Current date: 2026-05-18
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Datestamp limit: 2026-05-18 (0 days ago)
Created/updated limit: 2026-05-11 (7 days ago)
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Scoring abstracts
Number of records retrieved: 589
Keyword score statistics
score 15 -- 1 abstracts
score 12 -- 1 abstracts
score 9 -- 1 abstracts
score 8 -- 3 abstracts
score 6 -- 1 abstracts
score 5 -- 2 abstracts
score 4 -- 4 abstracts
score 3 -- 7 abstracts
score 2 -- 11 abstracts
in total -- 31 abstracts
Articles that appeared on 2026-05-18
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[abstract 1 / 31] Wow! (score: 15)
- Title: Spectral-Regime Overlap and Transition-like Behavior in the Blazar Population from Multi-Instrument X-ray and TeV ObservationsAuthors: Javaid Tantry, Naseer Iqbal,Comments: 30 pages, 12 figures, 7 tables, comments are welcomeSubjects: astro-ph.HECreated: 2026-05-15; Updated: 2026-05-18; Datestamp: 2026-05-18
Blazars are conventionally classified into BL Lac objects and flat-spectrum radio QUASARs (FSRQs), commonly associated with radiatively inefficient and efficient accretion onto supermassive BLACK HOLEs, respectively. Increasing evidence, however, suggests that this division is not strictly discrete, with several sources occupying intermediate or transition-like spectral states. Since the photon index traces the evolution of the non-thermal emission spectrum, it provides a useful probe of JET energetics, particle acceleration, and radiative processes across BLAZAR populations. Using multi-mission observations from SWIFT-XRT, SWIFT-BAT, NUSTAR, ROSAT, Chandra, XMM-Newton, NICER, AstroSat, TeVcat, and archival VizieR compilations, we investigate the distribution and long-term evolution of X-ray and TeV photon indices across multiple BLAZAR subclasses. We identify broad overlap regions in photon-index space linking EHBL, HBL, IBL, LBL, and FSRQ-like populations, suggesting a continuous rather than sharply separated spectral distribution. Across X-ray instruments, the intermediate regime is concentrated near $Γ_{\mathrm{X}} \approx 2$, typically spanning $Γ_{\mathrm{X}} \sim 1.5$--$2.2$. Multi-epoch observations reveal substantial intra-source spectral evolution, including stochastic variability in Mrk~421 and state-dependent transitions in OJ~287. Several sources exhibit spectral-index changes of $ΔΓ_{\mathrm{X}} > 0.5$, while occupancy of the intermediate regime reaches $\sim22$--$43%$ depending on instrument. Multiple objects repeatedly traverse spectral regions connecting traditionally distinct subclasses, supporting their interpretation as candidate transition-like BLAZARs. Overall, the results favor a framework in which BLAZAR subclasses represent overlapping and evolving spectral populations driven by long-term changes in JET emission and radiative processes.
[abstract 2 / 31] Wow! (score: 12) - Title: Stern--Gerlach Spin Sorting in Relativistic Magnetic ReconnectionAuthors: K. Nykyri,Comments: 4 pages includiing two figures, supplementary material with 3 figuresSubjects: physics.plasm-ph astro-ph.HECreated: 2026-05-15; Updated: 2026-05-18; Datestamp: 2026-05-18
We introduce a Stern--Gerlach (SG) spin-kinetic control parameter for MAGNETic RECONNECTion. The fully projected branch parameter, $Ξ_0=
/r_L$ compares the SG cross-sheet displacement accumulated during a diffusion-region transit with the RELATIVISTIC Larmor radius. For an ensemble or partially participating population the relevant effective parameter is $Ξ_{\rm Eff}=P_{eff}Ξ_0$, where $P_{eff}$ represents the surviving branch weight or effective spin/moment projection. Evaluating $Ξ_{\rm Eff}$ across representative space and astrophysical environments reveals a robust hierarchy: SG transport is negligible in the MAGNETotail, solar corona, ACTIVE GALACTIC NUCLEi (AGN)/BLAZAR JETs, and pulsar-wind nebulae, but becomes transitional to strong in MAGNETar current sheets and extreme near MAGNETar surfaces. We further show, using electron--positron particle-in-cell simulations, that the SG force sorts particles by MAGNETic-moment projection into opposite sides of a Harris current sheet without measurably changing the global RECONNECTion rate in the tested regime. This identifies MAGNETars as the clearest natural target for strong-field spin-kinetic RECONNECTion ($Ξ_{\rm eff}\gg 1$) near the surface; transitional in the outer MAGNETosphere), while SG transport is safely negligible ($Ξ_{\rm eff}\ll 1$) in all heliophysical and JET environments considered, and provides a falsifiable framework for assessing where SG physics is relevant.
[abstract 3 / 31] Wow! (score: 9) - Title: Impacts of radiative cooling on the images of a BLACK HOLE shadow and extended JETs in two-temperature GRMHD simulationsAuthors: Mingyuan Zhang, Yosuke Mizuno, Indu K. Dihingia, Christian M. Fromm, Ziri Younsi, Hai Yang, Alejandro Cruz-Osorio,Comments: 16 pages, 14 figures. Accepted for publication in A&ASubjects: astro-ph.HECreated: 2026-05-15; Updated: 2026-05-18; Datestamp: 2026-05-18
The recent 230 GHz observations from the Event Horizon Telescope collaboration have successfully imaged the supermassive BLACK HOLE shadow of the M87 galaxy. However, the relatively high radiative efficiency observed in the hot accretion flow suggests that radiative cooling is non-negligible and should be considered when calculating the electron temperature. In this study, we compare accretion models without and with radiative cooling across a range of mass accretion rates, $\dot{M}_{\mathrm{BH}} = (1.0 - 10) \times 10^{-6}\,\dot{M}_{\mathrm{Edd}}$, aiming to assess the impact of cooling on the disk structure, electron temperature distribution (eDF), BLACK HOLE shadow morphology, broadband spectral energy distributions (SEDs), and flux variability. We performed general RELATIVISTIC radiative transfer (GRRT) calculations on two-temperature, radiative, general RELATIVISTIC MAGNETohydrodynamic (GRMHD) simulations, employing different electron heating prescriptions and nonthermal eDFs, analyzing the radiation transfer due to SYNCHROTRON emission at 230 GHz with inclination angle of $163^\circ$. These simulations are targeted toward M87$^{*}$. By comparing density profiles, eDFs, GRRT images, SEDs, and time variability between models, we find that the radiative cooling sharply decreases the electron temperature in the dense inner disk around the equatorial plane ($r\lesssim 10\,r_\mathrm{g}$), while slightly reducing JET sheath temperature. Cooling leads to a dimmer disk, more extended and brighter JETs, and reduced total flux. For a given accretion rate, cooling reduces the high-frequency flux. Time variability originates primarily from the midplane in both non-cooling and cooling cases and decreases as accretion rates rise. Although currently below the dynamic range of EHT observations, the features identified in this study could be resolved by next-generation arrays such as the ngEHT.
