Current date: 2026-09-15
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Datestamp limit: 2026-09-15 (0 days ago)
Created/updated limit: 2026-09-08 (7 days ago)
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Scoring abstracts
Number of records retrieved: 1300
Keyword score statistics
score 11 -- 1 abstracts
score 9 -- 2 abstracts
score 7 -- 1 abstracts
score 6 -- 6 abstracts
score 5 -- 5 abstracts
score 4 -- 7 abstracts
score 3 -- 10 abstracts
score 2 -- 30 abstracts
in total -- 62 abstracts
Articles that appeared on 2026-09-15
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[abstract 1 / 62] Wow! (score: 11)
- Title: An ALMA view of the Jet-Arc CO clouds toward the TeV $γ$-ray source HESS J1023-575 and Westerlund 2; Evidence for the footprints of microQUASAR JETs, the very powerful cosmic-ray accelerator in the Galactic diskAuthors: Yasuo Fukui, Kisetsu Tsuge, Hidetoshi Sano, G. R. Bhuvana, Rin I. Yamada, Ryoji Matsumoto, Yuta Asahina, Tsuyoshi Inoue, Tim Lukas Holch, Emma de Oña Wilhelmi,Comments: 6 pages, 3 figures, 1 table. Accepted for publication in PASJ as a LetterSubjects: astro-ph.HE astro-ph.GACreated: 2026-09-14; Updated: 2026-09-15; Datestamp: 2026-09-15
The TeV $γ$-ray source HESS J1023-575 (HESSJ 1023 hereafter) is one of the brightest H.E.S.S. sources near the young massive cluster Westerlund 2. HESS J1023 shows a remarkable positional alignment with the Jet and Arc CO clouds on its eastern and western sides over 170 pc length. We have carried out sub-pc scale observations of the CO clouds with ALMA and have discovered that the clouds consist of numerous thin filamentary features of $\sim$0.5 pc width and 10--20 pc length at distance of 7.5 kpc, which are well aligned with the Jet-Arc axis. Based on the MAGNETo-hydrodynamical model of microQUASAR JETs launched from {the center of the $γ$-ray source} HESS J1023-575, we present an interpretation that the thin filamentary clouds are the footprints of the microQUASAR JETs on the HI gas. The model also explains the dissimilar Jet vs. Arc clouds in terms of HI density difference on each side. By using the density of the CO and HI gas and the $γ$-ray luminosity, we have calculated the COSMIC RAY proton energy $W_{\rm p}$ to be 7$\times$10$^{48}$ erg under the hadronic scheme, which is ten times larger than those derived in the TeV $γ$-ray SNRs RX J1713.7-3946 and RX J0852.0-4622. It is likely that HESS~J1023 has been active over 1-10 Myr, which is significantly longer than the duration of COSMIC RAY acceleration of the SNRs. HESS~J1023 is therefore an outstanding source of COSMIC RAYs equivalent to at least 1000 SNRs, and is possibly the most powerful CR accelerator in the Galactic disk. A high energy compact source in HESS~J1023, which is likely a Myr-old BLACK HOLE or neutron star, remains veiled due to heavy extinction.
[abstract 2 / 62] Wow! (score: 9) - Title: X-ray Polarization Signatures from Comptonization by Magnetic Reconnection PlasmoidsAuthors: John Groger, Kun Hu, Henric Krawczynski,Comments: Published in ApJLSubjects: astro-ph.HECreated: 2026-09-12; Updated: 2026-09-15; Datestamp: 2026-09-15
Emission from X-ray binaries in the hard spectral state is dominated by high-energy radiation attributed to the Compton scattering of seed photons. The prevalent model of the Comptonization by hot electrons or pairs faces the problem of rapid radiative cooling of the emitting particles. A proposed alternative mechanism is the Comptonization by scattering off fast plasmoids formed during MAGNETic RECONNECTion. In this work, we simulate a simplified model of the plasmoid chain with Monte Carlo radiation transport and report on spectropolarimetric properties. We find that the Comptonization off trans-RELATIVISTIC bulk plasmoids is not only able to reproduce the 100 keV spectral cutoff, but furthermore produces X-rays that are above 1 keV strongly polarized perpendicular to the RECONNECTion layer. The POLARIZATION is stronger than that from the Comptonization by an isotropic hot plasma owing to the confinement of the motion of the scattering plasmoids in the plane of the RECONNECTion layer. The dependence of POLARIZATION on azimuthal viewing angle is discussed, along with possible locations for the plasmoid chain in an equatorial current sheet or the sheath of the BLACK HOLE's RELATIVISTIC JET.
