Current date: 2026-06-02
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Scoring abstracts
Number of records retrieved: 1097
Keyword score statistics
score 13 -- 1 abstracts
score 10 -- 2 abstracts
score 8 -- 1 abstracts
score 7 -- 3 abstracts
score 5 -- 3 abstracts
score 4 -- 5 abstracts
score 3 -- 11 abstracts
score 2 -- 27 abstracts
in total -- 53 abstracts
Articles that appeared on 2026-06-02
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[abstract 1 / 53] Wow! (score: 13)
- Title: High-Synchrotron-Peaked BL Lacs as Multi-Messenger Sources: Connecting Ultra-High-Energy Cosmic Rays and NeutrinosAuthors: Luiz Augusto Stuani Pereira, Rita C. Anjos,Comments:Subjects: astro-ph.HECreated: 2026-05-30; Updated: 2026-06-02; Datestamp: 2026-06-02
High-SYNCHROTRON-peaked (HSP) BL Lac objects are extreme particle accelerators whose SYNCHROTRON emission peaks at high frequencies, typically in the UV-to-X-ray band ($ν_{\rm peak} > 10^{15}$ Hz; $ν_{\rm peak} \geq 10^{17}$ for EHSPs), implying electron Lorentz factors of order $10^5-10^6$. Their relative proximity ($z \geq 0.5$), clean radiation environments, and favorable Hillas parameters make them prime candidates for ultra-high-energy COSMIC RAY (UHECR) acceleration beyond $10^{19}$ eV and for neutrino production above 100 TeV. The 2017 association of IceCube-170922A with the flaring BLAZAR TXS 0506+056 provided compelling evidence for BLAZARs as neutrino sources, while an archival neutrino flare from 2014-2015 with no clear electroMAGNETic counterpart (13 events) revealed additional complexity in the emission mechanism. This review examines HSP physical properties, identifies them through WISE-based infrared selection (the 2WHSP and 3HSP catalogs, approximately 2000 sources), and contrasts leptonic SYNCHROTRON self-Compton models with hadronic alternatives. We assess the observational evidence linking HSPs to high-energy neutrinos and UHECRs, finding that extreme baryonic loading ($L_p/L_e \sim 10^3-10^5$) strains energetic budgets, Auger composition measurements favor heavy nuclei over proton-dominated scenarios, and the near-isotropy of UHECR arrival directions is difficult to reconcile with rare beamed sources. Potential resolutions involving MAGNETic RECONNECTion, structured JETs, and duty cycle effects are discussed. Next-generation facilities, including IceCube-Gen2, KM3NeT, CTAO, IXPE, and AugerPrime/TA x 4, will probe key observables to either establish HSP BL Lacs as sources of the highest-energy cosmic particles or redirect the search toward alternative accelerator classes.
[abstract 2 / 53] Wow! (score: 10) - Title: The Radio--X-ray Correlation of High-Redshift AGN: A Numerical Study of Inverse-Compton Scattering of the CMB Photons in Relativistic JetsAuthors: Aditya Sharma, Bhargav Vaidya, Silvia Belladitta, Christian Fendt, Dharam V. Lal, Eduardo Bañados, Biman B. Nath, Harshita Bhuyan,Comments:Subjects: astro-ph.HE astro-ph.GACreated: 2026-05-30; Updated: 2026-06-02; Datestamp: 2026-06-02
Relativistic JETs from ACTIVE GALACTIC NUCLEi are expected to exhibit strong redshift evolution in their radiative output due to the increasing energy density of the cosmic microwave background (CMB). We investigate the role of inverse Compton (IC) scattering of CMB photons in regulating the radio and X-ray emission from large-scale JETs using three-dimensional RELATIVISTIC MAGNETohydrodynamic simulations coupled with a hybrid Eulerian-Lagrangian particle framework. By keeping the JET dynamics and ambient medium properties fixed across redshifts, we are able to isolate the impact of the cosmological evolution of the CMB on the JET radiation. From our simulations, we construct synthetic spectral energy distributions and intensity maps considering SYNCHROTRON and IC/CMB losses along with particle acceleration from shocks. We are able to reproduce the weak redshift dependence of radio luminosity and the strong enhancement of X-ray emission toward high redshift that is observed in radio-loud QUASARs. At high redshift, the X-ray luminosity follows the expected $(1+z)^4$ scaling, confirming IC/CMB as the dominant mechanism driving the X-ray enhancement. The resulting X-ray-to-radio flux ratio increases systematically with redshift and is consistent with observational constraints. Finally, we show that slower JETs exhibit a stronger redshift evolution of the X-ray enhancement than faster JETs, highlighting the critical role of JET propagation length scales and particle energy evolution. The simulations also naturally reproduce the steepening of the radio spectral index with redshift - the $α$-$z$ relation - thus providing a unified framework that allows to interpret the multiwavelength properties of high-redshift radio sources.
[abstract 3 / 53] Wow! (score: 10) - Title: TeV gamma-ray spectral spikes produced by MAGNETic RECONNECTion in BLAZAR JETs: the case of the 2014 high state of Markarian 501Authors: João G. Giesbrecht Formiga Paiva, Elisabete M. de Gouveia Dal Pino, Juan C. Rodríguez-Ramírez, Ulisses Barres de Almeida, Gabriela B. Díaz-Cortés,Comments: Accepted for publication in JHEAPSubjects: astro-ph.HECreated: 2026-05-30; Updated: 2026-06-02; Datestamp: 2026-06-02
Multi-wavelength monitoring of the flaring BLAZAR Markarian 501 during July 2014 revealed a TeV gamma-ray spike feature with 3-4$σ$ significance and coincident with a prominent enhancement in its X-ray flux. The appearance of this spectral feature strongly suggests the presence of an extra emission component in addition to the usual one-zone SSC scenario. Several possible explanations for the origin of this novel behavior have been discussed, including stochastic particle acceleration, MAGNETospheric vacuum gap, and pion decay. In this paper, we show that the TeV narrow feature, simultaneous with an increase in the X-ray flux, can be produced with two leptonic emission regions in a JET undergoing MAGNETic RECONNECTion energy dissipation along its propagation axis. In this scenario, the stable spectral components are produced in the region of maximum MAGNETic dissipation. A second region produces a flare upstream in the JET in a slower, more MAGNETized, and much smaller region compared to the stable one, which is responsible for increasing the X-ray flux and producing the TeV spike. The macroscopic properties of these two emission regions are consistent with a MAGNETically striped JET model discussed in previous works, where the acceleration of the JET flow and its non-thermal emission is driven by turbulent-induced MAGNETic RECONNECTion. We employ this JET-RECONNECTion scenario to model the 2014 high state of the BLAZAR Markarian 501, considering the sequence of SED datasets corresponding to MJD 56855.91, 56857.98, 56858.98, and 56859.97, with the second dataset being the one that exhibits the TeV spike.
[abstract 4 / 53] Wow! (score: 8) - Title: Hard X-ray Sources in FERMI UFOsAuthors: Alessandro Paggi, Ioannis Liodakis, John Antoniadis, Chien-Ting Chen, Steven R. Ehlert, Daniel Gruen, Philip Kaaret, Ignacio De La Calle Perez, Elena Jimenez Bailon, Mykhailo Ilin,Comments: 29 pages, 11 tables, 7 figures, accepted for publication on ApJSubjects: astro-ph.HECreated: 2026-05-29; Updated: 2026-06-02; Datestamp: 2026-06-02
Identification and/or association of unidentified $γ$-ray sources with lower-energy counterparts represents a key challenge in modern astronomy, due to the relatively large positional uncertainty provided by $γ$-ray detectors. We selected Unidentified FERMI Objects (UFOs) positionally compatible with hard X-ray sources in the latest Palermo SWIFT-BAT hard X-ray Catalog and in the SRG/ART-XC all-sky X-ray survey Catalog, to identify lower-energy sources and possibly associate them to the UFOs. We found 17 UFOs with overlapping hard X-ray sources. We then collected soft X-ray data from SWIFT-XRT, Chandra-ACIS, XMM-Newton-EPIC, and eROSITA, identified 16 soft X-ray counterparts to the hard X-ray sources, and associate 15 with known astronomical objects, classified as: BLAZARs/BLAZARs candidates (2 sources), Seyfert galaxies (5 sources), X-ray binaries (2 sources), generic X-ray sources (1 source), cataclysmic variables (2 sources), and variable stars (3 sources). Blazars and Seyfert galaxies are likely lower-energy counterparts to the UFOs, since their mid-IR colors and broad-band spectral energy distributions suggest significant JETted, non-thermal emission. X-ray binaries can be potential lower-energy counterparts to the UFOs, since this class of sources has been already observed to emit $γ$-rays. The generic X-ray source has been proposed as a pulsar candidate, and we therefore suggest that it can be the lower-energy counterpart to the UFO. Cataclysmic variables have been suggested as potential $γ$-ray emitters so, if confirmed, the 2 sources classified as cataclysmic variables would represent the first $γ$-ray emitting sources of this kind. Finally, we consider the association of the 3 variable stars with the UFOs unlikely.
[abstract 5 / 53] Wow! (score: 7) - Title: Radiation GRMHD Models of Accretion onto Stellar-Mass Black Holes: III. Near-Eddington AccretionAuthors: Lizhong Zhang, James M. Stone, Shane W. Davis, Yan-Fei Jiang, Patrick D. Mullen, Christopher J. White,Comments: 29 pages, 24 figures, 3 tables, submitted to ApJSubjects: astro-ph.HECreated: 2026-06-01; Updated: 2026-06-02; Datestamp: 2026-06-02
We present a comprehensive analysis of four near-Eddington BLACK HOLE accretion models computed by solving the GRMHD equations with full radiation transport. This study focuses on the dynamical effects of MAGNETic field topology and BLACK HOLE spin. Two stable near-Eddington solutions emerge in these models: a thin thermal disk embedded within a MAGNETic envelope when sufficient net vertical MAGNETic flux is present (e.g., vertical field $\gtrsim 5\times10^5$ G at $20r_g$), and a MAGNETically elevated disk when the net vertical flux is weak or absent. One model initialized without net vertical flux is found to evolve into the thin disk solution, as strong, anisotropic radiation feedback at high accretion rates promotes the accumulation of vertical MAGNETic flux in the inner disk. In the thin thermal disk, accretion is driven primarily by mean-field Maxwell stress and proceeds largely within the MAGNETic envelope, while heat dissipation is spatially decoupled and concentrated near the midplane. However, in the MAGNETically elevated disk, accretion occurs throughout the disk body and is comparably driven by mean-field and turbulent stresses; heat dissipation therefore occurs locally through turbulence. Radiation transport is diffusion-dominated, enabling efficient radiative cooling ($\sim$4-10%). An optically thin wind is launched from the disk surface by combined radiative and MAGNETic forces, with its strength increasing with BLACK HOLE spin and vertical MAGNETic flux. Both strong and weak JETs are produced in these models: strong JETs are persistent, highly RELATIVISTIC, and MAGNETically driven, while weak JETs are intermittent, mildly RELATIVISTIC, and powered by a combination of MAGNETic and radiative forces.