[abstract 4 / 31] Wow! (score: 8) - Title: Correlation Between X-Ray and Cosmic Neutrino Sources: From Obscured AGN to BlazarsAuthors: Emma Kun, Imre Bartos, Claudio Ricci, Santiago del Palacio, Francis Halzen, Julia Becker Tjus, Peter L. Biermann, Anna Franckowiak,Comments: 18 pages, 7 figures, 3 tables. Submitted to PASPSubjects: astro-ph.HECreated: 2026-05-14; Updated: 2026-05-18; Datestamp: 2026-05-18
The origin of high-energy astrophysical neutrinos remains a key open question in multimessenger astrophysics. A correlation between unabsorbed hard X-ray emission and high-energy neutrino luminosity has been reported in a sample of six ACTIVE GALACTIC NUCLEi with the highest individual IceCube significances, linking neutrino production to compact, photon-rich environments near supermassive BLACK HOLEs. In this work we study whether the threshold-near IceCube excesses associated with seven NUSTAR-observed BLAZARs are statistically consistent with that established relation. Calibrating the relation between the neutrino and hard X-ray luminosities as $\log L_ν= α+ β\log L_\mathrm{hX} + \mathcal{N}(0, σ_{\rm int}^2)$ on the six published sources via a Bayesian regression with errors on both axes, the recovered slope is consistent with $β= 1$, and the intrinsic scatter is $\sim 0.6$\,dex. All seven new BLAZARs are posterior-predictively consistent with this calibration ($χ^2_7 = 1.58$, $p = 0.98$) under the working hypothesis that the published IceCube best-fit neutrino numbers $\hat{n}_s$ values reflect the signal. A null-injection test confirms that, given the present calibration sample size, the consistency test does not by itself adjudicate between signal and selected-background origins. A distance-free $L_\mathrm{hX}/L_ν$ ratio diagnostic places both populations within the photohadronic prediction band, statistically indistinguishable. A flux-space permutation test on the 13-source joint sample, with construction-controlled $d_L^{\,2}$ distance bias, rejects random pairing $L_\mathrm{hX}$--$L_ν$ with $p = 6.3 \times 10^{-4}$ ($3.23\,σ$). We interpret these results as a conditional consistency check; a detection-level statement requires either an enlarged calibration set or an X-ray-weighted IceCube stacking likelihood with internal data.
[abstract 5 / 31] Wow! (score: 8) - Title: A VLBA-resolved Jet Associated with Super-Eddington Accretion in a Radio-loud Quasar at $z=3.4$Authors: Sakiko Obuchi, Ingyin Zaw, Kazuhiro Hada, Kohei Ichikawa, Joseph D. Gelfand,Comments: 9 pages, 4 figures, submitted to ApJLSubjects: astro-ph.GA astro-ph.HECreated: 2026-05-15; Updated: 2026-05-18; Datestamp: 2026-05-18
We report the detailed JET properties of eROSITA Final Equatorial Depth Survey (eFEDS) J084222.9+001000 (hereafter ID830), a radio-loud super-Eddington QUASAR at $z=3.4351$, revealed by Very Long Baseline Array (VLBA) observations at 1.6 GHz, 4.9 GHz, and 8.2 GHz. Thanks to the high spatial resolution of the VLBA, we successfully resolve a parsec-scale core-JET structure of ID830, and find a well-collimated JET extending over $\approx 745$ pc, making it the most distant and one of the very few currently known radio-loud QUASARs with a resolved JET associated with super-Eddington accretion. The physical scale and evolutionary track of ID830 differs markedly from the low-$z$ analogues, such as nearby radio-luminous high-Eddington narrow-line Seyfert 1 galaxies, suggesting that this source represents a distinct high-$z$ population compared to previously known samples, with important implications for AGN feedback in early galaxy evolution. We also find that the JET has a RELATIVISTIC speed of $v \gtrsim 0.19c$ and a modest viewing angle of $ϕ\lesssim 79^\circ$ to the line of sight, although its emission is not significantly Doppler-boosted ($δ\sim 1$). This provides the first evidence that such a RELATIVISTIC and collimated JET can be produced over several hundred parsecs in the super-Eddington phase, lasting for at least $10^{3\text{-}4}$ yr. Our results call for further theoretical and numerical studies to understand the physical processes required to sustain such large-scale collimation in super-Eddington accretion, which remains a missing piece.
[abstract 6 / 31] Wow! (score: 8) - Title: Temporal evolution of the periodic GeV signal from 4FGL J1913.2+0512 and analysis of the SS 433 / W50 lobesAuthors: Ömer Faruk Çoban, Diego F. Torres, Jian Li, Daniela Hadasch, Agnibha De Sarkar, Matthew Kerr,Comments: Submitted to MNRAS on 27 April 2026Subjects: astro-ph.HECreated: 2026-05-15; Updated: 2026-05-18; Datestamp: 2026-05-18
SS 433 is a microQUASAR whose RELATIVISTIC JETs precess every ~162 days, providing a laboratory for JET-interstellar medium interactions. We present a comprehensive analysis of 16 years of FERMI Large Area Telescope data (August 2008-September 2024) of the SS 433/W50 field, using events in the 0.3-300 GeV range and employing pulsar gating to mitigate contamination from the bright nearby pulsar PSR J1907+0602. We detect the GeV source 4FGL J1913.2+0512 (TS = 45, where TS denotes the likelihood-ratio Test Statistic) with a power-law spectrum (photon index 2.61 +- 0.08) and confirm a GeV excess at the western lobe (TS = 17). The eastern lobe of SS 433 is hinted at with lower significance. One additional GeV excess, FERMI J1909.6+0552 (TS = 20; TS = 28 over 0.1-300 GeV), located outside the SS 433 / W50 system, is revealed after gating. Exposure-corrected Lomb-Scargle periodograms and precessional phase-folded light curves show a ~162-day modulation in 4FGL J1913.2+0512. This periodicity is prominent during the first 10 years of the mission (2008-2018) but disappears thereafter, with the phase-folded flux concentrated in precessional phases 0.0-0.5. Over the full 16-year dataset, the modulation remains detectable but with reduced significance, consistent with dilution by the later non-modulated epoch. These results indicate that the efficiency and/or geometry of gamma-ray production in the SS 433 environment evolves on multi-year timescales.
[abstract 7 / 31] Yes (score: 6) - Title: GeV γ-ray emission in the low-mass star-forming region AFGL 490Authors: Li-Nuo Yang, Sheng Tang, Pak-Hin Thomas Tam,Comments: 8 pages,4 figures,4 tables. Accepted for publication in MNRASSubjects: astro-ph.HECreated: 2026-05-15; Updated: 2026-05-18; Datestamp: 2026-05-18
We report the discovery of an extended GeV γ-ray source, 4FGL J0330.7+5845e, associated with the star-forming region AFGL 490 using 17 years of FERMI-LAT data. The emission is spatially coincident with a dense molecular cloud and centered near the massive protostar AFGL 490. Its spectral energy distribution shows a distinct high-energy cutoff. Both leptonic and hadronic models can fit the γ-ray spectrum, but energetic arguments rule out stellar winds as the primary accelerator. Instead, the protostellar JET driven by AFGL 490 is identified as a plausible site for particle acceleration, and the derived timescales and maximum particle energies are consistent with theoretical predictions for such JETs.
