Current date: 2026-06-17
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Created/updated limit: 2026-06-10 (7 days ago)
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Scoring abstracts
Number of records retrieved: 719
Keyword score statistics
score 9 -- 1 abstracts
score 8 -- 2 abstracts
score 7 -- 1 abstracts
score 6 -- 3 abstracts
score 5 -- 2 abstracts
score 4 -- 7 abstracts
score 3 -- 11 abstracts
score 2 -- 23 abstracts
in total -- 50 abstracts
Articles that appeared on 2026-06-17
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[abstract 1 / 50] Wow! (score: 9)
- Title: Revisiting Disk Winds in Active Galactic Nuclei as an Origin of Cosmic Gamma-ray and Neutrino BackgroundsAuthors: Nobuyuki Sakai, Yoshiyuki Inoue, Ellis R. Owen,Comments: 26 pages, 10 figures, 4 tables; accepted for publication in The Astrophysical JournalSubjects: astro-ph.HE astro-ph.GACreated: 2026-06-16; Updated: 2026-06-17; Datestamp: 2026-06-17
The origin of the cosmic neutrino background (CNB) and the cosmic gamma-ray background (CGB) remains uncertain. Accretion disk winds driven by ACTIVE GALACTIC NUCLEi (AGNs) have been proposed as possible contributors, but their predicted background levels depend sensitively on poorly constrained wind energetics and ambient densities. We revisit the AGN disk-wind scenario by constructing a lepto-hadronic wind model calibrated with radio and GeV gamma-ray data of nearby FERMI-LAT-detected Seyfert galaxies. In our framework, COSMIC RAYs accelerated both at wind-driven forward and reverse shocks produce SYNCHROTRON, external-Compton, and hadronic emission. We also incorporate recent XRISM constraints on wind parameters. Applying our calibrated lepto-hadronic models to an AGN population synthesis model, we find that disk winds contribute at most $\lesssim 5\%$ of the CGB above 10 GeV and $\lesssim 10\%$ of the CNB around 100 TeV, suggesting that they are unlikely to dominate both backgrounds. Finally, we identify nearby Seyfert galaxies hosting ultrafast outflows as promising targets for future TeV gamma-ray and TeV$-$PeV neutrino observations, which would offer firm tests of the disk-wind scenario.
[abstract 2 / 50] Wow! (score: 8) - Title: Axion-like particle limits from multi-messenger sourcesAuthors: Ariane Dekker, Gonzalo Herrera, Dimitrios Kantzas,Comments: 9 pages, 3 figures; Comments welcome. v2: Accepted for publication in PRDSubjects: hep-ph astro-ph.HECreated: 2026-06-16; Updated: 2026-06-17; Datestamp: 2026-06-17
High-energy neutrino observation from the Seyfert galaxy NGC 1068 offers new insights into the non-thermal processes of ACTIVE GALACTIC NUCLEi. Simultaneous gamma-rays emitted by such sources can possibly oscillate into axion-like particles (ALPs) when propagating through astrophysical MAGNETic fields, potentially modifying the observed spectrum. To probe for ALP-induced signals, a robust understanding of the emission processes at the source is necessary. In this work, we perform a dedicated multi-messenger analysis by modeling a JET in the innermost vicinity of the central supermassive BLACK HOLE of NGC 1068. We model in particular the neutrino and gamma-ray emission originating in lepto-hadronic collisions between JET accelerated particles and background particles from the corona, reproducing both the FERMI-LAT and IceCube data. These source models serve as a baseline for ALP searches, and we derive limits on the ALP-photon coupling by marginalizing over motivated ranges of astrophysical parameters. We find $g_{aγ} \lesssim 7 \times 10^{-11}$GeV$^{-1}$ for $m_a \lesssim 10^{-9}$ eV. These limits may be weaker than existing constraints, but they demonstrate the potential of multi-messenger observations to probe new physics. We conclude by discussing how additional upcoming multi-messenger sources and improved observational precision can enhance ALP sensitivity.
[abstract 3 / 50] Wow! (score: 8) - Title: Optical POLARIZATION variability and its relation to gamma-ray activity in BLAZARsAuthors: Styliana Grigoriou, Anastasia Glykopoulou, Ioannis Liodakis,Comments: Accepted for publication in Astronomy & Astrophysics. Manuscript no. aa60588-26. 5 pages, 4 figuresSubjects: astro-ph.HECreated: 2026-06-15; Updated: 2026-06-17; Datestamp: 2026-06-17
Optical POLARIZATION can be an important probe of particle acceleration and high-energy emission processes in RELATIVISTIC JETs from supermassive BLACK HOLEs. We combined publicly available observations from three past BLAZAR monitoring programs to produce densely sampled light curves for 15 BLAZARs in order to explore the relation of gamma-ray activity to the POLARIZATION variability as well as discover new rotations of the POLARIZATION angle. We find that the POLARIZATION degree does not correlate with the gamma-ray flux for individual sources nor different subsamples of BLAZARs, potentially indicating multiple emission mechanisms. In the combined dataset, we identified a total of 64 rotations in 12 sources, 39 of which are newly identified rotations. We confirm the trend found in previous works for the whole sample: lower POLARIZATION degrees during periods of POLARIZATION angle rotations. However, looking at the individual sources, we identified cases where the rotation and non-rotation POLARIZATION degree distributions are indistinguishable, providing further evidence for the multiple emission mechanism hypothesis.
[abstract 4 / 50] Wow! (score: 7) - Title: Detailed Timing, Spectral, and Polarimetric Analysis of Magnetar 1RXS J170849.0-400910Authors: Rachael Stewart, George Younes, Alice Harding, Hoa Dinh Thi, Matthew Baring, Zorawar Wadiasingh, Michela Negro, Alex Van Kooten,Comments: submitted to ApJ; comments welcomeSubjects: astro-ph.HECreated: 2026-06-16; Updated: 2026-06-17; Datestamp: 2026-06-17
We present a broadband timing, spectral, and polarimetric study of the MAGNETar 1RXS~J170849.0-400910 using XMM-Newton, NUSTAR, and IXPE. The pulse morphology evolves strongly across 0.5-70 keV. Below 3 keV, the emission is dominated by a broad soft pulse with a leading shoulder that develops into a faint interpulse near 3 keV, while the pulse fraction remains $\approx$25%. The profile becomes increasingly double-peaked between 3 and 20 keV and returns to a single peak at higher energies. The pulse fraction dips to $\sim$20% near 4 keV and rises to $\sim$42% above 25 keV. The phase-averaged spectrum is well described by an absorbed blackbody plus two power-laws, with $kT=0.468\pm0.003$ keV, $Γ_{\rm soft}=2.63\pm0.04$, and $Γ_{\rm hard}=0.5\pm0.1$. Phase-resolved spectroscopy reveals distinct soft and hard pulse components. The thermal modulation is driven primarily by a factor of $\sim$5 variation in projected emitting area, whereas the soft power-law exhibits two peaks with different phase and energy evolution, suggesting distinct emission regions or mechanisms. The 10-70 keV flux is strongly anticorrelated with the soft power-law photon index, linking spectral hardening to the hard pulse. The POLARIZATION degree also varies strongly with phase and energy. In the 2-3 keV band, it is anticorrelated with the intensity profile, consistent with MAGNETized-atmosphere emission, whereas in the 4-8 keV band it reaches $64\pm10$% during the nonthermal power-law-dominated peak. This high POLARIZATION can be reproduced by MAGNETospheric quantum pair-SYNCHROTRON emission. Together, these results reveal an intricate, phase-dependent superposition of emitting regions and radiative processes whose complexity emerges only through broadband, phase-resolved spectropolarimetry.
[abstract 5 / 50] Yes (score: 6) - Title: Universal behaviour of $α$-viscosity in BLACK HOLE accretion discsAuthors: Marek A. Abramowicz, Axel Brandenburg, Jiří Horák, Debora Lančová, John C. Miller, Ewa Szuszkiewicz, Maciek Wielgus,Comments: 9 pages, 3 figures, submitted to Astronomy&Astrophysics, revised version: minor revisions following referee commentsSubjects: astro-ph.HECreated: 2026-06-16; Updated: 2026-06-17; Datestamp: 2026-06-17
The Shakura-Sunyaev $α$-viscosity coefficient, defined as the ratio of total stress to total pressure, $α= \mathbb{T}/p$, began to play an important role in the development of accretion disc theory in the early 1970s. The origin of the turbulence that causes the stress $\mathbb{T}$ was unknown at that time; Shakura and Sunyaev assumed $α=$\,const. Today we know that this was not quite realistic -- modern general RELATIVISTIC MAGNETo-hydrodynamic simulations (GRMHD) of BLACK HOLE accretion discs have revealed that $α$ changes by about an order of magnitude within the disc, being smaller far away from the BLACK HOLE and larger in the plunging region close in, and it has been found that the behaviour of $α$ reflects some underlying, fundamental properties of the stress $\mathbb{T}$. In particular, it has been argued by several authors, that $\mathbb{T}$ must be zero at the BLACK HOLE horizon. We note that the stress calculated in three independent GRMHD simulations of accretion discs around non-rotating BLACK HOLEs, made by a variety of authors (including ourselves), each has its prominent maximum close to the location of the circular photon orbit. We propose a formula that accurately describes this ``universal'' behaviour of $α$ in terms of the ``gyration radius'', a physical characteristic of rotation well known in Newtonian dynamics and in the BLACK HOLE case uniquely defined by the Kerr space-time geometry. Analytic and semi-analytic models of BLACK HOLE accretion discs provide an invaluable insight into fundamental physics, and the GRMHD simulations do not aspire to replace them. Rather, simulations could help to improve analytic models by making them more realistic. For example, our $α$-formula, deduced from the GRMHD simulations, may be useful in the construction of improved versions of thin and slim disc models.
[abstract 6 / 50] Yes (score: 6) - Title: A catalogue of TeV pulsar environmentsAuthors: Tina Wach, Tim Linden, Alison M. W. Mitchell, Samuel T. Spencer,Comments: 11 pages, 6 figures, 3 tables, accepted for publication in Astronomy&AstrophysicsSubjects: astro-ph.HECreated: 2026-06-16; Updated: 2026-06-17; Datestamp: 2026-06-17
Pulsars and their environments represent a major class of Galactic gamma-ray sources. Their complex evolution, shaped by the interactions of the pulsar outflow with the SUPERNOVA remnant (SNR) and the surrounding interstellar medium (ISM), produces diverse morphological and spectral characteristics observable from radio to PeV energies. This work collects and homogenizes data from all major operating TeV observatories, presenting the first comprehensive catalogue of TeV gamma-ray properties of pulsar environments.The catalogue is created from information regarding all gamma-ray sources that have been classified as pulsar-associated sources in published results from H.E.S.S., MAGIC, VERITAS, HAWC, and LHAASO. For each source, the observed gamma-ray properties are cross-matched with pulsar properties from the ATNF catalogue and FERMI-LAT pulsar catalogue. The final catalogue comprises all currently known TeV sources associated with pulsars, spanning all evolutionary stages. The sample consists of 128 gamma-ray sources, connected to 66 different pulsars. It reflects that the TeV-detected population is dominated by young and energetic pulsars located near the Galactic plane, but includes a growing number of middle-aged systems detected as extended halos. Only a weak correlation is found between TeV luminosity and pulsar characteristic age, indicating that TeV evolution is driven by environmental and transport effects rather than by spin-down age alone. Additionally, 5 pulsars which should host a PWN detectable by CTAO are identified as prime targets for future observation to improve our understanding of properties inhibiting the formation of a TeV nebula. This publicly available catalogue provides a uniform foundation for future population studies and for constraining models of particle transport and energy losses in pulsar environments.
[abstract 7 / 50] Yes (score: 6) - Title: Polarized emission of orbiting hot-spots near Sagittarius A*: effects of electroMAGNETic interactionAuthors: Abylaikhan Tlemissov, Arman Tursunov, Maciek Wielgus,Comments: 10 pages, 6 figures; accepted to Astronomy & AstrophysicsSubjects: astro-ph.HE gr-qcCreated: 2026-06-16; Updated: 2026-06-17; Datestamp: 2026-06-17
We investigate the polarimetric signatures of orbiting hot-spots around a Schwarzschild BLACK HOLE in the presence of an external MAGNETic field, accounting for the electroMAGNETic interaction between the charged emitter and the field. Using a general-RELATIVISTIC model that incorporates SYNCHROTRON emission and ray-tracing of light propagation, we analyze how the electroMAGNETic interaction parameter modifies the observed POLARIZATION patterns, with particular emphasis on the behavior of the electric vector position angle (EVPA) and the time-evolving POLARIZATION loops in the $Q$-$U$ plane. Applying the model to millimeter wavelength ALMA observations of Sagittarius~A*, we explore the parameter space that best reproduces the asymmetry, time ratio, and area ratio of the observed POLARIZATION loops. We find that the inclusion of a small positive interaction parameter increases the symmetry of the loops and the time ratio, while a negative MAGNETic parameter introduces strong asymmetry and fails to reproduce the data. Our results indicate that electroMAGNETic interaction can lead to ambiguity in the estimation of the system parameters such as orbital inclination or hot-spot velocity.
