Current date: 2026-09-01
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Datestamp limit: 2026-09-01 (0 days ago)
Created/updated limit: 2026-08-25 (7 days ago)
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Scoring abstracts
Number of records retrieved: 1252
Keyword score statistics
score 10 -- 1 abstracts
score 8 -- 1 abstracts
score 7 -- 2 abstracts
score 6 -- 1 abstracts
score 5 -- 3 abstracts
score 4 -- 8 abstracts
score 3 -- 10 abstracts
score 2 -- 39 abstracts
in total -- 65 abstracts
Articles that appeared on 2026-09-01
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[abstract 1 / 65] Wow! (score: 10)
- Title: From compact JETs to extended lobes: radio morphologies of distant QUASARs at z > 4Authors: K. É. Gabányi, M. Kunert-Bajraszewska, A. Krauze, S. Frey, M. Krezinger, Z. Paragi, H. Cao, T. An, L. I. Gurvits, K. Perger, T. Sbarrato, K. Rozgonyi,Comments: 17 pages, 11 figures, accepted for publication in Astronomy and Astrophysics, affiliation is correctedSubjects: astro-ph.GACreated: 2026-08-31; Updated: 2026-09-01; Datestamp: 2026-09-01
High-redshift QUASARs play an essential role in studying the growth and evolution of supermassive BLACK HOLEs and ACTIVE GALACTIC NUCLEi (AGN). Radio-loud QUASARs additionally enable us to investigate the interactions between the JETs and their environment. We aimed to reveal the radio morphology of three radio QUASARs at redshifts z>4 that contain milliarcsecond (mas) scale compact radio features according to previous very long baseline interferometry (VLBI) observations, but show significant flux density at arcsecond scales, indicating the presence of extended radio structure that cannot be sampled by the highest-resolution observations. We analysed radio interferometric data obtained at various angular resolutions and multiple frequencies, including observations made by the international Low-Frequency Array and the enhanced Multi-Element Remotely-Linked Interferometer Network. We also re-imaged archival European VLBI Network observations of our targets. Two QUASARs (J0813+3508 and J1231+3816) exhibit complex radio structures with hotspots, extended to tens of kpc. They resemble Fanaroff--Riley II-type RADIO GALAXies with extremely bent JET morphology. The third object (J1548+3335) shows a one-sided structure of $\lesssim 10$ kpc size. There was no sign of RELATIVISTIC boosting at its previous mas-scale resolution radio observations. Its radio power and (inferred) linear size derived from the lower-resolution observations are similar to the known high-power compact steep-spectrum sources. We found that the previously detected mas-scale compact radio features are related to the centres of the AGN or in one case to one of the hotspots in an extended lobe.
[abstract 2 / 65] Wow! (score: 8) - Title: ALMA Observations of DEM L241/LMC P3 in the Large Magellanic Cloud: Evidence for the Formation of Cool Molecular Jets Driven by a MicroQUASARAuthors: Yasuo Fukui, Bhuvana G. R., Hidetoshi Sano, Kisetsu Tsuge, Rami Z. E. Alsaberi, Rin Yamada, Yuya Asano, Aya Bamba, Miroslav Filipovic, Charles Law, Norikazu Mizuno, Toshikazu Onishi, Paul Plucinsky, Gavin Rowell, Manami Sasaki, Piyush Sharda, Hiromasa Suzuki, Kengo Tachihara, Kazuki Tokuda, Yumiko Yamane,Comments: Accepted for publication in ApJLSubjects: astro-ph.HE astro-ph.GACreated: 2026-08-31; Updated: 2026-09-01; Datestamp: 2026-09-01
We present ALMA observations of DEML 241/LMC P3, the most luminous $γ$-ray binary consisting of a compact object and an O star, in CO emission. We have found an one-sided JET-like CO feature of 8 pc length and 1 pc width, which accompanies another weaker CO JET candidate with slightly different orientation. The one-sided CO JET exhibits striking alignment with LMC P3, suggesting that the JET was driven by LMC P3. We have determined kinetic temperature of the CO JET to be significantly high at 33$-$60 K as compared with $\sim$15 K in the nearby non-JET CO cloud whereas no radiative heat source is found. We interpret that the high temperatures are due to shock heating of a microQUASAR JET driven by the $γ$-ray binary, where the compact object has an accretion disk fed by the O star winds. The CO JET matches existing predictions from MAGNETo-hydrodynamical simulations, which show that CO JET can form from the interaction of the microQUASAR JET and an ambient ISM cloud. These results provide strong evidence that CO JETs are a signature sculptured by microQUASAR JETs, lending support for mass accretion in LMC P3 as the $γ$-ray origin. The results suggest a second case of CO JETs potentially driven by a microQUASAR along with the CO JETs in the microQUASAR candidate HESS J1023-575 recently identified in the Milky Way. Further, our results suggest the use of sub-mm observations for identifying microQUASARs, opening a new possible window for their discovery and study.
[abstract 3 / 65] Wow! (score: 7) - Title: Constraining Cosmic-Ray Acceleration and Escape in Middle-Aged Supernova Remnants with GeV-TeV Gamma-Ray ObservationsAuthors: Siyu Chen, Bing Theodore Zhang, Yi Xing, Siming Liu, Xunxiu Zhou,Comments: 11 pages, 6 figuresSubjects: astro-ph.HECreated: 2026-08-30; Updated: 2026-09-01; Datestamp: 2026-09-01
In this work, we perform a systematic, time-dependent study of the gamma-ray emission from four representative middle-aged SNRs (W51C, IC~443, W44, W28), incorporating both CRs within the remnant shells and escaped CRs interacting with surrounding molecular clouds. We compare our results with GeV--TeV gamma-ray observations from FERMI-LAT, H.E.S.S., MAGIC, and LHAASO, including a dedicated analysis of the FERMI-LAT data for regions A and B associated with W28. We find that the observed spectra favor steeper CR injection spectra with indices of \(α\sim4.2\)--\(4.3\), maximum proton energies of $\sim$ \(100\)--\(300\) TeV, diffusion coefficients below the Galactic average, and CR acceleration efficiencies from a few to tens of percent. In particular, the VHE emission detected by LHAASO from W51C is more naturally explained by escaped CRs interacting with a nearby molecular cloud. We also investigate the contribution of escaped CRs to the VHE emission from IC~443, W44, and W28. We further demonstrate that escaped CRs can substantially enhance the TeV neutrino flux from middle-aged SNRs, improving their prospects as potential neutrino sources. These results provide new constraints on CR acceleration and escape in middle-aged SNRs and highlight the important role of escaped CRs in shaping their high-energy gamma-ray and neutrino emission.
[abstract 4 / 65] Wow! (score: 7) - Title: TeV Gamma Rays and Neutrinos from Winds Driven by Radiatively Inefficient Accretion Flows of Low-Luminosity Active Galactic NucleiAuthors: Nobuyuki Sakai, John F. Beacom, Kohta Murase,Comments: 15 pages, 5 figures, 1 tableSubjects: astro-ph.HE astro-ph.GACreated: 2026-08-31; Updated: 2026-09-01; Datestamp: 2026-09-01
Recently, the Large High Altitude Air Shower Observatory (LHAASO) reported the first TeV gamma-ray detection from a low-luminosity ACTIVE GALACTIC NUCLEus (LLAGN) lacking a strong JET. This source, NGC 4278, is one of the nearest LLAGNs that can be studied in detail as a template for more distant objects. Most previous studies have focused on the month-scale-variable gamma-ray activities, seeking to explain them with weak JETs. We focus instead on NGC 4278's quiet-period emission, proposing a different mechanism based on a wind launched from a radiatively inefficient accretion flow (RIAF). In particular, we model particle acceleration at a wind-driven shock and calculate the resulting multimessenger emission. To match the TeV gamma-ray fluxes reported by LHAASO in the quiet period, our model requires a wind power of $\lesssim2\times10^{43}~\mathrm{erg~s^{-1}}$ with a spectral index of injected COSMIC RAYs of 2.0. We show that this is achievable through Bondi accretion of the ionized gas observed on the 100-pc scale, for a shallow accretion profile. We discuss the testability of our wind-driven shock scenario with multimessenger observations. As another important application, we extend our model to Sgr A*, the nearest LLAGN, and show that its TeV gamma-ray emission is reproduced with reasonable parameters. Our results suggest that RIAF-driven winds may be a generic emission mechanism in LLAGNs, making this class a potentially important population of both gamma-ray emitters and cosmic-ray accelerators.
[abstract 5 / 65] Yes (score: 6) - Title: Hunting the nature of the Seyfert 1 galaxy GRS 1734-292: can it be a gamma-ray emitter?Authors: Luigi Foschini,Comments: 25 pages, 7 figures, 5 tablesSubjects: astro-ph.HE astro-ph.GACreated: 2026-08-31; Updated: 2026-09-01; Datestamp: 2026-09-01
It has been proposed that the radio-weak Seyfert galaxy GRS 1734-292 is the counterpart of 3EG J1736-2908 and of the nearby FERMI/LAT source. I examine this identification, considering that the radio weakness could result from free-free absorption of a RELATIVISTIC JET. An association with the EGRET detections is plausible, whereas the latest FERMI/LAT localization no longer favors GRS 1734-292. New observations, especially at radio frequencies of tens of GHz, would help to settle the issue.
[abstract 6 / 65] Yes (score: 5) - Title: Extension of a multi-region free-surface MHD solver beyond the inductionless approximationAuthors: Min Ki Jung, Brian Wynne, Francisco Saenz, Yufan Xu, Jabir Al-Salami, Yong-Su Na, Egemen Kolemen,Comments:Subjects: physics.comp-ph physics.plasm-phCreated: 2026-08-30; Updated: 2026-09-01; Datestamp: 2026-09-01
Free-surface liquid metal flows are a leading candidate for the plasma-facing components of future fusion reactors, but existing transient, three-dimensional, free-surface MHD solvers rely on the inductionless approximation, in which the induced MAGNETic field is neglected. This paper extends the open-source solver FreeMHD [B. Wynne et al., Phys. Plasmas 32, 013907 (2025)] beyond that approximation, resolving the induced field self-consistently with a vector-potential formulation that enforces $\nabla\cdot\boldsymbol{B}=0$ by construction while preserving the original multi-region, two-phase framework. It is verified against the analytical Shercliff and Hunt duct flows, against flows driven by a time-varying applied field, and against the deformation of a free liquid metal JET crossing a non-uniform field, and validated against free-surface height measurements from the LMX-U experiment. The experiment validates the overall free-surface solution rather than finite-$R_m$ effects, which the transient-field cases verify. To our knowledge this is the first open-source, fully three-dimensional free-surface liquid metal solver to resolve the evolution of the induced MAGNETic field, providing a basis for modeling the finite MAGNETic Reynolds number conditions expected in large-scale, transient fusion events.
[abstract 7 / 65] Yes (score: 5) - Title: Rapid Energy Dissipation by Colliding Waves in Strongly Magnetized PlasmasAuthors: Tianshu Wu, Xinyu Li, Yangyang Cai,Comments: 11 pages, 11 figuresSubjects: astro-ph.HE physics.plasm-phCreated: 2026-08-29; Updated: 2026-09-01; Datestamp: 2026-09-01
Rapid dissipation of MAGNETic energy in highly MAGNETized environments around neutron stars and BLACK HOLEs is a key open question in high-energy astrophysics. We develop a general kinetic picture of counter-propagating wave collisions in MAGNETized pair plasmas for arbitrary POLARIZATIONs and find that MAGNETic energy can be dissipated on the wave-crossing timescale. The two MAGNETohydrodynamical conditions on the field invariants, $I_1\equiv B^2-E^2>0$ and $I_2\equiv \mathbf{E}\cdot\mathbf{B}=0$, can be spontaneously violated during the collision. Parallel electric fields develop to screen nonzero $I_2$ with little energy loss, consistent with the evolution described by Force-Free Electrodynamics. When MAGNETic dominance is lost, strong particle energization is triggered, dissipating MAGNETic energy on the wave-crossing timescale. This dynamical process yields a rapid dissipation channel of MAGNETic energy and provides a kinetic pathway to high-energy emission.
[abstract 8 / 65] Yes (score: 5) - Title: The multi-frequency radio light curve of the sub-pc SMBH binary candidate PG 1302-102Authors: Sayan Basu, Roger P. Deane, Keith W. Bannister,Comments:Subjects: astro-ph.GA astro-ph.HECreated: 2026-08-30; Updated: 2026-09-01; Datestamp: 2026-09-01
Supermassive BLACK HOLE binary (SMBHB) candidates with sub-parsec (sub-pc) orbital separations are rare, high-value systems, thought to be the dominant sources of the recently detected nanoHertz (nHz) gravitational wave (GW) background. Alongside pulsar-timing-array searches for localized nHz GW sources from SMBHBs, an increasing number of candidates have been identified from synoptic surveys of large QUASAR optical light curves over increasingly long baselines. The optical light curve of the QUASAR PG~1302-102 at a redshift of $z=0.278$ exhibits a pronounced, smoothly varying periodic signal of ~5.2 years over approximately 20 years. Although the cause of this periodicity remains debated, a plausible explanation is a binary system of two SMBHs with a sub-pc separation. At this close distance, the $10^{8.3-9.4} M_{\odot}$ nuclear BLACK HOLEs in PG 1302-102 are expected to merge within $\sim$$10^{5}$ yr solely due to GW emission. We present a multi-frequency radio light curve analysis of PG~1302-102 spanning a $\sim$19-year baseline, with observations between 2005 and 2024 drawn from the Australian Telescope Compact Array (ATCA). The ATCA radio light curve is highly variable at 5.5~GHz but shows no significant evidence of the periodicity seen at optical wavelengths. However, we report fractionally stronger evidence of periodicity in the in-band spectral index time-series at 5.5~GHz, with a period consistent with the optical periodicity. Furthermore, the recently reported change in optical periodicity is also present in the radio in-band spectral index light curve. These two results suggest that radio and optical periodicity may be physically coupled despite very different emission mechanisms. We argue that this radio-optical coupling reinforces the SMBHB interpretation, despite the optical periodicity change, and provides an intriguing case study ahead of the LSST-SKAO era.