[abstract 8 / 31] Yes (score: 5) - Title: Re-acceleration of Energetic Ions via Small-Scale Reconnection in Magnetic Fusion PlasmasAuthors: Cong Zhang, Shaodong Song, Di Luo, Kai Huang, Linge Zang, Huibo Tang, Yanchao Li, Yihang Zhao, Ao Wang, Hanqing Wang, Zhenxing Wang, Lei Han, Xuxu Zhang, Jia Li, Dong Guo, Yunfeng Liang, Minsheng Liu, Yuejiang Shi,Comments:Subjects: physics.plasm-phCreated: 2026-05-15; Updated: 2026-05-18; Datestamp: 2026-05-18
We report the first observation on the EXL-50U spherical torus that energetic particles injected by neutral beam injection (NBI) can be stably accelerated to significantly higher energies - reaching up to 2.5 times the injection energy, occurring without significant large-scale MAGNETohydrodynamic (MHD) bursts. Simulations based on EXL-50U parameters indicate that small-scale MAGNETic RECONNECTion, mediated by multiple MAGNETic islands, fails to accelerate bulk thermal ions but efficiently energizes seed fast ions. Unlike global MHD events, such small-scale RECONNECTion is ubiquitous in MAGNETic confinement devices and does not degrade core confinement. This mechanism offers a novel and potentially universal channel for auxiliary ion heating in future fusion reactors.
[abstract 9 / 31] Yes (score: 5) - Title: X-Ray Polarization from the Gamma-Ray Binary LS I +61 303Authors: Philip Kaaret, Sudip Chakraborty, Daniel Golonka, Oliver J. Roberts, Ioannis Liodakis, Andrea Gnarini, Steven R. Ehlert, Joel B. Coley,Comments: 8 pages, submitted to ApJSubjects: astro-ph.HECreated: 2026-05-15; Updated: 2026-05-18; Datestamp: 2026-05-18
The gamma-ray emitting binary stellar system LS I +61 303 was observed with the Imaging X-ray Polarimetry Explorer (IXPE) on two successive orbits over orbital phases of 0.74 to 1.05. Polarization is detected at a significance of 4.2$σ$ with an average POLARIZATION degree of $13.1\% \pm 3.0\%$ in the 2-8~keV band after background subtraction. This is the second detection of POLARIZATION of the X-ray SYNCHROTRON emission from a gamma-ray binary and, again, suggests that the MAGNETic field in the particle acceleration region has a significant ordered component. The orbital motion on the sky of LS I +61 303 is not well determined, which leads to ambiguity in interpretation of the X-ray electric vector POLARIZATION angle (EVPA) measurement. Use of orbital elements determined via radial velocity measurements combined with radio imaging of variable nebular emission, suggests an offset between the X-ray EVPA and the compact object-massive star axis on the order of ~30$^{\circ}$. Such an offset could be produced by Coriolis forces due to binary motion. Use of two different sets orbital elements determined via optical polarimetry suggest either no offset or a perpendicular orientation, but require an unexpectedly high inclination. Use of orbital elements derived from modeling of the keV/TeV light curves suggest good alignment between the X-ray EVPA and the compact object-massive star axis. Such alignment was found for the gamma-ray binary PSR B1259-63. If the same physical situation holds for LS I +61 303, that would favor the orbital elements derived from the keV/TeV light curves.
[abstract 10 / 31] Yes (score: 4) - Title: Hadronic Origin of Sub-PeV Gamma-Ray Emission from LHAASO J0621+3755Authors: Sonali Sahoo, Ankan Roy, Kritika Yadav, Reetanjali Moharana,Comments: 8 pages, 5 figures, 1 tableSubjects: astro-ph.HECreated: 2026-05-15; Updated: 2026-05-18; Datestamp: 2026-05-18
Very High Energy (VHE) gamma-rays in pulsars, and their surrounding halos, are interpreted to originate from the leptonic channel, electroMAGNETic interactions through electron inverse Compton (IC) scattering. In the hadronic scenario, TeV-PeV gamma-rays are generated from the decay of neutral pions, which are produced from COSMIC RAYs(CR) protons interacting with the ambient medium. Recent observations of sub-PeV gamma-rays from the halo of the pulsar PSR J0622+3749 by the Large High Altitude Air Shower Observatory Kilometer-Square Array (LHAASO-KM2A) provide an opportunity to investigate the underlying emission mechanisms. Previous studies have shown that the observed emission can be consistently explained within a leptonic framework by the slow diffusion of electrons. In this work, we explore an alternative explanation based on the hadronic scenario through the proton-proton ($pp$) interaction channel, incorporating the observation of VHE gamma-rays at 7 TeV by the High-Altitude Water Cherenkov detector (HAWC). To model the observed gamma-ray spectrum, ranging from $\sim 7~\mathrm{TeV}$ up to $200~\mathrm{TeV}$, the required CR proton luminosity is found to be $η_p \sim 0.14$ of the spin-down luminosity of PSR J0622+3749. This scenario assumes that protons propagate in a one-zone superdiffusive environment, characterized by a diffusion index $α= 1.05$, within an ambient of density, $1~\mathrm{cm}^{-3}$.
[abstract 11 / 31] Yes (score: 4) - Title: Supermassive Black Hole Winds in X-rays: SUBWAYS IV. Tracing Radio Emission and Unveiling the Role of WindsAuthors: E. Amenta, M. Brienza, G. Bruni, M. Brusa, R. Morganti, F. Panessa, R. D. Baldi, E. Behar, G. Lanzuisi, T. Shimwell, F. Tombesi, S. Bianchi, G. Chartas, A. Comastri, G. Cresci, B. De Marco, F. Fiore, M. Gaspari, V. E. Gianolli, R. Gilli, S. B. Kraemer, G. Kriss, Y. Krongold, F. La Franca, A. L. Longinotti, M. Mehdipour, E. Nardini, M. Perna, P. Petrucci, E. Piconcelli, G. Ponti, F. Ricci, L. Zappacosta,Comments: 17 pages, 9 figures, 6 tables accepted for publication in A&ASubjects: astro-ph.GA astro-ph.HECreated: 2026-05-15; Updated: 2026-05-18; Datestamp: 2026-05-18
Most Active Galactic Nuclei (AGN) are Radio Quiet, with radio emission that may arise from star-formation activity, AGN-driven winds, weak JETs, and coronal activity. Disentangling these mechanisms is challenging and requires detailed multi-wavelength investigation, but it is crucial for quantifying AGN feedback in galaxy evolution. We present a detailed radio investigation of 21 X-ray selected AGN in the Supermassive Black Hole Winds in X-Rays (SUBWAYS) sample (log Lbol = 44.9-46.3 erg/s, z=0.1-0.5), selected to systematically search for Ultra-Fast Outflows (UFOs). UFOs are detected in 30% of the targets, making the sample particularly well-suited for investigating the role and signatures of multi-scale outflows at different frequencies. We build the radio SED of the sources complementing our proprietary data, collected with the JVLA at 1.5 and 6 GHz, with images from LoTSS and other publicly available radio surveys between 150 and 1400 MHz. We investigate the role and occurrence of the aforementioned mechanisms, with particular interest in outflows and their possible relation with UFOs. We combined information on spectral indices, luminosities, and morphologies of the radio emission with properties derived in other wavebands, such as Star Formation Rate, X-ray luminosity, Eddington ratio or the UFO kinetic luminosity. All the sources are detected and are mostly consistent with RQ AGN. For 80% of the sources the data suggest the presence of an outflow (wind or weak JET). Interestingly, our results indicate that AGN with UFOs tend to have larger radio extension and a steep radio spectrum consistent with outflows. Moreover, the radio emission of the 6 UFO hosts is consistent with predictions from wind-driven shock models, possibly indicating a direct connection between the two phases. Alternatively, this may reflect physical conditions favouring the rise of both phenomena.
