Current date: 2026-06-19

Setting default datestamp limit: 0

Datestamp limit: 2026-06-19 (0 days ago)

Created/updated limit: 2026-06-12 (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=2026-06-19&until=2026-06-19&set=physics&metadataPrefix=arXiv

Scoring abstracts

Number of records retrieved: 728

Keyword score statistics

score 7 -- 2 abstracts

score 6 -- 1 abstracts

score 5 -- 3 abstracts

score 4 -- 3 abstracts

score 3 -- 9 abstracts

score 2 -- 23 abstracts

in total -- 41 abstracts

Articles that appeared on 2026-06-19

[abstract 1 / 41] Wow! (score: 7)
arXiv:2606.19952 [pdf, ps, other]

Title: Accreting stellar-mass BLACK HOLEs

Authors: Greg Marcel, Bailey Tetarenko, Adam Ingram, Tom Maccarone, Alexandra Veledina, Phil Charles,

Comments: 56 pages, 24 Figures. Submitted to SSRv. Comments welcome

Subjects: astro-ph.HE

Created: 2026-06-18; Updated: 2026-06-19; Datestamp: 2026-06-19

Accreting stellar-mass BLACK HOLEs exhibit dramatic variability across the electroMAGNETic spectrum, including spectral state transitions, outbursts, and JET production, making them unique laboratories for understanding accretion processes in strong gravitational fields. This review synthesizes recent progress in understanding these systems, focusing on their continuum emission, timing properties, emission lines, and X-ray POLARIZATION. A complex interplay between the accretion disk, the so-called corona, and JET underlies the observed spectral and timing behavior, with quasi-periodic oscillations and broadband noise providing windows into the dynamics of the innermost accretion flow. Emission lines across all wavelengths serve as critical diagnostics of disk structure, outflows, and reprocessing, while iron K lines in the X-ray band probe the properties of the inner disk through RELATIVISTIC reflection. Polarization studies suggest that the corona is likely extended perpendicular to the JET axis in the hard state, while the soft state remains poorly understood, with observations that do not yet conform to simple theoretical expectations; a puzzle that continues to challenge our interpretation of accretion geometry. Despite significant advances, fundamental questions remain about the physical origins of state transitions, the role of MAGNETic fields in driving outflows and shaping the accretion flow, and the connection between disk instabilities and JET launching. This review underscores the need for future multi-wavelength, timing, and polarimetric studies to deepen our understanding of accretion physics in strong-gravity environments.

[abstract 2 / 41] Wow! (score: 7)
arXiv:2606.20335 [pdf, ps, other]

Title: A merger shock traced by radio arcs and ultra-long radio tails in galaxy cluster A2142

Authors: Chong Ge, Ming Sun, Chris Nolting, Fabio Gastaldello, Dominique Eckert,

Comments: 13 pages, 5 figures, submitted to ApJ

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

Created: 2026-06-18; Updated: 2026-06-19; Datestamp: 2026-06-19

Abell 2142 (A2142) is a massive, nearby galaxy cluster undergoing a complex merger. It exhibits an elongated X-ray morphology along the northwest-southeast axis and hosts four known cold fronts. Using XMM-Newton observations, we detect a merger shock on the northwest side of the cluster with a Mach number of $M \sim 1.3$. The observed shock front and four cold fronts can be reproduced by numerical simulations of an off-axis merger with a large impact parameter, which imparts significant angular momentum to induce the sloshing of the subcluster core and large-scale ambient gas. In projection, the shock front is spatially coincident with arc-shaped radio filaments observed behind the prominent head-tail RADIO GALAXies T1 and T2. We interpret these radio arcs as partial vortex ring structures (resembling ``smoke rings'') produced by the interaction of the merger shock with the low-density cocoons of RADIO GALAXies. The shock strips and rolls the JET cocoon into a toroidal vortex, as predicted by recent MAGNETohydrodynamic simulations. We further demonstrate that the merger shock can significantly elongate the radio tails by re-accelerating aged RELATIVISTIC electrons and stretching the tail plasma via the post-shock wind. This process provides a natural explanation for the $>$500 kpc tail observed in this and other merging clusters. Our findings establish radio arcs and ultra-long radio tails as independent, complementary tracers of merger shocks in galaxy clusters. Our results demonstrate that merger shocks can reshape both the thermal and non-thermal components of galaxy clusters, and that tailed RADIO GALAXies serve as sensitive probes of intracluster medium weather.

[abstract 3 / 41] Yes (score: 6)
arXiv:2304.06482 [pdf, ps, other]

Title: The Capella Program: Toward A Space-only High-frequency Radio VLBI Network Formed by Small Satellites in Low Earth Orbits

Authors: Sascha Trippe, Taehyun Jung, Jung-Won Lee, Jan Wagner, Jeong-Yeol Han, Doohyon Baek, Wonseok Kang, Jae-Hyun Kyeong, Junghwan Oh, Jae-Young Kim, Jongho Park, Sang-Sung Lee, Jeffrey A. Hodgson, Taeho Kang,

Comments: 23 pages, 4 figures, 2 tables. Whitepaper version 2.0. Includes the Mimosa pathfinder mission. Abstract abridged. Living document, will be updated when necessary

Subjects: astro-ph.IM

Created: 2026-06-18; Updated: 2026-06-19; Datestamp: 2026-06-19

Very long baseline radio interferometry (VLBI) with ground-based observatories is limited by the size of Earth, the geographic distribution of antennas, and the transparency of the atmosphere. In this whitepaper, we present a design for a space-to-space VLBI program composed of two missions: Mimosa, a pathfinder, and Capella, a science-grade VLBI observatory. Mimosa is a two-element space-to-space radio interferometer composed of two small (250 kg) satellites on co-planar polar circular low Earth orbits. Using single-band, single-circular POLARIZATION heterodyne HEMT receivers operating at frequencies around 100 GHz, the interferometer is able to achieve a near-perfect visibility plane coverage and an angular resolution of approximately 35 microarcsec. Capella comprises four small (500 kg) satellites in two orthogonal polar low-Earth orbit planes. With single-band heterodyne receivers operating at frequencies around 690 GHz, the interferometer is able to achieve angular resolutions of approximately 7 microarcsec. Within a total observing time of three days, a near-complete uv plane coverage can be reached. The technology for all key components required - radio telescope, receiver, sampler, recorder, frequency standard, positioning system, data downlink, and pointing control system - is already available, partially off-the-shelf. Capella will be able to address a range of science cases, including: the shadows of supermassive BLACK HOLEs; the acceleration and collimation zones of plasma JETs emitted from the vicinity of supermassive BLACK HOLEs; the chemical composition of accretion flows into ACTIVE GALACTIC NUCLEi through observations of molecular absorption lines; mapping supermassive binary BLACK HOLEs; the MAGNETic activity of stars; and nova eruptions of symbiotic binary stars -- and, like any substantially new observing technique, has the potential for unexpected discoveries.

[abstract 4 / 41] Yes (score: 5)
arXiv:2603.25949 [pdf, ps, other]

Title: General-RELATIVISTIC and non-ideal radiative cooling in neutron star MAGNETospheres

Authors: João Joaquim, Francisco Assunção, Pablo J. Bilbao, Luis O. Silva,

Comments: 12 pages, 5 figures

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

Created: 2026-06-18; Updated: 2026-06-19; Datestamp: 2026-06-19

Radiation reaction cooling plays an important role in describing the extreme plasma conditions found in the MAGNETospheres of astrophysical compact objects. Strong electroMAGNETic fields, characteristic of these environments, can trigger the development of anisotropic ring-shaped plasma distributions with inverted Landau populations in momentum space. In this work, we present the first systematic investigation of this mechanism in realistic astrophysical configurations, by accounting for how non-uniform electroMAGNETic field geometries and general-RELATIVISTIC effects modify the phase-space dynamics of radiatively cooled plasmas. We demonstrate analytically that drift velocities favour the formation of spiral-shaped momentum distributions that still display inverted Landau populations, and estimate the minimum and maximum plasma injection distances required for inverted momentum distributions to be able to power the emission of coherent radiation through kinetic instabilities. From numerical simulations, we conclude that curved spacetime increases the gradient of the distribution function responsible for the development of kinetic instabilities, and prolongs the persistence of the inverted momentum structure relative to flat spacetime, confirming that realistic astrophysical conditions preserve and enhance the conditions necessary for SYNCHROTRON-powered emission of coherent radiation to occur.

[abstract 5 / 41] Yes (score: 5)
arXiv:2606.19448 [pdf, ps, other]

Title: Damping of Fast Radio Bursts in the Inner Magnetospheres of Magnetars

Authors: Siddhant Solanki, Jens Mahlmann, Alexander Philippov, Andrei Beloborodov,

Comments: 9 pages, 3 figures, submitted to the Astrophysical Journal Letters

Subjects: astro-ph.HE

Created: 2026-06-17; Updated: 2026-06-19; Datestamp: 2026-06-19

We investigate the propagation of fast radio bursts (FRBs) through MAGNETar MAGNETospheres. Previous work showed that, in the inner MAGNETosphere, GHz radio waves propagate as fast MAGNETosonic waves and undergo resonant three-wave interactions that transfer their energy into trapped Alfvén waves. Using three-dimensional force-free electrodynamics simulations, we demonstrate that FRBs would excite Alfvénic fluctuations, leading to strong nonlinear attenuation of the radio signal. In quiescent dipolar MAGNETospheres, the nonlinear decay stays efficient within $\sim10$--$100$ MAGNETar radii; charge starvation of the excited Alfvén waves stops the decay at larger radii. For FRBs propagating within RELATIVISTIC MAGNETic outflows launched during MAGNETospheric eruptions, three-wave interactions remain efficient and constrain the escape radius to $\gtrsim10^2$--$10^3$ MAGNETar radii for luminous bursts. Our results confirm that nonlinear plasma processes strongly limit the escape of FRBs from the inner MAGNETospheres of MAGNETars.