[abstract 9 / 65] Yes (score: 4) - Title: Simulation Study of Binary Mergers of Galaxy Clusters I: Properties of Merger Shocks and Radio EmissionAuthors: Hyesung Kang, Dongsu Ryu, Jeongbhin Seo,Comments: 36 pages, 18 figures, to appear in ApJSubjects: astro-ph.HECreated: 2026-08-29; Updated: 2026-09-01; Datestamp: 2026-09-01
We investigate binary mergers of galaxy clusters, the formation of shocks, and the resulting radio relics using three-dimensional simulations. The initial setup consists of two idealized spherical subclusters with a mass ratio below three, each permeated by turbulent MAGNETic fields, and we follow their merger with a high-order accurate MAGNETohydrodynamic (MHD) code. In parallel, we track the acceleration of cosmic-ray electrons (CRe) via diffusive shock acceleration (DSA) at merger-driven shocks, together with radiative cooling and FERMI-II (turbulent) acceleration in the postshock region, employing a newly developed Eulerian Fokker-Planck solver. Synchrotron emission is computed from the simulated CRe distribution and MAGNETic fields. In this paper, we detail these numerical approaches and present the first results obtained with them. Two prominent axial shocks emerge along the merger axis; the shock ahead of the heavier subcluster systematically attains a higher Mach number, although it is more compact, than that ahead of the lighter subcluster. Turbulent MAGNETic fields, which are both inherited from the initial conditions and amplified during the merger, produce patchy, fine-scale structures in the radio surface brightness. Because of the combined effects of turbulent acceleration, spatially nonuniform MAGNETic fields, and the curved geometry of merger shocks, the volume-integrated radio spectra show deviations from the canonical power-law steepening expected for a planar shock with a uniform field. Reacceleration of preexisting fossil CRe enhances the surface brightness. Our results highlight the coupled roles of merger dynamics, MHD turbulence, and CRe physics in shaping the observed properties of radio relics in cluster outskirts.
[abstract 10 / 65] Yes (score: 4) - Title: The GMRT High-Resolution Southern Sky Survey for pulsars and transients -- VIII: Orbital Variability and the Evolution of a 1-Day He-WD Millisecond Pulsar J2101-4802Authors: Ankita Ghosh, Bhaswati Bhattacharyya, David L. Kaplan, David A. Smith, Andrew Lyne, Jayanta Roy, Laila Vleeschower, Gabriella Agazie, Lankeswar Dey, Sangita Kumari, Ujjwal Panda,Comments: Accepted for publication in the ApJSubjects: astro-ph.HECreated: 2026-08-31; Updated: 2026-09-01; Datestamp: 2026-09-01
We present timing and orbital phase-resolved polarimetry of the millisecond pulsar (MSP) J2101$-$4802, having a spin period of 9.48~ms and dispersion measure (DM) $25.05\ \mathrm{pc\ cm^{-3}}$ discovered with the Giant Meter Radio Telescope (GMRT). From the phase-connected timing of this MSP spanning 3.7 years, we identify that PSR J2101-4802 is in a $\sim$1-day binary orbit with a likely helium-white-dwarf (He-WD) companion having a median companion mass of $\simeq0.15\, M_\odot$, consistent with canonical recycling in the Galactic field. The timing solution further reveals an unusually large orbital period derivative, $\dot{P}_b$ ($\sim10^{-11}\,{\rm s\,s}^{-1}$), compared to typical Galactic-field MSP--HeWD binaries, which cannot be explained by the contributions from kinematic effects (Shklovskii and Galactic acceleration) or general-RELATIVISTIC damping. Using wideband, full-Stokes observations, we also trace the linear and circular POLARIZATION variation across the orbital phase and fit a rotating-vector model (RVM) to its position-angle swing across the pulse phase, yielding constraints on the emission geometry (MAGNETic inclination and impact angle) of this system. The combination of a $\sim$1-day orbit, $\sim0.15\,M_\odot$ companion, modest spin-down power, unusually large $\dot{P}_b$, and phase-locked MAGNETized intrabinary plasma signatures suggests that PSR~J2101$-$4802 represents a transitional system linking redback-like spiders to detached He--WD MSP binaries.
[abstract 11 / 65] Yes (score: 4) - Title: Joint XMM-Newton and NUSTAR Observations of Type I X-ray Bursts from the Dipping Low-Mass X-ray Binary 4U 1323-62Authors: Tugba Boztepe, Tolga Guver, Ersin Gogus, Diego Altamirano, Julia Speicher, Brian Luff, David R. Ballantyne,Comments: Submitted to Monthly Notices of the Royal Astronomical SocietySubjects: astro-ph.HECreated: 2026-08-30; Updated: 2026-09-01; Datestamp: 2026-09-01
In this study, we report partly simultaneous XMM-Newton and NUSTAR observations of the bursting, dipping low mass X-ray binary, 4U 1323-62 obtained in 2024. 4U 1323-62 is one of the well-known persistent bursters, with bursts occurring roughly every three hours. It is also one of the few sources for which the orbital period is known, and shows dips in X-rays. In this paper, we report the detection of 12 unique bursts with XMM-Newton and NUSTAR, 6 of them observed jointly. We detected two double burst events, one with the NUSTAR and another one observed with both missions. During our observations we detected 10 X-ray dips with a periodicity of 2.942 hours, in line with previous measurements. We also present the results of the time resolved X-ray spectral analysis of the bursts and show the limits on the cooling of the corona heated by the burst emission. We also found a $0.898+/- 0.017 Hz quasi-periodic oscillation (QPO) during the non-bursting and non-dipping times confirming previous detections.
[abstract 12 / 65] Yes (score: 4) - Title: Constraints on the MAGNETic field in the hadronic scenario for the origin of the radio halo in the A1795 galaxy clusterAuthors: P. Marchegiani, V. Vacca, F. Loi, F. Govoni, M. Murgia,Comments: 5 pages, 1 appendix, 4 figures, 1 table; accepted for publication in A&ASubjects: astro-ph.HE astro-ph.COCreated: 2026-08-28; Updated: 2026-09-01; Datestamp: 2026-09-01
The radio halo in the cool-core galaxy cluster, A1795, has recently been proposed to be of hadronic origin, because it extends on megaparsec scales, where no turbulence is expected to be injected into a relaxed cluster. In this paper we aim to constrain the properties of nonthermal protons and the cluster MAGNETic field strength under the hypothesis of a hadronic origin for the radio halo in the light of the available gamma-ray upper limits for this cluster. We assumed a radial profile and several central MAGNETic field intensity values, then derived the corresponding properties of the nonthermal protons necessary to reproduce the flux density and surface brightness profile of the radio halo. For the obtained results, we calculated the corresponding gamma-ray emission and compared it with the FERMI-LAT upper limit. We find that, for a MAGNETic field energy radial profile following that of the thermal gas, central MAGNETic field intensities $B_0<5\,μ$G imply a gamma-ray emission at or above the FERMI-LAT upper limit. Therefore, larger values of the MAGNETic field are necessary in the hadronic scenario. For these values the radial profile of nonthermal protons must slightly decrease with radius, though more slowly than that of the thermal gas. For smaller values of the MAGNETic field, different mechanisms for producing or accelerating the nonthermal electrons are necessary.
[abstract 13 / 65] Yes (score: 4) - Title: Super-Eddington Little Blue Dots May Reionize Helium Too EarlyAuthors: Christopher Cain, Brent Smith, Gibson B. Bowling, Yongda Zhu, Lily Whitler, Rafael Ortiz, Anson D'Aloisio, Rogier Windhorst,Comments: 9+1 pages, 4+1 figures, submitted to ApJL. Comments welcomeSubjects: astro-ph.GA astro-ph.COCreated: 2026-08-28; Updated: 2026-09-01; Datestamp: 2026-09-01
The James Webb Space Telescope (JWST) has identified an abundant population of faint Active Galactic Nuclei (AGN) at $z \gtrsim 4$ which display broad emission lines, compact morphologies, and blue ultraviolet--optical continua. These ``Little Blue Dots' (LBDs) have been suggested to belong to the same family of objects as the more controversial ``Little Red Dots' (LRDs), with differences between the two largely owing to viewing angle effects. In this scenario, super-Eddington accretion resulting in high Extreme UV (EUV) and weak X-ray emission is invoked to explain the properties of both populations. We study the consequences of this super-Eddington scenario for the timing of Helium reionization. We find that observations which support an end to helium reionization no earlier than $z \approx 3$ disfavor scenarios in which the majority of observed $3 \lesssim z \lesssim 7$ LBDs are highly super-Eddington. For our fiducial super-Eddington accretion scenario, we find that the fraction of the LBD population in this state must be $\lesssim 10\%$, assuming LBDs make up $5\%$ of the $M_{ m UV} < -18$ galaxy population and have average escape fractions of $15\%$, comparable to recent observations. Our constraint assumes that LBDs dominate the Helium reionization budget, and would be tighter if bright QUASARs also contributed significantly. For a majority of LBDs to be super-Eddington, they would need to have small escape fractions ($\lesssim 1.5\%$) and/or be less abundant than observations suggest. Our conclusions are sensitive to the shape of the EUV spectra of super-Eddington BLACK HOLEs, motivating further study.
[abstract 14 / 65] Yes (score: 4) - Title: Decisive evidence for a global cosmic-ray feature in gamma-ray dataAuthors: Fernando Valenciano, Pedro De la Torre Luque, Daniele Gaggero, Jorge Martin Camalich,Comments: 5 pages, 2 figuresSubjects: astro-ph.HE astro-ph.GACreated: 2026-08-28; Updated: 2026-09-01; Datestamp: 2026-09-01
We analyze 17 years of FERMI-LAT data to study the diffuse $γ$-ray emission along the Galactic plane and its connection to cosmic-ray (CR) propagation. Accounting for correlated instrumental systematics, we find decisive evidence for a spectral break at $\sim20-30$ GeV, present across the inner Galactic disk, with a preference of $Δχ^2=39.78$ ($4.44 σ$ global). The energy and amplitude of this feature are in striking agreement with the spectral feature observed in local CR nuclei, indicating that it is a global property of the Galactic disk rather than a local phenomenon. The measured slope change, $Δγ\simeq 0.20$, is consistent with local CR data and with expectations from a transition in the CR diffusion regime from Kolmogorov to Kraichnan turbulence. Our results provide strong evidence that diffuse $γ$-ray emission along the Galactic disk is dominated by $π^0-$decay emission up to a hundred GeV. These findings provide key insights into the origin of the CR spectral hardening and the propagation of CRs throughout the Galaxy, and illustrate how this multimessenger approach can be used to probe the origin of features in the CR spectra, such as the long-studied CR Knee.
[abstract 15 / 65] Yes (score: 4) - Title: Radio-dust connection in QUASARs driven by powerful ionised outflowsAuthors: V. A. Fawcett, C. M. Harrison, T. Costa2, D. M. Alexander, C. Andonie, H. Haidar, R. D. Shepherd, C. L. Sargent, M. J. Temple, C. Circosta, D. J. Rosario,Comments: 17 pages, 16 figures, 1 table, accepted for publication in A&ASubjects: astro-ph.GACreated: 2026-08-28; Updated: 2026-09-01; Datestamp: 2026-09-01
Feedback from dusty QUASARs is thought to be a key driver in galaxy evolution. Multiple studies have reported a link between dust extinction and radio emission in QUASARs, possibly attributed to winds or JETs interacting with the interstellar medium. We use optical spectra from the Dark Energy Spectroscopic Instrument (DESI) to test whether ionised outflows could be driving the observed radio-dust connection and to determine whether dust and/or colour play a role in producing high-velocity ionised outflows in QUASARs. Based on a sample of 3418 DESI QUASARs at 0.5 < z < 0.9, we constrained the [OIII]$λ$5007 kinematics by fitting the spectra with PyQSOFit and comparing the observed trends among the [OIII] outflow velocity and the line-of-sight dust extinction E(B-V), optical-to-mid-infrared (MIR) colour g-W2, and L6$μ$m/L5100A (a proxy for MIR excess). Utilising radio data from the LOFAR Two-metre Sky Survey (LoTSS) DR2, we also explored the link between radio, dust, and outflows. We find that the link between radio emission and dust obscuration is driven by sources hosting high-velocity ionised outflows. However, we find no significant trend between the [OIII] outflow velocity and E(B-V), which suggests dust extinction alone is not a significant factor in determining whether a QUASAR hosts a powerful ionised outflow. On the other hand, we find a clear positive trend between g-W2 and outflow velocity, even after controlling for luminosity. We suggest this is due to a connection between a MIR excess (boosting the W2 band) and outflows, which is supported by a positive trend between L6$μ$m/L5100A and outflow velocity. Our results point to a scenario in which outflows shock the surrounding dust and gas, heating the dust and boosting both the MIR and radio emission.
[abstract 16 / 65] Yes (score: 4) - Title: Spheroidal Resampling Analysis of High-Redshift Gamma-Ray Burst Spatial DensitiesAuthors: Istvan Horvath, Zsolt Bagoly, Lajos G. Balazs, Jon Hakkila, Janos Horvath, Sandor Pinter, Istvan I. Racz, Peter Veres, Bendeguz Koncz,Comments: accepted for publicationSubjects: astro-ph.CO astro-ph.HECreated: 2026-08-30; Updated: 2026-09-01; Datestamp: 2026-09-01
Gamma-ray bursts (GRBs) are bright transient sources that can be observed at high redshift. They can therefore be used as tracers of the distant large-scale structure, although the GRB redshift sample is sparse and affected by strong selection effects. We analyze the three-dimensional distribution of 542 GRBs with spectroscopic redshifts. The method extends our earlier spherical-window search by replacing spherical counting volumes with axisymmetric spheroids. The angular positions of the observed GRBs are kept fixed in the Monte-Carlo null samples, while the redshifts are shuffled within each Galactic hemisphere. In the Northern Galactic hemisphere, the overdensity associated with the Hercules--Corona Borealis Great Wall remains significant for a range of spheroidal shapes. This supports the stability of the previously reported signal and shows that it is not only a consequence of using spherical counting volumes. In the Southern Galactic hemisphere, the same method finds no structure with comparable significance. A small candidate grouping is present, but its significance is only marginal, and it is sensitive to the small number of events. We conclude that spheroidal resampling is a useful check of GRB overdensity searches, but the physical nature of any candidate structure still requires confirmation with independent tracers such as galaxy or QUASAR samples.