[abstract 12 / 31] Yes (score: 4) - Title: Ultra high-energy COSMIC RAYs from RELATIVISTIC outflows in accretion induced collapse of white dwarfsAuthors: Mainak Mukhopadhyay, Shunsaku Horiuchi,Comments: 9 pages, 4 figures, Supplemental Material (5 pages, 3 figures)Subjects: astro-ph.HE hep-phCreated: 2026-05-14; Updated: 2026-05-18; Datestamp: 2026-05-18
When a rapidly-rotating, highly MAGNETized white dwarf (WD) approaches the Chandrashekhar limit through mass accretion, it can undergo an accretion-induced collapse (AIC) to form a proto-neutron star or protoMAGNETar. The protoMAGNETar can drive a MAGNETically-dominated RELATIVISTIC outflow, whose low entropy can lead to efficient formation of heavy nuclei. In this work, we propose that such RELATIVISTIC outflows from AIC of WDs can contribute as sources of ultra high-energy COSMIC RAYs (UHECRs). We model the acceleration of heavy nuclei in these RELATIVISTIC outflows, and show that AICs can dominantly power the observed UHECRs, if a majority of them host RELATIVISTIC outflows. Accounting for uncertainties in the acceleration mechanisms and AIC rates, AICs can contribute $\sim$ a few $10^{43} - 10^{45}\ {\rm erg \ Mpc}^{-3} {\rm yr}^{-1}$ in UHECR energy generation rate density, assuming iron-like nuclei.
[abstract 13 / 31] Yes (score: 4) - Title: Bridging X-ray Polarization with Timing & Spectroscopic Parameters of a galactic BLACK HOLE: SWIFT J1727.8-1613Authors: Arka Chatterjee, Sujoy K. Nath, Kaushik Chatterjee, Samar Safi-Harb, Broja G. Dutta, Indranil Chattopadhyay, Sudip K. Garain, Hsiang-Kuang Chang,Comments: submitted to ApJ, comments are welcomeSubjects: astro-ph.HECreated: 2026-05-15; Updated: 2026-05-18; Datestamp: 2026-05-18
We report the discovery of a correlated energy-dependent time lag and degree of POLARIZATION for SWIFT J1727.8-1613 during its 2023 outburst. The energy-dependent time lag is measured around the type-C quasi-periodic oscillations (QPO) observed by IXPE on 2023-09-07, while the degree of POLARIZATION is obtained from energy-resolved polarimetric measurements. The Spearman correlation coefficient was found to be 0.8, with a null hypothesis probability of 4.2\%. Furthermore, the correlation value drops as the quality factor, or Q value, of the observed QPO frequencies decreases. The spectral properties of SWIFT J1727.8-1613 are analyzed using simultaneous Insight/HXMT data. Thereafter, we present model-independent theoretical arguments to show that processes other than inverse Comptonization also contributes to both the observed POLARIZATION and time lags. This correlation may therefore point to additional mechanisms contributing to the connection between the spectral, temporal, and polarimetric properties of BLACK HOLE binaries in their hard state.
[abstract 14 / 31] (score: 3) - Title: On the quenching of LRD X-ray emission by both Compton-thick gas and high accretion ratesAuthors: Albert Sneppen, Darach Watson, James H. Matthews, Stuart A. Sim,Comments: 5 pages, 3 figures, submitted. Comments are welcomeSubjects: astro-ph.GA astro-ph.HECreated: 2026-05-14; Updated: 2026-05-18; Datestamp: 2026-05-18
Little Red Dots (LRDs), candidate high-redshift supermassive BLACK HOLEs accreting in dense gas, remain undetected in X-rays. In previous work, we provided the first quantitative models that reproduce the optical and near-infrared spectra of LRDs with the Sirocco radiative transfer code, thereby constraining the properties of the surrounding gas. Here, we use those constraints to predict the X-ray attenuation produced by dense gas cocoons, and explore its dependence on Balmer-break strength, metallicity, intrinsic X-ray SED, and observed bandpass as a function of redshift. We find that the X-ray constraints are very tight, requiring both extinction by a Compton-thick gas column $N_{\rm H}\sim10^{25}\,{\rm cm}^{-2}$ with moderate metallicity ($0.05$-$0.1\,Z_\odot$) and intrinsically weak X-ray emission (bolometric to X-ray luminosity ratio, $k_{\rm bol,X}\gtrsim 30$) as observed in high accretion rate, narrow-line AGN, to make LRDs sufficiently faint to evade detection. Intrinsically bright X-ray emitters as seen in typical broad-line AGN would be detected even behind the typical modest metallicity, Compton-thick gas columns inferred from the optical spectra. Very low metallicity objects could be detected in X-rays even with low intrinsic X-ray luminosities, suggesting that LRDs are not (currently) chemically pristine.
[abstract 15 / 31] (score: 3) - Title: Polarization Analysis of Ringdown SignalsAuthors: Nicole Khusid, Will Farr, Max Isi,Comments: 22 pages, 14 figuresSubjects: gr-qc astro-ph.HECreated: 2026-05-14; Updated: 2026-05-18; Datestamp: 2026-05-18
Merging binary BLACK HOLEs exhibit a ringdown phase in which they primarily emit gravitational waves in the shape of damped sinusoids corresponding to quasi-normal modes of the Kerr remnant. In general, each mode carries four degrees of freedom encoding amplitude and phase information. When the modes are excited with equatorial reflection symmetry, as is the case for BLACK HOLE mergers with spins (anti)aligned to the orbital angular momentum, the symmetry constrains two degrees of freedom. As a result, the relationship between POLARIZATION amplitudes and phases in each mode is fixed by the viewing (inclination) angle to the equatorial plane. We use such a constrained model to fit the ringdown signals of both non-precessing and precessing systems such as GW150914 and GW190521, respectively. We show that we can measure the degree of circular POLARIZATION and handedness of ringdown signals like those of GW150914, even if only the two LIGO detectors are available; such a POLARIZATION measurement can be translated into an inferred source inclination assuming the reflection symmetry above, again using the ringdown signal alone. On the other hand, the constrained POLARIZATION model is insufficient to capture the POLARIZATION structure of signals from precessing systems, leading to biases in the inferred mode frequencies and amplitudes. We explore the magnitude of this effect by fitting GW190521-like injections with the restricted model, finding weaker predictive accuracy relative to the arbitrary-POLARIZATION model and potentially significant systematic biases. As our detectors continue to improve, using the correct POLARIZATION model is increasingly important to avoid biased ringdown measurements.