[abstract 3 / 62] Wow! (score: 9) - Title: Optical spectroscopy of the VHE flat-spectrum radio QUASAR PKS 0903-57Authors: E. Kasai, P. Goldoni, C. Boisson, S. Pita, W. Max-Moerbeck, F. D'Ammando, B. Rajput, M. Backes,Comments: 6 pages, 2 figures, AfAS 2026 conferenceSubjects: astro-ph.HE astro-ph.COCreated: 2026-09-14; Updated: 2026-09-15; Datestamp: 2026-09-15
We report new optical spectroscopic results for the gamma-ray BLAZAR PKS~0903$-$57. The optical properties of this source have historically been complicated to establish, due to a bright foreground star separated from the BLAZAR by only 0.67$^{\prime\prime}$. During its strong high-energy (HE) and very high-energy (VHE) gamma-ray flaring period between 2020 and 2022, the Southern African Large Telescope and Very Large Telescope (VLT) took spectra of its optical counterpart. Photometric monitoring with the Rapid Eye Mount (REM) telescope complemented the observations. The observational results were inconclusive. A major improvement was achieved with a repeat of the VLT observations in 2024 using a 0.5$^{\prime\prime}$ slit under excellent seeing conditions. This led to the detection of five narrow emission features in the spectra, yielding a robust redshift measurement of $z$ = 0.2621 $\pm$ 0.0006. We also detected a broad symmetric H$α$ emission component with a full width at half maximum of 4020 $\pm$ 30 km/s in the spectra. Non-thermal JET emission was found to dominate the continuum, supporting the classification of PKS~0903$-$57 as a flat-spectrum radio QUASAR. Another interesting observation was a significant velocity displacement of $\sim$1500~km/s between the broad H$α$ line and its corresponding narrow line. Such a displacement may be associated with unusual dynamics in the broad-line region or accretion flow, a system containing two supermassive BLACK HOLEs, or a recoiling BLACK HOLE produced following a supermassive black-hole merger. Building on these results, we carried out additional VLT, REM, and \emph{SWIFT} observations towards the end of 2024 and during 2025. We present in this paper the preliminary results from the analysis of these new data.
[abstract 4 / 62] Wow! (score: 7) - Title: First Light of Neutron Star Mergers: Off-axis Cocoon Cooling X-ray Emission from Short Gamma-Ray Burst JetsAuthors: Jian-He Zheng, Wenbin Lu,Comments: 13 pages, 9 figures, submittedSubjects: astro-ph.HECreated: 2026-09-13; Updated: 2026-09-15; Datestamp: 2026-09-15
Neutron star mergers (NSMs) are confirmed gravitational wave sources. Identifying an early electroMAGNETic counterpart for these events is therefore crucial for rapid localization and multimessenger follow-up. However, the associated Gamma-Ray Bursts (GRBs) are highly collimated and are therefore easily missed by off-axis observers. An early, less beamed counterpart is essential for identifying the majority of mergers. In this Letter, we investigate the cooling emission from JET-driven cocoons produced by short GAMMA-RAY BURST JETs propagating through merger ejecta. We perform hydrodynamic simulations and radiative post-processing to calculate the early X-ray emission over a wide range of viewing angles. We find that the mildly RELATIVISTIC cocoon produces bright soft X-ray transients for off-axis observers, with luminosities of $10^{46-48}{\rm erg\,s^{-1}}$ and durations of a few to ten seconds. The X-ray spectra are quasi-thermal with characteristic temperatures of $0.1$--$1\,{\rm keV}$. For observers at $θ_{\rm v}=10^{\circ}$, the cocoon emission is detectable by Einstein Probe (EP) out to $z\simeq 0.3$. For nearby events like GW170817, it remains detectable up to $θ_{\rm v}\simeq 45^{\circ}$. The predicted detection rate for EP is $0.5\,{\rm yr^{-1}}$ in the canonical model. In future multimessenger campaigns, rapid UV/optical/IR follow-up of such X-ray triggers can subsequently identify the associated kilonova and JET afterglow emission, which will confirm the origin.
