still possible with these dark sirens by statistically associating GW events with galaxies in existing catalogs based on the sky localization. In this work, we explore the potential of two subsets of sirens: rare golden dark sirens, for which a single galaxy dominates the H0 posterior, and silver dark sirens, which are far more common but have a larger set of plausible host galaxies. Using the fifth internal data release of the Hobby-Eberly Telescope Dark Energy Experiment (HETDEX), we assess the suitability of the Visible Integral-field Replicable Unit Spectrograph (VIRUS) for spectroscopic follow-up of dark sirens. VIRUS exposures of the standard HETDEX depth provide precise redshifts and exquisite completeness within z = 0.2. After a single year of observations with the upgraded LIGO-A# network, the combined sample of golden and silver dark sirens with z < 0.2 and follow-up VIRUS observations can potentially yield a few-percent constraint on H0. Our predictions suggest that spectroscopic redshift surveys such as HETDEX can play a key role in realizing high-precision cosmology with dark sirens in the near future. Standard-siren distance measurements offer a critical, fully independent path to the local value of H0 to resolve the Hubble tension.
[abstract 27 / 46] (score: 2) - Title: Testing the Spacetime Geometry of Sgr A* with the Relativistic Orbit of S2 starAuthors: Parth Bambhaniya, Preet Dalal, Giovani H. Vicentin, Riccardo Della Monica, Elisabete M. de Gouveia Dal Pino, Bina Patel,Comments: Accepted in the Phys. Dark Univ. (2026)Subjects: gr-qc astro-ph.GACreated: 2026-05-20; Updated: 2026-05-22; Datestamp: 2026-05-22
In this work, we perform a RELATIVISTIC test of the spacetime geometry of Sagittarius A* (Sgr A*) using the orbit of the S2 star. We consider a broad class of compact object models, including Schwarzschild, Reissner-Nordström, Bardeen, Hayward, and Simpson-Visser BLACK HOLEs, as well as the Janis-Newman-Winicour naked singularity spacetime. For each geometry, we integrate the timelike geodesic equations and consistently project the resulting trajectories onto astrometric and spectroscopic observables, incorporating Rømer time delay and RELATIVISTIC redshift effects. The theoretical predictions are tested with current Very Large Telescope (VLT) observations of the S2 star, while simultaneously imposing constraints from the Event Horizon Telescope shadow size. We find that several spacetimes that are degenerate at the level of shadow imaging, most notably Schwarzschild, Reissner-Nordström, and Bardeen regular BLACK HOLE geometries, remain statistically indistinguishable when tested against present S2 data. We further carry out a statistical model comparison based on the Akaike and Bayesian information criteria (AIC and BIC) to evaluate the relative performance of the alternative spacetime models. Our analysis also constrains the generalized charge like parameter $q/M$ in non-Schwarzschild spacetimes based on current S2 star observations, and identifies specific BLACK HOLE and horizonless geometries that can be further tested with forthcoming high precision astrometric observations from the VLT and Keck telescopes.
[abstract 28 / 46] (score: 2) - Title: High Sensitivity Methodologies to Detect Radio Band Gravitational WavesAuthors: Wei Hong, Peng He, Tong-Jie Zhang, Shi-Yu Li, Pei Wang,Comments: 50 pages, 24 figures, 5 tables. Matches the published version in ApJS. We present a simulation methodology and observing strategies for radio-band signals from graviton-photon conversion in pulsar magnetospheres, and assess FAST and SKA2-MID sensitivity using PSR J1856-3754 and PSR J0720-3125 as benchmarks. Of four observing strategies, MPMT performs bestSubjects: gr-qc astro-ph.CO astro-ph.HECreated: 2026-05-21; Updated: 2026-05-22; Datestamp: 2026-05-22
Gravitational waves (GWs) can resonate with MAGNETic fields through the Gertsenshtein-Zeldovich effect, producing electroMAGNETic signals at the same frequency. In pulsar MAGNETospheres, this conversion may yield a faint radio-band signal that could be detected. In this work, we focus on two specific pulsars, PSR J1856-3754 and PSR J0720-3125, and use numerical simulations to evaluate how well the FAST and SKA2-MID telescopes could detect such signals. We consider transient events, including primordial-black-hole-like mergers, as well as stochastic backgrounds, including primordial GWs. To improve detection sensitivity, we propose four observational methods to lower the detectable energy-density limit of very high-frequency (VHF) GWs; the "Multiple Pulsars with Multiple Telescopes" (MPMT) method performs best because it allows cross-validation and rejection of false candidates. Under the assumption of nearly 6000 hours of observation at 3 GHz and a $5σ$ detection threshold, the minimum detectable characteristic strain is projected to be $h_c \approx 10^{-23}$ for transient events and $h_c \approx 10^{-33}$ for stochastic backgrounds. Under optimistic assumptions on integration time and conversion efficiency, these projections suggest that radio-band searches may approach the sensitivity needed to begin testing representative VHF GW scenarios. More broadly, this conversion in pulsar MAGNETospheres could be relevant to the origin of some repeating fast radio bursts in the our galaxy.
