Current date: 2026-05-21

Setting default datestamp limit: 0

Datestamp limit: 2026-05-21 (0 days ago)

Created/updated limit: 2026-05-14 (7 days ago)

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=2026-05-21&until=2026-05-21&set=physics&metadataPrefix=arXiv

Scoring abstracts

Number of records retrieved: 683

Keyword score statistics

score 13 -- 1 abstracts

score 10 -- 1 abstracts

score 8 -- 2 abstracts

score 6 -- 2 abstracts

score 5 -- 1 abstracts

score 4 -- 3 abstracts

score 3 -- 9 abstracts

score 2 -- 18 abstracts

in total -- 37 abstracts

Articles that appeared on 2026-05-21

[abstract 1 / 37] Wow! (score: 13)
arXiv:2605.20843 [pdf, ps, other]

Title: Characterizing the origins of gamma-ray variability of the JETted ACTIVE GALACTIC NUCLEi observed with the FERMI-LAT

Authors: Yongyun Chen, Qiusheng Gu, Junhui Fan, Dingrong Xiong, Xiaoling Yu, Xiaogu Zhong, Xiaotong Guo, Nan Ding,

Comments: 19 pages, 7 figures, accept for publication in the Astrophysical Journal Supplement

Subjects: astro-ph.HE astro-ph.GA

Created: 2026-05-20; Updated: 2026-05-21; Datestamp: 2026-05-21

We conducted an analysis of gamma-ray variability in a large sample of JETted ACTIVE GALACTIC NUCLEi (AGNs) by utilizing archival FERMI-LAT light curves and applying damped random walk modeling to obtain variability amplitude. Our primary findings are summarized as follows: (1) The mean variability damping timescales of our sources are approximately 100 days. This damping timescale may imply that the diffusive shock acceleration plays an important role in the variability of gamma-ray emission. (2) Flat-spectrum radio QUASARs (FSRQs) demonstrate greater variability amplitude compared to BL Lacertae objects (BL Lacs). (3) The ratio of the distance of the emission region from the central supermassive BLACK HOLE to the dusty torus radius for our sources is $R\approx2-4.5R_{\rm DT}$. In contrast, the ratio of the distance of the emission region from the central supermassive BLACK HOLE to the BLR radius for our sources is $R\approx135-295R_{\rm BLR-in}$ and $R\approx123-270R_{\rm BLR-out}$. These findings indicate that the $γ$-ray emission region in JETted AGNs is likely located beyond the BLR, potentially could be associated with the dusty torus. (4) A statistical correlation is observed between variability amplitude and radio luminosity, radio loudness, X-ray luminosity, X-ray loudness, gamma-ray luminosity, and gamma-ray loudness, indicating a potential relationship between gamma-ray variability and JET activity. (5) Variability amplitude also shows a statistical correlations with SYNCHROTRON peak frequency luminosity, inverse Compton peak frequency luminosity, and Compton dominance. (6) Variability amplitude also correlates with BLACK HOLE mass, accretion disk luminosity, and Eddington ratio, implying that the accretion disk may also contribute to gamma-ray variability.

[abstract 2 / 37] Wow! (score: 10)
arXiv:2605.20632 [pdf, ps, other]

Title: Multi-wavelength Emission for a Post-merger Magnetar: The Magnetar-Driven Poynting Jet and Its Associated Pulsar Wind Nebula

Authors: Yun-Peng Li, Da-Bin Lin, Ning-Yuan Zhang, En-Wei Liang,

Comments: Accepted by ApJ

Subjects: astro-ph.HE

Created: 2026-05-20; Updated: 2026-05-21; Datestamp: 2026-05-21

A newborn, rapidly rotating MAGNETar may form in a binary neutron star merger and drive a Poynting-flux-dominated RELATIVISTIC JET. As the JET propagates outward, a forward shock (FS) and a reverse shock (RS) are formed, inflating a pulsar wind nebula (PWN) between them. We present a systematic study of the emission from both the PWN and the JET, whose MAGNETic energy is subject to dissipation. By following the dynamics of the JET-ejecta-PWN system, we find that, in most cases, the RS is long-lived: it first lags behind the contact discontinuity and eventually coincides with both the contact discontinuity and the FS after the JET breakout into the external medium. As a result, the emission exhibits a characteristic temporal evolution. Depending on the optical depth, the emission is initially dominated by thermal radiation from the optically thick ejecta, then by a JET-powered X-ray plateau once the system becomes optically thin, and finally by SYNCHROTRON and inverse-Compton radiation from the PWN FS at late times. In particular, external inverse-Compton scattering of JET photons by the FS naturally produces a late-time GeV bump together with a substantial TeV component. Our model can simultaneously account for early thermal emission, X-ray plateaus, and late-time GeV excesses in merger-driven GAMMA-RAY BURSTs, and also indicates that post-merger MAGNETar-driven PWNs are potential TeV photon sources.

[abstract 3 / 37] Wow! (score: 8)
arXiv:2508.00976 [pdf, ps, other]

Title: A Census of Variable Radio Sources at $3\,$GHz

Authors: Yjan A. Gordon, Peter S. Ferguson, Michael N. Martinez, Eric J. Hooper,

Comments: 25 pages, 20 Figures, 5 Tables. Published in OJAp. Supplementary data available at https://zenodo.org/records/18010746

Subjects: astro-ph.GA astro-ph.HE

Created: 2026-05-19; Updated: 2026-05-21; Datestamp: 2026-05-21

A wide range of phenomena, from explosive transients to ACTIVE GALACTIC NUCLEi, exhibit variability at radio wavelengths on timescales of a few years. Characterizing the rate and scale of variability in the radio sky can provide keen insights into dynamic processes in the Universe, such as accretion mechanics, JET propagation, and stellar evolution. We use data from the first two epochs of the Very Large Array Sky Survey (VLASS) to conduct a census of the variable radio sky. Approximately $3,600$ compact sources are found to significantly vary in brightness during the $\sim2.5\,$ years between observations. In this work we focus on sources that are detected in both VLASS epochs, but estimate there may be $>10,000$ additional variable radio sources in VLASS that are only detected in either the first or second epoch. For objects detected in both epochs whose mean flux density across the two epochs, $μ_{S}$, is brighter than $20\,$mJy, $5\,$% show brightness variations $>30\,$%, rising to $9\,$% at $μ_{S}>300\,$mJy. We analyze the redshift distributions, infrared colors, and $γ$-ray properties of the variable radio sources, finding that most have multiwavelength characteristics that are consistent with BLAZARs and QUASARs. Blazars in particular are found to be overrepresented among the variable radio sources, and the largest absolute changes in flux density are produced by BLAZARs. The largest fractional changes in brightness are exhibited by galactic sources. We discuss our results, including some of the more interesting and extreme examples of variable radio sources identified, as well as future research directions.

[abstract 4 / 37] Wow! (score: 8)
arXiv:2605.21320 [pdf, ps, other]

Title: FR0 RADIO GALAXy JETs -- I. linking JET dynamics and high-energy emission in LEDA 55267 and LEDA 58287

Authors: André F. S. Cardoso, Rita C. Anjos,

Comments: Accepted for publication in MNRAS

Subjects: astro-ph.HE astro-ph.GA

Created: 2026-05-20; Updated: 2026-05-21; Datestamp: 2026-05-21

Fanaroff-Riley type 0 (FR0) RADIO GALAXies host anomalously compact JETs whose disruption mechanism and high-energy emission remain poorly understood. We combine three-dimensional RELATIVISTIC hydrodynamical (RHD) simulations with broadband spectral energy distribution (SED) modeling from radio to TeV energies, focusing on LEDA~55267 and LEDA~58287. Our simulations show that recollimation shocks trigger hydrodynamical instabilities that drive turbulence and rapid deceleration, preventing the JETs from propagating beyond a few tens of parsecs and reproducing the observed compact radio morphology. Leptonic SED models adequately describe the observed emission up to GeV energies, but when simulated CTAO observations are included, statistical model comparison indicates strong evidence in favor of lepto-hadronic scenarios at TeV energies for both sources, a result that should be interpreted as a theoretical prediction to be tested by future observations. A leptonic analysis of the simulations reveals MAGNETized emitting regions with plasma beta parameters $β_{\rm p} \sim 10^{-5}$-$10^{-3}$, orders of magnitude below values reported for extended FRI JETs, consistent with JETs retaining the MAGNETization inherited from the launching region and providing a natural physical link between the compact JET dynamics and the lepto-hadronic emission.