[abstract 16 / 31] (score: 3) - Title: The Millimeter/X-ray Relation in Rapidly Accreting Supermassive Black Holes at z <0.16Authors: Sophie M. Venselaar, Claudio Ricci, Santiago Del Palacio, Kriti K. Gupta, Chin-Shin Chang, Roberto Serafinelli, Macon A. Magno, Richard Mushotzky, Elena Shablovinskaya, Taiki Kawamuro, Ezequiel Treister, Jacob S. Elford, Susanne Aalto, George C. Privon, Michael J. Koss,Comments: 25 pages, 11 figuresSubjects: astro-ph.HE astro-ph.GACreated: 2026-05-14; Updated: 2026-05-18; Datestamp: 2026-05-18
A tight correlation between nuclear millimeter (mm) and X-ray emission has recently been found in nearby ($z < 0.01$) and low-Eddington ratio ($\rm λ_{Edd} < 0.1$) radio-quiet (RQ) Active Galactic Nuclei (AGN), suggesting a common origin in the hot X-ray corona. We test this relation in nine more distant RQ AGN ($z \sim 0.06-0.16$) with higher bolometric luminosities ($\log(L_{\rm bol}/\mathrm{erg\,s^{-1}})=45.3-46.3$), Eddington ratios ($\rm λ_{Edd} = 0.19-0.85$), and X-ray bolometric corrections ($κ_{2-10}=29-194$), selected from the Burst Alert Telescope (BAT) survey. We obtained quasi-simultaneous observations with SWIFT at 2-10 keV and the Atacama Large Millimeter/submillimeter Array (ALMA) at 100 GHz and with high angular resolution ($<0.14$"). We find that these high-luminosity AGN lie above the mm/X-ray correlation defined by lower-luminosity sources. A joint fit to both samples yields a second-degree polynomial with an intrinsic scatter of 0.32 dex. Furthermore, the mm emission correlates linearly with both the UV disk luminosity and $L_{\rm bol}$, with intrinsic scatters of 0.45 and 0.35 dex, respectively. We propose that the deviation from the linear mm/X-ray relation arises from a two-component coronal electron population: thermal electrons that produce X-rays, but become less efficient at higher luminosities, and non-thermal electrons that produce mm emission and remain tied to $L_{\rm bol}$. Additional mm emission from outflow-driven shocks may also contribute, though SED modeling and spectral index studies favor a coronal origin.
[abstract 17 / 31] (score: 3) - Title: Delayed current sheet formation due to an external field in pulsed-power-driven RECONNECTion experimentsAuthors: T. W. O. Varnish, G. V. Dowhan, M. Chen, D. M. Johnson, N. M. Jordan, J. Lee, A. P. Shah, R. Shapovalov, B. J. Sporer, R. D. McBride, J. D. Hare,Comments: 11 pages, 7 figures. Submitted to Physics of PlasmasSubjects: physics.plasm-phCreated: 2026-05-14; Updated: 2026-05-18; Datestamp: 2026-05-18
We present results from pulsed-power-driven MAGNETic RECONNECTion experiments, in which we drove two exploding wire arrays in parallel to produce colliding plasma flows with anti-parallel MAGNETic fields of 1.2$\pm$0.2 T. The experimental volume was surrounded by a Helmholtz coil pair capable of externally applying a field of up to 2 T, parallel to the RECONNECTing electric field. We diagnosed these experiments using LASER interferometric imaging in the direction of the anti-parallel MAGNETic fields, gated extreme ultraviolet pinhole imaging, and in situ inductive probes. For zero and weak (0.5 T) external fields, we reproduce previous observations in which a dense RECONNECTion layer forms between the two wire arrays. However, when we apply a strong external field (2 T), we observe a void between the arrays rather than a dense layer, and we hypothesise that the external field is frozen out of the plasma and provides a back-pressure which decelerates the flows. Our experimental results are compared with three-dimensional MAGNETohydrodynamic simulations of the experiment, which qualitatively support this hypothesis. These simulations allow us to study the pressure balance and dynamics of the current sheet aspect ratio, demonstrating the delayed formation of the RECONNECTion layer due to the external field.
[abstract 18 / 31] (score: 3) - Title: Searching for Spider-Like Pulsars from TESS Ellipsoidal Lightcurves with X-ray counterpartsAuthors: Xiaoqing Liang, Partha Sarathi Pal, P. H. Thomas Tam, Rishank Diwan, Wen-Jun Huang,Comments: 18 pages, 18 figures, 2 tablesSubjects: astro-ph.HE astro-ph.SRCreated: 2026-05-15; Updated: 2026-05-18; Datestamp: 2026-05-18
We present a search for new spider pulsar candidates through multi-wavelength cross-matching, including $γ$-ray, X-ray, and optical data. A search for sinusoidal-like optical modulations in TESS data of 183 eROSITA X-ray sources coincident with unassociated FERMI-LAT gamma-ray sources led to the identification of four promising spider pulsar candidates. We found optical variability periods ranging from 5 to 13 hours. All candidates display smooth sinusoidal-like phase light curves, similar to what can be expected from ellipsoidal variation; one shows double-peaked profiles indicative of harmonics. The absence of sharp minima, which are often found in black widow systems due to irradiation, together with their optical magnitudes of about G~14, suggests these sources are more likely redback-type binaries. One of the FERMI-LAT counterparts is included in a machine-learning catalog of unassociated gamma-ray sources, with relatively high pulsar probabilities. We also identify potential Gaia counterparts for several sources and estimate their distances and luminosities where parallax measurements are available. Future observations, including further spectroscopic and multi-wavelength studies, are needed to fully characterize these systems.
[abstract 19 / 31] (score: 3) - Title: Nucleosynthesis in the fast ejecta of a neutron star mergerAuthors: Lukas Schnabel, Stephan Rosswog, Friedrich-Karl Thielemann, Moritz Reichert,Comments: Submitted to MNRAS, 15 pages, 14 figuresSubjects: astro-ph.HECreated: 2026-05-15; Updated: 2026-05-18; Datestamp: 2026-05-18
Neutron star mergers are today considered a major production site for rapid neutron capture elements. While the bulk of the matter escapes at fast, but non-RELATIVISTIC velocities (${\sim} 0.2\,c$), a small amount of the dynamically ejected mass reaches mildly RELATIVISTIC velocities (${\gtrsim}0.6\,c$). It has been suggested earlier, that in such ejecta parts neutrons may avoid being captured and that their decay could power an early blue precursor to the main kilonova event. Here we study in detail the nucleosynthesis in such fast ejecta with nuclear network calculations along both parametrized and numerical relativity trajectories. We find that the nucleosynthesis can be divided into three channels, in one of which a substantial amount of free neutrons survives when the main r-process has frozen out. We provide a (semi-)analytical model for surviving free neutrons which agrees very well with the network calculations. If the mass fraction of the free neutrons exceeds ${\sim} 0.05$, their $β^-$-decay dominates the nuclear heating rate between ${\sim} 100$ and ${\sim} 10^4$ seconds. This dominance leads to a pronounced kilonova precursor that should for plausible ejecta parameters be visible for ULTRASAT out to ${\sim}200\,\rm Mpc$. Since at low electron fractions free neutrons can survive even for moderate velocities, mergers with large tidal ejecta, such as asymmetric neutron star mergers or favorable neutron star BLACK HOLE mergers, may produce particularly bright blue precursors to their subsequent kilonovae.