[abstract 5 / 62] Yes (score: 6) - Title: The Deep Newtonian Regime in Late-Time Blast Waves: Inevitable Transition and Distinct Flux SignaturesAuthors: Sk. Minhajur Rahaman, Jonathan Granot, Paz Beniamini,Comments: Accepted for publication in ApJSubjects: astro-ph.HECreated: 2026-09-13; Updated: 2026-09-15; Datestamp: 2026-09-15
In many astrophysical transients, outflows drive shocks into the ambient medium, accelerating electrons to non-thermal energy distributions that produce broadband SYNCHROTRON emission. At late times, even initially collimated RELATIVISTIC JETs evolve into quasi-spherical Newtonian blastwaves. As the shock decelerates, the post-shock internal energy per particle decreases; below a critical velocity $β_{\rm DN} \approx 0.2$, only a fraction $ξ_e < 1$ of electrons are accelerated to RELATIVISTIC energies, defining the deep Newtonian (DN) regime. We develop a unified analytic framework for SYNCHROTRON emission in this phase, applicable to both single-velocity and stratified ejecta. For GAMMA-RAY BURST afterglows in a uniform medium, the DN transition occurs at $t_{\rm DN} \approx 3.7\,E_{51}^{1/3} n_0^{-1/3}$~yr, yielding a shallower decay by $δα= 6(p-2)/5$ relative to standard Newtonian predictions. For kilonova remnants ($E_0 = 10^{50.5}$~erg, $M_{\rm ej} = 0.1\,M_\odot$), the DN phase begins prior to deceleration; neglecting it underestimates radio flux by factors of $\sim 3$--$5$ during coasting and even more thereafter. Magnetar-boosted remnants ($E \sim10^{52}$~erg) should reach $\sim$\,10\,--\,100\,$μ$Jy at 3~GHz at $\sim$\,40\;Mpc, though limits on GW170817 already disfavor a long-lived millisecond MAGNETar. In core-collapse SUPERNOVAe in a wind medium ($ρ\!\propto\!r^{-k}$), the peak luminosity remains constant during coasting, while $ν_{\rm pk} \propto t^{-1}$; for SN~2023ixf, we find $k = 1.29 \pm 0.14$. The DN spectral energy distribution typically satisfies $ν_m\!<\!ν_{\rm sa}\!<\!ν_c$, peaking at sub-GHz frequencies where LOFAR and SKA-low are most sensitive. Even non-detections place robust constraints on ambient density and outflow energetics.