[abstract 8 / 50] Yes (score: 5) - Title: Study of an interaction between the JET and an interstellar medium of M87 with a spectral analysis by using ChandraAuthors: S. Osone,Comments: 25 pages, 4 figures. arXiv admin note: text overlap with arXiv:1408.3975:The exposure time is twice as long as original paper and the calculation of flux of non thermal bremsstrahlung is modified with an effct of a break in an index(v2):calibration data is updated and I make a correction formula of non thermal bremsstrahlung(v3)Subjects: astro-ph.HECreated: 2026-06-16; Updated: 2026-06-17; Datestamp: 2026-06-17
Both a thermal component and a non thermal component as an interaction between the JET and an interstellar medium are studied with an exposure time of 800 ks of Chandra. It is confirmed that an X ray energy spectra for the nucleus and the knot D is well described with a power law model as SYNCHROTRON emission. It is found that a power law model is rejected statistically for HST-1 and the knot A and an X ray energy spectra is well described with a combination model of a power law and a thermal bremsstrahlung of temperature of 0.2 keV and metal abundance of 0.00. There is a possibility that gas in a JET is heated by a shock as interaction between the JET and an interstellar medium and it is observed as thermal emission. The flux of a non thermal bremsstrahlung from the JET as an interaction between accelerated electrons and an interstellar medium is calculated from an X ray result and it is found that there is no contribution from both nucleus and the knot HST-1 to the observed flux with FERMI.
[abstract 9 / 50] Yes (score: 5) - Title: Sensitivities of Black Hole Images from GRMHD SimulationsAuthors: Pedro Naethe Motta, Mário Raia Neto, Cora Prather, Alejandro Cárdenas-Avendaño,Comments: 16 pages, 12 figures. V2: Minor textual changes. Published in ApJSubjects: astro-ph.HECreated: 2026-06-16; Updated: 2026-06-17; Datestamp: 2026-06-17
The advent of high-fidelity imaging of supermassive BLACK HOLEs calls for efficient and robust data-analysis methods. In this work, we use $\texttt{Jipole}$, a differentiable, $\texttt{ipole}$-based radiative transfer code, to enable gradient-based analyses of images generated from state-of-the-art general RELATIVISTIC MAGNETohydrodynamic (GRMHD) simulations. We compute image sensitivities, i.e., pixel-wise derivatives of the intensity with respect to model parameters, which form the Jacobian of the forward model and define a local map from parameter space to image space. Using these sensitivities in a mock data analysis, we find that GRMHD-based images generate a structured error landscape for parameter fitting, with anisotropies and local minima, making parameter exploration nontrivial but still tractable when guided by gradient information. We characterize this landscape through the Jacobian and assess the feasibility of gradient-based recovery under idealized, blurred, and noisy conditions. Our results show that automatic differentiation-computed image gradients can guide parameter exploration effectively even in the presence of noise. These findings establish a basis for efficient, high-precision model--data comparisons in BLACK HOLE imaging and motivate the integration of these sensitivities into advanced inference frameworks.
[abstract 10 / 50] Yes (score: 4) - Title: Kerr BLACK HOLE in presence of force-free MAGNETic fieldAuthors: Haidar Sheikhahmadi,Comments: 35 pages, 6 figures, 2 appendices; accepted in JHEAPSubjects: gr-qc astro-ph.CO hep-th math-ph math.MPCreated: 2026-06-15; Updated: 2026-06-17; Datestamp: 2026-06-17
We extend the study of force-free MAGNETospheres from non-rotating to rotating BLACK HOLEs \cite{Sheikhahmadi} and investigate the influence of a force-free MAGNETic field on the geometry around a Kerr BLACK HOLE. Using the Newman-Penrose formalism, we explicitly construct the electroMAGNETic field strength tensor in the Kerr background and compute the corresponding stress-energy tensor. The resulting metric perturbation is then obtained by solving the linearised Einstein equations. In this modified geometry, we analyse key observables of thin accretion disks, including the innermost stable circular orbit (ISCO), effective potential, energy flux, temperature, and efficiency parameter. Our results demonstrate that MAGNETic backreaction significantly alters the spacetime near the BLACK HOLE, with important consequences for accretion physics and JET-launching mechanisms such as the Blandford-Znajek process. This work underlines the essential role of MAGNETic fields in shaping RELATIVISTIC astrophysical environments.
[abstract 11 / 50] Yes (score: 4) - Title: FPIC: a new Particle-In-Cell code for stationary and axisymmetric black-hole spacetimesAuthors: Claudio Meringolo, Luciano Rezzolla,Comments: 15 pages, 11 figuresSubjects: astro-ph.HE gr-qc physics.plasm-phCreated: 2026-06-16; Updated: 2026-06-17; Datestamp: 2026-06-17
In this paper we present a newly developed GRPIC code framework called FPIC, providing a detailed description of the Maxwell-equations solver, of the particle ``pushers'', and of the other algorithms that are needed in this approach. We describe in detail the code, which is written in Fortran and exploits parallel architectures using MPI directives both for the fields and particles. FPIC adopts spherical Kerr-Schild coordinates, which encode the overall spherical topology of the problem while remaining regular at the event horizon. The Maxwell equations are evolved using a finite-difference time-domain solver with a leapfrog scheme, while multiple particle ``pushers'' are implemented for the evolution of the particles. In addition to well-known algorithms, we introduce a novel hybrid method that dynamically switches between the most appropriate scheme based on the violation of the Hamiltonian energy. We first present results for neutral particles orbiting around BLACK HOLEs, both in the Schwarzschild and Kerr metrics, monitoring the evolution of the Hamiltonian error across different integration schemes. We apply our hybrid approach, showing that it is capable of achieving improved energy conservation at reduced computational cost. We apply FPIC to investigate the Wald solution, first in electrovacuum and subsequently in plasma-filled configurations. In the latter case, particles with negative energy at infinity are present inside the ergosphere, indicating that the Penrose process is active. Finally, we present the split-monopole solution in a plasma-filled environment and successfully reproduce the Blandford-Znajek luminosity, finding very good agreement with analytical predictions.
[abstract 12 / 50] Yes (score: 4) - Title: Discovery of a Supernova Following the Einstein Probe Transient EP250302a at z = 1.131Authors: Brendan O'Connor, Malte Busmann, James Freeburn, Lei Hu, Noel Klingler, Daniel Gruen, Igor Andreoni, Julius Gassert, Xander J. Hall, Antonella Palmese,Comments: Submitted to ApJSubjects: astro-ph.HECreated: 2026-06-15; Updated: 2026-06-17; Datestamp: 2026-06-17
We present a multi-wavelength analysis of the Einstein Probe (EP) fast X-ray transient (FXT) EP250302a located at redshift $z=1.131$. Despite its luminous prompt X-ray emission, the event was not detected in gamma-rays. Multi-wavelength follow-up identified a bright optical and X-ray source that displayed rapid chromatic flaring before returning to the standard decay of a GAMMA-RAY BURST afterglow. We interpret the chromatic flare as either due to a refreshed shock caused by a discrete shell collision or as reverse shock emission. Using the early optical data, we place constraints on the Lorentz factor of the outflow, requiring an ultraRELATIVISTIC JET with $Γ_0>25$. We additionally obtained deep late-time imaging with the Gemini North Telescope that reveals the presence of an optical excess at $20-30$ d post-explosion. We interpret this as SUPERNOVA (SN) emission and find good agreement with the canonical broad-lined Ic SN 1998bw with a flux-scaling factor of $k_\textrm{98bw}>0.3$. This adds to the growing evidence that the majority of EP FXTs are associated with the deaths of massive stars.
[abstract 13 / 50] Yes (score: 4) - Title: Extreme Ultraviolet Microflashes at Plume Bases: A Candidate for Powering the Corona and Solar Wind?Authors: Navdeep K. Panesar, Sanjiv K. Tiwari, Meng Jin, Ayla Weitz, Ronald L. Moore, V. Aparna, Alphonse Sterling,Comments: 21 pages, 12 FiguresSubjects: astro-ph.SRCreated: 2026-06-15; Updated: 2026-06-17; Datestamp: 2026-06-17
Solar plumes - outflows of bright coronal plasma - are a major component of the open-MAGNETic-field corona and solar wind, but their driving mechanism remains uncertain. Here we report on network microflashes, fine-scale bright bursts captured by Solar Orbiters Extreme Ultraviolet Imager in 174A images encompassing MAGNETic network at the base of plumes. Because they sit in evidently unipolar MAGNETic flux, they are evidently a new, previously unidentified, kind of network event. Approximately 20 microflashes are ongoing within a plume base, with a new microflash starting every second. The energy for an average microflash is 1024 erg, in the range of nanoflares. A 3D data-driven global MHD model yields open MAGNETic field with fast solar wind for the investigated plumes. From our findings, we suggest that network microflashes result from fine-scale bursts of RECONNECTion of crossed legs of unipolar MAGNETic field, that the bursts are often triggered by 5-minute p-mode oscillations, and that the bursts are candidates for powering the open-field corona and solar wind. That is, unipolar microflashes such as ours are plausibly from unipolar-network-field RECONNECTion bursts that sustain the heliosphere.
[abstract 14 / 50] Yes (score: 4) - Title: GRB 250424A: A Case Study of Energy Injection with Multiwavelength ObservationsAuthors: Yifang Liang, Yun Wang, WeiKang Zheng, Priyadarshini Gokuldass, Huali Li, Chenwei Wang, Riccardo Brivio, Donovan Schlekat, Alexei V. Filippenko, Pillas Marion, Dalya Akl, Sarah Antier, Manasanun Tanasan, Kanthanakorn Noysena, Di Xiao, Jie An, Thomas G. Brink, Krittapas Chanchaiworawit, Dylan A. Dutton, Matteo Ferro, Michael Freeberg, Ren Jia, Alain Klotz, Ye Li, Xing Liu, Dan Reichart, Antonio C. Rodriguez, Wenjun Tan, Samaporn Tinyanont, Jing Wang, Zi-Qi Wang, Jianyan Wei, Samuel E. Whitebook, Xuefeng Wu, Dong Xu, Yi Yang, Jinpeng Zhang, Wenlong Zhang, Hao Zhou, Valerio D'Elia, Massimiliano De Pasquale, Dino Fugazza, Luciano Nicastro, Damien Turpin, Roger Hellot, Frederic Dux, Xiangyu Wang, Frederic Daigne, Yongfeng Huang, HongBo Cai, Alexis Coleiro, Bertrand Cordier, Stefano Crepaldi, YongWei Dong, Olivier Godet, XuHui Han, Frederic Piron, YuLei Qiu, Stephane Schanne, Chao Wu, LiPing Xin, Yang Xu, Shuangnan Zhang, ShiJie Zheng,Comments: 24 pages, 10 figures, 3 tables, accepted for publication in ApJSubjects: astro-ph.HECreated: 2026-06-16; Updated: 2026-06-17; Datestamp: 2026-06-17
We present a comprehensive multiwavelength analysis of the long-duration GAMMA-RAY BURST (GRB) 250424A. Our dataset spans from the prompt gamma-ray emission to late-time optical monitoring, including spectra obtained with the Keck 10\,m telescope. We find that the afterglow light curves display a prominent, simultaneous shallow decay phase in both X-ray and optical bands, followed by an achromatic transition to a standard decay regime. The broadband spectral energy distributions are well-modeled by a single power-law function, indicating a common SYNCHROTRON origin for the emission across frequencies. We interpret the afterglow evolution within the framework of a RELATIVISTIC forward shock refreshed by continuous energy injection. This scenario successfully reproduces the observed temporal and spectral behavior, yielding an isotropic equivalent kinetic energy of $E_{\rm K,iso} \approx 5.5 \times 10^{52}$ erg and an injection index of $q\approx 0.34$ in a constant-density circumburst environment. The shallow decay phase is consistent with sustained energy injection lasting $\sim$ 9 ks. Despite the relatively low redshift, late-time optical observations reveal no distinct SUPERNOVA component; however, our derived upper limits do not strictly rule out the presence of a typical GRB-associated SUPERNOVA.
