Current date: 2026-04-24
Setting default datestamp limit: 0
Datestamp limit: 2026-04-24 (0 days ago)
Created/updated limit: 2026-04-17 (7 days ago)
Found keywords_cs.datFound keywords_cis.dat
Suggested sets: physics, physics:astro-ph, physics:gr-qc, physics:physics
Setting default set: physics
OAI-PMH request: http://export.arxiv.org/oai2?verb=ListRecords&from=2026-04-24&until=2026-04-24&set=physics&metadataPrefix=arXiv
Scoring abstracts
Number of records retrieved: 620
Keyword score statistics
score 12 -- 1 abstracts
score 6 -- 2 abstracts
score 5 -- 1 abstracts
score 4 -- 4 abstracts
score 3 -- 10 abstracts
score 2 -- 23 abstracts
in total -- 41 abstracts
Articles that appeared on 2026-04-24
-
[abstract 1 / 41] Wow! (score: 12)
- Title: Relationship between the $γ-$ray variability and the pc-scale JET in the BLAZAR 3C 454.3Authors: Eva Palafox, Víctor Manuel Patiño-Álvarez, Vahram Chavushyan, Andrei Lobanov, Sergio A. Dzib, J. Anton Zensus,Comments: A&A accepted, 9 pages, 6 figuresSubjects: astro-ph.HE astro-ph.GACreated: 2026-04-23; Updated: 2026-04-24; Datestamp: 2026-04-24
3C 454.3 is a flat spectrum radio QUASAR (FSRQ) known for its high variability across the electroMAGNETic spectrum, showing structural and flux variability in its pc-scale JET, and correlated variability among frequency bands. This study aims to identify the structure, dynamics, and radiative processes common to the innermost regions of the BLAZAR 3C 454.3. We investigate whether any JET component can be associated with $γ-$ray emission and variability. We analyze the relationship between the variable $γ-$ray emission and pc-scale JET properties in 3C 454.3 by combining $γ-$ray data spanning twelve years with contemporaneous VLBA multi-epoch images at 15 and 43 GHz. Spearman rank correlation tests are conducted to determine if the flux variability of any JET component is associated with $γ-$ray variability. Core emission at 43 and 15 GHz strongly correlates with $γ-$ray emission. The 43 GHz core (Q0) contributes around 37$\%$ of the observed $γ-$ray variability, while the 15 GHz core (K0) accounts for 30$\%$. A quasi-stationary component at 43 GHz, at a projected distance of 4.6 pc, correlates with the $γ-$ray flux, accounting for 20$\%$ of its emission between 2016 and 2021. We found a mobile component (Q3 between 2010.18 and 2011.16) at 43 GHz with a projected distance between 0.8 and 2.3 pc and apparent velocity of $β_{app} = 9.9 \pm 1.1$ c, accounting for approximately 28% of the $γ-$ray emission. The observed simultaneous variability in emission regions beyond the central parsec strongly suggests SYNCHROTRON self-Compton (SSC) as the primary mechanism for $γ-$ray production in these regions. Our findings demonstrate the existence of multiple $γ-$ray emission regions within the BLAZAR JET but also suggest that some of these regions are non-stationary over time.
[abstract 2 / 41] Yes (score: 6) - Title: Detections of nearly bias-free core shifts with 5-30 $μ$as precisions at 8-43 GHz in BL LacertaeAuthors: Niu Liu, Jun Yang, Xiaopeng Cheng, Ai-Ling Zeng, Wen Chen, Xiao-Long Yang, Xiaoyu Hong, Xia-Xuan Zhang, Jia-Cheng Liu, Zi Zhu,Comments: 12 pages, 6 figures, accepted for publication in ApJSubjects: astro-ph.HE astro-ph.GACreated: 2026-04-23; Updated: 2026-04-24; Datestamp: 2026-04-24
When a radio JET is partially optically thick in the launching region, its apparent compact core may display frequency-dependent positional shifts. High-precision astrometric measurements of core shifts enable astronomers to pinpoint the JET's origin and place tight constraints on the MAGNETic field. BL Lacertae, the archetypal BL Lac object, hosts a highly variable and well-collimated JET. To independently constrain its innermost core shifts, we conducted very long baseline interferometric (VLBI) observations at 8.4, 12.4, 15.2, 23.6, and 43.2 GHz. By exploiting a nearby (13.3 arcmin) steep-spectrum calibrator (NVSS J220340+420839) through inverse phase-referencing VLBI astrometry, we detect nearly unbiased two-dimensional core shift measurements with state-of-the-art precisions of 5-30 $μ$as, which are significant at $>3σ$ confidence. The core shift between 8.4 and 43.2 GHz reaches 250 $μ$as. The apparent core shifts scale with frequency as $ν^{-1/k_r}$, implying the existence of an optically thick region in the upstream of JET. The derived core-shift index, $k_r\!=\!1.18^{+0.59}_{-0.34}$, is consistent, within uncertainties, with the canonical $k_r\!=\!1$ expected under energy equipartition between the JET particle and MAGNETic field energy densities, while allowing for modest deviations given that BL Lacertae was captured in a flaring state.
[abstract 3 / 41] Yes (score: 6) - Title: A Synchronized Spin Model for Black-Hole Accretion SystemsAuthors: Masahiro Morikawa, Akika Nakamichi,Comments: 37 pages, 11 figuresSubjects: astro-ph.HE nlin.AOCreated: 2026-04-23; Updated: 2026-04-24; Datestamp: 2026-04-24
Black-hole accretion systems exhibit a characteristic coexistence of activities: broad-band X-ray variability, hot coronae, wide-angle winds, and both steady and discrete JETs. This coexistence suggests a persistently time-dependent MAGNETic background in which noisy fluctuations and explosive release are both essential. In this paper, we connect them all to intermittent MAGNETic RECONNECTion and propose a Synchronized Spin Model (SSM) in which multiple local dynamos in a rotating accretion flow are represented as interacting macro-spins. Their synchronization, partial synchronization, excursion, and reversal define a compact set of collective variables that organize both timing statistics and large-scale morphology. In this picture, multiscale MAGNETic RECONNECTion sustains coronal heating, flares, intermittent outflows, and discrete JET activity, while the same synchronization dynamics produce amplitude modulation and demodulation, providing a route to $1/f$-like variability, rms--flux/Taylor-like scaling, and approximately log-normal statistics of the demodulated envelope. We further argue that, although the continuous flux distribution in black-hole systems is more naturally discussed in multiplicative or log-normal terms, broader event-catalog statistics remain useful for describing suitably defined burst hierarchies, particularly by analogy with solar and stellar flare systems. The hard/soft cycle of X-ray binaries is then interpreted as motion through MAGNETic state space.
[abstract 4 / 41] Yes (score: 5) - Title: Turbulence Mode Decomposition and Anisotropy in Magnetically Dominated Collisionless PlasmasAuthors: Samuel T. Sebastian, Siyao Xu, Yue Hu, Luca Comisso, Saikat Das, Joonas Nättilä,Comments: 9 pages, 7 figures, accepted for publication in The Astrophysical JournalSubjects: physics.plasm-ph astro-ph.HECreated: 2026-04-22; Updated: 2026-04-24; Datestamp: 2026-04-24
We use the 3D fully kinetic simulation to study different turbulence modes and turbulence anisotropy of RELATIVISTIC turbulence in MAGNETically dominated collisionless plasmas. We extend the method developed by Cho & Lazarian (2002) for decomposing non-RELATIVISTIC MAGNETohydrodynamic (MHD) turbulence into Alfvén, fast, and slow modes to the regime of collisionless plasmas. We find that Alfvén and slow modes are anisotropic, following the Goldreich & Sridhar (1995) scaling, while fast modes are isotropic. We observe a larger kinetic energy fraction of fast modes compared to that in the non-RELATIVISTIC MHD turbulence, suggesting a stronger coupling of Alfvén and fast modes in RELATIVISTIC MAGNETized turbulence in collisionless plasmas. We further examine the dynamic alignment and find a weaker scale dependence of the alignment angle than previously proposed. The dominant thermal fluctuations in the kinetic range can cause flattening of the turbulent velocity structure function and weakening of the turbulence anisotropy and dynamic alignment near the kinetic scales.
[abstract 5 / 41] Yes (score: 4) - Title: Multi-Tracer Cross-Correlations of the Unresolved $γ$-Ray SkyAuthors: B. Thakore, M. Regis, M. Negro, S. Camera, D. Gruen, N. Fornengo, A. Roodman,Comments: 29 pages, 9 figures, Submitted to JCAP for publicationSubjects: astro-ph.CO astro-ph.HECreated: 2026-04-23; Updated: 2026-04-24; Datestamp: 2026-04-24
Our understanding of the $γ$-ray sky has greatly advanced, yet studying the unresolved $γ$-ray background (UGRB) can unveil the nature of the faintest $γ$-ray source populations in the Universe. Statistical cross-correlations between the UGRB and tracers of large-scale cosmic structure allow us to infer which sources contribute the most to this emission. In this work, we examine the angular correlation between the UGRB and the matter distribution traced by galaxies, using twelve years of FERMI Large Area Telescope (LAT) observations along with three years of Dark Energy Survey (DES) data. We detect a correlation with a signal-to-noise ratio of 7.85, primarily driven by large angular scales. We then perform a multi-tracer analysis that combines this measurement with the cross-correlation between $γ$ rays and DES weak lensing. The two single-tracer results are mutually consistent, and their combination yields a total significance of 10.31, firmly establishing the extragalactic origin of the UGRB. Intriguingly, the properties inferred for the sources contributing to the UGRB show departures from those of the resolved γ-ray population, suggesting that the faint end of the $γ$-ray sky is not a simple extrapolation of currently resolved sources.