[abstract 20 / 31] (score: 3) - Title: Kinetic Simulations of Laser-Driven Compression and Heating of Magnetised Cryogenic Hydrogen Targets using PIConGPUAuthors: Filip Optołowicz, Klaus Steiniger, David Blaschke, Michael Bussmann, Brian Marre,Comments: 24 pages, 17 figures. Submitted to ParticlesSubjects: physics.plasm-ph physics.comp-phCreated: 2026-05-15; Updated: 2026-05-18; Datestamp: 2026-05-18
We present fully kinetic two-dimensional, three-velocity-component (2D3V) PIConGPU simulations of a three-beam direct-drive interaction with a 15 $μ$m solid-density cryogenic hydrogen cylinder, establishing a predictive numerical baseline for the operational DRACO ($τ=30$ fs) and upcoming PENELOPE ($τ=150$ fs) LASER facilities at HZDR. The simulations resolve charge-separation fields on the order of 3 TV/m and reveal a robust kinematic bifurcation of the accelerated population into a fast (1-5 MeV) ion beam and a slower bulk (1-100 keV) flow. We demonstrate analytically and numerically that the charge-separation front ($v_{hb}$) is an intrinsically non-quasi-neutral electrostatic double layer that lies outside the closure assumptions of radiation-hydrodynamic models. A simple $2v_{hb}$ reflection scaling derived directly from the front trajectory tracks the centroid of the constant-energy fast-ion band under the impulsive 30 fs driver and the time-varying upper edge of the swept fast-ion band under the sustained 150 fs driver, across both intensities ($a_{0}=12.7$ and 22.0), establishing this non-thermal mechanism as the dominant acceleration pathway. We then scan an external axial MAGNETic field from 0 T to 10 kT. Laboratory-achievable 20 T fields leave all macroscopic observables unchanged; fields at the kT scale progressively MAGNETise the MeV hot-electron population, quench the LASER-driven charge-separation mechanism, suppress the fast-ion band, and more than double the net-inward compression time of the short-pulse driver-while extending the outer target envelope. A geometric equivalence argument maps these kT-scale results onto larger-diameter cryogenic hydrogen JETs.
[abstract 21 / 31] (score: 2) - Title: The First Upper Bound on the Non-Stationary Gravitational Wave Background and its Implication on the High Redshift Binary Black Hole Merger RateAuthors: Mohit Raj Sah, Suvodip Mukherjee,Comments: 14 pages, 10 figures. Accepted for publication in PRDSubjects: astro-ph.HE astro-ph.CO gr-qcCreated: 2026-05-15; Updated: 2026-05-18; Datestamp: 2026-05-18
The high redshift merger rate and mass distribution of BLACK HOLE binaries provide a direct probe to distinguish astrophysical BLACK HOLEs (ABHs) and primordial BLACK HOLEs (PBHs), which can be studied using the Stochastic Gravitational-Wave Background (SGWB). The conventional analyses solely based on the power spectrum are limited in constraining the properties of the underlying source population under the assumption of a non-sporadic Gaussian distribution. However, recent studies have shown that SGWB is expected to be sporadic and non-Gaussian in nature, which gives rise to non-zero \textit{spectral correlation} that depends on the high redshift merger rate and mass distribution of the compact objects. In this work, we present the first spectral covariance analysis of the SGWB using data from the LIGO--Virgo--KAGRA collaboration during the third and the first part of the fourth observing runs. Our analysis indicates that the current spectral correlation is consistent with non-stationary noise, yielding no detection and providing only upper bounds over the frequency range of 20 Hz to 100 Hz. This upper bound on the spectral correlation translates into a mass-distribution-dependent upper bound on the merger rate of PBHs. This provides a stringent upper bound on the PBH merger rate at high redshift and hence puts constraints on the PBH formation scenarios. In the future, detection of this signal will provide a new avenue to probe the high-redshift BLACK HOLE population using gravitational waves.
[abstract 22 / 31] (score: 2) - Title: A case for Case A: detailed look at binary BLACK HOLE formation through stable mass transferAuthors: Max M. Briel, Tassos Fragos, Monica Gallegos-Garcia, Anarya Ray, Michael Zevin, Abhishek Chattaraj, Jeff J. Andrews, Vicky Kalogera, Seth Gossage, Philipp M. Srivastava, Elizabeth Teng,Comments: Accepted in A&ASubjects: astro-ph.HECreated: 2026-05-15; Updated: 2026-05-18; Datestamp: 2026-05-18
In isolated binary evolution, binary BLACK HOLE (BBH) mergers are generally formed through stable mass transfer (SMT) or common envelope evolution. In recent years, the SMT channel has received significant attention due to detailed binary models showing increased mass transfer stability compared to previous studies. In this work, we perform a full zero-age-main-sequence to compact object merger analysis using detailed binary models at eight metallicities between $10^{-4}Z_\odot$ and $2Z_\odot$ to self-consistently model the population properties of BBH mergers in the SMT channel, determined their progenitor initial conditional, and investigate the binary physics governing their formation and metallicity dependence. We use the population synthesis code POSYDON to determine the population of BBH mergers from SMT. Using its extended grids of MESA binary models, we determine the essential physics in the formation of BBH mergers. SMT produces BBH mergers predominantly from systems with $P_{ZAMS}\leq10$ days. In these systems, both the initial mass transfer between two stars and the subsequent interaction between the remaining star and the first-born BH take place while the respective donor star is on the main-sequence (Case A). We find a limited contribution from wider Case B/C systems. Without a natal kick, the SMT channel does not produce BBH mergers above $Z>0.2Z_\odot$ due to orbital widening from stellar wind mass loss. The primary BH mass distribution shows a strong dependence on metallicity, while the mass ratio prefers unity independent of metallicity due to mass ratio reversal. Additionally, the $χ_{eff}$ distributions contain peaks at $χ_{eff}=0$ and ~0.15 of which the former disappears at high metallicities. A mass-scaled natal kick leave this sub-population unchanged but introduce a low-mass, unequal mass ratio sub-population that merges due to their high eccentricity.
[abstract 23 / 31] (score: 2) - Title: The Structure and Evolution of LRDs: Insights from JWST NIRSpec Medium and High Resolution Spectroscopy at $z\sim4$Authors: Yuxuan Pang, Xin Wang, Cheng Cheng, Shengzhe Wang, Hang Zhou, Qianqiao Zhou, Xue-Bing Wu, Karl Glazebrook,Comments: 20 pages, 8 figures, accepted by ApJSubjects: astro-ph.GACreated: 2026-05-15; Updated: 2026-05-18; Datestamp: 2026-05-18
We present an analysis of medium/high-resolution JWST/NIRSpec spectra for 11 LRDs at $z \sim 4$. By decomposing the broad and narrow components of the Balmer emission lines, we investigate the connection between line emission and UV/optical continua for the LRD population. We find that the broad H$α$ luminosity strongly correlates with the optical continuum (but not with the UV), indicating a common AGN origin for both. In contrast, the [O III] line strength is correlated with the UV continuum rather than the optical. Using the width and luminosity of the broad H$α$ line, we estimate central BLACK HOLE masses of $10^6-10^8 M_{\odot}$ accreting at high Eddington ratios, consistent with an early ($λ_{\rm Edd} \sim 0.6$), rapid-growth phase of AGN evolution. Assuming a constant mass accretion rate in the framework of slim-disk models, we infer growth timescales of $\sim 10^5-10^7\rm yr$, and suggest LRDs may evolve into narrow-line Seyfert 1 galaxies. Upper limits from our spectra indicate that LRDs exhibit intrinsically weak optical Fe II emission compared to typical AGN. To simultaneously account for the inferred broad-line region size and observed luminosity, we propose a "Clumpy Envelope" model in which the optical emission arises from an extended, clumpy gas with a characteristic radius of tens of light-days. The diversity in observed optical continuum shapes can be explained by radial temperature gradients and self-absorption effects within this structure. Our results demonstrate the power of JWST high-resolution spectroscopy in probing the central engines and physical nature of the LRD population.