[abstract 6 / 62] Yes (score: 6) - Title: Little Red Dots as Supermassive Counterparts of SS 433: A Hyper-Eddington Accretion FrameworkAuthors: Shuying Zhou, Mouyuan Sun, Xihan Ji, Ya-Ping Li, Luis C. Ho, Roberto Maiolino, Zhen-Yi Cai, Hai-Cheng Feng, Manqi Fu, Wei-Min Gu, Tong Liu, Junfeng Wang, Jianfeng Wu, Yongquan Xue,Comments: 24 pages, 10 figures, accepted by ApJ; the model SEDs in Figure 4 are included in the arXiv source fileSubjects: astro-ph.HE astro-ph.GACreated: 2026-09-14; Updated: 2026-09-15; Datestamp: 2026-09-15
High-redshift little red dots (LRDs) are compact sources characterized by V-shaped spectral energy distributions (SEDs), broad emission lines, and often prominent Balmer breaks. Their high number density and apparently large BLACK HOLE masses suggest that they are essential to the early evolution of galaxies and supermassive BLACK HOLEs (SMBHs); however, the nature of their central engines remains uncertain. Here, we propose that LRDs are the supermassive, high-redshift counterparts of the hyper-Eddington accreting Galactic microQUASAR SS~433, viewed at high inclinations. By scaling the hyper-Eddington accretion physics from stellar-mass BLACK HOLEs to supermassive scales, we show that the observed LRD features, including X-ray weakness, soft optical SEDs, apparent sub-Eddington accretion ratio, and Balmer breaks, emerge naturally from the self-shielding geometry of a puffed-up accretion disk. In this framework, the broad-line regions are ionized by anisotropic radiation escaping from the inner disk, analogous to the unseen UV/X-ray emission revealed by the W50 nebula in SS 433. Their low-inclination or lower-accretion-rate counterparts would appear as little blue dots (LBDs) or normal ACTIVE GALACTIC NUCLEi. Our model predicts that the Balmer break strength positively correlates with the broad-line width, that the emission lines are more variable than the optical continuum, that LRDs are intrinsically more luminous than observed, and that LBDs are more variable than LRDs. This unified-scale model redefines LRDs as the essential laboratories for observing the rapid accretion-driven growth that shaped the early assembly of galaxies and their central SMBHs.
[abstract 7 / 62] Yes (score: 6) - Title: High-energy spectral cutoffs in the prompt emission of FERMI GAMMA-RAY BURSTs: bulk Lorentz factors, emission radii, and a cutoff-peak energy relationAuthors: Yuan-Yuan Zuo, Yuan-Chuan Zou,Comments: 35 pages, 9 figures, 3 tables, including appendicesSubjects: astro-ph.HECreated: 2026-09-13; Updated: 2026-09-15; Datestamp: 2026-09-15
The high-energy end of the GAMMA-RAY BURST (GRB) prompt spectrum carries information on the physical conditions of the RELATIVISTIC outflow, but the number of well-characterized spectral cutoffs is small. We present a systematic search for high-energy spectral cutoffs in the time-integrated prompt spectra of 139 GRBs observed by FERMI between 2008 July and 2025 December, selected to have broadband coverage either through a LAT detection or through bright BGO emission. Joint GBM, LLE, and LAT spectra over $T_{90}$ are fitted with four empirical models and compared using the Bayesian information criterion, yielding 106 bursts with well-constrained cutoff energies $E_c$. An empirical two-component Gaussian mixture model applied to $\log_{10}(E_c/\mathrm{MeV})$ separates a low-$E_c$ group from the main distribution at $E_c=2.12$ MeV; the 77 bursts lying firmly above this boundary are interpreted within the internal $γγ$ pair-opacity framework. Combining $E_c$ with wavelet-based minimum variability timescales (median $0.119$ s), we infer bulk Lorentz factors of $11.7$ to $2.78\times10^{3}$ (median 145) and emission radii of $\sim10^{13}$ to $10^{15}\,\mathrm{cm}$. Neither the $Γ$-$L_{\mathrm{iso}}$ nor the $Γ$-$E_{\mathrm{iso}}$ relation is statistically significant for the full sample, whereas the 27 bursts with measured redshifts show a moderate $Γ$-$L_{\mathrm{iso}}$ correlation with a slope of $0.36_{-0.23}^{+0.22}$. We further find a strong rest-frame correlation between the cutoff and peak energies, $E_{c,z}\propto E_{p,z}^{2.15_{-0.97}^{+0.96}}$, for the 26 bursts with measured redshifts, which persists after controlling for redshift.