[abstract 5 / 37] Yes (score: 6)
arXiv:2511.08684 [pdf, ps, other]

Title: Radiation-mediated shocks in GAMMA-RAY BURSTs: spectral evolution

Authors: Filip Alamaa, Frédéric Daigne,

Comments: Updated to match published version in A&A. Discussion regarding the light curve expanded. Main results are unchanged. Abstract slightly shortened due to arXiv character limit

Subjects: astro-ph.HE

Created: 2026-05-20; Updated: 2026-05-21; Datestamp: 2026-05-21

Radiation-mediated shocks (RMSs) occurring below the photosphere in a GAMMA-RAY BURST (GRB) JET could play a crucial role in shaping the prompt emission. In this paper, we study the time-resolved signal expected from such early shocks. We model an internal collision using a 1D special RELATIVISTIC hydrodynamical simulation, and we follow the photon distributions in the resulting forward and reverse shocks as well as in the common downstream region to well above the photosphere using a designated RMS simulation code. We compute the light curve and time-resolved spectrum of the resulting single pulse taking into account the emission at different optical depths and angles to the line of sight. For the specific case considered, we find a light curve consisting of a short pulse lasting $\sim 0.1~$s for an assumed redshift of $z = 1$, which could constitute a whole short GRB or be a building block within a highly variable longer GRB light curve. The efficiency is large, with $\approx 23$% of the total burst energy being radiated. The spectrum has a complex shape at very early times, after which it settles into a more generic shape with a smooth curvature below the peak energy, $E_p$, and a clear high-energy power law that cuts off at $\sim 5~$MeV in the observer frame. The spectrum becomes narrower and softer at late times with $E_p$ steadily decreasing during the pulse decay from $E_p \approx 250~$keV to $E_p \approx 100~$keV. The low-energy index, $α$, decreases during the bright part of the pulse from $α\approx -0.5$ to $α\approx -1$, although the low-energy part is better fit with a broken power law when the signal-to-noise ratio is high. The high-energy power law is generated by the reverse shock at low optical depths ($τ< 30$) and has an index that decreases from $β\approx -2$ to $β\approx -2.4$.

[abstract 6 / 37] Yes (score: 6)
arXiv:2605.20318 [pdf, ps, other]

Title: Guide-Field-mediated Multiscale Instabilities in Relativistic Reconnection

Authors: Pranab J Deka, Fabio Bacchini, Muni Zhou, Camille Granier,

Comments:

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

Created: 2026-05-19; Updated: 2026-05-21; Datestamp: 2026-05-21

We investigate MAGNETic-energy dissipation, current-sheet dynamics, and nonthermal particle acceleration in three-dimensional RELATIVISTIC RECONNECTion in an electron--ion plasma with a realistic mass ratio. Using particle-in-cell simulations of a double Harris current sheet, we explore a range of ion MAGNETisations and guide-field strengths to determine how guide fields regulate the overall MAGNETic energy dissipation. At low MAGNETisation, $σ_i=0.1$, increasing the guide field suppresses RECONNECTion: MAGNETic-energy dissipation decreases, the growth of tearing modes is weakened, and nonthermal particle acceleration remains inefficient. At higher MAGNETisations, $σ_i=1$ and $σ_i=5$, the behaviour changes qualitatively. In the zero-guide-field case, strong drift-kink activity corrugates and broadens the current sheet, inhibiting efficient tearing-mediated RECONNECTion. A weak guide field suppresses this drift-kink-driven disruption, allowing the current sheet to remain laminar and more coherent and thereby enhancing MAGNETic-energy dissipation. However, once the guide field becomes too strong, RECONNECTion is again suppressed: the onset is delayed, tearing activity weakens, current-sheet compression is reduced, and the system retains a larger fraction of its initial MAGNETic energy. This non-monotonic behaviour is reflected consistently in MAGNETic-energy evolution, Fourier analysis of the tearing and kink modes, current-sheet thickness, and nonthermal particle acceleration. The most dissipative cases are not necessarily the zero-guide-field runs, but rather those in which the guide field balances drift-kink suppression without strongly impeding the tearing modes. Our results show that the overall system evolution is controlled not only by the available MAGNETic energy, but also by the guide-field-regulated morphology and stability of the RECONNECTing current sheet.

[abstract 7 / 37] Yes (score: 5)
arXiv:2605.19473 [pdf, ps, other]

Title: Radio-X-ray Time Lags in GX 339-4: Probing Magnetic Field Transport in Black Hole Accretion

Authors: Dizhan Du, Bei You, Zhen Yan, Yuao Ma, Xinwu Cao,

Comments: 13 pages, 7 figures, submitted to APJ

Subjects: astro-ph.HE

Created: 2026-05-20; Updated: 2026-05-21; Datestamp: 2026-05-21

We present an analysis of the time delay between the radio emission and the X-ray Compton luminosity during the 2010-2011 outburst of GX 339-4. Using the interpolated cross-correlation function (ICCF), we measure the time delay between the Compton luminosity and the radio luminosity, and find that during the rising hard state, the radio emission precedes the Compton luminosity by approximately 3 days. In contrast, in the decaying hard state, the radio emission lags behind the Compton luminosity by about 8 days. By estimating the mass accretion rate and the disk truncation radius, the calculated inner MAGNETic field can account for both the radio delay in the decaying hard state and the radio precedence in the rising hard state. The time delays observed in different outbursts across multiple sources are compared further, and the underlying physical mechanisms account for this difference are discussed. These results provide insights into the evolving coupling between the inner accretion flow and the JET in BLACK HOLE X-ray binaries.

[abstract 8 / 37] Yes (score: 4)
arXiv:2511.20682 [pdf, ps, other]

Title: High-energy radiation from the pulsar Equatorial Current Sheet

Authors: Ioannis Contopoulos, Jerome Petri, Ioannis Dimitropoulos,

Comments: 9 pages, 5 figures, Astronomy and Astrophysics (in press)

Subjects: astro-ph.HE

Created: 2026-05-20; Updated: 2026-05-21; Datestamp: 2026-05-21

Pulsars emit beams of radiation that reveal the extreme physics of neutron star MAGNETospheres. Yet, their understanding remains incomplete. Recent global Particle-in-Cell (PIC) simulations have raised several questions that led us to question their validity and their extrapolation to realistic particle Lorentz factors, electric and MAGNETic fields. We want to generate realistic sky maps of high-energy radiation from first principles. We propose a novel method to study the Equatorial Current Sheet (ECS) where most of the particle acceleration and the high-energy radiation is expected to originate. We first determine its shape and external MAGNETic field with a steady-state ideal force-free solution. Then, we consider the extra electric and MAGNETic field components that develop when dissipation is considered. Finally, we study the particle acceleration and radiation that is due to these extra field components for realistic field and particle parameters. We generate realistic sky maps of high-energy radiation and compare them with those obtained via PIC simulations. These sky maps may also be closely reproduced using the ECS of the split-monopole solution beyond the light cylinder. The ECS is probably stabilized by the normal MAGNETic field component that is due to the global MAGNETospheric RECONNECTion. Our method helps us better understand the origin of the pulsed high-energy radiation in the pulsar MAGNETosphere.