[abstract 24 / 31] (score: 2) - Title: A Spatially Resolved HI Survey of Seyfert Galaxies: the Role of AGN Feedback in Shaping Atomic Gas ReservoirsAuthors: Ruitian Li, Xin Wang, Daizhong Liu, Hui Shi, Yuxuan Pang, Pengfei Ren, Shengzhe Wang, Ming Zhu, Mengting Ju, Xiao-Lei Meng, Xinwen Shu, Ningyu Tang, Jing Wang, Chuan-Peng Zhang, Hong-Xin Zhang, Le Zhang, Zheng Zheng, Fujia Li, Chen Xu, Sijia Li, Yiming Yang, Hang Zhou,Comments: 16 pages, 8 figures, 4 tables, Accepted for publication in ApJSSubjects: astro-ph.GACreated: 2026-05-15; Updated: 2026-05-18; Datestamp: 2026-05-18
Active galactic nucleus (AGN) feedback is a key ingredient in galaxy evolution, yet its impact on the cold atomic gas reservoir -- the neutral hydrogen (HI) phase -- remains poorly constrained. We present the most extensive spatially resolved HI 21-cm survey of Seyfert AGN hosts to date, based on observations with the Giant Metrewave Radio Telescope (GMRT). Our high-resolution HI maps of eight Seyfert galaxies reveal detailed kinematics and surface density distributions of their atomic gas disks. We find that AGN-host galaxies exhibit a slightly shallower HI mass-size relation than the canonical relation or the SIMBA simulation predictions; however, the measured slope remains consistent with the canonical value within $2σ$ uncertainties. This result suggests that AGN feedback does not significantly disrupt the global extent or large-scale structure of atomic gas reservoirs. To investigate the internal HI kinematics in greater detail, we perform a 3D kinematic forward modeling of the HI disk in UGC 4503. Our analysis reveals an elevated intrinsic velocity dispersion of $σ= 14.9^{+6.1}_{-3.8}$ km/s and a reduced level of rotational support, with $V/σ= 14.28_{-4.17}^{+4.97}$, compared to large-sample star-forming spirals. These kinematic signatures, together with localized residuals in the velocity field, indicate that AGN-driven outflows or JETs may inject or indirectly affect the turbulence in the atomic gas disk, potentially regulating the cold gas reservoir. Future GMRT observations, combined with optical integral-field spectroscopy from MaNGA, will enable quantitative constraints on the role of AGN feedback in regulating STAR FORMATION efficiency across a larger and more representative galaxy sample.
[abstract 25 / 31] (score: 2) - Title: Dymnikova Black Holes in Unimodular Gravity: Maxwell Sources and Vacuum ContributionsAuthors: G. Alencar, V. H. U. Borralho,Comments:Subjects: gr-qcCreated: 2026-05-14; Updated: 2026-05-18; Datestamp: 2026-05-18
In this work, we investigate the Dymnikova regular BLACK HOLE within the framework of unimodular gravity, emphasizing the role of the effective vacuum sector in the regularization of the geometry. By allowing a controlled violation of the covariant conservation of the energy--momentum tensor, the cosmological contribution emerges dynamically as a radial-dependent function, $Λ=Λ(r)$. We first reinterpret the Dymnikova spacetime as a charged configuration supported by nonlinear electrodynamics and derive the corresponding electric and MAGNETic sources. Subsequently, we demonstrate that the same geometry can be consistently generated by standard Maxwell electrodynamics in unimodular gravity. In this construction, the resulting electric field is everywhere regular and corresponds to a localized charge distribution with vanishing asymptotic charge, indicating that the spacetime does not behave as an asymptotically charged object.
[abstract 26 / 31] (score: 2) - Title: Eccentric Stellar-mass Binary Black Holes: Population, Detectability, and Waveform Analysis in the LISA and LIGO EraAuthors: Zeyuan Xuan, Smadar Naoz, Kyle Kremer, Michael L. Katz, Bence Kocsis, Erez Michaely,Comments: 26 pages, 14 figures. Comments are welcomeSubjects: astro-ph.HE gr-qcCreated: 2026-05-14; Updated: 2026-05-18; Datestamp: 2026-05-18
Eccentric binary BLACK HOLEs (BBHs) formed through dynamical interactions can significantly contribute to gravitational wave (GW) detections. In this work, we present a simulated catalog of dynamically-formed, stellar-mass BBHs in the local universe, incorporating contributions from the Galactic field (flyby interactions), Galactic nucleus (eccentric Kozai-Lidov evolution), and globular clusters (N-body interactions). Our results predict a wide, highly eccentric BBH population in the Milky Way (MW), with source counts of $\sim 36, 13, 4.7, 2.3, 1.0$ (for $\mathrm{SNR} > 1, 3, 8, 20, 50$, respectively) during a 10-yr LISA observation. Extending this model to cosmological populations, we show that different dynamical channels can produce distinct eccentricity distributions in the LVK band and can contribute hundreds of additional low-SNR mHz sources. Specifically, our model yields a merger rate of $Γ\sim 9 \mathrm{Gpc}^{-3}\mathrm{yr}^{-1}$ and $\sim 490$ extragalactic mHz BBHs with $\mathrm{SNR} > 1$. However, due to the lower mass and weaker GW signals of stellar-mass BBHs, this number declines sharply at higher detection thresholds (e.g., $\sim 1$ for $\mathrm{SNR} > 8$). We further highlight the impact of eccentric BBH signals on the LISA global fit, showing that their individual harmonics can be independently detected in the Milky Way, and may mimic circular binaries with systematically biased chirp masses. Lastly, we show that post-Newtonian waveforms converge reliably for eccentric BBHs with masses of $\lesssim 10^3 M_\odot$ in the mHz band. Overall, eccentric BBHs represent a prevalent and promising target for future space-based GW observatories. The simulated catalog and the LISA Eccentricity Astrophysics Package (LEAP) developed in this work are publicly available at https://github.com/zeyuanxuan/lisa-leap/.
[abstract 27 / 31] (score: 2) - Title: Population synthesis of Galactic middle-aged pulsar wind nebulae I. Detection prospects for current and future instrumentsAuthors: A. De Sarkar, D. F. Torres, B. Olmi, N. Bucciantini, D. M. -A. Meyer,Comments: 19 pages, 10 figures, 3 tables; accepted for publication in Astronomy & Astrophysics (A&A)Subjects: astro-ph.HECreated: 2026-05-14; Updated: 2026-05-18; Datestamp: 2026-05-18
Pulsar wind nebulae (PWNe) constitute the largest population of Galactic very-high-energy (VHE; $E > 100$ GeV) $γ$-ray sources and are key laboratories for studying particle acceleration and pulsar--SUPERNOVA remnant (SNR) interactions. However, realistic population-level predictions have so far lacked any detailed treatment of the reverberation phase, when the nebula is compressed by the SNR reverse shock, significantly altering its dynamics and radiative spectrum. We employ the hybrid \texttt{TIDE+L} framework, which combines a thin-shell dynamical model with a Lagrangian treatment of the SNR structure during reverberation, allowing self-consistent evolution of thousands of PWNe across all stages up to $10^5$ yr. Each source is evolved under distributions of pulsar spin-down, SNR, and environmental properties, and the resulting $γ$-ray fluxes are used to estimate the detectability by current and next-generation $γ$-ray observatories while accounting for their sensitivity and sky coverage. The model predicts that the upcoming Cherenkov Telescope Array Observatory (CTAO) will detect an order of magnitude more PWNe than those firmly detected in the TeV range, confirming its dominant contribution to the forthcoming TeV population census. Our results demonstrate that realistic modeling of reverberation is important for predicting the Galactic TeV PWNe population.