[abstract 15 / 50] Yes (score: 4) - Title: Discovery of a quasi-periodic oscillation non-harmonically related to the Type-C QPO in the hard intermedidate state of MAXI J1820+070Authors: Pei Jin, Mariano Méndez, Federico García, Diego Altamirano, Ruican Ma,Comments: 11 pages, 7 figures, 1 table; accepted for publication in Astronomy & AstrophysicsSubjects: astro-ph.HECreated: 2026-06-16; Updated: 2026-06-17; Datestamp: 2026-06-17
We present a detailed timing analysis of the transition from the hard-intermediate state (HIMS) to the soft-intermediate state (SIMS) in MAXI J1820+070 using NICER observations. This transition is marked by a sharp drop of the broadband noise across both the soft and hard X-ray bands, the disappearance of the Type-C quasi-periodic oscillation (QPO), the quenching of the steady, optically thick, compact JET, the appearance of a Type-B QPO, and the detection of discrete, optically thin, radio ejections. For the first time, we detect a QPO at 3.5-5.9 Hz in the 2-12 keV power density spectrum of MAXI J1820+070 roughly half a day before the transition, which appears to evolve smoothly into the Type-B QPO observed immediately after the transition. The location of this additional QPO component in the broadband rms vs. QPO frequency plot is consistent with that of the Type-B QPOs in GX 339-4 and GRO J1655-40, suggesting a possible connection between this additional QPO in the HIMS and the Type-B QPO in the SIMS. This result, together with recent findings in SWIFT J1727.8-1613, suggests that QPOs with these characteristics can emerge prior to the HIMS-to-SIMS transition and are not confined exclusively to the SIMS. If this additional QPO feature is the precursor of the Type-B QPO in the SIMS, its presence before the transition, whereas the bright discrete, optically thin, radio ejections appear at the transition, would imply that there may be no direct physical connection between the Type-B QPO and the discrete radio ejections. Our results further suggest a link between the disappearance of the Type-C QPO, the drop of the broadband noise, and the emergence of discrete radio ejections at the HIMS-to-SIMS transition. We speculate that the simultaneous presence of such a QPO, non-harmonically related to the Type-C QPO in the HIMS, could be compatible with a spine-sheath outflow structure.
[abstract 16 / 50] Yes (score: 4) - Title: X-ray eclipse tomography: Resolving the extent of X-ray-emitting region(s) in the Seyfert galaxy ESO362-G18Authors: Laura Rueda-Nieto, Beatriz Agís-González, Giovanni Miniutti,Comments: Accepted for publication in A&ASubjects: astro-ph.HECreated: 2026-06-16; Updated: 2026-06-17; Datestamp: 2026-06-17
X-ray spectral variability in ACTIVE GALACTIC NUCLEi (AGNs) can be either intrinsic or caused by external processes, such as variable absorption. Several transient occultation events from individual clouds or X-ray eclipses have been identified in a number of AGNs in the past two decades. We report results from the analysis of two SWIFT monitoring campaigns of the Seyfert galaxy ESO 362-G18, a changing-look AGN that showed transitions between optical spectral types 1.5 and 1.9 in the past, most likely induced by variable absorption. We identified two X-ray eclipses during the first SWIFT campaign, one of which we were able to follow almost entirely from ingress to egress. We used time-resolved spectroscopy to follow the evolution of the X-ray spectrum with time in order to derive the properties of the absorbing cloud and the size of the main X-ray-emitting region. The cloud is located towards the innermost dust sublimation zone, intermediate between the dust-free broad-line region and the dusty torus. The X-ray-emitting region is confined within 35 gravitational radii (Rg) from the centre. A deeper analysis indicated that the eclipsing cloud likely comprises a denser core and a more tenuous atmosphere. We were also able to estimate the size of the soft excess and hot corona X-ray-emitting regions separately. These are two of the most relevant continuum components in the X-ray spectra of unobscured AGNs. Our analysis suggests that the soft-excess-emitting region is 50% more extended than the hot corona one. However, it appears to co-exist with and is not replaced by the hot corona one in the innermost 30 Rg. Our results highlight the potential of X-ray eclipse tomography for providing a clearer view of the innermost accretion flow geometry and of the AGN surroundings out to the torus scale.
[abstract 17 / 50] (score: 3) - Title: Relativistic MAGNETohydrodynamics in the early UniverseAuthors: Alberto Roper Pol, Antonino Salvino Midiri,Comments: 73 pages, 4 figures, 1 table, updated version with minor corrections, approved for publicationSubjects: gr-qc astro-ph.COCreated: 2026-06-16; Updated: 2026-06-17; Datestamp: 2026-06-17
We review the conservation laws of MAGNETohydrodynamics (MHD) in an expanding homogeneous and isotropic Universe that can be applied to the study of early Universe physics during the epoch of radiation domination. The conservation laws for a conducting perfect fluid with RELATIVISTIC bulk velocities in an expanding background are presented (for the first time in their non-conservation form, i.e., as dynamical equations for the velocity and energy density fluid variables), and extending previous results that apply in the limit of subRELATIVISTIC bulk motion. Furthermore, it is shown that the subRELATIVISTIC limit presents new corrections that have not been considered in previous work. We discuss the conformal invariance of the MHD equations for a radiation-dominated fluid and different types of scaling of the fluid variables that are relevant for other equations of state when the bulk velocity is subRELATIVISTIC. In particular, we review the super-comoving coordinates that have been proposed for matter-dominated fluids and present this choice of coordinates for any equation of state. First-order fluid dynamics to include imperfect RELATIVISTIC fluids and the scaling of the transport coefficients with temperature in the early Universe are presented. We review the propagation of sound waves, Alfvén waves, and MAGNETosonic waves in the early Universe plasma. The Boris correction for RELATIVISTIC Alfvén speeds is presented and adapted for early Universe applications. This review is an extension, including new results, of part of the lectures presented at the minicourse "Simulations of Early Universe Magnetohydrodynamics" lectured by A. Roper Pol and J. Schober at EPFL, as part of the six-week program "Generation, evolution, and observations of cosmological MAGNETic fields" at the Bernoulli Center in May 2024.
[abstract 18 / 50] (score: 3) - Title: A new CIGALE module for modeling AGN emission linesAuthors: Hao Zhang, Patrice Theule, Veronique Buat, Denis Burgarella, Estelle Pons, Mederic Boquien,Comments:Subjects: astro-ph.GACreated: 2026-06-15; Updated: 2026-06-17; Datestamp: 2026-06-17
Aims. The increasing discovery of high-redshift AGNs in recent years imposes more stringent requirements on spectral analysis tools for deriving the properties of AGNs and their host galaxies from emission-line diagnostics. To address this need, we develop a new module for the popular SED-fitting tool Code Investigating GALaxy Emission (CIGALE), the [nebular_AGN] module, which enables the efficient and flexible simulation and fitting of emission lines originating from the broad-line regions (BLRs) and narrow-line regions (NLRs) of AGNs, and allows the estimation of the physical properties of these regions. Methods. We use the spectral synthesis code Cloudy to construct the database for the new module. Based on the X-ray and accretion disk continua implemented in CIGALE, we generate the incident radiation fields of the models. We then adopt the AGN geometry and dust settings implemented in CIGALE to define a flexible set of physical parameters for the gas clouds, thereby producing a comprehensive database for the [nebular_AGN] module. Results. We benchmark the [nebular_AGN] module using a QUASAR composite spectrum, an empirical metallicity calibration, and observational data from X-ray-selected AGNs. Our module can approximately reproduce the majority of QUASAR emission-line profiles, cover the key emission-line ratios observed in AGN samples, and provide an assessment of their physical properties. For specific combinations of parameters, the metallicity derived by our module is consistent with the empirical formula. We further compare our models with other photoionization models used to simulate AGN NLR emission, and perform a line-sensitivity study to identify the most effective diagnostic lines for each parameter in our module. Finally, we confirm that the dust attenuation law plays an important role in SED fitting.
[abstract 19 / 50] (score: 3) - Title: Constraints on Late-Time Flaring from Luminous Fast Blue Optical Transients using the Transiting Exoplanet Survey Satellite and the Zwicky Transient FacilityAuthors: Rahul Jayaraman, Anna Y. Q. Ho, Michael M. Fausnaugh, Eran Ofek, Daniel A. Perley, Ruslan Konno, Martti Kristiansen, Tracy X. Chen, Michael W. Coughlin, Steven L. Groom, George Helou, K. -Ryan Hinds, Mansi M. Kasliwal, Zoë McGrath, Josiah N. Purdum, Argyro Sasli, Jesper Sollerman,Comments: 23 pages (including references), 8 figures, 6 tables. Submitted to ApJSubjects: astro-ph.HECreated: 2026-06-15; Updated: 2026-06-17; Datestamp: 2026-06-17
The Luminous Fast Blue Optical Transient (LFBOT) AT2022tsd exhibited minutes-timescale optical flares in the tens of days following the initial transient event, likely due to a central engine -- either an accreting BLACK HOLE or a MAGNETar. In this paper, we use data from the Transiting Exoplanet Survey Satellite (TESS) and the Zwicky Transient Facility (ZTF) to constrain the occurrence of similar flares in the 12 (of 14) known LFBOTs that had observational coverage with TESS from tens of days to thousands of days after the transient's initial emission. We find seven flare-like signals at the locations of four unique LFBOTs; all seven can likely be attributed to a solar system object (SSO) moving through the TESS aperture. Assuming all seven flares arise from SSOs, for the LFBOT AT2024qfm we rule out flaring with a similar timescale (40--65 d) and luminosity ($νL_ν\sim10^{43}$ erg s$^{-1}$) as in AT2022tsd, while for AT2022tsd itself we rule out flares between 380--430 d after the initial transient that were as luminous as the earlier flares. This observation suggests that the engine power in AT2022tsd declined or shut off on a timescale of hundreds of days. We also find that there is no late-time activity detectable in TESS thousands of days after the prototype LFBOT, AT2018cow. We discuss our constraints on the duty cycle of such flaring and then present estimates for the number of minutes-duration flares detectable with ongoing and upcoming high-cadence ($\ll1$ d) wide-field surveys.