[abstract 9 / 37] Yes (score: 4)
arXiv:2605.20317 [pdf, ps, other]

Title: Simulation-Based Prediction of Black Hole Fe K$α$ Line Profiles

Authors: Chris Nagele, Julian H. Krolik, Brooks E. Kinch, Jeremy D. Schnittman,

Comments: Accepted to ApJ

Subjects: astro-ph.HE

Created: 2026-05-19; Updated: 2026-05-21; Datestamp: 2026-05-21

One of the most useful spectral diagnostics of accreting BLACK HOLE systems is the Fe K$α$ fluorescence line. Detected in many systems, it is often used to estimate the BLACK HOLE spin, as its breadth is attributed to RELATIVISTIC kinematics near the spin-dependent innermost stable circular orbit (ISCO). In a companion paper, we showed how continuum spectra emitted by accreting BLACK HOLEs can be derived from snapshots of general RELATIVISTIC MAGNETohydrodynamics simulations by combining radiation transfer solutions for the disk body and the corona. In this paper, we focus on the Fe K$α$ line, solving its transfer problem on the basis of local ionization and thermal balance. Its equivalent width is $\sim 25-225$ eV, depending mainly on viewing angle, for an accretion rate of 1$\%$ Eddington. Contrary to common assumptions, the illuminating X-ray spectrum and ionization parameter $ξ$ can be strong functions of radius; e.g. $ξ\propto r^{-1.5}$ in this simulation. Consequently, the region of the disk near the ISCO is completely ionized and contributes almost no Fe K$α$ photons; most of the flux is made at radii $\gtrsim 10 r_g$. The lines are broadened by a combination of RELATIVISTIC Doppler shifts, Compton broadening in the disk atmosphere, and the differing line energies emitted by different Fe ions. These new mechanisms expand the parameter space of acceptable models, including the possibility of broad line profiles without large BLACK HOLE spin; physical trends revealed by the simulations can refocus fitting efforts on the most relevant sections of the parameter space.

[abstract 10 / 37] Yes (score: 4)
arXiv:2605.20779 [pdf, ps, other]

Title: A MINOT-based Study of Gamma-ray emission from SPT-CL J2012-5649/Abell 3667

Authors: Siddhant Manna, Shantanu Desai,

Comments: 22 pages, 13 Figures

Subjects: astro-ph.HE

Created: 2026-05-20; Updated: 2026-05-21; Datestamp: 2026-05-21

We present an analysis of the non-thermal properties of the merging galaxy cluster SPT-CL J2012-5649/Abell~3667 ($z = 0.0556$, $M_{500} = 7.16 \times 10^{14}\ M_\odot$) using the MINOT non-thermal emission modelling framework. The predicted hadronic gamma-ray flux from $pp$ interactions in the $1$--$300\ \mathrm{GeV}$ band is $2.82 \times 10^{-11}\ \mathrm{cm^{-2}\ s^{-1}}$ within $R_{500}$, rising to $1.15 \times 10^{-10}\ \mathrm{cm^{-2}\ s^{-1}}$ at the truncation radius ($3.7\,R_{500}$), in order-of-magnitude agreement with the FERMI-LAT reported flux of $1.3 \times 10^{-10}\ \mathrm{cm^{-2}\ s^{-1}}$. Approximately $76\%$ of the predicted hadronic flux originates from beyond $R_{500}$. The IC contribution from cosmic-ray electrons is subdominant relative to the hadronic $π^0$-decay gamma-ray component by a factor of ${\sim}20$ in the $1$--$300\ \mathrm{GeV}$ energy band, and therefore does not contribute significantly to the observable signal. Although the expected hadronic flux is in approximate agreement with the observed FERMI-LAT flux level in the $1$--$300\ \mathrm{GeV}$ band, the observed spectral index ($Γ= -3.61 \pm 0.33$) is in tension with the hadronic prediction ($Γ\approx -2.4$ to $-2.6$).

[abstract 11 / 37] (score: 3)
arXiv:2506.16676 [pdf, ps, other]

Title: Fast solvers for Tokamak fluid models with PETSC

Authors: Mark F. Adams, Jin Chen, Benjamin Sturdevant,

Comments:

Subjects: physics.plasm-ph cs.PF

Created: 2026-05-20; Updated: 2026-05-21; Datestamp: 2026-05-21

Multigrid (MG) is widely recognized as a highly effective solver for the model problem, the Laplacian, but textbook MG fails on most problems of interest. MG methods have been applied to complex, real-world applications with careful consideration of the physical model and discretization. This work develops the first step in applying MG methods to science and engineering relevant MAGNETohydrodynamics (MHD) tokamak models in the \textit{M3D-C1} https://m3dc1.pppl.gov fusion energy science code. The semi-implicit time integrator in \textit{M3D-C1} is composed of many linear solves. The implicit advance of the momentum equation is the most challenging and is the focus of this work. The current production solver in \textit{M3D-C1} is a block Jacobi (BJ) preconditioner within a Krylov solver, where blocks group degrees of freedom on planes of constant toroidal coordinate. BJ convergence degrades as the number of planes increases due to the spectral properties of the matrix preconditioned with BJ. The partially MAGNETic field-aligned, regular toroidal grid structure in \textit{M3D-C1} is amenable to semi-coarsening geometric MG in the toroidal direction. This paper develops such a solver and demonstrates competitive performance on a runaway electron model of a SPARC https://cfs.energy/technology/sparc disruption, and superior robustness on a stellarator model on which the BJ solver fails to converge.

[abstract 12 / 37] (score: 3)
arXiv:2511.09659 [pdf, ps, other]

Title: Finite Populations & Finite Time: The Non-Gaussianity of a Gravitational Wave Background

Authors: William G. Lamb, Jeremy M. Wachter, Andrea Mitridate, Shashwat C. Sardesai, Bence Bécsy, Emily L. Hagen, Stephen R. Taylor, Luke Zoltan Kelley,

Comments: 20 pages, 8 figures. Accepted by Phys. Rev. D. Version 3 - increased model complexity with addition of inclination and polarisation angle. References updated. Results updated but conclusions unchanged

Subjects: gr-qc astro-ph.HE

Created: 2026-05-19; Updated: 2026-05-21; Datestamp: 2026-05-21

Strong evidence for an isotropic, Gaussian gravitational wave background (GWB) has been found by multiple pulsar timing arrays (PTAs). The GWB is expected to be sourced by a finite population of supermassive BLACK HOLE binaries (SMBHBs) emitting in the PTA sensitivity band, and astrophysical inference of PTA data sets suggests a GWB signal that is at the higher end of GWB spectral amplitude estimates. However, current inference analyses make simplifying assumptions, such as modeling the GWB as Gaussian, assuming that all SMBHBs only emit at frequencies that are integer multiples of the total observing time, and ignoring the interference between the signals of different SMBHBs. In this paper, we build analytical and numerical models of an astrophysical GWB from circular, inspiralling binaries inclined relative to the line-of-sight of the observer, without the above approximations, and compare the statistical properties of its induced PTA signal to those of a signal produced by a Gaussian GWB. We show that finite population and windowing effects introduce non-Gaussianities in the PTA signal, which are currently unmodeled in PTA analyses.

