Current date: 2026-07-07
Setting default datestamp limit: 0
Datestamp limit: 2026-07-07 (0 days ago)
Created/updated limit: 2026-06-30 (7 days ago)
Found keywords_cs.datFound keywords_cis.dat
Suggested sets: physics, physics:astro-ph, physics:gr-qc, physics:physics
Setting default set: physics
OAI-PMH request: http://export.arxiv.org/oai2?verb=ListRecords&from=2026-07-07&until=2026-07-07&set=physics&metadataPrefix=arXiv
Scoring abstracts
Number of records retrieved: 1300
Keyword score statistics
score 10 -- 2 abstracts
score 8 -- 4 abstracts
score 7 -- 5 abstracts
score 6 -- 4 abstracts
score 5 -- 6 abstracts
score 4 -- 10 abstracts
score 3 -- 15 abstracts
score 2 -- 46 abstracts
in total -- 92 abstracts
Articles that appeared on 2026-07-07
-
[abstract 1 / 92] Wow! (score: 10)
- Title: Investigating the Temporal Evolution of Gamma-Ray Burst Central Engine Parameters Based on Numerical SimulationsAuthors: Wei-Hua Lei,Comments: 12 pages, 5 figures,accepted for publication in Journal of High Energy AstrophysicsSubjects: astro-ph.HECreated: 2026-07-04; Updated: 2026-07-07; Datestamp: 2026-07-07
A hyperaccreting stellar-mass BLACK HOLE (BH) has been proposed as the candidate central engine of GAMMA-RAY BURSTs (GRBs). Comparing the predictions from the central engine models with the temporal behavior of GRBs is of great interest. In this paper, using the open-source GRMHD HARM-COOL code, we evolve several 2D MAGNETized hyperaccreting BH models with realistic equation of state in a fixed curved space-time background. We extend the code to include the calculation of neutrino annihilation power. We then study the time evolution of BH central engine parameters, i.e., the neutrino annihilation power, the Blandford-Znajke (BZ) power, and the initial MAGNETization $σ_0$. We find that the neutrino power is generally consistent with previous analytical results. Usually, the neutrino annihilation process tends to launch a thermal ``fireball'', while the BZ JET is Poynting-flux-dominated. Our results, especially the evolution characteristics of $σ_0$ may help to understand the complex GRB spectral behavior.
[abstract 2 / 92] Wow! (score: 10) - Title: Observational Study of Multi-wavelength Synergistic Effects in 3C 120Authors: Yuting He, Ming Zhang, Qi Yuan, Nenghui Liao,Comments: 20 pages, 12 figures, 3 tables. Accepted for publication in ApJSubjects: astro-ph.GA astro-ph.HECreated: 2026-07-06; Updated: 2026-07-07; Datestamp: 2026-07-07
The energy dissipation and particle acceleration mechanisms within RELATIVISTIC JETs remain fundamental questions in ACTIVE GALACTIC NUCLEi (AGN) research. In this paper, we present a comprehensive 13-year (2012-2025) multi-wavelength study of the broad-line RADIO GALAXy 3C 120, utilizing FERMI-LAT ($γ$-ray), ASAS-SN (optical), and high-resolution VLBA (15 GHz and 43 GHz) monitoring. Cross-correlation analyses reveal that $γ$-ray flares lead radio emission by $11.08_{-1.88}^{+4.03}$ months at 15 GHz and $8.27_{-5.55}^{+3.45}$ months at 43 GHz. This frequency-dependent temporal hierarchy positions the high-energy dissipation zone upstream of the radio core, corroborating the opacity-driven core-shift effect. By tracking the parsec-scale JET morphology during major $γ$-ray flaring epochs, we demonstrate that radio outbursts systematically coincide with compact core brightening, pronounced surges in polarized flux, abrupt electric vector position angle rotations, and the subsequent ejection of superluminal knots. Ultimately, our internal radio correlations suggest that JET dynamics are governed by a dual mechanism: long-term kinematic and flux baseline variations are geometrically modulated by a secular JET precession, while rapid, highly energetic polarimetric bursts are driven by short-lived internal shocks propagating down the JET channel.
[abstract 3 / 92] Wow! (score: 8) - Title: Constraining Disk-to-Corona Power Transfer Fraction, Soft X-ray Excess Origin, and Black Hole Spin Population of Type-1 AGN across Mass ScalesAuthors: Labani Mallick, Ciro Pinto, John Tomsick, Alex Markowitz, Andrew Fabian, Samar Safi-Harb, James Steiner, Fabio Pacucci, William Alston,Comments: 49 pages, 16 figures, 3 tables, 7 supplementary tables, and 5 supplementary figures in the Appendix. Accepted for publication in Physical Review D (PRD)Subjects: astro-ph.HE astro-ph.GA physics.space-phCreated: 2026-07-04; Updated: 2026-07-07; Datestamp: 2026-07-07
Understanding the nature of the accretion disk, its interplay with the X-ray corona, and assessing BLACK HOLE spin demographics remain open challenges in astrophysics. In this paper, we examine the predictions of the standard $α$-disk model, origin of the puzzling soft X-ray excess, and measure the BLACK HOLE spin parameter by applying an updated high-density disk reflection model to the XMM-Newton/NUSTAR broadband (0.3$-$78 keV) X-ray spectra of a sample of 11 Type-1 AGN. Our Bayesian analysis confirms that a variable-density RELATIVISTIC disk reflection model with a broken power-law emissivity profile can simultaneously fit the soft X-ray excess, broad iron K line emission, and Compton hump in 3 out of 11 AGN. For the remaining sources, a distinct warm Comptonization component is still required, which supports a hybrid origin for the soft X-ray excess. The measured temperature and optical depth of the warm corona span nearly the entire theoretically allowed range, with median values of $0.43_{-0.18}^{+0.40}$ keV and $12.5_{-3.9}^{+3.1}$, respectively. Our first systematic calculation of the disk-to-corona power transfer fraction reveals that the fraction of power released from the accretion disk into the hot corona spans a wide range, with a sample median of $0.68_{-0.25}^{+0.25}$. The sample median values for the hot coronal plasma temperature and optical depth are $54_{-12}^{+11}$ keV and $0.98_{-0.28}^{+0.22}$, respectively. Finally, through both hard X-ray (3$-$78 keV) and broadband (0.3$-$78 keV) RELATIVISTIC reflection spectroscopy, we systematically constrain the BLACK HOLE spin parameter across the mass scales of $\log(M_{\rm BH}/M_{\odot}) \sim 5.5-9.0$, thereby increasing or refining the available spin measurements in the AGN population by $\sim$20%.
[abstract 4 / 92] Wow! (score: 8) - Title: A Shock-based Interpretation of Radio and X-ray Emission in Active Galactic NucleiAuthors: Fan Wu, Benzhong Dai,Comments: Accepted for publication in APJ. 15 pages, 3 figures, 3 tablesSubjects: astro-ph.HE hep-phCreated: 2026-07-02; Updated: 2026-07-07; Datestamp: 2026-07-07
We propose a shock-based framework to interpret the radio and X-ray emission in ACTIVE GALACTIC NUCLEi (AGNs), whose origin remains an open problem. In this framework, the radio emission is produced by SYNCHROTRON radiation in the accretion flow or a JET/weak outflow, while the dominant X-ray component depends on the accretion state, the location of the non-thermal emission region, and the available seed photon field. The model provides a self-consistent interpretation of radio and X-ray emission in typical non-JETted AGNs, including low-luminosity AGNs, Seyfert galaxies, and radio-quiet QUASARs. In JETted AGNs, our results disfavor scenarios in which the non-thermal electrons responsible for X-ray emission are accelerated in the disk or the corona. We use two widely discussed empirical diagnostics, radio loudness and the fundamental plane (FP) of BLACK HOLE (BH) activity, to assess the applicability and limitations of the model. It can naturally explain the observed trends that the radio loudness increases with BH mass and decreases with the Eddington ratio. The observed slope of the FP depends on how the key physical quantities scale with the accretion rate. As the accretion rate increases, the advection-dominated accretion flow region contracts while the thin disk region expands, reflecting a transition toward a more radiatively efficient accretion structure. The Eddington ratio therefore influences the accretion structure, and may in turn shape the observed AGN classes.
[abstract 5 / 92] Wow! (score: 8) - Title: Neutrinos from super-Eddington Seyfert galaxiesAuthors: Lucas M. Pasquevich, Gustavo E. Romero, Matías M. Reynoso,Comments: Under review for minor corrections in Astroparticle PhysicsSubjects: astro-ph.HECreated: 2026-07-03; Updated: 2026-07-07; Datestamp: 2026-07-07
Multimessenger observations suggest that Seyfert galaxies are promising sources of high-energy neutrinos, but their dense inner environments can strongly suppress the emerging very-high-energy gamma-ray emission. Active galactic nuclei (AGN) undergoing intense accretion episodes can enter a super-Eddington state, in which the accretion flow becomes geometrically and optically thick within a critical radius and develops strong MAGNETic fields in its innermost region. At the same time, large amounts of matter are expelled from the disk surface in the form of powerful, radiation-driven winds. In this work, we explore a scenario in which the cores of super-Eddington AGN provide suitable conditions for the acceleration of RELATIVISTIC particles, including hadrons, via MAGNETic RECONNECTion in a MAGNETically confined region close to the supermassive BLACK HOLE. The accelerated hadronic component interacts with the intense photon field of the disk, leading to a copious neutrino flux peaking at 10-100 TeV that may be detectable with current observatories such as IceCube and KM3NeT, while the surrounding outflow efficiently absorbs the accompanying gamma-ray emission from the inner core. We also apply the model to the nearby super-Eddington Seyfert 1 NGC 7469 as a representative case with two reported neutrino events. In this framework, super-Eddington AGN, in particular Seyfert galaxies undergoing transient intense accretion episodes, emerge as plausible hidden neutrino sources, offering a natural explanation for the coexistence of efficient neutrino production and a strongly attenuated gamma-ray counterpart.
[abstract 6 / 92] Wow! (score: 8) - Title: Different dissipation mechanisms of JET underlying variability in BLAZARsAuthors: Hong-bin Tan, Ruo-yu Liu,Comments: 18 pages, 9 figuresSubjects: astro-ph.HECreated: 2026-07-04; Updated: 2026-07-07; Datestamp: 2026-07-07
Blazars are among the most extreme classes of ACTIVE GALACTIC NUCLEi. They are powered by RELATIVISTIC JETs, but the way in which the JET energy is dissipated is still unclear. The flat radio spectrum and the core-shift effect trace the distributions of MAGNETic fields and RELATIVISTIC particles along the JET, while variability carries information about time-dependent dissipation. However, a unified framework connecting these observables to the underlying JET physics has been lacking. Here we present a multi-frequency analysis of the prototypical BLAZAR Mrk~501. We model its core-shift measurements, spectral energy distributions (SEDs), and power spectral densities (PSDs) with a conical JET model that conserves MAGNETic power. The core-shift data localize the radio emitting regions and constrain the electron-density and dissipation-rate profiles along the JET. With a single radial distribution of JET parameters, the model reproduces the core-shift relation and SED, but it underpredicts the observed variability at high radio frequencies and in the optical to $γ$-ray bands. We therefore introduce different blob distributions for the inner ($\lesssim$~0.1\,pc) and outer ($\gtrsim$~0.1\,pc) JET regions. With this extended model, the simulated PSDs are consistent with the multiwavelength observations of Mrk~501 during its 2017--2019 low state. This result points to different dissipation behavior in the inner and outer JET. Our study demonstrates that spectro--timing--astrometric JET modeling, which combines SEDs, multiwavelength PSDs, and radio core-shift measurements, can constrain JET stratification and scale-dependent dissipation in BLAZARs.
[abstract 7 / 92] Wow! (score: 7) - Title: X-ray POLARIZATION in the soft state of Cyg X-1Authors: A. Niedzwiecki, M. Szanecki, A. Veledina, A. A. Zdziarski, A. Chakraborty, J. Poutanen, P. Lubinski, A. Salganik,Comments: 13 pages, A&A, in pressSubjects: astro-ph.HECreated: 2026-07-04; Updated: 2026-07-07; Datestamp: 2026-07-07
We aim to identify the physical mechanism responsible for the observed X-ray emission and POLARIZATION of Cyg X-1 in the soft state. We performed a detailed spectral analysis of X-ray data obtained with NICER, NUSTAR, and INTEGRAL during observations simultaneous with IXPE on 2023 June 20, supplemented at higher energies with archival CGRO data. We developed a new model, retBB, which describes thermal disk emission and its returning reflection, and applied it together with accurate models of Comptonization and RELATIVISTICally broadened reflection. Using the resulting spectral solution, we computed the expected POLARIZATION signal and compared it with the IXPE measurements. Our spectropolarimetric modeling shows that the observed POLARIZATION is in agreement with being produced by Comptonization in a corona undergoing a semi-RELATIVISTIC outflow at a velocity of ~0.3c. Our spectral solutions admit either low or high black-hole spin values, depending on the adopted model setup. However, the observed POLARIZATION strongly favors a low spin. At high spin, the POLARIZATION angle would inevitably rotate significantly across the energy band, which is inconsistent with the observations. Apart from this rotation of the POLARIZATION angle, general RELATIVISTIC effects do not play a significant role in producing the observed POLARIZATION. In particular, we find that, at most, returning disk radiation contributes only a minor amount.
[abstract 8 / 92] Wow! (score: 7) - Title: Non-thermal emission in JETs and winds: Expected emission and spectral index distributionsAuthors: M. Meenakshi, D. Mukherjee, G. Bodo, P. Rossi, C. M. Harrison, L. K. Morabito, P. Kharb, S. Silpa,Comments: Submitted to MNRAS. 23 pages, 13 figuresSubjects: astro-ph.HECreated: 2026-07-02; Updated: 2026-07-07; Datestamp: 2026-07-07
The origin of SYNCHROTRON emission in compact radio sources associated with ACTIVE GALACTIC NUCLEi (AGN) remains poorly understood. In a series of papers, we have examined diagnostic tools to disentangle the dominant underlying processes. In this study, we investigate the in situ evolution of cosmic-ray electrons (CREs) in compact AGN JETs and winds, and examine how their evolution shapes the resulting observable radio properties. In JETs, CREs experience multiple shock interactions as they propagate along the spine toward the hotspot and flow into the cocoon via backflows. In winds, CREs are predominantly accelerated at the Mach disc, with occasional re-acceleration within turbulent cocoon backflows. The continuous mixing of different CRE populations within the cocoon produces observational signatures that cannot be inferred from instantaneous conditions alone. In all JET simulations, spectral indices are flattest near the hotspot and steepen progressively away from the hotspots. In winds, spectra steepen with increasing distance from the Mach disc, with this trend becoming more pronounced at high radio frequencies due to radiative losses. We find the Mach disc to be a significantly more efficient CRE acceleration site than the forward shock in winds, which weakens as the wind expands to large scales. Since morphology, especially at low resolution, can be ambiguous for compact sources, spatially resolved spectral indices, particularly when combined with emission and POLARIZATION signatures, can provide a powerful diagnostic.
[abstract 9 / 92] Wow! (score: 7) - Title: Helical radio JETs as probes of MAGNETised cluster environments: Periodic Faraday Rotation Revealed in the Corkscrew Galaxy by POSSUMAuthors: Sarah N. Bradbury, C. S. Anderson, N. M. McClure-Griffiths, Y. K. Ma, A. J. M. Thomson, L. Rudnick, S. P. O'Sullivan, B. M. Gaensler, B. S. Koribalski, E. L. Alexander, Takuya Akahori, L. Baidoo, E. Carretti, G. Heald, H. Sakemi, T. Vernstrom, J. West,Comments: 17 pages, 6 figures, accepted for publication in MNRASSubjects: astro-ph.GA astro-ph.HECreated: 2026-07-02; Updated: 2026-07-07; Datestamp: 2026-07-07
Jets from ACTIVE GALACTIC NUCLEi (AGN) that exhibit regular plane-of-sky oscillations may provide a probe of MAGNETised plasma within the JETs and their local intracluster medium (ICM). If such morphologies trace three-dimensional helices, path length differences between near and far sides of the flow might imprint quasi-periodic signatures in Faraday rotation. We present ASKAP Band 2 (1296-1440 MHz) polarimetric observations of a helical-tailed RADIO GALAXy (the "Corkscrew Galaxy") from early science data from the POlarisation Sky Survey of the Universe's Magnetism (POSSUM), and test whether its quasi-periodic morphology produces signatures in Faraday rotation. We detect significant RM oscillations with a spatial period of (342 +/- 101) arcsec, consistent within the Rayleigh resolution limit with the JET's lateral deviations ((290 +/- 72) arcsec). Cross-correlation analysis reveals systematic variation along the JET: the eastern section shows alignment between JET deviation and RM, consistent with a JET-associated or sheath-like Faraday screen, while the western section exhibits a phase shift, indicating a transition in the dominant Faraday-rotating medium and possible contribution from the local ICM. These results demonstrate that quasi-periodic RM signatures can disentangle the dominant Faraday-rotating medium in AGN JETs, and show that in some embedded RADIO GALAXies the dominant RM contribution arises near the source rather than the cluster foreground. We also outline reliability criteria required to avoid false positive detections and inadequate sampling. Helical JET structures therefore show strong promise as probes of MAGNETised cluster environments, a capability that will expand in the SKA era.
[abstract 10 / 92] Wow! (score: 7) - Title: Numerical Simulations of Restarted Jets -- I. DynamicsAuthors: Prathamesh Ratnaparkhi, Dipanjan Mukherjee, Gianluigi Bodo, Paola Rossi, Marisa Brienza, Raffaella Morganti,Comments: submitted to MNRASSubjects: astro-ph.HECreated: 2026-07-03; Updated: 2026-07-07; Datestamp: 2026-07-07
We performed high-resolution three-dimensional RELATIVISTIC MAGNETohydrodynamic (RMHD) simulations of restarted JETs evolving within the cavity of a previous JET episode, using the PLUTO code. The simulations cover a spatial domain of $50\;\mbox{kpc}$ with a resolution of $40\;\mbox{pc}$. Three suites of simulations were performed to understand the impact of JET power, MAGNETic fields and quiescence time on the evolution of restarted JETs. The restarted JETs undergo a complex, multi-stage evolution, with the remnant cocoon relaxing from an initially conical structure to a mushroom-shaped morphology via an intermediate cylindrical phase. As the cocoon of the initial JET expands, dense material entrained by fluid instabilities such as Kelvin-Helmholtz and Rayleigh-Taylor significantly alter the conditions within it. As a result, the interaction of the restarted JET with the cocoon is markedly different from that of the initial JET with the ambient medium. In particular, we find that the restarted JET propagates ballistically through the rarefied remnant cocoon, without creating prominent backflows. Deceleration of the JET and associated backflows are observed only when it encounters dense structures. The structure and strength of the shocks in restarted JETs are affected by JET power, MAGNETic field strength, and quiescence time. Finally, we discuss the implications of the dynamics for observed properties of RADIO GALAXies.
[abstract 11 / 92] Wow! (score: 7) - Title: Beyond the Impulsive Approximation: The Dynamics and Radio Emission of Tidal Disruption JetsAuthors: Fabio De Colle, Enrico Ramirez-Ruiz,Comments: 11 pages, 11 figures. Submitted to ApJL. Comments welcomeSubjects: astro-ph.HECreated: 2026-07-03; Updated: 2026-07-07; Datestamp: 2026-07-07
Radio emission from RELATIVISTIC tidal disruption events (TDEs) is commonly interpreted using the Blandford--McKee solution for an impulsive RELATIVISTIC blast wave. Unlike GAMMA-RAY BURSTs, however, TDE JETs are powered by fallback accretion, injecting energy over weeks to months. We investigate how this sustained energy injection modifies the dynamics and radio emission of RELATIVISTIC TDE JETs using one- and two-dimensional RELATIVISTIC hydrodynamic simulations coupled with SYNCHROTRON radiation calculations. For a fixed total energy, fallback-powered JETs drive slower forward shocks, producing delayed and systematically fainter radio emission. We show that the impulsive approximation is valid only when the duration of energy injection is less than approximately ten percent of the deceleration time of an equivalent Blandford--McKee blast wave, a condition that is generally not satisfied for RELATIVISTIC TDEs. As a result, continuously powered outflows are significantly less beamed than impulsive explosions, leading to a strong suppression of off-axis radio emission. These results demonstrate that the radio evolution of RELATIVISTIC TDEs retains memory of the central engine and cannot, in general, be described by an impulsive solution. By substantially reducing the expected off-axis radio emission, sustained fallback-powered JETs imply that RELATIVISTIC JET production in tidal disruption events may be considerably more common than current radio observations suggest.