[abstract 6 / 41] 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: 25 pages, to appear in A&ASubjects: astro-ph.GA astro-ph.HECreated: 2026-04-23; Updated: 2026-04-24; Datestamp: 2026-04-24
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 7 / 41] Yes (score: 4) - Title: Multi-wavelength study of EP250416a / GRB 250416C: An Optically Dark Long GRB with a Late Jet BreakAuthors: Guoying Zhao, Duo-Le Cao, Rong-Feng Shen, Hui Sun, Chi-Chuan Jin, Wei-Min Yuan, Chen-Wei Wang, Shao-Lin Xiong, Dmitry Svinkin, Dong Xu, Shuai-Qing Jiang, Peter G. Jonker, Yun Wang, Hao Zhou, Chang Zhou, Xinlei Chen, Kaushik Chatterjee, Xue-Feng Wu, Xiao-Feng Wang, Chun Chen, Yuan Liu, Andrew J. Levan, Jennifer Alexandra Chacon Chavez, Jonathan Quirola-Vásquez, Franz E. Bauer, Antonio Martin-Carrillo, Gregory Corcoran, Daniele B. Malesani, Dmitry Frederiks, Anna Ridnaia, Alexandra L. Lysenko, Mikhail Ulanov,Comments: 12 pages, 14 figures, 4 tables, submitted to Astronomy & AstrophysicsSubjects: astro-ph.HECreated: 2026-04-23; Updated: 2026-04-24; Datestamp: 2026-04-24
We present multi-wavelength study of the $γ$/X-ray transient EP250416a (also designated GRB 250416C), triggered by the Einstein Probe (EP) Wide-field X-ray Telescope and also by SVOM and Konus-Wind. Observations spanning the gamma-ray, X-ray, and optical bands facilitated detailed analysis of the burst's prompt emission, afterglow evolution, and physical origin. EP250416a exhibits a burst duration of 30 s in X-ray and 17.7 s in gamma-rays, with joint spectral fitting of 0.5-5000 keV data gives $E\rm_{peak}=342_{-232}^{+90}$ keV. Optical spectroscopy of the afterglow, acquired with the Gemini Multi-Object Spectrograph (GMOS) on Gemini South, yielded a redshift of $z=0.963$. Accounting for the measured redshift, the isotropic energies are $E\rm_{X,iso}=2.7_{-0.5}^{+0.9}\times10^{50}$ erg and $E\rm_{γ,iso}=7.34_{-2.1}^{+5.1}\times10^{51}$ erg, aligning with the Amati relation for long GRBs. The fluence ratio $\rm S(25-50~keV)/S(50-100~keV)=0.78_{-0.15}^{+0.1}$ classifies EP250416a as an X-ray rich (XRR) GRB. The X-ray afterglow shows an initial shallow decay ($α\approx -0.5$) transitioning to a canonical decay phase ($α\approx -1$), with a very late JET break at $t\sim 1.5\times 10^6$ s, corresponding to a JET half-opening angle of $θ_j=10.6_{-1.8}^{+1.9}$ degrees. EP250416a is optically dark, as it shows only a faint $r$-band detection ($r=24.16$ mag) from Gemini South-GMOS and a low optical-to-X-ray spectral index $β_{\rm OX} = 0.3$. This may be attributed to significant host-galaxy extinction, with a required $A_V^{\text{host}}=5.5\ \text{mag}$ derived from the extinction curve model.
[abstract 8 / 41] Yes (score: 4) - Title: Tracking Magnetic Topological Change in a Time-Dependent Coronal ModelAuthors: Emily I. Mason, Cooper Downs, Roberto Lionello, Jon A. Linker, Viacheslav Titov,Comments: 14 pages, 5 figuresSubjects: astro-ph.SRCreated: 2026-04-23; Updated: 2026-04-24; Datestamp: 2026-04-24
We apply the slip-back mapping method of Titov et al. 2009 and Lionello et al. 2020 to a thermodynamic MHD simulation to track topological changes in the MAGNETic field at a range of temporal cadences. The method constitutes the logical successor to a simple open-field map for a steady-state model, as it tracks changes in the open and closed fields for a time-dependent model by tracking individual MAGNETic elements as they advect across the map, rather than simply tracing field line connectivity from each cell. Through careful categorization of the slip-back mapping values and analysis of the flux changes, we not only effectively track the open flux but can recover the flux processed through interchange RECONNECTion as well. The field lines involved in these processes are shown to follow lines of high squashing factor, as proposed by interchange RECONNECTion-driven slow solar wind theory. The time-dependent model, which is scaled to solar minimum-like activity, projects that a median value of 3.5% of the total open flux in any given 24-hour interval has been processed through interchange RECONNECTion. This corresponds to a relatively high proportion of the total open flux changes over time in the heliosphere. Our results show that not only is this method a useful tool for accurately tracking topological change in time-dependent simulations, but that its inherent complexity can be visually reduced into an intuitive 2D plot that simply and effectively communicates temporal changes.
[abstract 9 / 41] (score: 3) - Title: Revisiting radio SYNCHROTRON diagnostics in star-forming galaxiesAuthors: Maria Werhahn, Christoph Pfrommer, Philipp Girichidis, Joseph Whittingham, Léna Jlassi, Rüdiger Pakmor, Rebekka Bieri, Rainer Weinberger, Volker Springel, Freeke van de Voort,Comments: 19 pages, 14 figures. Submitted to MNRASSubjects: astro-ph.GA astro-ph.HECreated: 2026-04-22; Updated: 2026-04-24; Datestamp: 2026-04-24
Radio continuum observations are widely used to study COSMIC RAY (CR) electron populations and transport processes in star-forming galaxies, but their interpretation relies on several simplifying assumptions. Here, we revisit three common assumptions: that some vertical radio profiles can be explained by CR advection alone, that radio spectra directly trace the galaxy-wide CR electron spectrum, and that bremsstrahlung and Coulomb losses are negligible for radio-emitting electrons. We model radio emission using time-dependent CR electron evolution in a MAGNETohydrodynamical simulation of an isolated Milky Way-mass galaxy. CR electron spectra are evolved self-consistently along Lagrangian tracer particles with the CREST framework, including injection at SUPERNOVA remnants, advection with the gas, and spatially and temporally varying radiative losses. We compare these results to commonly adopted steady-state models. We find that advection-only transport in self-consistently driven galactic winds fails to reproduce the extended vertical radio intensity profiles observed in edge-on galaxies, despite reproducing the observed steepening of spectral indices with height. This is because slowly accelerating winds keep electrons in strong cooling environments for too long. Matching observed radio haloes with advection alone requires unrealistically high midplane wind velocities, implying that additional transport or re-acceleration processes are required. Although galaxy-integrated CR electron spectra at radio-emitting energies are similar across models, the resulting SYNCHROTRON spectra differ systematically because radio emission is biased toward young electrons in dense, strongly MAGNETised regions. Finally, we show that bremsstrahlung and Coulomb losses significantly shape radio spectra even when their loss rate is subdominant and therefore cannot be neglected.
[abstract 10 / 41] (score: 3) - Title: Black hole mass, host galaxy mass, and DARK MATTER halos: Testing the environmental connectionAuthors: G. Mountrichas, F. Shankar, F. J. Carrera, A. Georgakakis,Comments: A&A accepted for publication, 10 pages, 4 figures, 3 tables, the abstract has been abridgedSubjects: astro-ph.GA astro-ph.COCreated: 2026-04-22; Updated: 2026-04-24; Datestamp: 2026-04-24
We investigate the connection between supermassive BLACK HOLEs (SMBHs), their host galaxies, and large-scale dark-matter halos using broad-line X-ray AGN from the XMM--XXL and Stripe\,82X surveys, together with galaxies from VIPERS and SDSS/Stripe\,82. Building on the homogeneous host-galaxy catalogue presented in Paper~I, we test whether AGN with a given black-hole mass, $M_{\rm BH}$, inhabit different large-scale environments from non-AGN galaxies with similar host properties. We first examine the empirical $M_{\rm BH}$--$M_{\star}$ relation of the AGN sample. We find a shallow trend with substantial scatter, likely driven by flux-limited selection effects and uncertainties in virial black-hole mass estimates. The ratio $M_{\rm BH}/M_{\star}$ decreases with increasing stellar mass, and AGN lying above and below the empirical relation show different median host properties, consistent with non-synchronous SMBH and stellar growth. We then divide the AGN into two black-hole mass bins, $8.0 \le \log(M_{\rm BH}/M_\odot) < 8.5$ and $8.5 \le \log(M_{\rm BH}/M_\odot) < 9.0$, and construct galaxy control samples matched in $M_{\star}$, SFR, and sSFR using a multivariate nearest-neighbour method. From AGN--galaxy cross-correlation functions, we infer the characteristic halo masses of AGN and matched galaxies. In the lower-$M_{\rm BH}$ bin, AGN occupy halos statistically indistinguishable from those of their controls. In the higher-$M_{\rm BH}$ bin, we find a mild indication that AGN may reside in somewhat more massive halos, with a difference of about 0.4 dex, although still consistent within the uncertainties. If confirmed with larger samples, this would suggest that halo-scale processes become important mainly at the highest $M_{\rm BH}$.