[abstract 13 / 37] (score: 3)
arXiv:2602.16214 [pdf, ps, other]

Title: Cosmic-Ray Spectra and Metal Budget Regulated by the Galactic Wind

Authors: Yusaku Fukumoto, Katsuaki Asano, Jiro Shimoda,

Comments: 13 pages, 10 figures

Subjects: astro-ph.HE astro-ph.GA

Created: 2026-05-20; Updated: 2026-05-21; Datestamp: 2026-05-21

We study the advection effect of the Galactic wind on the local COSMIC RAY spectra. The spectral hardening from a few hundred GV and softening from a few TV are reproduced by a velocity profile with a maximum velocity of $\sim 700~\mbox{km}~ \mbox{s}^{-1}$ without introducing a break in the power-law dependence of the diffusion coefficient. Additionally, we find that a hard CR spectrum below $\sim$ TV with an index of $\sim 2$ at an altitude $\sim 3$-$5$ kpc from the Galactic disk. This hard spectrum is favorable for the gamma-ray spectrum of the FERMI bubbles. With the obtained CR fluxes, we discuss the matter circulation in our Galaxy with the wind. While the wind has an essential role in maintaining the metal abundance in the disk, the production rate of Beryllium, which originates from CR spallation, is so low that the ratio Be/O in the halo should be larger than that in the disk gas.

[abstract 14 / 37] (score: 3)
arXiv:2605.20327 [pdf, ps, other]

Title: On the origin of anomalous dissipation in simulations of tidal disruption events

Authors: Chris Nixon, Eric R. Coughlin, Zachary L. Andalman,

Comments: 22 pages, 13 figures, 1 appendix, submitted

Subjects: astro-ph.HE astro-ph.GA astro-ph.SR physics.comp-ph

Created: 2026-05-19; Updated: 2026-05-21; Datestamp: 2026-05-21

In a tidal disruption event (TDE), a star is destroyed by the tidal field of a supermassive BLACK HOLE. The stellar debris is initially placed on highly elliptical orbits, and a longstanding question in TDE theory is: How does the stellar debris circularize into a disc and accrete? The originally proposed answer to this question is self-intersection shocks, where RELATIVISTIC apsidal precession results in a strong collision between the incoming and outgoing material. However, global simulations of TDEs tend to find enhanced hydrodynamical dissipation prior to any intersections of the debris orbits, with the material ``fanning out'' into a wide-angle and partially-unbound outflow upon passing through pericenter. We show that this dissipation is numerical in origin and arises from a combination of 1) the change in the kinematics of the debris as it passes through pericenter, with its velocity profile along the stream transitioning from strongly diverging pre-pericenter to strongly converging post-pericenter, and 2) the dependence of numerical algorithms (viscosity switches for particle-based methods and Riemann solvers for Godunov-based schemes) on the diverging vs. converging nature of the fluid. We support this conclusion with analytical and numerical modeling. We discuss possible resolutions to these issues as well as the implications of our findings in the context of observations.

[abstract 15 / 37] (score: 3)
arXiv:2605.20698 [pdf, ps, other]

Title: CO(7-6) and [C I](2-1) survey in z > 6 QUASARs

Authors: Fuxiang Xu, Roberto Decarli, Ran Wang, Anna Elisabetta Borea, Antonio Pensabene, Xiaohui Fan, Dominik Riechers, Eduardo Bañados, Axel Weiß, Michele Costa, Fabian Walter, Feige Wang, Jinyi Yang, Bram Venemans, Jianan Li, Emanuele Paolo Farina,

Comments: 21 pages, 18 figures, accepted for publication in A&A

Subjects: astro-ph.GA

Created: 2026-05-20; Updated: 2026-05-21; Datestamp: 2026-05-21

High-redshift ($z\gtrsim6$) QUASARs trace the earliest supermassive BLACK HOLEs and intense STAR FORMATION, offering key laboratories for BLACK HOLE-galaxy evolution at cosmic dawn. While far-infrared studies have revealed large dust reservoirs and strong [C II] emission, the physical conditions and molecular gas content of their ISM remain uncertain. We present ALMA Band 3 observations of the redshifted CO(7-6) and [C I](2-1) emission lines and dust continuum in a sample of 18 QUASARs at $z \sim 6$. We detected CO(7-6) in 15/18, [C I](2-1) in 6/18, and continuum in 13/18 sources. Line luminosities and continuum fluxes were used to estimate molecular gas masses from CO, [C I], and dust, and a hierarchical Bayesian cross-calibration of all four tracers yielded consistent per-source $M_{\rm H_2}$ estimates and conversion factors. Comparison with PDR and XDR model grids using the $L_{\rm [CII]}/L_{\rm [CI]}$ and $L_{\rm CO(7--6)}/L_{\rm TIR}$ ratios suggests gas densities of $n > 10^4$ cm$^{-3}$ and radiation fields of $G_0 \sim 10^3$--$10^4$ for sources consistent with PDR solutions, while many QUASARs fall outside the model parameter space. The $L'_{\rm CO(7-6)}/L'_{\rm [CI](2-1)}$ ratio indicates that a large fraction of the molecular gas resides in a warm and highly excited phase. Together these results suggest that classical PDR heating alone cannot explain the observed line ratios and that additional volumetric processes such as X-ray irradiation, turbulence and shocks, or enhanced cosmic-ray heating likely influence the excitation of the cold ISM. They demonstrate the power of multi-line diagnostics in revealing the excitation and structure of the cold ISM in early QUASAR host galaxies and highlight the need for joint analysis of CO, [C I], [C II], and dust emission to characterize STAR FORMATION and AGN-driven heating at cosmic dawn.

[abstract 16 / 37] (score: 3)
arXiv:2605.20881 [pdf, ps, other]

Title: Relativistic Scattering in the Funnel of Cygnus X-3

Authors: Suraj K. Chaurasia, Ranjeev Misra, Amit Pathak,

Comments: Accepted for publication in The Astrophysical Journal

Subjects: astro-ph.HE

Created: 2026-05-20; Updated: 2026-05-21; Datestamp: 2026-05-21

Cygnus X-3 presents significant challenges to standard accretion models. Recent polarimetric observations by IXPE reveal high POLARIZATION degrees (PD) in the hard state ($\sim 23\%$) and unexpectedly significant POLARIZATION in the soft state ($\sim 12\%$), which are difficult to reconcile with static scattering models at low inclination ($i \approx 30^\circ$). We present a RELATIVISTIC scattering model within a funnel-shaped geometry that resolves this discrepancy. We show that a single funnel-outflow configuration with variable bulk velocity $β$ can reproduce both POLARIZATION states, with lower velocities ($β\approx 0$) yielding $\sim 12\%$ POLARIZATION (soft state) and mildly RELATIVISTIC velocities ($β\lesssim 0.4$) producing $\sim 23\%$ POLARIZATION (hard state) at $i \approx 30^\circ$ for half funnel opening angles of $\sim 13^\circ$-$16^\circ$. Relativistic aberration modifies the effective scattering angle in the comoving frame, enhancing POLARIZATION in the hard state while recovering the static limit in the soft state. The model also yields a consistent estimate of the intrinsic luminosity, of order $\sim 10^{40}$ erg s$^{-1}$, supporting a super-Eddington interpretation. This framework provides a unified explanation of the observed POLARIZATION properties of Cygnus X-3.