[abstract 12 / 92] Yes (score: 6) - Title: Young Massive Star Clusters as TeV Emitters: Constraints from H.E.S.S. and LHAASOAuthors: Rowan Batzofin, Pierre Cristofari, Kathrin Egberts,Comments: Published in A&A 07 May 2026Subjects: astro-ph.HECreated: 2026-07-03; Updated: 2026-07-07; Datestamp: 2026-07-07
Young massive star clusters (YMSCs) have been proposed as excellent candidates for the main sources of Galactic COSMIC RAYs (CRs) up to the PeV range. The detection and study of gamma rays in the very-high-energy (E>100GeV) range has brought arguments in favour of this hypothesis. Current instruments have detected only a few YMSCs. Future observatories are expected to increase this number, providing a larger sample improving our ability to constrain the role of YMSCs in the origin of CRs. We study the population of TeV YMSCs detected and their properties, confronting simulations of the YMSC population to the observed sample, to address the fundamental questions concerning the spectrum of accelerated particles, the efficiency of CR production, and the fraction of the wind luminosity converted into turbulent MAGNETic fields. Using Monte Carlo methods, we simulate the Galactic population of YMSCs in the gamma-ray domain and confront our simulations to the catalogue of sources of the systematic survey of the Galactic plane performed by H.E.S.S. (HGPS) and the First LHAASO Catalogue of Gamma-Ray Sources. We systematically explore the parameter space of our model, including the slope of accelerated particles $α$, the CR efficiency $η_{\rm CR}$, the fraction of the wind luminosity converted into turbulent MAGNETic field $η_{\rm b}$, and the diffusion regime. We found 5 possible sets of parameters for which >75% of realisations agree with the combined data from the HGPS and LHAASO 1st catalogue. Certain regions of the parameter space are strongly disfavoured, such as Bohm diffusion. Our model successfully reproduces the YMSC population observed in both catalogues. With future systematic surveys, e.g. the Cherenkov Telescope Array Observatory (CTAO), this approach will help break degeneracies and improve our understanding of particle acceleration at YMSC shocks in the Galaxy.
[abstract 13 / 92] Yes (score: 6) - Title: Multiwavelength properties of short gamma ray bursts with extended emission observed by SWIFTAuthors: M. M. Dinatolo, A. Mei, R. Brivio, M. Ferro, M. G. Bernardini, P. D'Avanzo, S. Belova, S. Campana, S. Covino, D. Frederiks, B. Haskell, R. Salvaterra, B. Sbarufatti, A. Tsvetkova,Comments: Submitted to A&A. Comments are welcomeSubjects: astro-ph.HECreated: 2026-07-03; Updated: 2026-07-07; Datestamp: 2026-07-07
Short GAMMA-RAY BURSTs with extended emission (SGRBEEs) are a particular class of long GRBs (LGRBs) which, despite their duration, share several observational features with short GRBs (SGRBs). They are composed by a short, hard initial pulse (IP) followed by a longer and softer extended emission (EE). We investigate whether SGRBEEs originate from the same progenitor as SGRBs despite their duration, representing a peculiar subclass of LGRBs, or if they constitute a distinct population. Given their respective duration, we tested if the IP and the EE share properties with short and long GRBs, respectively. We analysed SGRBEEs from the flux-limited, redshift-complete SBAT4 sample using prompt-emission data from SWIFT/BAT, FERMI/GBM and Konus-WIND, and X-ray afterglow observations from SWIFT/XRT. The temporal and spectral properties of the IP and EE components were compared with those of SGRBs from the extended SBAT4 sample and LGRBs from the BAT6 sample. Despite observing a clear spectral evolution during the prompt phase of each SGRBEE, IPs and EEs as well as short and long GRBs can not be distinguished by their hardness ratio only. All bursts analysed have a spectral lag consistent with zero. SGRBEEs XRT light curves are consistently more complex than those of SGRBs, requiring the addition of multiple breaks and showing the presence of steep decays and plateaus. Our results indicate that SGRBEEs are not an intermediate class. During prompt emission, despite common spectral features, IPs and EEs temporally differ from short and long GRBs, respectively. EEs are on average too faint to appear in the Amati plane, but IPs occupy the same parameter space of SGRBs. In the afterglow, SGRBEEs are more luminous than standard GRBs at early-time, suggesting a direct contribution from the EE; at later times, these events behave as standard SGRBs, and both remain systematically less luminous than LGRBs.
[abstract 14 / 92] Yes (score: 6) - Title: Measurements of MAGNETic fields in circumnuclear matter with the SKA telescopesAuthors: Satoko Sawada-Satoh, Yuki Kudoh,Comments: Published in Advancing Astrophysics with the SKA II (AASKAII), 2026 (arXiv:2606.20366). Report-no: AASKAII/Sawada-Satoh01. Advancing Astrophysics with the SKA II (AASKAII) outlines the transformative scientific advances that will be enabled by the SKA telescopesSubjects: astro-ph.GACreated: 2026-07-05; Updated: 2026-07-07; Datestamp: 2026-07-07
Magnetic fields are thought to regulate the angular momentum transfer in ACTIVE GALACTIC NUCLEi (AGNs), yet their strength and structure in circumnuclear regions remain poorly constrained across spatial scales and gas phases. We present a unified observational framework for probing circumnuclear MAGNETic fields using complementary diagnostics: direct measurements via the Zeeman effect in HI absorption and megamaser emission, and indirect constraints from broadband Faraday rotation of polarized continuum radiation. These approaches provide access to MAGNETized gas spanning spatial scales from ~100 parsec (pc) circumnuclear disks down to sub-pc regions near supermassive BLACK HOLEs (SMBHs). The Square Kilometre Array (SKA) telescopes are expected to revolutionize such investigations through their outstanding sensitivities, wide frequency ranges and high spatial resolutions achievable via very long baseline interferometry (VLBI). These capabilities will enable the detection and detailed characterization of weakly polarized emission from MAGNETized circumnuclear matter, which has remained largely inaccessible with current instruments. In this chapter, we review previous measurements of MAGNETic fields in galactic nuclei and discuss the breakthroughs that SKA observations are expected to provide in elucidating the physical conditions and processes shaping AGN environments.
[abstract 15 / 92] Yes (score: 6) - Title: Radio Activity Across Accretion State Changes in Changing-look AGNs: Insights from FIRST and VLASS over Two DecadesAuthors: Zhi-Qiang Chen, Wei-Jian Guo, Victoria A. Fawcett, Jun-Jie Jin, Wen-Ke Ren, Heng-Xiao Guo, Min-Feng Gu, Yan-Mei Chen, Lu Feng, Hu Zou, Qi-Rong Yuan,Comments: Accepted for publication in ApJSubjects: astro-ph.GACreated: 2026-07-05; Updated: 2026-07-07; Datestamp: 2026-07-07
Changing-look ACTIVE GALACTIC NUCLEi (CL-AGNs) provide a unique opportunity to probe the coupling between accretion flows and RELATIVISTIC JETs in supermassive BLACK HOLEs. We investigate the long-term radio behavior of CL-AGNs over approximately 20 years by combining FIRST and VLASS observations with quasi-simultaneous optical spectroscopy and photometry. From a parent sample of 1092 CL-AGNs, we identify 58 sources with radio detections. Radio-detected CL-AGNs exhibit systematically higher radio kinetic efficiency, quantified by \(P_{\rm j}/L_{\rm bol}\), than both typical radio-detected AGNs and radio transients, consistent with their preference for low Eddington ratios. At the population level, the expected anti-correlation between radio emission and accretion rate is weak. However, a clear source-by-source anti-correlation emerges in a small subset of CL-AGNs with continuous multi-epoch coverage. We further identify four radio transients, including both radio turn-on and turn-off events, and one source exhibiting a multiwavelength flare that may be indicative of tidal disruption event-like activity. These results suggest that radio activity in CL-AGNs is not governed by instantaneous accretion state changes but is instead regulated by long-term accretion history and JET evolution, with additional stochastic or transient channels contributing in rare cases.
[abstract 16 / 92] Yes (score: 5) - Title: Complex Analysis of Askaryan Radiation: UHECR ReconstructionAuthors: J. C. Hanson, D. Ibanez-Rodriguez,Comments:Subjects: astro-ph.HECreated: 2026-07-03; Updated: 2026-07-07; Datestamp: 2026-07-07
Ultra-high energy COSMIC RAYs (UHECR) can produce RELATIVISTIC cascades that emit radio-frequency (RF) pulses in the 0.1-1 GHz bandwidth via two distinct effects: the geoMAGNETic effect, and the Askaryan effect. The geoMAGNETic effect occurs when the MAGNETic field of the Earth causes cascade charges to form a transverse current that radiates linearly polarized radiation aligned with the Lorentz force direction. The Askaryan effect is caused by the net negative charge excess in the cascade that radiates linearly polarized radiation along the Cherenkov cone. When UHECR cascades enter solid, RF transparent matter at altitudes where the cascade develops, Askaryan radiation created in the solid medium can propagate to RF detectors. The Askaryan Radio Array (ARA) at the South Pole has observed 13 UHECR candidates in precisely this fashion. We present an analytical model that confirms the events are UHECRs. The model includes Askaryan radiation created within the ice sheet and the ARA RF channel response. The coherently summed waveforms (CSWs) from the UHECR candidates match our model with correlation coefficients between 0.69 and 0.86, and with minimal fractional power differences. Finally, we demonstrate how to obtain the Askaryan E-field from our model, and that it matches the results from the ARA collaboration.
[abstract 17 / 92] Yes (score: 5) - Title: Kinematic detection of dusty outflows from ACTIVE GALACTIC NUCLEi: Polycyclic aromatic hydrocarbon kinematics of type 2 QUASARs with JWST/MIRI spectroscopyAuthors: Fergus R. Donnan, Cristina Ramos Almeida, Omaira González Martín, Karin Sandstrom, Anelise Audibert, Marina Bianchin, Miguel Pereira-Santaella, Ismael García-Bernete,Comments: Accepted for publication in A&A. 13 pages, 12 figuresSubjects: astro-ph.GA astro-ph.HECreated: 2026-07-03; Updated: 2026-07-07; Datestamp: 2026-07-07
Active galactic nuclei (AGN) are thought to have dusty outflows, but unlike in the gas phase, it is challenging to measure the kinematics of dust. We present the detection and analysis of the kinematics of dust in five type 2 QUASARs at $z\sim0.1$ from the Quasar Feedback (QSOFEED) sample observed with JWST/MIRI spectroscopy. We used principal component analysis tomography to produce velocity maps of polycyclic aromatic hydrocarbon (PAH) features, which are the smallest carbonaceous dust particles. We were then able to compare velocity maps of the PAHs with emission lines of ionised and molecular gas. We produced velocity maps of the 11.3 $μ$m PAH feature, which traces large and neutral PAHs, for three out of the five objects, where all three show an outflow in the PAH kinematics. This becomes particularly clear after we subtracted disk kinematics, where the H$_2$ rotational transitions also show residuals consistent with an outflow. Compared to previous work with Seyfert galaxies, this work suggests that dusty outflows are more common at higher Eddington ratios, $λ_{\rm Edd}\gtrsim0.1$, in agreement with previous suggestions, although the sample size is small. We were unable to produce velocity maps for the 6.2 $μ$m PAH, which traces ionised PAHs, potentially due to differences in the intrinsic profile and/or suppression of the feature in AGN, which was seen previously in Seyfert galaxies. This reflects studies of PAH band ratios where AGN outflows have more neutral PAHs. This work demonstrates that dusty outflows may be common, particularly at high Eddington ratios, and it therefore plays a key role in the evolution and life cycle of AGN.
[abstract 18 / 92] Yes (score: 5) - Title: Time Domain Studies of Active Galactic Nuclei with the SKA telescopesAuthors: Hayley Bignall, Rajan Chhetri,Comments: 13 pages. Published in Advancing Astrophysics with the SKA II (AASKAII), 2026 (arXiv:2606.20366). Report-no:AASKAII/Bignall01. Advancing Astrophysics with the SKA II (AASKAII) outlines the transformative scientific advances that will be enabled by the SKA telescopesSubjects: astro-ph.GACreated: 2026-07-03; Updated: 2026-07-07; Datestamp: 2026-07-07
Time domain studies of ACTIVE GALACTIC NUCLEi (AGN) at radio wavelengths probe physical processes near the central engine via intrinsic variability, in particular within the RELATIVISTIC JETs, as well as small-scale structures in the local Galactic interstellar medium (ISM) via scintillation and scattering effects. Recent discoveries reinforce the expectation that the high sensitivity, large field-of-view, and broadband frequency coverage of the SKA telescopes will help to revolutionise our understanding of AGN populations and the evolution of JETs, and allow detailed modelling of the structure and dynamics of scattering plasma in the local ISM over a large fraction of the sky.
[abstract 19 / 92] Yes (score: 5) - Title: The giant radio source 0917+75: Origin and propertiesAuthors: G. Giovannini, N. Biava, M. Girardi, W. Boschin, R. Barrena, A. Bonafede, L. Feretti, C. Ferrari, F. Govoni, M. Iacobelli, M. Murgia, E. Orru', R. Pizzo, V. Vacca,Comments: 12 pages, 13 figures, accepted for publication in A&ASubjects: astro-ph.COCreated: 2026-07-03; Updated: 2026-07-07; Datestamp: 2026-07-07
Context. Several author have studied the giant radio source GRS0917 + 75 , but its origin remains unclear. Aims. This source is unusual, because of its large size and its location outside a rich cluster of galaxies. We aim to understand and discuss the properties and nature of this source and its connection to the environment. Methods. We conducted optical observations to obtain new spectroscopic data. We also acquired a LOFAR image at 144 MHz to derive information at low radio frequency. Moreover, we performed a new analysis of archival VLA data in the L and C bands for a multifrequency study of the source properties in the radio band. Results. From the observational data, we classify GRS0917 + 75 as a giant RADIO GALAXy with a size of 1.5 Mpc and an estimated age of about 100 Myr. The optical parent galaxy is a bright low-excitation RADIO GALAXy, the brightest member of a very poor group belonging to a large supercluster. GRS0917 + 75 is a peculiar low-power Fanaroff-Riley Class I giant RADIO GALAXy with a bright central emission but no JET-like features. Conclusions. The existence of giant RADIO GALAXies such as GRS0917 + 75 could explain the origin of RELATIVISTIC particles and MAGNETic fields in low-density environments.
[abstract 20 / 92] Yes (score: 5) - Title: A population of LIGO-Virgo-KAGRA mergers happening inside ACTIVE GALACTIC NUCLEiAuthors: Dhruv Kumar, Alejandro Torres-Orjuela,Comments: 6 pages, 2 figuresSubjects: astro-ph.GA gr-qcCreated: 2026-07-04; Updated: 2026-07-07; Datestamp: 2026-07-07
Multimessenger observations of compact binary mergers in ACTIVE GALACTIC NUCLEi (AGN) offer unique probes of BLACK HOLE formation channels and cosmology. We analyse 18 gravitational-wave events from LVK observing runs O3--O4b paired with 28 candidate AGN counterparts, incorporating supermassive BLACK HOLE (SMBH)-induced environmental redshift corrections and electroMAGNETic sky-localisation constraints. Of the 28 candidate pairs, 21 are positive-to-strong-favoured (the most compelling being GW190412\_053044 $\leftrightarrow$ J143041.67$+$355703.8 at $\ln\mathcal{B} = +17.35$), three are inconclusive, and four are negative-to-strong-disfavoured. From the 21 positive-to-strong-favoured binary BLACK HOLE (BBH) AGN pairs, 13 unique associations can be identified as the preferred ones. The cumulative Bayes factor across all 13 BBH-AGN confirmed associations yields $\ln\mathcal{B}_{\rm comb} \approx +81$, establishing strong collective support for AGN-hosted merger associations. Sky localisation is the dominant driver of model selection; at current detector sensitivity, the environmental redshift corrections are neither decisively confirmed nor ruled out, motivating future high-precision multimessenger follow-up.
[abstract 21 / 92] Yes (score: 5) - Title: Exploring the Influence of the Jet-environment Interactions on the Observed Asymmetry of Extragalactic Radio Sources with SKAOAuthors: Sabyasachi Pal, Souvik Manik, Shobha Kumari, Chiranjib Konar,Comments: Published in Advancing Astrophysics with the SKA II (AASKAII), 2026 (arXiv:2606.20366). Report-no:AASKAII/SabyasachiPal03Subjects: astro-ph.GACreated: 2026-07-04; Updated: 2026-07-07; Datestamp: 2026-07-07
Several observational and theoretical studies have suggested that the observed arm-length asymmetries in extragalactic radio sources are primarily driven by interactions between radio JETs and an inhomogeneous ambient medium, although orientation effects may also contribute to the observed asymmetry. However, the observational evidence supporting these interpretations comes from only a small sample of FR II radio sources, in which the brighter hotspots are typically found on the side of the shorter JET arm. We aim to investigate the interactions between powerful JETs and their surrounding environments in radio sources, with a particular focus on how these interactions shape the morphology and asymmetry of the radio lobes. The unprecedented sensitivity and angular resolution of the Square Kilometre Array Observatory (SKAO) will facilitate the discovery and detailed characterization of asymmetric radio sources across a wide range of physical scales and redshifts. Using a combination of 3D MAGNETohydrodynamic simulations and observational data from the SKAO, one can explore the influence of clumpy interstellar and intergalactic media on JET propagation and the resulting asymmetries in radio sources at various redshifts. The study will analyze how environmental factors, such as density and turbulence, decelerate JETs, leading to observable asymmetries in smaller, higher-redshift sources. In this chapter, we review existing simulation and observational results on JET-environment interactions in RADIO GALAXies and discuss how SKAO capabilities will further advance our understanding of AGN feedback and its role in shaping large-scale cosmic structure.
[abstract 22 / 92] Yes (score: 4) - Title: FEADME: Fast Elliptical Accretion Disk Modeling EngineAuthors: Nicholas Earl, K. Decker French, Jason T. Hinkle, Yashasvi Moon, Margaret Shepherd, Margaret E. Verrico, Samaresh Mondal, Ferdinand,Comments: 21 pages, 7 figures, submitted to ApJSubjects: astro-ph.HECreated: 2026-07-03; Updated: 2026-07-07; Datestamp: 2026-07-07
We present FEADME (Fast Elliptical Accretion Disk Modeling Engine), a GPU-accelerated Python framework for modeling broad Balmer-line emission using a RELATIVISTIC elliptical accretion-disk formalism. Leveraging JAX and NumPyro for differentiable forward modeling and efficient Bayesian inference, FEADME enables large-sample, reproducible analyses of disk-dominated emission-line profiles. We apply the framework to 237 double-peaked emitters (DPEs) from the literature and to five tidal disruption events (TDEs) with disk-like H$α$ emission, fitting three physically motivated model families per spectrum and selecting the preferred model using the widely applicable information criterion (WAIC). After posterior-quality filtering, the disk-bearing ACTIVE GALACTIC NUCLEi (AGN) analysis sample contains 165 sources and the TDE sample contains 27 usable epochs. We find that AGN occupy a broad, continuous distribution of disk geometries and kinematics that is usefully summarized by five phenomenological Gaussian-mixture morphology bins. The TDE disk parameters overlap substantially with the AGN population in radial scale, local broadening, and emissivity slope, but TDEs are systematically less eccentric and show broader non-disk Gaussian components. The majority of both AGN and TDEs favor models that include both a disk and an additional broad-line component, suggesting that disk emission commonly coexists with more isotropic or wind-driven gas. These results indicate that once a line-emitting disk forms, its spectroscopic appearance is governed by similar physical processes in both persistent AGN and transient TDE accretion flows, and they demonstrate the utility of FEADME for population-level studies of disk structure in galactic nuclei.
[abstract 23 / 92] Yes (score: 4) - Title: Cygnus X-3 as a PeVatron and the LHAASO 2025 dataAuthors: M. Kachelriess, E. Lammert,Comments: v2: 4 pages, added possibility of increased absorption in line-driven WR wind; v3: added discussion, version published in OJASubjects: astro-ph.HECreated: 2026-07-04; Updated: 2026-07-07; Datestamp: 2026-07-07
We have recently argued that the high-mass X-ray binary Cygnus X-3 can accelerate COSMIC RAYs (CR) beyond PeV energies. Meanwhile, the LHAASO collaboration published the measurement of an orbitally modulated photon flux from Cygnus X-3 extending up to 4 PeV. In this short extension of our previous work, we argue that these observations point towards CR acceleration in the JET, and secondary production in CRs scattering on gas from the wind and on stellar UV photons from the companion star. The latter channel leads naturally to a contribution to the photon flux peaking around PeV energies which is strongly orbitally modulated. The fast drop in the flux of these photons below PeV energies may be caused by absorption on an increased density of background photons in a line-driven stellar wind.
[abstract 24 / 92] Yes (score: 4) - Title: Evolution and Impact of Switchbacks Throughout the HeliosphereAuthors: Alfred Mallet, Chen Shi, Anna Tenerani, Oleksiy Agapitov, Mojtaba Akhavan-Tafti, Samuel Badman, Nina Bizien, Trevor Bowen, Mihir I. Desai, J. F. Drake, Timothy Horbury, Andrea Larosa, Maria S. Madjarska, Francesco Malara, Lorenzo Matteini, Mathew Owens, Victor Réville, Nikos Sioulas, Shirsh Lata Soni, Jonathan Squire, Gabriel Ho Hin Suen, Marc Swisdak, Marco Velli, Jaye Verniero, Nicholas Watkins, Luca Sorriso-Valvo,Comments: 60 pages, 21 figures, submitted to Space Science ReviewsSubjects: physics.space-ph astro-ph.SR physics.plasm-phCreated: 2026-07-02; Updated: 2026-07-07; Datestamp: 2026-07-07
Magnetic switchbacks are large-amplitude fluctuations in the interplanetary MAGNETic field, and appear frequently in the near-Sun solar wind explored recently by Parker Solar Probe: these new observations have prompted many new studies into their properties and origins. Here, we first review what is known about how switchbacks evolve as they travel away from the Sun: both in terms of their expansion-driven growth and their decay due to various processes like turbulence, RECONNECTion, dispersion, parametric instability, and interaction with interplanetary shocks. We then review the current state of knowledge on how switchbacks impact the physics of the solar wind as a whole: in terms of the turbulent cascade, acceleration and heating of the wind, modification of the open solar flux and scattering of energetic particles. Finally, we suggest future studies to further our understanding of switchback evolution and impacts on the heliosphere.