[abstract 6 / 41] Yes (score: 5)
arXiv:2606.19450 [pdf, ps, other]

Title: Nonlinear Decay of Fast Magnetosonic Waves through Weak Turbulence: Force-Free Electrodynamics Simulations

Authors: Siddhant Solanki, Jens Mahlmann, Alexander Philippov,

Comments: 22 pages, 9 figures, submitted to The Astrophysical Journal

Subjects: astro-ph.HE

Created: 2026-06-17; Updated: 2026-06-19; Datestamp: 2026-06-19

We investigate the propagation of low-frequency fast-MAGNETosonic (FMS) waves in highly MAGNETized environments. Such conditions are relevant to the escape of GHz fast radio bursts potentially produced in the inner MAGNETospheres of MAGNETars. It remains an open question whether such waves can escape without substantial reprocessing. Using RELATIVISTIC force-free electrodynamics simulations, we confirm the key theoretical predictions of Golbraikh & Lyubarsky (2023) and demonstrate that FMS waves undergo efficient nonlinear conversion into secondary FMS and Alfvén waves via the parametric decay instability. This process continues to drain energy from the primary FMS waves even after approximate energy equipartition between the FMS and Alfvén components is established. The resulting spectrum of excited waves is broad, extending across much of the inertial range in $k$-space within the simulation domain. Our results indicate that FMS waves likely do not escape MAGNETar MAGNETospheres without substantial dissipation and spectral broadening.

[abstract 7 / 41] Yes (score: 4)
arXiv:2606.19445 [pdf, ps, other]

Title: Evidence for protostellar JETs as a population of hadronic gamma-ray sources

Authors: Javier Méndez-Gallego, Rubén López-Coto, Emma de Oña Wilhelmi, Stefano Menchiari, Iván Agudo, Rubén Fedriani,

Comments: Published in Nature Astronomy

Subjects: astro-ph.HE astro-ph.SR

Created: 2026-06-17; Updated: 2026-06-19; Datestamp: 2026-06-19

Stars are born in darkness, deep within cold, dense molecular clouds where gravity drives the collapse of gas and dust, giving rise to protostars, the earliest stages of stellar evolution. Once considered purely thermal sources, these young systems are now emerging as sites of energetic non-thermal activity. While radio SYNCHROTRON JETs hinted at the presence of RELATIVISTIC electrons, direct confirmation of proton acceleration remained elusive. Here we report a statistically significant detection of gamma rays from a population of young stellar objects, revealing a Galactic class of Gamma-Loud Protostars. Observations point towards particle acceleration within protostellar JETs, where gamma-ray emission arises from protons interacting with surrounding molecular clouds via pion decay. We find a correlation between cosmic-ray output and bolometric luminosity, suggesting that particle acceleration scales with the system's mechanical power. These findings open a new observational window into the role of non-thermal processes in protostellar evolution and suggest that gamma-ray studies of protostars can provide critical insights into accretion, ejection, and feedback in STAR FORMATION. This previously overlooked emission traces the energetic feedback that young stars inject into their surroundings, shaping the conditions for subsequent star and planet formation.

[abstract 8 / 41] Yes (score: 4)
arXiv:2606.19546 [pdf, ps, other]

Title: Effects of the Background Magnetic Field on Flux Rope Eruptions

Authors: Xianyu Liu, Spiro K. Antiochos, Igor V. Sokolov, Tamas I. Gombosi, Bart van der Holst, Gábor Tóth, Nishtha Sachdeva, Lulu Zhao,

Comments: 24 pages, 10 figures, 2 tables

Subjects: astro-ph.SR

Created: 2026-06-17; Updated: 2026-06-19; Datestamp: 2026-06-19

Solar eruptive events are generally believed to involve MAGNETic flux ropes (MFR), formed either in the pre-eruptive phase of the event or during the eruption itself. These MFR eruptions exhibit significant complexity and variations due to the interplay of the physical mechanisms involved, in particular MAGNETic RECONNECTion and ideal instabilities. This work considers the effect of the background MAGNETic field on the nature of eruptions with pre-existing MFRs. We used a new MHD model to simulate the whole MFR eruption process, including the pre-eruptive stage and the initiation. Three simulations were performed, all of which used an identical bipolar active region, but with different background MAGNETic fields in the three cases. The simulations resulted in two successful eruptions (CMEs) and one failed eruption (a confined flare). We analyzed the energetics and the acceleration of the MFR in detail, and found a transition to a rapid exponential rise phase in two of the simulations. We also calculated the criterion for the torus instability and the timing of the breakout and flare RECONNECTions. Our results show that the rapid exponential rise phase is likely due to breakout RECONNECTion. We conclude that a background field antiparallel to the active-region field lowers the MAGNETic free-energy threshold for eruption; but, does not guarantee a successful eruption. We also found that an antiparallel background field leads to faster flare RECONNECTion, but of shorter duration. Our findings underscore the importance of the background MAGNETic field in understanding CMEs.

[abstract 9 / 41] Yes (score: 4)
arXiv:2606.19757 [pdf, ps, other]

Title: Graviton Floor

Authors: Himeka Matsuo, Asuka Ito, Kazunori Kohri, Teruaki Suyama, Ryutaro Tomomatsu,

Comments: 16pages, 3 figures

Subjects: gr-qc astro-ph.CO hep-ph

Created: 2026-06-18; Updated: 2026-06-19; Datestamp: 2026-06-19

It has been observed that the Universe is permeated by the cosmic photon background, ranging from radio waves to gamma rays. We investigate the conversion of the photon background into gravitons in the presence of background MAGNETic fields in the Milky Way Galaxy and in BLAZAR JETs. We find that the resulting graviton background is dominated by the contribution generated in BLAZAR JETs. Importantly, this graviton background constitutes a graviton floor for high-frequency gravitational wave detectors searching for new physics, analogous to the neutrino floor.

[abstract 10 / 41] (score: 3)
arXiv:2510.18445 [pdf, ps, other]

Title: Discovery of Repeating Transitions in 16 Changing-look Active Galactic Nuclei

Authors: Qian Dong, Zhi-Xiang Zhang, Wei-Min Gu, Mouyuan Sun, Wei-Jian Guo, Zhen-Yi Cai, Jun-Xian Wang, Yong-Gang Zheng,

Comments: 17 pages, 6 figures, 2 tables, accepted for publication in ApJ

Subjects: astro-ph.GA

Created: 2026-06-18; Updated: 2026-06-19; Datestamp: 2026-06-19

The repeating changing-look ACTIVE GALACTIC NUCLEi (RCL AGNs) exhibit multiple appearances and disappearances of broad emission lines (BELs), whose underlying mechanism remains a puzzle. Expanding the sample of RCL AGNs is valuable for constraining the transition timescale and probing the accretion physics driving CL behaviors. This study aims to identify RCL AGNs using the multi-epoch spectroscopic data of confirmed CL AGNs from the Sloan Digital Sky Survey, Large Sky Area Multi-Object Fiber Spectroscopic Telescope, and Dark Energy Spectroscopic Instrument, supplemented with mid-infrared (MIR) light curves. Through selection criteria and visual inspection, we identify 22 RCL AGNs among 299 CL AGNs, corresponding to an occurrence rate of about 7\%, indicating that repeated transitions are not extremely rare in CL AGNs. Among the 22 RCL AGNs, 16 are newly identified, which significantly expands the known RCL AGN sample. Based on the spectra and densely sampled MIR light curves, we derive MIR variability timescales for 18 RCL AGNs, and find no significant correlation between the timescale and the BLACK HOLE mass.

[abstract 11 / 41] (score: 3)
arXiv:2512.11656 [pdf, ps, other]

Title: The multiphase interstellar medium as a common origin for MAGNETic misalignment and TB parity violation

Authors: Andrea Bracco, Ari J. Cukierman, Raphael Skalidis, François Boulanger,

Comments: Accepted by A&A on May 21, 2026

Subjects: astro-ph.GA astro-ph.CO

Created: 2026-06-17; Updated: 2026-06-19; Datestamp: 2026-06-19

We present an original data analysis and a physical model that provide new insights into the origin of, and relationship between, two observables of the dusty, polarized Galaxy at intermediate and high latitudes: (i) the misalignment between HI filamentary structures and MAGNETic fields and (ii) the positive $TB$ correlation measured in Planck data suggesting parity violation in the interstellar medium (ISM). We confirm an observational link between the two effects and find that both are predominantly produced at large angular scales ($\geq 10^\circ$, multipoles $\ell \leq 20$) with a significantly stronger signal in the northern hemisphere. We propose a model in which filaments and MAGNETic fields appear misaligned in projection because they are sourced by cold and warm gas phases distributed in different proportions in the Solar neighborhood, from the wall of the Local Bubble to larger distances. These projection effects at large angular scales can produce coherent signatures that propagate to smaller scales in power spectra without invoking local, small-scale filament misalignment. Within this frame, HI filaments remain statistically aligned with the MAGNETic field in 3D, although with a projected scatter of tens of degrees that requires further investigation. The multiphase, geometrical model presented in this work is supported by Planck POLARIZATION data at 30 GHz, where SYNCHROTRON radiation dominates, and at 217 and 353 GHz, where dust emission dominates. Our analysis also incorporates starlight POLARIZATION measurements. The model introduced here suggests a new interpretation of two unexplained observables and emphasizes the role of the large-scale MAGNETized ISM in shaping polarized Galactic emission, which has important implications for both Galactic astrophysics and cosmological foreground characterization.