[abstract 11 / 41] (score: 3) - Title: Chaotic migration of LISA Extreme Mass Ratio Inspirals in a turbulent accretion disk: effect on waveform de-phasingAuthors: Mudit Garg, Lucio Mayer, Yinhao Wu, Yacine Ali-Haïmoud, Douglas N. C. Lin,Comments: 12 pages, 3 figures. Submitted to ApJL. Comments welcomeSubjects: astro-ph.GA astro-ph.HE gr-qcCreated: 2026-04-22; Updated: 2026-04-24; Datestamp: 2026-04-24
Gravitational wave (GW) detector LISA will observe near-coalescence extreme mass ratio inspirals (EMRIs), which typically form in galactic central accretion disks. Gas torques on EMRI will alter its GW-driven inspiral trajectory from the vacuum expectation, leading to potentially LISA-observable GW dephasing ($Δψ_{\rm gas}$). Most studies compute $Δψ_{\rm gas}$ for a thin, laminar disk, with negligible flow turbulence, where the disk exerts a fairly well-understood linear torque ($T_{\rm lin}$). However, these disks must be turbulent due to MAGNETo-rotational instability in the inner regions. Hence, we present a proof-of-concept general, agnostic prescription for the turbulent torque ($T_{\rm turb}$) acting on an EMRI by modeling it as a Gaussian distribution around $T_{\rm lin}$, based on recent advances from a global hydrodynamical (HD) study. We compute $Δψ_{\rm gas}$ for the ``golden'' circular EMRI with total source mass $M=10^6~{\rm M}_\odot$ and mass ratio $q=5\times10^{-5}$ in its final four-year evolution at redshift $z=0.276$ and signal-to-noise ratio (SNR) $=50$ by varying Eddington ratio ${\rm f}_{\rm Edd}$, turbulence normalization $C$ ($=~360$ in the aforementioned HD study), disk aspect ratio $h_0$, and turbo-viscous coefficient $α$ in a reasonable parameters space. We find that for ${\rm f}_{\rm Edd}\gtrsim0.3$, $C\gtrsim300$, $h_0\gtrsim0.03$, and $α\gtrsim0.1$, gas-induced dephasings are unobservable if only considering $T_{\rm lin}$ but could become detectable ($Δψ_{\rm gas}>8/$SNR) if EMRIs exhibit chaotic migration due to turbulent gas flow. Hence, this work motivates running MHD simulations of accretion disks with embedded LISA EMRIs in the early in-spiral phase over long enough timescales to understand the evolution of their orbital elements and the imprint of the turbulent environment on their gravitational waveforms.
[abstract 12 / 41] (score: 3) - Title: Probing Supermassive Black Hole Mergers with Pulsar Timing ArraysAuthors: Hippolyte Quelquejay Leclere,Comments: 10 pages, 5 figures, submitted to PRDSubjects: astro-ph.HE gr-qcCreated: 2026-04-22; Updated: 2026-04-24; Datestamp: 2026-04-24
By monitoring the times of arrival of radio pulses from millisecond pulsars, Pulsar Timing Arrays (PTAs) serve as unique gravitational wave (GW) laboratories in the nanohertz band. To date, the primary astrophysical sources of GWs targeted in this frequency range have been inspiraling supermassive BLACK HOLE binaries (SMBHBs) on circular and eccentric orbits. In this work, we demonstrate that, thanks to the so-called pulsar term in the timing residual waveform of GW signals, PTAs can probe individual SMBHBs that merged before timing observations began. We refer to the latter as \emph{zombie binaries}. Using SMBHB population models consistent with current PTA constraints, we find that while the probability of detecting such systems in existing PTA datasets remains low, the Square Kilometer Array observatory is expected to achieve sufficient sensitivity to have a few zombie binaries with a signal-to-noise ratio exceeding 3 in its data. Although their confident identification might be challenging, this new class of PTA sources opens a novel window for studying the most massive SMBHBs in our local universe.
[abstract 13 / 41] (score: 3) - Title: Investigation of White-light Emission in Compact FlaresAuthors: Yongliang Song,Comments: accepted by ApJSubjects: astro-ph.SRCreated: 2026-04-23; Updated: 2026-04-24; Datestamp: 2026-04-24
White-light flares (WLFs) are usually tend to be those very large flares. Nevertheless, several small and compact WLFs have been reported and thought to be produced by low-height MAGNETic RECONNECTion. However, whether low-height MAGNETic RECONNECTion can efficiently produce WLFs remains unclear. For the first time, we conduct a statistical study of the WL emission in compact flares to address this question. Using over a decade observations from the \textit{Solar Dynamics Observatory} (SDO), we identify 28 compact flares, including 19 C-class and 9 B-class flares. We find these compact flares can be classified into three types based on the MAGNETic configuration of the flare, corresponding to the U-shape loop (type I), the flux emergence near sunspot (type II), and the fan-spine like structure (type III). For each type, the flares numbers are 9 (7 C-calss and 2 B-class), 9 (3 C-calss and 6 B-calss) and 10 (9 C-calss and 1 B-calss), respectively. We find the occurrence rate of WLFs in compact flares is $\sim60.7\%$ (17/28), and for the C-class the rate can be up to $\sim89.5\%$ (17/19). No WLF was found in B-class compact flares. The occurrence rates for three types are $\sim77.8\%$ (7/9), $\sim11.1\%$ (1/9) and 90\% (9/10), respectively. And for the C-class flares, the occurrence rates for three types are 100\% (7/7), $\sim33.3\%$ (1/3) and 100\% (9/9), respectively. Our results suggest type-I and type-III compact flares are more likely to produce WL emissions.
[abstract 14 / 41] (score: 3) - Title: XRISM High-Resolution X-ray Spectroscopy of Cygnus X-1 -- highly ionized Iron absorption structuresAuthors: Shinya Yamada, Natalie Hell, Elisa Costantini, Oluwashina Adegoke, McKinley Brumback, Paul Draghis, Ken Ebisawa, Javier A. Garcia, Edmund Hodges-Kluck, Shunji Kitamoto, Shogo Kobayashi, Takayoshi Kohmura, Aya Kubota, Jon M. Miller, Misaki Mizumoto, Tsunefumi Mizuno, Kaito Ninoyu, Hiromitsu Takahashi, Yuusuke Uchida, Kazutaka Yamaoka, Sixuan Zhang,Comments:Subjects: astro-ph.HECreated: 2026-04-23; Updated: 2026-04-24; Datestamp: 2026-04-24
We present the first high-resolution X-ray spectral analysis of Cygnus X-1 using XRISM. The observation was carried out from April 7 to 10, 2024, covering the orbital phase range 0.65--0.17 during its low/hard state. Taking advantage of the exceptional energy resolution of the Resolve instrument, we examined highly ionized iron absorption lines and characterized the ionization states, column densities, and line-of-sight velocities of the absorbing plasma. Spectral analysis revealed an ionization parameter of approximately 3, column densities of a few times 10^21 cm^-2, and a blueshifted velocity of approximately 100 km s^-1. The observation was divided into two phases: before and after orbital phase phi_orb = 0.9, corresponding to non-dipping and dipping intervals. While only weak absorption features were present before phi_orb = 0.9, strong absorption by He-like and H-like Fe appeared during the dipping phase. We measured equivalent widths of 2.3 eV, 0.4 eV, and 1.2 eV for He-like Fe K-alpha, and H-like Ly-alpha1 and Ly-alpha2, respectively, demonstrating the capability of XRISM Resolve to securely detect narrow absorption features of only a few eV. These measurements trace the motion of the absorbing material and offer insight into the kinematics and spatial distribution of the wind in the vicinity of the BLACK HOLE. These findings enhance our understanding of wind-fed accretion in Cygnus X-1 and highlight the importance of continued high-resolution X-ray observations to further constrain the physical properties of winds and accretion flows in high-mass X-ray binaries.