[abstract 6 / 53] Wow! (score: 7) - Title: Far-infrared SYNCHROTRON properties of the inner lobes of the RADIO GALAXy Centaurus A revealed with the Herschel observatoryAuthors: Naoki Isobe, Motoki Kino, Takao Nakagawa, Shunsuke Baba, Makoto Tashiro, Hiroshi Nagai,Comments: 11 pages, 7 figures, 1 table, accepted for PASJSubjects: astro-ph.HE astro-ph.GACreated: 2026-05-29; Updated: 2026-06-02; Datestamp: 2026-06-02
Diffuse far-infrared SYNCHROTRON emission filling the northern inner lobe of the RADIO GALAXy Centaurus A is investigated with the Spectral and Photometric Imaging Receiver onboard the Herschel observatory at its three photometric bands. The far-infrared flux density spatially integrated over the lobe is measured as $S_{\rm ν} = 1.63 \pm 0.05$ Jy at the wavelength of $500$ $μ$m (the frequency of $600$ GHz). A comparison between the far-infrared spectral index derived with Herschel ($α= 1.32 \pm 0.19$) and the radio index ($α= 0.66 \pm 0.04$) suggests a spectral break between these frequency ranges. The change of the spectral index through the break is indicated to be consistent with that of the standard cooling break ($Δα= 0.5$) predicted for particle acceleration under the continuous energy injection condition. A broken power-law model incorporating the standard cooling break yields the break frequency as $ν_{\rm b} = 218 \pm 83$ GHz. From the measured cooling break frequency, the MAGNETic field of the northern inner lobe is evaluated as $B \gtrsim 100$ $μ$G. It is quantitatively estimated that the adiabatic cooling puts only a minor impact on the derived MAGNETic field. This MAGNETic field is higher than that under the minimum-energy condition by more than a factor of $5$. In addition, the derived MAGNETic field of the lobe is suggested to be at least by a factor of $4$ stronger than that of the inner-JET region implied in the previous very-high-energy gamma-ray study. Even if the line-of-sight orientation of the lobe is considered in its possible extreme case, the MAGNETic field is found to be reduced only by a factor of 2, and the above arguments about the strong MAGNETic field basically holds. The science impact of this result is discussed from the viewpoints of JET energetics, and of ultra-high energy COSMIC RAYs.
[abstract 7 / 53] Wow! (score: 7) - Title: Locating the Production Sites of High-Energy Neutrinos in Blazar JetsAuthors: Rui Xue, Yoshiyuki Inoue, Ze-Rui Wang, Neng-Hui Liao, Dingrong Xiong,Comments: 19 pages, 6 figures, 5 tables, submitted to ApJ. Suggestions, comments or feedback will be appreciated!Subjects: astro-ph.HECreated: 2026-06-01; Updated: 2026-06-02; Datestamp: 2026-06-02
The production sites of high-energy neutrinos in BLAZAR JETs remain poorly constrained. In this work, we investigate the physical conditions required for efficient neutrino production by combining radio-constrained JET properties with multi-zone emission modeling. We show that efficient neutrino production requires an external radiation field stronger than the MAGNETic field in the JET frame. This environment not only enhances the efficiency of photohadronic interactions but also suppresses SYNCHROTRON radiation from secondary pairs, thereby avoiding overshooting the hard X-ray data. Such conditions can be achieved in regions near or within the broad-line region. However, assuming a single emission zone, these conditions are generally inconsistent with the double-bump flux ratio of the observed broadband emission. This implies that the neutrino-emitting region should be physically separated from the dominant electroMAGNETic emission zone. We further show that such a scenario can be realized either if the JET completes its acceleration within sub-parsec scales or if the bulk Lorentz factor is intrinsically large, both of which appear uncommon based on current observations. These results provide a natural explanation for the rarity of BLAZAR-neutrino associations and highlight the importance of constraining JET structure at small scales to identify promising neutrino-emitting BLAZARs.
[abstract 8 / 53] Yes (score: 5) - Title: Reconnection-Driven Turbulent Fluctuations in the Magnetically Dominated Collisionless RegimeAuthors: Yue Hu, Luca Comisso, Lorenzo Sironi, Siyao Xu,Comments: 23 pages, 23 figures, accepted for publication in ApJSubjects: astro-ph.GA physics.plasm-phCreated: 2026-05-31; Updated: 2026-06-02; Datestamp: 2026-06-02
Magnetic RECONNECTion is a fundamental plasma process that converts MAGNETic energy into bulk flow energy, thermal energy, and nonthermal particle acceleration. Despite its importance, the statistical properties of the turbulent fluctuations generated by collisionless RECONNECTion, which are essential for understanding how this energy conversion proceeds, remain poorly understood. Here, we employ large-scale 3D particle-in-cell simulations to investigate the turbulence characteristics of velocity and MAGNETic field fluctuations generated by collisionless RECONNECTion in a MAGNETically dominated pair plasma. We characterize their statistical properties by computing structure functions along different directions within the RECONNECTion layer. We find that the square root of the second-order velocity structure function follows a power-law scaling with a slope $\sim1/3$ at intermediate to large scales. The square root of the second-order MAGNETic structure function consistently exhibits a steeper slope, in the range $\sim 0.6 - 0.8$. The presence of a finite guide field does not systematically modify the slope of the velocity fluctuations, while it progressively steepens the scaling of the MAGNETic fluctuations in the guide-field and inflow directions. We measure higher-order structure functions, which reveal strong MAGNETic intermittency along the outflow direction and weaker intermittency in the inflow and guide-field directions. Additionally, the local anisotropies of both velocity and MAGNETic field fluctuations are greater for stronger guide fields. These results provide a systematic characterization of the multiscale nature of turbulence in collisionless and MAGNETically dominated RECONNECTion layers, with important implications for plasma heating and particle acceleration.
[abstract 9 / 53] Yes (score: 5) - Title: Comparative properties of X-Ray Flashes and Gamma-Ray Bursts from BeppoSAX observations of Fast X-ray TransientsAuthors: L. Piro, G. Gianfagna, J. J. M. in't Zand, B. Gendre, C. Guidorzi, L. Amati, F. Frontera, E. Kuulkers,Comments: 17 pages, 18 figures. Submitted to A&ASubjects: astro-ph.HECreated: 2026-05-29; Updated: 2026-06-02; Datestamp: 2026-06-02
We present the homogeneous and complete sample of 96 bona-fide Gamma Ray Bursts (GRBs) detected by the Wide Field Cameras and Gamma Ray Burst Monitor of BeppoSAX. We derive the spectral and temporal properties of the prompt emission, and assess the properties of the soft population of GRB, namely X-ray flashes (XRFs) in comparison with normal GRBs. We find that 36 events are XRFs, 40 X-ray rich events (XRR), and 20 normal GRBs. We analyze the distribution of the spectral parameters of the Band function, finding that the spectral indexes of the three classes are broadly similar. On the contrary the peak energy is the parameter driving the spectra shape, from 8.5 keV for XRF keV to 83 keV for GRBs. For the 67 events that are detected in both instruments we find that 9 events exhibit a soft X-ray precursor taking place from 14 to 105 s before the onset of the GAMMA-RAY BURST. About 90\% of the events that were identified in real time exhibit an X-ray afterglow, with a similar fraction for the three classes. In the optical and radio the the corresponding fractions are 35% and 33%. All the similarities in the spectrum, duration and afterglow properties suggest common progenitors for the three classes, where the differences are likely a combination of the effect of different baryon loading, energy, structure and orientation of the JET with respect to the observer. A comparison with Einstein Probe shows that the latter, thanks to its sensitivity, reaches out to a population of fainter and more numerous events, whose presence was firstly hinted at by the unique very low luminosity BeppoSAX GRB980425.
[abstract 10 / 53] Yes (score: 5) - Title: A 0.03 Hz Radio Quasi-periodic Oscillation During the 2025 Flare of GRS 1915+105Authors: Ya Xing Li, Lei Liu, Wu Jiang, Zhen Yan, Bo Xia, Zhi Qiang Shen,Comments: 10 pages, 3 figures. Accepted for publication in ApJSubjects: astro-ph.HECreated: 2026-06-01; Updated: 2026-06-02; Datestamp: 2026-06-02
Our weekly-cadence radio monitoring campaign captured a bright flare in 2025 from the microQUASAR GRS 1915+105, observed simultaneously in the S- and X-bands (2.25 GHz and 8.42 GHz) with a short single baseline of two radio telescopes in Shanghai. Through high time resolution analysis, we detected a significant and short-lived quasi-periodic oscillation (QPO) at $\sim$0.03 Hz and its harmonic ($\sim$0.06 Hz) in both radio bands of two consecutive observations on MJD 60765 ($>5.9 σ$) and MJD 60772 (2.8$σ$). Crucially, the QPO frequency is identical in both radio bands and matches oscillations detected in previous years. The recurrence and wavelength independence of the QPO frequency suggest an intrinsic characteristic timescale of the accretion-JET system.
[abstract 11 / 53] Yes (score: 4) - Title: Resolving the (Debate About) Nozzle Shocks in Tidal Disruption EventsAuthors: Zachary L. Andalman, Eliot Quataert, Eric R. Coughlin, C. J. Nixon,Comments: 19 pages main body, 23 pages total, 17 figures. Accepted by OJA on June 1st, 2026. Resubmitted for 2nd review on May 8th, 2026. Originally submitted to OJA on Dec 10th, 2025. Comments welcome. The code to generate our EOS tables is available at https://zandalman.com/publications/Andalman+2026a/Subjects: astro-ph.HECreated: 2026-06-01; Updated: 2026-06-02; Datestamp: 2026-06-02
When a star passes within the Roche limit of a supermassive BLACK HOLE (SMBH), it is pulled apart by the BH's tidal field in a tidal disruption event (TDE). The resulting flare is powered by the circularization and accretion of bound stellar debris, which initially returns to the BH on eccentric orbits in a thin debris stream. The returning fluid elements follow inclined orbits that converge near pericenter, resulting in extreme vertical compression to scales $10^{-4}~R_\odot$ and the formation of a nozzle shock. Dissipation at the nozzle shock may affect circularization by altering the properties of the debris stream, but its role is the subject of ongoing debate. We develop an idealized model for the debris stream evolution combining 3D smoothed-particle hydrodynamics simulations, the semi-analytic affine model, and 1D finite-volume hydrodynamic simulations. Because our model is computationally cheap, we can unambiguously resolve the nozzle shock, use a realistic equation of state, and follow the debris stream evolution at many different times. Near peak fallback, Hydrogen recombination and molecular Hydrogen formation broaden the stream by a factor $\sim 5$, enhancing dissipation at the nozzle. However, the dissipation is still insufficient to directly circularize the debris by in-plane pressure gradients. Instead, the thicker stream substantially increases the likelihood that the stream self-intersects on the second orbit, despite RELATIVISTIC nodal precession. The stream properties at self-intersection are sensitive to dissipation at the nozzle and the timing of focal points where the ballistic trajectories of the debris converge. Our results clarify the nozzle shock's role in circularization in TDEs, providing a foundation for more realistic circularization and emission models.
[abstract 12 / 53] Yes (score: 4) - Title: Gamma-Ray Bursts: Evidence for a Common Origin of X-ray Plateaus with Diverse Temporal Decay IndexAuthors: Xiao-Fei Dong, Yong-Feng Huang, Chen Deng, Ze-Cheng Zou, Jin-Jun Geng, Fan Xu, Chen-Ran Hu, Orkash Amat, Xiu-Juan Li, Liang Li, Abdusattar Kurban,Comments: 10 pages, 9 figures, 3 tables, published in ApJSubjects: astro-ph.HECreated: 2026-06-01; Updated: 2026-06-02; Datestamp: 2026-06-02
A significant fraction of GAMMA-RAY BURSTs (GRBs) exhibit a plateau in the early X-ray afterglow light curve, whose mechanism remains uncertain. While the post-plateau normal decay index ($α_2$) is commonly used to constrain the afterglow dynamics, the shallow-decay slope of the plateau itself ($α_1$) has received comparatively little attention. Recent observations, however, reveal substantial dispersion in $α_1$, raising the question of whether GRBs with rising, flat and mildly decaying plateaus represent intrinsically distinct populations. To address this question, we collect a uniform sample of 185 $\textit{SWIFT}$ GRBs with a well-defined plateau and divide them into three groups based on $α_1$. Using a non-parametric approach, we reconstruct their X-ray luminosity functions, redshift distributions and event rates. It is found that the three groups exhibit statistically consistent properties across all diagnostics, with no evidence for group-specific features. Monte Carlo perturbation tests further show that these results are insensitive to the adopted classification boundaries of $α_1$. Our results indicate that variations in the plateau slope $α_1$ do not define distinct GRB subclasses, but instead the sample constitutes a statistically uniform population governed by a common framework.