[abstract 20 / 50] (score: 3) - Title: Measurement of diJET transverse momentum imbalance and azimuthal acoplanarity in $p$+$p$ collisions at $\sqrt{s} = 200$ GeV with the sPHENIX detectorAuthors: sPHENIX Collaboration, M. I. Abdulhamid, U. Acharya, E. R. Adams, G. Adawi, I. Ahmed, C. A. Aidala, Y. Akiba, M. Alfred, S. Ali, A. Alsayegh, S. Altaf, H. Amedi, D. M. Anderson, V. V. Andrieux, A. Angerami, N. Applegate, M. U. Ashraf, H. Aso, S. Aune, B. Azmoun, V. R. Bailey, D. Baranyai, S. Bathe, A. Bazilevsky, S. Bela, R. Belmont, J. Bennett, J. C. Bernauer, J. Bertaux, R. Bi, A. Bonenfant, S. Boose, C. Borchers, H. Bossi, R. Botsford, R. Boucher, A. Brahma, J. W. Bryan, D. Cacace, I. Cali, M. Chamizo-Llatas, S. B. Chauhan, A. Chen, D. Chen, J. Chen, K. Chen, K. Y. Chen, K. Y. Cheng, C. -Y. Chi, M. Chiu, J. Clement, E. W. Cline, M. Connors, E. Cook, R. Corliss, Y. Corrales Morales, E. Croft, N. d'Hose, A. Dabas, D. Dacosta, M. Daradkeh, S. J. Das, A. P. Dash, G. David, C. T. Dean, K. Dehmelt, X. Dong, A. Drees, J. Driebeek, J. M. Durham, A. Enokizono, H. Enyo, J. Escobar Cepero, R. Esha, B. Fadem, R. Feder, K. Finnelli, D. Firak, D. S. Fitzgerald, L. V. Flores-Sanchez, A. Francisco, J. Frantz, A. Frawley, K. Fujiki, M. Fujiwara, B. Garcia, P. Garg, G. Garmire, E. Gentry, Y. Go, C. Goblin, I. Goel, W. Goodman, Y. Goto, A. Grabas, O. Grachov, J. Granato, N. Grau, S. V. Greene, S. K. Grossberndt, R. Guidolini-Cecato, T. Hachiya, J. S. Haggerty, R. Hamilton, J. Hammond, D. A. Hangal, T. Harada, S. Hasegawa, M. Hata, W. He, X. He, T. Hemmick, A. Hodges, M. E. Hoffmann, A. Holt, B. Hong, M. Housenga, S. Howell, Y. Hu, H. Z. Huang, J. Huang, T. C. Huang, D. A. Huffman, C. Hughes, J. Hwang, T. Ichino, M. Ikemoto, D. Imagawa, H. Imai, Y. Ishigaki, D. Jah, J. James, H. -R. Jheng, Y. Ji, Z. Ji, H. Jiang, M. Kano, L. Kasper, T. Kato, Y. Kawashima, A. M. Khan, M. S. Khan, T. Kikuchi, J. Kim, B. Kimelman, H. T. Klest, A. G. Knospe, M. B. Knuesel, H. S. Ko, J. Kuczewski, N. Kumar, R. Kunnawalkam Elayavalli, C. M. Kuo, J. Kvapil, Y. Kwon, J. Lajoie, J. D. Lang, A. Lebedev, S. Lee, L. Legnosky, S. Li, X. Li, T. Lian, S. Liechty, S. Lim, D. Lis, M. X. Liu, W. J. Llope, D. A. Loomis, R. -S. Lu, C. Ma, L. Ma, W. Ma, V. Mahaut, T. Majoros, I. Mandjavidze, E. Mannel, C. Markert, T. R. Marshall, C. Martin, H. Masuda, G. Mattson, M. Mazeikis, C. McGinn, E. McLaughlin, J. Mead, Y. Mei, T. Mengel, A. S. Menon, M. Meskowitz, J. Mills, A. Milov, C. Mironov, I. Mitrankov, M. Mitrankova, G. Mitsuka, N. Morimoto, M. Morita, D. Morrison, L. W. Mwibanda, C. -J. Naïm, J. L. Nagle, I. Nakagawa, Y. Nakamura, G. Nakano, Y. Namimoto, A. Narde, C. E. Nattrass, D. Neff, S. Nelson, D. Nemoto, P. A. Nieto-Marín, R. Nouicer, G. Nukazuka, E. O'Brien, G. Odyniec, S. Oh, V. A. Okorokov, A. C. Oliveira da Silva, I. Omae, J. D. Osborn, G. J. Ottino, Y. C. Ou, J. Ouellette, D. Padrazo, T. Pani, J. Park, A. Patton, H. Pereira Da Costa, D. V. Perepelitsa, M. Peters, S. Ping, C. Pinkenburg, R. Pisani, C. Platte, C. Pontieri, T. Protzman, M. L. Purschke, J. Putschke, R. J. Reed, L. Reeves, S. Regmi, B. Rehman, E. Renner, D. Richford, C. Riedl, T. Rinn, C. Roland, G. Roland, A. Romero Hernandez, M. Rosati, D. Roy, A. Saed, T. Sakaguchi, H. Sako, S. Salur, J. Sandhu, M. Sarsour, S. Sato, B. Sayki, C. Scarlett, B. Schaefer, J. Schambach, M. Schernau, R. Seidl, B. D. Seidlitz, Y. Sekiguchi, M. Shahid, D. M. Shangase, Z. Shi, M. Shibata, C. W. Shih, K. Shiina, M. Shimomura, R. Shishikura, E. Shulga, A. Sickles, D. Silvermyr, J. Singh, R. A. Soltz, W. Sondheim, I. Sourikova, P. Steinberg, D. Stewart, M. Stojanovic, S. Stoll, Y. Sugiyama, O. Suranyi, A. Suzuki, R. Takahama, W. -C. Tang, S. Tarafdar, E. Thorsland, T. Todoroki, L. S. Tsai, H. Tsujibata, M. Tsuruta, J. Tutterow, E. Tuttle, B. Ujvari, E. N. Umaka, M. Vandenbroucke, J. Vasquez, J. Velkovska, V. Verkest, A. Vijayakumar, X. Wang, Y. Wang, Z. Wang, I. S. Ward, M. Watanabe, J. Webb, A. Wehe, A. Wils, V. Wolfe, C. Woody, W. Xie, Y. Yamaguchi, Z. Ye, K. Yip, Z. You, G. Young, C. -J. Yu, X. Yu, X. Yu, W. A. Zajc, V. Zakharov, J. Zhang, C. Zimmerli,Comments: 19 pages total, 8 figures, 1 tables. All figures and tables can be found at https://www.sphenix.bnl.gov/PublicResults/sPH-JET-2026-01Subjects: nucl-exCreated: 2026-06-15; Updated: 2026-06-17; Datestamp: 2026-06-17
This Letter reports on measurements of diJET transverse momentum ($p_\mathrm{T}$) imbalance and azimuthal acoplanarity in proton-proton collisions at $\sqrt{s} = 200$~GeV, using data recorded by the sPHENIX detector at the Relativistic Heavy Ion Collider corresponding to an integrated luminosity of $41$~pb$^{-1}$. Jets are reconstructed using the anti-$k_t$ algorithm with radius parameters $R = 0.3$ to $0.8$ from electroMAGNETic and hadronic calorimeter energy deposits. The JET $p_\mathrm{T}$ resolution is determined directly in data using two independent methods. The diJET $p_\mathrm{T}$ imbalance is characterized by the ratio $x_\mathrm{J} = p_\mathrm{T,2}/p_\mathrm{T,1}$ where $p_\mathrm{T,1(2)}$ is the highest (second-highest) JET $p_\mathrm{T}$ in the event. The diJET azimuthal acoplanarity $Δϕ= |ϕ_1 - ϕ_2|$ is also reported. Results are reported for different $p_\mathrm{T,1}$ selections and JET radius parameters, normalized per diJET pair, and compared to the results of \textsc{Pythia} and \textsc{Herwig} Monte Carlo event generators. These measurements provide a stringent quantitative test of the modeling of QCD parton shower and hadronization dynamics, place important constraints on event-generator descriptions at RHIC energies, and establish a comprehensive proton-proton baseline for forthcoming measurements of JET modification in heavy ion collisions.
[abstract 21 / 50] (score: 3) - Title: Black Hole Stars Across the Universe: Identifying Central Engine Dominated Little Red Dots at $z\sim1.5-9.5$Authors: Andrea Weibel, Rohan P. Naidu, Pascal A. Oesch, Anna de Graaff, Raphael E. Hviding, Zhaoran Liu, Jorryt Matthee, Christina C. Williams, Gabriel Brammer, Alba Covelo Paz, Jenny E. Greene, Christian Kragh Jespersen, Zhiyuan Ji, Michael V. Maseda, David J. Setton, Wendy Q. Sun, Alberto Torralba, Callum Witten, Mengyuan Xiao,Comments: 37 pages, 27 figures, to be submitted to OJAp, catalog of BH*-dominated LRDs available at https://doi.org/10.5281/zenodo.20611334, we encourage community follow-upSubjects: astro-ph.GACreated: 2026-06-15; Updated: 2026-06-17; Datestamp: 2026-06-17
Photometric selections of Little Red Dots (LRDs) largely rely on identifying their ``V-shaped'' spectral energy distribution (SED). Recent work suggests this V-shape stems from a combination of a central engine -- also referred to as a Black Hole Star (BH*) -- and a star-forming host galaxy. We present a new and highly complementary photometric selection that is based on incorporating BH* templates in the \texttt{eazy} redshift fitting code. Selecting compact sources where a BH* template contributes $>80$\% to the best fitting SED in the rest-optical, we compile a sample of 241 BH*-dominated candidates from $\sim1000\,{\rm arcmin}^2$ of legacy and pure parallel JWST imaging. Our selection does not require a blue UV-component, and it successfully identifies objects that resemble the paradigmatic sources ``MoM-BH*-1'' and ``The Cliff''. We find that BH*-dominated sources exist across a wide range of redshifts ($z\sim1.7-9.3$) and optical luminosities (log$(L_{5100}/{\rm erg}\,{\rm s}^{-1})\sim42-44.5$), and we measure a median Balmer break strength of $\sim3$, with some breaks reaching values $>10$. We estimate bolometric luminosities in the range log$(L_{\rm bol}/{\rm erg}\,{\rm s}^{-1})\sim42-45$, which, assuming accretion at the Eddington-limit, would translate to BLACK HOLE masses of $M_{\rm BH}\sim10^4-10^7{\rm M_\odot}$, spanning the intermediate mass BLACK HOLE to the QUASAR regime. The number density of BH*-dominated candidates peaks at $z\sim5-6$ ($\sim10^{-5}\,{\rm Mpc}^{-3}$) and it declines by an order of magnitude down to $z\sim2$. Tentatively, comparing to V-shaped LRD samples suggests that the fraction of BH*-dominated sources among the broader LRD population does not decrease towards lower redshift. Crucially, our work demonstrates that BH*-dominated sources are not merely an early-Universe phenomenon but rather persist at least until cosmic noon.
[abstract 22 / 50] (score: 3) - Title: Reduced Effective Viscosity from Anisotropic Transport and Plasma Instabilities in the Sloshing Cores of Galaxy ClustersAuthors: John A. ZuHone, Stephen Majeski, Annie Heinrich, Alexander A. Schekochihin, Francisco Ley, Irina Zhuravleva,Comments: 30 pages, 18 figures, submitted to ApJSubjects: astro-ph.GA astro-ph.HECreated: 2026-06-16; Updated: 2026-06-17; Datestamp: 2026-06-17
The $\sim μ$G MAGNETic field in the intracluster medium (ICM) introduces a pressure anisotropy with respect to the MAGNETic field's direction that manifests as an anisotropic viscous stress. Plasma instabilities arising from the pressure anisotropy crossing certain thresholds force it to marginally stable values, reducing viscous transport. Additionally, the feedback of this anisotropic pressure on the velocity field has been predicted to lead to a form of self-organization that also can reduce viscous dissipation without affecting the collisionality. In this work, we present high-resolution Braginskii-MHD simulations of a galaxy cluster core with sloshing gas motions and turbulence, including the effects of anisotropic viscous stress and different simple prescriptions for limiting the pressure anisotropy due to plasma instabilities. Braginskii viscosity has an expected, though modest, effect on suppressing Kelvin-Helmholtz instabilities at sloshing cold front surfaces, dependent on how the pressure anisotropy is limited. Due to the sloshing motions, the MAGNETic field's strength can become high enough in places that the pressure anisotropy need not be limited. Nevertheless, the combined effect of the limiters and the turbulent structure of the MAGNETic field in all simulations is that the effective viscosity is much lower than the isotropic Spitzer value in a significant fraction of the core region. However, we find that this reduced viscosity is capable of steepening the velocity-amplitude spectrum and transferring a small fraction of the turbulent kinetic energy into heat. Finally, we present evidence for MAGNETo-immutable dynamics in our simulations.
[abstract 23 / 50] (score: 3) - Title: Kes 75 with IXPE: Detection of Nebular X-ray Polarization and Change in Pulsar LightcurveAuthors: Josephine Wong, Jack T. Dinsmore, Roger W. Romani, Stefano Silvestri, Shumeng Zhang, Ruolan Jin, Matteo Bachetti, C. Y. Ng, Niccolo Di Lalla, Wei Deng, Fei Xie, Patrick Slane, Niccolo Bucciantini, Philip Kaaret, Tsunefumi Mizuno, Maura Pilia, Yi-Jung Yang, Silvia Zane, Martin C. Weisskopf,Comments: 13+3 pages, 9 figures, 4 tables. Accepted for publication in ApJSubjects: astro-ph.HECreated: 2026-06-16; Updated: 2026-06-17; Datestamp: 2026-06-17
We present the first X-ray POLARIZATION measurements of the PSR/PWN complex within SNR Kes 75. Two $\rm {\sim}\,500\,ks$ IXPE observations were conducted in October/November 2024 and April 2025. The second observation yields a significant phase-average 2-8 keV POLARIZATION degree $\rm PD = 9.9\% \pm 2.5\%$ at $\rm PA=36.8^\circ \pm 7.3^\circ$, implying a toroidal field aligned with the PWN symmetry axis. The first epoch, however, has only a POLARIZATION upper limit. During this epoch, an additional pulsed component is visible at $Δϕ\approx 0.5$, detected at ${\sim}\,3.7σ$. An unbinned phase-resolved analysis reveals a high-PD rotating vector model PA sweep at the ${\sim}\,99.5\%$ confidence level, with angles fixed at those inferred from the PWN morphology; this can explain the loss of phase-average POLARIZATION. Additional observations are needed to pin down the nature of the anomalous pulse.