[abstract 15 / 41] (score: 3) - Title: XRISM High-Resolution X-ray Spectroscopy of Cygnus X-1 -- Orbital and Short-Term Variability of Iron AbsorptionAuthors: Kaito Ninoyu, Shinya Yamada, Natalie Hell, Elisa Costantini, Oluwashina Adegoke, Paul Draghis, Ken Ebisawa, Javier A. Garcia, Edmund Hodges-Kluck, Shunji Kitamoto, Shogo Kobayashi, Takayoshi Kohmura, Aya Kubota, Jon M. Miller, Misaki Mizumoto, Tsunefumi Mizuno, Hiromitsu Takahashi, Yuusuke Uchida, Kazutaka Yamaoka, Sixuan Zhang, Ryota Tomaru, Seoru Ito,Comments: PASJ accepted on 2026/03/06Subjects: astro-ph.HECreated: 2026-04-23; Updated: 2026-04-24; Datestamp: 2026-04-24
We present the first high-resolution spectroscopy of the BLACK HOLE high-mass X-ray binary Cygnus X-1 with XRISM, including orbital-phase-resolved analyses and tentative evidence of short-term variability in the Fe-K band on second timescales. Using data from the Performance Verification phase in April 2024, we analyzed spectral variability across orbital phases with the Resolve microcalorimeter and the Xtend CCD imager. The unprecedented resolution of Resolve reveals variability in highly ionized Fe absorption lines. The absorption features show orbital-phase-dependent variability in column density, ionization state, and blueshifted velocity, suggesting structural variations in the focused stellar wind along the line of sight. We also find indications of subtle broadening of the neutral Fe emission profile. In addition, intensity-sorted spectroscopy during dip phases suggests possible variability on timescales of a few seconds in the absorption features, consistent with cooler, denser and lower-ionized gas clumps. Although the statistical significance is limited, these results hint that the stellar wind and the X-rays from the accretion disk around the BLACK HOLE may interact on timescales as short as a few seconds. These XRISM results constrain wind-fed accretion in Cyg X-1 and highlight Resolve's capability to probe plasma environments in high-mass X-ray binaries.
[abstract 16 / 41] (score: 3) - Title: Impact of Primordial Black Hole population on 21 cm observables at high redshiftAuthors: Atrideb Chatterjee, Barun Maity, Koushiki,Comments: Submitted to A&ASubjects: astro-ph.CO gr-qcCreated: 2026-04-23; Updated: 2026-04-24; Datestamp: 2026-04-24
The 21-cm signal, one of the most promising probes of the high-redshift Universe, has traditionally been modelled without accounting for the effects of ACTIVE GALACTIC NUCLEi (AGN) in the pre-JWST era, primarily due to the lack of observational evidence for AGNs at z > 6. However, following the discovery of several AGNs at redshifts as high as z ~ 10 by JWST, it has become imperative to incorporate the impact of these early AGNs when predicting the 21-cm signal. Supposing that these AGNs are seeded by primordial BLACK HOLEs (PBHs), we study their impact with a semi-numerical model setup. Specifically, we extended the explicitly photon-conserving reionization framework, SCRIPT, including essential cosmic dawn physics and PBH contributions. This enables us to compute both the global signal and the power spectrum of the 21-cm line over the redshift range z ~ 30 - 5 within a self-consistent framework. Building on this setup, we then investigate the impact of different PBH mass functions (obeying current observational constraints) on the resulting signal. The X-ray heating from PBHs can substantially make the depth of the global 21-cm signal shallower and suppress the expected power amplitude during cosmic dawn. We also find that the choice of mass function plays a crucial role in shaping the 21-cm signal, and can, in fact, lead to significantly different predictions.
[abstract 17 / 41] (score: 3) - Title: Magnetar Engines in Broad-lined Type Ic Supernovae and a Unified Picture for Magnetar-powered Stripped-envelope SupernovaeAuthors: Jin-Ping Zhu, Bing Zhang,Comments: 39 pages, 17 figures, 3 tables, Comments are welcome!Subjects: astro-ph.HE astro-ph.SRCreated: 2026-04-23; Updated: 2026-04-24; Datestamp: 2026-04-24
We model the multi-band lightcurves of 80 SNe Ic-BL, including 11 associated with lGRBs, using a MAGNETar engine model with $^{56}$Ni decay. We find that the data are all consistent with a MAGNETar central engine, and such a model yields high-quality fits across the sample. The medians with $1σ$ regions of the key parameters are $P_{\rm{i}}\sim2.04^{+1.84}_{-0.96}\,{\rm{ms}}$, $B_{\rm{p}}\sim3.96^{+3.28}_{-1.40}\times10^{15}\,{\rm{G}}$, $M_{\rm{ej}}\sim2.30^{+1.48}_{-1.02}\,M_\odot$, and $M_{\rm{Ni}}\sim0.18^{+0.14}_{-0.09}\,M_\odot$, with strong and statistically significant correlations observed for both $M_{\rm{ej}}-P_{\rm{i}}$ (anti-correlation) and $M_{\rm{Ni}}-M_{\rm{ej}}$ (correlation). Comparing the SN Ic-BL samples with and without lGRB association using fitting parameters, we find no significant difference between them, although the GRB-associated sample is slightly brighter, possibly due to an observational bias. Relative to ordinary SNe Ic, SNe Ic-BL have similar $^{56}$Ni and ejecta masses, suggesting comparable pre-SN progenitor properties, with differences possibly arising from the presence of a MAGNETar engine. In comparison with other possible MAGNETar-powered SESNe, including SLSNe Ic and FBOTs, we confirm a strong universal $M_{\rm{ej}}-P_{\rm{i}}$ correlation, indicating a common origin. SNe Ic-BL and SLSNe Ic have similar ejecta mass distributions, typically $M_{\rm ej}\gtrsim0.5\,M_\odot$, while FBOTs mostly lie below this value. Differences between SNe Ic-BL and SLSNe Ic may arise from MAGNETar properties, with SN Ic-BL MAGNETars rotating faster and having stronger fields. Moreover, the $P_{\rm{i}}-B_{\rm{p}}$ distribution of lGRB MAGNETars largely overlaps with that of SN Ic-BL MAGNETars. In connection with binary simulation results, we propose a unified physical classification and progenitor framework for MAGNETar-powered and ordinary SESNe.
[abstract 18 / 41] (score: 3) - Title: Orbital angular momentum radiation and POLARIZATION of RELATIVISTIC electrons in MAGNETic fieldsAuthors: Ziqiang Huang, Qi Meng, Xuan Liu, Wei Ma, Zhen Yang, Liang Lu, Alexander J. Silenko, Pengming Zhang, Liping Zou,Comments:Subjects: physics.acc-ph hep-thCreated: 2026-04-23; Updated: 2026-04-24; Datestamp: 2026-04-24
While spin POLARIZATION from SYNCHROTRON radiation is well established, the POLARIZATION of orbital angular momentum (OAM) in such radiative processes remains elusive. We study radiation and POLARIZATION of RELATIVISTIC electrons in a uniform MAGNETic field, focusing on OAM POLARIZATION radiation for vortex electrons which carry intrinsic OAM. The results illustrate that transition rates are asymmetric in the low-photon-energy regime, favoring OAM decrease, analogous to the spin-flip asymmetry in the Sokolov-Ternov effect. Under these conditions, SYNCHROTRON radiation can polarize the OAM. The characteristic relaxation time and stationary-state OAM distribution are obtained analytically. The POLARIZATION of spin about \(\mathcal{P}_{\text{spin}}\) reaches \(92.38\%\), while that of \(\mathcal{P}_{\text{OAM}}\) can even approach almost unity for a large OAM; however, their POLARIZATION behaviors are different. For typical storage ring parameters, the OAM POLARIZATION time is orders of magnitude shorter than the spin POLARIZATION time. Thus, SYNCHROTRON radiation offers a mechanism for controlling vortex electron beams which carry OAM for high-energy accelerator applications.
[abstract 19 / 41] (score: 2) - Title: Time-reversed Shannon entropy as a chaos indicator for non-integrable systemsAuthors: Wenfu Cao, Siyan Chen, Hongsheng Zhang,Comments: 16 pages, 5 figuresSubjects: gr-qcCreated: 2026-04-23; Updated: 2026-04-24; Datestamp: 2026-04-24
We propose a novel chaos indicator -- time-reversed Shannon entropy (TRSE) -- that leverages the interplay between time-reversal symmetry breaking and information entropy in curved spacetimes. By quantifying statistical discrepancies between forward and backward temporal evolution of particle orbits, TRSE robustly distinguishes chaotic from regular dynamics in non-integrable systems. In contrast, integrable systems exhibit stable, symmetric probability distributions preserved by conserved quantities such as the Carter constant. We validate the method through high-precision numerical simulations in both Kerr and Schwarzschild-Melvin BLACK HOLE geometries, evolving trajectories forward and backward in time. Furthermore, we refine our previously introduced particle-pair mutual information (MIPP) and perform comprehensive parameter-space scans, revealing a strong quantitative agreement between MIPP and TRSE. The two indicators emerge as complementary probes of chaos: TRSE captures symmetry breaking in orbital evolution, while MIPP measures statistical correlations. Together, they establish a unified framework for diagnosing chaos in general RELATIVISTIC systems, paving a new path to understand the fundamental nature of chaos in non-integrable systems.