[abstract 13 / 53] Yes (score: 4) - Title: On the Faint Early-time Radio and X-ray Emissions in TDE2025aarmAuthors: Tatsuya Matsumoto, Tsvi Piran,Comments: 7 pages, 4 figures, submitted to ApJL, comments welcome!!!Subjects: astro-ph.HECreated: 2026-05-29; Updated: 2026-06-02; Datestamp: 2026-06-02
TDE2025aarm is a nearby tidal disruption event whose early radio and X-ray emissions are exceptionally faint compared with previously observed TDEs. We examine whether these weak signals can be explained within standard outflow and disk-emission scenarios. The radio detection at $15\,\rm GHz$ with $\sim10^{36}\,\rm erg\,s^{-1}$ around $40\,\rm days$ after discovery is inconsistent with SYNCHROTRON emission from a quasi-spherical disk wind for reasonable circum-nuclear densities and outflow velocities. Instead, the low luminosity and inferred self-absorbed spectrum imply a narrowly collimated outflow with a solid angle $\lesssim0.1\,\rm sr$, naturally identified with the unbound stellar debris. The X-ray emission is likewise unusually faint, with $L_{\rm X}\sim10^{39-40}\,\rm erg\,s^{-1}$ during the first few months. If interpreted as thermal emission from an obscured accretion disk, the inferred emitting area would correspond to an implausibly small X-ray-transparent region expected to vary on short dynamical timescales that are not observed. Alternatively, the same shock responsible for the radio emission can accelerate RELATIVISTIC electrons that produce X-rays through SYNCHROTRON radiation and/or inverse-Compton scattering of optical/UV photons. Both mechanisms can explain the early faint X-ray emission, although their temporal evolution differs. Continued radio and X-ray monitoring of TDE2025aarm will provide a sensitive probe of the unbound debris, circum-nuclear medium, and high-energy emission mechanisms in optical TDEs.
[abstract 14 / 53] Yes (score: 4) - Title: Prospects of resolving and localising individual supermassive BLACK HOLE binaries with pulsar timing arrays: the host ranking challengeAuthors: Niccolò Veronesi, Maria Charisi, Polina Petrov, Stephen R. Taylor, Jessie Runnoe, Daniel J. D'Orazio, Jacob Pilawa, Chung-Pei Ma,Comments: 18 pages, 9 figuresSubjects: astro-ph.GA astro-ph.HECreated: 2026-05-29; Updated: 2026-06-02; Datestamp: 2026-06-02
Pulsar Timing Arrays (PTAs) are soon expected to detect individually resolved supermassive BLACK HOLE (SMBH) binaries, opening the possibility for multi-messenger discoveries. The biggest challenge will be to pinpoint the host galaxy in a large localisation area. We simulate realistic binary populations consistent with the gravitational wave (GW) background, projecting the PTA sensitivity for the next 0-10 years. We inject the loudest binary on top of the background and use one of the standard detection pipelines to constrain its properties. We cross-match the localisation areas with comprehensive all-sky galaxy catalogues and estimate the number of candidate hosts in the localisation area assessing, for the first time, the number of missing galaxies due to incomplete coverage. We develop a ranking system that excludes galaxies with properties inconsistent with the GW posteriors, and prioritizes the remaining galaxies for follow-up observations. We find a $\approx$21, $\approx$38 and $\approx$51 percent probability of resolving a binary in the next 0, 5 and 10 years, respectively, reduced to 0.3, 3.8 and 14.1 percent if we require potentially well-constrained localisation areas. The localisation areas span hundreds of square degrees, but shrink significantly with the addition of more data. They contain on average $\approx$190,000 early type galaxies and $\approx$40,000 ACTIVE GALACTIC NUCLEi, with $\approx$25,000 missing candidate hosts. Our ranking method can exclude about half of the potential hosts and efficiently rank those remaining when the galaxy catalogue provides SMBH masses and redshifts, but becomes more inefficient when we rely on apparent magnitudes.
[abstract 15 / 53] Yes (score: 4) - Title: Reconnection-Driven Injection and Stochastic Reacceleration during Cosmological MagnetogenesisAuthors: Ji-Hoon Ha,Comments: 10 pages, 5 figuresSubjects: astro-ph.HE astro-ph.COCreated: 2026-06-01; Updated: 2026-06-02; Datestamp: 2026-06-02
We investigate whether MAGNETic RECONNECTion can provide suprathermal proton seed particles during cosmological MAGNETogenesis prior to nonlinear structure formation. Previous work showed that pressure-anisotropy-driven stochastic acceleration alone is strongly limited by cosmological expansion and Coulomb cooling. Here, we extend this framework by adding a phenomenological RECONNECTion-driven source term to the Fokker--Planck equation for the isotropic ion distribution, with the injection power tied to the MAGNETic-energy growth rate during MAGNETogenesis. We find that RECONNECTion can act as a fast injection channel and can produce a visible suprathermal tail. However, the resulting nonthermal energy fraction remains very small, of order $10^{-7}$ in the fiducial model, implying a negligible nonthermal pressure contribution to the pre-structure intergalactic medium. This limitation arises because the extremely high-beta plasma contains only a small MAGNETic-energy reservoir, even when RECONNECTion itself is locally fast. Using a test-particle shock reacceleration estimate, we further show that the RECONNECTion-produced tail can enhance the suprathermal proton population available for later structure-formation shocks by about an order of magnitude. Nevertheless, the associated hadronic gamma-ray emission from low-density cluster outskirts is expected to remain far below current detectability. We therefore conclude that RECONNECTion during cosmological MAGNETogenesis is unlikely to dominate the cosmic-ray energy budget directly, but may provide a low-level seed population for subsequent shock acceleration.
[abstract 16 / 53] (score: 3) - Title: The role of the galaxy stellar mass function in determining the cosmological distribution of astrophysical transients with applications to fast radio bursts and merging binary BLACK HOLEsAuthors: Sandeep Kumar Acharya,Comments: Comments welcome. Accepted in JCAPSubjects: astro-ph.HE astro-ph.CO astro-ph.GACreated: 2026-06-01; Updated: 2026-06-02; Datestamp: 2026-06-02
The cosmological distribution and formation rate of compact astrophysical objects such as fast radio bursts (FRBs) are typically assumed to be proportional to a linear combination of cosmological STAR FORMATION rate and stellar mass. In the literature, a template for STAR FORMATION rate, which is just a function of redshift, is typically used. In this work, we point out the importance of galaxy stellar mass function which captures the host galaxy information of observed FRBs as well as the redshift evolution of galaxy stellar mass. Using this information and taking the stellar mass distribution of a sample of localized FRBs at face value, we find that FRB formation efficiency per stellar mass may have to be more efficient (by a factor of $\approx 3$) than previously calculated, in order to reproduce the observed volumetric rate of FRBs at $z=0$. We show that cosmological population studies of FRBs have to include host galaxy information along with its redshift evolution in order to obtain unbiased results. This consideration is also applicable to other transients, e.g. GAMMA-RAY BURSTs and merging binary BLACK HOLE events. We show that our approach may open up the possibility to distinguish between different scenarios of merging binary BLACK HOLEs formation with a detection of few thousand gravitational wave events.
[abstract 17 / 53] (score: 3) - Title: BBH-Genesis: Disentangling Binary Black Hole Formation Channels with GWTC-4Authors: Shaunak Padhyegurjar, Suvodip Mukherjee,Comments: Comments are welcome!Subjects: astro-ph.HE astro-ph.CO gr-qcCreated: 2026-05-29; Updated: 2026-06-02; Datestamp: 2026-06-02
The detected population of binary BLACK HOLEs (BBHs) from the gravitational wave (GW) data has made it possible to decipher their formation and evolution history over cosmic time. The complexity of astrophysical modeling of binary mergers makes it challenging to predict key signatures for different formation channels. As a result, one of the major avenues to discover the presence of different channels from detected GW events is through a data-driven way which can isolate different scenarios. In this spirit, we developed a new inference pipeline BBH-Genesis and applied it on the fourth GW catalog (GWTC-4) to identify the presence of multiple underlying distinct populations. We find that the current population of all the binary events in GWTC-4 can be explained with the strongest evidence for only a two-channel scenario, hinting at the presence of a non-isolated binary formation channel. This sub-population can be further divided into a third channel with mild support towards formation in AGN exhibiting a slightly different effective spin and mass ratio correlation. In the future, with the detection of more events, it will be clearer whether it is necessary to consider at least three channels to explain the BBH events detected using GW observations.
[abstract 18 / 53] (score: 3) - Title: The Delta Resonance in the Neutrino SkyAuthors: Arifa Khatee Zathul, Ke Fang, Francis Halzen, Dan Hooper,Comments:Subjects: astro-ph.HE hep-phCreated: 2026-05-29; Updated: 2026-06-02; Datestamp: 2026-06-02
Recent measurements of the diffuse cosmic neutrino flux by IceCube show evidence for a spectral break at an energy near $E_ν\sim 30$ TeV. In this letter, we suggest that this feature may be due to the $Δ$-baryon resonance in $pγ$ interactions. We show that the measured spectrum, including the observed break, can be naturally accommodated by a flux of protons accelerated with a spectrum $dN_p /dE_p \propto E_p^{-3.1}$ interacting with X-rays of typical energy $E_γ \sim 0.3\,{\rm keV}$. We also point out that the presence of this spectral break significantly reduces the contribution of neutrino sources to the isotropic gamma-ray background, alleviating the longstanding tension between these measurements. In the $Δ$-resonance scenario, the gamma rays accompanying neutrino production cascade down to MeV-GeV energies and contribute at the $\sim 10\%$ level to the isotropic gamma-ray background at $\sim 3$~GeV. If our proposal is realized, it may imply that we have identified the dominant sources that produce the extragalactic COSMIC RAYs.
[abstract 19 / 53] (score: 3) - Title: Lattice Boltzmann Methods for Compressible (Magneto)hydrodynamicsAuthors: Fedor Bukreev, Adrian Kummerländer, Mathias J. Krause,Comments:Subjects: physics.flu-dyn physics.comp-ph physics.plasm-phCreated: 2026-05-30; Updated: 2026-06-02; Datestamp: 2026-06-02
The simulation of MAGNETohydrodynamic (MHD) flows presents a highly complex, tightly coupled transport problem that poses severe numerical and computational demands. Towards this, we propose a novel class of Lattice Boltzmann Methods (LBM) schemes capable of solving a wide range of transport equation systems with high computational efficiency and scalability. Our approach exploits the algorithmic structure of kinetic formulations to separately transport all state variables of Strang-splitted conservation equations alongside their characteristics, yielding decoupled, fully local operations. To demonstrate the capability of this framework on complex, numerically demanding multiphysics interactions, we apply it to these MHD flows. Specifically, we discretize ideal compressible and resistive incompressible MHD systems, which naturally encompass hydrodynamic limits such as the compressible Euler and incompressible Navier-Stokes equations. Rigorous performance analysis of the implementation within the platform-transparent multi-physics framework OpenLB demonstrates up to 98.9\% of the hardware roofline. We validate our approach against established incompressible and compressible MHD benchmarks across multiple resolutions. Finally, we simulate a moving, surface-resolved MAGNETized asteroid modeled after 16 Psyche in a supersonic early solar wind flow. This showcases the framework's advanced support for dynamic solid geometries, shifting MAGNETic fields, and fluid-structure interaction.