[abstract 17 / 65] (score: 3) - Title: CANTON-$μ$ Proposal: A Next-Generation Muon $g-2$ Measurement at Sub-0.1 ppm PrecisionAuthors: Ce Zhang, Yu Xu, On Kim, Bingzhi Li, Zejia Lu, Saskia Charity, Guodong Shen, Liangwen Chen, Fedor Ignatov, Liang Li, Qiang Li, Xueheng Zhang, Zhiyu Sun,Comments: Revised manuscript submitted to EPJCSubjects: hep-ex hep-phCreated: 2026-08-31; Updated: 2026-09-01; Datestamp: 2026-09-01
We propose a next-generation precision measurement of the muon anomalous MAGNETic moment (muon g-2) at the High Intensity Heavy-Ion Accelerator Facility (HIAF) in Huizhou, China. We refer to this proposed experimental programme as CANTON-$μ$ (Coherent Anomalous magNetic momenT ObservatioN with muon). HIAF's intense, pulsed GeV-scale muon beams, particularly for negative muons, provide a promising basis for this programme. Building on two previously proposed storage-ring concepts, this work develops HIAF-specific experimental schemes that relax the conventional magic-momentum constraint and allow greater flexibility in the choice of beam momentum. We assess the expected muon intensity at HIAF and the corresponding statistical sensitivity. For each scheme, we identify its distinctive systematic effects, examine feasible control strategies, and propose quantitative systematic-uncertainty targets. Together, the statistical projections and systematic-uncertainty targets indicate prospective total precisions of 0.1 ppm in Phase-I, comparable to the current FERMIlab precision, with the potential to reach the 0.05 ppm level in in Phase-II following the planned HIAF upgrade. At the ultimate projected precision, the measurement would provide a stringent test of the Standard Model and probe new physics at multi-TeV scales. A focus on negative-muon measurements would enable direct comparison with existing high-precision positive-muon results and strengthen tests of CPT symmetry in the muon sector within the Standard-Model Extension, with a projected sensitivity at the $10^{-24}$ GeV level, an order of magnitude beyond current limits.
[abstract 18 / 65] (score: 3) - Title: Revisiting the Claim for a Direct-Collapse Black Hole in UHZ1 at $z=10.05$Authors: Fan Zou, Elena Gallo, Zihao Zuo, Edmund Hodges-Kluck, Dieu D. Nguyen, Guido Roberts-Borsani, Piero Madau, Fabio Pacucci, Anil C. Seth, Tommaso Treu, Shouyi Wang,Comments: 12 pages, 3 figures, 3 tables, accepted for publication in ApJSubjects: astro-ph.GA astro-ph.HECreated: 2026-08-31; Updated: 2026-09-01; Datestamp: 2026-09-01
We reassess the direct collapse BLACK HOLE (DCBH) interpretation of UHZ1 (UNCOVER-26185), a gravitationally lensed galaxy at $z_\mathrm{spec}=10.054$. That interpretation rests on a hard ($2-7$ keV) X-ray excess detected with Chandra, attributed to a Compton-thick AGN with an inferred $2-10$ keV luminosity of $L_\mathrm{X,int}\sim10^{46}~\mathrm{erg~s^{-1}}$ (Bogdan et al. 2024). The resulting extreme X-ray to rest-frame optical-IR ratio was taken as the hallmark signature of an "outsize BLACK HOLE galaxy" at cosmic dawn. We analyse the full 2.2 Ms Chandra imaging dataset -- including 0.95 Ms of unpublished observations -- and present new JWST/MIRI photometry at $λ_\mathrm{obs}>5~μ\mathrm{m}$. Across the full range of plausible Chandra data reductions, the $2-7$ keV excess at the position of UHZ1 reaches a significance of only $2.0-2.9σ$; the originally reported $4.2-4.4σ$ detection is sensitive to the specific astrometric alignment adopted and is not robustly reproducible. Moreover, the hard X-ray signal does not grow with the additional exposure, contrary to expectations for a steady source, indicating that any excess is not persistent. UHZ1 is also undetected in all nine MIRI imaging bands. Fitting red/obscured AGN SED templates to the tightest MIRI upper limit, we constrain the bolometric luminosity of any buried AGN to $L_\mathrm{bol}<1.3\times10^{45}~\mathrm{erg~s^{-1}}$. These conclusions are further supported by independent JWST spectroscopy (Alvarez-Marquez et al. 2026), which reveals no AGN signatures in the rest-frame UV or optical. Taken together, the multiwavelength data paint a consistent picture of UHZ1 as a low-mass, metal-poor, star-forming galaxy in the early Universe, with no compelling evidence for a luminous obscured AGN, regardless of its proposed formation channel.
[abstract 19 / 65] (score: 3) - Title: QPEs from Warped Disk Collisions with EMRIs: Brightness-Recurrence Diagram and Gravitational-Wave Follow-upAuthors: Bo-An Chen, Bei You, Giovanni Miniutti, Ning Jiang, Zhen Pan, Tao Yang, Xi-Long Fan, Kai Liao, Xu-Heng Ding, Zong-Hong Zhu, Shuai-Kang Yang, Sai-En Xu, Han He, Xiao Fan,Comments: 8 pages, 4 figures, submittedSubjects: astro-ph.HE astro-ph.CO astro-ph.GA gr-qcCreated: 2026-08-31; Updated: 2026-09-01; Datestamp: 2026-09-01
Quasi-Periodic Eruptions (QPEs) display correlated long/short and strong/weak patterns that remain unexplained by existing flat-disk collision models. We propose that these features arise from an extreme-mass-ratio inspiral (EMRI) colliding with a warped accretion disk, likely formed after a tidal disruption event. The warp modulates both recurrence time and burst energy, encoding the disk geometry -- and thus the spin of the central supermassive BLACK HOLE (SMBH) -- into the X-ray light curve. We introduce the Brightness-Recurrence Diagram (BRD) to visualize this correlation, where QPE bursts trace an elliptical trajectory driven by the EMRI's apsidal precession; the tilt of this ellipse encodes whether the EMRI is prograde or retrograde relative to the SMBH spin. Applying this model to the prototypical QPE source GSN 069 successfully reproduces the observed patterns. The data are consistent with either a prograde stellar secondary or a retrograde stellar-mass BLACK HOLE. In the stellar-mass BLACK HOLE scenario, ongoing orbital decay could render the EMRI detectable by LISA within a few decades, facilitating gravitational-wave follow-up and independent multimessenger constraints on the system.
[abstract 20 / 65] (score: 3) - Title: Fast radio bursts, MAGNETars and earthquakes: their "family feud"?Authors: Si-Lu Xu, Yong-Kun Zhang, Pei Wang, Di Li, Jun-Shuo Zhang, Tian-Cheng Lv, Yong-Feng Huang, Tian-Cong Wang, Long-Xuan Zhang, Pei-Xin Zhu, Jin-Huang Cao, Yi Feng, He Gao, Jian Li, Wan-Jin Lu, Chen-Chen Miao, Chen-Hui Niu, Qing-Yue Qu, Chao-Wei Tsai, Yi-Dan Wang, Wen-Ting Wang, Su-Ming Weng, Jia-Fu Wu, Ru-Shuang Zhao, Yuan-Chuan Zou, Yu-Hao Zhu, Ya-Biao Wang,Comments: 12 pages, 3 figures, accepted for publication in Science China Physics, Mechanics & AstronomySubjects: astro-ph.HECreated: 2026-08-30; Updated: 2026-09-01; Datestamp: 2026-09-01
Fast radio bursts (FRBs) are millisecond-duration cosmic transients whose origin remains elusive. Competing models invoke either earthquake-like processes or flare-like mechanisms. To discriminate between these scenarios, we develop a novel diagnostic, the Pincus-Lyapunov diagram (PLD), to characterize the energetic transients in the stochasticity-chaos phase space. We compile burst sequences from five representative FRBs (FRB 20121102A, FRB 20190520B, FRB 20201124A, FRB 20220912A, and FRB 20240114A), together with those from MAGNETar flares (SGR J1550$-$5418, SGR J0501+4516, SGR 1806$-$20, SGR 1900+14, and SGR J1935+2154), pulsar glitches, solar flares, and earthquakes, and map them onto the PLD for comparative analysis. The resulting diagram shows that FRBs occupy a distinct region of the phase space. Specifically, a permutation test reveals a statistically significant difference in the distributions of MAGNETar flares and pulsar glitches compared to those of repeating FRBs ($p$-value $\simeq 0.05$). To examine whether temporal variations in source activity can shift a repeater's position in this phase space, we analyze the time evolution of the most prolific repeater, FRB~20240114A. For this repeating FRB, both Pincus Index and Lyapunov Exponent demonstrate statistically stable behaviour over the eight-month observation session, with Augmented Dickey--Fuller tests yielding $p \simeq 1.78\times10^{-3}$ and $9.91\times10^{-3}$, respectively. By assembling the most comprehensive dataset to date, our work indicates that the trigger mechanisms of repeating FRBs are likely to be distinct from those driving MAGNETar flares, pulsar glitches, solar flares, and earthquakes.
[abstract 21 / 65] (score: 3) - Title: An SKA-Low RM Grid for constraining the origin of cosmic MAGNETismAuthors: Shane P. O'Sullivan, Franco Vazza, Ettore Carretti, Valentina Vacca, Francesca Loi,Comments: Published in Advancing Astrophysics with the SKA II (AASKAII), 2026 (arXiv:2606.20366). Report-no:AASKAII/OSullivan01Subjects: astro-ph.CO astro-ph.GACreated: 2026-08-30; Updated: 2026-09-01; Datestamp: 2026-09-01
Understanding the origin and evolution of cosmic MAGNETic fields is a key science goal for the SKAO. Recent advances in metre-wavelength (m-$λ$) Faraday rotation measure (RM) grids are enabling precision probes of cosmic MAGNETism, with implications extending to early-Universe physics, AGN feedback, and the MAGNETized circumgalactic medium. Here we model the m-$λ$ polarized source counts to predict an RM Grid density with SKA-Low of $N(>P) \sim 5 ({P}/{100{\rm μJy}})^{-0.75}\,\, {\rm deg}^{-2} $, where $P$ is the polarized intensity detection threshold. This represents at least an order of magnitude improvement over the current state-of-the-art. For a representative wide-area SKA-Low AA4 survey covering 10,000 deg$^2$ in $\sim$3,200 hours, we predict more than 50,000 RMs. Coupled with an expected RM precision of $\sim$0.05 rad/m$^2$, SKA-Low promises to produce the leading RM Grid survey for constraining the origin of cosmic MAGNETism in the SKA era. These predictions can be partially tested during the Science Verification phase using the AA* Sky Model data. For example, at a nominal detection threshold of 240~$μ$Jy/beam (8 times the noise in Stokes $Q$ and $U$), we expect $\sim$2.6 RMs/deg$^2$ (5x the current best m-$λ$ RM Grid density). Combining both wide-area and all-sky data, SKA-Low could detect up to 100,000 m-$λ$ RMs across its observable sky. Finally, we demonstrate new constraints on the origin of cosmic MAGNETism by comparing cosmological MHD simulations with the LOFAR m-$λ$ RMs, and highlight the transformative advances an SKA-Low RM Grid will enable for precision studies of cosmic MAGNETism.
[abstract 22 / 65] (score: 3) - Title: G(2) Glueball Boson Stars as Restricted Kerr Mimickers in the Thomas--FERMI LimitAuthors: Nicolò Masi,Comments:Subjects: astro-ph.HECreated: 2026-08-26; Updated: 2026-09-01; Datestamp: 2026-09-01
We investigate whether horizonless compact stars made of dark glueball matter from a broken exceptional $G(2)$ gauge sector can reproduce selected Kerr observables within a Thomas--FERMI effective-fluid description. We introduce GC9, a scale-separated $G(2)$-inspired positive nonic-density closure whose high-density stiffness, bag-free surface and Q-ball safety make it a useful compact-star benchmark. After Thomas--FERMI rescaling, reduced stellar observables are independent of the microscopic glueball mass $m_G$, while the collective stiffness $Λ_T$ fixes the dimensional mass and radius. Solving the TOV, Hinderer and Hartle--Thorne systems, we obtain a stable maximum-mass compactness $C=0.3247$, tidal deformability $Λ=4.37$, $\bar I C^{3/2}=0.947$, and slow-rotation quadrupole $\bar Q=1.522$. At $j=0.328$, the same-order ISCO shift is $1.24\%$. The stable endpoint has no light ring, but its exterior Regge--Wheeler barrier supports a genuine static axial mode, $Mω=0.463846-0.098881i$, with a damping time about ten percent shorter than Schwarzschild and a real frequency $24.1\%$ higher. A POLARIZATION-balanced vector realization has the same isotropic bulk EOS; moderate residual anisotropy changes static and first-order observables only at the few-percent level, while the full coupled vector spectrum remains open. Cowling calculations identify matter-supported quadrupolar modes. The scalar-burst, seeded-collapse and cosmological sections are phenomenological: a fixed $Λ_T$ gives a compact Kerr-comparison branch only near its own maximum mass, so the multi-sector scenario assumes distinct constant-$Λ_T$ branches from the keV supermassive sector to the PeV asteroid-mass sector. GC9 therefore defines a falsifiable restricted Kerr-mimicry framework for gravitational-wave, horizon-scale and compact-dark-matter tests.
[abstract 23 / 65] (score: 3) - Title: ELMO: An Uncertainty-Aware Simulation-to-Surrogate Workflow for Fast Pedestal Linear-Stability PredictionAuthors: Nami Li, X. Q. Xu, T. Osborne, E. Suchyta, Y. C. Fu, N. Podhorszki, H. Wang, Z. Li,Comments: 30 pages, 17 figuresSubjects: physics.plasm-phCreated: 2026-08-28; Updated: 2026-09-01; Datestamp: 2026-09-01
Rapid prediction of pedestal linear stability is important for exploring tokamak operating space, uncertainty quantification, and future model-informed control, but mode-resolved MAGNETohydrodynamic stability calculations using BOUT++ are computationally expensive. We present a focused implementation of ELMO--the Edge Learning and Modeling Orchestrator--as an uncertainty-aware simulation-to-surrogate workflow integrating equilibrium generation, field-aligned mesh construction, large-scale BOUT++ calculations, automated campaign execution and data reduction, and Gaussian Process Regression (GPR). For a single DIII-D plasma shape, 3,869 of 7,992 requested configurations completed equilibrium reconstruction, mesh generation, stability calculation, and quality control. Each retained equilibrium was evaluated at sixteen toroidal mode numbers, $n=5$--80 with $Δn=5$, using ideal-MHD and ideal-plus-diaMAGNETic models, producing 123,808 mode-resolved calculations. Using eight pedestal features, the GPR surrogate predicts two sixteen-mode growth-rate spectra with latent posterior uncertainty estimates. Across five independent test realizations, the maximum-growth-rate prediction achieved $R^2=0.978\pm0.013$ for ideal MHD and $R^2=0.966\pm0.009$ for ideal-plus-diaMAGNETic physics. The surrogate reproduces the spectral shape and dominant unstable mode. Calibration diagnostics indicate that posterior uncertainties are useful for relative acquisition but are underdispersed and should not be interpreted as calibrated prediction intervals. Prediction of all 32 outputs requires about 20 ms on one CPU core, compared with about 21 min using 128 CPU cores for the corresponding BOUT++ scan, giving a $6.3\times10^4$-fold wall-clock speedup and an $8.1\times10^6$-fold reduction in computational cost.