[abstract 24 / 50] (score: 3) - Title: A Semi-Analytical Loss Cone Theory for Tidal Disruption Event Rates Around Kerr Black HolesAuthors: Wenkang Xin,Comments: 68 pages, 6 figures. MMathPhys dissertation, University of Oxford, Trinity 2026Subjects: astro-ph.HE astro-ph.GA gr-qcCreated: 2026-06-16; Updated: 2026-06-17; Datestamp: 2026-06-17
A tidal disruption event (TDE) occurs when a star is scattered onto a near-radial orbit and is torn apart by a BLACK HOLE (BH)'s tidal field. The angular momentum threshold for disruption is set by general RELATIVISTIC tidal dynamics, while the supply of stars to the disruption zone is governed by Newtonian stellar dynamics. A spinning BH breaks the spherical symmetry of the disruption boundary, so a star's survival depends on both the magnitude and the orientation of its angular momentum. Existing treatments either assume a non-spinning BH or rely on numerical simulations of spinning BHs. We develop the first semi analytical framework that incorporates spin-dependent loss cone boundaries into TDE rate theory. Using a novel tidal tensor formalism, we compute inclination-dependent thresholds for tidal disruption and direct capture by the event horizon. We then revisit the classical one dimensional loss cone problem with nested disruption and capture boundaries, deriving a closed form capture fraction valid across all loss cone regimes. Finally, we formulate a two dimensional Fokker--Planck equation describing simultaneous diffusion in angular momentum magnitude and orientation. Through a perturbative treatment, we demonstrate that while the Kerr disruption boundary induces a first-order bias favouring the disruption of retrograde stars, the global TDE rate is remarkably insensitive to BLACK HOLE spin. This approach offers a tractable route to including spin and orbital inclination in population-level TDE studies.
[abstract 25 / 50] (score: 3) - Title: Ultra-High-Energy Cosmic Ray Boosted Relic NeutrinosAuthors: Jiajie Zhang, Jiajun Liao,Comments: 31 pages, 6 figuresSubjects: hep-ph astro-ph.HECreated: 2026-06-16; Updated: 2026-06-17; Datestamp: 2026-06-17
Ultra-high-energy COSMIC RAYs (UHECRs) can boost relic neutrinos to high energies through Standard Model (SM) neutral-current interactions, providing an indirect probe of the cosmic neutrino background (C$ν$B). In this work, we perform a systematic study of the diffuse UHECR-boosted C$ν$B flux including elastic neutrino-nucleon scattering (ES), coherent elastic neutrino-nucleus scattering (COH), incoherent neutrino-nucleus scattering (INCOH), baryon-resonance production (RES), and deep inelastic scattering (DIS). For the UHECR flux, we use mixed-composition spectra obtained from the UHECR propagation code PriNCe and from the H3a and H4a implementations of the Hillas model, together with SFR, QSO and GRB source evolution models. We find a clear hierarchy of scattering channels in boosted neutrino energy. The coherent scattering dominates at low-energy neutrino flux for heavy nuclear component, while ES and INCOH become important once individual nucleons are resolved. The RES channel gives a non-negligible contribution in the high-energy region, and DIS appears only at the highest energies and is most visible for the H4a models. Using current IceCube and Pierre Auger Observatory data, we derive upper limits on the C$ν$B overdensity. Our results show that reliable predictions of the UHECR-boosted C$ν$B signal require a combined treatment of the relevant SM scattering channels, UHECR composition, source evolution and the neutrino mass spectrum.
[abstract 26 / 50] (score: 3) - Title: Energy-energy correlators in p-Pb collisions at $\sqrt{s_{\rm NN}} = 5.02$ TeVAuthors: ALICE Collaboration,Comments: 25 pages, 7 captioned figures, authors from page 20, submitted to Phys. Rev. C, figures at http://alice-publications.web.cern.ch/node/13350Subjects: nucl-exCreated: 2026-06-16; Updated: 2026-06-17; Datestamp: 2026-06-17
This paper presents the first measurement of the two-point energy-energy correlator (EEC) inside charged-particle JETs in p-Pb collisions at $\sqrt{s_{\rm NN}} = 5.02$ TeV with the ALICE experiment. The two-point EEC, an infrared- and collinear-safe measure of angular energy flow within JETs, is used to probe both perturbative and non-perturbative stages of the JET evolution. The EEC is reported in 20-80 GeV/$c$ JETs in p-Pb collisions and compared to a measurement of the EEC in pp events at $\sqrt{s} = 5.02$ TeV. A modification is observed in the 20-40 GeV/$c$ interval, with an enhancement at large opening angles and a suppression at small angles relative to pp collisions. The dependence of this modification on JET transverse momentum, rapidity, and forward activity is investigated. These results provide new constraints on cold nuclear matter effects relevant for disentangling initial- and final-state contributions to JET-structure modifications. An understanding of these cold nuclear matter effects is also relevant for interpreting EEC measurements in heavy-ion collisions.
[abstract 27 / 50] (score: 3) - Title: A Joint Optimal Search for Gravitational Waves from Resolved and Unresolved Supermassive Binary Black Holes with Pulsar Timing ArraysAuthors: Boris Goncharov, Gabriela Sato-Polito, Xiaoming Bi, Matias Zaldarriaga,Comments:Subjects: astro-ph.HE astro-ph.IM gr-qcCreated: 2026-06-16; Updated: 2026-06-17; Datestamp: 2026-06-17
We introduce, from first principles, a joint model of the gravitational wave background (GWB) and brightest supermassive BLACK HOLE binary (SMBHB) sources that may be individually resolvable in Pulsar Timing Array (PTA) searches for gravitational waves. We propose the characteristic number of SMBHB sources, $N_{\rm c}$, as a detection statistic for the astrophysical origin of the GWB. We then demonstrate how the brightest SMBHBs assist in resolving $N_{\rm c}$. Applying our method to the simulated NANOGrav 15-year data, which replicates all aspects of real data's known noise, observations, and the inferred GWB power spectrum, we demonstrate direct astrophysical limits on the strain amplitude of individually resolvable SMBHBs. We find that 21 of 114 SMBHB candidates from ACTIVE GALACTIC NUCLEi observations are in tension with the NANOGrav's observations. In contrast, only one candidate is in tension with the NANOGrav data based on the upper limits reported in the original analysis. Constraining the Poisson-specific characteristic number of SMBHBs, $N_{\rm c}$, at ${\rm yr}^{-1}$, we outline implications for the population properties of SMBHBs. Based on our new model applied to the simulated NANOGrav data, we calculate the probability of detecting GWs from isolated SMBHB in the 15-year data to be 2\% at the ${\rm SNR}=5$ level. Our projection towards the expected NANOGrav 20-year data suggests an increase to 5\%. With this, we estimate the probability of finding an outlier with an SNR of 2 in the NANOGrav 20-year data to be $40\%$.
[abstract 28 / 50] (score: 2) - Title: Properties of current sheets in two-dimensional tearing-mediated incompressible MAGNETohydrodynamic turbulenceAuthors: Chen Shi, Marco Velli, Nikos Sioulas, Zijin Zhang,Comments:Subjects: astro-ph.SR physics.space-phCreated: 2026-06-15; Updated: 2026-06-17; Datestamp: 2026-06-17
It is well known that the nonlinear evolution of MAGNETohydrodynamic (MHD) turbulence generates current sheets. In the solar wind turbulence, current sheets are frequently observed and they are believed to be an important pathway for the turbulence energy to dissipate and heat the plasma. In this study, we perform a comprehensive analysis of current sheets in a high-resolution two-dimensional simulation of balanced, incompressible MHD turbulence. The simulation parameters are selected such that tearing mode instability is triggered and plasmoids are generated throughout the simulation domain. We develop an automated method to identify current sheets and accurately quantify their key parameters including thickness ($a$), length ($L$), and Lundquist number ($S$). Before the triggering of tearing instability, the current sheet lengths are mostly comparable to the energy injection scale. After the tearing mode onsets, smaller current sheets with lower Lundquist numbers are generated. While power-law scaling relations between $L$ and $a$ and between $a/L$ and $S$ are observed, no clear correlation is found between the upstream MAGNETic field strength and thickness $a$. Finally, although the turbulence energy shows anisotropy between the directions parallel and perpendicular to the local MAGNETic field increment, we do not observe a direct correspondence between the shape of the current sheets and that of the turbulence ``eddies.'' These results suggest that one needs to be cautious when applying the scale-dependent dynamic alignment model to the analysis of current sheets in MHD turbulence.
[abstract 29 / 50] (score: 2) - Title: Matter environments around BLACK HOLEs: geodesics, light rings, and ultracompact configurationsAuthors: Dylan S. Fonseca, Caio F. B. Macedo, Mateus Malato Corrêa, Diego Rubiera-Garcia,Comments: 19 pages, 8 figures, 2 tablesSubjects: gr-qc astro-ph.GACreated: 2026-06-16; Updated: 2026-06-17; Datestamp: 2026-06-17
Astrophysical BLACK HOLEs are invariably embedded in matter environments whose gravitational influence can alter key strong-field features of the spacetime. In this work, we investigate the impact of spherically symmetric dark-matter distributions on BLACK HOLE geometry, geodesic structure, and ringdown phenomenology. Modeling the surrounding matter through Einstein clusters, we construct self-consistent spacetimes for three widely used density profiles - the Hernquist, Navarro-Frenk-White (NFW), and Jaffe models - and examine how their near-horizon behavior modifies the location and stability of circular timelike and null geodesics, including the innermost stable circular orbit (ISCO) and light rings. In the low-compactness regime, we derive analytical expressions showing that environmental effects generically shift the ISCO inward and the principal light ring outward, leading to parametric deviations in their associated orbital frequencies and Lyapunov exponents. At higher compactness, we explore the emergence of additional light rings, marginally stable orbits, and secondary horizons, identifying the regions of parameter space in which these ultracompact configurations arise. Using time-domain evolutions of scalar perturbations, we demonstrate how such structures can imprint characteristic signatures on the ringdown signal, including long-lived trapped modes and echo-like modulations associated with multiple potential barriers. Our results provide a unified framework for assessing environmental effects around BLACK HOLEs and highlight the importance of matter-induced corrections for interpreting upcoming electroMAGNETic and gravitational-wave observations.
[abstract 30 / 50] (score: 2) - Title: Rethinking Resonance Detectability during Binary Neutron Star Inspiral: Accurate Mismatch Computations for Low-lying Dynamical TidesAuthors: Alberto Revilla-Peña, Ruxandra Bondarescu, Andrew P. Lundgren, Jordi Miralda-Escudé,Comments: 13 pages, 7 figures, Submitted to Physical Review DSubjects: gr-qc astro-ph.HE astro-ph.SRCreated: 2026-06-16; Updated: 2026-06-17; Datestamp: 2026-06-17
We compute deviations from observed gravitational wave signals, where the amplitude of the signal is unchanged. As an example, we consider the detectability of low lying dynamical tides in binary neutron star or neutron star BLACK HOLE mergers. Tidal forces can excite oscillatory modes of one or both of the stars in the binary when the orbital frequency of the binary system sweeps through the resonant mode frequency dissipating energy into the vibrational mode. The orbital energy loss to the vibrational mode extracts energy from the orbital motion, advancing the time to merger. The inspiral then continues with an excess phase and a time advance. Both will cause a mismatch when fitting to a system that has not gone through the resonance. To resolve this effect, we compute the mismatch for current and planned detectors using both a quasi-analytical approach that relies on the computation of moment integrals and an optimized version of the standard numerical match function. We conclude that detectability can occur for time advances of the order of 1 ms with advanced LVK detectors for an excess energy-flux that is a few percent of the gravitational wave emission. Our results contrast with previous work, which model this effect solely as a phase shift of the waveform or by using the difference in the number of cycles induced by the resonant behavior. We show that tidal resonance effects primarily cause a time advance of the merger, rather than a phase difference, and that the single-frequency approximation commonly used in the literature significantly overestimates the detectability of this effect.
[abstract 31 / 50] (score: 2) - Title: Adaptive ray tracing, image diagnostics, and photon ring signatures of rotating dark-matter-dressed BLACK HOLEsAuthors: Mohsen Fathi,Comments: 18 pages, 12 figures, 2 tablesSubjects: gr-qc astro-ph.CO astro-ph.HECreated: 2026-06-16; Updated: 2026-06-17; Datestamp: 2026-06-17
We study the optical appearance of rotating BLACK HOLEs embedded in DARK MATTER environments using a phenomenological ray tracing framework. Rather than focusing on a single geometry, we compare two effective rotating backgrounds obtained from static DARK MATTER sourced seed metrics: a regular Einasto-type BLACK HOLE and a cored-NFW BLACK HOLE. Kerr is used as the reference spacetime. We construct observer-screen images by numerical backward ray tracing and analyse the horizon structure, shadow boundary, lensing bands, transfer maps, and synthetic intensity distributions produced by a common semi-analytic accretion prescription. We also introduce simple image-level diagnostics, an angular-size confrontation with M87* and Sgr A*, and simplified visibility-amplitude diagnostics. These additions are not intended as an EHT fit, but as a controlled way to identify which observables are most affected by the DARK MATTER dressing. For the representative parameters considered here, the Einasto-supported geometry remains very close to Kerr, while the cored-NFW case produces a stronger redistribution of the image, with larger centroid displacement, stronger brightness asymmetry, an outward shift of the characteristic bright-ring scale, and a visible change in the normalized visibility amplitude. The results indicate that rotating dark-matter-dressed backgrounds can produce systematic image-domain and Fourier-domain deviations that are partially degenerate with spin, inclination, and emission modelling. The framework is lightweight and extensible, and provides a first step toward future GRRT and GRMHD studies of rotating BLACK HOLEs in DARK MATTER environments.