[abstract 20 / 53] (score: 3) - Title: The COSMIC RAY ionization rate from H3+ observations can be overestimated due to neglect of time-dependent chemistryAuthors: Ka Wai Ho, Munan Gong, Kedron Silsbee, Alexei Ivlev,Comments: 11 pages, 6 figuresSubjects: astro-ph.GACreated: 2026-05-30; Updated: 2026-06-02; Datestamp: 2026-06-02
The COSMIC RAY ionization rate (CRIR) is a key parameter governing the physical, chemical and thermal evolution of the interstellar medium. The primary technique for measuring the CRIR in diffuse molecular clouds relies on observations of ${\rm H_3^+}$. Previous analyses of these observations have derived the CRIR under the assumption of steady-state chemistry. Here, we investigate the effect of time-dependent chemistry on the inferred CRIR from ${\rm H_3^+}$ observations. We perform 3D MHD simulations with coupled chemistry and driven turbulence. Following procedures similar to those used in the literature to analyze ${\rm H_3^+}$ observations, we conduct mock CRIR measurements by post-processing our simulations with different values of the CRIR to obtain steady-state abundances of ${\rm H_2}$ and ${\rm H_3^+}$. By comparing those with the abundances from time-dependent chemistry, we determine the best-fitting value of the CRIR. We find that the abundances of both ${\rm H_2}$ and ${\rm H_3^+}$ are higher in time-dependent chemistry simulations than in the steady-state case, especially in low-density regions. Furthermore, the inferred CRIR under the steady-state assumption is a factor of $\sim 2-5$ higher than the true CRIR, with a median value of $ζ_\mathrm{inferred}/ζ_\mathrm{true} \approx 3$. This bias increases with stronger MAGNETic fields, weaker FUV radiation fields, and stronger turbulence. Accounting for time-dependent chemistry, we report an average CRIR per ${\rm H_2}$ of $ζ_{H_2} = 2\times 10^{-17}~\mathrm{s^{-1}}$ from the ${\rm H_3^+}$ observations. The CRIR is consistent with a constant value over the column density range of $N=(2-6)\times10^{21}~\mathrm{cm^{-2}}$.
[abstract 21 / 53] (score: 3) - Title: Cellular Sheaf Neural Operators for Structure-Preserving Surrogate Modeling of Constrained PDEsAuthors: Lennon J. Shikhman, Shane Gilbertie,Comments: 41 pages, 5 figures, 3 tablesSubjects: cs.LG cs.CE cs.NA math.NA physics.comp-ph physics.plasm-phCreated: 2026-05-31; Updated: 2026-06-02; Datestamp: 2026-06-02
Neural operators provide fast surrogate models for PDE simulations, but standard architectures often treat geometry and discretization as secondary to field data. Physical states are usually represented as grid-channel stacks, even when different quantities naturally belong on vertices, edges, faces, cells, boundaries, or interfaces and must satisfy compatibility constraints. We propose Cellular Sheaf Neural Operators, a discretization-aware framework for structure-preserving neural PDE surrogates. The method represents PDE states on oriented cell complexes, couples local feature spaces through learned restriction maps, and uses incidence/Hodge-informed message passing to follow computational geometry. Learned update heads pass through coboundary or flux maps, allowing selected constraints to arise from cell-complex structure rather than only from loss penalties. For MAGNETohydrodynamics, this yields face-based MAGNETic-flux updates driven by edge electromotive fields and finite-volume-style fluid updates driven by learned face fluxes and cell sources. On turbulent MHD and fusion-equilibrium surrogate tasks, the method improves structure-sensitive diagnostics, including rollout behavior, divergence control, spectral error, and equilibrium-regression accuracy. These results indicate that cellular-sheaf structure is a useful inductive bias for neural PDE surrogates in constrained multiphysics systems.
[abstract 22 / 53] (score: 3) - Title: Understanding the Broad-line Region of Active Galactic Nuclei with Photoionization. II. Slim disks, Self-shadowing, and BLR sizesAuthors: Qiaoya Wu, Yue Shen, Chris Done, Michael R. Goad, Scott Hagen,Comments: 19 pages, 13 figures. Submitted to ApJ. Comments welcome!Subjects: astro-ph.GACreated: 2026-05-31; Updated: 2026-06-02; Datestamp: 2026-06-02
Reverberation-mapping (RM) measurements have revealed that high-accretion-rate ACTIVE GALACTIC NUCLEi (AGNs) systematically lie below the canonical broad-line region (BLR) radius - optical continuum luminosity (R-L) relation, exhibiting shorter lags than predicted for fixed 5100Åluminosity. The physical origin of these offsets remains debated. We investigate how accretion-flow structure and BLR cloud properties affect the emissivity-weighted BLR radius using analytic slim-disk SEDs and photoionization calculations on a two-dimensional axisymmetric grid. As the accretion rate approaches and exceeds the Eddington limit, geometric thickening of the inner disk produces anisotropic illumination and self-shadowing, reducing ionizing flux seen by low-latitude BLR clouds and flattening the R-L relation at high L/LEdd. Self-shadowing at high accretion rates reproduces the observed R-L trend in the RM AGN sample reasonably well, but this effect alone is insufficient to explain the observed lag offset in low-mass ($\sim10^{7}M_\odot$) systems with high accretion rates. Motivated by accretion-disk density scalings, we further explore models in which the BLR gas density increases toward lower BLACK HOLE mass or higher accretion rate. We find that an accretion-rate-dependent BLR density enhancement further improves agreement with observed RM data, where the BLR gas density increases by a factor of 3-5 for one dex increase in $\dot{m}$. Variations in BLR opening angles produce a less important effect on BLR sizes. These results demonstrate that self-consistent modeling of accretion disk SED, BLR illumination and photoionization, and gas density variations can fully explain the observed distribution of AGNs in the BLR size - optical luminosity plane. This framework provides a physically motivated link between accretion-flow structure and BLR observables across a broad range of black-hole properties.
[abstract 23 / 53] (score: 3) - Title: The Information Content of Quasar Variability Light Curves: How Well Can we Infer Stochastic Model Parameters?Authors: Brendon J. Brewer, Geraint F. Lewis, Xiang Yu, Yuan Li,Comments: Submitted. 17 pages, 7 figures, 3 tablesSubjects: astro-ph.GA physics.data-an stat.APCreated: 2026-05-31; Updated: 2026-06-02; Datestamp: 2026-06-02
Quasar variability, driven by multi-scale physical processing within a RELATIVISTIC accretion disk, is commonly modelled with stochastic time series models. The simplest of these is the Damped Random Walk (DRW), also known as the Ornstein-Uhlenbeck (OU) process. Here, we demonstrate that, when fitting such a model to QUASAR light curve data, the mean of the light curve, $μ$, should not be fixed (which is the typical approach), as this leads to overconfident inferences about the variability timescale $τ$, with substantially underestimated uncertainties. However, the short term volatility parameter $η$ is typically very well constrained from short light curves. Through simulations, we compute information theoretic quantities such as the conditional entropy and the mutual information, confirming that light curves provide much more information about $η$ than about $τ$. As a result, we recommend that future QUASAR variability studies focus on $η$ rather than $τ$. To demonstrate this approach, we fit a hierarchical Bayesian regression model for $η$ as a function of bolometric luminosity and rest wavelength to a dataset of 570 light curves measured over decades. We perform the fit using a likelihood function that uses the light curves directly, rather than using intermediate $η$ values from individual light curve fits. We find that volatility decreases as a function of both bolometric luminosity and rest wavelength. The volatility also decreases more steeply with redshift than time dilation alone would suggest, pointing to an increase in intrinsic volatility as QUASARs evolve over cosmic time.
[abstract 24 / 53] (score: 3) - Title: A new Chandra look at the globular cluster NGC 6540 and its peculiar X-ray flaring sourceAuthors: A. Sacchi, S. Mereghetti, R. Di Stefano, J. A. Irwin, M. Rigoselli, A. De Luca, N. Sims,Comments: 6 pages, 4 figures, 2 tables. Submitted to A&A, comments are welcomeSubjects: astro-ph.HECreated: 2026-06-01; Updated: 2026-06-02; Datestamp: 2026-06-02
We report the results of a deep ($\approx65$ ks) Chandra observation of the globular cluster NGC 6540, obtained to investigate the nature of the peculiar X-ray source 3XMM J180608.9$-$274553. This source was previously observed with XMM$-$Newton to exhibit a short ($\approx300$ s) and intense X-ray flare whose luminosity and duration are inconsistent with both typical type I X-ray bursts from low mass X-ray binaries and stellar flares. Our new data show the presence of three faint X-ray sources near the position of the flare seen by XMM$-$Newton, only one of which was detected in a previous, much shorter Chandra observation. Based on the properties of these sources, localized at sub-arcsecond precision, and of their optical counterparts, we discuss their possible nature and association with 3XMM J180608.9$-$274553. We also discuss some scenarios to explain the X-ray flare, such as microlensing-induced amplification, BLACK HOLE flaring activity analogous to that observed from Sgr A$^\ast$. Our results place new constraints on the nature of this unusual transient and highlight the power of high-resolution X-ray observations for disentangling rare phenomena in the dense stellar environments of globular clusters.
[abstract 25 / 53] (score: 3) - Title: Fast radio bursts, MAGNETars and earthquakes: their "family feud"?Authors: Si-Lu Xu, Yong-Kun Zhang, Pei Wang, Di Li, Jun-Shuo Zhang, Tian-Cheng Lv, Yong-Feng Huang, Tian-Cong Wang, Long-Xuan Zhang, Pei-Xin Zhu, Jin-Huang Cao, Yi Feng, He Gao, Jian Li, Wan-Jin Lu, Chen-Chen Miao, Chen-Hui Niu, Qing-Yue Qu, Chao-Wei Tsai, Yi-Dan Wang, Wen-Ting Wang, Su-Ming Weng, Jia-Fu Wu, Ru-Shuang Zhao, Yuan-Chuan Zou, Yu-Hao Zhu, Ya-Biao Wang,Comments: 12 pages, 3 figures, accepted for publication in Science China Physics, Mechanics & AstronomySubjects: astro-ph.HECreated: 2026-06-01; Updated: 2026-06-02; Datestamp: 2026-06-02
Fast radio bursts (FRBs) are millisecond-duration cosmic transients whose origin remains elusive. Competing models invoke either earthquake-like processes or flare-like mechanisms. To discriminate between these scenarios, we develop a novel diagnostic, the Pincus-Lyapunov diagram (PLD), to characterize the energetic transients in the stochasticity-chaos phase space. We compile burst sequences from five representative FRBs (FRB 20121102A, FRB 20190520B, FRB 20201124A, FRB 20220912A, and FRB 20240114A), together with those from MAGNETar flares (SGR J1550$-$5418, SGR J0501+4516, SGR 1806$-$20, SGR 1900+14, and SGR J1935+2154), pulsar glitches, solar flares, and earthquakes, and map them onto the PLD for comparative analysis. The resulting diagram shows that FRBs occupy a distinct region of the phase space. Specifically, a permutation test reveals a statistically significant difference in the distributions of MAGNETar flares and pulsar glitches compared to those of repeating FRBs ($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 26 / 53] (score: 3) - Title: Radio Continuum Emission from Evolving Star-Forming Galaxies -- I. Correlations Involving the Total Synchrotron LuminosityAuthors: Sukanta Ghosh, Luke Chamandy, Charles Jose, Anvar Shukurov, Luiz Felippe S. Rodrigues, Fatemeh Tabatabaei,Comments: Main text 35 pages, 30 figures, and 8 tables. Submitted to ApJ. Comments welcome!Subjects: astro-ph.GACreated: 2026-06-01; Updated: 2026-06-02; Datestamp: 2026-06-02
Synchrotron radiation dominates the continuum emission of star-forming galaxies in the frequency range from a few $\rm MHz$ to about $30\,\rm{GHz}$. We model the total SYNCHROTRON emission of a large population of evolving star-forming galaxies using the semi-analytic galaxy formation model GALFORM combined with the dynamo simulation code MAGNETIZER. Assuming local energy equipartition between COSMIC RAYs and MAGNETic fields, we calculate the specific SYNCHROTRON luminosity $L_ν$ for each simulated galaxy at various frequencies and find strong positive correlations between $L_ν$ and both the STAR FORMATION rate ($\rm SFR$) and characteristic galaxy rotation speed $V_{\rm rot}$ for redshifts up to $z\simeq 3$. At low redshifts, the turbulent MAGNETic field is found to dominate in the SYNCHROTRON luminosity, but the contribution of the large-scale MAGNETic field increases with redshift and becomes important for $z\gtrsim 1$. The correlation between $L_ν$ and $\rm SFR$ arises from the tight correlation between the disc gas mass $M_{\rm gas}$ and $\rm SFR$, and the correlation between $L_ν$ and $V_{\rm rot}$ is additionally a consequence of the stellar mass Tully--Fisher relation for main-sequence galaxies. At low redshifts, the model predictions and observational data compiled for this work show remarkable agreement, but a discrepancy arises at higher redshifts, where modelled $\rm SFR$ values are systematically smaller than those previously inferred from observations. These theoretical models will aid the interpretation of next-generation radio surveys with the Square Kilometre Array and other telescopes.