[abstract 24 / 65] (score: 3) - Title: Entropy-Stable and Physical-Constraint-Preserving DGSEM for Symmetry-Reduced General-Relativistic Hydrodynamics on Stationary SpacetimesAuthors: Guosheng Fu, Jian-Guo Liu,Comments: 63 pages, 8 figuresSubjects: math.NA cs.NA gr-qc physics.comp-phCreated: 2026-08-29; Updated: 2026-09-01; Datestamp: 2026-09-01
We develop an entropy-stable and physical-constraint-preserving discontinuous Galerkin spectral element method for symmetry-reduced general-RELATIVISTIC hydrodynamics on prescribed stationary spacetimes. Using a local orthonormal transformation, the fluid variables are expressed in a form for which the RELATIVISTIC hydrodynamic algebra and the admissible set are independent of the spatial metric, while the spacetime geometry enters through stationary coefficients. This separation allows entropy-conservative special-RELATIVISTIC fluxes to be combined with a compatible discretization of the geometric source terms. On affine tensor-product meshes, the resulting DGSEM is conservative and satisfies a semidiscrete entropy inequality, while the transformed variables provide a convex framework for physical-constraint preservation. For practical stabilization, we use a geometry-only causal speed that is sufficient for both classical local Lax--Friedrichs entropy dissipation and the physical-constraint-preserving Lax--Friedrichs splitting. The fully discrete method combines this stabilization with SSP Runge--Kutta time stepping, oscillation elimination, and conservative local-orthonormal-state scaling. Numerical experiments cover smooth and strongly shocked special-RELATIVISTIC flows, an axisymmetric JET, stationary Michel accretion, Schwarzschild Bondi--Hoyle flow, and four Kerr accretion cases. The results demonstrate the designed high-order accuracy in smooth regimes and robust performance for demanding RELATIVISTIC flows on curved stationary backgrounds.
[abstract 25 / 65] (score: 3) - Title: Type I Solar Radio Bursts Modulated by Solar FlaresAuthors: Yutong Li, Chuanyang Li, Yanke Tang, Ning Gai, Zichuan Li, Zhe Cui, Yang Gao, Yifan Wang, Xiaodong Xu, Xiaodi Huo,Comments:Subjects: astro-ph.SRCreated: 2026-08-30; Updated: 2026-09-01; Datestamp: 2026-09-01
Type I solar radio bursts (noise storms) are persistent meter-wave nonthermal emissions above active regions, with their occurrence and proper?ties closely related to the local MAGNETic configuration and nonthermal electron acceleration. This study examines a type I noise storm on 24 December 2023 and its relation to flare activity. The noise-storm source was co-spatial with active region AR 3529 and showed frequency-dependent spatial dispersion. The associated M2.9 flare strongly modulated the emission, with the storm intensity decreasing at flare onset, recovering afterward, and shifting to higher frequencies. Based on multiwavelength observations, we suggest that pre-flare small-scale RECONNECTion supplied nonthermal electrons to overlying closed MAGNETic struc?tures and maintained the storm. During the flare, MAGNETic RECONNECTion above the active region produced bidirectional plasma ejections and type III bursts with bidirectional frequency drifts; the gradually decreasing starting frequency of these bursts may indicate an upward-moving RECONNECTion site. The resulting MAGNETic reconfiguration disrupted electron trapping and suppressed the storm, whereas post-flare MAGNETic recovery allowed the emission to resume. These results show that flares can modulate type I noise storms through MAGNETic restructuring and provide insight into the generation mechanism of noise storms.
[abstract 26 / 65] (score: 3) - Title: STOKES tables and KY codesAuthors: Jakub Podgorný, Michal Dovčiak,Comments: Invited chapter for the edited book "X-ray Polarimetry: Detection, Observations, Modeling and the Future" (Eds. Honghui Liu and Adam Ingram), Springer Singapore, expected in 2026Subjects: astro-ph.HECreated: 2026-08-31; Updated: 2026-09-01; Datestamp: 2026-09-01
The family of KY codes is an XSPEC-compatible package of fully RELATIVISTIC models for spectro-polarimetric modeling of X-ray binary systems and ACTIVE GALACTIC NUCLEi. Within Kerr space-time, they compute accretion disc line profiles, reflection spectra from discs illuminated by Comptonized coronal radiation, and thermal disc emission including disc-corona interaction and disc self-irradiation. Many of these models include polarimetric computations, and more advanced timing variants compute X-ray, UV and optical reverberation. The primary source of Comptonized X-rays is assumed to be in the lamp-post on-axis or slab above the disc geometry. The KY codes operate at various levels of complexity; some models use analytical approximations for local re-processing, while others rely on detailed numerical tables. For the most accurate treatment of rest-frame re-processing in partially ionized accretion disc atmospheres, the KY codes employ pre-computed spectro-polarimetric tables generated with the STOKES code. These transmission and reflection tables are also designed for standalone use in XSPEC and as inputs to higher-level models beyond KY. The chapter first introduces the STOKES tables in various variants and shows their non-RELATIVISTIC usage in XSPEC models for (i) an extended source illuminating a distant geometrically thin disc, and (ii) a compact source illuminating a vertically extended equatorial obscurer (e.g., a torus or thick wind). The RELATIVISTIC KY ray-tracing is then described, followed by an introduction to each KY model. Examples of fits to the IXPE data of X-ray binaries and ACTIVE GALACTIC NUCLEi using these models are shown. Together, these models form a comprehensive and publicly available framework for spectro-polarimetric modeling and data fitting of accretion. We provide links to their online repositories.
[abstract 27 / 65] (score: 2) - Title: The Stochastic Siren: Astrophysical Gravitational-Wave Background Measurements of the Hubble ConstantAuthors: Bryce Cousins, Kristen Schumacher, Adrian Ka-Wai Chung, Colm Talbot, Thomas Callister, Daniel E. Holz, Nicolás Yunes,Comments: Version accepted by PRL. References updatedSubjects: astro-ph.CO gr-qcCreated: 2026-08-31; Updated: 2026-09-01; Datestamp: 2026-09-01
We report the first measurement of the Hubble constant $H_0$ using the stochastic gravitational-wave background arising from binary BLACK HOLE mergers. This astrophysical background is sensitive to the expansion history of the Universe and thus can be used for cosmological parameter inference independently of not only electroMAGNETic methods, but also gravitational-wave standard siren approaches. We describe the background's cosmological dependence and show how it can be used as a ``stochastic siren'' to measure $H_0$. By analyzing existing resolved binary BLACK HOLE mergers and the current non-detection of the background, we find that $H_0$ can be measured more accurately relative to using resolved mergers alone. We also note that the stochastic siren may serve a unique role in the Hubble tension in that the lower bound of the $H_0$ measurement would progressively increase with continued non-detection of the background.
[abstract 28 / 65] (score: 2) - Title: Examining the possibility of a thick crust in the compact stellar object HESS J1731-347Authors: Sebastian Kubis, Włodzimierz Wójcik,Comments: 8 pages, 5 figures, extended discussion of phase coexistence and EOS properties, the title changedSubjects: nucl-th astro-ph.HE astro-ph.SRCreated: 2026-08-31; Updated: 2026-09-01; Datestamp: 2026-09-01
A RELATIVISTIC mean-field model with a crossing term of isovector-scalar and isoscalar mesons, the Cracow crossing terms (CCT) model, has previously been shown to be capable of explaining the light and compact object HESS J1731-347 [11]. Here, the model is supplemented with a correct treatment of the phase transition. Applying the thermodynamically consistent Gibbs conditions shows that a mixed-phase system occurs in the core of the neutron star over a wide range of densities, extending up to the neutron star crust, leading to an intriguing stellar structure with a thick and massive crust.
[abstract 29 / 65] (score: 2) - Title: The Sagittarius C Complex in the Mid-Infrared with SOFIA/FORCASTAuthors: Roy J. Zhao, Mark R. Morris, Matthew J. Hankins, Angela S. Cotera, Janet P. Simpson,Comments: Revised version for ApJ submission. 24 pages, 11 figures. Comments welcome!Subjects: astro-ph.GACreated: 2026-08-31; Updated: 2026-09-01; Datestamp: 2026-09-01
We present an analysis of high-resolution mid-infrared observations at 25 and 37 $μm$ of the Sagittarius C Complex (Sgr C) in the Central Molecular Zone (CMZ), based on data from the SOFIA/FORCAST Galactic Center Legacy Survey. Enabled by the high bright-source limit of the FORCAST instrument, we perform a map-level dust temperature and optical depth analysis with a focus on the Sgr C HII region, which has an average dust temperature of 61 K and an average 37 $μm$ optical depth of 0.05. We find that the Sgr C HII region contains several high-density dust emission ridges, with lengths of up to several parsecs. Noting prior evidence for nonthermal radio emission from these density ridges, we postulate that there is an enhancement of RELATIVISTIC electrons within them, possibly attributable to diffusive shock acceleration induced by the wind of a known nearby Wolf-Rayet (WR) star impacting the density ridges and the ambient gas in the surrounding photo-dissociation region. Additionally, the tangential MAGNETic field in the outskirts of the Sgr C HII region may serve to confine the electrons within this region. We examined the heating effect of the WR star by calculating its heating profile and performing a spectral energy distribution modelling of the HII region. We found an integrated MIR luminosity of $(1.40\pm0.19)\times10^{6} L_\odot$, which implies that presently unidentified massive stars must be present in the HII region in addition to the WR star. We also present a brief analysis of adjacent regions, such as a mid-infrared/radio source denoted "Source C" and the G359.43+0.02 young stellar object cluster near the northern end of the prominent Sgr C non-thermal filament (NTF).
[abstract 30 / 65] (score: 2) - Title: $D$-dimensional aether charged BLACK HOLE and aether waves in M-subclass of Einstein-aether theoryAuthors: Chikun Ding, Yuebing Zhou, Yu Shi, Xiangyun Fu,Comments: 18 pages, 2 figure, accepted by Comm. Theor. PhysSubjects: gr-qc hep-thCreated: 2026-08-29; Updated: 2026-09-01; Datestamp: 2026-09-01
We obtain an exact $D$-dimensional aether charged BLACK HOLE solution and gravitational wave POLARIZATIONs in the M-subclass of the Einstein-aether theory with Lorentz invariance violated by an unit norm vector field---the aether field $u^μ$. This aether field can be timelike or spacelike and, the aether charge $Q_æ$ has a nonzero minimum value, which is different from the electric charge. The aether electric-like potential $u_t$ is regular, and the aether MAGNETic-like potential $u_r$ is singular at the horizons. Though the Lorentz symmetry is broken, the Smarr formula and the first law of BLACK HOLE thermodynamics can be exactly constructed via the extended method of Killing potential. However, we find this conception of the aether charge doesn't exist in the $c_i$ subclass of the Einstein-aether theory. For the linearized M-subclass Einstein-aether theory with the timelike aether field, we find the speed of spin-2 modes (the usual gravitational wave) is still equal to 1. But there is only one POLARIZATION $γ_{12}$ that can propagate, while the other one, $γ_{11}$ cannot propagate for $D=4$ due to the effect of Lorentz symmetry breaking. The speed of spin-1 modes (the transverse aether wave) is also equal to 1. The third kind mode is the longitudinal aether-metric mode, which is linearly time dependent and not the spin-0 mode reported in the $c_i$ subclass Einstein-aether theory.
[abstract 31 / 65] (score: 2) - Title: Spin Light of neutrino in polarized matterAuthors: Alexander Grigoriev, Alexei Ternov,Comments: 13 pages, 1 figure. Accepted for publication in Chinese Physics CSubjects: hep-ph astro-ph.HECreated: 2026-08-29; Updated: 2026-09-01; Datestamp: 2026-09-01
The Spin Light of neutrino ($SLν$) is an electroMAGNETic radiation of the neutrino MAGNETic moment emitted when neutrino moves in external conditions (fields or matter). The effect can be of significance in the extremely dense matter of compact astrophysical objects such as neutron stars (NS). If detected, this radiation could provide a fair opportunity to study the properties of neutrinos and the medium through which they move, since the properties of the radiation depend on both. Motivated by the possibility of the nuclear matter spin-POLARIZATION, in this paper, we study the new properties to $SLν$ obtained under the influence of net matter POLARIZATION. We demonstrate that the POLARIZATION can enhance or completely suppress the radiation. Also, it introduces a characteristic asymmetry into the total radiation from the compact object, which could be an observable feature dependent on the matter POLARIZATION and the MAGNETic field inside the stellar (if the field is connected to the stellar matter POLARIZATION). The research may have implications for the physics of NS and MAGNETars, bringing us closer to the possibility of studying their internal structure.
[abstract 32 / 65] (score: 2) - Title: Collisionless relaxation as the origin of the anisotropic, non-thermal, and multi-temperature momentum distributions observed in space plasmasAuthors: Torsten Enßlin, Christoph Pfrommer,Comments: 19 pages, 1 figureSubjects: physics.plasm-ph astro-ph.HECreated: 2026-08-31; Updated: 2026-09-01; Datestamp: 2026-09-01
Anisotropic, non-thermal, and multi-temperature distributed particle momenta are commonly observed in collisionless space plasmas, such as the solar wind. Using Liouville's theorem, we argue that anisotropic compression or expansion of the plasma, followed by a relaxation of the resulting anisotropic stress must lead to non-equilibrium states that exhibit either anisotropic, non-thermal distribution functions, different electron and ion temperatures, or a combination of these effects. We present arguments showing that a plasma in thermal equilibrium undergoing anisotropic compression or expansion cannot return to thermal equilibrium in the absence of particle collisions. Since most astrophysical plasmas are practically collisionless and experience significant anisotropic compression or expansion, we expect anisotropic, non-thermal, and multi-temperature particle distributions to be ubiquitous, in agreement with solar wind measurements.