[abstract 20 / 41] (score: 2) - Title: SED and Galactic kinematic diagnostics for dormant BH/NS binary candidatesAuthors: Qian-Yu An, Wei-Min Gu,Comments: 10 pages, 3 figures, 1 table, accepted for publication in ApJLSubjects: astro-ph.SR astro-ph.GA astro-ph.HECreated: 2026-04-23; Updated: 2026-04-24; Datestamp: 2026-04-24
The third data release of the Gaia mission (Gaia DR3) has enabled large-scale searches for dormant BLACK HOLE and neutron star binaries with stellar companions at AU-scale separations. A recent study has proposed thousands of dormant BLACK HOLE and neutron star binary candidates using summary statistics from Gaia DR3 by simulating and fitting Gaia observables. In this work, we perform broadband spectral energy distribution (SED) fitting from the optical to the infrared for 1,328 candidates, incorporating GALEX ultraviolet photometry to assess the presence of hidden hot companions. We quantify ultraviolet excess by comparing observed near-ultraviolet fluxes with single-star SED predictions and further test whether excesses can be explained by non-degenerate stellar companions for sources exhibiting moderate excess. We additionally examine the Galactic kinematics of the sample to identify systems potentially affected by natal kicks during compact-object formation. By combining the ultraviolet and kinematic diagnostics, we identify 182 sources as the highest-priority candidates for follow-up observations, in which 19 are BLACK HOLE candidates with fit_companion_mass $\geq$ 3 $M_\odot$.
[abstract 21 / 41] (score: 2) - Title: Subaru High-$z$ Exploration of Low-Luminosity Quasars (SHELLQs). XXV. Large-scale environments of low-luminosity QUASARs at $z\sim6$ traced by Ly$α$ emittersAuthors: Junya Arita, Nobunari Kashikawa, Yoshiki Matsuoka, Masafusa Onoue, Michael A. Strauss, Kentaro Koretomo, Yoshihiro Takeda, Ryo Emori, Wanqiu He, Hiroki Hoshi, Masatoshi Imanishi, Rikako Ishimoto, Kei Ito, Kazushi Iwasawa, Satoshi Kikuta, Yongming Liang, Camryn L. Phillips, Shunta Shimizu, John D. Silverman, Yoshiki Toba, Takehiro Yoshioka,Comments: 19 pages, 16 figures, accepted for publication in MNRASSubjects: astro-ph.GACreated: 2026-04-23; Updated: 2026-04-24; Datestamp: 2026-04-24
High-$z$ QUASARs are believed to reside in massive DARK MATTER haloes (DMHs), suggesting that they reside in galaxy overdense regions. However, previous observations have shown a range of environments around them. These fields have been limited to luminous QUASARs ($M_{1450}\lesssim-25$), for which photoevaporation may hinder galaxy formation in their vicinity. Here, we present Subaru/Hyper-Suprime Cam observations of the environments of four low-luminosity QUASARs ($-24
[abstract 22 / 41] (score: 2) - Title: On non-vacuum BLACK HOLEs in new general relativityAuthors: D. F. López, A. A. Coley, B. Yildirim,Comments:Subjects: gr-qcCreated: 2026-04-22; Updated: 2026-04-24; Datestamp: 2026-04-24
New general relativity (NGR) is a torsion-based modification of general relativity whose Lagrangian depends on three free parameters, $(c_{a}, c_{v}, c_{t})$. A subset of the parameter space is physically admissible, namely that which simultaneously ensures ghost-freedom, propagation of a spin-2 mode, and a consistent Newtonian limit. In this work we analyze static and spherically symmetric configurations in NGR, both in vacuum and in the presence of a perfect fluid and an electroMAGNETic field, under the assumption of the existence of a local black-hole horizon. We find that the mere existence of such configurations forces the free parameters into regions associated with known pathological models: theories that either contain ghost instabilities, do not propagate a spin-2 mode, or lack a Newtonian limit. The remaining geometries are regular at the horizon, so the obstruction is not a breakdown of the geometry but a breakdown of the underlying theory. We therefore conclude that, within the class of models examined, NGR does not admit physically meaningful non-trivial BLACK HOLEs distinct from those of the teleparallel equivalent of general relativity.
[abstract 23 / 41] (score: 2) - Title: Consistent Treatment of Muons in Binary Neutron Star MergersAuthors: Henrique Gieg, Ramon Jaeger, Maximiliano Ujevic, Tim Dietrich,Comments: 12+7 pages, 5 figures. Version matching journal submission after feedbackSubjects: astro-ph.HE gr-qcCreated: 2026-04-23; Updated: 2026-04-24; Datestamp: 2026-04-24
We present a set of numerical-relativity binary neutron star merger simulations incorporating muons and muonic reactions for two baseline baryonic equations-of-state. In order to investigate the possible impact of muons and muonic weak reactions, we treat neutrinos with a gray (energy-independent) truncated moments scheme and an implicit-explicit time integrator. Newly computed neutrino rates are employed within the full kinematics approach for a set of relevant reactions, and pair-processes are modeled via opacities computed using reaction kernels, that allow a consistent treatment of neutrino interaction rates. We find that equilibration between matter and radiation is successfully captured by a novel two timescales approach. Of astrophysical interest is the general agreement between our muonic and non-muonic results regarding the remnant evolution, disk and outflow properties. Average electron fractions, asymptotic velocities and temperatures are different by less than $\sim 6\%$, while the main impact of muons is a reduction in ejecta masses by at most $\sim 17\%$. Therefore, based on our findings, accounting for the presence of muons and muonic reactions might result much less severe consequences regarding nucleosynthetic yields and electroMAGNETic counterparts than previously reported in the literature.
[abstract 24 / 41] (score: 2) - Title: Deep VLBI constraints on compact radio cores in four ultraluminous X-ray sourcesAuthors: Ailing Wang, Hua Feng, Tao An, Yijia Zhang, Jun Yang, Roberto Soria, Lian Tao, Thomas Russell, Jing Guo, Liang Zhang,Comments: This paper has been accepted for publication in The Astrophysical JournalSubjects: astro-ph.HECreated: 2026-04-23; Updated: 2026-04-24; Datestamp: 2026-04-24
We present high-sensitivity Very Long Baseline Interferometry (VLBI) observations of four ultraluminous X-ray sources (ULXs): Holmberg II X-1, IC 342 X-1, NGC 6946 X-1, and NGC 925 X-1. No compact emission was detected on milliarcsecond scales, with rms noise levels reaching approximately 5--20 $μ$Jy. The corresponding $5σ$ flux density upper limits reach $\sim 26\,μ\mathrm{Jy}$, implying radio luminosity limits $L_{\rm R} \lesssim 2 \times 10^{33}\,\mathrm{erg\,s^{-1}}$. This disfavors any persistently bright hard-state-like compact core at our sensitivity level. The previously reported VLBI core in Holmberg II X-1 exhibits significant long-term variability, broadly consistent with an overall decline over the past decades. This behavior is consistent with emission from optically-thin ejecta undergoing adiabatic expansion. The VLBI non-detections may reflect intrinsically weak/intermittent compact emission, and/or low--surface--brightness structure that is resolved out by VLBI, and/or absorption/propagation effects such as free--free absorption in dense, ionized winds.
[abstract 25 / 41] (score: 2) - Title: Interpretable Analytic Formulae for GWTC-4 Binary Black Hole Population Properties via Symbolic RegressionAuthors: Chayan Chatterjee,Comments:Subjects: astro-ph.CO astro-ph.HE gr-qcCreated: 2026-04-22; Updated: 2026-04-24; Datestamp: 2026-04-24
Recent LIGO-Virgo-KAGRA (LVK) analyses have revealed complex structure in the binary BLACK HOLE (BBH) population, including distinct features in the primary mass spectrum and nontrivial spin-mass correlations. However, the phenomenological models used to capture these features often lack analytic transparency, making it difficult to isolate robust physical laws from modeling artifacts. To address this, symbolic regression is applied to the posterior inference products of the GWTC-4 catalog, discovering compact, closed-form analytic expressions for four key population relationships: (i) the merger-rate evolution with redshift; (ii) the mass-ratio dependence of the effective-spin distribution; (iii) the redshift evolution of the effective-spin distribution; and (iv) the conditional mass-ratio distributions associated with the 10 solar mass and 35 solar mass primary mass peaks. This framework successfully compresses both rigid and highly flexible models into differentiable phenomenological laws, dynamically recovering a consistent low-redshift merger-rate slope without assuming an a priori power-law form. The exact analytic derivatives provided by symbolic regression show that the mass ratio--effective spin and redshift--effective spin correlations are robustly driven by broadening of the posterior widths rather than shifts in the mean. Furthermore, qualitatively distinct functional forms for the mass-ratio distributions conditioned on the 10 solar mass and 35 solar mass primary mass peaks are identified. These closed-form expressions enable exact analytic gradient diagnostics and compact surrogate summaries, particularly for flexible numerical posteriors that are not otherwise available in low-dimensional analytic form. They also facilitate rapid downstream calculations for rate forecasting, formation channel comparison, and stochastic background estimation.