[abstract 12 / 41] (score: 3)
arXiv:2601.02812 [pdf, ps, other]

Title: Beyond Sgr A* and M87*: Sub-Microarcsecond Black Hole Shadow Detection via Lunar-based Extremely Long Baseline Interferometry

Authors: Shan-Shan Zhao, Ru-Sen Lu, Lei Liu, Zhiqiang Shen, Yosuke Mizuno,

Comments:

Subjects: astro-ph.GA astro-ph.IM

Created: 2026-06-18; Updated: 2026-06-19; Datestamp: 2026-06-19

The 1.3 mm ground-based very long baseline interferometry (VLBI) array Event Horizon Telescope (EHT), is limited by Earth's diameter, restricting its BLACK HOLE shadow imaging to only M87* and Sgr A*. Extending baselines to the Moon would achieve ~0.7 uas angular resolution at 230 GHz, enabling shadow detection for a much larger sample of supermassive BLACK HOLEs (SMBHs). The concept is motivated by space VLBI missions and lunar exploration, including the ongoing Lunar Orbit VLBI EXperiment (LOVEX) aboard QueQiao-2 (Chang'E-7) and the planned International Lunar Research Station (ILRS). We assess shadow detectability for 31 SMBHs with predicted large angular sizes, exploring different telescope location and antenna size. Assuming a telescope at the lunar antipode, we simulate the Moon-Earth (u,v) coverage and show that sources with direction near the Moon's orbital plane yield projected baselines spanning from short to long, enabling sampling of the first visibility null - a key shadow signature. Using a geometric ring model, we identify six shadow-detectable candidates for Moon-Earth VLBI. Among these, M104, NGC 5077, and NGC 1052 are detectable with a 5 m lunar-based telescope; PGC 049940 requires 10 m; NGC 524 requires 20 m; and NGC 5252 requires 40 m. Furthermore, if space telescopes fill the baseline coverage gaps between Moon and Earth, the n=2 photon ring region is detectable for Sgr A*, M87* with a 10 m lunar-based telescope, and 12 candidates are detectable for the n=1 photon ring region using a lunar-based telescope of up to 40 m. These results provide a clear scientific and technical motivation for lunar-based telescopes in future BLACK HOLE shadow studies.

[abstract 13 / 41] (score: 3)
arXiv:2604.01825 [pdf, ps, other]

Title: The Real and Pseudo Dispersion Measures of FRB~20220912A

Authors: Yi Feng, Dengke Zhou, Y. -K. Zhang, D. Li, Jianhua Fang, Jiaying Xu, Chenyuan Xu, Jintao Xie,

Comments: 8 pages, 3 figures, 2 tables

Subjects: astro-ph.HE

Created: 2026-06-18; Updated: 2026-06-19; Datestamp: 2026-06-19

Fast radio bursts (FRBs) are millisecond-duration radio transients. As they propagate through the interstellar medium, they interact with free electrons, resulting in dispersion. The corresponding dispersion measure (DM) is referred to as the real DM (DM$_{\rm real}$). In practice, however, the dispersion measure derived from modeling (DM$_{\rm model}$) is often contaminated by intrinsic burst morphology, giving rise to a pseudo DM component (DM$_{\rm pseudo} = {\rm DM}_{\rm model} - {\rm DM}_{\rm real}$). In this work, we focus on the highly active repeating FRB~20220912A and utilize its microshots -- extremely short-duration (typically tens of microseconds), broadband emissions -- to investigate its DM$_{\rm real}$ and DM$_{\rm pseudo}$. We adopt two assumptions: first, that FRB~20220912A resides in a non-MAGNETo-ionic environment and that its DM$_{\rm real}$ variation is smaller than $10^{-2}$\,pc\,cm$^{-3}$ over a few years; and second, that microshots have a negligible intrinsic morphological time delay. By identifying two new microshots and combining them with previously reported ones, we find that all four microshots exhibit remarkably consistent DM values over a one-month timescale, with an average of $219.380 \pm 0.004\,\mathrm{pc\,cm^{-3}}$. We define this value as the DM$_{\rm real}$ of FRB~20220912A. We further show that bright, narrow bursts with a width of less than 2\,ms also yield DM estimates consistent with the microshot-based DM$_{\rm real}$. A survey of five repeating FRBs reveals that DM$_{\rm pseudo}$ is a common phenomenon, with variations typically spanning a range of approximately $10\,\mathrm{pc\,cm^{-3}}$ at 1.2\,GHz. These findings highlight the importance of accounting for morphological contributions in DM interpretation and demonstrate that microshots and narrow bursts are powerful tools for probing DM$_{\rm real}$.

[abstract 14 / 41] (score: 3)
arXiv:2606.18998 [pdf, ps, other]

Title: Searching for a superdisk in RADIO GALAXy J0116-473

Authors: Ankur Sinha, Riya Rathore, Narendra Nath Patra, Abhirup Datta,

Comments: 13 pages, 5 figures, submitted to Journal of Astrophysics and Astronomy, comments are welcome

Subjects: astro-ph.GA

Created: 2026-06-18; Updated: 2026-06-19; Datestamp: 2026-06-19

Superdisks have emerged as an active area of research in recent years, and J0116-473 represents a promising target for studying this extended structure. Our primary objective was to search for HI absorption associated with the suspected superdisk. However, no such absorption feature was detected, suggesting a low, or absence of neutral hydrogen content in the superdisk. In addition, we examined a compact point source located near the galaxy's core and the presumed plane of the superdisk, enabling us to search for HI absorption against this background continuum. We also present a detailed multi-band morphological analysis of the galaxy using Giant Metrewave Radio Telescope (GMRT) observations in Bands 3, 4, and 5. A spectral analysis of both the galaxy and the nearby point source was carried out using data from these three frequency bands. A systematic steepening of the spectral index is observed from the core toward the lobes, as expected for aging SYNCHROTRON-emitting plasma. We also found that the northern inner lobe exhibits a significantly steeper spectrum than its southern counterpart, possibly reflecting environmental effects associated with the proposed superdisk. Since superdisks are expected to contain hot, ionized gas, we additionally examined archival X-ray observations from the XMM-Newton telescope. Although diffuse X-ray emission associated with the radio lobes is visible, no significant emission is detected from the region corresponding to the suspected superdisk.

[abstract 15 / 41] (score: 3)
arXiv:2606.19665 [pdf, ps, other]

Title: The Effects of Energy Conservation in Simulating Solar Eruptions

Authors: Xianyu Liu, Spiro K. Antiochos, Nishtha Sachdeva, Gábor Tóth, Ward B. Manchester, Bart van der Holst, Igor V. Sokolov, Tamas I. Gombosi, Lulu Zhao,

Comments: 13 pages, 4 figures

Subjects: astro-ph.SR

Created: 2026-06-18; Updated: 2026-06-19; Datestamp: 2026-06-19

Strict energy conservation is, perhaps, the most basic principle in all physics, but has proven to be difficult to satisfy in numerical simulations of solar eruptions. The Alfvén Wave Solar atmosphere Model (AWSoM) is used to perform a rigorous comparison of CME simulations whose only difference is the use of a conservative vs. non-conservative scheme for the energy equation. A simple, symmetric active region is assumed for the initial MAGNETic field. As expected, the different numerical schemes result in very different plasma thermal energy, but surprisingly, we also find a factor $>2$ difference in the final kinetic energy, with the energy substantially larger in the energy-conservative scheme. The increase in thermal energy is comparable to the increase in kinetic energy in the conservative simulation. Our analysis reveals that the flare RECONNECTion and increase of kinetic energy terminate earlier with the non-conservative scheme. We conclude that the plasma thermodynamics plays a critical role in the flare RECONNECTion, with the thermal pressure gradient in the current sheet slowing down the RECONNECTion. Our results imply that using strict energy-conservative numerics is critical for space weather modeling of CMEs and for understanding the CME energy budget partitioning.

[abstract 16 / 41] (score: 3)
arXiv:2606.20204 [pdf, ps, other]

Title: Solar Wind Dependence on Source Distance from the Open-Closed Boundary

Authors: Chloe P. Wilkins, David I. Pontin, Anthony R. Yeates, Nicholeen M. Viall, Spiro K. Antiochos,

Comments: 17 pages, 11 figures

Subjects: astro-ph.SR

Created: 2026-06-18; Updated: 2026-06-19; Datestamp: 2026-06-19

The origin and variability of the slow solar wind remains an open question in solar physics, but is thought to be closely linked to dynamics at the Sun's open-closed MAGNETic flux boundary (OCB). Interchange MAGNETic RECONNECTion at the OCB has been proposed as a mechanism for releasing closed-field plasma into the heliosphere, but observational evidence linking solar wind composition to OCB topology remains limited. We relate in situ solar wind measurements by Ulysses over a 10-year period to the MAGNETic topology of their source regions using two coronal MAGNETic field models: a potential field source surface model and a MAGNETofrictional model. We find a strong dependence of solar wind composition on the distance of the source MAGNETic flux from the OCB. Enhanced ion charge-state ratios, elemental abundances, and compositional variability are found to be concentrated within a supergranular-scale region (around 25 Mm) surrounding the OCB, consistent with the spatial scales of interchange MAGNETic RECONNECTion. This variability decreases systematically with increasing distance from the boundary, with coronal hole wind exhibiting more uniform fast-wind signatures. We also find that the composition of solar wind emerging from regions close to the OCB is influenced by the strength of neighbouring closed MAGNETic fields, with stronger fields preferentially associated with slow-wind properties. These results indicate that the composition of the slow wind is strongly governed by the MAGNETic topology of the OCB, providing compelling evidence that interchange RECONNECTion plays a crucial role in slow solar wind release and structure.