[abstract 29 / 46] (score: 2) - Title: Rapid-response 1.3 mm Observations of GRB 260127A with the Submillimeter ArrayAuthors: Garrett K. Keating, Tanmoy Laskar, Anna Y. Q. Ho, Peter K. Blanchard, Kate D. Alexander, Edo Berger, Mark Gurwell, Tarraneh Eftekhari, Chloe T. Xu, Joshua Bennett Lovell, Ramprasad Rao, Peter K. G. Williams,Comments: Accepted for publication in ApJL; 7 pages, 3 figures (v2: updated references)Subjects: astro-ph.HE astro-ph.IMCreated: 2026-05-21; Updated: 2026-05-22; Datestamp: 2026-05-22
We present the results from rapid-response 1.3 mm observations of GRB 260127A using the Submillimeter Array (SMA). SMA arrived on-source 12.6 minutes after the initial detection by the Neil Gehrels SWIFT Observatory, representing the earliest millimeter/submillimeter observations of a GRB to date. From these observations, we find a source with flux density $6.9\pm1.7$ mJy, consistent with the X-ray afterglow position but slightly offset from the optical afterglow position (2.7'' offset, with the SMA detection having a 90% confidence radial position uncertainty of 0.9''). Subsequent observations 1.9 days later show no sources of emission, with a $3σ$ upper limit of 0.70 mJy. If the SMA detection is associated with GRB 260127A, we infer that the 1.3 mm light curve for GRB 260127A declined at least as fast as $t^{-0.5}$, suggesting that peak brightness of the event at this wavelength was reached in under a day. We discuss how these findings may be consistent with both forward shock and reverse shock afterglow scenarios, and implications for future millimeter/submillimeter observations of GRBs on these timescales.
[abstract 30 / 46] (score: 2) - Title: What causes the MAGNETic curvature drift?Authors: Johnathan K. Burchill,Comments: 4 pages, 1 figure. Accepted 21 May 2026 for publication as a Tutorial in Open Transport (de Gruyter Brill)Subjects: physics.gen-ph physics.plasm-phCreated: 2026-05-21; Updated: 2026-05-22; Datestamp: 2026-05-22
When asked what causes the MAGNETic curvature drift of a charged-particle moving in a curving MAGNETic field, people respond that there is an `F-cross-B' motion of the `guiding center' due to the centrifugal force on the particle as it follows the MAGNETic field line. This and similar explanations `beg the question' by assuming that the particle follows the field line. In a curving MAGNETic field, however, a particle moving parallel to the field direction soon won't be. The convective rotation of the field along the particle trajectory ensures that the Lorentz force switches on, and the resulting acceleration rotates the velocity vector back into alignment periodically. The gyration is not symmetric about the field vector, and the resulting velocity offset is the curvature drift. This explanation is guided by Newton's second law of motion in vector notation. It provides a common framework for explaining the three guiding-center motions of a charged particle in a static nonuniform MAGNETic field: curvature drift, mirror reflection in a MAGNETic bottle, and gradient-B drift. The discussion aims to provide insight to instructors of electricity and MAGNETism or plasma physics at the intermediate- to advanced-undergraduate level.