[abstract 25 / 92] Yes (score: 4) - Title: Jet--ISM Interactions in Gaseous Disks: Simulating Kinetic Feedback in the Radio Galaxy 3C 326 NAuthors: Mayur B. Shende, Dipanjan Mukherjee, N. P. H. Nesvadba, Geoffrey Bicknell, James Leftley, Moun Meenakshi, Raghav Gogia,Comments: 21 pages, 21 figures, submitted to MNRASSubjects: astro-ph.GACreated: 2026-07-03; Updated: 2026-07-07; Datestamp: 2026-07-07
Several RADIO GALAXies, such as 3C\,326\,N, show signatures of JET--ISM coupling, but a complete theoretical framework for explaining them is still lacking. Interpreting these observations requires a detailed understanding of the gas distribution, geometry, and outflow energetics. In this paper, we use three-dimensional RELATIVISTIC hydrodynamic simulations to investigate JET--ISM coupling in inhomogeneous gaseous disks, exploring a parameter space spanning different cloud configurations, JET powers, and central disk densities. Our simulations incorporate a numerical turbulence injection scheme that maintains vertical support in the disk, preventing the unphysical collapse encountered in previous studies. We find that JET--ISM coupling is strongly governed by the underlying cloud configuration, leading to distinct outflow morphologies, velocity dispersions, and kinetic energies. Simulations with small-scale ($l_{\rm c,max}=50$~pc) clouds produce the highest velocity dispersions and kinetic energies, whereas large-scale cloud configurations ($l_{\rm c,max}=250$~pc) yield the lowest values, with mixed cloud distributions exhibiting intermediate behavior. In addition, mixed cloud configurations give rise to asymmetric JET propagation, naturally producing unequal lobe lengths similar to those observed in RADIO GALAXies. We compare our fiducial simulation (a $10^{45}\,\rm erg\,s^{-1}$ JET interacting with a mixed cloud configuration) with observations of 3C\,326\,N, focusing on the morphology of the JET-driven bubble, synthetic emission and the gas kinematics. Our results successfully reproduce the observed properties, providing strong evidence that JET--ISM interactions can account for the wide bubble and the complex gas kinematics observed in this system.
[abstract 26 / 92] Yes (score: 4) - Title: Galactic Centre Pulsars with the SKAOAuthors: F. Abbate, A. Carleo, S. Chatterjee, J. Cordes, P. B. Demorest, G. Desvignes, R. P. Eatough, E. Hackmann, Z. Hu, M. Kramer, J. Lazio, K. J. Lee, K. Liu, I. Rammala-Zitha, S. M. Ransom, G. Saowanit, L. Shao, P. Torne, R. Wharton, J. Wongphechauxsorn, W. Zhu,Comments: Published in Advancing Astrophysics with the SKA II (AASKAII), 2026 (arXiv:2606.20366). Report-no:AASKAII/Abbate01. Advancing Astrophysics with the SKA II (AASKAII) outlines the transformative scientific advances that will be enabled by the SKA telescopes. An earlier version was published in The Open Journal of Astrophysics with arXiv ID: arXiv:2512.16155Subjects: astro-ph.HECreated: 2026-07-03; Updated: 2026-07-07; Datestamp: 2026-07-07
The detection of a pulsar closely orbiting our Galaxy's supermassive BLACK HOLE - Sagittarius~A* - is one of the ultimate prizes in pulsar astrophysics. The RELATIVISTIC effects expected in such a system could far exceed those currently observable in compact binaries such as double neutron stars and pulsar white dwarfs. In addition, pulsars offer the opportunity to study the MAGNETo-ionic properties of Earth's nearest galactic nucleus in unprecedented detail. For these reasons, and more, a multitude of pulsar searches of the Galactic Centre have been undertaken, with the outcome of just seven pulsar detections within a projected distance of 100\,pc from Sagittarius~A*. It is currently understood that a larger underlying population likely exists, but it is not until observations with the SKA have started that this population can be revealed. In this chapter, we look at important updates since the publication of the last SKAO science book and offer a focused view of observing strategies and likely outcomes with the updated SKAO design.
[abstract 27 / 92] Yes (score: 4) - Title: Physically motivated AGN emissivity profiles and their effects on QUASAR microlensing signatures. 1. Multi-epoch accretion disc size inferenceAuthors: Scott Hagen, Carina Fian,Comments: 12 pages, 5 figures, 3 appendices. Submitted to A&A, comments welcomeSubjects: astro-ph.GA astro-ph.HECreated: 2026-07-03; Updated: 2026-07-07; Datestamp: 2026-07-07
Quasar microlensing is uniquely sensitive to the size-scale of the accretion flow, offering one of the few direct probes of the accretion structure on micro-arcsecond scales. However, microlensing-based measurements in the optical and UV often find sizes systematically larger than expected from standard Shakura-Sunyaev disc theory, commonly referred to as the disc-size problem similar to that seen in continuum reverberation campaigns. But this assumes that all the emission comes from a single compact disc, neglecting the diffuse emission from the BLR which originates on much larger spatial scales. In this paper we directly quantify the effect of large-scale diffuse emission on the observed microlensing signatures. We adapt the physically motivated agnsed model to construct energetically self-consistent emissivity profiles in any given bandpass. Since this also predicts the full SED, we combine these SEDs with cloudy to give a diffuse BLR component. We convolve these models with representative microlensing magnification maps, and generate mock microlensing light curves to directly assess the inferred source size under different physical conditions. While the detailed shape of the disc emissivity profile has only a higher-order effect on the microlensing profile, the inclusion of the BLR makes a significant impact since this naturally smooths out the caustic network over larger scales. This introduces a significant bias when interpreted purely as a compact disc. However, the strength of this bias depends predominantly on the fractional contribution of the diffuse emission to the SED in the bandpass being considered, as this sets the effective half-light radius, giving an important wavelength dependence. We conclude that part of the excess in microlensing-inferred accretion disc sizes could arise from interpreting a composite (disc+BLR) picture as a single compact disc.
[abstract 28 / 92] Yes (score: 4) - Title: PKS 2155-304: Long-Term Optical Photometric Monitoring and Variability AnalysisAuthors: J. L. Weiss, I. Andruchow, E. J. Marchesini, S. Cellone, L. Zibecchi, J. P. Varela, L. Mammana, E. Jofré, R. Petrucci,Comments:Subjects: astro-ph.GACreated: 2026-07-03; Updated: 2026-07-07; Datestamp: 2026-07-07
Through the detailed study of the optical flux behaviour in BLAZARs over time, it is possible to infer the conditions responsible for their observed emission. PKS 2155-304, a BL Lac object detected from radio to TeV energies, is among the brightest BLAZARs in the southern hemisphere. We present optical monitoring spanning over two decades using telescopes at Complejo Astronómico El Leoncito and Estación Astrofísica de Bosque Alegre, Argentina. Differential light curves in the B, V, R, and I bands reveal significant variability on weekly and longer timescales, with occasional changes on sub-four-hour scales. The optical spectral index remained negative, consistent with non-thermal emission, and hardened over the past nine years. Evidence for quasiperiodic behaviour on 20-30 day timescales was found, while correlations with X-ray fluxes were weak, suggesting distinct emission components in the two bands. These results highlight the pronounced optical variability of PKS 2155-304 and provide insight into its multi-band emission mechanisms
[abstract 29 / 92] Yes (score: 4) - Title: Tracing the Origin of Circular-Symmetry Diffuse Radio Sources in the Next-Generation SKAO EraAuthors: Sabyasachi Pal, Shobha Kumari, Souvik Manik, Marek Jamrozy, Ananda Hota,Comments: Published in Advancing Astrophysics with the SKA II (AASKAII), 2026 (arXiv:2606.20366). Report-no:AASKAII/SabyasachiPal02Subjects: astro-ph.GACreated: 2026-07-04; Updated: 2026-07-07; Datestamp: 2026-07-07
Circularly symmetric diffuse radio sources represent a recently recognized and rare class of extragalactic SYNCHROTRON-emitting structures whose physical origin remains uncertain. The currently known population is small, and the limited frequency coverage, sensitivity, and polarimetric information available from existing observations hinder robust discrimination among the various proposed formation scenarios. This chapter presents an overview of four representative circular diffuse sources featuring diverse morphologies, such as a horseshoe-shaped inner ring, circular diffuse emission surrounded by inner S/Z-shaped structures and a double-ring diffuse source. The angular sizes of these sources are in the range of 60-100 arcsec, similar to odd radio circles (ORCs). These systems illustrate the morphological diversity of circular diffuse radio emission and provide valuable clues to the physical processes responsible for their formation. The Square Kilometre Array Observatory (SKAO), with its unprecedented sensitivity, wide instantaneous bandwidth, sub-arcsecond imaging capability, and high-fidelity polarimetric performance, will significantly advance the study of these objects. SKAO surveys are expected to detect a substantially larger population of faint circular diffuse radio sources, enabling the first statistically meaningful studies of their occurrence, environments, and evolution. An expanded sample will allow investigations of their cosmological evolution and help determine whether their origin is linked to AGN feedback processes, episodic JET activity, galaxy interactions, or large-scale structure formation. This chapter summarizes the current observational knowledge of circular diffuse radio sources and describes how next-generation radio facilities, particularly the SKAO, will enable progress in understanding the origin and physical nature of these enigmatic radio structures.
[abstract 30 / 92] Yes (score: 4) - Title: Long-period radio transient PSR J0901-4046 is not an Isolated White Dwarf PulsarAuthors: Maxim Lyutikov, Mukremin Kilic, Alexander Wolszczan, Craig Heinke,Comments:Subjects: astro-ph.HECreated: 2026-07-04; Updated: 2026-07-07; Datestamp: 2026-07-07
We report the {\it Chandra} non-detection of PSR J0901$-$4046, a $P=75.89 $ seconds long-period radio transient (LPT). For a distance of 467 pc, the upper limit on X-ray luminosity is $L_X \leq$ few $\times 10^{28}$ erg s$^{-1}$. For the measured $P$ and $\dot{P}$, this upper limit, approximately 50 times lower than the previous {\it SWIFT} observations, is comparable to the spin-down luminosity of a neutron star, but would be approximately four orders of magnitude smaller than the spindown power of a white dwarf. Our results disfavor isolated WDs as the central star in PSR J0901$-$4046. We suggest that the isolated LPTs are powered by MAGNETic dissipation (not rotation), in a way similar to MAGNETars' radio emission.
[abstract 31 / 92] Yes (score: 4) - Title: Particle dynamics in nonlinear electroMAGNETic waves: chaos onset, diffusive heating, and wave surfingAuthors: Maxim Lyutikov,Comments:Subjects: physics.plasm-ph astro-ph.HECreated: 2026-07-05; Updated: 2026-07-07; Datestamp: 2026-07-07
We investigate the dynamics of charged particles interacting with ultra-intense electroMAGNETic X-modes in strongly MAGNETized plasmas. We demonstrate that particle motion becomes chaotic for relative wave intensities $δ= B_w/B_0 \gtrsim 0.25$ (not above the field reversal threshold $δ\geq 1$). The transition to chaos occurs via the Chirikov resonance overlap mechanism and the related destruction of Kolmogorov-Arnold-Moser (KAM) tori. The maximum Lyapunov exponent increases logarithmically with $δ$, even though the unMAGNETized $δ\to \infty$ limit is strictly integrable. In the $δ\gg 1$ regime, incomplete re-laminarization of the phase space flow leads to two distinct populations: (i) the majority of particles undergoing stochastic diffusion, and (ii) a fraction of particles that become phase-locked with the wave, experiencing macroscopic intermittent surfing (Lévy flights). The 1D Particle-In-Cell simulations using the EPOCH code in the highly MAGNETized ($σ\gg 1$) and under-dense regime are generally consistent with the Hamiltonian single-particle theory. The dissipation fraction of the initial EM energy remains mild.
[abstract 32 / 92] (score: 3) - Title: Numerical Studies on the Radio Afterglows in TDE: Bow ShockAuthors: Guobin Mou, Xinwen Shu,Comments: 12 pages. Its companion work focuses on two-fluid simulations of the forward shock model (arXiv:2510.14715)Subjects: astro-ph.HE astro-ph.GACreated: 2026-07-05; Updated: 2026-07-07; Datestamp: 2026-07-07
The origin of radio afterglows or delayed radio flares in tidal disruption events (TDEs) is not fully understood. They could be generated either by a forward shock propagating into diffuse circumnuclear medium (CNM), or a bow shock around a dense cloud, each of which is fundamentally different. To elucidate the distinctions between these two scenarios, we conducted two-fluid simulations incorporating RELATIVISTIC electrons to investigate the spatial evolution of these electrons after being accelerated by shock. Based on their spatial distribution, we performed radiative transfer calculations to obtain the SYNCHROTRON spectra. In Paper I (Mou 2025), we reported the results for the forward shock scenario; in this article, we focus on the bow shock scenario. Compared to that from the forward shock whose peak frequency typically lies around GHz and decreases with time, the radio emission from the bow shock peaks at higher frequencies, typically $\sim$1-20 GHz, and its flux rises more steeply than $t^4$ across our explored parameter space. The radio flux from the bow shock also responds to fluctuations in the outflow. The combined effects of the bow shock and forward shock substantially alter radio spectra, causing significant deviations from the single-zone emission model, and in some cases producing multi-component feature in spectra. This study highlights the importance of the bow shock, and inspires a novel approach for probing dense gas on sub-parsec scales in galactic nuclei by decomposing the bow shock radio spectrum to reveal the conditions of circumnuclear dense gas.
[abstract 33 / 92] (score: 3) - Title: Search For a Counterpart to the Subsolar Mass Gravitational Wave Candidate S251112cmAuthors: Nicholas Vieira, Noah Franz, Bhagya Subrayan, Charles D. Kilpatrick, David J. Sand, Wen-fai Fong, Griffin Hosseinzadeh, Kate D. Alexander, K. Azalee Bostroem, Jillian Rastinejad, Kerry Paterson, Manisha Shrestha, Phillip Noel, P. Darc, Jeniveve Pearson, Aysha Aamer, A. Souza Santos, Luidhy Santana-Silva, Clecio R. Bom, Regis Cartier, Hemanth Bommireddy, Ósmar Rodríguez, Jennifer E. Andrews, Conor Ransome, Vasileios Paschalidis, Jay Strader, Aldana Grichener, J. Quirola-Vásquez, Sergiy Vasylyev, Marcelle Soares-Santos, Collin T. Christy, Brian Hsu, D. Carson Fuls, Yize Dong, Daniel E. Reichart, Jonathan Pineda-García, Kathryne J. Daniel, Daryl Janzen, C. E. Fields, Ann Zabludoff, Nicolas Meza, Felipe Olivares E., Kristine Spekkens, Benjamin Weiner, Maia Williams, Alex R. Gibbs, Frank Shelly, Aravind P. Ravi, Saurabh W. Jha, Stefano Valenti, Joshua Haislip, David E. Trilling,Comments: 20 pages, 8 figures in body; accepted to ApJSubjects: astro-ph.HECreated: 2026-07-02; Updated: 2026-07-07; Datestamp: 2026-07-07
The recent candidate gravitational-wave (GW) alert from a compact object merger involving at least one subsolar mass (SSM) object has prompted questions about their origins. S251112cm is reported by LIGO/Virgo with a false alarm rate of 1 per 6.2 years, nearby luminosity distance $93 \pm 27$ Mpc, and probability of containing a SSM object of 100%. Such a system, if astrophysical, likely did not involve the supersolar neutron stars or BLACK HOLEs invoked to explain kilonovae. One must then also invoke hitherto unobserved and speculative models to produce SSM mergers which may have electroMAGNETic (EM) counterparts. We introduce a framework which vets and scores candidate counterparts to SSM GW events to inform follow-up in search of any among the zoo of potential EM transients: kilonovae, kilonovae-within-SUPERNOVAe, super-kilonovae, or AGN flares from binary BLACK HOLE mergers. We use a suite of telescopes to perform tiling, galaxy-targeted observations, and photometric/spectroscopic follow-up of promising candidates. In near-real time, we ingest candidates reported by the community, including some of the first observations reported by the Vera C. Rubin Observatory. We vet and score a total of 456 candidates, including 67 from Rubin, but find no likely counterpart. We nonetheless highlight candidates which demonstrate the ability of our framework to distinguish between different transient types and describe strategies to maximize the chances of detecting a counterpart to the next SSM event. Our framework will be implemented in the forthcoming Multimessenger Tool for Rapid Object Vetting and Examination (TROVE).
[abstract 34 / 92] (score: 3) - Title: Transient narrowband radio bursts from the MAGNETar 1E 1547.0-5408Authors: Marcus E. Lower, Paul Scholz, Fernando Camilo, David M. Palmer, John E. Reynolds, John M. Sarkissian, Lawrence J. Toomey, George Younes,Comments: Submitted. Comments welcomeSubjects: astro-ph.HECreated: 2026-07-05; Updated: 2026-07-07; Datestamp: 2026-07-07
Radio-loud MAGNETars are well known for exhibiting radiative behaviors that are seldom seen among the wider pulsar population. Yet one form of emission that remains elusive among pulsars and MAGNETars is narrowband bursts of radio waves. Such emission is a hallmark of repeating sources of fast radio bursts (FRBs), intense radio flashes that originate from distant galaxies. Here, we report the detection of 84 narrowband radio bursts during observations of the MAGNETar 1E 1547.0-5408 by the Murriyang telescope. They were confined to a transient profile component that appeared between 2009 February 23 to 25, one month after its 2009 outburst. Their appearance coincided with both dramatic changes in the MAGNETar line-of-sight MAGNETic-field geometry, and an emergent pulsed hard X-ray component detected by the Rossi X-ray Timing Explorer. The leading edge of the hard X-ray emission was phase-aligned with the narrowband component. This may indicate the bursts originated from pair cascades along closed field lines, though open-field line emission remains valid. Our characterization of the bursts suggests they may represent a low-energy analogue of the repeating FRB mechanism, further linking FRB progenitors to young, highly MAGNETized neutron stars.
[abstract 35 / 92] (score: 3) - Title: Probing heartbeat oscillations from the BLACK HOLE X-ray binary GRS 1915+105 using spectral-timing analysisAuthors: Karan Akbari, Chintan Patel, Sayantan Bhattacharya, Sudip Bhattacharyya, Manojendu Choudhury,Comments: 28 pages, 3 tables, 8 figures, accepted for publication in ApJSubjects: astro-ph.HECreated: 2026-07-03; Updated: 2026-07-07; Datestamp: 2026-07-07
GRS 1915+105 is a BLACK HOLE X-ray binary whose $ρ$-class ("heartbeat") oscillations ($\sim$50--100 s) are attributed to radiation-pressure instabilities in the inner accretion disk at near-Eddington luminosities. We present a phase-resolved spectral and timing analysis of 24 SWIFT XRT observations (1--10 keV) and broadband AstroSat SXT+LAXPC data (0.8--30 keV), dividing each cycle into five phases. The narrow-band XRT fits show an apparent anti-correlation between the inner disk temperature ($T_{\rm in} \sim 1.7$--$1.5$ keV) and apparent radius ($R_{\rm in} \sim 22$--$38$ km) across the cycle. The broadband AstroSat fits, however, are statistically consistent with a constant disk temperature: a joint fit with $T_{\rm in}$ tied across all five phases gives $T_{\rm in} = 1.275 \pm 0.020$ keV ($χ^2_ν= 1.003$; $Δχ^2 = +4.3$ for 4 added constraints), whereas tying the disk normalization as well is rejected ($Δχ^2 = +175.9$), leaving a $\sim$20% variation in apparent $R_{\rm in}$ ($18.1 \pm 0.7$ to $21.9 \pm 0.7$ km). The coronal electron temperature rises from $\sim$6 to $\sim$14.5 keV approaching the burst, with the photon index tracking it. We attribute the larger XRT disk swings to its limited bandpass, where coronal Comptonization is unconstrained and the disk parameters absorb coronal variability; the dominant variability is therefore coronal, consistent with Vadawale et al. (2001), and the residual $R_{\rm in}$ change is plausibly a color-correction effect (Zoghbi et al. 2016). Hardness--intensity and color--color diagrams show clear spectral hysteresis. Our broadband coverage provides a phase-resolved test of disk constancy and favors coronal evolution as the driver of the spectral variability across the $ρ$ cycle.
[abstract 36 / 92] (score: 3) - Title: The Information Content of Quasar Variability Light Curves: How Well Can we Infer Stochastic Model Parameters?Authors: Brendon J. Brewer, Geraint F. Lewis, Xiang Yu, Yuan Li,Comments: Published in the Open Journal of Astrophysics. 18 pages, 7 figures, 3 tablesSubjects: astro-ph.GA physics.data-an stat.APCreated: 2026-07-03; Updated: 2026-07-07; Datestamp: 2026-07-07
Quasar variability, driven by multi-scale physical processing within a RELATIVISTIC accretion disk, is commonly modelled with stochastic time series models. The simplest of these is the Damped Random Walk (DRW), also known as the Ornstein-Uhlenbeck (OU) process. Here, we demonstrate that, when fitting such a model to QUASAR light curve data, the mean of the light curve, $μ$, should not be fixed (which is the typical approach), as this leads to overconfident inferences about the variability timescale $τ$, with substantially underestimated uncertainties. However, the short term volatility parameter $η$ is typically very well constrained from short light curves. Through simulations, we compute information theoretic quantities such as the conditional entropy and the mutual information, confirming that light curves provide much more information about $η$ than about $τ$. As a result, we recommend that future QUASAR variability studies focus on $η$ rather than $τ$. To demonstrate this approach, we fit a hierarchical Bayesian regression model for $η$ as a function of bolometric luminosity and rest wavelength to a dataset of 570 light curves measured over decades. We perform the fit using a likelihood function that uses the light curves directly, rather than using intermediate $η$ values from individual light curve fits. We find that volatility decreases as a function of both bolometric luminosity and rest wavelength. The volatility also decreases more steeply with redshift than time dilation alone would suggest, pointing to an increase in intrinsic volatility as QUASARs evolve over cosmic time.