[abstract 17 / 41] (score: 3)
arXiv:2606.20308 [pdf, ps, other]

Title: Evidence for candidate X-ray pulsations from the ultraluminous X-ray source NGC 7456 ULX-1

Authors: Yuanle Yao, Xiang-Dong Li, Xiao-Jie Xu,

Comments: 12 pages, 7 figures, to be published in ApJ

Subjects: astro-ph.HE

Created: 2026-06-18; Updated: 2026-06-19; Datestamp: 2026-06-19

We report evidence for a candidate pulsational signal at $\sim0.22$~Hz from NGC7456 ULX-1, a previously identified ultraluminous X-ray source (ULX). The signal is identified in the 2023 XMM-Newton observation using independent timing techniques including accelerated searches, $Z^2_n$ statistics, and an orbital-demodulation analysis designed to restore phase coherence in the presence of binary motion. The candidate pulsation frequency drift within the observation suggests rapid spin evolution driven by accretion torque. We further estimate the surface dipole MAGNETic field strength to be $B\sim 10^{12}-10^{14}$ G. These results provide evidence that NGC7456 ULX-1 may host an accreting neutron star, although confirmation with independent datasets or additional observations is required.

[abstract 18 / 41] (score: 3)
arXiv:2606.20368 [pdf, ps, other]

Title: DEM analysis of the 6 September 2011 large-scale coronal wave

Authors: Amaia Razquin, Astrid M. Veronig, Karin Dissauer,

Comments:

Subjects: astro-ph.SR

Created: 2026-06-18; Updated: 2026-06-19; Datestamp: 2026-06-19

Large-scale coronal waves are globally propagating intensity enhancements in extreme-ultraviolet (EUV) and soft X-ray (SXR) observations, associated with solar flares and coronal mass ejections (CMEs). They are interpreted as low-coronal signatures of a large-amplitude fast MAGNETosonic wave. On 6 September 2011, a fast (v = 1000 km/s) large-scale coronal wave accompanied an eruptive X2.1 class flare. A segment of the wave front temporarily dissappeared in EUV channels sensitive to quiet-Sun plasma, while it remained visible in higher temperature channels. We apply differential emission measure (DEM) diagnostics to SDO/AIA EUV observations to derive local density, temperature, emission measure, and DEM distributions, and examine their temporal evolution during the wave passage. The wave passage causes increases of 6-8% in density and 10-18% in temperature. While the density increase is comparable to earlier reports, the temperature increase exceeds expectations. This indicates that the temperature enhancement cannot be explained by compressional adiabatic heating alone, and instead suggests the presence of additional heating mechanisms, such as MAGNETic RECONNECTion or wave mode conversion. During the temporary disappearance of the wave, the plasma parameters at the wave front increase, but with a strong spatial variability, with density increases ranging from 1% to 10%. The initial temperature in the affected area is notably higher than typical quiet-Sun regions (T > 1.7 MK), which allows plasma to be heated beyond the peak response of the AIA 193 and 211 Åchannels. We conclude that the apparent temporary disappearance of the wave front is primarily due to the combined effects in the intensity of the CME-associated coronal dimming following the wave and the wave itself, with heating further reducing its detectability in channels sensitive to quiet-Sun temperatures.

[abstract 19 / 41] (score: 2)
arXiv:2508.07961 [pdf, ps, other]

Title: Gravitational Wave Signatures of Quasi-Periodic Eruptions: LISA Detection Prospects for RX J1301.9+2747

Authors: Leif Lui, Alejandro Torres-Orjuela, Rudrani Kar Chowdhury, Lixin Dai,

Comments: Published in ApJ (https://iopscience.iop.org/article/10.3847/1538-4357/ae71cc)

Subjects: astro-ph.HE gr-qc

Created: 2026-06-18; Updated: 2026-06-19; Datestamp: 2026-06-19

Quasiperiodic eruptions (QPEs) are intense, recurring outbursts of X-ray radiation originating from the nuclei of distant galaxies. One of the promising models of QPE explains these eruptions using extreme-mass-ratio inspirals (EMRIs), in which a stellar-mass object-such as a star or a stellar-mass BLACK HOLE-orbits a central massive BLACK HOLE (MBH) and periodically plows through its accretion disk. In this work, we compute the gravitational wave (GW) signals emitted by such EMRI systems. We find that the physical drag and perturbations due to shock caused by the orbiter-disk collisions leave a distinct imprint on the emitted waveforms. Rather than the smooth, monochromatic evolution observed in vacuum systems, these interactions excite non-discrete modes that manifest as subtle shifts in the orbital frequency and as high-frequency ``tails'' in the signal spectrum. We demonstrate as an example outcome of our model that a specific QPE source RX J1301.9+2747 could be detectable by future space-based GW detectors, provided the orbiter maintains a moderate eccentricity of approximately $0.25$ and a mass exceeding $35\;M_\odot$. Our analysis shows that the signal-to-noise ratio for these events would be high enough to clearly distinguish them from standard vacuum EMRIs. Consequently, GW observations offer a powerful tool to probe the dense environments surrounding MBHs and could give further insight into the elusive origins of QPEs.

[abstract 20 / 41] (score: 2)
arXiv:2510.22910 [pdf, ps, other]

Title: Discovery and Timing Follow-Up of Two FAST-Discovered Pulsars from the FAST CRAFTS Survey

Authors: Victoria A. Blackmon, Maura A. McLaughlin, De Zhao, Jianping Yuan, Qingdong Wu, Chen-Chen Miao, Meng-Yao Xue, Di Li, Wei-Wei Zhu,

Comments: 9 pages, 4 figures, 2 tables

Subjects: astro-ph.HE

Created: 2026-06-17; Updated: 2026-06-19; Datestamp: 2026-06-19

We present the results of Green Bank Telescope (GBT) observations of two pulsars discovered with the Five-hundred-meter Aperture Spherical Radio Telescope (FAST) during the 19-beam Commensal Radio Astronomy FasT Survey (CRAFTS). We highlight the first timing solutions, pulse profiles, flux densities, and POLARIZATION measurements at 820 MHz for PSR J0535-0231, with a spin period of 415 ms, and PSR J1816-0518, with a spin period of 1.93 s, from a year-long follow-up campaign. PSR J0535-0231 appears to be partially recycled, but isolated, and likely belongs to the class of disrupted recycled pulsars (DRPs). We find that the two widely used electron density models, NE2001 and YMW16, both fall short of accurately modeling the line-of-sight to PSR J0535-0231, as the maximum dispersion measure (DM) predicted by both models is lower than the pulsar's DM of 118.1 pc cm$^{-3}$. Finally, we place both pulsar discoveries in the context of other FAST pulsars discovered in the CRAFTS survey and of the currently known pulsar population, in general, and discuss ways in which future FAST discoveries of faint, distant pulsars might facilitate the development of improved versions of the aforementioned electron density models in certain regions of our Galaxy.

[abstract 21 / 41] (score: 2)
arXiv:2512.08116 [pdf, ps, other]

Title: Universality in quasinormal modes of a MAGNETized BLACK HOLE

Authors: Marcos R. Ribeiro, Eveling C. Ribeiro, Kai Lin, Elcio Abdalla,

Comments: 10 pages, 6 figures. Accepted for publication in Physical Review D

Subjects: gr-qc

Created: 2026-06-18; Updated: 2026-06-19; Datestamp: 2026-06-19

In this work, we investigate the linear stability of a MAGNETized Einstein-Maxwell solution describing a static, axially symmetric BLACK HOLE (BH) immersed in a uniform MAGNETic field $B$. We probe the dynamics of an external charged scalar field through its quasinormal modes (QNMs), combining frequency- and time-domain analyses. We find a critical value of the field charge at which the QNM spectrum exhibits universal power-law scaling with an exponent of approximately $1/2$. This critical behavior admits a simple interpretation in terms of a transition between a confined regime, where waves remain effectively trapped within a region of characteristic size $\sim 1/B$, and a deconfined regime, where the field reaches distances $\gg 1/B$ and the damping rate becomes parametrically small. These results provide qualitative and quantitative insights that may inform more realistic scenarios involving highly MAGNETized compact objects.