[abstract 33 / 65] (score: 2) - Title: Constraining Axion-like Particles through Multi-epoch Monitoring of Strong Gravitational LensesAuthors: Shivani Deshmukh, Aritra Basu, Dominik J. Schwarz, Yuko Urakawa, Sui Ann Mao,Comments: 29 pages, 10 figures. Accepted for publication in JCAPSubjects: astro-ph.COCreated: 2026-08-30; Updated: 2026-09-01; Datestamp: 2026-09-01
We present new constraints on ultralight axion-like particles (ALPs) through multi-epoch measurements of differential birefringence induced due to a coupling ($g_{aγ}$) between the ALP and electroMAGNETic fields. Broadband polarimetric observations in the 2-8 GHz range of the gravitationally lensed system CLASS B1152+199 were carried out over five epochs spanning three months with a cadence of roughly 20 days, and the differential birefringence angle ($Δ\,θ_{a,{\rm lens}}$) between the lensed images were estimated. We also combined an archival observation that effectively increases the span to 9.5 yr to probe the effect of an oscillating ALP field imprinted as oscillating $Δ\,θ_{a,{\rm lens}}$ over time. Here we present a new technique for combining multi-epoch measurements of $Δ\,θ_{a,{\rm lens}}$ by considering the coherence of the ALP field, such that, $Δ\,θ_{a,{\rm lens}}$ over these observations are related. The time scale of coherence depends on the mass of the ALP field ($m_a$). Our results are consistent with non-detection and we constrain $g_{aγ} \leq 7.8\times 10^{-12} \,\left( {ρ_{a,\text{em}}}/{20 \text{ GeV cm}^{-3}} \right)^{-1/2}\;\mathrm{GeV}^{-1}$ to $\leq 3.2\times 10^{-8} \,\left( {ρ_{a,\text{em}}}/{20 \text{ GeV cm}^{-3}} \right)^{-1/2}\;\mathrm{GeV}^{-1}$ at 95% confidence for $m_a$ between $1.6\times 10^{-22}\;\mathrm{eV}$ and $3.8\times 10^{-18}\;\mathrm{eV}$, where $ρ_{a,{\rm em}}$ is the density of the ALP field at emission. This improves over the constraint provided by the CERN Axion Solar Telescope by up to an order of magnitude in the $m_a$ range $1.6\times 10^{-22}\;\mathrm{eV}$ to $3\times 10^{-21}$ eV.
[abstract 34 / 65] (score: 2) - Title: From NVSS to RACS: Identifying truly Compact Galactic and Extragalactic sources with Steep SpectraAuthors: Rajat Shinde, Yogesh Maan, Apurba Bera,Comments: 16 pages, 6 figures, accepted for publication in PASASubjects: astro-ph.GA astro-ph.HECreated: 2026-08-31; Updated: 2026-09-01; Datestamp: 2026-09-01
Compact, steep-spectrum radio sources are key tracers of exotic astrophysical objects such as pulsars and high-redshift RADIO GALAXies. All-sky radio surveys at different frequencies, like the TIFR-GMRT Sky Survey (TGSS) and the NRAO VLA Sky Survey (NVSS), have been usually exploited to identify such tracers. The more recent imaging survey, Rapid ASKAP Continuum Survey (RACS), with higher angular resolution and better sensitivity offers an avenue for a far better identification and characterisation of compact, steep-spectrum sources. In this work, using publicly available RACS images at 887 MHz and 1.4 GHz, we present an image-domain characterisation of 171 compact source candidates between declinations -40 degrees and +41 degrees, that were detected and appeared compact at 147 MHz in TGSS but not detected at 1.4 GHz in NVSS. Our detailed characterisation resulted in the identification of 66 compact sources, 87 non-compact, diffuse or resolved sources, and 18 sources that are not detected in either of the RACS or NVSS images, implying spectral indices steeper than -2.0. Out of the 66 compact sources, 38 have spectral indices steeper than -1.5. We demonstrate that a large fraction of the sources in our sample were earlier not detected and resulted in incorrect spectral index limits due to poor imaging quality of NVSS in the Galactic plane. We present the spectral indices and morphological classification of all the sources in our sample and discuss their usefulness in identifying and studying interesting sources such as radio pulsars, high-redshift RADIO GALAXies, and other extragalactic sources.
[abstract 35 / 65] (score: 2) - Title: Remarks on electrical Penrose process for MAGNETized Reissner-Nordström BLACK HOLEAuthors: A. Baez, Nora Breton, I. Cabrera-Munguia,Comments: 19 pages, 16 figures, published version in PRDSubjects: gr-qcCreated: 2026-08-28; Updated: 2026-09-01; Datestamp: 2026-09-01
The energy extraction from a MAGNETized Reissner-Nordström BLACK HOLE is analyzed within the framework of the electric Penrose mechanism. The presence of an external MAGNETic field induces an axisymmetric configuration and an ergosphere (the region where energy extraction is possible) arises, allowing for negative energy states even in an otherwise static spacetime. By analyzing the decay of particles at turning points of the radial motion, we derive the general expression for the efficiency of the process in terms of the metric coefficients and the electroMAGNETic potential. The resulting efficiencies are interpreted as Killing energy efficiencies associated with the local splitting process, while the escape of the positive energy fragment is treated as an additional effective-potential requirement. This formulation provides a direct criterion for identifying the ergoregions and we show that the MAGNETic field acts as a control parameter that governs both the configuration of the ergosphere and the efficiency of the process. In particular, analytical expressions for the critical MAGNETic fields that determine the onset and suppression of energy extraction are determined. Our results extend previous analysis of the electric Penrose process for MAGNETized configurations and clarify the role of the external field in enhancing or inhibiting energy extraction from charged BLACK HOLEs.
[abstract 36 / 65] (score: 2) - Title: The Chirp-Mass Ladder: A New Rung EmergesAuthors: Vaibhav Tiwari,Comments:Subjects: astro-ph.HECreated: 2026-08-31; Updated: 2026-09-01; Datestamp: 2026-09-01
The population of binary BLACK HOLEs (BBHs) observed through gravitational waves (GWs) now includes 256 events with the release of GWTC-5.0, enabling more detailed studies. The inferred chirp-mass distribution shows prominent peaks at approximately $7.5M_{\odot}$, $14M_{\odot}$, and $27M_{\odot}$, with subsequent peaks spaced by approximately a factor of two. A parsimonious explanation for this structured distribution is a hierarchical merger scenario, in which the first peak arises from mergers of BLACK HOLEs of stellar origin, and higher-mass peaks arise from repeated mergers. Notably, with the addition of new observations, an intermediate peak near $19M_{\odot}$ emerges. This feature was anticipated in earlier work as a consequence of intergenerational mergers involving second- and third-generation (G) BLACK HOLEs, highlighting the predictive expectations of the hierarchical-merger interpretation. Furthermore, two groups of $1G+2G$ mergers recently reported in separate studies can be understood as distinct rungs---$1G+2G$ and $3G+4G$---within this hierarchical chirp-mass ladder, a unification that describes both spin transitions with a single mechanism. Although we observe expected correlations between mass ratios and spins in multiple events across the mass range, the lack of clear signatures across all rungs invites investigation into the role of hierarchical mergers in shaping the BBH population.
[abstract 37 / 65] (score: 2) - Title: Multi-branch classification of diffuse cluster radio emission from the LOFAR two-metre sky surveyAuthors: Markus Bredberg, Emma Tolley,Comments: 17 pages, 12 figures, Accepted in A&ASubjects: astro-ph.COCreated: 2026-08-31; Updated: 2026-09-01; Datestamp: 2026-09-01
Context. Galaxy clusters sometimes host SYNCHROTRON radiation on scales of approximately 100 kpc to approximately 1 Mpc, with a surface brightness only a few times the image noise. This diffuse cluster radio emission is a sensitive probe of MAGNETic fields and intracluster medium dynamics, but disentangling the underlying physical processes requires statistically large samples spanning a wide range of cluster masses, dynamical states, and redshifts, together with a sufficient sensitivity to low-surface-brightness emission. Aims. We explore two techniques for improving the detection of diffuse emission in galaxy cluster images, relative to a baseline classifier: the scattering transform (ST) and squeeze-excitation (SE) attention. Methods. We integrated an ST encoder into a dual-branch classifier (DualSSN) and a scattering network (ScatterNet). We incorporated SE attention into the DualSSN and dual-branch convolutional neural network (DualCSN). These classifiers were then benchmarked against a simple convolutional neural network (CNN), across ten image pre-processing configurations and three cropping strategies. Performance was evaluated on small labelled datasets from the second data release of the LOFAR Two-metre Sky Survey overlapping with the Second Planck catalogue of Sunyaev-Zel'dovich sources (LoTSS-DR2/PSZ2). Results. Alongside the multi-branch approach with SE and ST, cropping the image to a fixed number of telescope beams and uv tapering (smoothing to a coarser angular resolution) improve classification performance, while tacking multiple pre-processed versions of an image does not. Conclusions. Scattering-transform-based multi-branch architectures with beam-normalised cropping are a promising direction for diffuse emission classification in the SKA era.
[abstract 38 / 65] (score: 2) - Title: A unified gas-kinetic wave-particle method for multiscale gas-mixture flow with an elementary chemical reactionAuthors: Junzhe Cao, Yufeng Wei, Wenpei Long, Chengwen Zhong, Kun Xu,Comments:Subjects: physics.comp-ph physics.flu-dynCreated: 2026-08-31; Updated: 2026-09-01; Datestamp: 2026-09-01
Hypersonic flows in the near space often couple continuum-rarefied multiscale effect with finite-rate chemistry. This paper extends the UGKWP method to multiscale gas mixture flows with a single elementary reaction. In the UGKWP method, hydrodynamic waves are employed to describe near-equilibrium distribution functions, and numerical particles are used for the evolution of nonequilibrium ones. The adaptive conversion between waves and particles, guided by the characteristic integral solution, together with the introduction of dt into the flux as an observation scale, has enabled the UGKWP method to succeed in many multiscale problems involving complex physics. In this work, rather than relying on a comprehensive reactive kinetic model for the entire distribution function, chemical source terms are first evaluated at the macroscopic level and then incorporated into the wave-particle update, while free-transport particles are kept chemically inactive in the monatomic setting considered here. This approach leverages the modeling advantages of wave-particle decoupling, facilitating extension to more complex chemical reactions. Moreover, an approximate extension of an advanced multispecies kinetic model is developed in this work for multispecies effect with species number larger than two. The present UGKWP method is assessed for the Zeldovich-type reaction O2+N=NO+O through hypersonic cylinder flows over a wide Knudsen number range, covering chemically inert, forward exothermic, forward endothermic and dE=0 conditions, and through shock structures with hot upstream/downstream equilibrium states. Agreement with DSMC is obtained for gas mixture flow fields, species mole fractions and wall quantities. A three-dimensional side JET flow over a blunt cone is further simulated to demonstrate the three-dimensional capability of the present code.
[abstract 39 / 65] (score: 2) - Title: Galactic Science with Ultra-High Angular Resolution X-ray ImagingAuthors: Paul A. Draghis, Jeremy Hare, Mayura Balakrishnan, Poshak Gandhi, Tyler Holland-Ashford, Margarita Karovska, Thomas Maccarone, Herman L. Marshall, Mark Reynolds, Malgosia Sobolewska, Ryan Tanner,Comments: This is a report generated in response to a call by the X-ray Science Interest Group of the NASA Physics of the Cosmos Program Analysis Group (PhysPAG). A summary of all five reports can be found at https://doi.org/10.48550/arXiv.2606.28138Subjects: astro-ph.HE astro-ph.IMCreated: 2026-08-28; Updated: 2026-09-01; Datestamp: 2026-09-01
Milli- to micro-arcsecond X-ray imaging will open a new observational regime for Galactic astrophysics by resolving physical scales that are inaccessible to current X-ray observatories. This white paper highlights the science enabled by such capabilities across four broad questions: how particles are accelerated, how stars die, how accretion is fueled, and what populations of X-ray sources inhabit the Galaxy. Ultra-high angular resolution will enable many new studies, such as resolving shocks and JETs, measuring proper motions, parallaxes, and binary orbits, and providing secure multiwavelength counterpart identifications in crowded environments such as the Galactic Center and globular clusters. Combined with high-time-resolution observations, these measurements will connect variability and transient events to the physical structures in which they originate, while coordination with gravitational-wave, neutrino, $γ$-ray, radio, optical, and infrared facilities will provide spatial information needed to identify and characterize multi-messenger sources. In addition to defining the science cases, this paper presents a curated list of compelling targets spanning various angular resolutions and outlines the complementary specifications necessary to maximize the scientific outcome. Accomplishing these science goals will require an instrument with high angular resolution, precise astrometry, substantial collecting area, sufficient spectral and timing resolution, and high dynamic range imaging capabilities.
[abstract 40 / 65] (score: 2) - Title: Droplet sizes from impulsive capillary JETs: an exponential distribution with no lower cut-offAuthors: Alfonso M. Ganan-Calvo,Comments: 8 pages, 4 figuresSubjects: physics.flu-dynCreated: 2026-08-28; Updated: 2026-09-01; Datestamp: 2026-09-01
A collapsing cavity throws up a ligament, which fragments into a train of droplets whose sizes are commonly given a lower bound at a fixed multiple of the viscocapillary length $\ell_μ=μ^2/ρσ$. We show that no such bound exists, for a reason more general than the fate of one parameter: an impulsive JET possesses no length of its own. The similarity solutions that govern each pinch contain none, the cascade of stretching and iterated satellites introduces none, and $\ell_μ$ belongs to the singularity rather than to the droplets. A size distribution built on such a process can inherit a scale from one place only, the cavity that launched the JET. Computations of bubble bursting, confined and unconfined, bear this out. The floor they display is the one the mesh imposes, not a property of the fluid, and wherever the mesh looks below $\ell_μ$ it finds droplets. The census of unique emitted droplets is exponential, with a single scale set by the cavity radius, indifferent both to how vigorous the event is and to how much liquid surrounds it. An exponential is the least structured census compatible with a prescribed mean, so the fragmentation keeps the size of the cavity and no other memory of its parent. Sustained stretching does keep such a memory, imprinting the corrugation of the parent thread and yielding the peaked, gamma-like distributions reported for ligament-mediated fragmentation. The manner of loading, and not the fluid alone, selects the shape of a spray.