[abstract 27 / 53] (score: 2) - Title: Self-lensing of moving gravitational-wave sources can break the microlensing crossing timescale degeneracyAuthors: Helena Ubach,Comments: 15 pages, 9 figures; (v2) Submitted version (v3) Substantial update; Comments welcomeSubjects: astro-ph.HE astro-ph.CO astro-ph.GACreated: 2026-06-01; Updated: 2026-06-02; Datestamp: 2026-06-02
When a moving gravitational-wave (GW) source travels behind a massive astrophysical object, its signal is gravitationally lensed, showing a waveform distortion similar to a Paczyński curve. We present a first study on the lensing signature of a massive BLACK HOLE (MBH) on a frequency-dependent GW signal from a moving compact binary merger (CBC) source, focused on ground-based GW detectors. For both light and GW sources in a Keplerian circular orbit around a MBH lens, the self-lensing geometry breaks the microlensing degeneracy in the Einstein radius crossing timescale $t_{\rm E}$. The duration of the curve ($2 t_{\rm E}$) becomes independent on the MBH mass $M_{\rm MBH}$, and provides a direct value of the orbital distance $d_{\rm LS}$ of the source around the MBH. However, $M_{\rm MBH}$ remains unknown. In GW signals, the redshifted mass $M_{{\rm MBH},z}$ can additionally be analytically inferred from the interference pattern, once the modulation period $T$, the GW frequency $f$, and $t_{\rm E}$ are known: $M_{{\rm MBH},z}\simeq 2.5\times 10^6\,M_\odot\,(t_{\rm E}/[100\,{\rm s}])\,(f\,T)^{-1}$. If this lensing signature is not considered, it may be confused with other waveform distortions, especially in the modeling of overlapping CBC signals in next generation ground-based GW detectors. The observation of one of these curves and its associated parameters may help (1) constrain the orbital distance $d_{\rm LS}$ of sources, especially around low-mass MBHs at the center of star clusters and galaxies, (2) additionally estimate the mass $M_{{\rm MBH},z}$ of these MBHs, and (3) infer the orbital inclination of the binary. Simultaneously obtaining $d_{\rm LS}$ and $M_{{\rm MBH},z}$ through self-lensing can help constrain the astrophysical environments where GW signals come from.
[abstract 28 / 53] (score: 2) - Title: Inference of Neutron Star Mass Distributions and the Dense Matter Equation of State from Multi-messenger ObservationsAuthors: Mahmudul Hasan Anik, Andrew W. Steiner, Richard O'Shaughnessy,Comments: Accepted by the Astrophysical Journal; contains 18 pages, 6 figures, 6 tablesSubjects: astro-ph.HECreated: 2026-05-30; Updated: 2026-06-02; Datestamp: 2026-06-02
We construct a combined model to incorporate neutron star (NS) mass measurements with electroMAGNETic mass-radius constraints and gravitational-wave observations using Bayesian inference. We use different mass distributions for three populations depending on the companion stars: double neutron stars, NS - white dwarfs, and low-mass X-ray binaries (LMXB). To observe the effects of different parametrizations, we use two equation of state (EoS) models: a piecewise polytrope and a fixed sound-speed model at high densities in combination with a low-density EoS. Our results show that the mass distributions of these NS populations are distinct and sensitive to the EoS prior choices. In addition, we show for the first time that using a uniform prior on the observable NS maximum mass, rather than a nuisance parameter in the unknown high-density EoS, shifts the posterior maximum mass to larger values. For polytropic EoSs, the maximum mass posterior changes from $M_\mathrm{max}=2.09_{-0.07}^{+0.18} M_\odot$ to $2.15_{-0.10}^{+0.19} M_\odot$ at 90% confidence level. This change in prior also impacts the shape of the mass distribution for NSs in LMXB, shifting the posterior for the population mean from $μ_\mathrm{lmxb} = 1.51_{-0.13}^{+0.13} M_\odot$ to $1.62_{-0.12}^{+0.15} M_\odot$ at 68% confidence level.
[abstract 29 / 53] (score: 2) - Title: Radiation-hydrodynamics of star-disc collisions for quasi-periodic eruptionsAuthors: Taj Jankovič, Clément Bonnerot, Sergey Karpov, Aleksej Jurca,Comments: Accepted for publication in A&ASubjects: astro-ph.HECreated: 2026-06-01; Updated: 2026-06-02; Datestamp: 2026-06-02
Quasi-periodic eruptions (QPEs) are recently discovered transients of unknown nature occurring near supermassive BLACK HOLEs, which feature bright X-ray bursts separated by hours to days. A promising model for QPEs is the star-disc collisions model, where a star repeatedly interacts with an accretion disc around a BLACK HOLE, creating shocks that expel dense outflows of gas from which radiation emerges. We investigate the dynamics of the star-disc collisions, the properties of the outflows, and the resulting radiation signatures. Our study focuses on the generic case where the star remains unperturbed by the collision and the stellar crossing time through the disc is sufficiently long for shocked gas to flow around the star. We performed a three-dimensional (3D) radiation-hydrodynamics simulation of the star-disc collision. The star was modeled as a solid, spherical body, and the interaction was simulated for a small, local section of the accretion disc. We found that star-disc collisions generate a nearly paraboloidal bow shock. The heating of gas is not confined to the column of gas directly ahead of the star but also extends laterally as the shock front expands sideways while traveling with the star. As the star crosses the disc, it injects momentum preferentially along its direction of motion, leading to an asymmetric redistribution of energy and momentum. As a result, two outflows emerge on opposite sides of the disc with different properties: the forward outflow expands faster, contains more mass, carries more energy, and is about twice as luminous as the backward outflow. Our findings suggest that the asymmetry in outflow properties and luminosity arises naturally from the collision dynamics, offering a possible explanation for the alternating strong-weak flare patterns observed in several QPE sources.
[abstract 30 / 53] (score: 2) - Title: Spacetime of rotating BLACK HOLEs surrounded by massive scalar chargesAuthors: Adrian Ka-Wai Chung,Comments: 21 pages of main text, 13 figures; Match the published version; Data product available at https://zenodo.org/records/20022233Subjects: gr-qcCreated: 2026-05-31; Updated: 2026-06-02; Datestamp: 2026-06-02
Massive scalar charges are ubiquitous in extensions to General Relativity and the Standard Model in particle physics. We describe spectral methods which can accurately construct the spacetime of rotating BLACK HOLEs with dimensionless spin up to $a \leq 0.8$ surrounded by massive scalar fields nonminimally coupled to spacetime curvature. We consider axi dilaton, dynamical Chern Simons, and scalar Gauss Bonnet couplings, and obtain leading order solutions for both the scalar field and the associated metric modifications. Our method accurately resolves massive scalar fields with Compton wavelengths as short as 5 times the BLACK HOLE mass, achieving residual errors $\lesssim 10^{-5}$, and yields the corresponding leading order spacetime modifications with residual errors $\lesssim 10^{-3}$. Using the constructed spacetimes, we computes the leading-order shifts in the surface gravity and the angular velocity of the event horizon, important information for computing the quasinormal modes. These results pave the way to incorporate massive scalar charges into electroMAGNETic observations and gravitational-wave detections of BLACK HOLEs, potentially enabling new probes of fundamental scalar degrees of freedom.
[abstract 31 / 53] (score: 2) - Title: New Dynamical Measurements from a Lensed Quasar Sample: Joint Analysis Constrains the Mass Profile Evolution of Lens GalaxiesAuthors: Ziyu Guo, Yun Chen, Yiping Shu, Jiaze Gao, Hui Li, Zizhao He, Jun Wang,Comments: 14 pages, 5 figures; Accepted for publication in MNRASSubjects: astro-ph.GACreated: 2026-05-29; Updated: 2026-06-02; Datestamp: 2026-06-02
We present a systematic study of the internal mass structure of early-type galaxies (ETGs) based on 106 galaxy-scale strong gravitational lenses with background QUASARs, all having spectroscopic redshifts. From this parent sample, we select 24 systems with high-quality ancillary data for joint analysis of strong lensing geometry and stellar kinematics. A key contribution is the derivation of new single-aperture stellar velocity dispersions for 11 lens galaxies via an iterative spectroscopic fitting procedure that mitigates QUASAR contamination, providing previously unavailable data. We model the total mass-density profile as a power law, $ρ\propto r^{-γ}$, and parameterise its logarithmic slope as $γ= γ_0 + γ_z \cdot z_l + γ_s \cdot \log \tildeΣ$, where $z_l$ is the lens redshift and $\tildeΣ$ the surface mass density. Within a flat $Λ$CDM framework and using DESI BAO measurements as a prior, we constrain the parameters via Monte Carlo nested sampling to $γ_0 = 1.62^{+0.11}_{-0.12}$, $γ_z = -0.35^{+0.08}_{-0.09}$, and $γ_s = 0.37^{+0.08}_{-0.07}$ ($68\%$ confidence intervals). Our results robustly demonstrate that $γ$ increases with surface mass density ($γ_s > 0$) and decreases with redshift ($γ_z < 0$). This implies that, at fixed redshift, galaxies with denser stellar cores have steeper mass profiles, while at fixed density, profiles become shallower at higher redshifts. By successfully applying the joint lensing--dynamics method to a substantial, independently acquired sample of lensed QUASARs, this work provides crucial validation of structural trends previously observed in galaxy--galaxy lensing systems, reinforcing the established evolutionary picture for massive ETGs and establishing lensed QUASARs as a potent probe of galaxy structure.
[abstract 32 / 53] (score: 2) - Title: The impact of the formation channel on gravitational-wave-galaxy cross-correlationsAuthors: Kabir Chakravarti, Federico R. Urban,Comments: Matches the version published in the Open Journal of AstrophysicsSubjects: astro-ph.COCreated: 2026-06-01; Updated: 2026-06-02; Datestamp: 2026-06-02
The angular, harmonic cross-correlation between gravitational wave (GW) events and galaxy catalogues contains rich information on the large-scale structure and the origin of compact binary mergers. In this work, we study how uncertainties in the binary formation channel affect the predicted cross-correlation signal for both current-generation and next-generation networks of detectors. We generate five mock GW catalogues for which we vary the progenitor-to-remnant mass-transfer function and the time-delay probability distribution between progenitor and remnant. We then cross-correlate these catalogues with galaxy samples modelled on the 2MASS Photometric Redshift catalogue (2MPZ) and the Gaia-unWISE QUASAR catalogue (Quaia). We find that the mass-transfer function has negligible effect on the cross-correlation signal, with differences remaining within redshift uncertainties. In contrast, the time-delay distribution dramatically affects the redshift distribution of the GW events and, with it, the cross-correlation signal, particularly for shallow galaxy catalogues. In particular, current-generation facilities can achieve significant detections only for the longest time delays when cross-correlated with 2MPZ, whilst all cross-correlations with the deeper Quaia catalogue are marginally detectable or consistent with zero. Our exploratory results thus demonstrate that forecasts on cosmological or astrophysical parameters derived from GW-galaxy cross-correlations are, as expected, strongly sensitive to the assumed binary formation history.