[abstract 22 / 41] (score: 2)
arXiv:2601.12999 [pdf, ps, other]

Title: BE Lyncis: A Pulsating Star in the Most Eccentric Binary with a Massive Unseen Companion

Authors: Jia-Shu Niu, Ying Zhang, Hui-Fang Xue,

Comments: 17 pages, 5 figures, 4 tables. ApJL accepted

Subjects: astro-ph.SR astro-ph.HE

Created: 2026-06-18; Updated: 2026-06-19; Datestamp: 2026-06-19

We report the discovery of an exceptionally eccentric binary system, BE Lyncis (BE Lyn), which might host a compact companion with mass $\gtrsim 2.5~M_{\odot}$. By combining TESS photometry with an extensive set of times of maximum light spanning 39 years, we identify BE Lyn as a high-amplitude $δ$ Scuti star in a binary with an orbital period of $\approx15.9$ years and an extraordinary eccentricity of $e=0.9989^{+0.0008}_{-0.0021}$ ($>0.9968$ at 95% confidence) -- the most extreme eccentricity reliably measured for any binary system. Dynamical constraints limit the orbital inclination to $i \lesssim 10^{\circ}.1$, implying a companion mass $M_2 \gtrsim 2.5~M_{\odot}$, which identifies the companion as a compact object. This mass points to it most likely being a BLACK HOLE; if instead it is a rapidly rotating neutron star, it would be the most massive known. If the BLACK HOLE interpretation holds, it would be the closest such object to Earth. This system provides a unique laboratory for studying asteroseismology in strong gravitational fields, as well as the formation and evolution of extremely eccentric binaries. Our work demonstrates the use of the light-travel time effect in a pulsating star to reveal a compact companion, offering a novel method for detecting BLACK HOLEs in noninteracting binaries.

[abstract 23 / 41] (score: 2)
arXiv:2601.15661 [pdf, ps, other]

Title: Non-Ambipolarity of Microturbulent Transport

Authors: Allen H Boozer,

Comments:

Subjects: physics.plasm-ph

Created: 2026-06-18; Updated: 2026-06-19; Datestamp: 2026-06-19

When exact MAGNETic surfaces are assumed to exist, the gyrokinetic theory of microturbulence gives the same radial transport for ions and electrons. But, exact MAGNETic surfaces do not exist in the presence of what is called electrostatic microturbulence. When the plasma pressure is non-zero, a turbulent electric potential is accompanied by a turbulent MAGNETic field, which splits the rational MAGNETic surfaces with which it resonates. If the MAGNETic field is assumed to have an ideal topology-conserving evolution, delta function current densities arise on resonant surfaces. The singularity of the current density allows islands to open quickly, but there is no singularity that allows a rapid closure. Islands remain and do not flutter into and out of existence. A relative rotation of the electron fluid in neighboring island chains produces a non-dissipative force that can lock the islands together and produce a non-ambipolar transport. At sufficient plasma pressure, the islands associated with different resonant rational surfaces can overlap. When this occurs some MAGNETic field lines will cross the entire radial region occupied by overlapping islands. The effect on the electron fluid is to create a viscosity-like force, which is dissipative and tends to remove gradients in the electron rotation. This also produces a non-ambipolar transport. Under many assumptions, the island locking force is larger than the viscosity-like force.

[abstract 24 / 41] (score: 2)
arXiv:2602.10328 [pdf, ps, other]

Title: Detecting HI Absorption in FRB Spectra: Modern Prospects and Scientific Utility

Authors: Hugh Roxburgh, Marcin Glowacki, Apurba Bera, Clancy James,

Comments: 10 pages, 4 figs, accepted in PASA

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

Created: 2026-06-18; Updated: 2026-06-19; Datestamp: 2026-06-19

Fast radio bursts (FRBs) emit broadband radio emission that may, in rare cases, encode atomic hydrogen (HI) absorption signals as they traverse the interstellar medium of their host galaxies. Though considered in the early FRB literature, the demanding observational prerequisites and the rarity of suitable events have meant that no thorough search for HI absorption in FRB spectra has yet been undertaken. Here, we present an updated systematic analysis assessing the likelihood of modern facilities to detect such absorption features. As a proof of concept, we search for absorption in the spectrum of the bright ASKAP-localised FRB 20211127I, finding a $3σ$ opacity upper limit of 0.51. While this test case offers little constraining power, we find that narrow FRBs with fluences exceeding 20/70/150 Jy ms observed with MeerKAT/ASKAP/DSA can probe opacities below 0.1 - a regime in which absorption detections become physically meaningful. We further highlight that stacking thousands of bursts from hyperactive repeaters with FAST offers a very powerful avenue toward detection. Finally, we discuss the broad scientific potential of such detections, including constraints on extragalactic HI spin temperatures, a means to physically probe the environment surrounding the progenitor, and a path towards disentangling host galaxy contributions to dispersion and scattering.

[abstract 25 / 41] (score: 2)
arXiv:2602.23429 [pdf, ps, other]

Title: Gravitational waves from primordial BLACK HOLEs passing by neutron stars: observational prospects for the Galactic center

Authors: Nicolas Esser, Juan García-Bellido, Peter Tinyakov,

Comments: Updated to match the version published in PRD

Subjects: astro-ph.HE

Created: 2026-06-18; Updated: 2026-06-19; Datestamp: 2026-06-19

We investigate the gravitational wave (GW) signals emitted by planetary-mass primordial BLACK HOLEs (PBHs) passing nearby or traversing neutron stars (NSs). While previous studies mainly focused on the detailed waveforms of the signals, we estimate the rate of PBH-NS gravitational-wave events originating from the Galactic center and compute the probability of detecting a signal over 10 years of LIGO-Virgo-KAGRA observations. We examine in detail the case of PBHs bound to NSs, focusing on eccentric orbits that give rise to repeated GW bursts emitted in correlated series, each burst corresponding to a periastron passage. Despite the enhancement from the large number of bursts produced by a single PBH-NS pair, the total number of signals produced in this way remains subdominant to those due to random unbound encounters of PBHs with NSs. We also find that both types of signals have a very small probability $P\lesssim 10^{-8}$ to be detected in a 10 year period.

[abstract 26 / 41] (score: 2)
arXiv:2604.15129 [pdf, ps, other]

Title: Las Cumbres Observatory Gravitational-Wave Follow-up in the Third and Fourth Observing Runs: Strengths and Weaknesses of a Rapid Response Galaxy Targeted Strategy

Authors: Ido Keinan, Iair Arcavi, D. Andrew Howell, Curtis McCully, Craig Pellegrino, Ayelet Hasson, Moira Andrews, Jamison Burke, Daichi Hiramatsu, Jennifer Barnes, Sukanya Chakrabarti, Joseph R. Farah, Paul J. Groot, Na'ama Hallakoun, Daniel Holz, Saurabh W. Jha, Daniel Kasen, Chris Lidman, Michael J. Lundquist, Dan Maoz, Brian D. Metzger, Ehud Nakar, Megan Newsome, Yuan Qi Ni, Alexander H. Nitz, Estefania Padilla Gonzalez, Tsvi Piran, Dovi Poznanski, Ryan Ridden-Harper, David J. Sand, Brian P. Schmidt, Giacomo Terreran, Brad E. Tucker, Stefano Valenti, J. Craig Wheeler, Samuel Wyatt, Kathryn Wynn,

Comments: Published in ApJ

Subjects: astro-ph.HE astro-ph.IM

Created: 2026-06-18; Updated: 2026-06-19; Datestamp: 2026-06-19

We present a summary of gravitational-wave (GW) follow-up using the Las Cumbres Observatory global network of telescopes during the third (O3) and fourth (O4) observing runs of the GW detectors. As in O2, we implemented the Gehrels et al. 2016 galaxy-targeted strategy. Here we test its efficacy in O3 and O4 and analyze the Las Cumbres Observatory response time and depth for nine GW alerts that showed a possibility of having an electroMAGNETic counterpart (GW190425, GW190426_152155, S190510g, GW190728_064510, GW190814, S190822c, GW191216_213338, S240422ed and S250206dm). We find that Las Cumbres Observatory is able to begin observations in response to GW alerts within minutes of the alert, with the observations being deep enough to detect possible GW170817-like kilonovae out to a median distance of 250 Mpc. In this sense a global rapid-response network of telescopes like Las Cumbres is an excellent GW follow-up facility. However, the galaxy-targeted follow-up strategy was much less efficient in O3 and O4 than originally predicted, given the larger than assumed GW localizations. We conclude that coordination between various facilities to include both wide-field and rapid-response capabilities is required to achieve efficient and comprehensive follow-up of GW events.

[abstract 27 / 41] (score: 2)
arXiv:2605.27953 [pdf, ps, other]

Title: Probing Effective Field Theory Corrections with Quasinormal Modes and Gravitational Lensing in Reissner-Nordström Black Holes

Authors: Takamasa Kanai,

Comments: 20 pages

Subjects: gr-qc hep-th

Created: 2026-06-18; Updated: 2026-06-19; Datestamp: 2026-06-19

Effective field theory (EFT) provides a systematic framework for parametrizing possible higher-energy corrections to general relativity through higher-curvature interactions. In this work, we investigate gravitational lensing in both weak- and strong-field regimes for EFT-corrected Reissner-Nordström BLACK HOLE spacetimes, focusing on both weakly charged and near-extremal configurations. Using the strong deflection limit formalism, we derive the corresponding corrections to the deflection angle, photon sphere radius, critical impact parameter, and strong lensing coefficients induced by higher-derivative curvature-electroMAGNETic interactions. Our analysis is restricted to purely geometrical corrections associated with modifications of the background spacetime geometry, without including POLARIZATION-dependent corrections to the photon propagation law. We show that strong gravitational lensing observables in charged BLACK HOLE backgrounds can provide complementary probes of effective interactions between gravity and electroMAGNETic fields. These results suggest that future high-precision observations of strong lensing phenomena may place constraints on higher-curvature EFT couplings beyond general relativity.