[abstract 8 / 62] Yes (score: 6) - Title: Measurement of Cosmic-Ray Density in the Spiral Arms toward Galactic AnticenterAuthors: Jia-hao Liu, Bing Liu, Rui-zhi Yang,Comments: 12 pages, 4 figures, published in APJSubjects: astro-ph.HECreated: 2026-09-14; Updated: 2026-09-15; Datestamp: 2026-09-15
Using nearly 17 years of FERMI-LAT data, we analyzed the diffuse gamma-ray emission associated with different spiral arms of the Milky Way in the ranges $l = 105^\circ$ to $145^\circ$ and $b = -5^\circ$ to $5^\circ$. The gamma-ray emissions from these spiral arms all exhibited clear pion-bump features, which can be well explained by a power-law spectrum of cosmic-ray protons. The spectral indices corresponding to the three distinct spiral arms -- the Local Arm, the Perseus Arm, and the Outer Arm -- are found to be approximately $-2.75$, $-2.55$, and $-2.80$, respectively. The energy densities of the COSMIC RAYs above 10 GeV are estimated to be all around 0.2$\rm~eV~cm^{-3}$. We further compared our results with previous studies, which have established various propagation models predicting that COSMIC RAY density decreases and spectra soften with increasing Galactocentric radius. We found higher densities and harder spectral indices than predicted in the outer Galaxy, suggesting possible contributions from a larger halo, slower MAGNETic field decay, or a combination of these and other effects. In particular, the spectral hardening observed in the Perseus Arm may be attributed to locally enhanced cosmic-ray acceleration.
[abstract 9 / 62] Yes (score: 6) - Title: Spectro-polarimetric study of the BLACK HOLE X-ray binary SWIFT J1727.8-1613 in the JED-SAD frameworkAuthors: R. Muhammad, P. -O. Petrucci, W. Zhang, J. Ferreira, R. Belmont, J. Malzac, G. Marcel, G. Matt, M. Parra, T. Bouchet, N. Barnier, M. Clavel, G. Henri,Comments: 15 pagesSubjects: astro-ph.HECreated: 2026-09-14; Updated: 2026-09-15; Datestamp: 2026-09-15
Context. SWIFT J1727.8-1613 is an X-ray binary observed during its 2023-2024 outburst, including bright and dim hard states with similar X-ray polarimetric signatures but fluxes differing by two orders of magnitude. Aims. We aim to reproduce the spectro-polarimetric properties of these two hard states. Methods. We modelled their spectra in the JED-SAD framework and computed the X-ray polarisation properties of the best-fit configurations with the MONK general RELATIVISTIC radiative transfer code. Results. Both spectra are well reproduced within the JED-SAD framework, although the dominant radiative process differs: self-Comptonised bremsstrahlung in the bright state and self-Comptonised SYNCHROTRON in the dim state. In the bright state, the simulated polarisation fraction remains below the observed value of about 4%, while the polarisation angle differs from the observations by 90 degrees because of the JED's large vertical optical depth. In contrast, the dim state's simulated polarisation fraction is about 3% and its polarisation angle is perpendicular to the disk, both broadly consistent with IXPE measurements. The dim-state results are largely insensitive to the MAGNETic field configuration because of Faraday depolarisation. Conclusions. The dim hard state's spectro-polarimetric properties are well reproduced, whereas those of the bright state are not. We discuss a non-thermal particle distribution and electron scattering in an accretion-disk wind as possible explanations for the observed bright-state polarisation.