[abstract 32 / 50] (score: 2) - Title: Galaxy-cluster-stacked FERMI-LAT, part IV: $\sim70$ GeV WIMP annihilation linesAuthors: Uri Keshet,Comments: 21 pages, 5 figures, 5 tablesSubjects: astro-ph.HE astro-ph.CO hep-phCreated: 2026-06-15; Updated: 2026-06-17; Datestamp: 2026-06-17
The strongest constraints on the velocity-dependent ($p$-wave) annihilation of weakly interacting massive particle (WIMP) DARK MATTER were derived from the deep potential wells of galaxy clusters. Even weaker signals can be extracted from sufficient aggregated clusters, by cross-correlating $γ$-rays with large-scale structure tracers or stacking over extensive cluster catalogs. Three independent such analyses show a similar triad of emission lines in FERMI-LAT data, around 70, 40, and 13 GeV, emerging from featureless spectra in wide-sky regions upon cross-correlation with eROSITA maps, and in stacked MCXC, eROSITA, and DESI catalog clusters once boosted to the cluster frame. These lines fit the anticipated $χχ\toγγ$, $γZ$, and $γh$ annihilation channels of a $\sim70$ GeV WIMP $χ$, detected by composite matched filters at trial-corrected global $Z$-scores reaching $5.6σ$ (cross-correlations) and $2.3σ$ (stacking), with intrinsic $\sim10^{[-20,-19]}$ cm$^3$ s$^{-1}$ channel cross-sections. High-resolution spectra establish six lines and a broad (three-line) feature in total, naturally aligned with the anticipated nine channels of two cross-annihilating WIMPs of masses $67.3_{-0.1}^{+0.1}$ and $71.4_{-0.1}^{+0.2}$ GeV (profile-likelihood bounds; $_{-5\%}^{+3\%}$ systematic; $5.3σ$). The Galactic-center GeV excess is broadly consistent with the corresponding $χχ\to b\bar{b}$ continuum.
[abstract 33 / 50] (score: 2) - Title: Quantum fate of the Choptuik naked singularityAuthors: Chih-Hung Wu,Comments: 63 pages, 13 figuresSubjects: gr-qcCreated: 2026-06-15; Updated: 2026-06-17; Datestamp: 2026-06-17
Classical critical collapse provides a dynamical route from smooth initial data to a naked singularity, representing a sharper violation of predictability than ordinary BLACK HOLE singularities. We argue that this distinction is erased by quantum backreaction. Building on the semiclassical interior analysis, where quantum self-energy of the collapsing matter generates a universal growing mode and a finite mass gap, we study the exterior naked singularity region that determines global visibility in the Einstein-scalar system. We analyze controlled exterior models in both $2+1$ and $3+1$ dimensions. In the former, smooth matching and physical boundary conditions analytically select a vacuum POLARIZATION state, whose backreaction cloaks the classically naked region by a quantum trapped branch. In the latter, numerical horizon tracing shows that near a quantum-shifted threshold the exterior develops finite-mass marginally trapped surfaces rather than a zero-mass naked endpoint. These results suggest a global quantum picture in which the Choptuik naked singularity shares the fate of an ordinary BLACK HOLE singularity: quantum effects push the putative Cauchy horizon behind a quantum-generated horizon, thereby reducing the loss of predictability to the standard BLACK HOLE evaporation problem.
[abstract 34 / 50] (score: 2) - Title: Improving low-latency multi-messenger follow-up of neutron star-BLACK HOLE mergers with mode-by-mode filteringAuthors: Francesco Iacovelli, Digvijay Wadekar, Javier Roulet, Emanuele Berti, Alessandra Corsi,Comments: 5+5 pages, 5+3 figures. Comments welcome. A public implementation and example workflow are available at https://github.com/JayWadekar/flywheelSubjects: gr-qc astro-ph.HE astro-ph.IMCreated: 2026-06-15; Updated: 2026-06-17; Datestamp: 2026-06-17
Rapid parameter estimation for neutron star-BLACK HOLE (NSBH) mergers is essential for deciding whether, where, and how electroMAGNETic facilities should follow up gravitational-wave alerts. Current low-latency analyses typically use only the dominant quadrupole harmonic, leaving strong degeneracies among luminosity distance, inclination, and intrinsic binary parameters. We show that mode-by-mode filtering of the $(2,2)$, $(3,3)$, and $(4,4)$ signal-to-noise-ratio (SNR) time series enables low-latency marginalization over higher-order-mode information at a computational cost comparable to quadrupole-only analyses. Applied to simulated NSBH detections in a LIGO-Virgo network at design sensitivity, our method improves constraints on luminosity distance, viewing angle, localization volume, and source-frame secondary mass, thereby sharpening crucial estimates of electroMAGNETic detectability and host-galaxy association. We also validate the approach on public data for previously detected NSBH events, finding the largest improvement for the asymmetric, higher-SNR event GW190814.
[abstract 35 / 50] (score: 2) - Title: Chemical enrichment of the Perseus cluster core seen by XRISM/ResolveAuthors: XRISM Collaboration, Marc Audard, Hisamitsu Awaki, Ralf Ballhausen, Aya Bamba, Ehud Behar, Rozenn Boissay-Malaquin, Laura Brenneman, Gregory V. Brown, Lia Corrales, Elisa Costantini, Renata Cumbee, Maria Diaz Trigo, Chris Done, Tadayasu Dotani, Ken Ebisawa, Megan E. Eckart, Dominique Eckert, Satoshi Eguchi, Teruaki Enoto, Yuichiro Ezoe, Adam Foster, Ryuichi Fujimoto, Yutaka Fujita, Yasushi Fukazawa, Kotaro Fukushima, Akihiro Furuzawa, Luigi Gallo, Javier A. García, Liyi Gu, Matteo Guainazzi, Kouichi Hagino, Kenji Hamaguchi, Isamu Hatsukade, Katsuhiro Hayashi, Takayuki Hayashi, Natalie Hell, Edmund Hodges-Kluck, Ann Hornschemeier, Yuto Ichinohe, Daiki Ishi, Manabu Ishida, Kumi Ishikawa, Yoshitaka Ishisaki, Jelle Kaastra, Timothy Kallman, Erin Kara, Satoru Katsuda, Yoshiaki Kanemaru, Richard Kelley, Caroline Kilbourne, Shunji Kitamoto, Shogo Kobayashi, Takayoshi Kohmura, Aya Kubota, Maurice Leutenegger, Michael Loewenstein, Yoshitomo Maeda, Maxim Markevitch, Hironori Matsumoto, Kyoko Matsushita, Dan McCammon, Brian McNamara, François Mernier, Eric D. Miller, Jon M. Miller, Ikuyuki Mitsuishi, Misaki Mizumoto, Tsunefumi Mizuno, Koji Mori, Koji Mukai, Hiroshi Murakami, Richard Mushotzky, Hiroshi Nakajima, Kazuhiro Nakazawa, Jan-Uwe Ness, Kumiko Nobukawa, Masayoshi Nobukawa, Hirofumi Noda, Hirokazu Odaka, Shoji Ogawa, Anna Ogorzałek, Takashi Okajima, Naomi Ota, Stephane Paltani, Robert Petre, Paul Plucinsky, Frederick S. Porter, Katja Pottschmidt, Kosuke Sato, Toshiki Sato, Makoto Sawada, Hiromi Seta, Megumi Shidatsu, Aurora Simionescu, Randall Smith, Hiromasa Suzuki, Andrew Szymkowiak, Hiromitsu Takahashi, Mai Takeo, Toru Tamagawa, Keisuke Tamura, Takaaki Tanaka, Atsushi Tanimoto, Makoto Tashiro, Yukikatsu Terada, Yuichi Terashima, Yohko Tsuboi, Masahiro Tsujimoto, Hiroshi Tsunemi, Takeshi Tsuru, Ayşegül Tümer, Hiroyuki Uchida, Nagomi Uchida, Yuusuke Uchida, Hideki Uchiyama, Shutaro Ueda, Yoshihiro Ueda, Shinichiro Uno, Jacco Vink, Shin Watanabe, Brian J. Williams, Satoshi Yamada, Shinya Yamada, Hiroya Yamaguchi, Kazutaka Yamaoka, Noriko Yamasaki, Makoto Yamauchi, Shigeo Yamauchi, Tahir Yaqoob, Tomokage Yoneyama, Tessei Yoshida, Mihoko Yukita, Irina Zhuravleva, Elena Bellomi, Ian Drury, Annie Heinrich, Julie Hlavacek-Larrondo, Julian Meunier, Konstantinos Migkas, Lior Shefler, Phillip C. Stancil, Nhut Truong, Benjamin Vigneron, Congyao Zhang, John ZuHone,Comments: 16 pages, 10 figures. Accepted for publication in Astronomy & AstrophysicsSubjects: astro-ph.GA astro-ph.HECreated: 2026-06-15; Updated: 2026-06-17; Datestamp: 2026-06-17
The intracluster medium (ICM) is rich in chemical elements, produced by core-collapse (SNIcc) and Type Ia SUPERNOVAe (SNIa) over the last $\sim$12 Gyr. Whereas cluster outskirts are uniformly enriched with Fe at $\sim$0.3 solar - strongly suggesting that the gas had been pre-enriched during or before the assembly of galaxies into clusters, the Fe abundance is known to centrally increase in the core of relaxed clusters. The origin of these central Fe peaks however, as well as the apparent presence of mysterious drops previously reported in the very centre of a number of systems, remain to be clarified. In this paper, we address these two questions by measuring the spatial distribution of Fe and its relative Si/Fe, S/Fe, Ar/Fe, Ca/Fe, Cr/Fe, Mn/Fe, and Ni/Fe ratios in the X-ray bright, nearby Perseus cluster. We take advantage of the unprecedented spectral resolution ($\sim$5 eV) offered by the Resolve microcalorimeter on board XRISM, which observed four distinct pointings of Perseus out to $\sim$250 kpc ($\sim$0.2$r_{500}$) during its Performance Verification phase. Although the presence of an X-ray bright AGN challenges a precise quantification of absolute abundances in the very core, our baseline analysis rules out a strong drop with $>$2$σ$ confidence, at variance with previous CCD measurements. In addition, we find a remarkable spatial uniformity of X/Fe ratios, supporting the idea of negligible late SNIa enrichment from the brightest cluster galaxy NGC 1275. We also compare the overall chemical composition of the Perseus ICM with SNcc and SNIa nucleosynthesis yield models, finding that the co-existence of two separate SNIa enrichment channels is not needed to reproduce the ICM ratios satisfactorily.
[abstract 36 / 50] (score: 2) - Title: Hector Galaxy Survey: Optical IFU and Chandra Reveal a Low-Luminosity AGN Behind Extended LINER EmissionAuthors: Kyuseok Oh, Gabriella Quattropani, Pratyush Kumar Das, Minje Beom, Joon Hyeop Lee, Oğuzhan Çakır, Andrei Ristea, Hyunjin Jeong, Jiwon Chung, Michael J. Koss, Scott M. Croom, Mina Pak, Matt S. Owers, Sarah M. Sweet, Jong Chul Lee, Julia J. Bryant, Sree Oh, Jesse van de Sande, Peixin Zhu, Stefania Barsanti, Madusha L. P. Gunawardhana, Sujeeporn Tuntipong, Robert Content, Jon Lawrence, Ayoan Salim Sadman, Will Saunders, Barnaby Norris, Gurashish Singh Bhatia,Comments: Accepted for publication in ApJSubjects: astro-ph.GACreated: 2026-06-15; Updated: 2026-06-17; Datestamp: 2026-06-17
We present evidence that the Hector Galaxy Survey galaxy C901005481609968 ($z_{\rm cl}=0.0553$), which exhibits spatially extended LINER-like emission in optical integral-field spectroscopy (IFS), hosts a low-luminosity ACTIVE GALACTIC NUCLEus (LLAGN) that contributes substantially to its ionization budget. Although the galaxy is not selected as an AGN by mid-infrared AGN color criteria, archival Chandra data reveal a compact nuclear X-ray source with $\log L_{\rm X}\approx41.46$ erg/s, supporting the presence of an LLAGN. Spatially resolved emission-line diagnostics show LINER-like line ratios across most spaxels with $\mathrm{S/N} \geq 3$, while spatially resolved $τ$ maps ($τ\equiv Q_{\rm pAGB}/Q_{\rm req}$) indicate a widespread photon deficit ($\logτ<0$ over most of the mapped region), even under the most optimistic pAGB normalizations, the nuclear region remains at $τ< 1$. Line-ratio--kinematic tests find no evidence for shock-dominated excitation as the primary driver of the extended emission, although a localized or sub-dominant shock contribution cannot be ruled out with the present data. We use this galaxy as a pilot case because the combination of Hector IFS and an independent nuclear X-ray constraint provides a stringent validation of the spatially resolved photon-budget framework. Our results indicate that evolved stellar populations alone cannot account for the observed emission, that an additional nuclear ionizing source is required at least in the inner region, and that a weak LLAGN likely contributes to the ionizing budget, particularly in the inner region. Our results demonstrate that extended LINER-like emission can conceal a substantial LLAGN contribution even when traditional optical and infrared AGN indicators are weak, and that spatially resolved photon-budget tests combined with X-ray constraints can effectively reveal such hidden activity.