[abstract 26 / 41] (score: 2) - Title: Surfactant effect on collective bubble bursting and aerosol emissionAuthors: Megan Mazzatenta, Samuel M. Koblensky, Luc Deike,Comments: 10 pages, 4 figures, plus Supplementary Information (6 pages, 4 figures, 1 table)Subjects: physics.flu-dyn physics.ao-phCreated: 2026-04-22; Updated: 2026-04-24; Datestamp: 2026-04-24
Bubbles entrained by breaking waves rise to the ocean surface where they cluster and burst, emitting sea spray aerosols into the atmosphere. Bubble bursting thereby links seawater biogeochemistry and aerosol chemistry, influencing the ability of emitted aerosols to serve as cloud condensation nuclei or ice nucleating particles. The mechanisms of film drop and JET drop production are modulated by organic material present in seawater, which may affect the size, number, and composition of resulting aerosols. We disentangle the effect of surfactant on collective bursting processes using laboratory experiments with detailed bubble and aerosol measurements down to small sizes, multiple bubble size configurations, and measurements of bubble lifetime. Submicron aerosol emission, linked to film drop production, increased with surfactant up to an optimal concentration, while production of supermicron aerosols emitted through JET drop production was shut down. Our work paves the way to integrate organic composition into sea spray emission functions.
[abstract 27 / 41] (score: 2) - Title: Archival Multiband Gravitational-Wave Signals from Massive Black Hole Binary MergersAuthors: Alexander W. Criswell, Stephen R. Taylor, Kris Pardo, Alberto Sesana, David Izquierdo, Silvia Bonoli, Daniele Spinoso,Comments: 20 pages, 5 figuresSubjects: astro-ph.HE gr-qcCreated: 2026-04-22; Updated: 2026-04-24; Datestamp: 2026-04-24
While massive BLACK HOLE binaries (MBHBs) merge at gravitational-wave frequencies above the pulsar timing array (PTA) sensitivity band, we show that they leave orphaned low-frequency contributions in the PTA pulsar term. Due to the light-propagation time between each pulsar in the array and Earth, the pulsar term acts as a time-delayed probe of a chirping merger with a specific frequency response determined by the direction of origin and intrinsic properties of the MBHB. We provide a detailed consideration of how such a multiband signal would manifest in a full PTA, demonstrate an approach to stack these orphaned pulsar terms across the array, and discuss prospects for an archival, multiband search in conjunction with MBHB mergers observed in astrometric data or spaceborne interferometers like LISA.
[abstract 28 / 41] (score: 2) - Title: Ultra High Energy Cosmic Rays from the Local VoidAuthors: Michael J. Padgett, Thomas W. Kephart,Comments: 13 pages, 5 figures, 1 tableSubjects: hep-ph astro-ph.HE hep-thCreated: 2026-04-22; Updated: 2026-04-24; Datestamp: 2026-04-24
Ultra high energy COSMIC RAYs have been see coming from the direction of the local cosmic void. We use this fact to argue that at least some of these these COSMIC RAYs are relatively light MAGNETic monopoles and that their relative fraction above 1020 eV can be found from full sky observations.
[abstract 29 / 41] (score: 2) - Title: Quantum Computing Framework for Transient Scattering of ElectroMAGNETic Waves by Dielectric StructuresAuthors: Min Soe, Abhay K. Ram, Efstratios Koukoutsis, George Vahala, Linda Vahala, Kyriakos Hizanidis,Comments: 15 pages, 26 FiguresSubjects: physics.plasm-phCreated: 2026-04-22; Updated: 2026-04-24; Datestamp: 2026-04-24
Quantum computers are ideally set up to solve linear systems which are of a form similar to the Schrodinger/Dirac equation of quantum mechanics. In the framework of linear response theory, the propagation and scattering of electroMAGNETic waves in a dielectric medium are described by Maxwell equations. The qubit lattice algorithm consists of a series of alternating unitary streaming and entanglement operators acting on qubit amplitudes constructed from the electric and MAGNETic fields. It is not a direct discretization of Maxwell equations, but recovers the desired equations to second order in lattice grid spacing. The resulting algorithm is implemented on a present-day supercomputer and is the basis of studying scattering of electroMAGNETic waves by an elliptical dielectric. As opposed to the steady state description of Mie scattering in frequency domain, the temporal evolution provides insights into transient scattering. The QLA simulations, reveal that a spatially localized wave packet propagating past an elliptic dielectric, embedded in vacuum, leads to several reflections generated by wave fields trapped within the dielectric. The physics insight brought forth by these simulations is not apparent from frequency domain studies of scattering. A complimentary simulation on transient scattering of a wave packet by an elliptical vacuum bubble inserted in a uniform dielectric demonstrates a stark contrast with respect to scattering off an elliptical dielectric in vacuum. Essentially, there is only a single internal reflection in which the field amplitudes are significantly smaller than those for side and forward scattering. A simple model based on the Kirchhoff tangent plane approximation helps explain the differences between these two scattering examples.
[abstract 30 / 41] (score: 2) - Title: Orbital evolution of highly eccentric bodies embedded in a ringed accretion discAuthors: R. A. Anaya-Sánchez, F. J. Sánchez-Salcedo,Comments: 16 pages, 19 figures. Accepted for publication in MNRASSubjects: astro-ph.GA astro-ph.EPCreated: 2026-04-22; Updated: 2026-04-24; Datestamp: 2026-04-24
Various processes can induce long-lived overdense rings and arcs in protoplanetary and AGN accretion discs, such as the accumulation of gas at the outer edge of the dead zone, or the infall of material. Using the local approximation of dynamical friction, we investigate the orbital evolution of a low-mass highly-eccentric point-mass accretor (perturber) embedded in an isothermal disc hosting a density ring. We specifically consider the regime in which the eccentricity exceeds four times the disc aspect ratio. For prograde perturbers, orbits that cross the ring progressively circularize while their semi-major axes converge toward the ring radius. As a result, perturbers accumulate, forming a population ring superimposed on the gaseous ring. The ring therefore acts as a migration trap for these eccentric orbits. We also find that prograde orbits tangent to the ring, either at apocentre or pericentre, remain tangential throughout their evolution; perturbers confined to these trajectories experience the highest accretion rates. In contrast, retrograde perturbers always migrate inward. Once the semi-major axis becomes smaller than the ring radius, the eccentricity grows, but not enough for the orbit to intersect the ring again. We also discuss how feedback effects, such as JET launching and thermal torques, could modify the effective forces acting on the perturbers.
[abstract 31 / 41] (score: 2) - Title: Development of Anisotropic Magnetized Viscosity for Magnetized Liner Inertial Fusion Simulations in FLASHAuthors: Ashwyn Sam, Fernando Garcia-Rubio, Scott Davidson, C. Leland Ellison, Jason Hamilton, Raymond Lau, Nathan Meezan, Adam Reyes, Paul Schmit, Alexander Velikovich,Comments:Subjects: physics.plasm-phCreated: 2026-04-22; Updated: 2026-04-24; Datestamp: 2026-04-24
Magnetized liner inertial fusion (MagLIF) operates in a regime where anisotropic transport phenomena fundamentally influence implosion dynamics. In strongly MAGNETized plasmas, the viscous stress tensor becomes highly anisotropic, yet no prior work has incorporated or examined MAGNETized viscosity effects in MagLIF configurations. We present the first implementation of the full Braginskii MAGNETized viscosity tensor for arbitrary MAGNETic field orientations in the Pacific Fusion branch of FLASH. The implementation is verified through analytical comparisons, direct verification against Braginskii's original formulation, Method of Manufactured Solutions, and against analytical shock solutions. Application to MagLIF-relevant configurations reveals that MAGNETized viscosity damps vortical structures, converts kinetic energy in those vortical structures into thermal energy, and mitigates the Rayleigh-Taylor instabilities. Simulations with seeded perturbations demonstrate yield preservation when MAGNETized viscosity is included. These results establish MAGNETized viscosity as a non-negligible physical mechanism in MagLIF plasmas and provide a validated capability for predictive modeling of MAGNETized high-energy-density plasmas.