[abstract 31 / 46] (score: 2) - Title: Merger remnant and eccentricity dynamics surrogates for eccentric nonspinning BLACK HOLE binariesAuthors: Adhrit Ravichandran, Peter James Nee, Keefe Mitman, Tousif Islam, Scott E. Field, Vijay Varma, Michael Boyle, Andrea Ceja, Nils Deppe, Noora Ghadiri, Lawrence E. Kidder, Prayush Kumar, Marlo Morales, Jordan Moxon, Kyle C. Nelli, Harald P. Pfeiffer, Antoni Ramos-Buades, Katie Rink, Hannes R. Rüter, Mark A Scheel, Md Arif Shaikh, Leo C. Stein, Daniel Tellez, William Throwe, Nils L. Vu,Comments: 17 pages, 14 figures, 1 appendixSubjects: gr-qc astro-ph.HECreated: 2026-05-20; Updated: 2026-05-22; Datestamp: 2026-05-22
Accurate models of merger remnants are increasingly important for gravitational-wave science, including precision tests of gravity with ringdown, inference of black-hole populations, and modeling hierarchical mergers. For eccentric binaries, remnant mass, spin, and recoil carry nontrivial imprints of eccentricity that are both physically informative and more challenging to model, yet remain less developed than in the quasi-circular case. We present two new models trained on numerical-relativity (NR) simulations of unequal-mass, non-spinning eccentric binary BLACK HOLEs: NRSurE_q4NoSpin_Remnant, which predicts remnant properties, and NRSurE_q4NoSpin_Dynamics, a time-domain surrogate for the evolution of eccentricity and mean anomaly. Both models are trained on NR simulations over a three-dimensional parameter space with mass ratios $q \leq 4$, eccentricity $e < 0.23$, and mean anomaly $\ell \in [0,2π)$ radians, where both $e$ and $\ell$ defined at $t=-1000M$ relative to peak amplitude and $M$ is the total mass. We highlight some applications, including the phenomenological impact of eccentricity on remnant properties and the enhancement or suppression of recoil. We also provide error estimates for all modeled quantities, supporting reliable use in current and future gravitational-wave parameter-estimation analyses. Both models will be made available through open-source codes.
[abstract 32 / 46] (score: 2) - Title: The one and the only: the pulsar - white dwarf system in NGC 6749Authors: Paulo C. C. Freire, Yinfeng Dai, Mario Cadelano, Cristina Pallanca, Zurong Zhou, Zhichen Pan, Luca Rosignoli, Davide Massari, Mattia Libralato and, Craig Heinke,Comments: 8 pages, 4 figures, two tables. Accepted for publication in Astronomy & AstrophysicsSubjects: astro-ph.HECreated: 2026-05-21; Updated: 2026-05-22; Datestamp: 2026-05-22
PSR J1905+0154A is a binary millisecond pulsar located in the globular cluster (GC) NGC 6749. It was discovered in 2004 in a search for pulsars in GCs carried out with the Arecibo 305-m radio telescope. The pulsar has a spin period of 3.2 ms, an orbital period of 0.81 days, and is in a low-eccentricity orbit with a low-mass WD companion. Combining early Arecibo and latter Five Hundred meter Aperture Spherical Telescope (FAST) data, we were able to derive a phase-coherent timing solution for this pulsar, which now spans 20 years. This includes a precise measurement of the astrometric, spin and orbital parameters of the system. The small range of predicted accelerations expected from the gravitational field of this GC allows an estimate of the intrinsic spin-down: the inferred MAGNETic field at the surface (2.2 - 2.4 * 10^8 G) and characteristic age (2.8 - 3.5 Gyr) are typical of what one finds among MSPs in the Galactic field. The position of this pulsar coincides with the position of one of the very few candidate white dwarfs (WDs) in the whole HST dataset on this GC. The position of the companion in the colour-magnitude diagram is consistent with a Helium WD with a mass of 0.17 - 0.19 M_sun, a cooling age of 0.4 - 0.7 Gyr, and a surface temperature of 11,600 - 14,800 K. A comparison with the characteristic age of the pulsar indicates that at the time of Roche lobe detachment, the spin period was between 1.98 and 2.62 ms.. The velocity of the system relative to the GC, which is 4.5-sigma significant and an order of magnitude larger than the escape velocity, raises the possibility that, despite its location close to the centre of the GC, the pulsar might not be associated with it. Finally, our effort to confirm a second pulsar candidate in this GC did not yield a positive confirmation, nor the discovery of any additional pulsar in this GC.