[abstract 37 / 50] (score: 2) - Title: QPO-like Signatures and Hydrodynamical Variability in Accretion around a JNW-type Compact Spacetime in Freund-Nambu Scalar-Tensor GravityAuthors: Orhan Donmez, M. Yousaf, G. Mustafa,Comments: 11 pages, 4 figures, 1 TableSubjects: astro-ph.HE gr-qcCreated: 2026-06-15; Updated: 2026-06-17; Datestamp: 2026-06-17
Scalar tensor theories of gravity provide a broad as well as physically rich extension of general theory of relativity by allowing the gravitational interaction to be mediated not only by the spacetime metric but also by scalar degrees of freedom. In this manuscript, we present a new exact solution in the Freund-Nambu scalar-tensor (FNST) gravity scenario, representing a nontrivial scalar-tensor generalization of the Janis-Newman-Winicour naked-singularity geometry, characterized by an additional coupling parameter q in the scalar sector. We also numerically solve the general RELATIVISTIC hydrodynamic equations in order to investigate the shock-cone mechanism formed by Bondi-Hoyle-Lyttleton accretion around this compact spacetime on the equatorial plane. We show that stronger scalar-tensor deviations modify the shock-cone morphology, significantly increase the amount of matter accumulated near the central compact object, and enhance the oscillatory behavior of the shock cone. The Lorentzian-like peaks obtained from the numerically computed power spectral density are interpreted as hydrodynamically generated QPO-like modes. These modes are driven by shock cone oscillations and by the compression and rarefaction of the plasma trapped inside the cone. Finally, for a compact object with mass parameter M = 10M_sun, the numerically extracted frequencies are found mainly in the range from a few Hz up to approximately 100 Hz. These frequencies overlap with the QPO ranges reported in stellar-mass black-hole-candidate systems. In particular, the frequencies obtained for the FNST2-FNST4 models fall within the range of timing features reported for the source GRS 1915+105. These results suggest that the exterior hydrodynamical variability of FNST compact spacetimes may provide phenomenological diagnostics of scalar-field-induced deviations from the Schwarzschild reference case.
[abstract 38 / 50] (score: 2) - Title: Exciting the Vacuum: Non-Thermal Particle Bursts and Multi-Messenger Signals from Binary Black HolesAuthors: Sohrab Rahvar,Comments: 9 pages, 2 figures, submitted to PRDSubjects: gr-qcCreated: 2026-06-15; Updated: 2026-06-17; Datestamp: 2026-06-17
We investigate particle production in the dynamical curved spacetime of a binary BLACK HOLE system. Particle production is a well-known feature of quantum field theory in curved spacetime, underlying the Hawking and Unruh effects. Here we extend it to the time-varying gravitational perturbation sourced by a binary BLACK HOLE. Treating a massless scalar field coupled to the binary metric, we compute the particle flux and radiated energy to leading order in the metric perturbation $h_{μν}$, using both the Bogoliubov transformation method and the S-matrix formalism. The perturbation is modeled with the standard quadrupole formalism, retaining the time-domain quadrupolar ($\ell=2$) contribution that dominates gravitational-wave emission. Our calculation is valid in the weak-field, large-separation inspiral regime and is not expected to capture the strong-field, nonlinear merger phase. In this regime we find a characteristic non-thermal, power-law emission with $dE/dt \propto M^{10/3}ω^{16/3}$, in contrast to a thermal Hawking spectrum. Extending the analysis through merger that uses the numerically-RELATIVISTIC metric is left to future work.
[abstract 39 / 50] (score: 2) - Title: Optical Emission Spectroscopy Measurements of keV Apparent Ion Temperatures in Avalanche Energy's Centrifugal Mirror MachineAuthors: M. Affolter, E. C. Hayes, A. Helson, E. McKee, A. Gargone, S. Hepner, R. Langtry,Comments: Technical ReportSubjects: physics.plasm-phCreated: 2026-06-15; Updated: 2026-06-17; Datestamp: 2026-06-17
Newly formed ions in $E \times B$ devices are rapidly accelerated by strong radial electric fields and execute large cycloidal orbits in the presence of an axial MAGNETic field. At locations where these orbits intersect, ions originating from different birth radii arrive with substantially different velocities, producing a non-Maxwellian velocity distribution with a large velocity variance. Through Coulomb collisions and collective interactions, this distribution relaxes toward a drifting Maxwellian in the rotating frame. Here, we present the first optical emission spectroscopy (OES) measurements of the line-of-sight-convolved ion-velocity distribution, from which an apparent ion temperature is determined, in Avalanche Energy's centrifugal mirror machine. High-resolution $H_α$ spectra obtained along five chordal lines-of-sight spanning the plasma radius are analyzed using two complementary models representing limiting cases of the ion dynamics: a collisionless cycloidal model based on the ion-velocity distribution arising from deterministic single-particle orbits, and a rotating Gaussian model based on collisions and collective processes that fully randomize the cycloidal motion into a drifting Maxwellian in the rotating frame. Combined, these approaches bracket the possible degree of velocity-space relaxation and provide a stringent test of the inferred ion energies. Both models reproduce the measured spectra relatively well and yield density-weighted apparent ion temperatures of $1.40\pm0.43$ keV for the rotating Gaussian model and $1.55\pm0.24$ keV for the cycloidal model. These results provide direct spectroscopic evidence that strong $E \times B$ rotation in a device only a few centimeters in size can generate ion populations with keV energy spreads.
[abstract 40 / 50] (score: 2) - Title: The properties of tidal disruption event infrared counterparts produced by dust rings and inference of the observing angleAuthors: Rob A. J. Eyles-Ferris,Comments: 8 pages, 7 figures, 2 tables. Accepted to MNRASSubjects: astro-ph.HECreated: 2026-06-15; Updated: 2026-06-17; Datestamp: 2026-06-17
A substantial fraction of tidal disruption events (TDEs), resulting from a BLACK HOLEs's disruption and accretion of a star, exhibit infrared (IR) counterparts thought to arise from spherical shells of dust reprocessing the TDE emission. Some modelling of TDEs also predicts an angular dependence in their observed properties with more X-ray emission on-axis and more optical emission at higher angles. However, there is growing evidence that X-ray rich TDEs are more likely to exhibit IR counterparts, contradicting the spherical shell model that predicts no significant variation in IR luminosity with angle. Here, I demonstrate that this result naturally follows for dust arranged in a ring instead of a spherical shell. I present a toy model of this scenario and show that on-axis angles result in a brighter counterpart. I also show that on-axis angles result in a delay in the initial rise and off-axis angles may display a double-peaked structure. Crucially, this model also allows the observing angle of the TDE to be constrained. Finally, I demonstrate that this model reproduces the properties of two IR counterparts, including constraining their observing angles and independently inferring an optical plateau, and briefly comment on its application to quasi-periodic eruption counterparts.
[abstract 41 / 50] (score: 2) - Title: Transformation of solar wind energy and helicity spectra in the frame of MAGNETohydrodynamics shell modelingAuthors: I. Dukanov, E. Yushkov, P. Frick, D. Sokoloff,Comments: Received 26 November, 2025 Revised 20 March, 2026 Accepted 16 April, 2026 Published 12 May, 2026Subjects: astro-ph.SRCreated: 2026-06-15; Updated: 2026-06-17; Datestamp: 2026-06-17
Based on the data recorded during the Parker Solar Probe mission, it can be suggested that there is no balance between kinetic and MAGNETic energy in the vicinity of the Sun. The spectra collected at different radial distances show an energy transfer from one component to another, followed by a change in inertial range slope and large-scale break shifted towards lower wavenumbers. Using the shell (cascade) modeling approach, we attempt to explain and understand this observed spectra transformation, considering a free-decay turbulence process and modeling a simple transition to a quasi-stationary equilibrium between the MAGNETic and kinetic energies. Varying the parameters of turbulence mirror asymmetry (helicity), we numerically simulate changes in spectral indices, large-scale shift position, and inertial range transformations, comparing our model results with spacecraft observations of solar wind turbulence. We present and discuss the chaotic nature of the spectral MAGNETic helicity distributions, as well as the fact that helicity can accumulate at large scales. The applicability of a simple MHD shell model to repeat the key features of solar wind turbulence dynamics offers wide possibilities for its further use.
[abstract 42 / 50] (score: 2) - Title: OQ~208: A New Fe~II Changing-look Active Galactic Nucleus and Implications for the Nature of the Changing-look PhenomenonAuthors: J. Wang, W. K. Zheng, D. W. Xu, T. G. Brink, C. Gao, A. V. Filippenko, Z. H. Yao, J. Y. Wei,Comments: 12 pages, 6 figures and 2 tables, accepted by ApJSubjects: astro-ph.GACreated: 2026-06-16; Updated: 2026-06-17; Datestamp: 2026-06-17
In addition to the traditional hydrogen Balmer emission lines, here we extend the optical changing-look (CL) phenomenon occurring in some ACTIVE GALACTIC NUCLEi (AGNs) to the optical FeII complex. Multiepoch spectroscopy allows to identify OQ~208, a local flat-spectrum radio source, as a new FeII CL-AGN owing to the disappearance of both its strong FeII complex (RFe $\equiv$ FeII/H$β=0.64$) and its Balmer broad-line emission on a timescale of $\sim14$\,yr. The simultaneous disappearance implies that in this object, both the FeII and Balmer emission come from the same region exposed to the ionizing continuum. We further identify an anticorrelation between the FeII strength and the continuum (and also Eddington ratio) during the CL events in dozens of CL-AGNs recently studied by Panda \& Sniegowska (2024), suggesting a negative response of RFe to both $L_{5100}$ and $L_{\mathrm{bol}}/L_{\mathrm{Edd}}$; this can be understood by the Comptonization process in a hot, optically thin accretion flow.
[abstract 43 / 50] (score: 2) - Title: Schrödinger equations and fluctuation theorems for collisionless plasma systemsAuthors: Hideo Sugama,Comments: 25 pages , 1 figureSubjects: physics.plasm-phCreated: 2026-06-16; Updated: 2026-06-17; Datestamp: 2026-06-17
The fluctuation theorem and detailed fluctuation theorem are formulated for classical systems whose governing equations can be written in Schrödinger-type equations and which possess either a unitary or an antiunitary time-reversal operator. The initial state vector is treated as a random variable drawn from a time-reversal-symmetric probability distribution, and a stochastic relative entropy defined from its probability density is used to formulate these theorems. The framework is applied to two collisionless plasma systems: the linear Vlasov-Poisson and linear gyrokinetic systems. For the linear Vlasov-Poisson system, the governing equations are recast into Schrödinger form, and Hamiltonian eigenvectors corresponding to Case-Van Kampen modes are derived to construct explicit solutions. The stochastic relative entropy is interpreted as entropy generation associated with Landau damping, in which electric-field energy is transferred from the lowest Hermite state to higher-order Hermite states acting as thermal reservoirs. For a specific class of initial distributions, a new analytical expression for the probability density function of the stochastic relative entropy is derived and validated numerically. For the linear gyrokinetic system in a uniform MAGNETic field, the governing equations are likewise transformed into Schrödinger form, and the corresponding time-reversal operators are identified. The state-vector space is constructed as a tensor product of species, perpendicular-velocity, and parallel-velocity spaces. The resulting state vectors decompose into two orthogonal components: one coupled to electroMAGNETic fluctuations and the other corresponding to ballistic modes. These results establish a nonequilibrium statistical-mechanical framework for collisionless plasma dynamics and provide useful examples for future quantum-computing applications to plasma simulations.