[abstract 37 / 92] (score: 3) - Title: The youth of the intracluster medium. I. A non-parametric characterisation of the gas and electron number density profiles of $z \simeq 2$ protoclustersAuthors: David Vallés-Pérez, Annalisa Bonafede, Klaus Dolag, Marco Balboni, Paolo Tozzi, Marika Lepore,Comments: 13 pages, 8 figures (+ 7 pages, 8 figures in the Appendices). Resubmitted to A&A after revisionsSubjects: astro-ph.CO astro-ph.GA astro-ph.HECreated: 2026-07-02; Updated: 2026-07-07; Datestamp: 2026-07-07
Context. Protoclusters of galaxies are the earliest phase in the assembly of galaxy clusters and can provide invaluable information about plasma physics, cosmic MAGNETism, and cosmology. However, due to small angular sizes and cosmological dimming, observing the proto-intracluster medium (proto-ICM) associated with protocluster cores is far from trivial. Aims. We aim to provide a non-parametric description of the gas mass and electron number density profiles of the proto-ICM at $z = 2$, and to study their dependence on mass, dynamical state and central activity. Methods. We extract and analyse over $3800$ regions around protocluster cores with spherical-overdensity masses above $M_\mathrm{500c} > 10^{13} \, M_\odot$ out of a large simulated volume within the Magneticum suite. We study their density profiles, temperature structure, ionisation degree and electron number density as a function of mass and other secondary properties characterising dynamical state and central activity, extending from the central halo to the surrounding protocluster environment. Results. Protoclusters present moderate deviations from self-similarity in their density profiles and temperature structure, with a strong double-$β$ structure especially relevant at high masses and intense AGN accretion. Hot, ionised gas is only dominant at intermediate radii ($r \gtrsim [0.1-0.5] R_\mathrm{500c}$), where its density also correlates with mass and dynamical disturbance. Conclusions. These results constitute the basis for a forthcoming parametric calibration of proto-ICM density profiles, which could be useful for interpreting observables sensitive to the density and ionisation of the diffuse gas.
[abstract 38 / 92] (score: 3) - Title: The MIRI Early Obscured-AGN Wide Survey (MEOW): A Population of Hidden AGN at $z \gtrsim 5$ Revealed by JWST/MIRI ImagingAuthors: Gene C. K. Leung, Anna-Christina Eilers, Ryan Endsley, Steven L. Finkelstein, Micaela B. Bagley, Guillermo Barro, Anton M. Koekemoer, Pablo G. Pérez-González, Nor Pirzkal, Bren E. Backhaus, Teodora-Elena Bulichi, Jaclyn B. Champagne, Katherine Chworowsky, Nikko J. Cleri, Mark Dickinson, Xiaohui Fan, Seiji Fujimoto, Norman A. Grogin, Allison Kirkpatrick, Dale D. Kocevski, Vasily Kokorev, Rebecca L. Larson, Ray A. Lucas, Fabio Pacucci, Casey Papovich, Anthony J. Taylor, Natalia C. Villanueva, Guang Yang,Comments: 22 pages, 13 figures. Submitted to ApJSubjects: astro-ph.GACreated: 2026-07-02; Updated: 2026-07-07; Datestamp: 2026-07-07
We present the MIRI Early Obscured-AGN Wide Survey (MEOW), a JWST/MIRI imaging survey designed to detect dust-obscured ACTIVE GALACTIC NUCLEi (AGN) across cosmic time, with a particular focus on the high-redshift universe at $z \gtrsim 5$. MEOW observes the GOODS-N and GOODS-S fields with 43 pointings covering 95 arcmin$^2$ with the F1000W and F2100W filters, reaching depths of 0.5 and 3.6 $μ$Jy ($5σ$), respectively. Using spectral energy distribution (SED) modeling combining MEOW photometry with archival HST, JWST/NIRCam, and SCUBA-2 data, we identify a sample of 16 MIRI-selected AGN at $z = 4.5$--$7.2$ (12 spectroscopically confirmed), spanning bolometric luminosities of $L_{\rm bol} = 10^{44.6}$--$10^{46.4}$~erg~s$^{-1}$. Twelve of the 16 AGN are newly identified in this work, including at least five narrow-line AGN representing the obscured population to which broad-line spectroscopic searches are insensitive. Two broad-line AGN exhibit markedly different mid-infrared emission properties, consistent with one being a little red dot (LRD) and the other either a typical AGN or an LRD with unusually strong hot-dust emission. The MIRI-selected AGN bolometric luminosity function at $z = 4.5$--$6$ yields number densities comparable to those of broad-line AGN and LRDs, suggesting that obscured AGN contribute significantly to the total AGN census at these epochs. The narrow-line AGN reside in diverse host environments, with evidence for both circumnuclear and host-galaxy-scale obscuration, pointing to multiple physical mechanisms at work. These results establish JWST/MIRI imaging as an indispensable component of a multi-faceted approach to a complete census of early supermassive BLACK HOLE growth.
[abstract 39 / 92] (score: 3) - Title: Satellite quenching by radio JETs of central galaxies in galaxy groupsAuthors: Yijun Wang, Tao Wang, Dingyi Zhao, Yingjie Peng, Ziwen Zhang, Houjun Mo, Feng Yuan, Zhaozhou Li, Lingyu Wang, Yu Qiu, Yangyao Chen, Ke Xu,Comments: 10 pages, 3 figures (7 supplementary figures), submittedSubjects: astro-ph.GACreated: 2026-07-02; Updated: 2026-07-07; Datestamp: 2026-07-07
Feedback from ACTIVE GALACTIC NUCLEi (AGN) is now recognized as a key component of galaxy formation models. It plays a central role in regulating the growth and quenching of galaxies in the center of groups. However, the impact of AGN feedback from central galaxies on satellite galaxies remains largely unexplored. Here based on the largest sample to date of radio AGNs in galaxy groups (Yang et al. 2007) and a comprehensive consideration of multiple physical parameters that may influence the STAR FORMATION of satellite galaxies, we demonstrate that the quiescent satellite fraction around radio AGNs is higher than that around normal galaxies. The most significant enhancement is observed around AGNs with large radio lobes. These findings demonstrate that the impact of kinetic AGN feedback beyond their host galaxies to their satellites. These results provide novel insights into the physical origins of some long-standing puzzles in extragalactic astronomy, including, e.g., galactic conformity and the strong small-scale clustering of quiescent galaxies.
[abstract 40 / 92] (score: 3) - Title: Evading the CMB $μ$-distortion bound on Supermassive Primordial Black Hole seeds with Non-Gaussian tailsAuthors: Sanket Dave, Sheng-Feng Yan, Amara Ilyas, Yi-Fu Cai,Comments: 14 pages, 6 figuresSubjects: astro-ph.CO gr-qc hep-ph hep-thCreated: 2026-07-03; Updated: 2026-07-07; Datestamp: 2026-07-07
Supermassive BLACK HOLEs (SMBHs) powering QUASARs at $z \gtrsim 6$ are difficult to grow from stellar mass remnants, motivating seeds from primordial BLACK HOLEs (PBHs) with masses $10^5-10^7 M_{\odot}$. This range is constrained by the COBE/FIRAS bound on the CMB $μ$-distortion, which limits the small-scale curvature variance to $σ_ζ^2 \lesssim 10^{-4}$. For Gaussian perturbations, the variance fixes the far tail of the one-point probability distribution function (PDF), making the PBH abundance negligible. We call this the Gaussian barrier. The barrier can be evaded only if the variance probed by the distortion is decoupled from the tail probability controlling collapse. We implement this idea in the non-perturbative $δN$ formalism and relate asymptotic PDF tails to the global shape of the $δN$ map. Four Gaussian-cored families are analyzed: generalized-normal, stretched-exponential, power-law, and log-normal tails. After standardizing each family to unit variance, we impose the FIRAS cap and compute the distortion-limited PBH abundance in the tail-shape parameter space. The ordinary exponential tail produced by standard single-field non-attractor dynamics is still too light to reopen the seed window. Algebraic tails from fractional-potential dynamics, and sufficiently heavy log-normal tails treated as a phenomenological proxy for multiplicative dynamics, can supply seed-relevant abundances while respecting the distortion bound.
[abstract 41 / 92] (score: 3) - Title: Euclid: A UV-faint QUASAR in a highly luminous star-forming host galaxy at $z \approx 7.7$Authors: S. Belladitta, R. Decarli, E. Bañados, F. Walter, D. Yang, F. Guarneri, K. Jahnke, S. Bisogni, S. E. I. Bosman, X. Fan, Y. Fu, J. F. Hennawi, Y. Matsuoka, D. J. Mortlock, M. Onoue, J. -T. Schindler, L. Spinoglio, D. Stern, F. Wang, G. Vietri, C. J. Willott, J. Wolf, J. Yang, R. A. A. Bowler, K. I. Caputi, D. L. Clements, C. M. Gutierrez, H. J. A. Rottgering, D. Scott, F. Shankar, G. Zamorani, A. -C. Eilers, B. Altieri, S. Andreon, N. Auricchio, C. Baccigalupi, M. Baldi, A. Balestra, S. Bardelli, P. Battaglia, A. Biviano, M. Brescia, S. Camera, V. Capobianco, C. Carbone, J. Carretero, S. Casas, M. Castellano, G. Castignani, S. Cavuoti, K. C. Chambers, A. Cimatti, C. Colodro-Conde, G. Congedo, C. J. Conselice, L. Conversi, Y. Copin, A. Costille, F. Courbin, H. M. Courtois, J. -G. Cuby, A. Da Silva, H. Degaudenzi, G. De Lucia, H. Dole, M. Douspis, F. Dubath, X. Dupac, S. Dusini, S. Escoffier, M. Farina, R. Farinelli, F. Faustini, S. Ferriol, F. Finelli, P. Fosalba, S. Fotopoulou, M. Frailis, E. Franceschi, M. Fumana, S. Galeotta, K. George, B. Gillis, C. Giocoli, J. Gracia-Carpio, A. Grazian, F. Grupp, L. Guzzo, S. V. H. Haugan, H. Hoekstra, W. Holmes, I. M. Hook, F. Hormuth, A. Hornstrup, M. Jhabvala, B. Joachimi, S. Kermiche, A. Kiessling, B. Kubik, M. Kümmel, M. Kunz, H. Kurki-Suonio, R. Laureijs, A. M. C. Le Brun, S. Ligori, P. B. Lilje, V. Lindholm, I. Lloro, G. Mainetti, D. Maino, E. Maiorano, O. Mansutti, S. Marcin, O. Marggraf, M. Martinelli, N. Martinet, F. Marulli, R. J. Massey, E. Medinaceli, S. Mei, M. Melchior, M. Meneghetti, E. Merlin, G. Meylan, A. Mora, M. Moresco, L. Moscardini, C. Neissner, R. C. Nichol, S. -M. Niemi, C. Padilla, S. Paltani, F. Pasian, K. Pedersen, W. J. Percival, V. Pettorino, S. Pires, G. Polenta, M. Poncet, L. A. Popa, L. Pozzetti, F. Raison, A. Renzi, J. Rhodes, G. Riccio, H. -W. Rix, E. Romelli, M. Roncarelli, B. Rusholme, R. Saglia, Z. Sakr, D. Sapone, B. Sartoris, M. Schirmer, P. Schneider, T. Schrabback, A. Secroun, G. Seidel, E. Sihvola, P. Simon, C. Sirignano, G. Sirri, L. Stanco, P. Tallada-Crespí, A. N. Taylor, I. Tereno, N. Tessore, S. Toft, R. Toledo-Moreo, F. Torradeflot, I. Tutusaus, L. Valenziano, J. Valiviita, T. Vassallo, Y. Wang, J. Weller, F. M. Zerbi, E. Zucca, J. García-Bellido, J. Martín-Fleitas, P. Monaco, V. Scottez, M. Viel,Comments: 12 pages, 6 figures, 1 table, Accepted for Publication in A&ASubjects: astro-ph.GA astro-ph.COCreated: 2026-07-03; Updated: 2026-07-07; Datestamp: 2026-07-07
Constraining the co-evolution of supermassive BLACK HOLEs and their host galaxies in the first billion years after the Big Bang is essential for understanding the formation of the earliest cosmic structures. Here, we present IRAM/NOrthern Extended Millimeter Array (NOEMA) observations of the $z \approx 7.7$ QUASAR EUCL\,J125308.55+705432.3, recently discovered in the first data release of the Euclid Wide Survey. We report the most distant detections of [CII] 158$μ\mathrm{m}$ and cold dust emission in a QUASAR host to date. The [CII] emission line sets the systemic redshift at $z=7.6980\pm0.0004$. The source exhibits luminosities of $L_{\rm FIR}=3.6\times10^{12}\,L_{\odot}$ and $L_{[CII]}=2\times10^9\,L_{\odot}$, respectively, a dust mass of 1.4$\times 10^{8}\,M_{\odot}$, and a dynamical mass in the range 0.33-1.3$\times10^{10}\,M_{\odot}$. Remarkably, despite being nearly two magnitudes fainter in the rest-frame UV ($M_{1450}=-24.06$) than previously known $z\approx7.5$ QUASARs (
[abstract 42 / 92] (score: 3) - Title: Euclid: Discovery of 31 new QUASARs at $6.6 < z < 7.8$Authors: D. Yang, J. F. Hennawi, F. Guarneri, J. Wolf, S. Belladitta, J. -T. Schindler, A. C. N. Hughes, E. Bañados, D. J. Mortlock, J. Yang, F. Wang, X. Fan, K. Jahnke, D. Stern, C. J. Willott, A. J. Barth, H. J. A. Rottgering, R. G. Varadaraj, R. Decarli, A. -C. Eilers, M. Ezziati, Y. Fu, J. Huang, X. Jin, Y. Kang, L. N. Martinez-Ramirez, Y. Matsuoka, M. Onoue, R. Pello, R. P. Remigio, W. L. Tee, B. Venemans, G. Vietri, B. Wang, L. J. Abbo, H. Atek, S. Bisogni, S. E. I. Bosman, R. A. A. Bowler, C. J. Conselice, F. B. Davies, C. M. Gutierrez, Y. Harikane, K. Rubinur, C. C. Lovell, M. Magliocchetti, J. Matthee, F. Ricci, M. Scialpi, D. Scott, L. Spinoglio, F. Tarsitano, Y. Toba, F. Walter, J. R. Weaver, G. Zamorani, B. Altieri, A. Amara, S. Andreon, H. Aussel, C. Baccigalupi, M. Baldi, A. Balestra, S. Bardelli, P. Battaglia, A. Biviano, E. Branchini, M. Brescia, S. Camera, G. Cañas-Herrera, V. Capobianco, C. Carbone, J. Carretero, M. Castellano, G. Castignani, S. Cavuoti, K. C. Chambers, A. Cimatti, C. Colodro-Conde, G. Congedo, L. Conversi, Y. Copin, F. Courbin, H. M. Courtois, M. Cropper, J. -C. Cuillandre, H. Degaudenzi, G. De Lucia, C. Dolding, H. Dole, M. Douspis, F. Dubath, X. Dupac, S. Dusini, S. Escoffier, M. Farina, R. Farinelli, S. Ferriol, F. Finelli, N. Fourmanoit, M. Frailis, E. Franceschi, M. Fumana, S. Galeotta, K. George, B. Gillis, C. Giocoli, P. Gómez-Alvarez, J. Gracia-Carpio, A. Grazian, F. Grupp, L. Guzzo, S. Gwyn, S. V. H. Haugan, H. Hoekstra, W. Holmes, I. M. Hook, F. Hormuth, A. Hornstrup, M. Jhabvala, S. Kermiche, B. Kubik, K. Kuijken, M. Kümmel, M. Kunz, H. Kurki-Suonio, A. M. C. Le Brun, S. Ligori, P. B. Lilje, V. Lindholm, I. Lloro, G. Mainetti, D. Maino, E. Maiorano, O. Mansutti, O. Marggraf, M. Martinelli, N. Martinet, F. Marulli, R. J. Massey, H. J. McCracken, E. Medinaceli, S. Mei, Y. Mellier, M. Meneghetti, E. Merlin, G. Meylan, J. J. Mohr, A. Mora, M. Moresco, L. Moscardini, E. Munari, R. Nakajima, C. Neissner, R. C. Nichol, S. -M. Niemi, C. Padilla, S. Paltani, F. Pasian, K. Pedersen, W. J. Percival, V. Pettorino, S. Pires, G. Polenta, M. Poncet, L. A. Popa, L. Pozzetti, G. D. Racca, F. Raison, R. Rebolo, A. Renzi, J. Rhodes, G. Riccio, H. -W. Rix, E. Romelli, M. Roncarelli, C. Rosset, B. Rusholme, R. Saglia, Z. Sakr, D. Sapone, M. Sauvage, M. Schirmer, P. Schneider, T. Schrabback, A. Secroun, G. Seidel, S. Serrano, E. Sihvola, P. Simon, C. Sirignano, G. Sirri, L. Stanco, J. Steinwagner, P. Tallada-Crespí, I. Tereno, N. Tessore, S. Toft, R. Toledo-Moreo, F. Torradeflot, I. Tutusaus, L. Valenziano, J. Valiviita, T. Vassallo, Y. Wang, J. Weller, F. M. Zerbi, E. Zucca, G. Fabbian, M. Huertas-Company, J. Martín-Fleitas, P. Monaco, V. Scottez, M. Viel,Comments: Accepted for publication in A&ASubjects: astro-ph.GACreated: 2026-07-03; Updated: 2026-07-07; Datestamp: 2026-07-07
We report the discovery of 31 new high-$z$ QUASARs in the redshift range $6.6 < z < 7.8$. These QUASARs were selected from approximately 3000 deg$^2$ of sky covered during the first 1.5 years of the Euclid Wide Survey, representing the initial results of the Euclid high-$z$ QUASAR search. Our candidate selection employed multiple machine-learning and probabilistic techniques applied to the Euclid $I_E$, $Y_E$, $J_E$, and $H_E$ images, supplemented by ancillary $z$-band data when available. Spectroscopic follow-up observations were carried out with Keck, Magellan, and the Large Binocular Telescope (LBT). Among the new discoveries, there are 12 QUASARs at $z \geq 7$, more than doubling the number of previously known QUASARs at $z \geq 7$. The newly discovered QUASARs exhibit $21.2 < J_E < 23.2$ ($-25.5 < M_{1450} < -23.6$), extending QUASAR studies to the faint end of the QUASAR luminosity function (QLF) at $z \gtrsim 7$. The QUASAR with the highest-$z$, EUCL J172902.75+641018.1 at $z \approx 7.77$, sets the new redshift record for the most distant QUASAR ever reported. These discoveries demonstrate Euclid's transformative role in high-$z$ QUASAR discovery and set the stage for future follow-up studies of the early galaxies hosting QUASARs, supermassive BLACK HOLE growth, and the intergalactic medium in the epoch of reionisation.
[abstract 43 / 92] (score: 3) - Title: Constraining Pulsar Radiative Geometry via Multi-wavelength ModelingAuthors: Tong Zhao, Shunshun Cao, Renxin Xu,Comments:Subjects: astro-ph.HECreated: 2026-07-05; Updated: 2026-07-07; Datestamp: 2026-07-07
We propose that jointly modeling the thermal X-ray pulse profiles and the POLARIZATION position angles offers an effective means of locating the POLARIZATION orientation focus of the pulsar's coherent radiation. From the X-ray pulse-profile measurement we constrain the colatitude of the center of the thermal X-ray emission, which corresponds to the center of in-falling particles within the polar cap, while the RVM fitting yields the inclination angle of the focus point of POLARIZATION orientations. Thus, consistency between these two independent angle measurements would imply that the RVM fit faithfully recovers the inclination of the plasma flow center, and this center coincides with the POLARIZATION orientation focus. Conversely, the discrepancy would suggest that the POLARIZATION state of the radio emission changes as it propagates because the evolution of wave modes during wave propagation in the MAGNETosphere strongly depends on MAGNETic field orientations.