[abstract 28 / 41] (score: 2)
arXiv:2606.17141 [pdf, ps, other]

Title: Chemical enrichment of the Perseus cluster core seen by XRISM/Resolve

Authors: XRISM Collaboration, Marc Audard, Hisamitsu Awaki, Ralf Ballhausen, Aya Bamba, Ehud Behar, Rozenn Boissay-Malaquin, Laura Brenneman, Gregory V. Brown, Lia Corrales, Elisa Costantini, Renata Cumbee, Maria Diaz Trigo, Chris Done, Tadayasu Dotani, Ken Ebisawa, Megan E. Eckart, Dominique Eckert, Satoshi Eguchi, Teruaki Enoto, Yuichiro Ezoe, Adam Foster, Ryuichi Fujimoto, Yutaka Fujita, Yasushi Fukazawa, Kotaro Fukushima, Akihiro Furuzawa, Luigi Gallo, Javier A. García, Liyi Gu, Matteo Guainazzi, Kouichi Hagino, Kenji Hamaguchi, Isamu Hatsukade, Katsuhiro Hayashi, Takayuki Hayashi, Natalie Hell, Edmund Hodges-Kluck, Ann Hornschemeier, Yuto Ichinohe, Daiki Ishi, Manabu Ishida, Kumi Ishikawa, Yoshitaka Ishisaki, Jelle Kaastra, Timothy Kallman, Erin Kara, Satoru Katsuda, Yoshiaki Kanemaru, Richard Kelley, Caroline Kilbourne, Shunji Kitamoto, Shogo Kobayashi, Takayoshi Kohmura, Aya Kubota, Maurice Leutenegger, Michael Loewenstein, Yoshitomo Maeda, Maxim Markevitch, Hironori Matsumoto, Kyoko Matsushita, Dan McCammon, Brian McNamara, François Mernier, Eric D. Miller, Jon M. Miller, Ikuyuki Mitsuishi, Misaki Mizumoto, Tsunefumi Mizuno, Koji Mori, Koji Mukai, Hiroshi Murakami, Richard Mushotzky, Hiroshi Nakajima, Kazuhiro Nakazawa, Jan-Uwe Ness, Kumiko Nobukawa, Masayoshi Nobukawa, Hirofumi Noda, Hirokazu Odaka, Shoji Ogawa, Anna Ogorzałek, Takashi Okajima, Naomi Ota, Stephane Paltani, Robert Petre, Paul Plucinsky, Frederick S. Porter, Katja Pottschmidt, Kosuke Sato, Toshiki Sato, Makoto Sawada, Hiromi Seta, Megumi Shidatsu, Aurora Simionescu, Randall Smith, Hiromasa Suzuki, Andrew Szymkowiak, Hiromitsu Takahashi, Mai Takeo, Toru Tamagawa, Keisuke Tamura, Takaaki Tanaka, Atsushi Tanimoto, Makoto Tashiro, Yukikatsu Terada, Yuichi Terashima, Yohko Tsuboi, Masahiro Tsujimoto, Hiroshi Tsunemi, Takeshi Tsuru, Ayşegül Tümer, Hiroyuki Uchida, Nagomi Uchida, Yuusuke Uchida, Hideki Uchiyama, Shutaro Ueda, Yoshihiro Ueda, Shinichiro Uno, Jacco Vink, Shin Watanabe, Brian J. Williams, Satoshi Yamada, Shinya Yamada, Hiroya Yamaguchi, Kazutaka Yamaoka, Noriko Yamasaki, Makoto Yamauchi, Shigeo Yamauchi, Tahir Yaqoob, Tomokage Yoneyama, Tessei Yoshida, Mihoko Yukita, Irina Zhuravleva, Elena Bellomi, Ian Drury, Annie Heinrich, Julie Hlavacek-Larrondo, Julian Meunier, Konstantinos Migkas, Lior Shefler, Phillip C. Stancil, Nhut Truong, Benjamin Vigneron, Congyao Zhang, John ZuHone,

Comments: 16 pages, 10 figures. Accepted for publication in Astronomy & Astrophysics

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

Created: 2026-06-18; Updated: 2026-06-19; Datestamp: 2026-06-19

The intracluster medium (ICM) is rich in chemical elements, produced by core-collapse (SNcc) and Type Ia SUPERNOVAe (SNIa) over the last $\sim$12 Gyr. Whereas cluster outskirts are uniformly enriched with Fe at $\sim$0.3 solar - strongly suggesting that the gas had been pre-enriched during or before the assembly of galaxies into clusters, the Fe abundance is known to centrally increase in the core of relaxed clusters. The origin of these central Fe peaks however, as well as the apparent presence of mysterious drops previously reported in the very centre of a number of systems, remain to be clarified. In this paper, we address these two questions by measuring the spatial distribution of Fe and its relative Si/Fe, S/Fe, Ar/Fe, Ca/Fe, Cr/Fe, Mn/Fe, and Ni/Fe ratios in the X-ray bright, nearby Perseus cluster. We take advantage of the unprecedented spectral resolution ($\sim$5 eV) offered by the Resolve microcalorimeter on board XRISM, which observed four distinct pointings of Perseus out to $\sim$250 kpc ($\sim$0.2$r_{500}$) during its Performance Verification phase. Although the presence of an X-ray bright AGN challenges a precise quantification of absolute abundances in the very core, our baseline analysis rules out a strong drop with $>$2$σ$ confidence, at variance with previous CCD measurements. In addition, we find a remarkable spatial uniformity of X/Fe ratios, supporting the idea of negligible late SNIa enrichment from the brightest cluster galaxy NGC 1275. We also compare the overall chemical composition of the Perseus ICM with SNcc and SNIa nucleosynthesis yield models, finding that the co-existence of two separate SNIa enrichment channels is not needed to reproduce the ICM ratios satisfactorily.

[abstract 29 / 41] (score: 2)
arXiv:2606.19449 [pdf, ps, other]

Title: A self-consistent analytical model for both the photoionization rate and reionization history

Authors: Christopher Cain, Kevin S. Croker, Anson D'Aloisio, Ivelin Georgiev, Hurum Maksora Tohfa, Yongda Zhu, Rogier Windhorst,

Comments: 22 pages, 8 figures (main text) + 4 pages (appendices). Prepared for submission to JCAP. Comments welcome!

Subjects: astro-ph.CO astro-ph.GA

Created: 2026-06-17; Updated: 2026-06-19; Datestamp: 2026-06-19

Recent developments at the intersection of cosmology and astrophysics have highlighted the need for improved analytical models of observables that probe the Epoch of Reionization. With few exceptions, fast analytical treatments of reionization suitable for use in Bayesian inference have been limited to modeling the reionization history, $x_i(z)$. Such models cannot take full advantage of observables that constrain $x_i$ indirectly. One such observable is the photoionization rate of neutral hydrogen, $Γ_{\rm HI}(z)$, which can be inferred from the mean transmission of the Lyman-$α$ forest of high-redshift QUASARs and galaxies. It has been shown by several prior works that the evolution of $Γ_{\rm HI}$ at $5 \lesssim z \lesssim 6$ is highly sensitive to the tail end of reionization, potentially providing a tight astrophysical constraint on the reionization timeline. We present a new analytical formalism, based on the cosmological radiative transfer equation, that self-consistently predicts $x_i$ and $Γ_{\rm HI}$. We test our model against detailed radiative transfer simulations and find it to be percent-level accurate in $x_i$ and $20-30\%$ accurate in $Γ_{\rm HI}$ at $z \lesssim 6$ - better than or comparable to existing observational uncertainties. Finally, we demonstrate that modest shifts in the ionizing photon output of high-redshift galaxies and/or the endpoint of reionization lead to differences in $Γ_{\rm HI}$ much larger that the model's intrinsic uncertainty, highlighting its utility for interpreting existing data. We explore the origin of modeling uncertainty in $Γ_{\rm HI}$ and comment on future pathways for improvement.

[abstract 30 / 41] (score: 2)
arXiv:2606.19459 [pdf, ps, other]

Title: Fireworks at Cosmic Dawn: relieving BAO-CMB tensions with the Pop III.1 Flash

Authors: Yash Aggarwal, Christopher Cain, Garett Lopez, Hy Trac, Anson D'Aloisio, Philip Tanedo, Jonathan C. Tan,

Comments: 12 pages, 5 figures. Submitted to ApJL, comments welcome

Subjects: astro-ph.CO astro-ph.GA

Created: 2026-06-17; Updated: 2026-06-19; Datestamp: 2026-06-19

A Cosmic Microwave Background (CMB) optical depth of $τ\sim 0.09$, several $σ$ in excess of the latest Planck low-$\ell$ EE POLARIZATION measurement, has been proposed as a way to reconcile the preference for a sub-minimal neutrino mass sum in a combined analysis with CMB and Dark Energy Spectroscopic Instrument (DESI) three-year data. Reionization, however, is not just probed by $τ$. It is also constrained by Ly$α$ forest observations that indicate a late end of reionization, and the patchy kinetic Sunyaev-Zel'dovich (pkSZ) effect which prefers a short duration. We explore whether an early phase of reionization can achieve a high $τ$ while remaining consistent with both Ly$α$ forest and pkSZ constraints. As a concrete example, we consider supermassive Pop III.1 stars, dark-matter-powered metal-free stars proposed as progenitors of supermassive BLACK HOLEs. Within this framework, self-regulating ionizing feedback imposes a minimum source separation of $\sim 1 \, \text{cMpc}$, consequently limiting large-scale ionization fluctuations and reducing the pkSZ power on observationally relevant scales. Our fiducial model realizes an optical depth of $τ= 0.087$ with a Pop III.1-driven flash ionization phase centered at $z = 20$, while evading the most conservative $2σ$ upper limits on the pkSZ signal from the most recent South Pole Telescope data release. More broadly, our findings motivate further exploration of early reionization models with weakly clustered sources as a possible resolution of tensions between BAO and CMB measurements.