[abstract 33 / 46] (score: 2) - Title: Astrophysical Signature and Optical Appearance of Weyl--Corrected Einstein--Maxwell Black HolesAuthors: Hassan Hassanabadi, Mrinnoy M. Gohain, Kalyan Bhuyan, Farokhnaz Hosseinifar,Comments: 27 pages, 20 figures and 1 table. Comments and suggestions are welcomeSubjects: gr-qc hep-thCreated: 2026-05-20; Updated: 2026-05-22; Datestamp: 2026-05-22
In this work, we delve into the physics of charged BLACK HOLEs modified by Weyl corrections, a framework that emerges from the subtle non--minimal coupling between spacetime curvature and electroMAGNETism. We begin by revisiting the thermodynamics of these cases, where we derive the Hawking temperature, entropy, and heat capacity to see how the Weyl correction parameter reshapes the landscape of thermal stability and phase transitions. Then, we apply the winding number method to classify the thermodynamic states of the system from a topological perspective and show the effect of the Weyl modifications on the universal classification of the Wey--corrected BLACK HOLE. Moving beyond pure theory and into the realm of astrophysics, we study the motion of massless particles affected by the Weyl correction for the two photon POLARIZATION, and by exploring the shadow, we find constraints of the BLACK HOLE parameters. Also, we study the null trajectories for the two photon POLARIZATION of the Weyl--corrected BLACK HOLE. Finally, we model the accretion disk around these BLACK HOLEs. By calculating the energy flux, spectral luminosity, and differential luminosity, we show how these corrections leave a detectable trace on the light we might observe.
[abstract 34 / 46] (score: 2) - Title: Predicting intermediate-mass BLACK HOLE formation in star clusters with machine learningAuthors: Konstantinos Kritos, Digvijay Wadekar, Emanuele Berti,Comments: 28 pages, 13 figuresSubjects: astro-ph.GA astro-ph.CO astro-ph.HE gr-qcCreated: 2026-05-20; Updated: 2026-05-22; Datestamp: 2026-05-22
Whether intermediate-mass BLACK HOLEs reside in nearby star clusters has remained contested for decades. We address this question by training neural network and random forest regressors on synthetic catalogs generated with the {\sc Rapster} cluster evolution code, mapping observable cluster properties such as total mass and half-mass radius onto the mass of the heaviest BLACK HOLE built up through repeated mergers. Applying these models to nearby globular and nuclear star clusters, we forecast the intermediate-mass BLACK HOLE population that each system may host. Globular clusters are unlikely to contain BLACK HOLEs more massive than $\sim 100\,M_\odot$, with an occupation fraction near 0.02, although they can produce remnants within the upper mass gap with masses approaching $100\,M_\odot$. Among nuclear star clusters, a handful of cases, including NGC 5102 and NGC 5206, yield predicted central BLACK HOLE masses above $100\,M_\odot$, which we contrast with kinematically inferred estimates. Where the observationally claimed masses exceed our predictions, the implication is that the assembly history involved processes beyond hierarchical mergers, most plausibly accretion of gas and stars. Finally, we employ a normalizing flow to quantify, for individual globular clusters, the likelihood that their initial conditions were favorable to a collisional runaway during the first few million years after formation.
[abstract 35 / 46] (score: 2) - Title: Pfirsch-Schlüter CurrentAuthors: Allen H Boozer,Comments:Subjects: physics.plasm-phCreated: 2026-05-20; Updated: 2026-05-22; Datestamp: 2026-05-22
The Pfirsch-Schlüter current is a current that flows along the MAGNETic field lines in a toroidal plasma equilibrium that is required to make the plasma current density divergence free in the presence of a plasma-pressure gradient. A distortion in the plasma shape is caused by the Pfirsch-Schlüter current, and it is desirable to minimize both the strength and the distance this current flows along the MAGNETic field lines. The Pfirsch-Schlüter current is localized within a half period of a stellarator when $d\ell/B$ integrated over the half period is the same for all lines in the MAGNETic surface. It is shown that within parts in a thousand this is the same condition as the distance $\ell_{p/2}$ required for a field line to cross the half period being the same for all lines in the surface. To make the $\ell_{p/2}$'s the same, the lines started on the small major radius side of the plasma must undergo wiggles to make their $\ell_{p/2}$ as long as those started on the outboard side. This is achievable either using modular coils with a large helical component on the small major radius side or with a central column carrying a helical current.