[abstract 28 / 31] (score: 2) - Title: Disformal Kerr Imprints on BHL Accretion: Shock Morphology, PSD Signatures, and Observational QPO CounterpartsAuthors: Orhan Donmez, M. Yousaf, Imtiaz Khan, G. Mustafa,Comments: 15 pages, 9 figures, 2 TablesSubjects: astro-ph.HE gr-qcCreated: 2026-05-15; Updated: 2026-05-18; Datestamp: 2026-05-18
We reveal the effect of the spacetime parameters on the accretion morphology formed through the BHL mechanism around a slowly rotating disformal Kerr BLACK HOLE. Thus, we investigate the measurable signatures of these parameters on the hydrodynamical morphology and the timing behavior of the accreting flow. It is shown that even weak disformal deviations from the Kerr solution modify the shock-cone structure, enhance the density in the post-shock region, and produce coherent oscillations in the accretion rate. The Kerr model produces coherent peaks at 42.99 Hz and 68.13 Hz, and these frequencies are consistent with the high-frequency QPOs observed from the source GRS 1915+105. In the models where the deviations from the Kerr solution are weak, low-frequency QPOs are produced and found to be coherent. These frequencies also fall within the frequency range observed in Galactic black-hole binaries. On the other hand, the models with large deviations from Kerr can be used to explain observational results that are more irregular, broad-band, and contain multiple peaks. In addition, by using inverse-mass scaling in this work, the numerically calculated frequencies are also compared with observations of intermediate-mass and supermassive BLACK HOLEs. In particular, the disformal black-hole models are found to be consistent with the observational results obtained from the sources M82 X-1, NGC 5408 X-1, and RE J1034+396. This comparison also allows the possible black-hole mass range of observed sources to be inferred from the relation between simulated and observed frequencies. This makes BHL accretion in disformal Kerr geometry a powerful framework for connecting modified-gravity black-hole spacetimes with observable QPO phenomenology.
[abstract 29 / 31] (score: 2) - Title: Constraints on primordial BLACK HOLEs from the first part of LIGO-Virgo-KAGRA fourth observing runAuthors: M. Andrés-Carcasona, A. J. Iovino, E. Vallejo-Pagès, V. Vaskonen, H. Veermäe, M. Martínez, Ll. M. Mir,Comments:Subjects: astro-ph.CO astro-ph.HE gr-qcCreated: 2026-05-15; Updated: 2026-05-18; Datestamp: 2026-05-18
We analyze PBH populations using state-of-the-art modeling of PBH binaries, deriving the strongest bounds on PBH abundance in the $0.6-100 M_\odot$ range from LIGO-Virgo-KAGRA O4a data and demonstrating sensitivity in the $10^{-4}-10^4 M_\odot$ range. The constraints are dominated by resolvable PBH mergers, while the associated gravitational wave background provides complementary but weaker limits. Allowing PBHs to account for a subset of the cataloged events slightly relaxes these bounds. However, a joint fit with astrophysical BLACK HOLEs shows no compelling evidence for a PBH contribution.
[abstract 30 / 31] (score: 2) - Title: Mechanisms for MAGNETic braking boost and disruption: the role of irradiation-driven winds and convective turnover time spike in cataclysmic variablesAuthors: Vladislav Dodon, Xiang-Dong Li, Xiao-jie Xu, Ilkham Galiullin, Askar Sibgatullin,Comments: 15 pages, 10 figures, 1 table. Accepted for publication in A&ASubjects: astro-ph.SR astro-ph.HECreated: 2026-05-15; Updated: 2026-05-18; Datestamp: 2026-05-18
The saturated, boosted, and disrupted MAGNETic braking (SBD MB) model is an empirical prescription that has recently gained support from close-binary observations. Different boosting ($K$) and disruption ($η$) parameters appear necessary for different systems, but their physical origins remain uncertain. We aim to identify the mechanisms that boost MAGNETic braking (MB) and cause its disruption at the fully convective boundary in cataclysmic variables (CVs). We modelled CV evolution with MESA and compared the results with observed CV properties. We computed the convective turnover time ($τ_c$) directly from the donor's structure rather than adopting empirical relations. We also included irradiation from the accreting white dwarf, which heats the donor's outer layers and can drive additional winds that enhance MB. The structure-based $τ_c$ calculation reveals a pronounced spike as the donor approaches full convection, which drives the disruption parameter $η$ and initiates the period gap in CVs. The outcome of irradiation is sensitive to the accretion, irradiation, and wind efficiencies, all of which are poorly constrained from observations. Despite these uncertainties, plausible parameter choices allow irradiation-driven winds to provide the required boost $K$ during accreting phases. We refer to the combined prescription as the i$τ$SBD MB model and find that it yields evolutionary tracks broadly consistent with the main CV properties. Our i$τ$SBD MB framework offers a physically motivated interpretation of the empirical boost and disruption factors in SBD MB for CV evolution. We suggest that the convective turnover time spike at the fully convective boundary may drive MB disruption for fast-rotating stars in the saturated regime, while irradiation-driven winds may be the dominant mechanism boosting MB in accreting binaries and other strongly irradiated close systems.
[abstract 31 / 31] (score: 2) - Title: Dynamic Plasma Shape Control with Arbitrary Sensor SubsetsAuthors: D. Sorokin, M. Stokolesov, A. Granovskiy, I. Prokofyev, E. Adishchev, M. Nurgaliev, E. Khayrutdinov, G. Subbotin, R. Clark, D. Orlov,Comments:Subjects: cs.RO cs.SY eess.SY physics.plasm-phCreated: 2026-05-15; Updated: 2026-05-18; Datestamp: 2026-05-18
Plasma shape control in tokamaks requires a real-time controller that tracks dynamically changing shape targets while tolerating diagnostic failures. Classical approaches decompose the problem into equilibrium reconstruction followed by a linear controller, and assume a fixed, fully operational sensor set. We present a reinforcement learning agent that addresses both limitations simultaneously. The agent is trained in NSFsim, a high-fidelity tokamak simulator configured for DIII-D, on a curated dataset of 120 experimental plasma shapes. The shape targets are resampled as random step changes every 0.25 s, exposing the agent to diverse transitions across the full shape envelope. At test time the agent zero-shot tracks dynamic shape sequences; on a held-out static configuration in simulation it achieves a mean shape error of 2.01 cm, and dynamic trajectory following is demonstrated qualitatively in simulation and on the physical device. Diagnostic dropout randomly masks 30% of MAGNETic sensors per episode, yielding a single policy robust to arbitrary sensor subsets without backup controllers or mode-switching logic. An asymmetric actor-critic architecture with privileged equilibrium information improves value estimation under partial observability; an auxiliary shape reconstruction head on the actor enables end-to-end shape reconstruction from raw diagnostics and serves as an interpretability tool for policy analysis. The policy transfers to experimental DIII-D shots, where it directly commands the coil actuators on two dynamic shape maneuvers, and to the independent GSevolve simulator.
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