[abstract 17 / 37] (score: 3)
arXiv:2605.21278 [pdf, ps, other]

Title: Chandra X-ray Observations of the Pulsar Wind Nebula within CTA 1

Authors: Seth Gagnon, Oleg Kargaltsev, Jason Alford, Joseph Gelfand, Alexander Lange,

Comments: Submitted to ApJ, 18 pages, 11 figures, 5 tables

Subjects: astro-ph.HE

Created: 2026-05-20; Updated: 2026-05-21; Datestamp: 2026-05-21

We present deep Chandra observations of the pulsar wind nebula (PWN) powered by PSR J0007+7303 in the composite SUPERNOVA remnant CTA 1. The merged ACIS image shows a $\sim20''$ JET extending south of the pulsar and bending toward the southwest, a faint counter-JET to the north, and a compact torus oriented approximately perpendicular to the JET axis. Using an archival observation from 2003 we perform relative astrometry over a $\sim20$ yr baseline and constrain the pulsar's transverse velocity to $\lesssim 200~\mathrm{km~s^{-1}}$ at the distance of 1.4 kpc at 95% confidence. Spatially resolved spectroscopy shows hard spectra for the JET and torus (photon indicies $Γ\approx 1.2-1.4$) and a softer spectrum for the extended nebula ($Γ= 1.85 \pm 0.11$), indicating minimal radiative cooling in the compact regions. Modeling of the torus, associated with the termination shock, as an inclined circle yields a viewing angle $ζ\approx 50^\circ$. The outer gap and two-pole caustic pulsar emission models then imply a moderate MAGNETic inclination ($α\sim 20^\circ$-$70^\circ$). Broadband spectral energy distribution (SED) modeling from radio to PeV $γ$-rays for a one-zone leptonic scenario yields a low MAGNETic field ($B \approx 1.4$-$3.2~μ\mathrm{G}$) and a high electron cutoff energy ($E_{\rm cut} \sim 0.2$-$0.3~\mathrm{PeV}$), indicating that the MAGNETic field decreases rapidly outside of the compact nebula. These results establish CTA 1 as a young, low X-ray efficiency PWN with a hard injection spectrum capable of accelerating particles to PeV energies.

[abstract 18 / 37] (score: 3)
arXiv:2605.21331 [pdf, ps, other]

Title: Searching for links between energetic millisecond pulsars and repeating fast radio bursts

Authors: R. J. van Ruiten, J. W. T. Hessels, S. Bhandari, P. Chawla, A. Gopinath, D. M. Hewitt, K. Nimmo, M. P. Snelders,

Comments: Published in MNRAS

Subjects: astro-ph.HE

Created: 2026-05-20; Updated: 2026-05-21; Datestamp: 2026-05-21

The unexpected localization of the repeating FRB 20200120E to a globular cluster challenges conventional FRB models based on MAGNETars formed via core collapse. One alternative model suggests that FRB 20200120E is a millisecond pulsar (MSP) producing giant pulses (GPs). To test this hypothesis, we compared the characteristics of FRB 20200120E bursts with the GPs of the most energetic Galactic MSP known, M28A (PSR B1821$-$24A), using observations with the Parkes (Murriyang) telescope's Ultra Wideband Low-frequency (UWL) receiver. Our analysis provides insight into the spectral structure and frequency extent of M28A's GPs, revealing broad-band spectra spanning $700-4000$ MHz (in some cases) with complex spectral peaks. We find that known M28A GP characteristics persist at this bandwidth, such as durations, luminosities, periodicity, wait-time, and energy distribution. A sub-band search for narrow-band GPs yielded no detection of genuinely narrow-band GPs. However, we do find narrow-band spectral peaks of $\sim100$ MHz bandwidth, a similar scale observed for FRB 20200120E's bursts. Compared to FRB 20200120E's bursts, M28A's GPs have $50\times$ shorter durations, $10^5\times$ lower spectral luminosities, clear periodicity (vs. no periodicity), a purely Poissonian wait-time distribution (vs. quasi-Poissonian), and generally broad-band spectra with narrow-band peaks (vs. only narrow-band bursts). Both sources show a steep energy distribution and minor dispersion measure variability. Our study finds no strong links between M28A and FRB 20200120E. However, we cannot rule out the possibility that FRB 20200120E is a rare and unique type of MSP with no Galactic analogue. Furthermore, higher-cadence monitoring of M28A, for hundreds to thousands of hours, might reveal rare but extremely luminous pulses.

[abstract 19 / 37] (score: 3)
arXiv:2605.21375 [pdf, ps, other]

Title: Compact Object Astrophysics with Frontline Astrometry

Authors: P. Gandhi,

Comments: Based on invited talk and proceedings for the ISSAC-2024 symposium, University of Delhi

Subjects: astro-ph.HE

Created: 2026-05-20; Updated: 2026-05-21; Datestamp: 2026-05-21

Astrometry - the precise measurement of celestial positions and motions - is entering the micro-arcsecond ($μ$as) era at multiple wavelengths, enabling new insights on compact objects across all mass scales. Here we review how high-precision astrometry is advancing our understanding of compact objects - neutron stars (NSs) and BLACK HOLEs (BHs). We provide the context for high precision astrometry before discussing natal kicks and the latest results from Gaia Data Release 3 (DR3). We highlight the evidence for mass-dependent peculiar velocities of accreting binaries, and also reveal a close similarity between NSs and BHs. Next-generation surveys will find recoiling supermassive BHs (SMBHs) in galactic nuclei, exploring how gravitational-wave-induced kicks operate. Exploitation of scientific opportunities on the lunar surface could facilitate much larger collecting areas and astrometric precision in X-rays than currently feasible.

[abstract 20 / 37] (score: 2)
arXiv:2509.16793 [pdf, ps, other]

Title: Galilean ElectroMAGNETic Particle-in-Cell Code

Authors: Alexander Pukhov, Nina Elkina, Tom Wilson,

Comments:

Subjects: physics.plasm-ph

Created: 2026-05-20; Updated: 2026-05-21; Datestamp: 2026-05-21

We introduce a Galilean electroMAGNETic particle-in-cell (GEM-PIC) algorithm, which transforms the full set of Maxwell equations and the Vlasov equation into the boosted coordinates. This approach preserves the electroMAGNETic structure of the interaction while exploiting scale separation for computational effi ciency. Unlike quasistatic methods, GEM-PIC does not have to distinguish between beam and streaming particles, allowing a self-consistent treatment of particle trapping. The EM-PIC algorithm allows for highly effi cient and accurate simulations of plasma-based wakefield acceleration.

[abstract 21 / 37] (score: 2)
arXiv:2512.10666 [pdf, ps, other]

Title: Can accreting isolated neutron stars be detected?

Authors: Marina Afonina, Anton Biryukov, Sergei Popov,

Comments: 26 pages, 5 figures, accepted to JHEAP

Subjects: astro-ph.HE

Created: 2026-05-20; Updated: 2026-05-21; Datestamp: 2026-05-21

We perform population synthesis modeling of isolated neutron stars in the Milky Way over its lifetime. Compared with previous studies, we use more detailed models of the interstellar medium and the MAGNETo-rotational evolution of neutron stars. We demonstrate that presently, the spin-down rate at the propeller stage is the main uncertain factor that influences the number of accreting isolated neutron stars. If the propeller stage duration allows neutron stars to begin accreting matter from the interstellar medium and if the efficiency of accretion is high, then the number of accreting isolated neutron stars in eROSITA data can reach ~a few thousand. Still, uncertainties in spin-down at the propeller stage and in the accretion process can drastically decrease this number. We suggest that future observations of neutron stars in wide low-mass binaries recently discovered by Gaia can clarify these issues.