[abstract 41 / 65] (score: 2) - Title: Statistical Energy Budget of the Solar Wind with Parker Solar Probe and Solar Orbiter : 1 - Unbalanced Total Energy Radial EvolutionAuthors: Jean-Baptiste Dakeyo, Pascal Démoulin, Victor Réville, Stuart Bale, Tamar Ervin, Milan Maksimovic, Olga Alexandrova, Mingzhe Liu, Roberto Livi, Nikos Sioulas, Orlando Romeo, Alexis Rouillard,Comments: 24 pages, 10 figures, 1 tableSubjects: astro-ph.SRCreated: 2026-08-28; Updated: 2026-09-01; Datestamp: 2026-09-01
The MAGNETo-hydrodynamic (MHD) description of the solar wind has long been regarded as one of the most successful frameworks for investigating solar wind heating and acceleration. Under a set of simplifying assumptions, it provides a reduced large-scale description that is widely used to study the energetic role of electroMAGNETic fluctuations in the solar wind energy budget. In practice, applying simplification to MHD can result in the loss of some physics compared to an exact set of equations. However, an observational energy budget can help us to verify whether any energetic information has been lost in the process of simplification. To do so, we directly test the validity of the large-scale non-linear ideal MHD energy budget with solar wind observations from Parker Solar Probe (PSP) and Solar Orbiter (SO). After verifying the reliability of the measurements through comparison with previous studies of similar solar wind properties, we test the conservation of the total energy predicted by the MHD theory. We find that the average total energy increases with radial distance by $56\%$ ($\pm9\%$) between 14 and 203 solar radii. The increase in kinetic energy is not sufficiently compensated by the decrease of the thermal and electroMAGNETic contributions. We investigate the major sources of observational uncertainty and find that they cannot account for the observed energy increase. These results suggest that the large-scale theoretical description may neglect an energetically significant contribution to solar wind acceleration. Assuming that such a contribution exists, we predict that this extra energy would scale with radial distance as $r^{-0.54\pm0.38}$.
[abstract 42 / 65] (score: 2) - Title: A Self-Sustaining Black Hole Engine Powered by the Tidal Disruptions of StarsAuthors: James Guillochon, Avi Loeb,Comments: 28 pages, 4 figures. Submitted to the Open Journal of AstrophysicsSubjects: astro-ph.HE astro-ph.GACreated: 2026-08-28; Updated: 2026-09-01; Datestamp: 2026-09-01
Tidal disruption events (TDEs) strongly prefer host galaxies undergoing, or recovering from, a burst of STAR FORMATION, implying that a rare minority of galaxy types produces most events. The required per-galaxy rates, as high as $10^{-2}$ gal$^{-1}$ yr$^{-1}$, are hard to achieve through stellar relaxation alone. Molecular clouds surrounding nuclear clusters help set the relaxation rate, offering a path to higher rates. We show that (post-)starburst galaxies, whose nearby prototypes contain large molecular gas reservoirs, are likely in a self-sustaining cycle: an enhanced disruption rate compresses the surrounding clouds through momentum injected by the unbound debris, the denser clouds compress the cluster, and the cluster disrupts stars faster still. The runaway is arrested only when stars begin to collide. Solving for the steady state, the rate saturates at $1.4\times10^{-2}(M_{\rm h}/10^{6}M_\odot)^{-0.84}$ yr$^{-1}$, two orders of magnitude above the canonical rate at $10^{6}M_\odot$, with a normalization uncertain by a further two orders of magnitude through the stellar collision rate. Three independent requirements --- that tidal debris outweigh AGN feedback, that the molecular clouds fit within the disk that holds them, and that the cusp be no denser than observed nuclei --- bound the flattening of the stellar cusp to $0.18 \lesssim f_\ast \lesssim 0.25$. Because no engine can run below a threshold BLACK HOLE mass, holes seeded beneath it stay dark until accretion carries them across, switching on after $\sim 1$ Gyr and offering a natural explanation for the late peak recently measured in the TDE delay time distribution. The nucleus is buried under $A_V \simeq 50$ whatever its geometry, so most such disruptions should be hidden from optical surveys and emerge instead in the infrared.
[abstract 43 / 65] (score: 2) - Title: Anomalous horizontal track-like events at the HAWC observatory: candidate neutrino-induced charged leptons from the Pico de Orizaba volcanoAuthors: Hermes León Vargas, Andrés Sandoval,Comments:Subjects: astro-ph.HE hep-ex hep-phCreated: 2026-08-28; Updated: 2026-09-01; Datestamp: 2026-09-01
Two track-like events with exceptionally large charge deposits, pointing back to the region of maximum overburden ($>18$ km.w.e.) of the Pico de Orizaba volcano, were reported by the HAWC Collaboration in a search for Earth-skimming neutrinos. Using exclusively published information, including the published Monte Carlo charge distributions and the scattered-muon background model, we show that these events are kinematically inconsistent with all identified backgrounds. A conservative energy-conservation bound places the in-tank energy deposit of the candidates above $\approx$190--210~GeV, with a worst-case minimum of 122--136~GeV, in either case exceeding the 100~GeV maximum of the scattered-muon background model. Calibration systematics derived from the published simulations act unidirectionally, pushing the implied deposits into the multi-TeV regime. Direct atmospheric muons require $E_μ\gtrsim 0.67$~PeV to penetrate the overburden and contribute $4.5\times10^{-5}$ expected events ($\lesssim 10^{-3}$ under the largest possible prompt-charm flux); collinear muon bundles are excluded by five independent arguments. Conversely, the neutrino hypothesis predicts identifiable events precisely in the observed charge window ($10^{3}$--$10^{4}$ photoelectrons) and in the highest-overburden analysis region, both observed. The two track-like events imply a rate that exceeds the conventional atmospheric neutrino flux expectation at the 2.1--2.5$σ$ level. The charges of the observed candidates require an emerging lepton above about 20~TeV; the published calibration does not bound the energy from above. These would constitute the first neutrino candidates detected in Mexico and the first obtained with the Earth-skimming volcano technique.
[abstract 44 / 65] (score: 2) - Title: Evidence for an accretion-driven subpopulation of BLACK HOLEs in GWTC-5.0Authors: Zacharias Roupas,Comments:Subjects: astro-ph.HE astro-ph.GACreated: 2026-08-29; Updated: 2026-09-01; Datestamp: 2026-09-01
We report Bayesian evidence for a subpopulation of BLACK HOLEs, grown via accretion during the gaseous birth-stage of star clusters, in the cumulative GWTC-5.0 released by the LIGO-Virgo-KAGRA collaboration. This accretion channel predicts a saturating spin--mass relation, with low spins at low masses, rising continuously with mass through all intermediate spin values, to high spins at high masses. We test this prediction directly against the component spins of the catalogue. We single out 10 events with positive support and many others with weaker support across the whole component-mass range of the catalogue. We identify a preferred mass scale $m^t=20.7^{+11.6}_{-1.2}\,M_\odot$ (90\% credibility) separating regimes with different accretion-mixture fractions, with $\ln B=5.5$. Above this inferred scale, the evidence for an accretion-driven subpopulation is strongly concentrated, reaching a natural log Bayes factor of $16.6$ against the LVK fiducial spin population.
[abstract 45 / 65] (score: 2) - Title: How much of the BLACK HOLE ringdown is sourced within the light ring?Authors: Mark Ho-Yeuk Cheung,Comments: 5 pages, 1 figure, with a 2-page appendixSubjects: gr-qc astro-ph.CO astro-ph.HECreated: 2026-08-29; Updated: 2026-09-01; Datestamp: 2026-09-01
Not much. It has been proposed that applying a rational filter to a BLACK HOLE ringdown gravitational waveform reveals a direct wave component sourced near the event horizon. By solving the Teukolsky equation for a point particle plunging into a Kerr BLACK HOLE, I show that the maximum amplitude of the waves sourced within the prograde light ring is $\lesssim 10\%$ that of those sourced by the full trajectory no matter if the waves are filtered or not. This agrees with the interpretation of quasinormal modes as waves orbiting the light ring and the direct wave as the power of these modes redistributed in time. Therefore, both quasinormal modes and direct waves are more a probe of the light ring than the near-horizon region. For GW250114, I estimate that the component of the waves sourced within the light ring have a signal-to-noise ratio $ρ\lesssim 1$ measured after the peak of the filtered waves.
[abstract 46 / 65] (score: 2) - Title: Photon--Dark Matter Elastic Scattering: An Effective-Operator Scan and First Operator-Resolved Sensitivity Estimates from the Galactic HaloAuthors: Trinity Rosebud Stenhouse, Asli Acar, Mikhail Bashkanov, Frank F. Deppisch, Chamkaur Ghag, Dan P. Watts,Comments: 26 pages, 5 figuresSubjects: astro-ph.HE hep-exCreated: 2026-08-30; Updated: 2026-09-01; Datestamp: 2026-09-01
Elastic photon--DARK MATTER scattering attenuates gamma-ray spectra along a line of sight, probing the same operators as DARK MATTER annihilation to photons but at a rate linear, rather than quadratic, in DARK MATTER density. We consider Standard Model gauge-invariant effective operators of mass-dimension 5 to 7, suppressed by a cutoff scale $Λ$, coupling scalar, Majorana or Dirac DARK MATTER to the photon. The leading operators with non-vanishing real-photon amplitudes enter at dimension-5 for Dirac DARK MATTER and dimension-7 for Majorana DARK MATTER. In the electroweak-doublet dipole portal, the inelastic splitting invoked to evade direct detection also closes the CMB annihilation bound, leaving attenuation the only one of the three photon-sector probes that survives. Applying this to a pixel-level reanalysis of 17 years of \textit{FERMI}--LAT Pass~8 data toward the Galactic centre, we derive the first operator-resolved sensitivity estimates for photon--DARK MATTER scattering from the Galactic halo: $Λ\simeq 0.32~\mathrm{GeV}$ for the dimension-5 Dirac dipoles, $0.21~\mathrm{GeV}$ for the dimension-6 scalar Rayleigh operator and $0.79$--$1.06~\mathrm{GeV}$ for the dimension-7 Rayleigh family. The reach is weak: it lies below the EFT-validity threshold across the cold DARK MATTER mass range, and is superseded on the dipole plane by CMB and direct-detection constraints. The framework is calibrated against pseudo-experiments, and recomputes the sensitivity for any instrument that provides a per-bin spectrum with uncertainties and a line-of-sight column density.
[abstract 47 / 65] (score: 2) - Title: Origin of small-scale evaporation flows deep in the chromosphere during a solar flareAuthors: L. P. Chitta, H. N. Smitha, F. A. Iglesias, T. L. Riethmüller, A. Feller, W. Chen, A. Lagg, A. Gandorfer, J. Hölken, S. K. Solanki, J. C. del Toro Iniesta, Y. Katsukawa, P. Bernasconi, T. Berkefeld, A. Álvarez-Herrero, M. Kubo, D. Orozco Suárez, B. Grauf, M. Carpenter, A. Bell, Valentín Martínez Pillet, F. J. Bailén, J. Blanco Rodríguez, J. Sebastián Castellanos Durán, E. Harnes, R. T. Ishikawa, Y. Kawabata, T. Matsumoto, T. Oba, A. L. Siu-Tapia, H. Strecker, D. Vukadinović,Comments: Accepted for publication in the Astrophysical Journal Letters (Issue: Sunrise III Early Science)Subjects: astro-ph.SR physics.plasm-ph physics.space-phCreated: 2026-08-30; Updated: 2026-09-01; Datestamp: 2026-09-01
Flares are caused by an abrupt release of MAGNETic energy in the solar atmosphere. Plasma heated to well over 10 MK filling the post-flare corona originates from a rapid heating and ablation of the cooler chromospheric material. This chromospheric evaporation is thought to be facilitated primarily by nonthermal electrons impinging on to the lower atmosphere. Questions on when and where in the chromosphere these upflows originate, however, are not fully resolved. Here we report on unprecedented high-resolution observations of an M-class flare recorded by the Sunrise Ultraviolet Spectropolarimeter and Imager on board the balloon-borne SUNRISE observatory, that reveal highly structured upflows on spatial scales of ~100 km originating deep in the chromosphere. The flows even precede the onset of nonthermal electrons by about 10 minutes and last through the impulsive phase of the flare. Our observations shed new light on the lower atmospheric heating and mass circulation in flares that are challenging to reconcile with the standard solar flare model.
[abstract 48 / 65] (score: 2) - Title: Generation of Isolated Collimated Polarized $γ$-ray Beams via Spatiotemporal Optical Vortex ModulationAuthors: Xinyu Xie, Fengyu Sun, Huai-Hang Song, Wei-Min Wang, Wenpeng Wang,Comments:Subjects: physics.plasm-phCreated: 2026-08-30; Updated: 2026-09-01; Datestamp: 2026-09-01
Attosecond, collimated, bright, polarized $γ$-ray sources are in high demand across nuclear physics, astrophysics, and high-energy physics. However, realizing attosecond duration, high collimation, high brilliance, and high POLARIZATION simultaneously within a single isolated source remains an outstanding challenge, owing to the inherent trade-offs between beam trapping and radiative dynamics. Here, we propose a novel scheme to generate an isolated, collimated, high-brilliance, polarized attosecond $γ$-ray beam from conventional solid foils irradiated by a linearly polarized spatiotemporal optical vortex (STOV) LASER pulse accessible in Lab. Three-dimensional spin-resolved particle-in-cell simulations reveal that this RELATIVISTIC-intensity STOV pulse can trap and accelerate electrons at its spatiotemporal singularity, producing a compact isolated electron bunch. This electron bunch subsequently undergoes head-on collision with the reflected LASER pulse, which generates isolated $γ$-ray beams through nonlinear Compton scattering. With a peak intensity of $7\times10^{21}$ W/cm$^2$, we observe an isolated collimated ($\sim1.5^{\circ}$) $γ$-ray beam with an average linear POLARIZATION of $>60\%$ and a duration of $\sim$500 attoseconds. This approach is feasible with current or upcoming LASER facilities and robust against variations in LASER and target parameters, highlighting the capability of spatiotemporal structured light field modulation to address outstanding problems in plasma physics.
[abstract 49 / 65] (score: 2) - Title: Primordial Black Hole Seeds for Little Red Dots in $f(R)$ GravityAuthors: Saeed Fakhry,Comments: 19 pages, 8 figuresSubjects: astro-ph.GA astro-ph.CO gr-qcCreated: 2026-08-30; Updated: 2026-09-01; Datestamp: 2026-09-01
The discovery by the James Webb Space Telescope (JWST) of an abundant population of compact little red dots (LRDs) and supermassive BLACK HOLEs at high redshifts poses a severe timing challenge for standard Eddington-limited growth from stellar remnants. In this work, we present a unified hybrid assembly framework in which intermediate-mass seed BLACK HOLEs are formed via hierarchical primordial BLACK HOLE (PBH) mergers within dense clusters in Hu-Sawicki $f(R)$ gravity, followed by galactic gas accretion. We demonstrate that the screened $f(R)$ fifth force nonlinearly accelerates early seed formation through a quadratic enhancement of the gravitational-wave radiation-capture kernel, while environmental chameleon screening dynamically self-regulates the growth. Because subsequent gas accretion scales multiplicatively with seed mass, the $f(R)$ seed enhancement is preserved throughout the accretion history, drastically reducing the time-averaged Eddington ratios required to assemble $10^{6}\text{-}10^{9}\,M_{\odot}$ LRDs by cosmic dawn. Confronting our active mass functions with JWST data reveals that a small clustered PBH fraction ($f_{\rm PBH} \lesssim 10^{-3}$) under a realistic ACTIVE GALACTIC NUCLEus duty cycle ($δ\approx 10^{-2}$) naturally matches observed LRD space densities at $z \sim 5.5\text{-}6.5$ while remaining fully compliant with LIGO-Virgo-KAGRA limits, with modified gravity naturally driving the high-mass tail. Finally, we show that parameter degeneracies between modified gravity and cluster density can be cleanly broken by combining three multi-messenger diagnostics: remnant spin state signatures, a stochastic GW background cutoff, and a scale-dependent inversion in the PBH spatial correlation function.