[abstract 36 / 46] (score: 2) - Title: Numerical simulations of shock-driven, supersonic turbulence in colliding three-temperature laboratory plasmasAuthors: Stefano Merlini, James R. Beattie, Vicente Valenzuela-Villaseca,Comments: Main: 24 pages, 17 figures. Appendix: 5 pages, 2 figures. Submitted to ApJSubjects: physics.plasm-ph astro-ph.GA astro-ph.HE physics.flu-dynCreated: 2026-05-20; Updated: 2026-05-22; Datestamp: 2026-05-22
Shock-driven turbulence is central to astrophysical plasmas in which explosions and compressive driving inject energy through shocks rather than steady stirring. We present three-dimensional, three-temperature (ion, electron, and radiation; 3T) radiation-hydrodynamic simulations of a laboratory platform in which two offset CH mesh targets are irradiated by a $30\,\rm ns$ X-ray pulse. Mesh ablation launches counter-streaming supersonic flows whose vorticity is seeded baroclinically at mesh-cell corners, advected into collimated channels over $\sim15\,\rm ns$, and injected into the outgoing streams before collision. The flows first collide at $t\simeq75\,\rm ns$, forming a shocked turbulent mixing layer that persists for at least $300\,\rm ns$, reaches $\ell_0\simeq4.5\,\rm mm$, and evolves toward an effectively isothermal equation of state with $γ_{\rm eff}\simeq1.1$. After stagnation, $u_0(t)\propto t^{-1.1}$ while $t_0/t_{c_s}\simeq0.2$ remains nearly fixed. Compression and stretching dominate the vorticity budget, and the velocity field relaxes toward a kinetic-energy partition of approximately $70\%$ solenoidal and $30\%$ compressive. The Reynolds stress is strongly anisotropic at the outer scale and remains measurably anisotropic over much of the resolved inertial interval, indicating directional memory of the collision axis and mesh geometry across many scales. The solenoidal strain spectrum implies $\ell_{ν,\rm s}\simeq92\,μ\rm m$, $\ell_0/\ell_{ν,\rm s}\simeq49$, and an effective Reynolds number $\mathrm{Re}\sim2\times10^2$. The density-gradient spectrum is directly tied to the compressive mode spectrum, which evolves independently from the incompressible cascade. Abridged.
[abstract 37 / 46] (score: 2) - Title: Optical analogy for stellarators: Ridges as caustics and coils as singularitiesAuthors: Wrick Sengupta, Stefan Buller, Rogerio Jorge, John Kappel, Andrew Brown, Richard Nies, Pedro F. Gil, Nikita Nikulsin, Per Helander, Amitava Bhattacharjee,Comments:Subjects: physics.plasm-phCreated: 2026-05-20; Updated: 2026-05-22; Datestamp: 2026-05-22
A common feature of most numerically optimized stellarator geometries is the presence of sharp ridges on outer flux surfaces, irrespective of the rotational transform. Despite their importance, an analytical theory for their existence has been lacking. In this work, we demonstrate that ridges are not artifacts but mathematical necessities. We develop such a theory for devices with quasisymmetry (QS). We demonstrate that QS exhibits close connections with the theory of geometrical optics, following Parker's ``optical analogy" (E.N. Parker, Geophys. Astrophys. Fluid Dyn, 1989). By mapping vacuum QS to the eikonal equation of geometrical optics, we derive the conditions for ridge formation, identified as field line caustics where MAGNETic field lines focus. Furthermore, we prove a geometric theorem for stellarator coil design: both ridges and filamentary coils must lie on the zero-determinant manifold of the MAGNETic gradient tensor. This topological constraint unifies the description of plasma ridges and external coils, providing a precise criterion for identifying valid coil locations and explaining the efficacy of the MAGNETic gradient lengthscale (J. Kappel et al., Plasma Phys. Control. Fusion, 2024) as a coil optimization parameter. We demonstrate that as the device becomes more compact, sharp ridges naturally form on the inboard side in quasiaxisymmetry. We support our analytical theory with extensive numerical evidence.