[abstract 33 / 53] (score: 2) - Title: New BLACK HOLE mass calibrations and the fundamental plane of the broad-line region size, luminosity, and velocityAuthors: Jong-Hak Woo, Jimin Kim, Hojin Cho, Shu Wang,Comments: Published. Equations are slightly revised in this versionSubjects: astro-ph.GACreated: 2026-06-01; Updated: 2026-06-02; Datestamp: 2026-06-02
We present a new calibration of the broad-line region (BLR) size-luminosity-velocity relation using a sample of 157 AGNs with reliable Hbeta time-delay (\lag) measurements from Wang & Woo 2024. By incorporating the Eddington ratio as a third parameter, we effectively correct the systematic offset of high-Eddington AGNs in the traditional BLR size-luminosity relation. The resulting three-parameter fit defines a fundamental plane in the 3-D space of the \lag, optical luminosity, and Hbeta velocity, with an intrinsic scatter of 0.21 dex. This tight correlation reflects the coupled effects of gas kinematics, photoionization, and BLR geometry. In turn, we develop a new method to infer \lag\ from the combination of optical luminosity and Hbeta velocity, and derive single-epoch BLACK HOLE mass estimators by adopting either the full-width-at-half-maximum (FWHM) or line dispersion ($σ$) of the Hbeta line profile as the velocity indicator. The derived \lag shows a ~0.1 dex scatter, depending on the choice of calibrations. We show that the previous mass estimates based on the two-parameter size-luminosity relation with a 0.5 slope can be overestimated by up to 0.5 dex, demonstrating that the new mass estimator substantially changes the cosmic BLACK HOLE mass density and the growth of BLACK HOLE seeds in the early universe.
[abstract 34 / 53] (score: 2) - Title: Radial evolution of Alfvén wave Parametric Decay Instability in the near-Sun solar wind: Effects of Temperature AnisotropyAuthors: Hayato Saguchi, Yohei Kawazura, Munehito Shoda, Yuto Katoh,Comments:Subjects: astro-ph.SR physics.space-phCreated: 2026-06-01; Updated: 2026-06-02; Datestamp: 2026-06-02
Parametric decay instability (PDI) of Alfvén wave is thought to play an important role in the dissipation of the large-amplitude Alfvén waves and in the heating of MAGNETized plasmas. Temperature anisotropy is frequently observed by spacecraft, including Parker Solar Probe (PSP), in the near-Sun solar wind, yet its impact on PDI in the near-Sun solar wind has been understudied. We calculate the maximum growth rates of PDI, $γ_{\max}/ω_{0}$, where $ω_0$ is the frequency of the parent wave, by solving the linear dispersion relation of Chew-Goldberger-Low (CGL) equations under several expanding background models. To assess the effect of temperature anisotropy, the growth rate is compared with that derived from ideal MAGNETohydrodynamics (MHD). From $R_0$ ($ = 1.02R_\odot$) to $30R_0$, we consider three expansion cases: (i) spherically symmetric adiabatic expansion with constant wind speed, (ii) Multi-source observation- and model-constrained expansion, and (iii) a PSP-constrained profile of $(β_{\parallel},ξ)$, where $β_\parallel=8πp_{\parallel0}/B_0^2$ is the parallel plasma beta and $ξ=T_{\perp0} / T_{\parallel0}$ is the temperature anisotropy, that includes Parker-spiral effects. We find that temperature anisotropy increases $γ_{\max}/ω_{0}$ for $β\lesssim 0.1$ in the near-Sun solar wind: in the case of (iii), temperature anisotropy with $T_{\perp0} > T_{\parallel0}$ increases $γ_{\max}/ω_{0}$ by factors of $\sim 1.5$ over $R\simeq 1$--$10\,R_0$, whereas temperature anisotropy with $T_{\parallel0}>T_{\perp0}$ decreases $γ_{\max}/ω_{0}$ at larger $R$. Our results suggest that the temperature anisotropy plays an important role in the onset of PDI even in low-$β$ regimes, such as the near-Sun solar wind.
[abstract 35 / 53] (score: 2) - Title: The JET-shaped pipe morphology in planetary nebulae and core-collapse SUPERNOVA remnantsAuthors: Jessica Braudo, Noam Soker,Comments: An updated submitted versionSubjects: astro-ph.HECreated: 2026-06-01; Updated: 2026-06-02; Datestamp: 2026-06-02
We compare images of core-collapse SUPERNOVA (CCSN) remnants (CCSNRs) and JET-shaped planetary nebulae (PNe) that have a narrow, faint zone extending from side to side, termed a pipe, with a hydrodynamical numerical simulation exploding a massive star with three pairs of JETs in the framework of the jittering JETs explosion mechanism (JJEM), and conclude that JETs shaped the pipes in these CCSNRs and PNe. We present two JET-shaped PNe with a pipe and three PNe with two opposite narrow JET-shaped lobes, and argue that in some cases the two opposite narrow lobes might merge to form one long, faint zone extending from side to side of the PN, namely, a pipe. From the qualitative similarity of the pipe morphology of the two CCSNRs we analyze with the pipe of the PNe, we suggest that JETs also shaped the pipe of these CCSNRs. We strengthen this conclusion with a three-dimensional hydrodynamic simulation that reproduces two opposite narrow lobes, similar to those observed in PNe with lobes. These lobes can merge later to form a pipe. This paper is another in a series that strengthen the case for the JJEM as the primary explosion mechanism of CCSNe by comparing CCSNR morphologies with those of JET-shaped PNe.
[abstract 36 / 53] (score: 2) - Title: Cosmic Ray Feedback in Galactic Disks: Star Formation, Cosmic Ray Transport, and Multiphase Outflows in TIGRESS++ SimulationsAuthors: Chang-Goo Kim, Lucia Armillotta, Eve C. Ostriker, Sanghyuk Moon, Lachlan Lancaster, Jeong-Gyu Kim, Nora B. Linzer, Ronan N. Hix,Comments: ApJ acceptedSubjects: astro-ph.GACreated: 2026-06-01; Updated: 2026-06-02; Datestamp: 2026-06-02
We present new simulations of local star-forming disks that self-consistently evolve COSMIC RAYs (CRs) and multiphase gas using TIGRESS++. To isolate the role of CRs, we conduct paired simulations under solar-neighborhood conditions: a MAGNETohydrodynamics (MHD) model following the standard TIGRESS-classic framework with FUV heating and SUPERNOVA (SN) feedback from star clusters formed via gravitational collapse; and a CRMHD model in which an additional 10% of each SN's energy is injected as CRs. These CRs are transported anisotropically along MAGNETic field lines via a two-moment solver, with the CR scattering rate set by balancing Alfven-wave growth and damping based on the self-confinement paradigm. The CRMHD model develops a characteristic two-zone vertical CR profile: uniform pressure in the diffusion-dominated, high-density midplane gas, and an exponential atmosphere shaped primarily by advection and streaming in low-density extraplanar gas. The CR pressure is comparable to the total thermal gas pressure in the midplane, but is too uniform to affect gas dynamics, leaving SFRs unchanged. In contrast, the vertical CR pressure gradient at |z| > 1 kpc accelerates warm outflowing gas, resulting in an approximately 4 times higher mass loading factor than in the MHD model. CR-gas interactions increase CR energy near the midplane through compressional work, while CR streaming heats low-density warm-hot gas. TIGRESS++ opens a path toward investigating CR transport and CR-regulated ISM and outflow dynamics at high resolution across diverse galactic environments.
[abstract 37 / 53] (score: 2) - Title: Probing Effective Field Theory Corrections with Quasinormal Modes and Gravitational Lensing in Reissner-Nordström Black HolesAuthors: Takamasa Kanai,Comments: 19 pagesSubjects: gr-qc hep-thCreated: 2026-05-31; Updated: 2026-06-02; Datestamp: 2026-06-02
Effective field theory (EFT) provides a systematic framework for parametrizing possible higher-energy corrections to general relativity through higher-curvature interactions. In this work, we investigate gravitational lensing in both weak- and strong-field regimes for EFT-corrected Reissner-Nordström BLACK HOLE spacetimes, focusing on both weakly charged and near-extremal configurations. Using the strong deflection limit formalism, we derive the corresponding corrections to the deflection angle, photon sphere radius, critical impact parameter, and strong lensing coefficients induced by higher-derivative curvature-electroMAGNETic interactions. Our analysis is restricted to purely geometrical corrections associated with modifications of the background spacetime geometry, without including POLARIZATION-dependent corrections to the photon propagation law. We show that strong gravitational lensing observables in charged BLACK HOLE backgrounds can provide complementary probes of effective interactions between gravity and electroMAGNETic fields. These results suggest that future high-precision observations of strong lensing phenomena may place constraints on higher-curvature EFT couplings beyond general relativity.
[abstract 38 / 53] (score: 2) - Title: Suppression of boosted relic neutrinos by photon backgrounds during ultra-high-energy COSMIC RAY propagationAuthors: Gabriel Azeredo, Vitor de Souza,Comments: 14 pages, 5 figuresSubjects: astro-ph.HE hep-phCreated: 2026-05-30; Updated: 2026-06-02; Datestamp: 2026-06-02
Constraining the cosmic neutrino background (C$ν$B) represents a major experimental challenge in cosmology. Recent studies have suggested that relic neutrinos boosted by ultra-high-energy COSMIC RAYs (UHECRs) may generate observable diffuse neutrino fluxes. Previous estimates have not effectively propagated the primary COSMIC RAYs, often neglecting crucial energy losses and the unavoidable, competing interactions with diffuse photon backgrounds. Here we revisit these expectations using a realistic Monte Carlo propagation framework. This approach allows us to consistently incorporate COSMIC RAY energy losses, nuclear photodisintegration, and production of secondary neutrinos. We show that interactions with diffuse photon backgrounds strongly suppress the boosted relic neutrino flux predicted in simplified propagation scenarios. Furthermore, we demonstrate that to produce any observable suppression on the UHECR energy spectrum at Earth, or for the boosted C$ν$B component to become comparable to the cosmogenic neutrino flux, the C$ν$B density must be enhanced by a factor, the so-called overdensity, of extreme magnitude ($η\gtrsim 10^{8}$).
[abstract 39 / 53] (score: 2) - Title: Testing the cosmological principle with QUASARsAuthors: Shuangnan Chen, Xiaofeng Yang, Yunliang Ren, Xuwei Zhang, Yangjun Shi, Cheng Cheng, Xiaolong He, Sufen Guo,Comments: 7 pages, 5 figures, 2 tables, version matched the publication in Astronomy & AstrophysicsSubjects: astro-ph.COCreated: 2026-05-30; Updated: 2026-06-02; Datestamp: 2026-06-02
The inferred velocity is consistent at the 1.56 σ level with the value of 370 km/s from a purely kinematic interpretation of the CMB dipole. Based on the motion direction component analysis, we have not found any significant deviation from cosmological principle in current released QUASARs data. The cosmological principle posits that the universe is homogeneous and isotropic on the large scales. In history, the cosmological principle was confirmed by various cosmological observations from CMB to large scale structure. However, several new challenges to the cosmological principle were reported in recent years, particularly in radio observations from overdispersed radio source counts to QUASARs. Here, we firstly present studies on the peculiar velocity of large-scale anisotropy by measuring the dipole signal from the DESI DR1 catalogue with a sample of 1,176,570 QUASARs (0.8 < z < 3.0). Our analysis reveals the peculiar velocity of $|v| = 443.8 \pm 204.1$ km/s towards $(l, b) = (107.4^\circ \pm 86.8^\circ, 28.4^\circ \pm 45.2^\circ)$ in Galactic coordinates.The motion direction deviates from the CMB dipole (264.02$^\circ$, 48.253$^\circ$). The inferred velocity is consistent at the 1.56 $σ$ level with the value of 370 km/s from a purely kinematic interpretation of the CMB dipole. Based on the motion direction component analysis, we have not found any significant deviation from cosmological principle in current released QUASARs data.