[abstract 44 / 92] (score: 3) - Title: Exploring Hierarchical Merger Scenarios for GW241011 and GW241110Authors: Lei He, Liang-Gui Zhu, Zheng-Yan Liu, Rui Niu, Chao Wei, Ken Chen, Wen Zhao,Comments: 11 pages, 4 figuresSubjects: astro-ph.HECreated: 2026-07-06; Updated: 2026-07-07; Datestamp: 2026-07-07
GW241011 and GW241110 are asymmetric binary BLACK HOLE mergers with rapidly spinning primaries, unequal component masses, and nonzero spin--orbit tilts, making them natural candidates for hierarchical mergers. We use a Bayesian framework to compare a fiducial first-generation (1G+1G) binary BLACK HOLE population with second-generation plus first-generation (2G+1G) hierarchical merger models in star clusters and ACTIVE GALACTIC NUCLEus (AGN) disks. Both events favor the 2G+1G interpretation over the 1G+1G hypothesis, with $\ln\mathcal{B}^{\rm 2G+1G}_{\rm 1G+1G}\simeq6.5$--$8.6$ for GW241011 and $\ln\mathcal{B}^{\rm 2G+1G}_{\rm 1G+1G}\simeq3.0$--$4.5$ for GW241110, depending on the waveform model and assumed environment. The AGN disk models yields slightly larger evidence than the star cluster models, mainly due to their spin tilt distribution, but the data do not provide a decisive environmental classification. We further consider a third-generation plus first-generation (3G+1G) interpretation, but it is not robustly preferred over 2G+1G scenarios. Finally, we also search for optical counterparts by examining AGNs within the three-dimensional localization volumes using ZTF and ATLAS forced photometry, and find one candidate source with weak flare, which might be associated with GW241110 event.
[abstract 45 / 92] (score: 3) - Title: A new model of QUASAR mass evolutionAuthors: Z. Li, M. Zhang, Q. -H. Peng, X. Liu,Comments: Published in ApSS; 8 pages, 5 figuresSubjects: astro-ph.GACreated: 2026-07-06; Updated: 2026-07-07; Datestamp: 2026-07-07
Magnetic monopoles have been a trending topic among physicists and astronomers since the 1930s. Researchers have been working hard to find evidence of MAGNETic monopoles in laboratories. The existence of MAGNETic monopoles can rationally explain the stability of charges, the quantization of charges, the structure of leptons, the unified composition of leptons and hadrons, and the symmetry of leptons and QUARKs. The presence of these mysterious particles in the universe could have significant implications for theoretical physics and astrophysics. The Grand Unified Theory has also predicted the existence of MAGNETic monopoles, which is interestingly implied by some astronomical observations. Noticing that the growth of supermassive BLACK HOLEs in the early universe is an increasingly challenging difficulty faced by astronomers, here we argue that it could be solved with the help of MAGNETic monopoles. As suggested by Peng et al. in A Monopole Model for Galactic Nuclei. In: Structure and Evolution of Active Galactic Nuclei, vol. 121, p. 663 (1986), QUASARs containing MAGNETic monopoles at the center can continuously catalyze the decay of protons to release energy. We examine this model by using QUASAR data from the Sloan digital sky survey. It is shown that the initial mass distribution of QUASARs derived from the MAGNETic monopole model exhibits a Gaussian distribution. At the same time, the initial mass function is also slightly higher than previously expected, which could be verified by future observations.
[abstract 46 / 92] (score: 3) - Title: Deep Learning Models for ADITYA-U MHD EquilibriumAuthors: Udaya Maurya, Suman Aich, Indranil Bandyopadhyay, Daniel Raju,Comments: 18 pages, 42 figures, 15 tablesSubjects: physics.plasm-phCreated: 2026-07-06; Updated: 2026-07-07; Datestamp: 2026-07-07
This work presents deep learning models to predict MAGNETohydrodynamic equilibrium parameters and profiles for the ADITYA-U tokamak. A synthetic free-boundary equilibrium dataset consisting of 100,760 cases was generated using the pyIPREQ Grad-Shafranov solver, with inputs derived from 766 ADITYA-U plasma discharges and constrained to experimentally relevant circular limiter plasmas near the flat-top phase. Several deep learning approaches were investigated for predicting scalar equilibrium quantities, one-dimensional safety factor profiles and two-dimensional poloidal flux profiles. These approaches included Dense neural networks, principal component analysis based reduced-order models, one-dimensional and two-dimensional convolutional neural networks, and physics-informed neural networks incorporating Grad-Shafranov residual constraints. In addition, an inverse model was developed to estimate poloidal field coil currents from desired plasma equilibrium conditions. The results demonstrate that key equilibrium parameters and profiles can be accurately estimated within the operational domain represented by the dataset. The developed models provide a computationally efficient alternative to conventional equilibrium estimation and can be useful for real-time plasma control, rapid equilibrium analysis, and experimental planning in ADITYA-U operations.
[abstract 47 / 92] (score: 2) - Title: FAST Pulsar Database: II. Scattering profiles of 149 PulsarsAuthors: W. C. Jing, J. L. Han, C. Wang, P. F. Wang, T. Wang, N. N. Cai, J. Xu, Z. L. Yang, D. J. Zhou, Yi Yan, W. Q. Su, X. Y. Gao, L. Xie,Comments: The pulsar sample expanded from 122 to 149. This paper will be published in RAASubjects: astro-ph.HE astro-ph.GACreated: 2026-07-03; Updated: 2026-07-07; Datestamp: 2026-07-07
The turbulent ionized interstellar medium diffracts radio waves and makes them propagate in multiple paths. The pulse-broadening observed at low frequencies results from the scattering effect of interstellar clouds of ionized gas. During the Galactic Plane Pulsar Snapshot (GPPS) survey and other projects by using the Five-hundred-meter Aperture Spherical radio Telescope (FAST), we detect the pulse-broadening for 149 pulsars in the radio frequency band between 1.0 and 1.5 GHz, including 68 newly discovered pulsars in the GPPS survey and 81 previously known pulsars. We find that a more accurate dispersion measure can be obtained from aligning the front edge of the scattered subband pulses at the 1/4 or 1/2 peak level for most pulsars with one dominant component in the intrinsic profile, and the best DM values from aligning the intrinsic profile components from the model-fitting. From the pulse profiles at a few subbands we derive the pulse-broadening timescale and the scattering spectral index. These scattering parameters are measured for the first time for 113 pulsars. For 36 pulsars with previously detected scattering features, our measurements of the pulse-broadening timescale are consistent with results in the literature. We find that pulsars behind spiral arms show a stronger scattering effect due to greater density fluctuations in the arm regions. With a properly derived dispersion measure and careful calibration, we also present POLARIZATION profiles for 82 pulsars in three subbands of FAST observations.
[abstract 48 / 92] (score: 2) - Title: Environmental effects in stellar mass gravitational wave sources II: Enhanced detectability of phase shifts in eccentric sub-populationsAuthors: Lorenz Zwick, Kai Hendriks, Pankaj Saini, János Takátsy, Connar Rowan, Johan Samsing, Jakob Stegmann,Comments: Accepted in ApJ, comments welcome!Subjects: astro-ph.HE gr-qcCreated: 2026-07-04; Updated: 2026-07-07; Datestamp: 2026-07-07
We demonstrate that the properties of eccentric gravitational wave (GW) signals enhance the detectability of GW phase shifts caused by environmental effects (EEs): The signal-to-noise ratio (SNR) of EEs can be boosted by up to $\ell_{\rm max}^{1 - n}$ with respect to corresponding circular signals, where $\ell_{\rm max}$ is the highest modeled eccentric GW harmonic and $n$ is the frequency scaling of the GW dephasing prescription associated to the EE. We investigate the impact on a population level, adopting plausible eccentricity distributions for binary sources observed by LIGO/Virgo/Kagra (A+ and A\# sensitivities), as well as Cosmic Explorer (CE) and the Einstein Telescope (ET). For sources in the high eccentricity tail of a distribution ($e \gtrsim 0.2$ at 10 Hz), phase shifts can systematically be up to $\ell_{\rm max}^{1 - n}$ times smaller than in a corresponding circular signal and still be detectable. For typical EEs, such as Roemer delays and gas drag, this effect amounts to SNR enhancements that range from $10^2$ up to $10^5$. For CE and ET, our analysis shows that EEs will be an ubiquitous feature in the eccentric tail of merging binaries, regardless of the specific details of the formation channel. Additionally, we find that the joint analysis of eccentricity and phase shift is already plausible in current catalogs if a fraction of binaries merge in AGN migration traps.
[abstract 49 / 92] (score: 2) - Title: Extending the Numerical Flow Iteration to the multi-species Vlasov-Maxwell system through Hamiltonian SplittingAuthors: Rostislav-Paul Wilhelm, Fabio Bacchini, Sebastian Schöps, Manuel Torrilhon, Melina Merkel, Matthias Kirchhart,Comments:Subjects: physics.plasm-ph cs.NA math.NACreated: 2026-07-03; Updated: 2026-07-07; Datestamp: 2026-07-07
The Numerical Flow Iteration (NuFI) method has recently been proposed as a memory-slim while accurate in phase-space method for the electro-static Vlasov--Poisson system. It stores the temporal evolution of the electric field, instead of the distribution functions, and reconstructs the solution in each time step by following the characteristics backwards in time and reconstructing the solution from the initial distribution. NuFI has been shown to be more accurate than other state-of-the-art electro-static Vlasov solvers given the same amount of degrees of freedom. In this paper, we build on the Hamiltonian structure of the full Vlasov--Maxwell system to extend NuFI to handle electro-MAGNETic kinetic plasma dynamics. We show that the structure-preserving properties of the NuFI time-stepping are preserved when extending to the electro-MAGNETic case. Furthermore we discuss how NuFI can be incorporated into existing Semi-Lagrangian codes as an efficient while accurate subcycling technique.
[abstract 50 / 92] (score: 2) - Title: Images of shadow and thin accretion disk around Bardeen BLACK HOLE surrounded by perfect fluid DARK MATTERAuthors: Haiyuan Feng, Ziqiang Cai, Hao-Peng Yan, Rong-Jia Yang, Jinjun Zhang,Comments: 56 pages, 97 figuresSubjects: astro-ph.HE gr-qcCreated: 2026-07-03; Updated: 2026-07-07; Datestamp: 2026-07-07
We investigate the shadow and optical appearance of Bardeen BLACK HOLE (BH) immersed in perfect fluid DARK MATTER (PFDM). Using EHT observations of M87* and Sgr A*, we constrain the DM parameter to a narrow range $b/M \sim \mathcal{O}(10^{-1}-10^{-2})$ for M87* and to $\mathcal{O}(10^{-2}-10^{-3})$ for Sgr A*. From these constraints we derive a rough prediction for the PFDM density near the shadow scale ($R_{\mathrm{sh}}\sim5M$): $ρ_{\mathrm{PFDM}} \sim 0.27$-$2.67\,\mathrm{g/cm^3}$ for Sgr A*, dropping to $\sim10^{-24}$-$10^{-25}\,\mathrm{g/cm^3}$ at 100 pc. Moreover, increasing $b$ substantially enlarges the photon sphere, impact parameter, shadow radius, and suppresses the observed disk brightness, while the MAGNETic charge $g$ produces only negligible corrections completely masked by PFDM on macroscopic scales. Subsequently, we investigate the primary/secondary images, flux, and redshift profiles for the PFDM-Bardeen BH using the Novikov-Thorne disk model, and compare these quantities with those of NFW, Dehnen-type and Moore DM BHs. The four BH types exhibit distinct densities at the shadow radius and at 100 pc, offering a potential distinguishing signature. Furthermore, for all DM BH models, blueshift appears in the primary image as inclination increases, while the secondary image remains redshift dominated even at high inclinations. Hence, if significant blueshifted emission were detected at low inclination, the predictions of these four DM models would be seriously challenged.
[abstract 51 / 92] (score: 2) - Title: Revealing massive BLACK HOLE astrophysics: The potential of hierarchical inference with extreme mass-ratio inspiral observationsAuthors: Shashwat Singh, Christian E. A. Chapman-Bird, Christopher P. L. Berry, John Veitch,Comments: 19 pages, 6 figures, 3 tablesSubjects: astro-ph.HE gr-qcCreated: 2026-07-03; Updated: 2026-07-07; Datestamp: 2026-07-07
Gravitational waves from extreme mass-ratio inspirals (EMRIs) will enable sub-percent measurements of massive BLACK HOLE parameters and provide access to the demographics of compact objects in galactic nuclei. During the LISA mission, multiple EMRIs are expected to be detected, allowing statistical studies of massive BLACK HOLE populations and their formation pathways. We perform hierarchical Bayesian inference on simulated EMRI catalogues to assess how well LISA could constrain the astrophysical population using parametrised population models. We test our inference framework on a variety of populations, including heterogeneous and homogeneous mixtures of parametrised subpopulations, and scenarios in which the assumed model is deliberately misspecified. Our results show that population parameters governing distributions with sharp features can be tightly constrained. Mixed populations can be disentangled with as few as $\sim20$ detections, and even with model misspecification, the inference retains sensitivity to key population features. These results demonstrate the capabilities and limitations of EMRI population inference, providing guidance for constructing realistic astrophysical population models for LISA analysis.
[abstract 52 / 92] (score: 2) - Title: Galactic Dust Polarization in Turbulent Multiphase ISM: On the Origin of the $EE/BB$ AsymmetryAuthors: Yue Hu, Bao Truong, Thiem Hoang, Le Ngoc Tram,Comments: 21 pages, 11 figures, accepted for publication in ApJSubjects: astro-ph.GACreated: 2026-07-03; Updated: 2026-07-07; Datestamp: 2026-07-07
Polarized thermal emission from Galactic dust is the dominant foreground for CMB POLARIZATION measurements at high frequencies, with its statistical properties shaped by the interplay between turbulence and MAGNETic fields in the multiphase interstellar medium (ISM). Variations in turbulence regime and density-MAGNETic-field alignment across the warm (WNM), unstable (UNM), and cold (CNM) neutral media should imprint distinct signatures on the power spectra and $EE/BB$ power ratio, yet the relative contributions of these phases remain poorly constrained. Using high-resolution 3D MAGNETohydrodynamic simulations of a turbulent multiphase ISM coupled with synthetic dust POLARIZATION maps, we quantify phase-dependent turbulence, anisotropy, and alignment properties. We find that the trans-Alfvénic and transonic WNM and UNM are strongly anisotropic, exhibiting tight alignment of density and velocity structures with the local MAGNETic field. In contrast, the super-Alfvénic and supersonic CNM displays reduced anisotropy and weak alignment. These dynamical differences are reflected in the statistical scaling of fluctuations: the square root of the second-order velocity structure function exhibits a slope near $1/3$ in the WNM, near $1/2$ in the CNM, and intermediate in the UNM. Comparing our synthetic POLARIZATION power spectra with \textit{Planck} measurements, we find that POLARIZATION from UNM dust yields spectral slopes closest to the \textit{Planck}-inferred values, whereas WNM and CNM dust produce steeper and shallower spectra, respectively. The WNM yields $EE/BB>2$, the UNM gives $EE/BB\sim2$, and the CNM yields $EE/BB\approx1$. These results suggest that UNM dust may be an important contributor to the polarized foreground under typical high-latitude ISM conditions. We present predictions at 150 GHz to inform foreground modeling and separation.
[abstract 53 / 92] (score: 2) - Title: Intermediate-Mass Black Hole Formation from Hierarchical Mergers in Galactic NucleiAuthors: Amanda Newton, Sanaea C. Rose, Fulya Kıroğlu, Bao-Minh Hoang, Frederic A. Rasio,Comments: 19 pages, 10 figures; Submitted to ApJSubjects: astro-ph.GACreated: 2026-07-06; Updated: 2026-07-07; Datestamp: 2026-07-07
Dense stellar environments like nuclear star clusters (NSCs) can dynamically assemble gravitational wave (GW) sources. We consider a population of single stellar mass BLACK HOLEs (BHs) in the inner $0.1$~pc of a NSC surrounding a $4 \times 10^6$~M$_\odot$ supermassive BLACK HOLE (SMBH). Using a semianalytic model, we account for direct collisions between BHs and stars and GW capture between BHs. We explore the effect of the initial BH mass and spin distributions on their final properties and the production of GW sources. Specifically, we consider upper and lower limits for the BH initial mass distribution, and we account for the possibility that a subset of our initial population are the merger products of primordial BH binaries. We find that $\sim 500$ M$_{\odot}$ intermediate mass BLACK HOLEs (IMBHs) can form for our upper limit mass distribution, while our lower limit mass distribution forms none. Most IMBHs $\gtrsim 200$~M$_\odot$ eventually sink towards the center of the cluster and merge with the SMBH. We also find successive BH-star collisions can produce low-spinning BHs with $χ\lesssim 0.2$. Our results have implications for LIGO-Virgo-KAGRA sources. We find that the overall merger rate depends primarily on the initial BH mass distribution and is $\gtrsim 10^{-9}$~yr$^{-1}$ per Milky Way-like galaxy for our range of initial conditions. However, primordial binaries can change the number of GW mergers with second and higher generation progenitor BHs by an order of magnitude.
[abstract 54 / 92] (score: 2) - Title: The Outflow of the B335 Protostar II: After the OutburstAuthors: Klaus W. Hodapp, Adwin Boogert, Doug Johnstone, Valentin J. M. Le Gouellec, Eleni Tsiakaliari, Helen J. Fraser, Laurie L. Chu, Thomas Greene, Marcia J. Rieke,Comments: 48 pages, 23 figures. This paper has been accepted for publication in The Astrophysical JournalSubjects: astro-ph.SR astro-ph.GACreated: 2026-07-02; Updated: 2026-07-07; Datestamp: 2026-07-07
The B335 protostar has recently undergone a major, still ongoing, outburst detected in scattered light from its outflow cavity, offering a rare opportunity to study its impact on a protostellar JET. We use JWST/NIRCam photometry of background stars behind B335 from 2.7 to 4.4 $μ$m to map extinction and H$_2$O ice absorption, showing that the outflow has carved a cavity in the molecular core. We measure proper motions of shock fronts emerging from the protostar of 131--227 km s$^{-1}$. The kinematic age of the most prominent shock front, 3E, corresponds to the early phase of the current outburst. JWST/NIRSpec IFU data show that the youngest shock, 2E, exhibits ionic lines but no molecular emission. Shock 3E shows strong CO emission together with H$_2$ and [\ion{Fe}{2}], whereas older shocks show weaker CO and are dominated by H$_2$ and [\ion{Fe}{2}]. The feature 0E, closest to the protostar, appears to be a stationary shock. CO-line-removed spectra near the protostar show that the unsaturated absorption features of $^{13}$CO$_2$, OCN$^-$, and OCS increase strongly toward the source. The ice properties are otherwise similar to those along lower-extinction sight lines. In the central bipolar reflection nebula, CO gas is seen in scattered emission from the immediate protostellar surroundings, but a few arcsec farther out, absorption by cooler CO gas in the outflow cavity is detected.
[abstract 55 / 92] (score: 2) - Title: Breathing Black Hole Shadows in Modified Gravity (MOG)Authors: Nikko John Leo S. Lobos, Emmanuel T. Rodulfo,Comments: 9 Pages, 2 figuresSubjects: gr-qcCreated: 2026-07-04; Updated: 2026-07-07; Datestamp: 2026-07-07
In this paper, we investigate the dynamic phenomenological signatures of a Schwarzschild-MOG BLACK HOLE shadow perturbed by passing gravitational waves. By perturbing the Hamilton-Jacobi equation for photon null geodesics, we demonstrate that the unique field content of MOG breaks the observational degeneracy with standard General Relativity. We mathematically prove two distinct, time-dependent signatures. First, the massless MOG scalar field induces a volumetric ``breathing mode'' POLARIZATION, causing the total apparent area of the shadow to rhythmically expand and contract. Second, the massive MOG vector field undergoes quantum vacuum dispersion, arriving at the observer with a predictable time delay. This delayed massive wave sources secondary longitudinal metric perturbations that manifest as a sudden, asymmetric translational wobble of the shadow on the celestial screen. These dynamic geometric shifts offer a robust observational template for next-generation interferometry to strictly test the existence of massive force carriers and scalar fields in gravity.
[abstract 56 / 92] (score: 2) - Title: Plugging of multi-mirror machines by a traveling rotating MAGNETic fieldAuthors: Tal Miller, Eli Gudinetsky, Ilan Be'ery, Ido Barth,Comments:Subjects: physics.plasm-phCreated: 2026-07-05; Updated: 2026-07-07; Datestamp: 2026-07-07
Axial plugging is a critical challenge for fusion in open-ended MAGNETic confinement systems. Unlike simple MAGNETic mirrors, which suffer from direct axial flow, multi-mirror systems utilize a series of aligned MAGNETic cells to suppress plasma loss; however, the resulting confinement still requires additional plugging to reach Lawson criterion levels. In [T. Miller et al., Phys. Plasmas 30, 072510 (2023)], it was found that applying a traveling and rotating electric field in multi-mirror machines can significantly suppress axial loss due to a selectivity effect induced by the Doppler shift of the ion cyclotron resonance. However, this method is energetically expensive and vulnerable to plasma screening effects. Here, we show that using a traveling, rotating MAGNETic field can achieve comparable plugging effectiveness while offering better penetration and lower energy costs. Two limiting scenarios, with and without an induced electric field, were considered. The confinement enhancement is calculated using a semi-kinetic rate equation model, in which the rate coefficients are determined from single-particle simulations. While both scenarios exhibit significant confinement enhancement, the scenario without an induced electric field is much more energetically efficient, as it relies on phase-space mixing rather than on energy deposition in the escaping particles. The decoupling of confinement from plasma collisionality enables fusion conditions in the central cell while allowing affordable and efficient confinement enhancement in the multi-mirror sections.