[abstract 38 / 46] (score: 2) - Title: Powerful Radio Sources in the Southern Sky. IV. Observations of the G4Jy-3CRE Catalog with the Australian Square Kilometre Array PathfinderAuthors: Siegfried A. Gawenda, Juan P. Madrid, Francesco Massaro, Sara V. White, C. C. Cheung, Chiara Mazzucchelli, Abigail García-Pérez, I. Andruchow, Vahram Chavushyan, Ralph Kraft, Victoria Reynaldi, Ana Jimenez-Gallardo, Alessandro Capetti, Barbara Balmaverde, William R. Forman, H. A. Peña-Herazo, Nicole Nesvadba, Sergio A. Cellone, Romana Grossová, Alessandro Paggi, Eleonara Sani, C. Leto,Comments:Subjects: astro-ph.GACreated: 2026-05-21; Updated: 2026-05-22; Datestamp: 2026-05-22
A recent 2023 paper by Massaro et al. introduced the G4Jy-3CRE, a new catalog of the brightest radio sources in the southern hemisphere that serve as a southern equivalent to the Third Cambridge Catalog Revised (3CR). The G4Jy-3CRE catalog selected 264 sources from the GLEAM-4Jy survey based on the same criteria used to select the sources in the 3CR. In this paper, we present new Australian Square Kilometre Array Pathfinder (ASKAP) continuuum imaging of the G4Jy-3CRE catalog. We use the three most recent data releases from the Rapid ASKAP Continuum Survey (RACS), covering the sky south of +30°decl.: RACS-low1, RACS-mid, and RACS-high. Together, these data releases cover a range of frequencies from 600 to 1800 MHz. The RACS surveys have improved spatial resolution and sensitivity over archival surveys at the same frequency, enabling us to classify 173 sources (66% of the sample) with morphologies indicative of the presence of JETs, 37 of which did not show JET activity on archival radio maps. We were able to effectively classify FRI/FRII galaxies up to a redshift of z = 1.35. Moreover, we identified six optical counterparts for sources that were either previously unidentified or ambiguous.
[abstract 39 / 46] (score: 2) - Title: Water vapor buoyancy and the African easterly JETAuthors: Heng Quan, Da Yang, William Boos, Tiffany Shaw, Huazhi Ge, Yaoxuan Zeng, Carly KleinStern,Comments:Subjects: physics.ao-phCreated: 2026-05-21; Updated: 2026-05-22; Datestamp: 2026-05-22
The African easterly JET (AEJ) is a prominent circulation feature in the tropical atmosphere. It transports mineral dust and generates easterly waves that serve as seeds for hurricanes. Conventional wisdom holds that the AEJ is in thermal wind balance with the positive meridional temperature gradient over North Africa. Here, using reanalysis data, we show that the negative meridional moisture gradient substantially counteracts the effect of the temperature gradient on density in that balance, diagnostically accounting for a 30\% reduction of the AEJ magnitude. Using CMIP6 data, we further show that this effect of vapor buoyancy on the AEJ strengthens under global warming, highlighting the critical role of the spatial distribution of moisture on large-scale circulation. Analysis of the AEJ in CMIP6 models confirms that some models do not include vapor buoyancy in their governing equations, raising questions about the relevance of their projections of climate change in that region.
[abstract 40 / 46] (score: 2) - Title: Quantitative Black Hole Imaging Laboratory with the Black Hole Vision App: I. Schwarzschild SpacetimeAuthors: Lior M. Burko,Comments: 12 pages, 2 figuresSubjects: gr-qc physics.ed-phCreated: 2026-05-21; Updated: 2026-05-22; Datestamp: 2026-05-22
This paper utilizes the {\it Black Hole Vision} smartphone application to catalyze a pedagogical shift in General Relativity education through the quantitative analysis of simulated BLACK HOLE imaging. Presented here for the Schwarzschild spacetime, the investigation is designed with a hierarchical modularity suitable for undergraduate students, with an expanded version intended for graduate courses in General Relativity or Relativistic Astrophysics. By transforming the mobile device into an educational RELATIVISTIC imaging tool, we triangulate the simulated Schwarzschild mass through independent probes and characterize anisotropic coordinate transformations via a Jacobian map. Global numerical consistency is investigated through integrated coordinate length, while the exponential instability of nearly bound orbits is quantified through a measurement of the simulated Lyapunov exponent. Finally, symmetry is constrained through a sub-pixel constraint on eccentricity in the simulated spacetime. By integrating this statistical framework, the paper enables students to explore the distinction between physical signatures and instrumental noise using established metrological protocols.