[abstract 40 / 53] (score: 2) - Title: Linear causality and stability constraints on RELATIVISTIC second-order MAGNETohydrodynamicsAuthors: Yiwei Qiu, Duan She, Defu Hou,Comments: 56 pages, 10 figuresSubjects: physics.flu-dyn astro-ph.HE hep-phCreated: 2026-05-30; Updated: 2026-06-02; Datestamp: 2026-06-02
In this work, we construct a theoretical framework for RELATIVISTIC second-order MAGNETohydrodynamics based on entropy current analysis. The formalism consistently incorporates the relaxation dynamics of dissipative fluxes, ensuring the hyperbolic nature of the evolution equations. Utilizing linear mode analysis, we investigate the constraints imposed by causality and stability on this anisotropic system. By linearizing the theory around a homogeneous equilibrium state, we demonstrate that the excitation spectrum decomposes into MAGNETosonic, Alfvén, and charge-diffusion sectors. For each sector, we derive asymptotic dispersion relations in both the long-wavelength (small-$k$) and short-wavelength (large-$k$) regimes, validating them against exact numerical roots. Our numerical analysis confirms the accuracy of these asymptotic solutions and uncovers a nontrivial angular dependence, especially near special propagation directions where the ordinary momentum expansion becomes less reliable. By evaluating the large-$k$ behavior of the propagating branches alongside the damping properties of non-hydrodynamic modes, we delineate the corresponding causality constraints. We find that the admissible causal domain is governed by the interplay between anisotropic transport coefficients and relaxation times, with the resulting bounds being intrinsically mode-dependent. These findings provide a systematic theoretical foundation for developing stable and causal RELATIVISTIC MAGNETohydrodynamics beyond the first-order approximation.
[abstract 41 / 53] (score: 2) - Title: Deep Optical Follow-up Observations to IceCube Cosmic Neutrinos: a case for IC230724A with Subaru/HSC and prospects with Rubin/LSSTAuthors: Shigeo S. Kimura, Masaomi Tanaka, Seiji Toshikage, Tomoki Morokuma, Nobuhiro Shimizu, Nozomu Tominaga, Naoki Yasuda, Yousuke Utsumi, Michitoshi Yoshida, Yasushi Fukazawa, Koji S. Kawabata,Comments: 17 pages, 7 figures, 9 tablesSubjects: astro-ph.HECreated: 2026-05-31; Updated: 2026-06-02; Datestamp: 2026-06-02
IceCube has been detecting cosmic high-energy neutrinos for more than 10 years, but their major sources are still under debate. To identify them, IceCube is issuing neutrino alerts, which enable us to perform electroMAGNETic follow-up observations. In this paper, we present our Subaru/HSC deep optical follow-up observations down to 25.5 mag to a well-localized neutrino event, IceCube 230724A. We conduct a dedicated analysis with extensive evaluation of background rates and true positive rates adopting the blind analysis policy to identify or disfavor tidal disruption events (TDEs) as cosmic neutrino sources. Our analysis found no TDE candidate in the region of interest. Rubin/LSST survey will enable us to constrain their fractional contribution to the cosmic high-energy neutrino background, either $\lesssim 60\%$ or $\gtrsim30\%$ for non-detection and detection, respectively, if Rubin covers the error regions of 10 neutrino events.
[abstract 42 / 53] (score: 2) - Title: Pitching Cosmic Curveballs: Environmental Effects on Extreme-Mass-Ratio Inspirals with Spinning SecondariesAuthors: Leif Lui, Lisa V. Drummond, Alejandro Torres-Orjuela,Comments: 6 pages, 5 figuresSubjects: gr-qc astro-ph.HECreated: 2026-06-01; Updated: 2026-06-02; Datestamp: 2026-06-02
Much like the aerodynamic deflection of a spinning curveball, a rotating secondary in an extreme-mass-ratio inspiral (EMRI) experiences Magnus and lift forces, in addition to the standard drag force, when traversing a gaseous environment. We present the first framework that incorporates these specific spin-coupled environmental effects (EEs) into the evolution of EMRI. Over the multi-year observation windows of space-based gravitational-wave (GW) detectors, these interactions imprint a unique, distinguishable dephasing signature on the signal. Crucially, a Fisher matrix analysis reveals that gas drag breaks the fundamental vacuum-projection degeneracy between the secondary's spin magnitude and inclination, thereby tightening parameter constraints. Thus, accounting for EEs is not merely a modeling necessity, but a powerful tool for enhancing the detectability of the secondary's intrinsic spin, and could serve as a novel probe of accretion flows harboring massive BLACK HOLEs.
[abstract 43 / 53] (score: 2) - Title: Morphology of Optical Changing-Look AGN-host Galaxies: Evidence for an Important Role of MergersAuthors: Jie Tian, Yinghe Zhao, Jin-Ming Bai, Wei-Jian Guo,Comments: 16 pages, 5 figures, accepted by ApJSubjects: astro-ph.GACreated: 2026-06-01; Updated: 2026-06-02; Datestamp: 2026-06-02
Optical changing-look ACTIVE GALACTIC NUCLEi (CL-AGNs) are characterized by the (dis)appearance of broad emission lines on unexpectedly short timescales. However, the underlying mechanisms and their potential connection to host-galaxy properties are still unclear. In this work, we present an analysis of the morphology for 63 low-redshift CL-AGNs (z < 0.15) selected from the largest CL-AGN catalog (Guo et al. 2025) to date, using images from DESI DR10 and employing both non-parametric methods and visual inspection. We find that CL-AGN hosts exhibit a concentration like late-type spirals, asymmetry like early-type spirals, and smoothness like ellipticals. This is confirmed by their Gini-M20 coefficients, suggesting weak/modest disturbances. Based upon our visual inspection, we further identify that 18 (29%) out of 63 sources are mergers, among which ~56% (10/18) show shell features. Compared to different non-CL-AGN samples, CL-AGN hosts have a higher (~2\times) possibility of being merging systems. Our results indicate that mergers/interactions may play an important role in driving the changing-look behavior.
[abstract 44 / 53] (score: 2) - Title: Rapid quasi-periodic reconfiguration of the accretion column in pulsar 1A 0535+262Authors: Lingda Kong, Xiaohang Dai, Andrea Santangelo, Long Ji, Valery F. Suleimanov, Alexander A. Mushtukov, Lorenzo Ducci, Shu Zhang, Qingcang Shui, Shuang-Nan Zhang, Hua Feng, Sergey S. Tsygankov, Honghui Liu, Pengju Wang, Qi Liu,Comments:Subjects: astro-ph.HECreated: 2026-06-01; Updated: 2026-06-02; Datestamp: 2026-06-02
Accretion onto strongly MAGNETized neutron stars is commonly interpreted using quasi-steady models, in which the accretion-column structure adjusts smoothly to the mass inflow rate. The cyclotron line in the X-ray spectrum, whose centroid energy traces the MAGNETic field strength and thus the height of the line-forming region, provides a key diagnostic of this structure. Whether this simple quasi-steady description remains valid on short dynamical timescales has remained uncertain. Here we show that, during a giant outburst of the X-ray pulsar 1A~0535+262, quasi-periodic hard X-ray flux variations are accompanied by synchronized oscillations of the cyclotron line energy, with amplitudes exceeding those expected from simple accretion-rate fluctuations. The anti-correlation between cyclotron energy and apparent flux provides direct spectral-timing evidence for rapid changes in the line-forming region, which we interpret as geometric reconfiguration of the accretion column. The variability emerges in the luminosity regime where radiation pressure becomes dynamically important. These results reveal limitations of a simple quasi-steady interpretation for this source and suggest that radiation-supported columns can enter intrinsically dynamical states in high-luminosity accreting pulsars.
[abstract 45 / 53] (score: 2) - Title: Possible High-Energy Neutrino Emission from Dark Matter Annihilation in the Disrupting Dwarf Galaxy Boötes~IIIAuthors: Shunhao Ji, Zhongxiang Wang,Comments: 7 pages, 6 figures, submitted to PRLSubjects: astro-ph.HECreated: 2026-06-01; Updated: 2026-06-02; Datestamp: 2026-06-02
We report the first search for high-energy neutrino emissions from DARK MATTER (DM) annihilation in stellar-stream cores. Motivated by a recent gamma-ray study that proposed these cores as a new class of indirect DM targets, we analyze three stream cores in the Northern Hemisphere using the public ten-year track-like neutrino data released by IceCube. Under the $χχ\toν\barν$ annihilation hypothesis, the most significant excess among the three targets is found at the position of the nearby dwarf galaxy Boötes~III, the core of the Styx stream, with a best-fit DM mass of 26.5\,TeV. The excess has a post-trial significance of $3.1σ$. Considering the existing IceCube dwarf-galaxy limit for the same channel, we obtain a limit on the J-factor $J_{\rm ann}$, $\log_{10}(J_{\rm ann}/{\rm GeV^2\,cm^{-5}})\gtrsim 19.1^{+0.3}_{-0.5}$. This limit is broadly consistent with empirical estimates of $J_{\rm ann}$ for Boötes~III. The results provide the first candidate target with a possible HE neutrino signal associated with DM annihilation. This neutrino excess and the general existence of DM-induced neutrino signals from other similar sources will be confirmed with the near-future large high-energy neutrino detectors, thus enabling us to probe the nature of DM particles.
[abstract 46 / 53] (score: 2) - Title: Mass and Spin Growth of Very Massive Stars in Star Clusters Potentially Associated with Little Red DotsAuthors: Ataru Tanikawa, Masaru Shibata, Kunihito Ioka,Comments: 12 pages, 3 figures, 1 tableSubjects: astro-ph.HE astro-ph.CO astro-ph.GA astro-ph.SRCreated: 2026-06-01; Updated: 2026-06-02; Datestamp: 2026-06-02
Using gravitational $N$-body simulations, we investigate the evolution of mass and spin for very massive stars (VMSs) in dense star clusters, which may be potentially associated with Little Red Dots (LRDs). Our results show that VMS masses can reach $10^3$--$10^4\,M_\odot$, depending on the initial conditions of the host clusters. Notably, the VMS mass increases by up to a factor of three when accounting for the bloated state at the Hayashi track induced by stellar collisions, provided that this state is maintained at accretion rates exceeding $3 \times 10^{-2}\,M_\odot\,{\rm yr}^{-1}$. In all cases, the spin of the VMS, when normalized to the dimensionless BLACK HOLE (BH) spin parameter, exceeds $10$. While our model may overestimate VMS masses and spins due to the omission of post-main-sequence evolution and the loss of mass and angular momentum during collisions, we nonetheless demonstrate that VMSs formed in dense star clusters can be highly spinning. Such a rapidly spinning VMS is expected to collapse into an intermediate-mass BH surrounded by a massive accretion disk. This BH-disk system could trigger powerful explosions and emit burst gravitational waves, similar to those observed in GW190521 and GW231123, for which the remnant BH masses are estimated to be $\gtrsim 100\,M_\odot$.