[abstract 57 / 92] (score: 2) - Title: The long-term accretion luminosity of V4641 Sgr through binary evolution simulations: implications for its ultrahigh-energy gamma-ray emissionAuthors: Ruo-Yu Liu, Yong Shao, Yu-Dong Nie,Comments: 12 pages, 4 figures; accepted by ApJLSubjects: astro-ph.HECreated: 2026-07-06; Updated: 2026-07-07; Datestamp: 2026-07-07
Recent observations by LHAASO and HAWC have revealed extended ultrahigh-energy (UHE; $E>100$ TeV) gamma-ray emission associated with the black-hole X-ray binary (BHXRB) V4641 Sgr, with a spectrum extending up to $\sim0.8$ PeV. Interpreting this emission requires a very high time-averaged non-thermal particle power, significantly exceeding {the long-term observed X-ray luminosity which is commonly used as a proxy for the accretion power}, leading to an apparent ``energy crisis''. To address this, we perform detailed binary-evolution simulations with \textit{MESA}, constrained by the known system parameters inferred from observation. Across an extensive evolutionary grid, all tracks that match the current system parameters pass through a long-lasting, slow mass-transfer phase, with a time-averaged intrinsic X-ray luminosity of over evolutionary timescales of order $L_X\sim10^{38}$erg/s, far above the observed luminosity average over the last few decades. This is consistent with earlier suggestions of an extended obscuring/reprocessing envelope or outflow in V4641 Sgr. The inferred intrinsic accretion power can then readily supply the energy required to explain the UHE emission under the leptonic model, and is also marginally consistent with the requirement from the hadronic model, resolving the energy crisis. This supports V4641 Sgr as a Galactic PeV particle accelerator.
[abstract 58 / 92] (score: 2) - Title: Real-time virtual circuits for plasma shape control via neural network emulators: dynamic validation in closed-loop simulationsAuthors: K. Pentland, A. Ross, N. C. Amorisco, P. Cavestany, T. Nunn, A. Agnello, G. K. Holt, C. Vincent,Comments:Subjects: physics.plasm-ph physics.comp-phCreated: 2026-07-03; Updated: 2026-07-07; Datestamp: 2026-07-07
Reliable confinement and stable performance of tokamak fusion plasmas require accurate real-time MAGNETic shape control. A promising route to reduced latency and increased flexibility in plasma control systems (PCS) is to emulate physics-based controllers using neural networks. In prior work, we have demonstrated that virtual circuits (VCs), which define the poloidal field coil current vectors able to modify each plasma shape parameter independently, can be accurately emulated with neural network models trained on a large library of simulated Grad-Shafranov equilibria. This enables MAGNETic controllers to accurately adapt to evolving plasma equilibria, in contrast to pre-set VC schedules whose performance degrades upon departure from their reference equilibria. Here, we investigate the performance and robustness of these emulators in closed-loop simulations using the FreeGSNKE Pulse Design Tool (FPDT): a framework that couples the FreeGSNKE evolutive equilibrium solver with a virtual PCS. The FPDT models the coupling between controllers, plasma current and shape response, and actuator constraints. Using the emulated VCs within the FPDT, we demonstrate effective in-silico control of MAST Upgrade (MAST-U) plasma scenarios and show that the emulators are robust in the presence of input measurement uncertainty and under different update frequencies. These results establish the viability of neural network emulated VCs for closed-loop plasma shape control, representing a key step toward real-time deployment in the MAST-U PCS.
[abstract 59 / 92] (score: 2) - Title: Phase-Selective Excitation of Betatron Oscillations by Nonadiabatic Magnetic-Field SwitchingAuthors: R. S. Anandu, B. Ramakrishna,Comments:Subjects: physics.plasm-ph physics.acc-phCreated: 2026-07-03; Updated: 2026-07-07; Datestamp: 2026-07-07
Nonadiabatic removal of an external transverse MAGNETic field provides a phase-selective mechanism for controlling betatron oscillations in LASER wakefield accelerators. When the field is switched off on a timescale shorter than the betatron period, the equilibrium orbit shifts abruptly and acts as an impulsive transverse drive. The induced motion interferes coherently with the preexisting betatron oscillation, leading to phase-dependent enhancement or suppression of the oscillation amplitude. A theoretical model shows that the excitation is governed by the dimensionless switching parameter $χ=ω_βL_s/c$, which distinguishes nonadiabatic and adiabatic regimes. Particle-in-cell simulations confirm the predicted scaling and demonstrate controllable modulation of the betatron radiation spectrum while leaving longitudinal acceleration largely unaffected. These results establish MAGNETic-field switching as a direct mechanism for phase control of RELATIVISTIC betatron oscillations in plasma-based accelerators.
[abstract 60 / 92] (score: 2) - Title: Gyrokinetic equilibria of high temperature superconducting MAGNETic mirrorsAuthors: Maxwell H. Rosen, Manaure Francisquez, James Juno, Ammar Hakim, Gregory W. Hammett,Comments: 8 pages, 4 figuresSubjects: physics.plasm-phCreated: 2026-07-04; Updated: 2026-07-07; Datestamp: 2026-07-07
High-temperature superconducting (HTS) MAGNETs and other advances have led to renewed interest in MAGNETic mirrors for fusion energy. The non-Maxwellian nature of mirror plasmas necessitates kinetic modeling to predict, optimize and design mirrors. Explicit gyrokinetic full-f codes can be used to study instabilities and turbulent transport in tokamaks and mirrors, but they have been prohibitively expensive to integrate directly over the very long time scales required to compute kinetic plasma equilibrium. We demonstrate that these studies are now feasible thanks to novel multiscale methods delivering a 30,000X speed-up. The resulting kinetic equilibrium, electrostatic potential, and ion confinement time are consistent with analytic theory. This transformative capability opens the door to a new way of obtaining equilibria for mirrors, and we discuss how this technique may also accelerate calculations for tokamaks and stellarators. The models presented in this article address critical multiscale problems in modeling MAGNETic mirrors, opening a new research avenue for equilibrium studies using an explicit continuum gyrokinetic code.
[abstract 61 / 92] (score: 2) - Title: Light Propagation Prescriptions for Black Hole MoviesAuthors: Daniel Rojas-Paternina, Alejandro Cárdenas-Avendaño,Comments: 18 pages, 20 figures. V2: Minor changes to match the accepted versionSubjects: astro-ph.HE gr-qcCreated: 2026-07-02; Updated: 2026-07-07; Datestamp: 2026-07-07
The spatiotemporal content of a black-hole movie is set jointly by source variability and by the distribution of light-travel times across the image. In the slow-light prescription, an image evaluated at fixed observer time contains photons emitted at different source times, whereas in fast light all rays sample a single source emission time. In this work we compare these light-propagation prescriptions through the lensing-band structure of Kerr geodesic delays in a controlled semi-analytic setting. For a given emitting geometry, black-hole spin, and observer inclination, we show how the coordinate-time delay distributions of Kerr null geodesics, decomposed by image order across lensing bands, can be compared with the source correlation time to quantify differences between light-propagation prescriptions. We find that when the intrinsic variability timescale is comparable to, or shorter than, the relevant delay spread, the high-inclination mismatch between fast- and slow-light curves can reach several tens of percent. Motivated by this geometric structure, we introduce brisk light, an intermediate prescription that compresses each lensing-band delay map to its dominant temporal interval rather than collapsing the full image to a single source time. The proposed methodology provides both a practical criterion for when slow light matters and an efficient route to black-hole movies that retain the leading temporal imprint of strong lensing, a regime of direct relevance for future space-based VLBI targeting photon-ring observables.
[abstract 62 / 92] (score: 2) - Title: Fast-spinning massive BLACK HOLEs from slowly rotating low-metallicity stars: Implications for GW231123Authors: N. H. Ismail, N. Yusof, R. Hirschi, A. Griffiths, M. Á. Aloy, S. Ekström, G. Meynet,Comments: 6 pages (including 2 appendices) and 2 figures. Accepted for publication in Astronomy & AstrophysicsSubjects: astro-ph.SRCreated: 2026-07-06; Updated: 2026-07-07; Datestamp: 2026-07-07
The origin of massive BLACK HOLEs in the early universe remains uncertain and still unexplored. Pop III stars are among the first stellar sources capable of producing such remnants, but their evolution is very sensitive to rotation. We explore how slow initial rotation influences the evolution and BLACK HOLE formation of very massive Pop III stars, and assess their potential to become massive, fast-spinning BLACK HOLEs consistent with GW events such as GW231123. We compute a grid of non-rotating and slowly rotating Pop III stellar models with initial masses of 80, 85, and 90 $M_\odot$ using the GENEC code. Our models include rotationally induced mixing and angular-momentum transport by MAGNETic torques. We analyse the CO core masses and their volume-averaged adiabatic index to assess stability against electron-positron pair creation. From the angular-momentum profiles at the end of He burning, we estimate the resulting BLACK HOLE masses and dimensionless spins under the assumption of direct collapse. Our non-rotating and slowly rotating 80 and 85 $M_\odot$ models develop carbon-oxygen core masses between 31 and 36 $M_\odot$ and have an adiabatic index that remains above 4/3. Our models thus predict that Pop III stars can keep most of their mass and collapse directly to form BLACK HOLEs of 80 to 85 $M_\odot$ with dimensionless spins up to $a_{\rm BH} \lesssim 0.7$. Initially slowly rotating, massive Pop III stars can form very massive, rapidly spinning BLACK HOLEs just below the pair-instability regime. This supports interpreting the lower boundary of the PISN mass gap as a smooth, structure-dependent transition and identifies single-star Pop III evolution as a possible channel for massive fast-spinning BLACK HOLEs observed by gravitational-wave detectors, subject to the uncertain efficiency of internal angular-momentum transport and mass-loss prescriptions.
[abstract 63 / 92] (score: 2) - Title: Constraints on Binarity for the Extreme Oe Variable Star AzV 493Authors: M. S. Oey, Irene Vargas-Salazar, Edmund Hodges-Kluck, Norberto Castro, Michal K. Szymanski, Mario Mateo, Mathieu Renzo, Mark W. Suffak, Maxwell Moe,Comments: 13 pages, 4 figures, 2 tables. Accepted to PASPSubjects: astro-ph.SR astro-ph.HECreated: 2026-07-03; Updated: 2026-07-07; Datestamp: 2026-07-07
The extreme Oe star AzV 493 is known to show unusual photometric and spectroscopic variability that suggest the presence of an unseen companion in a highly eccentric and long-period (7.3 or 14.6-year) orbit. We obtained a Chandra/ACIS observation near the putative periastron for the 7.3-year orbit to test for transient X-ray emission that would confirm its binary nature. Our data only place an upper limit to the X-ray luminosity of L_X < 2.5 x 10^33 erg/s based on the 0.5 - 8 keV flux limit. Additionally, we obtained 4 new spectroscopic observations with the M2FS spectrograph at Magellan and 20 archive FLAMES/GIRAFFE and X-Shooter spectra from ESO/VLT to further constrain the possibility of radial velocity (RV) variation. Statistical analysis of the RV measurements yields inconclusive results regarding the existence of variations. We discuss possible mass limits for a potential companion, which may be a BLACK HOLE, in the event that the variations are real. The violet-to-red (V/R) Balmer ratio has also recently inverted, which may be a further indication of a companion.
[abstract 64 / 92] (score: 2) - Title: Understanding Non-Gaussian Chorus Wave Statistics via the Benjamin-Feir IndexAuthors: D. J. Ratliff, O. Allanson, D. Rasinskaite, J. Stawarz, C. E. J. Watt, S. Chakraborty, A. W. Smith,Comments: 14 pages, 3 figuresSubjects: physics.plasm-ph math-ph math.MPCreated: 2026-07-03; Updated: 2026-07-07; Datestamp: 2026-07-07
We derive an extended wave action model for equatorial chorus waves, identifying a wave activity index (a version of the Benjamin-Feir index, BFI) which indicates non-Gaussian frequency spectra emerge when BFI$>$0.5. Global maps of this index indicate the night and dawn sectors ($0<{\rm MLT}<9)$ of the MAGNETosphere as the primary region for non-Gaussian wave statistics to emerge. Comparisons with events measured by the Van Allen probe A demonstrate good qualitative agreement whilst identifying key aspects for model refinement. A key strength of our model that our work highlights is its ability to account for the asymmetric frequency spectra characteristic of non-Gaussian chorus. This work ultimately establishes the first wave activity index that distinguishes Gaussian and non-Gaussian wave scenarios from first principles, providing the groundwork for a threshold-based quantification for use in space weather modelling.
[abstract 65 / 92] (score: 2) - Title: Brilliant multi-GeV Compton gamma-ray source seeded by a photon acceleratorAuthors: Michael J. Quin, Stepan S. Bulanov, Arkady Gonoskov, Christopher D. Murphy, Mattias Marklund, Alexander G. R. Thomas, Thomas G. Blackburn,Comments:Subjects: physics.plasm-ph physics.acc-phCreated: 2026-07-03; Updated: 2026-07-07; Datestamp: 2026-07-07
High-brilliance sources of polarized gamma rays are widely sought after to pump and probe matter at subatomic length scales. However, existing accelerator facilities and optical LASERs cannot reach a sufficiently high center-of-mass energy to produce polarized, multi-GeV gamma rays from unpolarized electrons via inverse Compton scattering. Here we propose a scheme where the optical LASER photons are first "accelerated" to the extreme ultraviolet in a beam-driven plasma wakefield, then reflected by a plasma mirror back onto a trailing electron beam, producing a flash of gamma rays. Numerical simulations demonstrate this light source can achieve a high peak-brilliance (10^25 photons/s mm^2 mrad^2 0.1% BW) and a high degree of circular (95 %) or linear (77 %) POLARIZATION at multi-GeV photon energies, paving the way for the production of spin-polarized positrons and tests of light-by-light scattering.
[abstract 66 / 92] (score: 2) - Title: Observational Constraints on Kazakov-Solodukhin Quantum-Deformed Black Holes from M87$^*$ and Sgr A$^*$ ShadowsAuthors: A. Errehymy, Y. Khedif, M. Daoud, B. Turimov, S. Usanov, Z. Yasakov, Z. Avezmuratova,Comments: 14 pages, 9 figures, accepted for publication in Nuclear Physics BSubjects: gr-qcCreated: 2026-07-02; Updated: 2026-07-07; Datestamp: 2026-07-07
We explore the Kazakov-Solodukhin quantum-deformed BLACK HOLE spacetime, characterized by a single deformation parameter \( η\) that encodes quantum corrections to the classical Schwarzschild solution. The model preserves the correct general-RELATIVISTIC limit as \( η\to 0 \), while introducing significant and physically meaningful deviations in the strong-field regime. A central and remarkable feature of the geometry is the regularization of the classical singularity: curvature invariants remain finite near the minimal radius \( r = η\), effectively replacing the divergent core with a smooth and well-behaved region. This behavior naturally introduces a minimal length scale into the spacetime structure, offering a geometrically motivated resolution of the singularity problem. The deformation modifies the horizon structure, shifts the event horizon location, and alters the mass-radius relation. It also reduces the surface gravity, leading to a lower Hawking temperature and a slower evaporation process, thereby enhancing the thermodynamic stability of the BLACK HOLE. Photon dynamics are correspondingly affected, resulting in a displaced photon sphere and modified strong-lensing characteristics. While the shadow remains perfectly circular due to spherical symmetry, its size depends sensitively on \( η\). Observational constraints can be expressed through \( \left| R_{sh}(η) - R_{obs} \right| \leq ΔR_{obs}, \) which places an upper bound on the deformation parameter. In the weak-field limit, the deflection angle acquires a quadratic correction proportional to \( η^2 \), ensuring consistency with precision tests while allowing potentially detectable deviations in strong-gravity observations. These features make the model both theoretically appealing and observationally testable.
[abstract 67 / 92] (score: 2) - Title: RF Helicon Plasma Thruster for an Atmosphere-Breathing Electric Propulsion System (ABEP)Authors: Francesco Romano,Comments:Subjects: physics.plasm-phCreated: 2026-07-02; Updated: 2026-07-07; Datestamp: 2026-07-07
This dissertation focuses on Atmosphere-Breathing Electric Propulsion (ABEP) for propellant-less continuous orbiting in very low Earth orbits (VLEO) and very low Mars orbits (VLMO). ABEP utilizes an intake to collect atmospheric particles as propellant for an electric thruster, offsetting aerodynamic drag. An analytical system-level analysis assesses collectible mass flow, drag, and power requirements, using GOCE as a case study. Three intake designs are developed based on gas-surface interactions. Two diffuse-reflection designs yield collection efficiencies $η_c < 0.5$, while a specular-reflection design achieves $η_c < 0.95$. The specular intake demonstrates superior robustness against flow misalignment, maintaining high efficiency at large angles. The proposed ABEP thruster features a contactless, neutralizer-free design using a helicon plasma discharge, preventing erosion from aggressive species like atomic oxygen. Numerical simulations via the HELIC code determined key design parameters (frequency, MAGNETic field, plasma density), leading to the implementation of a resonant birdcage antenna with high electrical efficiency. The thruster was manufactured and experimentally validated using Ar, N_2, and O_2. Tests demonstrated successful ignition and operation across relevant mass flows with low power consumption ($P_f < 60$ W). Additionally, a B-dot probe was developed to detect helicon waves in the plasma plume. Ultimately, this work delivers verified intake designs and a novel contactless plasma thruster with high electrical efficiency (>99% in vacuum). Both components represent promising technologies for near-future ABEP applications. Future development outlooks, diagnostics, and spacecraft configurations are also discussed.
[abstract 68 / 92] (score: 2) - Title: High-Energy Neutrino Tomography of the Earth's Interior with IceCubeAuthors: The IceCube Collaboration,Comments:Subjects: astro-ph.HE astro-ph.EP hep-ex physics.geo-phCreated: 2026-07-02; Updated: 2026-07-07; Datestamp: 2026-07-07
The Earth's interior reflects its geological evolution, from accretion to present-day dynamics. Its structure drives the geodynamo in the outer core, generating the MAGNETic field that shields the surface from charged cosmic radiation. The primary observables of the Earth's interior are its radial density distribution and derived quantities such as its mass and moment of inertia. These have traditionally been inferred from gravity and seismic wave propagation, which probe the macroscopic response of matter to gravitational and elastic forces. Here we instead constrain the Earth's density profile using high-energy neutrinos observed by the IceCube Neutrino Observatory at the South Pole. We analyze 10.7 years of predominantly muon-neutrino data spanning 500 GeV--100 TeV, including atmospheric neutrinos produced by cosmic-ray interactions in the Earth's atmosphere and the diffuse astrophysical neutrino flux. Neutrino attenuation depends on both the traversed column density and neutrino energy. By measuring the zenith- and energy-dependent flux suppression, we infer the Earth's radial density profile by fitting a concentric uniform-density shell model that incorporates neutrino fluxes, interaction cross sections, detector response, and glacial-ice systematic uncertainties. From the resulting density posteriors, we derive the Earth's mass and polar moment of inertia as measured by neutrinos. These are the most precise weak-interaction measurements of these quantities to date and are consistent with the Preliminary Reference Earth Model and independent gravitational determinations. Our results demonstrate that neutrinos provide a novel probe of planetary interiors via a distinct physical interaction, complementing gravity and seismology. With improved detectors and precision, neutrinos will further contribute to a multifaceted understanding of the Earth's structure.
[abstract 69 / 92] (score: 2) - Title: Limits on global cosmic birefringence using radio sourcesAuthors: Richard A. Battye, Neal Jackson, Ian Browne,Comments: To appear in Physical Review LettersSubjects: astro-ph.CO hep-phCreated: 2026-07-02; Updated: 2026-07-07; Datestamp: 2026-07-07
We have made measurements of the difference between the position angle (PA) on the sky and the POLARIZATION position angle (PPA) of radio sources using data from a combination of the Radio Fundamental Catalogue (RFC) across a range of frequencies between 2.7 and 15~GHz and Cosmic Lens All Sky Survey (CLASS) which observes POLARIZATION at 8.4~GHz (X-band). For the 2111 sources with JET PAs measured in the X-band and a known redshift, the distribution is peaked at $\approx 0^{\circ}$ as expected for no birefringence and it can be modelled by two populations: one which is a Gaussian with mean $μ_β=(0.2\pm 1.0)^{\circ}$ and standard deviation $σ_β=(14.7\pm 1.1)^{\circ}$ and the other a uniform distribution of sources which are a fraction $f_β=0.72\pm 0.02$ of the total. Uncertainties in $μ_β$ can be reduced to $\approx 0.6^{\circ}$ by stacking measurements of the PA from other wavebands. We find that limits of $\approx 0.1^{\circ}$ might be possible with a sample of $\sim 10^5$ similarly selected sources and that this could provide a confirmation of recent claims of global birefringence made using the Cosmic Microwave Background observations from the {\it Planck} satellite.
[abstract 70 / 92] (score: 2) - Title: Semi-analytical model for the rising sheet generated by droplet-pair impactAuthors: Shushan Hu, Liwu Fan, Nan Hu,Comments:Subjects: physics.flu-dynCreated: 2026-07-02; Updated: 2026-07-07; Datestamp: 2026-07-07
When two low-Ohnesorge-number drops impact a dry substrate simultaneously, their spreading lamellae collide and lift a free-standing vertical sheet. The sheet grows by inertial feeding from the spreading drops and is pulled back by capillary retraction at its rim. We develop a semi-analytical model for this rising sheet by extending the single-drop impact description of~\citet{Gordillo2019} to the two-drop geometry. The thin-film flow in the sheet is coupled at its base to the colliding lamellae and at its apex to a capillary-retarded rim. The sheet interior is then solved along ballistic characteristics in two stages: a lamella-fed stage, for which the velocity and thickness fields can be obtained in closed form, and a post-lamella stage, for which the inlet conditions are taken from simulations. The resulting framework gives the three-dimensional velocity and thickness fields and therefore the full sheet shape. On the centreline, the apex height and local thickness are obtained explicitly, showing that the different Weber-number exponents reported in the literature arise from a crossover rather than from a single universal scaling law. At sufficiently large Weber number, the apex pinches off. A linear Rayleigh--Plateau analysis, using the time-dependent JET diameter and deceleration predicted by the model, then bounds the maximum attainable height and closes the description of the pinch-off regime.