[abstract 41 / 46] (score: 2) - Title: Fast ion effects on the threshold conditions of ion temperature gradient mode and electron temperature gradient modeAuthors: Min Ki Jung, Taik Soo Hahm, Yong-Su Na, Eisung Yoon,Comments:Subjects: physics.plasm-phCreated: 2026-05-21; Updated: 2026-05-22; Datestamp: 2026-05-22
We investigate the fast ion effects on the threshold conditions of ion temperature gradient (ITG) mode and electron temperature gradient (ETG) mode both analytically and numerically using gyrokinetic equation. The onset condition for ITG mode shows a strong and monotonic favorable dependence on the fraction of fast ions, and mostly favorable but non-monotonic dependence on the fast ions' normalized temperature $T_f/T_i$ ($T_f$ is the effective temperature of fast ions, $T_i$ is the temperature of thermal ions). Overall favorable parametric trends are consistent with those for the linear growth rate reported in previous papers, as they are largely determined by kinetic wave-particle resonance effects. While general analytic expressions for the critical normalized thermal ion temperature gradient scale length $(R/L_{T_i})_c$ are quite complicated, an explicit compact expression $\left(\frac{R}{L_{T_i}}\right)_c=\left(\frac{4}{3}+\frac{3}{2}\sqrt{\fracπ{2}}\frac{|\hat{s}|}{q}\right)\left(1+\frac{T_i}{Z_i(1-f_h)T_e}\right)$ has been derived for the mode with its perpendicular scale larger than thermal ion gyroradius, but much smaller than the fast ion gyroradius so that finite Larmor radius effects are manifested in opposite asymptotic limits depending on ion species when $T_f\gg T_i$, and weak density gradient. Here, $q$ is safety factor, $\hat{s}$ is MAGNETic shear, $Z_i$ is thermal ions' charge, and $f_h$ is fast ion charge density fraction. In this limit, only the fast-ion-induced thermal ion dilution effects persist as fast ion density response becomes unMAGNETized and negligible. On the other hand, the fast ion effects on ETG-threshold are found to be unfavorable.
[abstract 42 / 46] (score: 2) - Title: On the Shafranov shift in stellaratorsAuthors: Per Helander, Nikita Nikulsin,Comments: 15 pages, 7 figures. Submitted to Journal of Plasma PhysicsSubjects: physics.plasm-phCreated: 2026-05-21; Updated: 2026-05-22; Datestamp: 2026-05-22
As first shown by Shafranov, toroidal plasmas in MAGNETohydrodynamic equilibrium tend to expand in major radius when the pressure is increased. Here, an average measure of the resulting Shafranov shift is introduced, and its properties are discussed for various classes of optimised stellarator configurations. It is shown to be particularly small in quasi-helical and quasi-isodynamic stellarators with a large number of field periods, which are thus particularly robust to variations in the plasma pressure.
[abstract 43 / 46] (score: 2) - Title: JWST observations of a planetary nebula support JET-driven explosion of core-collapse SUPERNOVA remnant RCW 103Authors: Aleksei Klimov, Noam Soker,Comments: It will be submitted in two days to allow for comments (including missing references)Subjects: astro-ph.HECreated: 2026-05-21; Updated: 2026-05-22; Datestamp: 2026-05-22
We show that the morphology of the core-collapse SUPERNOVA (CCSN) remnant RCW 103 is very similar to the morphology of the brightest regions in the recently released JWST IR images of the JET-shaped planetary nebula (PN) PMR 1, and conclude that two energetic pairs of JETs shaped RCW 103, compatible with the jittering-JETs explosion mechanism (JJEM). The PN PMR 1 IR image exhibits two opposite, large, and prominent ears with a narrow, faint region connecting them through the center, a pipe. Observations and simulations have shown that a pair of JETs inflates such a pair of ears in PNe. The brightest regions of PN PMR 1 form two clumpy sectors, each shaped like a wide pizza slice, with a faint region between them; the CCSN remnant RCW 103 has a very similar morphology. We identify two shells in the X-ray image of RCW 103 and suggest that two close pairs of energetic JETs shaped this CCSN remnant. We find only traces of two of the four expected ears in RCW 103. The ears in RCW 103 were already dispersed and are very faint. Deeper X-ray observations might detect them. Such energetically misaligned pairs of JETs are compatible with the JJEM, which predicts that a few to about 20 pairs of JETs are responsible for most CCSN explosions.