[abstract 32 / 41] (score: 2) - Title: Uncertainty-Aware Spatiotemporal Super-Resolution Data Assimilation with Diffusion ModelsAuthors: Aditya Sai Pranith Ayapilla, Kazuya Miyashita, Yuki Yasuda, Ryo Onishi,Comments: 35 pages, 17 figuresSubjects: physics.flu-dyn physics.ao-ph physics.comp-phCreated: 2026-04-23; Updated: 2026-04-24; Datestamp: 2026-04-24
Data assimilation (DA) improves prediction of chaotic systems by combining model forecasts with sparse, noisy observations. Many DA methods are inherently probabilistic, but accurate probabilistic DA is often computationally expensive because it requires repeated high-resolution (HR) forecasts and large ensembles. In this study, we develop DiffSRDA, a probabilistic spatiotemporal super-resolution data assimilation framework based on denoising diffusion models, and evaluate it on an idealized barotropic ocean JET instability testbed. DiffSRDA is trained offline to generate short HR analysis windows conditioned on (i) a time series of low-resolution (LR) forecast frames and (ii) sparse HR observations. Repeated reverse diffusion sampling then produces an ensemble of HR analyses, providing both point estimates and uncertainty information. Despite relying only on low-cost LR forecasts, DiffSRDA achieves reconstruction quality close to that of an Ensemble Kalman Filter (EnKF) driven by HR forecasts, while improving over deterministic CNN-based SRDA baselines. The sampled ensemble also yields physically meaningful uncertainty patterns, with spread concentrated in dynamically active regions similarly to EnKF. A key practical result is that accurate base DiffSRDA cycling does not require long reverse chains: most of the full-chain accuracy is retained with only a few reverse steps, making diffusion-based SRDA practical for repeated cycling. Finally, by exploiting the score-based structure of diffusion sampling, we demonstrate training-free observation-consistency guidance for deployment-time sensor-layout shifts, enabling improved use of changed observation configurations without retraining. Overall, diffusion models provide a practical, uncertainty-aware, and computationally efficient approach for spatiotemporal SRDA in chaotic fluid flows.
[abstract 33 / 41] (score: 2) - Title: Geometry, Not Calorimetry, Drives the Radio/Infrared/Gamma-Ray CorrelationAuthors: Troy A. Porter, Igor V. Moskalenko, Gudlaugur Johannesson,Comments: 17 pages, 9 figures. ApJ submittedSubjects: astro-ph.HE astro-ph.GACreated: 2026-04-23; Updated: 2026-04-24; Datestamp: 2026-04-24
We investigate whether the observed radio-infrared-$γ$-ray correlation in star-forming galaxies is a geometric effect rather than a signature of local cosmic-ray (CR) calorimetry. Using the GALPROP framework, we generate synthetic observations for external viewers from a grid of 3D Milky Way models with varied CR source, gas, interstellar radiation, and MAGNETic field distributions, all normalised to reproduce local CR data. We find that a tight, quasi-linear correlation arises naturally from line-of-sight integration through the extended, radially-structured disc, even when local calorimetry is absent. The correlation's properties depend strongly on viewing geometry, preserving its form under moderate inclination but breaking down in edge-on views where galactic components are stratified. We conclude that the correlation is primarily an emergent property of geometric projection, not local physics. This implies that its scatter is likely not random noise but a diagnostic of underlying galactic structure and viewing angle.
[abstract 34 / 41] (score: 2) - Title: Energy Loss of Newborn Magnetars by Schwinger ProcessAuthors: Chul Min Kim, Sang Pyo Kim, Remo Ruffini, Yu Wang, Shurui Zhang,Comments: Comments are welcome!Subjects: astro-ph.HECreated: 2026-04-23; Updated: 2026-04-24; Datestamp: 2026-04-24
We investigate electron--positron pair creation through the Schwinger process in newborn MAGNETars with millisecond spin periods and surface dipole fields close to or above the QED critical field, $B_{\rm Q} = 4.414\times10^{13}\,\mathrm{G}$. In the unscreened field scenario, we derive the analytical global pair creation flux and recast it into a compact form with accurate analytic approximations. For a fiducial model with $B_{\rm p} = 10^{14}\,\mathrm{G}$ and $P_0 = 1\,\mathrm{ms}$, the Schwinger channel exceeds the classical Goldreich--Julian particle supply by many orders of magnitude and becomes the dominant source of charges at the earliest stage of the MAGNETar. The associated discharge removes about $90\%$ of the initial rotational energy within 30 ms, suppresses the gravitational-wave loss channel, and implies that the observable millisecond phase is extremely short in this unscreened scenario. The rapid energy release over such a short timescale may also provide a viable power source for astrophysical transients. Extending the same fiducial model to $10^4\,\mathrm{yr}$ gives spin periods of order seconds, linking newborn millisecond MAGNETars to the mature MAGNETar population.
[abstract 35 / 41] (score: 2) - Title: Cosmological discrete self-similarity in primordial BLACK HOLE formationAuthors: Luis E. Padilla, Tomohiro Harada, Ethan Milligan, David Mulryne,Comments: 10 pages, 9 figures. Comments are welcomeSubjects: astro-ph.COCreated: 2026-04-23; Updated: 2026-04-24; Datestamp: 2026-04-24
We demonstrate that discrete self-similarity (DSS), originally discovered in the collapse of a massless scalar field in an asymptotically flat system, survives in primordial BLACK HOLE (PBH) formation within an expanding cosmological background. Using fully RELATIVISTIC numerical simulations of massless scalar-field collapse in an Friedmann-Lemaître-Robertson-Walker universe, we resolve the critical regime down to $|p-p_c|\sim 10^{-8}$, where $p$ and $p_c$ respectively are a parameter of the family of initial data and its threshold value, and find clear log-periodic oscillations in the PBH mass scaling relation. The detailed structure of these oscillations differs from that previously reported in the asymptotically flat case, exhibiting a more pronounced asymmetry between peaks and troughs. Analyzing two distinct families of initial data (Gaussian and piecewise rational curvature profiles), we find critical exponents and DSS periods that differ slightly but are broadly consistent within uncertainties. The presence of DSS implies characteristic log-periodic modulations in the PBH mass spectrum, with potential consequences for PBH abundances and the spectrum of induced gravitational waves.
[abstract 36 / 41] (score: 2) - Title: Chaotic dynamics of charged particles near weakly MAGNETized BLACK HOLEs in Einstein-ModMax TheoryAuthors: Zijian Liu, Wenfu Cao,Comments: 21 pages, 8 figuresSubjects: gr-qcCreated: 2026-04-23; Updated: 2026-04-24; Datestamp: 2026-04-24
This paper presents a systematic study of the chaotic dynamics of charged test particles around purely MAGNETically charged BLACK HOLEs immersed in a uniform external MAGNETic field within the framework of Einstein-ModMax theory. By constructing an explicit symplectic integrator, we obtain high-precision numerical solutions of the equations of motion. Combining the observational constraints from the Event Horizon Telescope (EHT) shadow images, we further restrict the parameter ranges of the model. We apply Shannon entropy and MIPP (mutual information for particle pairs) as effective indicators to identify the chaotic behavior of charged test particles in the spacetime of this BLACK HOLE. Numerical results indicate that these indicators can clearly distinguish between regular and chaotic motion of orbits in strong gravitational field systems. Further analysis reveals that, compared to the key conserved quantities that determine the global dynamical behavior of the system -- energy $E$ and angular momentum $L$, the sensitivity of the system parameters $e^{-ν}$ and $Q_{m}$ to transitions in the orbital dynamical states is significantly reduced. This study provides a new perspective for a deeper understanding of the characterization and evolution mechanisms of chaotic dynamics in strong gravitational fields.
[abstract 37 / 41] (score: 2) - Title: Exploring the statistical anisotropy of primordial curvature perturbations with pulsar timing arraysAuthors: Fengting Xie, Zhi-Chao Zhao, Qing-Hua Zhu, Xin Li,Comments: 24 pages, 8 figuresSubjects: gr-qc astro-ph.COCreated: 2026-04-23; Updated: 2026-04-24; Datestamp: 2026-04-24
The recent detection of a stochastic gravitational wave background by pulsar timing arrays has opened a new window in understanding supermassive BLACK HOLE binaries and in probing the universe at the early time. Recently, pulsar timing array (PTA) collaborations have been further paving the way to probe anisotropies in the stochastic gravitational wave background. This study investigates dipole-type statistical anisotropy in the primordial power spectrum within a phenomenological framework. We demonstrate that the primordial dipole induces both dipolar and quadrupolar anisotropies in the energy density spectrum of scalar-induced gravitational waves (SIGWs), without generating extra POLARIZATION modes. Based on this anisotropic spectrum, we derive the corresponding PTA overlap reduction functions (ORFs), which exhibit frequency dependence, with the anisotropies enhanced on small scales. Furthermore, owing to the non-uniform distribution of millisecond pulsars over the sky in current PTA dataset, the ORFs exhibit a morphology that explicitly depends on the preferred direction of the anisotropy. However, our bayesian analysis of the NANOGrav 15-year dataset still yields no significant evidence for a preferred direction and a weak upper limit on anisotropy amplitude $(g\lesssim0.5)$. This result arises because the observational frequency band lies below the spectral peak, where our models predict suppressed anisotropic contributions. This limitation highlights the potential of future PTA observations. Specifically, datasets with broader frequency coverage are expected to tighten constraints on dipole-type anisotropy.