[abstract 22 / 37] (score: 2)
arXiv:2602.06027 [pdf, ps, other]

Title: ACT DR6+Planck impact on inflation with non-zero vacuum expectation value and the post-inflationary behavior

Authors: F. B. M. dos Santos, J. G. Rodrigues, G. Rodrigues, C. Siqueira, J. S. Alcaniz,

Comments: 12 pages, 9 figures, 1 table. Figure 6 and equation 8 were updated, with minimal changes to the text

Subjects: astro-ph.CO

Created: 2026-05-19; Updated: 2026-05-21; Datestamp: 2026-05-21

The impact of the most recent cosmic microwave background (CMB) data from the Atacama Cosmology Telescope (ACT) is studied for a model of cosmic inflation which predicts a non-zero vacuum expectation value (VEV) $M$ for a large-field regime. Since lower values of $M$ are compatible with the higher spectral index $n_s$ provided by the ACT+Planck joint analysis, we establish new limits on this parameter while also considering further CMB data from the latest BICEP/Keck Array release for CMB POLARIZATION modes. We find $\log_{10}M/M_{Pl}=-2.5^{+1.1}_{-1.3}$ at 68\% confidence level, compatible with $M/M_{Pl}\simeq 0.003$, which is interesting for post-inflationary processes, such as preheating. We conduct a lattice simulation for the inflaton field for the first few e-folds, as the model is compatible with the production of relics such as oscillons, which are possible candidates as sources of gravitational waves and primordial BLACK HOLEs. We find that the model indeed produces localized, quasi-spherical structures compatible with oscillons, which might lead to signatures detectable by future experiments. However, in agreement with recent works, we find that although the abundance of gravitational waves that could be generated in this regime has an amplitude well within the sensitivities of these detectors, the frequency range is on the GHz limit, away from the expected frequencies. Finally, we estimate the impact of a coupling of the type $yϕχ^2$ to the inflaton, in the realization of perturbative reheating, directly impacting the predictions of the model, as lower values of $M$ are consistent with both the entire allowed temperature range, and the limits imposed by BICEP/Keck Array+Planck+ACT.

[abstract 23 / 37] (score: 2)
arXiv:2603.10461 [pdf, ps, other]

Title: Gauss-Bonnet scalarization of charged qOS-BLACK HOLEs

Authors: Hong Guo, Wontae Kim, Yun Soo Myung,

Comments: 24 pages, 11 figures

Subjects: gr-qc

Created: 2026-05-20; Updated: 2026-05-21; Datestamp: 2026-05-21

The Gauss-Bonnet (GB) scalarization for charged quantum Oppenheimer-Snyder (cqOS)-BLACK HOLEs is investigated in the Einstein-Gauss-Bonnet-scalar theory with the nonlinear electrodynamics (NED) term. Here, the scalar coupling function to GB term is given by $f(ϕ)=2λϕ^2$ with a coupling constant $λ$. Three parameters of mass ($M$), action parameter ($α$), and MAGNETic charge ($P$) are necessary to describe the cqOS-BLACK HOLE, and it may become the qOS-BLACK HOLE when $P=M$. The GB scalarization of cqOS-BLACK HOLEs comes into two cases GB$^\pm$, depending on the sign of GB term which triggers the different phenomena. For $α=0$ and $λ>0$, GB$^+$ scalarization is allowed, while for $α\not=0$ and $λ<0$, GB$^-$ scalarization appears for a narrow band of $3.5653\le α\le 4.6875$. After discussing the onset GB$^-$ scalarization, we construct scalarized cqOS-BLACK HOLEs which belong to the single branch. The scalar field decays much more rapidly compared to the GB$^+$ case. Stability analysis shows these scalarized BLACK HOLEs are linearly stable under scalar perturbations.

[abstract 24 / 37] (score: 2)
arXiv:2605.19348 [pdf, ps, other]

Title: Transition of vortex dipole dynamics in holographic superfluids

Authors: Yu-Kun Yan, Shanquan Lan, Yu Tian, Hongbao Zhang,

Comments: 6 pages, 4 figures, small modifications

Subjects: hep-th

Created: 2026-05-20; Updated: 2026-05-21; Datestamp: 2026-05-21

Using holographic duality, we reveal a transition in vortex dipole dynamics below a critical dipole size in strongly interacting superfluids, characterized by a significant suppression of mutual friction. In the bulk, this transition is triggered by a topological RECONNECTion of vortex tubes, which disconnects the boundary vortices from the BLACK HOLE horizon and forms a \textit{U-pipe}. Consequently, the post-transition evolution is governed by the contraction of the bulk \textit{U-pipe} rather than the mutual friction associated with the horizon, revealing a scale-dependent dissipation mechanism. We further show that this RECONNECTion persists over a broad temperature range, even when the transition becomes unobservable at high temperatures. Our results provide a dissipation-based interpretation for the anomalous critical dipole scale observed in strongly interacting cold-atom experiments, and suggest the existence of distinct dissipative regimes in strongly interacting superfluids.

[abstract 25 / 37] (score: 2)
arXiv:2605.20227 [pdf, ps, other]

Title: Cosmological perturbations with $f(R)$ gravity scalarons : Galaxy power spectra and the scalaron mass

Authors: Abhijit Talukdar, Sanjeev Kalita, Shadab Alam,

Comments: 22 pages, 9 figures, 1 table

Subjects: astro-ph.CO gr-qc

Created: 2026-05-15; Updated: 2026-05-21; Datestamp: 2026-05-21

In this paper we study cosmological perturbations with $f(R)$ gravity scalaron. We consider epoch of transition from early general relativity (GR) phase to late time non-GR phase of cosmogenic history for a viable $f(R)$ gravity Lagrangian close to the $Λ$CDM theory at early cosmic history. We study deviation in matter power spectra from $Λ$CDM scenario. Galaxy power spectra multipoles are generated using galaxy bias, velocity dispersion and modified gravity parameters. While monopole and quadrupole matter power in $f(R)$ theory increase towards larger $k$ (small scales), quadrupole power spectrum remains elevated relative to $Λ$CDM for smaller $k$ (large scales), upto $k\approx 0.02$. These power spectra provide observables for testing gravity through the current and future galaxy survey missions such as DESI, EUCLID, 4MOST and PFS. We report appropriate GR limit of scalaron mass in galactic and massive BLACK HOLE scales. Evolution of the scalaron mass and its general RELATIVISTIC limit for various cosmic structures are reported. Deviation from GR in cosmogenic evolution is attributed to decrease in scalaron mass with cosmic time.

[abstract 26 / 37] (score: 2)
arXiv:2605.20320 [pdf, ps, other]

Title: The third wheel: ringdown and lensing of triple systems

Authors: Vitor Cardoso, Giuseppe Ficarra, Jaime Redondo-Yuste, João Sieiro dos Santos,

Comments: 19 pages, 10 figures. Comments are welcome

Subjects: gr-qc astro-ph.HE

Created: 2026-05-19; Updated: 2026-05-21; Datestamp: 2026-05-21

Triple systems have progressively been recognized as ubiquitous in our universe and provide a good testing ground for wave generation and propagation in nontrivial environments. We study the dynamics of triple systems in a fully nonlinear setting. In particular, we analyze numerical relativity simulations of head-on collisions of BLACK HOLEs in the presence of a companion. We show evidence for Doppler and gravitational redshift in the ringdown, and clear signs of amplification by lensing. In certain cases, we also show the appearance of a second image, with hints of resonant mode excitation. Our results pave the way for the understanding of mergers in the vicinity of massive companions. Even in extreme setups we do not find collapse to BLACK HOLEs from lensed gravitational radiation.