[abstract 44 / 46] (score: 2) - Title: Experimental investigation of twin pulsed JETs in a hemispheric elastic cavityAuthors: L. S. Merlo, L. Kadem, W. Saleh, H. D. Ng, G. Di Labbio,Comments: 21 pages, 9 figures, journal articleSubjects: physics.flu-dynCreated: 2026-05-21; Updated: 2026-05-22; Datestamp: 2026-05-22
This study experimentally examines the impact of spacing between two pulsed JETs and their strengths on the fluid dynamics within an elastic hemispherical cavity. Such interactions between multiple pulsed JETs are observed in various natural and industrial contexts, including cardiovascular flows, where they occur naturally within the atria or result from medical interventions (e.g., mitral valve repair, mechanical heart valves, paravalvular leaks) or diseases (e.g., aortic or pulmonary valve regurgitation). Fundamentally, these flows usually feature two or more pulsed JETs interacting in an expanding, elastic environment. In this investigation, the experimental setup features two parallel pulsed JETs entering the cavity, with JET strength varied across five formation times (1, 2, 3, 4, 5) and four spacing ratios (1.5, 2.0, 2.5, 3.0). Time-resolved particle image velocimetry is used to capture the instantaneous velocity fields. The results reveal three distinct flow regimes: short-time decay, decay at the wall, and wall rebound with or without the formation of secondary vortices. These findings uncover rare aspects of twin vortex ring behavior, including symmetry breaking, trajectory shifts, and wall-induced rebound mechanisms, with direct relevance to cardiac fluid dynamics in both healthy and pathological conditions.
[abstract 45 / 46] (score: 2) - Title: Dimming of Photon Ring due to Photon-Axion Conversion around Kerr Black HolesAuthors: Rahul Dhyani, Sauvik Sen, Indrani Banerjee, Ashmita Chakraborty, Arindam Chatterjee,Comments: 48 pages, 13 figures, 3 tablesSubjects: gr-qc astro-ph.HE hep-phCreated: 2026-05-21; Updated: 2026-05-22; Datestamp: 2026-05-22
We investigate photon-axion conversion in the vicinity of rotating Kerr BLACK HOLEs where strong gravity traps photons on near-circular trajectories, effectively enhancing the path length. We explore the observable signatures of such a conversion near the photon region. The process, driven by ambient MAGNETic fields, is significantly more efficient around supermassive BLACK HOLEs such as M87*, since the luminosity of photons increases with the mass of the BH. By numerically evaluating photon path lengths (on which the conversion depends), we analyze how key parameters-photon frequency, axion mass, photon-axion coupling, MAGNETic field strength, plasma density, and BLACK HOLE spin-affect the conversion probability and the resultant dimming of photon spectral luminosity. We find that the conversion is most efficient at high frequencies (X-rays and gamma rays), while the frequency window associated with efficient conversion widens with an increase in the photon-axion coupling and a decrease in the electron density and the axion mass. The magnitude of dimming of the photon spectral luminosity depends primarily on the MAGNETic field, the photon-axion coupling and the BH spin. Our study reveals that rotating BLACK HOLEs generally exhibit enhanced dimming compared to static ones. Thus, if future telescopes achieving a resolution $\sim 10^{-5}$ arcsec in the X-ray/gamma-ray band detect a dimming of the photon spectral luminosity, then they can provide interesting constraints on the axion mass and its coupling with photons.
[abstract 46 / 46] (score: 2) - Title: Dynamics of fast MAGNETosonic wave turbulenceAuthors: Nicolás Pablo Müller, Sébastien Galtier,Comments:Subjects: physics.plasm-ph physics.flu-dynCreated: 2026-05-21; Updated: 2026-05-22; Datestamp: 2026-05-22
Fast MAGNETosonic waves are among the fundamental oscillation modes of astrophysical plasmas. To study their dynamics, we carry out numerical simulations of the wave turbulence kinetic equation, which describes the evolution of the energy spectrum of a set of weakly nonlinear fast MAGNETosonic waves. This kinetic equation, which involves three-wave interactions, has recently been derived from compressible MAGNETohydrodynamics in the low-$β$ limit (Galtier 2023). It has an exact stationary solution, the Kolmogorov-Zakharov spectrum, corresponding to a direct energy cascade. Here we perform free decay simulations of the kinetic equation for which we propose a Kolmogorov-type phenomenology to explain the temporal decay laws of energy and integral length scale. In the forced simulations, we show that the cascade is in fact composed of a mixture of a forward cascade for counter-propagating waves, and a backward cascade for co-propagating waves, with the former being stronger than the latter. The Kolmogorov-Zakharov energy spectrum in $k^{-3/2}$ is found in the radial direction with an anisotropy due to the amplitude that depends on the angle relative to the strong mean MAGNETic field. We give the analytical expression of the Kolmogorov-Zakharov constant, which is numerically verified in the high Reynolds number limit. Our study provides a theoretical explanation for certain observations in the solar wind plasma (Zhao et al. 2022), where a regime of weak turbulence has been identified for fast MAGNETosonic waves, alongside a critical balance regime for strong Alfvén wave turbulence.
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