[abstract 38 / 41] (score: 2) - Title: Delving into the depths of NGC 3783 with XRISM: V. Broad-band modeling of ionized outflowsAuthors: Keqin Zhao, Jelle S. Kaastra, Liyi Gu, Missagh Mehdipour, Megan E. Eckart, Keigo Fukumura, Matteo Guainazzi, Chen Li, Christos Panagiotou, Matilde Signorini,Comments:Subjects: astro-ph.HECreated: 2026-04-23; Updated: 2026-04-24; Datestamp: 2026-04-24
The Seyfert 1 galaxy NGC 3783 hosts a multiphase warm absorber (WA) that has been extensively studied in the X-ray band. High-resolution spectra from 2000-2001 revealed a complex outflow with multiple ionization and velocity components. Two decades later, new XMM-Newton and XRISM observations allow us to investigate the long-term evolution of these outflows. We perform joint spectral modeling of the XMM-Newton/RGS and XRISM/Resolve time-averaged spectra using the pion photoionization code within SPEX. We derive the ionization parameter, column density, turbulent velocity, and outflow velocity for each absorption component, and investigate their thermal stability and Absorption Measure Distribution (AMD) to characterize the physical and dynamical properties of the WA in NGC 3783 in 2024. We compare these results with the 2000-2001 epoch to assess long-term variability, stability, and possible changes in the absorber population. We identify eight WA components spanning log $ξ=$ 1.08-3.38 and outflow velocities of 480-1230 km s$^{-1}$. The ranges of column densities and turbulent velocities remain broadly consistent with the WAs from 2000-2001, but the earlier data contained more low-ionization, high-velocity components. The total column density in 2024 is 1.5 times larger than in 2000-2001, requiring replenishment by fresh material. The dominant Unresolved Transition Array (UTA) absorber (Comp. B3) has increased its column density by a factor of three while maintaining a similar ionization parameter. The WAs in NGC 3783 have undergone significant structural and dynamical evolution over the past 24 years.
[abstract 39 / 41] (score: 2) - Title: Turbulent mixing of a hydrogen JET in crossflow: direct numerical simulation and model assessmentAuthors: Yiqing Wang, Chao Xu, Riccardo Scarcelli, Ben Cantrell, Jon Anders, Sameera Wijeyakulasuriya,Comments:Subjects: physics.flu-dynCreated: 2026-04-23; Updated: 2026-04-24; Datestamp: 2026-04-24
A numerical study for a hydrogen (H2) JET in an air crossflow (JICF) was performed using direct numerical simulation (DNS), large eddy simulation (LES), and Reynolds-averaged Navier-Stokes (RANS) approaches, based on a geometry representative of key aspects of port fuel injection (PFI) in a H2-fueled heavy-duty internal combustion engine. The focus was placed on the H2 mixing process and the turbulent species flux model used in the latter two approaches. Based on the DNS data, the performance of LES and RANS on predicting the turbulent flow fields and mixing process was comprehensively evaluated. Results showed that LES performs very well in predicting both the mean velocity and the Reynolds stress. In contrast, RANS significantly under-predicts all Reynolds stress components, while predicting the mean flow field relatively well. Regarding the H2 mixing prediction, LES shows an excellent agreement with DNS, while RANS significantly under-predicts the mixing process. The underlying reasons for the poor performance of RANS were identified by extracting turbulent transport properties used in RANS approach from DNS data. It was found that the turbulent diffusivity used in RANS is much smaller than that derived from DNS, which is attributed to the over-prediction on turbulent Schmidt number (Sct), as well as the under-prediction on turbulent viscosity. By further analyzing the anisotropic components of Sct and the misalignment angle between turbulent species fluxes directly obtained from DNS and those predicted by the RANS mixing model, the commonly used assumption of isotropic turbulent diffusivity in RANS was demonstrated to be invalid for the present configuration. This study provided a unique DNS dataset for H2 JET in a crossflow relevant to H2 PFI engines and generated new insights on improved modeling of turbulent mixing.
[abstract 40 / 41] (score: 2) - Title: Quark and gluon production in the presence of the time-varying chiral MAGNETic currentAuthors: Kirill Tuchin,Comments: 13 pages, 4 figuresSubjects: hep-ph nucl-thCreated: 2026-04-23; Updated: 2026-04-24; Datestamp: 2026-04-24
The chiral MAGNETic effect consists in the induction of the electric current along the direction of the MAGNETic field. The corresponding transport coefficient $b_0$, known as the chiral MAGNETic conductivity, is proportional to the chiral imbalance in the medium. In many systems, such as QUARK-gluon plasma, $b_0$ is time-dependent. This paper studies the effect of the time variation of $b_0$ on the particle spectra and energy loss produced through the chiral Cherenkov and associated processes in Abelian and non-Abelian systems. The rates of all processes are derived in the ultra-RELATIVISTIC approximation. The results are applied to the RELATIVISTIC heavy-ion collisions utilizing a specific model describing the relaxation of the initial $P$-odd domain within the QUARK-gluon plasma. The corresponding energy loss is computed. The results suggest strong POLARIZATION of JETs in QUARK-gluon plasma.
[abstract 41 / 41] (score: 2) - Title: The Dyson Minds 2025 Workshop: SETI around Black HolesAuthors: Olivia Curtis, Van Hunter Adams, Daniel Angerhausen, Joseph Bates, Anamaria Berea, Steven J. Dick, Martin Elvis, Sunil P. Khatri, Richard Linares, Manushaqe Muco, S. Seager, Jason T. Wright,Comments: Published in PASP, 14 pagesSubjects: astro-ph.GACreated: 2026-04-23; Updated: 2026-04-24; Datestamp: 2026-04-24
The Dyson Minds 2025 Workshop, held at the Center for Brains, Minds & Machines at MIT and organized by Penn State, MIT, and The Ultraintelligence Foundation, brought together researchers in astrophysics, engineering, artificial intelligence, computer science, and philosophy to examine "Dyson Minds" -- large-scale post-biological intelligences powered by energy harvested from supermassive BLACK HOLEs (SMBHs). Building on the ideas of F. J. Dyson (1960, 1966) and I. J. Good (1966), participants explored the physical, engineering, behavioral, and observational consequences of civilizations embodied as machinery operating near the universe's most powerful energy sources. The workshop aimed to develop new observational strategies capable of detecting signatures of such systems. Despite the highly cross-disciplinary scope, discussions centered on how a Dyson Mind might be constructed, how it might behave, and how those factors would shape strategies for the search for extraterrestrial intelligence. Key themes included the thermodynamic, mechanical, and stability limits of Dyson swarms; the trade-offs between power availability and communication latency in distributed minds; and how observability changes depending on whether Dyson Minds act as coherent entities or as loosely coordinated collectives. Across these topics, the consensus was that details of architecture and behavior strongly influence observational signatures. A major recommendation was to apply anomaly-detection methods to archival datasets, including those from WISE, JWST, and the Event Horizon Telescope, to identify unusual sources potentially overlooked by standard reduction pipelines. By integrating insights from multiple disciplines, the meeting advanced concrete, observation-focused strategies for future technosignature searches around SMBHs.
arXiv:2502.17689 [pdf, ps, other]
arXiv:2604.20095 [pdf, ps, other]
arXiv:2604.21390 [pdf, ps, other]
arXiv:2604.20963 [pdf, ps, other]
arXiv:2601.13312 [pdf, ps, other]
arXiv:2604.21405 [pdf, ps, other]
arXiv:2604.21624 [pdf, ps, other]
arXiv:2604.21639 [pdf, ps, other]
arXiv:2604.20950 [pdf, ps, other]
arXiv:2604.20953 [pdf, ps, other]
arXiv:2604.20971 [pdf, ps, other]
arXiv:2604.20975 [pdf, ps, other]
arXiv:2604.21439 [pdf, ps, other]
arXiv:2604.21497 [pdf, ps, other]
arXiv:2604.21557 [pdf, ps, other]
arXiv:2604.21666 [pdf, ps, other]
arXiv:2604.21759 [pdf, ps, other]
arXiv:2604.21856 [pdf, ps, other]
arXiv:2601.18422 [pdf, ps, other]
arXiv:2601.22490 [pdf, ps, other]
arXiv:2602.11736 [pdf, ps, other]
arXiv:2602.12496 [pdf, ps, other]
arXiv:2604.14225 [pdf, ps, other]
arXiv:2604.20609 [pdf, ps, other]
arXiv:2604.20941 [pdf, ps, other]
arXiv:2604.21000 [pdf, ps, other]
arXiv:2604.21013 [pdf, ps, other]
arXiv:2604.21099 [pdf, ps, other]
arXiv:2604.21128 [pdf, ps, other]
arXiv:2604.21136 [pdf, ps, other]
arXiv:2604.21149 [pdf, ps, other]
arXiv:2604.21180 [pdf, ps, other]
arXiv:2604.21224 [pdf, ps, other]
arXiv:2604.21419 [pdf, ps, other]
arXiv:2604.21520 [pdf, ps, other]
arXiv:2604.21622 [pdf, ps, other]
arXiv:2604.21642 [pdf, ps, other]
arXiv:2604.21710 [pdf, ps, other]
arXiv:2604.21797 [pdf, ps, other]
arXiv:2604.21872 [pdf, ps, other]
arXiv:2604.21886 [pdf, ps, other]