[abstract 27 / 37] (score: 2)
arXiv:2605.20323 [pdf, ps, other]

Title: Suppression of Radiative Cooling in Galaxy Cluster Cores by the Combination of AGN Heating and Sloshing

Authors: Yutaka Fujita, Tomoaki Matsumoto, Keiichi Wada,

Comments: 9 pages, 6 figures

Subjects: astro-ph.GA

Created: 2026-05-19; Updated: 2026-05-21; Datestamp: 2026-05-21

Recent XRISM observations suggest that gas mixing induced by sloshing contributes to core heating. We systematically investigate the suppression of cooling flows in galaxy cluster cool cores through three-dimensional hydrodynamic simulations that incorporate both sloshing-driven turbulence and ACTIVE GALACTIC NUCLEus (AGN) heating. The AGN heating is modeled as thermal energy input that mimics cosmic-ray heating. Sloshing is represented by simple waves with amplitudes α= 0, 0.15, and 0.3 times the sound speed and wavelengths λ= 200, 1000, and 2000 kpc. We evolve each model from an isothermal initial condition to t = 8 Gyr. Without AGN heating, sloshing suppresses cooling, but it cannot stop it completely unless the core is fully disrupted. Longer wavelengths promote deeper mixing and greater suppression. Sloshing can cause cooler gas to move more quickly than hotter gas. This phenomenon has been observed in a few clusters by XRISM. When AGN heating is included, the dense central gas is heated efficiently, substantially delaying or preventing the onset of a cooling flow. However, for intermediate wave lengths, sloshing can displace the densest gas away from the AGN heating zone, reducing the feedback effect and paradoxically enhancing net cooling relative to the wave-free case. These results highlight a non-trivial coupling between sloshing and AGN feedback, with implications for interpreting XRISM velocity and temperature maps of cool-core clusters.

[abstract 28 / 37] (score: 2)
arXiv:2605.20335 [pdf, ps, other]

Title: Thermal Structure and Chemical Enrichment of the North and South Polar Spurs: Supersolar N/O and Ne/O in the X-ray Plasma

Authors: Anjali Gupta, Smita Mathur, Joshua Kingsbury, Anthony Taylor, Sanskriti Das, Joy Bhattacharya, Manami Roy, Yair Krongold,

Comments: Accepted for publication in ApJ

Subjects: astro-ph.HE astro-ph.GA

Created: 2026-05-19; Updated: 2026-05-21; Datestamp: 2026-05-21

The North Polar Spur (NPS) is a prominent diffuse X-ray feature whose origin has remained uncertain for decades. Using a uniform analysis of archival \textit{SUZAKU} and \textit{XMM--Newton} data with new \textit{Chandra} observations, we constrain its thermal and chemical properties. The NPS emission is fully absorbed by the neutral interstellar medium, demonstrating that the plasma lies beyond the Galactic disk and is not a local SUPERNOVA remnant or nearby superbubble. The spectra require a two-temperature model with a warm--hot component ($kT \approx 0.2$ keV) and a hotter component ($kT = 0.4$--$0.5$ keV), with emission measures of $(41.8 \pm 4.9) \times 10^{-3}$ and $(12.9 \pm 2.2) \times 10^{-3} \mathrm{cm^{-6}~pc}$, respectively. A key result is the detection of super-solar abundance ratios in the warm--hot phase, with N/O $= 3.6 \pm 0.3$ and Ne/O $= 1.9 \pm 0.1$ solar. A SUZAKU observation of the outer South Polar Spur (SPS) shows similar absorption, temperatures, and enhanced abundances (N/O $= 2.9 \pm 0.4$, Ne/O $= 1.6 \pm 0.2$), though with lower emission measures. The similar super-solar abundance ratios suggest a common enrichment history. These properties are consistent with those measured along other sightlines through the X-ray--bright shells of the Galactic bubbles. Together, these results support that the NPS and SPS trace opposite limbs of the Galactic bubbles. The chemical properties suggest a strong contribution from stellar feedback in shaping the Galactic bubbles.

[abstract 29 / 37] (score: 2)
arXiv:2605.20492 [pdf, ps, other]

Title: Remarks on electrical Penrose process for MAGNETized Reissner-Nordström BLACK HOLE

Authors: A. Baez, Nora Breton, I. Cabrera-Munguia,

Comments: 16 pages, 15 figures

Subjects: gr-qc

Created: 2026-05-19; Updated: 2026-05-21; Datestamp: 2026-05-21

The energy extraction from a MAGNETized Reissner-Nordström BLACK HOLE is analyzed within the framework of the electric Penrose mechanism. The presence of an external MAGNETic field induces an axisymmetric configuration and an ergosphere (the region where energy extraction is possible) arises, allowing for negative energy states even in an otherwise static spacetime. By analyzing the decay of particles at turning points of the radial motion, we derive the general expression for the efficiency of the process in terms of the metric coefficients and the electroMAGNETic potential. This formulation provides a direct criterion for identifying the ergoregions and we show that the MAGNETic field acts as a control parameter that governs both the configuration of the ergosphere and the efficiency of the process. In particular, analytical expressions for the critical MAGNETic fields that determine the onset and suppression of energy extraction are determined. Our results extend previous analysis of the electric Penrose process for MAGNETized configurations and clarify the role of the external field in enhancing or inhibiting energy extraction from charged BLACK HOLEs.

[abstract 30 / 37] (score: 2)
arXiv:2605.20493 [pdf, ps, other]

Title: ElectroMAGNETic duality degeneracy in dynamical BLACK HOLE mergers

Authors: José Ferreira, Gabriele Bozzola, Carlos A. R. Herdeiro, Vasileios Paschalidis, Miguel Zilhão,

Comments: 11 pages, 9 figures

Subjects: gr-qc hep-th

Created: 2026-05-19; Updated: 2026-05-21; Datestamp: 2026-05-21

ElectroMAGNETic duality is a symmetry of the source-free Einstein-Maxwell equations that rotates electric and MAGNETic fields while leaving the stress-energy tensor invariant. We present the first fully nonlinear realization of this symmetry in dynamical strong-gravity regimes by performing numerical relativity simulations of charged BLACK HOLE mergers across a continuous duality family. Starting from electrically charged binaries, we generate dyonic and MAGNETically charged configurations via duality rotations and evolve them within a common numerical framework. We find that all dual configurations exhibit identical spacetime dynamics, while the emitted electroMAGNETic radiation is related by a rotation of its POLARIZATION equal to the duality angle. Our results demonstrate a degeneracy of gravitational observables under electroMAGNETic duality and provide a concrete mapping between dual configurations at the level of radiation, establishing electroMAGNETic duality as an organizing principle for dynamical Einstein-Maxwell solutions.

[abstract 31 / 37] (score: 2)
arXiv:2605.20570 [pdf, ps, other]

Title: ModMax-BLACK HOLE surrounded by cloud of strings in Bumblebee gravity

Authors: Fernando M. Belchior, Allan R. P. Moreira, Abdelmalek Bouzenada, Faizuddin Ahmed,

Comments: 29 pages and 11 figures

Subjects: gr-qc

Created: 2026-05-20; Updated: 2026-05-21; Datestamp: 2026-05-21

In this article, we investigate the optical, thermodynamic, and scattering properties of a ModMax BLACK HOLE surrounded by a cloud of strings within the framework of Einstein-bumblebee gravity. We then analyze in detail the thermodynamic properties of this BLACK HOLE, including the Hawking temperature, entropy, and other relevant thermodynamic quantities, and examine the outcomes. Furthermore, we study the greybody factors (GFs) associated with the emission of various perturbative fields propagating in this BLACK HOLE background. In particular, we consider spin-0 scalar fields, spin-1 electroMAGNETic fields, and spin-2 graviton fields, and evaluate the corresponding absorption probabilities and energy emission rates. Our analysis demonstrates how the optical features, thermodynamics and GFs depend on the underlying parameters of the system, such as the Lorentz symmetry violation parameter, the cloud of strings parameter, the ModMax parameter, the electric charge, and the BLACK HOLE mass, thereby providing a comprehensive understanding of the physical effects of these parameters on the radiation and scattering processes around the BLACK HOLE.