[abstract 71 / 92] (score: 2) - Title: Small-scale dynamo saturation across MAGNETic Prandtl numbers using the EDQNM closureAuthors: Muhammed Irshad, Kandaswamy Subramanian, Pallavi Bhat,Comments: 13 pages, 19 figures (excluding appendix). Comments are welcomeSubjects: astro-ph.GA astro-ph.SR physics.flu-dyn physics.plasm-phCreated: 2026-07-02; Updated: 2026-07-07; Datestamp: 2026-07-07
Small-scale dynamos (SSDs) are believed to be the primary source of MAGNETic fields in all turbulent astrophysical systems, especially those with weak rotation such as elliptical galaxies and galaxy clusters. The initial kinematic phase of these dynamos is relatively well understood. Here we demonstrate analytically and numerically that, in an appropriate limit, the eddy-damped quasi-normal Markovian (EDQNM) closure for incompressible MAGNETohydrodynamic turbulence is strictly equivalent to the earlier models of kinematic dynamos. Moreover, it allows the extension of the kinematic dynamo framework to multi-scale turbulent flows and into the nonlinear regime. The EDQNM closure also enables us to explore a wide parameter range which is inaccessible to direct numerical simulations of the SSD. Using nonhelical EDQNM simulations, we identify several asymptotic regimes of nonlinear dynamo action when the system is highly turbulent with fluid Reynolds number $Re \gtrsim 10^6$ for MAGNETic Prandtl number $Pm > 1$ and MAGNETic Reynolds number $Rm \gtrsim 10^6$ for $Pm < 1$: 1) the kinematic growth rate approaches a value independent of $Pm$, 2) the saturated MAGNETic to kinetic energy ratio similarly converges to $\simeq 0.55$ across $Pm$, while the ratio of MAGNETic to kinetic integral wavenumbers asymptotes to $\simeq 3$. For all $Pm$, we further find strong feedback between MAGNETic field and velocity field largely via Alfvénisation leading to a saturated kinetic and MAGNETic spectra with almost the same inertial range with a slope of $-3/2$. These findings could provide guidance for future global simulations and for modeling the nonlinear regime of astrophysical systems living in these extreme limits.
[abstract 72 / 92] (score: 2) - Title: No Strong Evidence for Plasma Lensing in FRB 20240114AAuthors: Jiarui Niu, Xiaohui Liu, Nan Xu, Songyu Shen, Junshuo Zhang, Tiancong Wang, Pawan Kumar, Yuanhong Qu, Dejiang Zhou, Weiwei Zhu, Bing Zhang, He Gao, Dongzi Li, Jinlin Han, Di Li, Xuelei Chen, Kejia Lee, Ye Li, Weiyang Wang, Qiuyang Fu, Jiawei Jin, Yanqing Cai, Caisong Liu, Shuo Cao, Ziwei Wu, Heng Xu, Dengke Zhou, Longxuan Zhang, Wanjin Lu, Yi Feng, Chenhui Niu, Jiawei Luo, Rui Luo, Chunfeng Zhang, Shiqian Zhao, Chengwei Liang,Comments: 15 pages, 5 figures; submitted for publicationSubjects: astro-ph.HECreated: 2026-07-03; Updated: 2026-07-07; Datestamp: 2026-07-07
FRB~20240114A is an extremely active repeating fast radio burst for which plasma lensing has been proposed to explain its burst-rate variations, spectral evolution, and apparently ``carbon-copy'' burst pairs. Using FAST data and publicly available Parkes observations, we test this interpretation with a one-dimensional Gaussian plasma-lens model. Although the burst-rate enhancements can be fitted separately, the corresponding magnification peaks and demagnification troughs are offset by far more than predicted and show no consistent periodicity. Moreover, with more than 10,000 bursts detected, a few apparently ``carbon-copy'' pairs can readily occur by chance. The burst bandwidth is not systematically narrower during the proposed lensing interval, nor are the burst energies significantly enhanced during the predicted magnification interval. These results provide no compelling evidence that a single Gaussian plasma lens explains the observed variability, which is more likely dominated by intrinsic source activity.
[abstract 73 / 92] (score: 2) - Title: FAST Pulsar Database III. Snapshots of nulling, mode-changing and subpulse modulation of 374 pulsarsAuthors: Yi Yan, J. L. Han, J. Xu, N. N. Cai, W. Q. Su, P. F. Wang, C. Wang, T. Wang, D. J. Zhou, W. C. Jing, Z. L. Yang,Comments: 310 pages, 922 figuresSubjects: astro-ph.HECreated: 2026-07-03; Updated: 2026-07-07; Datestamp: 2026-07-07
Based on sensitive L-band (1.0 to 1.5 GHz) observations of pulsars using the Five-hundred-meter Aperture Spherical radio Telescope (FAST), we analyzed single-pulse sequences from FAST-detected pulsars and identified nulling, mode changing, or subpulse modulation phenomena in 374 sources. Among these, nulling has been detected in 160 pulsars, with 127 cases reported for the first time. Emission mode changes have been observed in 52 pulsars, including 51 first-time detections. Subpulse modulation has been identified in 272 pulsars, 180 of which are newly revealed, with the majority displaying subpulse drifting behavior. Subpulse drifting in some pulsars exhibits distinct modes with varying drift properties, leading to mode changes and divergent mean profiles. Statistics on pulsar parameters show that pulsars exhibiting nulling and/or subpulse modulation tend to be older, with longer periods and lower spin-down energy-loss rates. The modulation period P3 is predominantly correlated with pulsar rotation periods, MAGNETic field strengths, and spin-down energy loss.
[abstract 74 / 92] (score: 2) - Title: Understanding the Neutron Star Population with the SKAO TelescopesAuthors: L. Levin, M. Bagchi, M. Burgay, A. T. Deller, V. Graber, A. Igoshev, M. Kramer, D. Lorimer, B. Posselt, T. Prabu, K. Rajwade, N. Rea, B. Stappers, T. M. Tauris, P. Weltevrede,Comments: Published in Advancing Astrophysics with the SKA II (AASKAII), 2026 (arXiv:2606.20366). Report number AASKAII/Levin01. Advancing Astrophysics with the SKA II (AASKAII) outlines the transformative scientific advances that will be enabled by the SKA telescopes. An earlier version of this chapter was published in The Open Journal of Astrophysics with arXiv ID: arXiv:2512.16156Subjects: astro-ph.HECreated: 2026-07-03; Updated: 2026-07-07; Datestamp: 2026-07-07
The known population of non-accreting neutron stars is ever growing and currently consists of more than 3500 sources. Pulsar surveys with the SKAO telescopes will greatly increase the known population, adding radio pulsars to every subgroup in the radio-loud neutron star family. These discoveries will not only add to the current understanding of neutron star physics by increasing the known sample, but will undoubtedly also uncover new types of sources that will challenge our theories of a wide range of physical phenomena. A broad variety of scientific studies will be made possible by a significantly increased population of neutron stars, unravelling questions such as: How do isolated pulsars evolve with time; What is the connection between MAGNETars, high B-field pulsars, and the newly discovered long-period pulsars; How is a pulsar's spin-down related to its radio emission; What is the nuclear equation of state? Increasing the numbers of pulsars in binary systems enables both larger numbers and higher precision tests of gravitational theories and general relativity, as well as probing the neutron star mass distribution. The excellent sensitivity of the SKAO telescopes combined with the wide field of view, large numbers of simultaneous tied-array beams that will be searched in real time, wide range of observing frequencies, and the ability to form multiple sub-arrays will make the SKAO an excellent facility for neutron star research. This chapter presents an overview of different types of neutron stars and discusses how the SKAO will aid in our understanding of the neutron star population.
[abstract 75 / 92] (score: 2) - Title: A Square Kilometre Array Pulsar CensusAuthors: E. F. Keane, V. Graber, L. Levin, C. M. Tan, O. A. Johnson, C. Ng, C. Pardo-Araujo, M. Ronchi, D. Vohl, M. Xue,Comments: Published in Advancing Astrophysics with the SKA II (AASKAII), 2026 (arXiv:2606.20366). Report-no: AASKAII/Keane01. Advancing Astrophysics with the SKA II (AASKA II) outlines the transformative scientific advances that will be enabled by the SKA telescopes. An earlier version of this chapter was published in The Open Journal of Astrophysics with arXiv ID: arXiv:2512.16153Subjects: astro-ph.HECreated: 2026-07-03; Updated: 2026-07-07; Datestamp: 2026-07-07
Most of the pulsar science case with the Square Kilometre Array (SKA) depends on long-term precision timing of a large number of pulsars, as well as their astrometric measurements using very long baseline interferometry (VLBI). However, before we can time them, or VLBI them, we must first find them. Here, we describe the considerations and strategies needed when planning an all-sky blind pulsar survey using the SKA. Based on our understanding of the pulsar population, the performance of the now-under-construction SKA elements, and practical constraints such as evading radio frequency interference, we project pulsar survey yields; this is done using two complementary methods for a number of illustrative survey designs, combining SKA-Low and SKA-Mid Bands 1 and 2 in a variety of ways. A composite survey using both SKA-Mid and SKA-Low is optimal, with Mid Band 2 focused in the plane. We find that, given its much higher effective area and survey speed, the best strategy is to use SKA-Low to cover as much sky as possible, ideally also overlapping with the areas covered by Mid. We find that an all-sky blind survey with Phase 1 of the SKA with the AA* array assembly will detect $\sim10,000$ slow pulsars and $\sim 800$ millisecond pulsars (MSPs) if SKA-Mid covers the region within $5°$ of the plane, while higher latitudes will be covered with SKA-Low. For the same survey region the yield with AA4 is $\sim 20\%$ higher, but this increases considerably by broadening the range covered by SKA-Mid Bands 1 and 2. In particular one could expect a yield of $\sim 1300$ MSPs with AA4. The pulsar census will enable us to set new constraints on the uncertain physical properties of the entire neutron star population. This will be crucial for addressing major SKA science questions including the dense-matter equation of state, strong-field gravity tests, and gravitational wave astronomy.
[abstract 76 / 92] (score: 2) - Title: Exceptional light propagation via generalized bulk-edge correspondenceAuthors: Heitor da Silva, Sergey K. Ivanov, Isaac Suárez, José R. Salgueiro, Albert Ferrando,Comments:Subjects: physics.opticsCreated: 2026-07-03; Updated: 2026-07-07; Datestamp: 2026-07-07
In topological photonics, the bulk-edge correspondence is conventionally imported by direct analogy with electronic systems, overlooking the fundamentally distinct spacetime symmetries of Maxwell's and Schrödinger's equations. In this work, we challenge this prevailing paradigm by demonstrating that non-trivial bulk topology alone is insufficient to guarantee localized edge states in photonic platforms. Using a Su-Schrieffer-Heeger-inspired photonic crystal, we unveil a generalized bulk-edge correspondence intrinsically shaped by the RELATIVISTIC nature of electroMAGNETic waves. This constraint imposes a strict frequency cutoff, a feature fundamentally absent in electronic topological insulators, which enables a new regime of frequency-controlled spatial localization near the cutoff. Furthermore, we demonstrate that this generalized correspondence is POLARIZATION-dependent: transverse electric (TE) and transverse MAGNETic (TM) edge modes exist in different parameter regimes and exhibit distinct dispersion relations, including distinct zero-dispersion points. Our framework redefines the theoretical boundaries of topological photonics, unlocking new opportunities for POLARIZATION-selective dispersion engineering and robust pulse propagation in topological photonic platforms.
[abstract 77 / 92] (score: 2) - Title: Exploring the Magnetic Field Structure of the Milky Way with Pulsars in the SKA EraAuthors: Jun Xu, J. L. Han, Weicong Jing,Comments: Published in Advancing Astrophysics with the SKA II (AASKAII), 2026 (arXiv:2606.20366). Report-no: AASKAII/JunXu01. Advancing Astrophysics with the SKA II (AASKAII) outlines the transformative scientific advances that will be enabled by the SKA telescopes. An earlier version of this chapter was published in The Open Journal of Astrophysics with arXiv ID: arXiv:2512.16159Subjects: astro-ph.HE astro-ph.GACreated: 2026-07-03; Updated: 2026-07-07; Datestamp: 2026-07-07
The MAGNETic field structure of the Milky Way can offer critical insights into the origin of galactic MAGNETic fields. Measurements of MAGNETic structures of the Milky Way are still sparse in far regions of the Galactic disk and halo. Pulsars are the best probes for the three-dimensional structure of the Galactic MAGNETic field, primarily owing to their highly polarized short-duration radio pulses, negligible intrinsic Faraday rotation compared to the contribution from the medium in front, and their widespread distribution throughout the Galaxy across the thin disk, spiral arms, and extended halo. In this article, we give an overview of Galactic MAGNETic field investigation using pulsars. The sensitive SKA1 design baseline (AA4) will increase the number of known pulsars by a factor of around three, and the initial staged delivery array (AA*) will probably double the total number of the current pulsar population. Polarization observations of pulsars with the AA* telescopes will give rotation measures along several thousand lines of sight, enabling detailed exploration of the MAGNETic structure of both the Galactic disk and the Galactic halo.
[abstract 78 / 92] (score: 2) - Title: Hubble constant measurement with 13 bright standard sirens from binary BLACK HOLE mergers inside ACTIVE GALACTIC NUCLEiAuthors: Dhruv Kumar, Alejandro Torres-Orjuela,Comments: 4 pages, 2 figures, 1 tableSubjects: astro-ph.CO gr-qcCreated: 2026-07-04; Updated: 2026-07-07; Datestamp: 2026-07-07
We measure the Hubble constant $H_0$ using 13 gravitational-wave binary BLACK HOLE mergers associated with ACTIVE GALACTIC NUCLEus hosts. We find $H_0=70.50^{+3.37}_{-2.89}\,({\rm stat})\pm1.56\,({\rm cal})$\,km\,s$^{-1}$\,Mpc$^{-1}$ ($4.4\%$ precision), consistent with both Planck\,2018 ($0.98σ$) and SH0ES\,2024 ($0.76σ$), with no significant preference between the two. Combining with the bright siren GW170817 sharpens the constraint to $H_0=70.31^{+3.00}_{-2.85}\,({\rm stat})\pm1.55\,({\rm cal})$\,km\,s$^{-1}$\,Mpc$^{-1}$ ($4.2\%$ precision), and further combining with an independent dark-and-bright-siren sample tightens it to $H_0=69.71^{+2.55}_{-2.40}\,({\rm stat})\pm1.54\,({\rm cal})$\,km\,s$^{-1}$\,Mpc$^{-1}$ ($3.5\%$ precision). Assuming a luminosity-distance prior centered around the value related to a fixed cosmology in turn, recovers $H_0=67.62\pm0.72$ (Planck-anchored) and $H_0=72.91\pm0.72$\,km\,s$^{-1}$\,Mpc$^{-1}$ (SH0ES-anchored). We show that under such an assumption, a rejection of $\gtrsim4σ$ to the opposing anchor is obtained.
[abstract 79 / 92] (score: 2) - Title: A NICER view of the millisecond pulsar PSR J2124$-$3358: evidence for a helium atmosphereAuthors: Denis González-Caniulef, Sebastien Guillot, Pierre Stammler, Lucien Mauviard, Christine Kazantsev, Anna L. Watts, Devarshi Choudhury, Bas Dorsman, Mariska Hoogkamer, Daniela Huppenkothen, Yves Kini, Tuomo Salmi, Lucas Guillemot, Ismaël Cognard, Gilles Theureau,Comments: 21 pages, 9 figures and 3 tables. Submitted to ApJ. Supplementary data products are available in ZenodoSubjects: astro-ph.HECreated: 2026-07-04; Updated: 2026-07-07; Datestamp: 2026-07-07
Pulse profile modeling has proven to be a powerful technique for determining the mass and radius of neutron stars. To date, this method has been applied to a handful of millisecond pulsars observed by the Neutron Star Interior Composition Explorer (NICER). However, analyses of more millisecond pulsars are necessary to determine tight constraints on the equation of state of superdense matter. In this study, we present an analysis of the isolated, rotation-powered millisecond pulsar PSR J2124$-$3358 using the X-ray Pulse Simulation and Inference (X-PSI) package, a publicly available state-of-the-art code for neutron-star RELATIVISTIC ray tracing and Bayesian parameter inference. We use NICER and Chandra observations of this pulsar, exploring different neutron star atmospheric compositions and different configurations of the hot polar caps responsible for the pulsed X-ray emission. Our analyses favor a helium atmospheric composition, plausibly originating from accretion and subsequent evaporation of a former hydrogen-depleted binary companion. For this composition, and given the faint nature of the source and the low signal-to-noise of the data sets, we obtain broad posterior distributions yielding a mass $M = 1.8\pm0.5\,M_\odot$ and an equatorial radius $R_{\mathrm{eq}} = 11.7^{+2.6}_{-3.0}$ km (medians and $68\%$ credible intervals), and infer a configuration consisting of two slightly non-antipodal hot spots. By contrast, when using a hydrogen atmosphere model, the mass and radius decrease by $\sim 0.5\,M_\odot$ and $\sim 1$ km, respectively. Future multiwavelength studies, particularly those incorporating radio and gamma-ray pulse-emission, may provide tighter constraints on the geometry and physical properties of this source.
[abstract 80 / 92] (score: 2) - Title: Star Planet InteractionsAuthors: Arghyadeep Paul, Kristina Kislyakova, Manuel Güdel, Rim Fares, Judy Chebly, Sergio Joya, Miljenko Čemeljić, Katja Poppenhäger, Julian Alvarado-Gomez, Silva Järvinen, Cesar Bertucci, Dibyendu Nandy, Antonio García Muñoz, Antoine Strugarek, Mayank Narang, Shyama Narendranath,Comments: Submitted to Space Science ReviewsSubjects: astro-ph.SR astro-ph.EPCreated: 2026-07-04; Updated: 2026-07-07; Datestamp: 2026-07-07
Star-planet interactions (SPIs) describe the continuous exchange of energy, momentum, and mass between exoplanets and their host stars through radiative, tidal, MAGNETic, and particle-driven processes. Together, these interactions shape the structure, evolution, and observable properties of exoplanetary systems. In this review, we bring together current theoretical and observational understanding of SPIs, highlighting how stellar radiation, winds, and MAGNETic activity influence planetary atmospheres, interiors, and orbital evolution, while using the Solar System as a valuable reference for interpreting these processes. High-energy stellar radiation, particularly in the far- and extreme-ultraviolet and X-ray bands, drives atmospheric heating, photochemistry, ionisation, and escape. These effects are further influenced by stellar winds and MAGNETic interactions, which can either protect planetary atmospheres or accelerate their loss over time. Tidal interactions redistribute energy and angular momentum, producing internal heating and driving orbital migration and circularisation. Magnetic star-planet coupling provides additional pathways for energy transfer through RECONNECTion and current systems, potentially enhancing atmospheric escape, heating planetary ionospheres and interiors, and generating observable signatures such as radio emission and enhanced stellar activity. We discuss how these processes work together, emphasising that their long-term impact depends on stellar evolution, planetary properties, atmospheric structure, and MAGNETic field strength. By presenting radiative, tidal, and MAGNETic interactions within a unified framework, this review highlights the physical mechanisms that shape planetary environments and identifies the key observational signatures that will complement future studies of exoplanet evolution and habitability.
[abstract 81 / 92] (score: 2) - Title: Cross-validation of six dispersion measure estimation methods for FRB 20240114AAuthors: Tonglun Wang, Songbo Zhang, Yuanchuan Zou, Xuan Yang, Pei Wang, Di Xiao, Xianghan Cui, Ye Li, Hao Qiu, Yingze Shan, Junyi Shen, Ya Zeng, Longxuan Zhang, Wenlong Zhang,Comments: 13 pages, 16 figuresSubjects: astro-ph.HECreated: 2026-07-04; Updated: 2026-07-07; Datestamp: 2026-07-07
Fast Radio Bursts (FRBs) are important cosmological probes, but their applications depend critically on accurate dispersion measure (DM) determinations. We present a systematic comparison of six DM estimation methods using 2,874 bursts from FRB20240114A, the most active repeating FRB currently known, observed by FAST during a single 4.4-hr session on 2024 March 12. This large, homogeneous sample over a short timescale, during which the propagation environment is expected to be nearly static, provides an ideal benchmark for isolating algorithmic effects on DM determination. We investigate the dependence of inter-method consistency on signal-to-noise ratio (S/N), burst morphology, and radio frequency interference (RFI). Low-S/N bursts exhibit significantly larger inter-method deviations, while single-component bursts produce highly consistent DM values across methods. In contrast, complex double- and multiple-component bursts with drifting substructures lead to substantial inter-method scattering, indicating that DM discrepancies are primarily driven by algorithmic responses to burst morphology. RFI does not significantly alter the global statistical behavior of DM deviations, but it affects density-filtering methods through morphology distortion caused by frequency-channel masking. Even after imposing strict inter-method consistency constraints, FRB20240114A still exhibits notable apparent DM fluctuations spanning $\sim$528-534~pc~cm$^{-3}$ over 15,780s. For morphologically simple bursts these variations far exceed the measurement uncertainty and, on second-to-minute timescales, cannot arise from any plausible change in the line-of-sight electron column, pointing instead to a frequency-dependent emission-time structure intrinsic to the bursts that mimics dispersion.