[abstract 50 / 65] (score: 2) - Title: Splashing-regime transitions and secondary-droplet scaling in oblique drop impacts on a deep poolAuthors: Ying Xiong, Yang Zhang, Lingling Xie, Xiaolei Li,Comments: 28 pages, 13 figuresSubjects: physics.flu-dyn physics.ao-phCreated: 2026-08-30; Updated: 2026-09-01; Datestamp: 2026-09-01
Oblique drop impact onto a deep liquid pool produces asymmetric crowns, directional JETting, and splashing transitions that cannot be characterized by the total impact inertia alone. We numerically investigate water drops impacting a quiescent deep pool over $41\leq We\leq1790$ and $10^\circ\leqθ\leq90^\circ$. The simulations reproduce the principal features observed experimentally and identify five post-impact regimes in the $We$--$θ$ plane: deposition, front splashing, side splashing, side-front splashing, and crown splashing. The deposition--front-splashing transition is described by the tangential-inertial parameter $K_s=We\cosθ$, with $K_s^c\approx120$. This criterion follows from the competition between downstream crown-rim inertia and capillary retraction at the Taylor--Culick velocity. The transition from front to side-front splashing is instead governed primarily by normal impact inertia, with a critical normal Weber number $We_N^c\approx318$. Beyond these regime transitions, the secondary-droplet statistics reveal fragmentation behavior common to the different splashing regimes. The droplet-size distributions are positively skewed, and the median diameter follows $d_{s,\mathrm{med}}/D\sim We^{-3/5}$. Second-order velocity structure functions support a scale-dependent capillary--inertial description of rim and ligament breakup. Combined with mass conservation, this scaling gives $N_s\sim We^{9/5}$, providing a numerical explanation for the secondary-droplet-number scaling observed experimentally. Thus, directional impact inertia governs the macroscopic selection of splashing regimes, whereas the secondary-droplet populations across these regimes exhibit a common capillary--inertial fragmentation scaling.
[abstract 51 / 65] (score: 2) - Title: Multiscale Synthetic observations of Polarized dust emission: On the origin of DePOLARIZATION effect from Molecular clouds to Starless cores and Constraints on Dust PhysicsAuthors: Nguyen Chau Giang, Thiem Hoang, Blakesley Burkhart, Doris Arzoumanian, Nguyen Bich Ngoc, Jihye Hwang, Aran Lyo,Comments: Accepted to be published in ApJ. 24 pages, 11 figures in Main text, 8 pages in AppendixSubjects: astro-ph.GACreated: 2026-08-30; Updated: 2026-09-01; Datestamp: 2026-09-01
Submillimeter observations of polarized dust emission from molecular clouds to starless cores frequently report a decrease in POLARIZATION fraction (p) with increasing dust emission intensity (I). This feature is commonly attributed to the alignment loss of dust grains or the geometrical effects of MAGNETic fields, yet, the detailed contributions remain unclear. To investigate the mechanism responsible for the dePOLARIZATION, we use POLARIS to perform the multiscale synthetic dust POLARIZATION observations at $850μm$ from MAGNETically aligned dust grains by RAdiative Torques (RATs) mechanism. We adopt three collapsing cloud models with different MAGNETic energy levels and explore the effects of grain MAGNETic properties and grain growth on dust POLARIZATION. The field geometrical effect is the dominant dePOLARIZATION mechanism at $N_{\rm H}<10^{21}-10^{22}\rm cm^{-2}$. We find that if grains grow beyond $>0.5μm$ and are superparaMAGNETic (SPM) with large iron clusters, RATs remain effective at high column densities, and grain alignment loss contributes to dePOLARIZATION only at $N_{\rm H} > 10^{23}\rm cm^{-2}$. If neither of these conditions is satisfied, the alignment loss (in cases of insufficient grain growth); or the reduced grain alignment efficiency by gaseous damping (for paraMAGNETic grains or SPM grains with small iron cluster sizes) can become the dominant dePOLARIZATION mechanism at $N_{\rm H} > 10^{22}\rm cm^{-2}$, regardless of how tangled the MAGNETic field lines in our simulation. Finally, we show that the dePOLARIZATION mechanism and the underlying dust physical properties inside starless cores may be identified through the $p-I$ slope and the mean p at the core center.
[abstract 52 / 65] (score: 2) - Title: Advancing Fundamental Physics and Cosmology with high-resolution X-ray imagingAuthors: Sara Turriziani, Herman L. Marshall, Daryl Haggard, Scott Randall, Mayura Balakrishnan, Tom Maccarone, Nicole Ford,Comments: This is a report generated in response to a call by the X-ray Science Interest Group of the NASA Physics of the Cosmos Program Analysis Group (PhysPAG). A summary of all five reports can be found at https://doi.org/10.48550/arXiv.2606.28138Subjects: astro-ph.HECreated: 2026-08-30; Updated: 2026-09-01; Datestamp: 2026-09-01
Black Holes are the key to solving many unanswered questions in fundamental physics: in particular, the very extreme properties shown by supermassive BLACK HOLEs at the centers of galaxies make them obvious candidates for testing gravity theories in the strong-field regime. Since X-rays are generated by matter under extreme physical conditions, ultra-high resolution X-ray imaging (uXRI) will directly image the region near the event horizon of BLACK HOLEs in X-rays, similar to the Event Horizon Telescope in the radio band, enabling unprecedented tests of General Relativity and alternative theories of gravity near supermassive BLACK HOLEs. On the other hand, clusters of galaxies hold the potential of unveiling many unknowns in cosmology. uXRI will unlock this potential by probing small-scale plasma properties in the intracluster medium, providing the missing link required to establish galaxy clusters as reliable tools for high-precision cosmology. Moreover, uXRI will enable mapping of Dark Matter from galaxy cluster dynamics via proper motion measurements. Finally, uXRI will open a new field of precision X-ray astrometry, allowing for measuring pulsar parallaxes to support nanoHertz gravitational wave searches.
[abstract 53 / 65] (score: 2) - Title: Magnetizing nonlinear plasma wakefields for positron accelerationAuthors: Yung-Kun Liu, Pisin Chen, Ching-En Lin, Spencer Gessner, Bernhard Hidding,Comments:Subjects: physics.acc-ph physics.plasm-phCreated: 2026-08-31; Updated: 2026-09-01; Datestamp: 2026-09-01
It is known that only a narrow plasma wakefield sliver in the electron-beam-driven blowout regime suits positron acceleration. Using 3D simulations, we show that matching the cyclotron frequency $ω_{c}$ with the plasma frequency $ω_{p}$ forms a stable electron column on axis, expanding the suitable phase space for positron acceleration sizably. For a plasma density $n_p = 10^{16}\text{ cm}^{-3}$ in a 35 T field, the interval expands 4.3 times, and a witness positron beam gains 100--150 MeV over 6 cm ($1.6$--$2.5$~GeV/m) with a 92\% capture rate.
[abstract 54 / 65] (score: 2) - Title: Photometric redshifts for ACTIVE GALACTIC NUCLEi with LePHARE for the Vera C. Rubin ObservatoryAuthors: R. Shirley, M. Salvato, J. Cohen-Tanugi, O. Ilbert, S. Arnouts, R. Ansari, R. Assef, M. Banerji, A. Bongiorno, W. N. Brandt, J. Buchner, J. Comparat, D. Ilić, A. Kovačević, J. Kubica, B. Laloux, O. Lynn, A. Malz, L. Marchetti, C. Mazzucchelli, T. Mkrtchyan, K. Nandra, D. Oldag, C. Ricci, W. Roster, E. Saremi, S. Satheesh-Sheeba, T. Tasnim. Ananna, M. J. Temple, M. Vaccari, A. Viitanen, C. Wolf, Z. Yu, T. Zhang,Comments:Subjects: astro-ph.GACreated: 2026-08-31; Updated: 2026-09-01; Datestamp: 2026-09-01
Active Galactic Nuclei (AGN) play a crucial role in galaxy evolution, but they are a minority of extragalactic sources with diverse Spectral Energy Distributions (SEDs), which depend on their means of selection. Upcoming large-scale surveys such as LSST will identify many AGN, but analysis tools are not optimized for them. The limited number of photometric bands in these surveys impacts the calculation of photometric redshifts for AGN, which are essential for scientific advancement. We use LePHARE to demonstrate the impact that a limited number of bands and erroneous assumptions have on the determination of the photometric redshifts of AGN. We conduct tests on six AGN samples selected using X-ray, radio, infrared, variability, color, and spectroscopic criteria in the COSMOS field, using photometry from HSC-CLAUDS, which is closest in depth and wavelength coverage to LSST. We present the LSST pipeline for LePHARE within the Redshift Assessment Infrastructure Layers (RAIL), facilitating comparison between SED fitting and machine learning algorithms. AGN that appear as point-like sources in optical data will be assigned highly unreliable photometric redshifts if they are processed using galaxy templates. Additionally, shallow all-sky surveys (like eROSITA, WISE, and ZTF) miss many AGN. As a result, these ``hidden'' AGN are often misidentified as galaxies in public survey data, leading to incorrect photometric redshift. We provide the configurations that are suggested for each type of AGN alongside measures of expected performance as a function of redshift, magnitude, and selection. To facilitate studies with a panchromatic view of AGN, we also release photometric redshifts and posterior distributions for all AGN sources identified in the COSMOS field using the six criteria, based on 28-band photometry.
[abstract 55 / 65] (score: 2) - Title: The umbrella effect: Magnetic canopy topology modulates spatially averaged chromospheric three-minute powerAuthors: Shahin Jafarzadeh, David B. Jess, Marco Stangalini, Bernhard Fleck, Richard J. Morton, Samuel D. T. Grant, Peter H. Keys, Luc Rouppe van der Voort, Sven Wedemeyer, Tiago M. D. Pereira, Mikołaj Szydlarski, Elias R. Udnæs, Thomas Wiegelmann, Markus Roth,Comments: Accepted for publication in Astronomy & AstrophysicsSubjects: astro-ph.SRCreated: 2026-08-31; Updated: 2026-09-01; Datestamp: 2026-09-01
Three-minute ($\sim$5 mHz) oscillations are a prominent signature of wave propagation in the solar chromosphere, but their measured power can vary substantially between full-disc observations and small, high-resolution fields of view. We investigate whether chromospheric MAGNETic canopy topology, particularly its lateral continuity and areal filling, modulates field-of-view-averaged three-minute power. We analyse H$α$ and Ca II 8542 Å spectral imaging from the Swedish 1-m Solar Telescope, comparing canopy-poor quiet-Sun scenes with canopy-dominated active-region environments, complemented by radiative-MHD Bifrost simulations of canopy-poor and canopy-rich atmospheres. We compute field-of-view-averaged power spectra from fixed-wavelength intensities and bisector-derived velocities in the observations, and from synthetic intensities, velocities, and temperature proxies in the simulations. We also quantify the relation between integrated 3-5 mHz excess power and canopy filling factor, using HMI-based MAGNETic-field extrapolations for the observations. In both observations and simulations, canopy-poor scenes show clear 3-5 mHz power enhancements, whereas canopy-dominated scenes show strongly reduced measured power. The trend is present in H$α$ and Ca II 8542 Å intensities and is supported by complementary velocity and temperature proxies. Integrated 3-5 mHz excess power decreases with increasing canopy filling factor. We conclude that chromospheric field-of-view-averaged three-minute power is a topology-weighted observable: dense, laterally continuous MAGNETic canopies can strongly reduce the measured large-scale three-minute signature without requiring the absence of local wave activity. This provides a practical criterion for interpreting chromospheric oscillation power as a proxy for atmospheric wave energy in the Sun and in MAGNETised cool-star atmospheres.
[abstract 56 / 65] (score: 2) - Title: Magnetohydrodynamics of charged interstellar dust. Multifluid models and study of the linear modesAuthors: Gabriel Verrier, Patrick Hennebelle, Ugo Lebreuilly, Valentin Vallucci-Goy,Comments: Accepted for publication in Astronomy & AstrophysicsSubjects: astro-ph.GA astro-ph.SR physics.plasm-phCreated: 2026-08-31; Updated: 2026-09-01; Datestamp: 2026-09-01
Interstellar grains play key roles in star and planet formation, including the coupling of the gas to the MAGNETic field during the protostellar collapse. These roles depend on the local grain size distribution, which requires a multifluid treatment of charged dust. We aim to understand the fundamental physics of the dynamics of a dust distribution in interaction with the gas and the MAGNETic field. In particular, the purpose is to characterize the (de)coupling conditions of these different components. We provide a multifluid model of charged dust which accounts for the inertia of the grains. A chemical network is used to simulate the charge equilibrium in collapsing protostellar cores. We compute the Alfven modes and the MAGNETosonic modes to understand the coupling regimes between the gas, the dust fluids, and the MAGNETic field. We also analyze and compare to the predictions of existing models, that are the neutral dust multifluid and the standard non-ideal MAGNETohydrodynamics. The charged multifluid model agrees with non-ideal MAGNETohydrodynamics on the larger scales of a collapsing dense core and the forming disk, while we successfully extend to new regimes where the inertia of dust grains matters. We found that high charge-to-mass dust grains carry the propagation of MAGNETohydrodynamical waves in protostellar envelopes. We provide analytical expressions of the speed of these waves depending on the dust distribution. The MAGNETocompressive perturbations lead to local dust-to-gas ratio variations at au scales. A theoretical understanding of the dynamics of a charged dust distribution is provided in the linear regime. The closed set of MAGNETohydrodynamics equations can be implemented in numerical codes to explore nonlinear effects during the protostellar collapse such as turbulence, angular momentum transport and MAGNETic dust clumping.