[abstract 47 / 53] (score: 2) - Title: The gravitational wave-BLACK HOLE imaging correspondence for modified BLACK HOLEsAuthors: David Díaz-Guerra, Ángel Rincón, Diego Rubiera-Garcia, Diego Saez-Chillon Gomez,Comments: 14 pages, 2 figures, revtex4-2 styleSubjects: gr-qcCreated: 2026-06-01; Updated: 2026-06-02; Datestamp: 2026-06-02
Black holes (BHs) can be studied via fundamentally different observational channels that probe complementary aspects of their physics. While BH imaging provides access to the quasi-static space-time geometry via the strong bending of light rays, gravitational wave (GW) observations probe the dynamical response of the space-time to time-dependent processes in the inspiral, merger and ringdown phases. Both messengers -- electroMAGNETic imaging probes and ringdown GW spectroscopy --, provide access to essentially the same region -- the one between the BH event horizon and the photon region --, but they do it via conceptually different methods, encoding different physical information. However, it has been shown in the literature that physical quantities supposedly exclusive of each such messenger are actually tightly related to each another via a correspondence that occurs in the eikonal limit (i.e. large values of the multipole number $\ell$) of the geometric-optics approximation. In this paper we clarify the actual identification of observables within such a correspondence and test its accuracy for a bunch of modified spherically symmetric BH geometries proposed in the literature. We find that even for low values of $\ell$ the correspondence is surprisingly accurate in relating the real and imaginary parts of quasi-normal modes in the GW ringdown phase with the critical impact parameter and Lyapunov exponent of nearly-bound light trajectories for every such model analyzed. We discuss the applicability of such a result both for each messenger individually, and also for foreseeable tests of BHs combining both messengers.
[abstract 48 / 53] (score: 2) - Title: Revealing the high redshift host galaxy of the short GRB 061201 with JWSTAuthors: Yuhan Mao, Hanrui He, Jia Ren, Yun Wang, Hao Zhou, Qiuli Wang, Yiming Zhu, Zhiping Jin, Daming Wei,Comments: 16 pages, 12 figuresSubjects: astro-ph.HECreated: 2026-06-01; Updated: 2026-06-02; Datestamp: 2026-06-02
Using deep near-infrared and optical images from JWST and HST, we identify a new host galaxy candidate for GRB 061201. It lies ~2" from the optical afterglow position. Photometric redshift fitting yields z~1.2. We compare the previously proposed host at z=0.111 with the new candidate. The chance-coincidence probability is $P_{cc}=0.18$, above the classical threshold of 0.1 but consistent with a physical association given the extreme depth of JWST imaging. In contrast, evaluated with corresponding JWST observations, the previously claimed host has a lower $P_{cc}=0.11$, which is driven primarily by bright-tail statistics rather than a more plausible association. A high-z origin is favored by three independent lines of evidence. First, for the z=0.111 scenario, the beaming-corrected energy shows GRB 061201 is an outlier of the Ghirlanda ($E_{p,i}-E_γ$) relation for short GRBs, while for the z=1.2 scenario, it is well consistent with the Amati relation. Second, deep near-infrared observations rule out a kilonova similar to AT2017gfo at z=0.111. Third, afterglow modeling yields an AIC criterion of $Δ$AIC=16.35, providing strong evidence for the high-redshift scenario. Assuming the host candidate is the actual host galaxy of GRB 061201, the physical offset is 16.4-16.9 kpc (substantially reduced from ~42 kpc) and the host stellar age is ~2 Gyr, which are consistent with the host population of short GRBs. A low-redshift origin would lead to a very high binary neutron star merger rate of ~1400 Gpc$^{-3}$ yr$^{-1}$, which is contradictory to the gravitational-wave constraint. We suggest that GRB 061201 originates from a moderately high-redshift (z~1.2) host, significantly alleviating this apparent merger rate discrepancy. This case demonstrates the power of deep JWST exposures in revealing the host galaxies of historically hostless GRBs.
[abstract 49 / 53] (score: 2) - Title: The Diocotron Instability in the Trapped Electrons Experiment T-REX and its Relevance to Electron Clouds in Gyrotron GunsAuthors: Francesco Romano, Pierrick Giroud-Garampon, Joaquim Loizu, Giulia Scimone, Jean-Philippe Hogge,Comments:Subjects: physics.plasm-phCreated: 2026-06-01; Updated: 2026-06-02; Datestamp: 2026-06-02
Gyrotrons are essential for electron cyclotron resonance heating (ECRH) in fusion reactors, making their efficient operation crucial for fusion energy. Past experiments revealed instability issues due to trapped electrons in the MAGNETron injection gun (MIG) region, causing undesired currents and operational failures. To address this, tight manufacturing tolerances are required for the MIG geometry~\cite{pago2}. We present findings of the TRapped Electrons eXperiment (T-REX) at the Swiss Plasma Center, designed to understand electron cloud physics in gyrotron MIGs. T-REX replicates MIG geometries, electric and MAGNETic fields, and is supported by the 3D FENNECS code. The setup includes two coaxial electrodes in a vacuum chamber atop a superconducting MAGNET; a central electrode is biased to negative DC voltages and an outer one is grounded, creating a radial electric field up to 2 MV/m and an axial MAGNETic field B < 0.31 T. Initial discrepancies between experiments and simulations were linked to the diocotron instability, leading to FENNECS being upgraded to 3D and a dedicated set of diagnostics for T-REX. This instability causes the electron cloud to collapse and reform at a frequency depending on plasma conditions. Within this article, time-resolved current measurements on the outer electrode and top flange are presented. Further, a fast current probe array installed at the top flange is detailed. Measurements highlight rotating structures in the electron cloud resulting from the diocotron instability. Simulations show remarkable agreement with experiments, especially regarding the cloud's build-up/collapse frequency, and the rotation frequency and direction of the modes. These results improve our understanding of non-neutral plasmas in environments mimicking a real gyrotron MIG, paving the way for better gyrotron reliability.
[abstract 50 / 53] (score: 2) - Title: The First Detection of Sub-Populations in the Delay-Time Distribution of Binary Black Holes in GWTC-4 of LIGO-Virgo-KAGRAAuthors: Shaunak Padhyegurjar, Suvodip Mukherjee,Comments: 12 pages, 6 figures and 1 appendix. Comments are welcome!Subjects: astro-ph.HE astro-ph.CO gr-qcCreated: 2026-06-01; Updated: 2026-06-02; Datestamp: 2026-06-02
The imprint of different formation channels of binary BLACK HOLEs (BBHs) is encoded in the distribution of time delays between BBH mergers and the formation of their progenitor stars, along with their source properties such as component mass, mass-ratio, spin, and more. This makes it possible for the presence of a potential correlation between the delay-time distribution and compact-object source properties. We report the first measurement of this inevitable signature from the fourth gravitational wave (GW) catalog (GWTC-4) of LIGO-Virgo-KAGRA and identified three sub-populations that show distinct merger rate behavior as a consequence of this. We find that the delay-time distribution of the sources above a mass of $45$ M$_\odot$ is significantly different from the ones below and exhibits strong dependence on the mass-ratio and spin, indicating that GW sources close to equal masses and close to zero effective spin are more delayed in comparison to the values otherwise. Our analysis identifies the presence of at least three source property dependent sub-population of merger rates with the merger rate at redshift $z=0$ varying from $\sim 0.6- 12$ Gpc$^{-3}$ yr$^{-1}$ for the three different sub-populations and hence rule out a Universal merger rate for all the BBHs detected using GW.
[abstract 51 / 53] (score: 2) - Title: Solar vortex detection methods in MHD simulations: impact of MAGNETic field and spatial resolutionAuthors: M. Koll Pistarini, E. Khomenko, T. Felipe, M. Modestov,Comments: Accepted for publication in A&A, 17 pages, 10 figuresSubjects: astro-ph.SRCreated: 2026-06-01; Updated: 2026-06-02; Datestamp: 2026-06-02
The aim of this paper is to investigate the influence of different MAGNETic field configurations and spatial resolutions on vortex structures. We analyzed a set of six three-dimensional realistic simulations of the solar atmosphere under three different MAGNETic field configurations: a small-scale dynamo and two initially vertical implanted MAGNETic fields of 50 G and 200 G. Three different spatial resolutions have been employed: 20x20x14, 10x10x7 and 5x5x3.5 km^3. We applied two vortex detection methods based on the velocity gradient tensor to all of the models: swirling strength and the SWIRL code. We performed a comparison of vortex locations obtained with both methods, and a statistical analyses of the vortex generation mechanisms, the area covered by vortices, their number and characteristic sizes, and temperature profiles as a function of height. We have confirmed that different MAGNETic field configurations and spatial resolutions impact the area coverage, number, and sizes of vortices. Likewise, the detection methods impact the statistics obtained. Swirling strength detects vortices with any orientation but a height-dependent threshold is needed. SWIRL only detects vertically-oriented vortices but shows a better agreement with the rotating horizontal velocity field. Simulations with a vertical MAGNETic field of 50 G support the formation of chromospheric vortices without a photospheric counterpart, while most of the vortices in the 200 G model directly connect the photosphere with the chromosphere. Small-scale dynamo simulations are characterized by a large number of horizontal vortices, with vertical vortices being nearly absent at chromospheric layers. Temperature profiles of vortices confirm that they are hotter than their surroundings, regardless the simulation setup.
[abstract 52 / 53] (score: 2) - Title: Resistive wall mode induced disruptions in an advanced tokamakAuthors: Sui Wan, Ping Zhu,Comments:Subjects: physics.plasm-phCreated: 2026-06-01; Updated: 2026-06-02; Datestamp: 2026-06-02
Resistive wall mode is one of the leading causes for tokamak disruptions above the no-wall $β_N$ limit. This paper presents nonlinear three-dimensional resistive MHD simulations of an RWM-induced disruption in a CFETR baseline steady-state equilibrium using the NIMROD code. Linear calculations confirm the dominant presence of the $n=1$ RWM instability, whose growth rate is strongly sensitive to the wall response and becomes weakly dependent on plasma resistivity in the high-$S$ limit, along with a global external-kink-like structure. In the nonlinear phase, the RWM drives rapid flux surface stochastization and a thermal quench, followed by a current quench that is intensified by the post quench increase of Spitzer resistivity. The transient current spike before the current quench is shown to be the outcome of the conservation of poloidal flux and a rapid reduction of internal inductance. During the late current quench stage, closed flux surfaces partially reform from the core region to the edge, relaxing toward the force-free state. Toroidal mode coupling, parallel heat transport, plasma resistivity, and wall conductivity strongly modulate the disruption onset and the quench dynamics. Within the MHD model, these results provide a complete view on the RWM-driven disruption process in advanced tokamak configurations.
[abstract 53 / 53] (score: 2) - Title: On the Relationship between Solar Spicules and Propagating Coronal Disturbances: The Role of ShocksAuthors: Ravi Chaurasiya, Sankalp Srivastava, Piyali Chatterjee, Sahel Dey, Robertus Erdélyi, Ankala Raja Bayanna,Comments: 16 pages, 13 figures. Accepted for publication in ApJSubjects: astro-ph.SRCreated: 2026-06-01; Updated: 2026-06-02; Datestamp: 2026-06-02
Spicules and propagating coronal disturbances (PCDs) are ubiquitous dynamic features of the solar atmosphere, yet their physical connection remains an open question of paramount importance to the mass and energy transport in the solar atmosphere. Using concurrent multiwavelength high-resolution observations from the Swedish 1-m Solar Telescope and the Solar Dynamics Observatory, supported with two-dimensional radiative MAGNETohydrodynamic (MHD) simulations, we find that i) shock waves in the chromosphere generated from non-linear wave steepening drive some spicules, ii) in the corona, these shock waves may transition into large amplitude non-linear compressive MHD waves depending on the MAGNETic field strength and the ambient coronal conditions. In either case, the shocks or the large-amplitude compressive waves in the corona, also transport upward mass flux and produce intensity variations in the form of PCDs in coronal passbands. Further a multi-height wavelet analysis shows dominant $\sim$5 minute periods in the lower chromosphere that evolve into longer periods ($\ge$10 minutes) at higher atmospheric layers, consistent with dispersive propagation in a stratified medium. The observational characteristics together with the numerical simulations, demonstrate that a shock-driven MHD mechanism links spicule formation to coronal disturbances. Finally, mass flux estimates from both the observations and the simulations indicate that these PCDs can also aid in supplying mass to the solar wind.
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