[abstract 31 / 41] (score: 2)
arXiv:2606.19523 [pdf, ps, other]

Title: Bayesian optimization of stellarator alpha-particle confinement using data-informed parameter spaces and dimensionality reduction

Authors: Matt Landreman, Michael Czekanski, Andrew Giuliani, Byoungchan Jang, Rory Conlin,

Comments:

Subjects: physics.plasm-ph

Created: 2026-06-17; Updated: 2026-06-19; Datestamp: 2026-06-19

Modern stellarators are typically designed by optimizing the shape of the plasma boundary surface, with the parameters taken to be Fourier amplitudes. Many promising optimization algorithms such as Bayesian methods require bound constraints on the parameters and are most efficient when each parameter is scaled similarly to the others. With the typical Fourier parameterization, it is unclear how to set these bounds: wide constraints lead to self-intersecting boundaries and frequent failures of the MHD equilibrium calculation, while tight bound constraints limit expressiveness. To address these issues, here we propose two new parameter spaces for stellarator optimization. Both begin with a dataset of existing stellarator boundaries. In the first approach, a quantile transformation is applied to each Fourier degree of freedom, mapping the data distribution to a uniform distribution on the unit interval. In the second approach, principal component analysis (PCA) is applied to points on the boundaries, followed by a quantile transformation. For both approaches, the transformed variables become the degrees of freedom, naturally bounded to [0, 1]. The PCA method has the additional benefit of dimensionality reduction, with high expressiveness for a small number of parameters. The methods are demonstrated via Bayesian optimization for good alpha-particle confinement with guiding-center tracing inside the optimization loop, using asynchronous parallelization. These optimizations yield stellarator configurations with excellent fast-particle confinement in fields that can be far from quasisymmetric or quasi-isodynamic.

[abstract 32 / 41] (score: 2)
arXiv:2606.19701 [pdf, ps, other]

Title: On the Contribution of Local Sources to the Galactic Cosmic-Ray Spectrum: An Exact Series Solution for Two-Zone Diffusion

Authors: Zi-Hang Liu, Yiwei Bao, Ruo-Yu Liu,

Comments: submitted to PRD, The code accompanying this paper will be released soon

Subjects: astro-ph.HE

Created: 2026-06-18; Updated: 2026-06-19; Datestamp: 2026-06-19

Measurements of cosmic-ray proton and helium spectra below the knee show deviations from simple power laws, including multi-TeV structures. A possible explanation is that one or a few nearby sources contribute an additional component to the local spectrum. However, previous study shows that a dominant local contribution is statistically unlikely under a homogeneous diffusion model. In this work, we investigate how this probability changes if COSMIC RAYs experience inefficient transport near their sources, motivated by observations of extended gamma-ray emission around Galactic accelerators. We derive a series Green's function that enables fast calculation of the particle distribution in this scenario, making Monte Carlo calculations for Galactic source populations feasible. The inner slow-diffusion region delays escape and redistributes the arriving particles in time and energy. In Monte Carlo realizations, the probability that the strongest local source becomes comparable to the background at $10\,\rm{TeV}$ increases from about $0.4\%$ in homogeneous diffusion to $1.7$--$2.2\%$ in the two-zone models. Thus inhibited near-source transport weakens, but does not remove, the statistical difficulty. We then examine cataloged nearby candidate SUPERNOVA remnants and show that a $10\,\rm{TeV}$ feature can be reproduced only with additional assumptions, especially a harder local injection spectrum and a favorable diffusion coefficient. The predicted contribution of a given source changes strongly among different particle transport model. Therefore, the local source interpretations are plausible but highly model dependent, and require independent constraints on source injection history, particle transport mechanisms, and local interstellar turbulence.

[abstract 33 / 41] (score: 2)
arXiv:2606.19856 [pdf, ps, other]

Title: On the braking index evolution of PSR B0540-69: wind braking of pulsars

Authors: H. Tong,

Comments: 6 pages, 1 figure. submitted

Subjects: astro-ph.HE

Created: 2026-06-18; Updated: 2026-06-19; Datestamp: 2026-06-19

The pulsar PSR B0450-69 has both a braking index measurement and spin-down state change. After its spin-down state change, it shows an increasing braking index with time. Previously, it is pointed out that the spin-down state change may be caused by an enhanced particle wind. The prediction is that its braking index in the high spin-down state will be smaller. The current measured braking index is approaching the previous prediction. The transient variation of braking index may be due to a small varying part of the particle number density. The final braking index evolution is found to be in an exponential form. The braking index of PSR B0540-69 is expected to approach some steady value. Future braking index measurement may make clear the physics for the braking index evolution. It may also help to make test different particle acceleration potential in the pulsar MAGNETosphere. Finally, a phenomenological treatment of wind braking model of pulsars is presented. It can simplify the applications to pulsar braking index, intermittent pulsars and PSR B0540-69.

[abstract 34 / 41] (score: 2)
arXiv:2606.19979 [pdf, ps, other]

Title: Supernova Remnants in the IXPE era: a review

Authors: Riccardo Ferrazzoli, IXPE Collaboration,

Comments: To be published in the Multifrequency Behaviour of High Energy Cosmic Sources - XV Proceedings of Science 2025 issue: https://pos.sissa.it/506/

Subjects: astro-ph.HE

Created: 2026-06-18; Updated: 2026-06-19; Datestamp: 2026-06-19

The Imaging X-ray Polarimetry Explorer (IXPE) has opened a new observational window on the physics of SUPERNOVA remnants (SNRs) by providing the first spatially resolved X-ray polarimetry measurements. These data directly probe the geometry and turbulence of MAGNETic fields in regions of efficient particle acceleration, thereby constraining models of diffusive shock acceleration and MAGNETic-field amplification. IXPE has so far observed six young SNRs (Cas A, Tycho, SN 1006, RX J1713.7-3946, Vela Jr., and RCW 86) with published results on the first five. The observations reveal significant POLARIZATION in all cases, with degrees of POLARIZATION ranging from 5% to over 30%, reflecting different turbulence levels and environmental conditions. Three remnants (Cas A, Tycho, and SN 1006) show predominantly radial MAGNETic fields, while RX J1713.7-3946 and Vela Jr. display tangential morphologies. This dual behavior, not simply correlated with evolutionary stage, challenges the long-standing dichotomy inferred from radio observations and suggests that both shock velocity and circumstellar medium density play key roles in shaping MAGNETic-field topology. IXPE's results mark a major step toward disentangling the processes governing cosmic-ray acceleration in young SNR shocks, with ongoing and future observations expected to further constrain the interplay between turbulence, shock dynamics, and particle acceleration.

[abstract 35 / 41] (score: 2)
arXiv:2606.20019 [pdf, ps, other]

Title: Once more: Leaky MHD waves in coronal MAGNETic flux tubes

Authors: Hans Goedbloed, Rony Keppens,

Comments: accepted for JPP, to appear

Subjects: astro-ph.SR math-ph math.MP physics.plasm-ph

Created: 2026-06-18; Updated: 2026-06-19; Datestamp: 2026-06-19

By a detailed comparison of leaky MAGNETohydrodynamic waves in coronal MAGNETic flux tubes with leaky electroMAGNETic waves in dielectric media it is shown that the latter kind may be called quasi-normal modes, since they can be regularised by a normalisation which systematically cuts off the contribution of the external homogeneous region, whereas such a possibility is forbidden for the former kind by the conservation of MAGNETic flux. Consequently, leaky MAGNETohydrodynamic waves cannot be systematically applied to coronal seismology, i.e. to the inverse spectral problem of determining the different equilibrium distributions of the fields by comparing the spectra they produce with the observed ones.

[abstract 36 / 41] (score: 2)
arXiv:2606.20021 [pdf, ps, other]

Title: A Whisper from Within: Response of a Pulsar Timing Array to an Internal Gravitational-wave Source

Authors: Houyuan Qi, Xian Chen, Lin Wang, Kuo Liu,

Comments: 15 pages, 9 figures

Subjects: astro-ph.HE

Created: 2026-06-18; Updated: 2026-06-19; Datestamp: 2026-06-19

Millisecond pulsars (MSPs) are abundant in globular clusters (GCs) and probably also in galactic nuclei. They offer the potential to form a miniature pulsar timing array (mini-PTA) to detect nanohertz gravitational-wave (GW) sources located inside the array. Since the size of such an array is comparable to the wavelength of GW, the conventional plane-wave approximation becomes invalid, and near-field effects, including wavefront curvature, non-radiative self-field of the GW source, and direct perturbation of pulsar by GW, become significant. In this work, we incorporate these effects in a comprehensive model to calculate the timing residual induced by a GW source inside a mini-PTA. We also consider realistic GW source configurations in GCs (M15 and $ω$ Centauri) and in galactic nuclei (Sgr A* and M31), and find that for MSPs located sufficiently close to the GW source (within a few wavelengths), the residual can reach $1~μ\mathrm{s}$ in GCs and up to milliseconds in galactic centers, within the potential detection reach of current radio telescopes. Crucially, when the pulsar lies within a few GW wavelengths of the source, the non-radiative field dominates and causes the residual to rise much more steeply (between $1/r_e^2$ and $1/r_e^4$, where $r_e$ is the distance to the source) than the conventional far-field scaling ($1/r_e$). These results demonstrate that mini-PTAs in GCs or galactic nuclei can serve as powerful probes of otherwise invisible GW sources, including intermediate-mass and supermassive BLACK HOLE binaries.