[abstract 82 / 92] (score: 2) - Title: Widespread Detection of Aromatic and Aliphatic Emission in the Dual Quasar J0749+2255 at Cosmic NoonAuthors: C. E. Mentzer, Aigen Li, X. J. Yang,Comments: 19 pages, 6 figures; accepted for publication in The Astrophysical Journal LettersSubjects: astro-ph.GACreated: 2026-07-04; Updated: 2026-07-07; Datestamp: 2026-07-07
Based on JWST/MIRI integral field observations, we report a widespread detection of aromatic and aliphatic hydrocarbon emission at rest-frame 3.3 and 3.4 micron in SDSSJ074922.96+225511.7 (hereafter J0749+2255), a dual QUASAR at redshift z~2.17, corresponding to a cosmic age of ~3 billion years after the Big Bang, a time period known as the "cosmic noon" when STAR FORMATION and BLACK HOLE growth peak. With the 3.3 micron emission ascribed to aromatic C--H stretches of small PAH molecules and the 3.4 micron emission assigned to aliphatic C--H stretches of aliphatic sidegroups attached to PAHs, we utilize the observed intensities of the 3.3 and 3.4 micron emission bands to estimate the aliphatic fractions of PAHs and their variations across J0749+2255, which is, to our knowledge, the most distant object to date in which both aromatics and aliphatics have ever been detected. We find that both the 3.3 and 3.4 micron emission bands are pronounced and the aliphatic fractions are surprisingly high in the most luminous regions centered on the two QUASAR nuclei, suggesting that not only small PAHs (of ~20--30 carbon atoms) but also their attached aliphatic sidegroups survive in intense ultraviolet radiation arising from extreme starburst.
[abstract 83 / 92] (score: 2) - Title: Production of high-quality plasma discharges via real-time control of plasma current ramp-up using neutral gas injection in Aditya-U tokamakAuthors: Suman Dolui, Praveenlal Edappala, Kaushlender Singh, J. Ghosh, R. L. Tanna, A. Kundu, K. A. Jadeja, Ankit Patel, Rohit Kumar, Suman Aich, Harshita Raj, K. M. Patel, M. B. Chowdhuri, P. K. Chattopadhyay, A. Sen, R. Pal,Comments: 10 pages, 4 figuresSubjects: physics.plasm-phCreated: 2026-07-04; Updated: 2026-07-07; Datestamp: 2026-07-07
Robust control of plasma current ramp-up is an absolute necessity, as an efficient and uncontaminated plasma current ramp-up is essential for achieving prolonged, high-pressure tokamak plasma discharges. In conventional tokamaks with Ohmic breakdown, the plasma current ramp-up is achieved primarily with pre-fixed temporal profiles of the applied toroidal electric field and the equilibrium MAGNETic field (Bv). The pre-fixed temporal profiles of these fields are often insufficient to maintain a successful plasma current ramp-up, as several unquantified dynamical variables, such as the condition of the vessel wall and plasma-facing components, influence the plasma current rise. Fuel gas injection in an appropriate quantity at a suitable time during the current ramp-up is therefore used to control the plasma current rise rate, ensuring successful plasma current start-up in Aditya-U. The gas injection time and gas quantity are controlled based on real-time measurement of plasma current rise rate using a digital signal processor (DSP) controller. This special control scheme is capable of achieving the plasma current to rise nearly at the desired rate, resulting in a successful start-up and a stable plasma discharge.
[abstract 84 / 92] (score: 2) - Title: Measuring the Angular Auto-power Spectrum of Fast Radio Burst Dispersion Measures as a Robust Cosmological Probe and Baryon TracerAuthors: Bao Wang, Zhiyu Lu, Yang Liu, Jun-Jie Wei, Xue-Feng Wu,Comments: 13 pages, 6 figuresSubjects: astro-ph.HE astro-ph.COCreated: 2026-07-05; Updated: 2026-07-07; Datestamp: 2026-07-07
Fluctuations in the cosmic electron density are imprinted on the dispersion measures (DMs) of fast radio bursts (FRBs), making DMs a promising probe of cosmology and the spatial distribution of ionized baryons. In this work, we present the first measurement of the angular auto-power spectrum of FRB DMs, using 3455 apparently non-repeating bursts from the CHIME/FRB Catalog 2. We detect an angular correlation signal at $>3σ$ significance, associated with large-scale electron-density fluctuations. By fitting the measured spectrum to theoretical models, we constrain two key parameter combinations: $Ω_{\rm b}h^2$-$H_0$, which probes the cosmic baryon density and expansion rate, and $Ω_{\rm b}h^2$-$f_{\rm d}$, which traces the baryon fraction in cosmic large-scale structure (LSS). We further assess the robustness of the power-spectrum method against systematic uncertainties arising from the assumed FRB redshift distribution and from the DM contributions of host galaxies (${\rm DM}_{\rm host}$), the Galactic halo (${\rm DM}^{\rm MW}_{\rm halo}$), and the Milky Way interstellar medium (${\rm DM}^{\rm MW}_{\rm ISM}$), using mock samples. Our results demonstrate that the angular power spectrum is largely insensitive to uncorrelated DM components such as ${\rm DM}_{\rm host}$, thereby effectively mitigating the impact of poorly constrained host-galaxy systematics. In contrast to the traditional ${\rm DM}_{\rm LSS}$-$z$ relation, this method does not require individual redshift measurements--it relies only on the overall redshift distribution--and it partially breaks the parameter degeneracies in the $Ω_{\rm b}h^2$-$H_0$ and $Ω_{\rm b}h^2$-$f_{\rm d}$ planes. These findings establish the DM angular power spectrum as a robust cosmological probe and a powerful baryon tracer.
[abstract 85 / 92] (score: 2) - Title: Probing Flare-Associated Eruptions on AB Doradus via X-ray Absorption VariationsAuthors: Shweta Didel, Jeewan C Pandey, Abhishekh K Srivastava,Comments: 16 pages, 2 figures, Accepted for publication in Philosophical Transactions ASubjects: astro-ph.SR astro-ph.HECreated: 2026-07-05; Updated: 2026-07-07; Datestamp: 2026-07-07
In this work, we investigate eruptive phenomena associated with X-ray flares on AB Doradus using observations from XMM-Newton. Our aim is to detect such events with the help of continuous X-ray absorption. The variation in the hydrogen column density (NH) is used as a primary diagnostic to detect such absorption or spectral hardening in the soft X-ray band below 1 - 2 keV. These variations may represent the signatures of the eruptive processes associated with flares, such as stellar prominences, failed eruptions, or coronal mass ejections. We applied time-resolved spectroscopy technique to track changes in the absorption parameter during flaring episodes. Our analysis shows statistically significant enhancements in the NH, spanning from 0.3 - 3.4 x 10^20 cm^-2 during the flare and post-flare intervals. Out of six data sets, two sets containing multiple-overlapped flares show significant fluctuations and remaining showed no such variations in NH. These variations indicate the presence of dynamic absorbing material along the line of sight and point to ongoing physical processes within the stellar corona.
[abstract 86 / 92] (score: 2) - Title: Particle dynamics and confinement in moving multi-mirrorAuthors: Tal Miller, Eli Gudinetsky, Ilan Be'ery, Ido Barth,Comments:Subjects: physics.plasm-phCreated: 2026-07-05; Updated: 2026-07-07; Datestamp: 2026-07-07
The moving multi-mirror (MMM) concept mitigates axial losses in MAGNETic mirrors by using inward-propagating multi-mirror sections to transport escaping particles back toward the central cell. Single-particle simulations are used to establish the underlying dynamics, while a modified rate-equation model provides quantitative estimates of the resulting confinement enhancement. It is found that the steady-state outgoing flux can be robustly suppressed by several orders of magnitude. The analysis uncovered confinement challenges in the MMM concept, indicating that additional scattering processes are required in both the central cell and the MMM sections to achieve the desired confinement.
[abstract 87 / 92] (score: 2) - Title: Turbulent Magnetogenesis and Large-scale Magnetic Dynamo Amplification in Ion--electron PlasmasAuthors: Fabio Bacchini, Francesco Pucci, Sergio Servidio, Francesco Valentini, William H. Matthaeus,Comments:Subjects: physics.plasm-ph astro-ph.CO astro-ph.GA astro-ph.SRCreated: 2026-07-05; Updated: 2026-07-07; Datestamp: 2026-07-07
Using fully kinetic simulations that capture unprecedentedly large (from electron to ion) scales, we study MAGNETogenesis driven by continuous large-scale forcing until nonlinear dynamo saturation. We uncover a two-stage mechanism in collisionless ion-electron plasmas whose dynamics diverge dramatically from the pair-plasma case. In the first phase, electron pressure anisotropy triggers electron-Weibel modes, seeding small-scale MAGNETic fields. Then, a second growth phase emerges when the more massive ions develop their own strong anisotropy and drive ion-Weibel-type modes; concurrently, a Biermann-battery mechanism contributes to amplifying the MAGNETic field. This combined dynamics provides a tenfold amplification of the MAGNETic field in comparison to the pair-plasma case. Over long times, dynamo action continues until the system reaches a statistical steady state. This self-consistent kinetic mechanism provides a plausible explanation for robust MAGNETogenesis wherever an external forcing continuously stirs the plasma.
[abstract 88 / 92] (score: 2) - Title: Hyper Boris integrators for kinetic plasma simulations and their connection to 3D rotation representationsAuthors: S. Zenitani, T. N. Kato,Comments: 4 pages; proceedings of the 52nd EPS Conference on Plasma Physics (June 29 -- July 3, 2026, Edinburgh, UK)Subjects: physics.comp-ph physics.plasm-phCreated: 2026-07-05; Updated: 2026-07-07; Datestamp: 2026-07-07
Particle-in-cell (PIC) simulation is one of the most important research tools in theoretical plasma physics. To solve the motion of charged particles, the Boris method (a.k.a. the Boris integrator/pusher/solver) has been used for more than a half century. Although the Boris solver has good accuracy, the demand for high-accuracy numerical solvers has been increasing, and new integrators have been actively developed. In this contribution, we present novel high-accuracy particle integrators, the hyper Boris integrators, for nonRELATIVISTIC kinetic simulations. We further discuss their connection to 3D rotation representations.
[abstract 89 / 92] (score: 2) - Title: Beyond the Bounce: Multiple Tidal Sign Reversals and Turning-Point Bifurcations in Multi-Horizon Black HolesAuthors: Mohammad Ali S. Afshar, J. Sadeghi,Comments: 20 pages, 20 figures, 2 TableSubjects: gr-qcCreated: 2026-07-06; Updated: 2026-07-07; Datestamp: 2026-07-07
We investigate the radial motion and tidal forces experienced by neutral test particles in multi-horizon BLACK HOLE solutions arising from Einstein gravity coupled to nonlinear electrodynamics (NED). Focusing on the three- and four-horizon configurations, we examine how nonlinear electroMAGNETic corrections modify the causal structure, radial geodesic motion, and tidal-force profiles in comparison with the Schwarzschild and Reissner-Nordstrom (R-N) spacetimes. Our analysis shows that the NED field gives rise to multiple zero crossings in both the radial and angular tidal-force components, leading to successive transitions between stretching and compressive tidal regimes. More importantly, the radial equation of motion contains classically forbidden regions bounded by bounce-back points. For the class of trajectories considered in this work, these forbidden regions prevent particles from entering the spacetime domain where the tidal forces become divergent. In the super-extremal regime admitted by these solutions, the forbidden region may extend beyond the event horizon, preventing particles released from rest at sufficiently large distances from crossing the horizon. We further identify a systematic ordering of the critical charge values associated with the appearance of tidal-force zero crossings, additional horizons, and bounce-back points. For both the three- and four-horizon configurations, these critical values satisfy a hierarchical ordering, indicating that changes in the tidal-force structure precede the corresponding modifications of the horizon configuration. These results demonstrate that nonlinear electrodynamics can substantially modify the classical dynamics of neutral particles in multi-horizon BLACK HOLE spacetimes through the combined effects of forbidden regions, multiple tidal transitions, and changes in the horizon structure.
[abstract 90 / 92] (score: 2) - Title: On the electroMAGNETic effects of collisionless trapped-electron modesAuthors: Yao Yao, Haotian Chen, Yang Chen, Jiquan Li, Xuru Duan,Comments: 17 pages, 6 figures, submitted to Nuclear FusionSubjects: physics.plasm-phCreated: 2026-07-06; Updated: 2026-07-07; Datestamp: 2026-07-07
We present a linear gyrokinetic theory for the electroMAGNETic collisionless trapped-electron mode (CTEM). It is found that the weak electroMAGNETic effects of CTEMs originate from the particle dynamics. Theoretical analysis reveals that the kinetic and fluid-like components of the trapped-electron parallel current cancel at leading order. The ion parallel current is also negligible due to the weak ion transit resonance. Consequently, the perturbed parallel current in the electroMAGNETic CTEM is dominated by passing electrons. We demonstrate that these characteristics of particle dynamics decouple the CTEM from the shear Alfvén wave branch, rendering the electroMAGNETic effects subdominant. Both eigenmode analyses and gyrokinetic simulations validate these findings.
[abstract 91 / 92] (score: 2) - Title: Emulation of non-linear 1D spectral models: RELATIVISTIC X-ray reflectionAuthors: Benjamin J. Ricketts, Tin Hadži Veljković, Daniela Huppenkothen, Adam Ingram, Matteo Lucchini, Guglielmo Mastroserio, Fergus J. E. Baker,Comments: 16 pages, 13 figures, submitted to Royal Astronomy Society Techniques and Instruments (RASTI), comments welcomeSubjects: astro-ph.IM astro-ph.HECreated: 2026-07-06; Updated: 2026-07-07; Datestamp: 2026-07-07
The use of machine learning techniques to approximate computationally expensive models has become increasingly prevalent in a wide variety of fields within astronomy. We discuss the implementation of emulators for 1-dimensional models in the context of the astrophysical numerical model reltrans, a BLACK HOLE X-ray spectral model that models the effects of RELATIVISTICally smeared emission from an accretion disk. We argue that the decision of whether and how to emulate should follow from a systematic characterisation of the target model, and we demonstrate a diagnostic workflow: examining how the spectrum varies with individual parameters. We adopt a modular strategy, emulating only the RELATIVISTICally convolved reflection spectrum (1-10% of the total flux) rather than the full model. Using an operator-learning architecture with Fourier feature embeddings and FiLM conditioning, we reproduce the reflection spectrum to O(0.1)% precision across 0.1-100 keV with a 4-10x speed-up that scales considerably better under vectorised evaluation. This emulator, RTFAST2, recovers the true parameters of simulated observations without the systematic posterior biases of our previous work. We conclude that no architecture is universally transferable and bespoke emulators motivated by a model's specific structure are required. The modular approach taken in this work presents a promising strategy for future emulators of numerical models.
[abstract 92 / 92] (score: 2) - Title: ALMA observations of Magnetic Fields in the Massive Star-forming Region IRAS 18360-0537Authors: Shixian Mo, Keping Qiu, Qizhou Zhang, Junhao Liu, Josep Miquel Girart, Hauyu Baobab Liu, Zhi-Yun Li, Shanghuo Li, Huei-Ru Vivien Chen,Comments: 25 pages,10 figursSubjects: astro-ph.GACreated: 2026-07-06; Updated: 2026-07-07; Datestamp: 2026-07-07
Assessing the significance of MAGNETic fields in high-mass STAR FORMATION remains one of the most challenging topics in astrophysics. In this study, we present full POLARIZATION observations obtained from the Atacama Large Millimeter/Submillimeter Array (ALMA) of the high-mass star-forming region IRAS18360-0537. The polarized dust emission at 1.3 mm reveals a clear hourglass-shaped morphology of the MAGNETic field. Interestingly, the MAGNETic field orientation is nearly perpendicular to both the outflow and core rotation axes, while it aligns with the elongation of the core. This orientation poses challenges for interpretation, particularly in light of the strong MAGNETic field strength estimated using the Davis-Chandrasekhar-FERMI method. Several scenarios provide insights into the underlying reasons for this MAGNETic field morphology. A clear velocity gradient seen in high-density tracing of molecular spectral lines indicates that the core is fast-rotating. The curved outskirts of the MAGNETic fields coincide with the outflow cavity, suggesting a possible influence from the outflow. The accretion flows along the core's elongation are also notable. Our study shows that the morphology of the MAGNETic field is probably highly influenced by the gas bulk motions.
arXiv:2603.15028 [pdf, ps, other]
arXiv:2607.04666 [pdf, ps, other]
arXiv:2501.15380 [pdf, ps, other]
arXiv:2607.02641 [pdf, ps, other]
arXiv:2607.03559 [pdf, ps, other]
arXiv:2607.03689 [pdf, ps, other]
arXiv:2603.10870 [pdf, ps, other]
arXiv:2607.02656 [pdf, ps, other]
arXiv:2607.02665 [pdf, ps, other]
arXiv:2607.03061 [pdf, ps, other]
arXiv:2607.03548 [pdf, ps, other]
arXiv:2605.07777 [pdf, ps, other]
arXiv:2607.03541 [pdf, ps, other]
arXiv:2607.04248 [pdf, ps, other]
arXiv:2607.04328 [pdf, ps, other]
arXiv:2606.05514 [pdf, ps, other]
arXiv:2606.28311 [pdf, ps, other]
arXiv:2607.02994 [pdf, ps, other]
arXiv:2607.03368 [pdf, ps, other]
arXiv:2607.03674 [pdf, ps, other]
arXiv:2607.03729 [pdf, ps, other]
arXiv:2512.10228 [pdf, ps, other]
arXiv:2512.18786 [pdf, ps, other]
arXiv:2607.02709 [pdf, ps, other]
arXiv:2607.03071 [pdf, ps, other]
arXiv:2607.03078 [pdf, ps, other]
arXiv:2607.03291 [pdf, ps, other]
arXiv:2607.03420 [pdf, ps, other]
arXiv:2607.03733 [pdf, ps, other]
arXiv:2607.03848 [pdf, ps, other]
arXiv:2607.04359 [pdf, ps, other]
arXiv:2510.25033 [pdf, ps, other]
arXiv:2603.17009 [pdf, ps, other]
arXiv:2603.21450 [pdf, ps, other]
arXiv:2604.18601 [pdf, ps, other]
arXiv:2606.01496 [pdf, ps, other]
arXiv:2607.02654 [pdf, ps, other]
arXiv:2607.02666 [pdf, ps, other]
arXiv:2607.02801 [pdf, ps, other]
arXiv:2607.03138 [pdf, ps, other]
arXiv:2607.03430 [pdf, ps, other]
arXiv:2607.03432 [pdf, ps, other]
arXiv:2607.04083 [pdf, ps, other]
arXiv:2607.04663 [pdf, ps, other]
arXiv:2607.04705 [pdf, ps, other]
arXiv:2607.04865 [pdf, ps, other]
arXiv:2506.14519 [pdf, ps, other]
arXiv:2511.04540 [pdf, ps, other]
arXiv:2511.11322 [pdf, ps, other]
arXiv:2512.00824 [pdf, ps, other]
arXiv:2601.15198 [pdf, ps, other]
arXiv:2601.17255 [pdf, ps, other]
arXiv:2602.04176 [pdf, ps, other]
arXiv:2602.12060 [pdf, ps, other]
arXiv:2602.21432 [pdf, ps, other]
arXiv:2603.06298 [pdf, ps, other]
arXiv:2603.16714 [pdf, ps, other]
arXiv:2604.00781 [pdf, ps, other]
arXiv:2604.07305 [pdf, ps, other]
arXiv:2604.11684 [pdf, ps, other]
arXiv:2605.12659 [pdf, ps, other]
arXiv:2606.04428 [pdf, ps, other]
arXiv:2606.26288 [pdf, ps, other]
arXiv:2607.01475 [pdf, ps, other]
arXiv:2607.02373 [pdf, ps, other]
arXiv:2607.02631 [pdf, ps, other]
arXiv:2607.02635 [pdf, ps, other]
arXiv:2607.02644 [pdf, ps, other]
arXiv:2607.02664 [pdf, ps, other]
arXiv:2607.02730 [pdf, ps, other]
arXiv:2607.02743 [pdf, ps, other]
arXiv:2607.02939 [pdf, ps, other]
arXiv:2607.03047 [pdf, ps, other]
arXiv:2607.03087 [pdf, ps, other]
arXiv:2607.03090 [pdf, ps, other]
arXiv:2607.03136 [pdf, ps, other]
arXiv:2607.03314 [pdf, ps, other]
arXiv:2607.03672 [pdf, ps, other]
arXiv:2607.03721 [pdf, ps, other]
arXiv:2607.03874 [pdf, ps, other]
arXiv:2607.03877 [pdf, ps, other]
arXiv:2607.03913 [pdf, ps, other]
arXiv:2607.04026 [pdf, ps, other]
arXiv:2607.04106 [pdf, ps, other]
arXiv:2607.04196 [pdf, ps, other]
arXiv:2607.04267 [pdf, ps, other]
arXiv:2607.04437 [pdf, ps, other]
arXiv:2607.04465 [pdf, ps, other]
arXiv:2607.04642 [pdf, ps, other]
arXiv:2607.04769 [pdf, ps, other]
arXiv:2607.04785 [pdf, ps, other]
arXiv:2607.04822 [pdf, ps, other]