[abstract 44 / 50] (score: 2) - Title: Latent Residual-Closure Fourier Neural Operator for Robust Multi-Field Solving in Particle-in-Cell SimulationsAuthors: Jianhua Lyu, Linlin Zhong,Comments: 23 pages, 12 figures, 2 tablesSubjects: physics.comp-ph physics.plasm-phCreated: 2026-06-16; Updated: 2026-06-17; Datestamp: 2026-06-17
Particle-in-cell (PIC) simulations are widely used for kinetic plasma modeling in energy applications, but their efficiency is often limited by repeated field solves on dense meshes. This work proposes a Latent Residual-Closure Fourier Neural Operator (LRC-FNO) for robust surrogate multi-field solving in PIC simulations. Rather than treating field prediction as a purely data-driven regression task, LRC-FNO formulates PIC field solving as a two-level residual-closure problem involving source compression and source-to-field operator mapping. An autoencoder extracts compact representations of particle-deposited source fields, while a Latent Closure Refiner recovers unresolved residual structures lost during compression. A Coarse-FNO Solver captures the dominant field response, and a Residual-Closure FNO restores full-resolution corrections. The method is tested on three benchmarks with increasing complexity: 1D linear Landau damping (LLD), 2D two-stream instability (TSI), and a 2D scrape-off layer (SOL) fusion plasma model. In LLD and TSI, LRC-FNO better preserves charge-to-potential mapping, potential-mode evolution, residual charge structures, and particle-field energy exchange during closed-loop PIC integration. In the SOL case, LRC-FNO achieves relative L2 errors of 0.0447 for the self-consistent potential and 0.0251 for the MAGNETic vector potential in single-step prediction. More importantly, when used as a neural initial guess with 20 iterative corrections, LRC-FNO maintains strong physical consistency in extrapolated closed-loop simulations, preserving charge and current density structures over a time range close to twice the training horizon. These results demonstrate that LRC-FNO can serve as both a fast surrogate field solver and a high-quality initialization strategy for iterative PIC field solvers.
[abstract 45 / 50] (score: 2) - Title: Measurement of isolated photon plus two-JET correlations in Pb+Pb and $pp$ collisions at 5.02 TeV with ATLASAuthors: ATLAS Collaboration,Comments: 37 pages total, author list starting on page 20, 7 figures, submitted to Phys. Lett. B. All figures including auxiliary figures are available at http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HION-2023-03Subjects: nucl-exCreated: 2026-06-16; Updated: 2026-06-17; Datestamp: 2026-06-17
This paper presents a measurement of photon plus two-JET events in $pp$ and Pb+Pb collisions, i.e. events in which the transverse momentum of a single photon is balanced by two distinct JETs. The measurement was performed using $pp$ data taken in 2017 with an integrated luminosity 260 pb$^{-1}$, and Pb+Pb data taken in 2018 with an integrated luminosity 1.72 nb$^{-1}$, both at $\sqrt{s_\mathrm{NN}}$ =5.02 TeV, as recorded by the ATLAS detector. Events with photons in the transverse momentum range 90-180 GeV and at least two anti-$k_t$ $R = 0.2$ JETs with a $p_\mathrm{T}$ > 30 GeV are selected, and three observables are measured: ${\mathrm{x}}_{\mathrm{JJ}γ}$, $\mathrm{A}_{\mathrm{JJ}γ}$, and $ΔR_{\mathrm{JJ}}$. These observables characterise the overall energy loss of the multiparton system from medium interactions (${\mathrm{x}}_{\mathrm{JJ}γ}$), the relative energy loss between the two colour-charge carriers ($\mathrm{A}_{\mathrm{JJ}γ}$), and medium-induced modifications to their opening angle ($ΔR_{\mathrm{JJ}}$). The observables are corrected for uncorrelated combinatoric background contributions using a novel multiJET mixing technique, for photon purity, and for detector resolution effects via iterative unfolding. Final results are presented per photon, and the ratio ($I_\mathrm{AA}$) is taken between measurements in Pb+Pb and $pp$ collisions, for Pb+Pb centrality intervals of 30-80%, 10-30%, and 0-10%. Significant suppression of per photon two-JET yields in all three observables, $I_\mathrm{AA} < 1$, is observed as a result of parton-medium interactions. The experimental measurements are compared to three different JET quenching models: JEWEL, JETSCAPE, and LBT.
[abstract 46 / 50] (score: 2) - Title: High-energy Particle Transport in Three-dimensional Anisotropic Turbulent Magnetic FieldsAuthors: Daniela Maci, Rony Keppens, Fabio Bacchini,Comments:Subjects: physics.space-ph astro-ph.HE astro-ph.SR physics.flu-dynCreated: 2026-06-16; Updated: 2026-06-17; Datestamp: 2026-06-17
The understanding and modeling of high-energy particles transport in turbulent MAGNETic fields is an important open question in space- and astrophysics. The multiscale, nonlinear nature of turbulence, and the high variability of turbulence properties across different environments, make it particularly challenging to reach a full understanding of the interactions between particles and turbulent fluctuations. Using synthetic, realistically looking turbulent MAGNETic field realizations generated by the BxC toolkit, we investigate how the scattering of particles is affected by anisotropic fluctuations in strongly turbulent fields. We find evidence that, in the absence of a uniform background or guide MAGNETic field, the scattering process is not governed by the turbulence correlation length. We then further verify this hypothesis by studying particle transport in the presence of a guide field. We find evidence of a different scattering mechanism than the usual pitch-angle diffusion used to describe scattering in strong-guide-field settings.
[abstract 47 / 50] (score: 2) - Title: An atypical X-ray variability component in the BLACK HOLE candidate AT2019weyAuthors: Pengcheng Yang, Mariano Méndez, Sandeep K. Rout, Candela Bellavita, Federico García, Diego Altamirano, Ole König, Federico A. Fogantini,Comments: 12 pages, 6 figures, Accepted for publication in Astronomy & AstrophysicsSubjects: astro-ph.HECreated: 2026-06-16; Updated: 2026-06-17; Datestamp: 2026-06-17
Recent studies have revealed a notable timing feature in several BLACK HOLE X-ray binaries (BHXBs) during the soft-to-hard transition at the outburst decay. Within a narrow frequency range, the phase lags between high- and low-energy X-ray light curves exhibit a sudden increase, accompanied by a drop in the coherence function. These narrow features have been associated with a quasi-periodic oscillation (QPO) appearing only in the imaginary part of the cross spectrum (CS). This QPO remains undetected in the power density spectrum (PDS) and is known as imaginary QPO. Motivated by these results, we analyse five years of NICER observations of the BHXB AT2019wey during its low-hard state (LHS) and hard-intermediate state (HIMS). We find an imaginary QPO in the CS of AT2019wey, with similar characteristics as those found in other BHXBs, making AT2019wey the fifth BHXB in which such QPOs have been found. As the source hardens, the frequency of the imaginary QPO drops from $\sim$ 5 Hz to $\sim$ 1 Hz, while its phase lag rises from $\sim$ 0.3 rad to $\sim$ 0.7 rad during the HIMS and from $\sim$ 0.5 rad to $\sim$ 0.6 rad during the LHS. During the HIMS, the phase-lag energy spectrum of the imaginary QPO shows a typical U-shaped profile, while the shape changes in the LHS. The rms spectrum of the imaginary QPO rises below $\sim$ 2 keV, peaks at around $\sim$ 2 keV and decreases at higher energies, which may be associated with the presence of a relatively cool corona. We compare the properties of the imaginary QPO with those of the type-B and C QPOs in BHXBs and find a tentative connection to type-C QPOs. Combining the imaginary QPOs detected in AT2019wey with those reported in other sources, we find a systematic increase of QPO phase lags with QPO frequency. However, we cannot conclude whether the phase lags of imaginary QPOs exhibit the inclination dependence previously observed in type-C QPOs.
[abstract 48 / 50] (score: 2) - Title: MeV Gamma-Ray Lines from Radioactive Nuclei in Magnetar Giant FlaresAuthors: Wu-Zimo Qiumu, Meng-Hua Chen, Qiu-Hong Chen, Fei Xie, Hou-Jun Lv, Xiang-Gao Wang, En-Wei Liang,Comments: 12 pages, 6 figures, 2 tables. Accepted for publication in SCIENCE CHINA Physics, Mechanics & AstronomySubjects: astro-ph.HECreated: 2026-06-16; Updated: 2026-06-17; Datestamp: 2026-06-17
The rapid neutron-capture process (r-process) is widely regarded as the dominant mechanism responsible for the synthesis of heavy elements in the universe, yet its astrophysical sites remain an open question. Recent studies suggest that the high-entropy, rapidly expanding baryonic material ejected by MAGNETar giant flares may provide favorable conditions for r-process nucleosynthesis, while the late-time gamma-ray emission observed from the MAGNETar SGR 1806-20 offers direct observational support for this scenario. In this work, we perform nuclear reaction network simulations to investigate the nucleosynthesis yields of MAGNETar giant flares and to characterize the associated nuclear gamma-ray line emission arising from the radioactive decay of heavy nuclei. The nuclei synthesized in MAGNETar giant flares are found to be mainly distributed near the first and second r-process abundance peaks. Owing to this nuclide composition, the gamma-ray opacity is found to be strongly energy-dependent with the opacity in the keV band exceeding that in the MeV band by approximately three orders of magnitude. The nuclear gamma-ray emission is dominated by MeV photons at early times and gradually extends toward the sub-MeV and keV bands as time progresses, thereby offering a diagnostic of heavy element enrichment in the ejecta. The gamma-ray spectrum exhibits a peak near 1 MeV with major contributions from $^{88}$Kr and $^{92}$Sr, whose radioactive decays produce several bright gamma-ray lines with fluxes exceeding $\sim10^{-8}$ erg cm$^{-2}$ s$^{-1}$, making them the most promising lines for detection by MeV gamma-ray detectors. Because MAGNETar giant flares occur in the Galaxy at a rate roughly three orders of magnitude higher than neutron star mergers and their gamma-ray lines are accessible to current MeV instruments, they offer new and valuable science opportunities for MeV gamma-ray astronomy.
[abstract 49 / 50] (score: 2) - Title: Understanding and Quantifying Banana Coil Magnetic Fields and Forces for Enhanced OptimisationAuthors: Annika Zettl, Tobias Schuett, Sophia Henneberg,Comments:Subjects: physics.plasm-phCreated: 2026-06-16; Updated: 2026-06-17; Datestamp: 2026-06-17
The optimised tokamak-stellarator hybrid concept (Henneberg and Plunk 2024) has the potential to combine tokamak and stellarator advantages to achieve MAGNETically confined fusion. These compact quasi-axisymmetric designs can have a low aspect ratio and large plasma volume, good particle confinement, and relatively simple coils. Previous work showed that such MAGNETic configurations can in principle be reproduced by a single type of non-planar "banana coil" alongside the conventional tokamak coilset (Henneberg and Plunk 2025). In this work, we optimise banana coils while also considering engineering constraints beyond simple geometric measures. We quantify the characteristic geometries of force-optimised banana coils and the MAGNETic fields they generate, and analyse the mechanisms by which forces may be reduced through optimisation.
[abstract 50 / 50] (score: 2) - Title: The Chirp-Mass Ladder: A New Rung EmergesAuthors: Vaibhav Tiwari,Comments:Subjects: astro-ph.HECreated: 2026-06-16; Updated: 2026-06-17; Datestamp: 2026-06-17
The population of binary BLACK HOLEs (BBHs) observed through gravitational waves (GWs) now includes around 250 events with the release of GWTC-5.0, enabling more detailed studies. The inferred chirp-mass distribution shows prominent peaks at approximately $7.5M_{\odot}$, $14M_{\odot}$, and $27M_{\odot}$, where the locations of subsequent peaks increase by approximately a factor of two. A parsimonious explanation for this structured distribution is a hierarchical merger scenario, in which the first peak arises from mergers of BLACK HOLEs of stellar origin, and higher-mass peaks arise from repeated mergers. Notably, with the addition of new observations, an intermediate peak near $19M_{\odot}$ emerges. This feature had been anticipated in earlier work as a consequence of intergenerational mergers involving second- and third-generation (G) BLACK HOLEs, thereby highlighting the predictive power of the hierarchical-merger interpretation. Furthermore, two groups of $1G+2G$ mergers recently reported in separate studies can be understood as distinct rungs -- $1G+2G$ and $3G+4G$ -- within this hierarchical chirp-mass ladder, a unification that describes both spin transitions with a single mechanism. Although expected correlations between mass ratios and spins are observed in multiple events across the mass range, the lack of clear signatures across all rungs invites investigation into the role of hierarchical mergers in shaping the \ac{BBH} population.
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