[abstract 57 / 65] (score: 2) - Title: External MAGNETic-field effects on dipolar-particle orbits and critical collisions in Kerr--Bertotti--Robinson spacetimeAuthors: Haowei Chen, Hengyu Xu, Shao-Jun Zhang,Comments: 21 pages, 13 figures, 5 tablesSubjects: gr-qcCreated: 2026-08-31; Updated: 2026-09-01; Datestamp: 2026-09-01
Strong MAGNETic fields affect particle dynamics through two distinct channels: gravitational backreaction deforms the spacetime, while direct coupling to an intrinsic MAGNETic moment depends on the relative orientation of the field and the dipole. We disentangle these effects by studying equatorial orbits and near-horizon collisions of electrically neutral MAGNETized particles in the exact Kerr--Bertotti--Robinson spacetime. The field-induced geometric deformation shifts turning points and circular-orbit domains and can eliminate a finite effective-potential well together with its bound orbits. Even without direct dipole coupling, it can also offset the Kerr periapsis advance and produce a finite-radius zero-precession orbit. Direct dipole coupling breaks the symmetry under MAGNETic-field reversal and shifts the radius, energy, and angular momentum of the innermost stable circular orbit in an orientation-dependent manner. The formal ultraRELATIVISTIC endpoints of these orbit branches, however, remain fixed by the background geometry and approach circular null orbits. In the Bañados--Silk--West mechanism, both MAGNETic effects modify finite-radius potential barriers and hence the ability of a critical particle to reach the near-horizon collision region. In the representative nonzero-field cases examined here, an exactly critical particle released from infinity is blocked before reaching an extremal horizon, although a locally admissible collision between critical and usual particles can still produce unbounded center-of-mass energy. Finite dipole coupling shifts the barriers but does not change the leading near-horizon divergence. Near a nonextremal horizon, an exactly critical particle is excluded and the collision energy remains finite.
[abstract 58 / 65] (score: 2) - Title: Production of the $ϕ$ and $Ω$ via recombination of JET parton showers in RELATIVISTIC heavy ion collisionsAuthors: Kyong Chol Han, Sungtae Cho, Su Houng Lee,Comments: 11pages, 9 figuresSubjects: nucl-thCreated: 2026-08-31; Updated: 2026-09-01; Datestamp: 2026-09-01
We study the production of the $ϕ(1020)$ and $Ω(1672)$ in heavy ion collisions at $\sqrt{s_{NN}} = 5.02$ TeV by employing two complementary approaches. In the first approach, the production of the $ϕ$ and $Ω$ is discussed in the coalescence model. In the second approach, we developed a hybrid framework that combines the recombination of shower and thermal partons with remnant string fragmentation. Thermal partons in the QUARK-gluon plasma are modeled using a blast-wave parameterization, while the phase space information of medium-modified parton showers is generated from Q-PYTHIA, using unquenched JET partons obtained from HIJING initial inputs. We show that both approaches agree well with the experimental measurements, and demonstrate that this hybrid framework provides deeper insight into the underlying strangeness components in the production of $ϕ$ and $Ω$ in RELATIVISTIC heavy-ion collisions.
[abstract 59 / 65] (score: 2) - Title: The Structure of Merging Turbulent Jets Beneath a Small QuadrotorAuthors: Anoop Kiran, Nora Ayanian, Kenneth Breuer,Comments: 20 pages, 11 figuresSubjects: physics.flu-dyn cs.ROCreated: 2026-08-31; Updated: 2026-09-01; Datestamp: 2026-09-01
The downwash wake of a hovering quadrotor governs both the vehicle's own performance and the safe spacing of multi-rotor formations. Prior measurements have largely characterized the mean flow, using single-point anemometry, volumetric tracking, or planar cuts through part of the rotor system. Higher-order turbulent statistics of the merged wake, and how they relate to canonical JET scaling, have remained unresolved, particularly for small quadrotors at the low-Reynolds-number end of the size range. Here, we present a detailed particle image velocimetry (PIV) study of the downwash of a hovering Crazyflie 2.1 quadrotor (arm length, $l = 46$ mm), sampled along a diagonal cut, passing through rotors along the symmetry axis of the quadrotor, and a front-rotor cut, passing through adjacent rotors. The four rotor JETs merge into a single column by $z/l \approx 5$, beyond which the mean velocity profiles progressively approach the canonical round-JET self-similar form, collapsing by $z/l \approx 13$ when scaled by the local centerline velocity and half-width. Centerline decay and half-width growth follow canonical scaling laws with an effective source diameter $D_\text{eff} = 2.29\,l$, effective Reynolds number $Re_{D_\text{eff}} = 3 \times 10^4$, at the low end of the range over which canonical JET scaling has been established, and spreading and decay constants nonetheless within the canonical round-JET range. Resolving both cuts shows that the turbulent normal stresses retain a bimodal, cut-dependent signature of the four-rotor source throughout the measurement domain.
[abstract 60 / 65] (score: 2) - Title: Measuring peculiar velocity and tomographic redshift dipole with DESI DR1 catalogsAuthors: Yi-Wen Wu, Jun-Qing Xia,Comments: 11 pages, 1 figures, 3 tablesSubjects: astro-ph.COCreated: 2026-08-31; Updated: 2026-09-01; Datestamp: 2026-09-01
The so-called ``cosmic dipole tension'' challenges the Cosmological Principle by positing a discrepancy between the Solar System's peculiar velocity inferred from the Cosmic Microwave Background (CMB) dipole and that derived from large-scale structure number-count dipoles. Here we provide a high-precision determination of the kinematic dipole using the redshift-dipole method applied to the first data release (DR1) of the Dark Energy Spectroscopic Instrument (DESI). By exploiting the Doppler-induced modulation of observed redshifts, this estimator is intrinsically less sensitive to imaging systematics and selection-function uncertainties that can bias traditional number-count measurements. We conduct a tomographic analysis of four tracer populations, Bright Galaxy Sample, Luminous Red Galaxies, Emission Line Galaxies, and QUASARs, spanning $0.1
[abstract 61 / 65] (score: 2) - Title: The DSA/Chronoscope fast radio burst survey: forecasts and science overviewAuthors: Liam Connor, Kaitlyn Shin, Vikram Ravi, Stella Koch Ocker, Casey J. Law, Kritti Sharma, Samuel McCarty, Gregg Hallinan, Shami Chatterjee, James M. Cordes, Dean Howarth, Fabian Walter, Elisabeth Krause, Vishnu Balakrishnan, Alexa C. Gordon, Calvin Leung, Shion Andrew,Comments:Subjects: astro-ph.HE astro-ph.CO astro-ph.IMCreated: 2026-08-31; Updated: 2026-09-01; Datestamp: 2026-09-01
Fast radio bursts (FRBs) are bright extragalactic transients with several mysteries surrounding their origins. Large FRB samples enable accurate measurements of the cosmic matter distribution, in particular on scales $\lesssim 10$ Mpc. These measurements will impact cosmological inference and our understanding of astrophysical feedback, from the circumgalactic medium to cluster scales. Here we forecast the expected yields, redshifts, and host galaxies of FRBs as observed by the Deep Synoptic Array (DSA), and describe the key science cases enabled by the large FRB sample. The DSA will be an interferometer consisting of 1650$\times$6.15 m antennas, operating between 0.7--2 GHz, to be located in Nevada, USA. The Chronoscope backend on the DSA, hereafter DSA/Chronoscope, is designed to search for FRBs across the field of view in real time, enabling the storage of full-POLARIZATION voltage data. Extrapolating from existing FRB surveys, we expect roughly $10^4$ FRB detections per year in each of three search sub-bands. Combining across sub-bands, the survey could produce $\sim$ 10$^5$ FRBs over the nominal 5-year DSA survey, assuming Euclidean source counts and a baseline compute backend that can search $6\times10^6$ beams at 1 ms sampling. The well-characterized DSA synthesized beam and deep simultaneous reference images will enable localization precisions of $\lesssim$ 250 milliarcseconds. Key science cases include the use of FRB propagation effects in probing cosmic baryons, and studies of the FRB phenomenon using FRB host galaxies and their local environment, as well as multiwavelength counterparts.
[abstract 62 / 65] (score: 2) - Title: Saha's ionization in the Schwarzschild spacetimeAuthors: Lázaro L. Sales, Jonatas A. Silva, Amilcar R. Queiroz,Comments: 7 pages and 3 figuresSubjects: gr-qc physics.plasm-phCreated: 2026-08-31; Updated: 2026-09-01; Datestamp: 2026-09-01
We investigate the Saha ionization equilibrium in the exterior Schwarzschild spacetime. Starting from the mass-shell condition for a massive particle, we derive the conserved energy associated with the timelike Killing symmetry and obtain its nonRELATIVISTIC limit in terms of the Schwarzschild lapse function. This energy is then incorporated into the Maxwell--Boltzmann distribution to construct the ionization balance as seen by an asymptotic observer. We show that the gravitational field modifies the Saha relation through the redshift of both the particle energies and the thermodynamic variables. By imposing the Tolman--Ehrenfest and Klein equilibrium conditions, the formulation expressed entirely in terms of locally measured quantities reduces to the standard flat-spacetime Saha equation. We further analyze the gravitational redshift of the ionization energy, the relative departure from the flat-spacetime ionization ratio, and the corresponding shift of the ionization fraction as a function of the asymptotic temperature. We also present the RELATIVISTIC classical counterpart based on the Maxwell--Jüttner distribution and show explicitly that its leading correction is negligible in the temperature range where neutral hydrogen is appreciably abundant. These results provide a consistent description of ionization equilibrium in a static gravitational field and clarify the distinction between gravitational redshift effects and intrinsic modifications of local atomic physics.
[abstract 63 / 65] (score: 2) - Title: Constraining equation of state of neutron star using neutron star-BLACK HOLE mergersAuthors: Vasudev Dubey, Rahul Kashyap, Yugesh Bhoge,Comments:Subjects: gr-qc astro-ph.HECreated: 2026-08-31; Updated: 2026-09-01; Datestamp: 2026-09-01
In this work, we study tidal effects that can be observed in gravitational wave transient from neutron star-BLACK HOLE (NSBH) mergers. It has been well known that neutron star's tidal deformation has imprint of equation of state and hence composition of neutron star matter. Compared to binary neutron star mergers, where we observe a combined effect of two neutron stars by measuring the parameter known as lambda tilde. In neutron star BLACK HOLE mergers, we measure the tidal deformability of the neutron star component clearly. In this work, we study the feasibility of measuring the bare tidal deformability of a neutron star with planned gravitational detectors in the near and far future. We use the parameter estimation computation framework, Bilby is used to perform Bayesian inference for hundreds of NSBH mergers in current and future GW detector networks and obtain the posterior probability distribution functions of binary parameters. We find that we need at least 20 events to clearly distinguish the equation state of neutron stars in future detectors, including the Einstein Telescope and Cosmic Explorer.
[abstract 64 / 65] (score: 2) - Title: ALMA CO(2-1) Gas Dynamics in NGC 315: A Multi-Method Benchmark for Supermassive Black Hole Mass MeasurementAuthors: Dieu D. Nguyen, Benjamin D. Boizelle, Hai N. Ngo, Elena Gallo, Tuan N. Le, Sabine Thater, Tien H. T. Ho, Tinh Q. T. Le, Que T. Le, Sam Norcross, Xueyi Li, Huy G. Tong, Nghi K. N. Le, Huy M. B. Tran,Comments: 26 pages, 12 Figures, 3 Tables. Accepted to ApJSubjects: astro-ph.GACreated: 2026-08-31; Updated: 2026-09-01; Datestamp: 2026-09-01
We present ALMA Cycle~7 \cotwo\ observations of the circumnuclear disk in NGC~315 at an angular resolution of $0\farcs230\times0\farcs175$, improving on past measurements and resolving the sphere of influence (SOI) of the supermassive BLACK HOLE (SMBH), whose mass has previously been estimated of $M_{\rm BH}= \left(2.08^{+0.33}_{-0.15}\right) \times 10^9$~M$_\odot$ The high spatial resolution and sensitivity enable robust full-cube forward modeling of the molecular gas kinematics and a direct comparison of multiple independent gas-based dynamical modeling techniques. We apply standard Bayesian codes using both MCMC and nested sampling approaches, as well as a frequentist code to the same dataset, exploring systematic uncertainties associated with the stellar mass distribution, gas surface-brightness parameterization, and disk geometry. All methods yield consistent BLACK HOLE masses, indicating that the inferred $M_{\rm BH}$ is not strongly method-dependent. Combining the ensemble of independent molecular-gas-based models, we derive an ensemble median BLACK HOLE mass of $M_{\rm BH}/10^9\,\mathrm{M_\odot} = 2.02^{+0.04}_{-0.05}$(stat)$^{+0.05}_{-0.04}$(sys), where the comparable contributions to the full error budget arise from modeling systematics rather than formal fitting uncertainties. Our $M_{\rm BH}$ is consistent with the empirical $M_{\rm BH}$--$σ_\star$ and $M_{\rm BH}$--$L_{\rm bulge}$ scaling relations, and lies 32\% below an independent stellar-dynamical measurement, a discrepancy we discuss in the context of systematic differences between gas- and stellar-based methods. NGC~315 serves as a benchmark for quantifying molecular gas-dynamical $M_{\rm BH}$ systematic uncertainties and for future cross-comparisons of gaseous and stellar dynamical approaches.
[abstract 65 / 65] (score: 2) - Title: Bekenstein--Hod Bound: A $3.3σ$ Confirmation from GW250114Authors: Hai-Tian Wang, Shao-Peng Tang, Yi-Zhong Fan,Comments: 9 pages, 2 figures, 1 tableSubjects: gr-qc astro-ph.HECreated: 2026-08-31; Updated: 2026-09-01; Datestamp: 2026-09-01
Black holes link gravity, thermodynamics and information via limits on the relaxation rate of a perturbed system. The Bekenstein-Hod bound imposes a minimum relaxation time at fixed temperature, but its observational test demands both BLACK HOLE thermodynamic characterization and decay time measurement. Here we test this bound with GW250114, the loudest gravitational-wave signal yet observed from a binary black-hole merger. We infer the remnant temperature from pre-merger data truncated at least $10\,M$ before the peak and its longest-lived decay time from post-merger data, thereby avoiding direct reuse of the same strain samples. The ringdown frequencies and damping times are allowed to vary independently rather than being fixed to the Kerr spectrum. For the primary $t_{<}=-10\,M$ analysis, the bound is verified at $3.3-3.6σ$ across the focal ringdown start times, representing a substantial improvement over the $91\%$ confidence level set by GW150914. The conclusion remains robust under varied pre-merger cutoffs and explicit inclusion of the short-lived first overtone in waveform modelling. This separated-data measurement converts an information-theoretic relaxation bound into a precision test of a single astrophysical BLACK HOLE.
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