[abstract 37 / 41] (score: 2)
arXiv:2606.20061 [pdf, ps, other]

Title: Modification of JET-energy flow in heavy-ion collisions

Authors: ALICE Collaboration,

Comments: 24 pages, 7 captioned figures, 3 tables, authors from page 19, submitted to PPP, figures at http://alice-publications.web.cern.ch/node/13376

Subjects: nucl-ex

Created: 2026-06-18; Updated: 2026-06-19; Datestamp: 2026-06-19

The ALICE Collaboration presents the first measurements of the JET-energy flow ($Δp_{\rm T}$) observable in proton-proton and heavy-ion collisions. Jets are excellent probes for the QUARK$-$gluon plasma, a deconfined state of matter produced in heavy-ion collisions. The JET-energy flow observable characterizes the radial distribution of energy from the JET axis in an infrared and collinear-safe way and is sensitive to medium-induced parton-shower modifications. Inclusive charged JETs are measured in Pb$-$Pb collisions at $\sqrt{s_{\rm NN}} = 5.02$ TeV for the transverse-momentum interval 60$-$80 GeV/$c$. For pp collisions at $\sqrt{s}=13$ TeV, measurements include the 40$-$60 and 60$-$80 GeV/$c$ intervals, where the latter serves as the reference for investigating medium-induced modifications. Results show that most parton energy is concentrated in the JET core, with a clear suppression of energy flow in heavy-ion collisions at larger radii (significance 3.5$-$4.5$σ$) indicating a narrowing of the energy flow. While all models -- PYTHIA 8, HERWIG, JEWEL, and JETSCAPE -- reproduce the pp results with only small deviations in the tails, the relative modification in Pb$-$Pb collisions is well described by JEWEL without recoil. Conversely, JEWEL with recoil (medium response) and JETSCAPE show significant deviations, exhibiting increasing or more constant trends with radius that are disfavored by the data.

[abstract 38 / 41] (score: 2)
arXiv:2606.20086 [pdf, ps, other]

Title: A FAST search for radio pulsations during the dormant state of the AMSPs IGR J00291+5934 and MAXI J1957+032

Authors: A. Marino, E. Parent, F. Coti Zelati, M. C. Baglio, A. Papitto, A. Sanna, A. Anitra, C. Kazantsev, N. Rea, A. Borghese, L. Burderi, T. Di Salvo, C. Espinoza, X. Hou, R. Iaria, G. Illiano, D. M. Russell, R. Sathyaprakash,

Comments: 10 pages, 2 figures; accepted for publication by A&A

Subjects: astro-ph.HE

Created: 2026-06-18; Updated: 2026-06-19; Datestamp: 2026-06-19

Accreting millisecond pulsars (AMSPs) and transitional millisecond pulsars (tMSPs) are neutron star low-mass X-ray binaries which can evolve into "recycled" radio millisecond pulsars. In both types of systems, X-ray pulsations have been detected during phases of X-ray activity when matter accretion through a disc is turned on. On the other hand, when accretion stops, and these systems enter the quiescent, low-luminosity X-ray state, only tMSPs become visible as radio pulsars. Despite several attempts, radio pulsations have never been detected in quiescent AMSPs, except for IGR J18245$-$2452. In this manuscript, we present the results of two observational campaigns performed on the AMSPs IGR J00291+5934 and MAXI J1957+032 with the Five-hundred-meter Aperture Spherical Telescope ($\it{FAST}$) in L-band (1-1.5 GHz). Both sources have most likely been observed in quiescence, as suggested by the upper limits on their X-ray and optical flux obtained with SWIFT and the Las Cumbres Observatory, respectively. We have performed a deep search for coherent periodicities in radio but found no significant candidate signal, either at the known spin frequency of those sources or at other frequencies. Assuming a pulse duty cycle of 10%, we derive upper limits on the pulsed radio flux density of 3.3 $μ$Jy and 5.6 $μ$Jy for IGR J00291+5934 and MAXI J1957+032, respectively, which are the most stringent limits so far for any known persistent AMSP.

[abstract 39 / 41] (score: 2)
arXiv:2606.20201 [pdf, ps, other]

Title: Kick bimodality of neutron stars and mode dependence of their parameters

Authors: Anton D. Lazarev, Sergei B. Popov,

Comments: 13 pages, 7 figures. Submitted to Ap&SS

Subjects: astro-ph.HE

Created: 2026-06-18; Updated: 2026-06-19; Datestamp: 2026-06-19

Analysis of observational data and theoretical modeling favors a bimodal distribution of the natal velocity kick of neutron stars. For $\sim200$ normal isolated radio pulsars with well-determined spin and kinematic parameters, we determine if they belong to the low- or high-velocity mode of the distribution. Our results demonstrate that about $30\%$ belong to the low-velocity mode. We then analyze the differences in the properties of the two sets of pulsars. For some parameters (characteristic ages, distances, and radio luminosities), we see a clear difference between the two modes. However, for these quantities, it can be easily attributed to selection bias. For those parameters that are not a subject of strong selection, such as pulse width, we do not observe any difference. Interestingly, we detect a significant difference in the MAGNETic field distribution between the two modes. Lower field pulsars ($B\lesssim 10^{12}$~G) are overabundant among objects from the low-velocity mode in comparison to the high-velocity one. Among pulsars with low field ($\lesssim 10^{11}$~G), we do not identify any objects from the high-velocity mode of the kick distribution. The origin of this discrepancy is not clear, and we discuss several possibilities.

[abstract 40 / 41] (score: 2)
arXiv:2606.20284 [pdf, ps, other]

Title: Constitutive birefringence and critical curves in the rotating García--Díaz BLACK HOLE

Authors: Ariel Guzmán, Mohsen Fathi, J. R. Villanueva,

Comments: 26 pages, 2 figures, 3 tables

Subjects: gr-qc astro-ph.HE hep-th math-ph math.MP

Created: 2026-06-18; Updated: 2026-06-19; Datestamp: 2026-06-19

We study high-frequency electroMAGNETic propagation in the rotating García--Díaz solution of Einstein gravity coupled to NLED. In this system, light is not governed only by the null cone of the spacetime metric, because the NLED field also behaves as an optical medium whose constitutive response determines the physical optical cones. Starting from the mixed electroMAGNETic potentials, we project the field $F$ and the excitation $P$ on a principal tetrad and obtain the aligned scalars $E$, $B$, $D$ and $H$. These scalars allow us to reconstruct the regular local constitutive branch connected with Maxwell theory through the map $(D,B)\mapsto(E,H)$. We then insert the resulting response matrix into the Fresnel characteristic problem. At the perturbative order considered here, the Fresnel quartic factorizes into two quadratic branches, each defining an effective optical metric. Both optical metrics admit Carter-type separation of the Hamilton--Jacobi equation and possess their own radial and angular potentials, critical constants and unstable critical families. By projecting these families onto the celestial sphere of a finite-distance observer, we obtain two critical contours, $Γ_+$ and $Γ_-$, which coincide in the Maxwell limit and split when the nonlinear constitutive response is active. We quantify this birefringent splitting through the maximum angular separation, the relative diameter shift and the normalized birefringent width. Numerical scans over the nonlinear coupling, spin and observer inclination show that the splitting is generated by the constitutive response, redistributed by rotation and stable under local projection changes within the perturbative domain. This provides a direct geometrical link between the local NLED response and a POLARIZATION-dependent critical structure on the observer screen.

[abstract 41 / 41] (score: 2)
arXiv:2606.20555 [pdf, ps, other]

Title: Incorporating physical source parameters into microlensing modeling

Authors: Mateusz J. Mróz, Radosław Poleski, Andrzej Udalski, Jan Skowron, Paweł Pietrukowicz, Michał K. Szymański, Przemek Mróz, Mariusz Gromadzki, Patryk Iwanek, Szymon Kozłowski, Milena Ratajczak, Krzysztof A. Rybicki, Dorota M. Skowron, Igor Soszyński, Krzysztof Ulaczyk, Marcin Wrona, Zofia Buzik,

Comments: 15 pages, 6 figures

Subjects: astro-ph.SR astro-ph.IM

Created: 2026-06-18; Updated: 2026-06-19; Datestamp: 2026-06-19

Modeling of complex microlensing events suffers from many difficult-to-disentangle degeneracies. This is especially the case for orbital motion of the source in a binary system, the so-called xallarap effect. To address the degeneracies inherent in xallarap modeling, we developed a novel approach that directly samples the physical parameters of the source stars (initial mass, evolutionary phase, metallicity, distance, and reddening) during MCMC fitting. In our approach the physical parameters of the source are estimated using MIST stellar evolution models. This parametrization imposes astrophysical constraints that help identify the physically most probable solutions. We test our method on the complex microlensing event OGLE-2017-BLG-0114, which exhibits signatures that can be traced to the complexity of the source system. We successfully constrained the microlensing models, achieving improvements in the Einstein ring radius estimates by up to an order of magnitude in the case of binary source models.