[abstract 32 / 37] (score: 2)
arXiv:2605.20622 [pdf, ps, other]

Title: Connecting CGM enrichment with Lyman alpha emitters at 2.9 < z < 6.7

Authors: A. M. Sebastian, E. Ryan-Weber, R. L. Davies, R. A. Meyer, V. D'Odorico,

Comments: 24 pages, 15 figures, Accepted for publication in MNRAS

Subjects: astro-ph.GA

Created: 2026-05-20; Updated: 2026-05-21; Datestamp: 2026-05-21

We present the results of a blind search for Lyman $α$ emitters (LAEs) in three deep archival $z\sim6$ QUASAR fields from VLT/MUSE using state-of-the-art detection algorithms. We explore their connection with absorbers-particularly C IV and Mg II-in the circumgalactic medium (CGM) from the E-XQR-30 survey. We detect 156 LAEs at $2.9QUASAR fields.

[abstract 33 / 37] (score: 2)
arXiv:2605.21064 [pdf, ps, other]

Title: FERMIon condensate at the event horizon

Authors: Vladimir Dzhunushaliev, Vladimir Folomeev,

Comments: 6 pages, 1 figure

Subjects: gr-qc

Created: 2026-05-20; Updated: 2026-05-21; Datestamp: 2026-05-21

Some arguments are considered in favor of the idea that the canonical anticommutation relations for fermions should be modified in curved spacetime near the event horizon of a BLACK HOLE. Such a modification is expected to lead to a change in the source term of the inhomogeneous Dirac equation describing the two-point Green's function. By introducing an {\it ad hoc} source into the Dirac equation that mimics the modification of these anticommutation relations, stationary solutions are obtained and interpreted as two-point Green's functions of fermions located near the event horizon. Owing to their stationarity, these Green's functions describe a fermion condensate near the event horizon.

[abstract 34 / 37] (score: 2)
arXiv:2605.21092 [pdf, ps, other]

Title: Audible Axion Magnetogenesis: Linking Intergalactic Magnetic Fields and Gravitational Waves

Authors: Christopher Gerlach, Daniel Schmitt, Pedro Schwaller,

Comments: 7 pages, 3 figures

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

Created: 2026-05-20; Updated: 2026-05-21; Datestamp: 2026-05-21

Identifying DARK MATTER candidates that simultaneously generate multiple observable cosmological signatures is a key goal in connecting particle physics with upcoming observations. Axion-like particles coupled to the Standard Model photon offer a promising framework. In the trapped misalignment mechanism, the onset of axion oscillations is delayed, inducing a period of supercooling in the early Universe. This can lead to exponential production of photon quanta via a tachyonic instability, generating observable gravitational wave signatures. Simultaneously, reheating of the Standard Model plasma produces strong, helical MAGNETic fields on intergalactic scales. The parameter space most promising for gravitational wave detection yields MAGNETic field strengths that exceed lower bounds from BLAZAR observations.

[abstract 35 / 37] (score: 2)
arXiv:2605.21230 [pdf, ps, other]

Title: Solar Vortices: Catalysts of Magnetoacoustic Wave Dissipation and Atmospheric Heating

Authors: Nitin Yadav, Apanba Khuman,

Comments: Accepted in Frontiers in Astronomy and Space Sciences

Subjects: astro-ph.SR

Created: 2026-05-20; Updated: 2026-05-21; Datestamp: 2026-05-21

The propagation and dissipation of MAGNETohydrodynamic waves play a key role in transporting energy from the solar photosphere to the chromosphere. Using high-resolution three-dimensional radiative MHD simulations, we investigate the evolution of slow MAGNEToacoustic waves along MAGNETic field lines and examine the influence of photospheric vortex flows on wave dynamics and heating. Field-line tracking reveals upward-propagating slow-mode waves that amplify in the stratified atmosphere and steepen into shocks in the chromosphere, producing recurrent plasma surges with characteristic chromospheric shock signatures. Vortex regions are identified using the swirling strength diagnostic with height-dependent Gaussian smoothing to capture expanding vortex structures. A comparison between vortex and non-vortex field lines shows systematically enhanced temperature in vortex regions.Furthermore, a comparison of shock formation height between vortex and non-vortex regions reveals no systematic difference, indicating that rotational flows do not significantly alter the height at which shocks form. However, supersonic upflows at vortex locations exhibit somewhat higher parallel velocities compared to non-vortex regions, suggesting that vortex-driven motions may amplify the velocity of propagating shocks. These results indicate that vortex-driven motions contribute to increased shock dissipation and modify the thermal structure of the lower solar atmosphere, highlighting the coupled role of slow-mode shocks and vortex flows in chromospheric energy transport.

[abstract 36 / 37] (score: 2)
arXiv:2605.21444 [pdf, ps, other]

Title: A Compression-Directional Entropic Stress Method for Shock-Regularized Compressible Flow

Authors: Bonan Xu, Chihyung Wen,

Comments:

Subjects: physics.flu-dyn

Created: 2026-05-20; Updated: 2026-05-21; Datestamp: 2026-05-21

We introduce the Compression-Directional Entropic Stress method (CoDeS), a finite-volume regularization for shock-dominated compressible flows. Inspired by information geometric regularization, CoDeS replaces scalar multidimensional entropic pressure with a tensor stress aligned with the principal directions of compression. The stress has the form $\boldsymbolΠ_Σ=σ\boldsymbol{M}$, where $σ$ is obtained from a modified-Helmholtz equation and $\boldsymbol{M}$ is constructed from the compressive eigenspace of the symmetric velocity-gradient tensor. The source is gated by volumetric and principal-strain compression, so the regularization vanishes in smooth expansion, rigid-body rotation, and ideal contacts, while recovering the compressive one-dimensional IGR mechanism at planar shocks. The same tensor stress is used in the conservative momentum flux and the stress-work energy flux. CoDeS is tested on one-, two-, and three-dimensional problems including smooth expansion, double rarefaction, the Sod shock tube, multidimensional Riemann flow, a viscous shock tube, a two-fluid triple point, a Mach-3 slot JET, and a supersonic Taylor--Green vortex. The results show that CoDeS remains inactive in expansive and contact regions, supplies localized stress at shocks, and concentrates regularization along compressive wave structures while remaining weak in shear- and vorticity-dominated regions. At matched resolutions, the three-dimensional Taylor--Green results are comparable to or more energetic than seventh-order WENO/TENO references. These results indicate that CoDeS provides a compression-selective shock regularization compatible with high-order finite-volume resolution of contacts, interfaces, shear layers, and vortical structures.

[abstract 37 / 37] (score: 2)
arXiv:2605.21469 [pdf, ps, other]

Title: The giant pulse population of PSR B0355+54

Authors: Sergei L. Kurdubov, Dmitry A. Marshalov,

Comments: Submitted to Nature Astronomy

Subjects: astro-ph.HE

Created: 2026-05-20; Updated: 2026-05-21; Datestamp: 2026-05-21

Giant pulses are rare bright radio bursts that occur in restricted ranges of pulsar rotational phase. Here we report giant pulses from PSR B0355+54, a pulsar with spin period ~0.156 s. Using 7.97 hours of observations centred at 1.46 GHz, with 128 MHz bandwidth in each circular POLARIZATIONs, we identify 432 pulse periods containing bright pulses. The giant pulses recur in two compact longitude regions inside the radio emission window. They are narrow compared with the mean profile, with median W50=290.3 us, and reach relative peak flux density ratios up to 149.7. The early longitude group has a timing scatter of 139.7 us, or 8.9*10^{-4} of a rotation. The first longitude group favours right, while the second favours left circular POLARIZATION.