[abstract 10 / 62] Yes (score: 6) - Title: Magnetic Reconnection Heating of Thin Accretion Disks around Kerr Black HolesAuthors: Zhen Li,Comments: 12 pages, 4 figuresSubjects: gr-qc astro-ph.HECreated: 2026-09-14; Updated: 2026-09-15; Datestamp: 2026-09-15
The MAGNETic RECONNECTion process near a BLACK HOLE can efficiently convert MAGNETic energy into the kinetic and thermal energy of plasma outflows, enabling the extraction of rotational energy from a spinning BLACK HOLE. However, its impact on the surrounding accretion disk remains insufficiently explored. In this work, we develop a framework to investigate the 'heating' effect of MAGNETic RECONNECTion outflow plasma on thin accretion disks around Kerr BLACK HOLEs. We incorporate the energy and angular momentum fluxes of RECONNECTion outflow into the disk conservation laws as additional source terms, yielding a modified radiative flux. We investigate the dependence of the modified radiative flux on the BLACK HOLE spin, RECONNECTion radius, plasma MAGNETization, and outflow orientation. For a fixed MAGNETic field prescription, the contribution of the RECONNECTion outflow plasma to the modified radiative flux decreases as the BLACK HOLE spin increases. Its dependence on the RECONNECTion radius differs inside and outside the ergosphere: inside, a smaller radius enhances disk heating through more efficient extraction of BLACK HOLE rotational energy, whereas outside, a larger radius produces stronger heating due to reduced radial dilution of the outflow. The RECONNECTion outflow plasma contribution also increases with plasma MAGNETization and the radial component of the outflow velocity. Our results demonstrate that MAGNETic RECONNECTion can provide an additional source of energy and angular momentum for RELATIVISTIC accretion disks, establishing a connection between plasma processes near rotating BLACK HOLEs and the observable accretion disk properties, providing a new perspective on the strong gravitational field regime.
[abstract 11 / 62] Yes (score: 5) - Title: Local relaxation and scale-dependent alignment in compressible, MAGNETized turbulenceAuthors: James R. Beattie, Amitava Bhattacharjee,Comments: 6 pages including acknowledgments, 3 main figures; 14 pages total, including Supplemental Material with 2 figures. Accepted in PRLSubjects: physics.plasm-ph astro-ph.GA nlin.CD physics.flu-dynCreated: 2026-09-12; Updated: 2026-09-15; Datestamp: 2026-09-15
Driven net- and no-net-flux MHD turbulence simulations up to $10,\!368^3$ reveal sign-mixed velocity--MAGNETic, velocity--vorticity, and MAGNETic--current aligned patches below the energy equipartition scale. The first two angles scale as $λ^{1/8}$ and $λ^{1/16}$, while the third angle varies weakly with scale. We develop and test a constant-flux transport model for departures from relaxed states, which predicts both exponents. These findings affect eddy anisotropy, RECONNECTion-mediated turbulence onset, large-scale dynamos, and the nature of MAGNETized turbulence.
[abstract 12 / 62] Yes (score: 5) - Title: Tidal Disruption of Blanets by Supermassive Black Holes: From Test Particles to Planetary-Mass Bodies in Kerr SpacetimeAuthors: Shreesham Pandey, Sunita Singh,Comments: 21 pages, 5 figures. Revised manuscript; corrected numerical estimatesSubjects: astro-ph.HE astro-ph.EP astro-ph.SR gr-qcCreated: 2026-09-14; Updated: 2026-09-15; Datestamp: 2026-09-15
Planetary-mass bodies formed in ACTIVE GALACTIC NUCLEus (AGN) discs, termed "blanets", may undergo tidal disruption by the central supermassive BLACK HOLE (SMBH). We analyse this process in Kerr spacetime using Mino-time geodesics and the Marck tidal tensor in a parallel-transported tetrad, treating the blanet as a test particle with finite size entering through the disruption criterion. For a blanet of $100 M_{\oplus}$ and $6 R_{\oplus}$ around a $10^7 M_{\odot}$ SMBH, the tidal radius is 0.82 AU, or 8.3 gravitational radii, requiring a non-perturbative RELATIVISTIC treatment. The Hills mass depends on bulk density as $M_{\rm Hills}\proptoρ_p^{-1/2}$ and is independent of blanet mass at fixed density. Rocky compositions yield a lower Hills mass than a Sun-like star, while volatile-rich compositions yield a higher value, suggesting a potential composition diagnostic. The frozen-in fallback model gives a peak time of about 15 yr and a peak luminosity of $3.7\times10^{40}$ erg/s, about $3\times10^{-5}$ of the Eddington luminosity, predicting a faint, ultraviolet-peaked transient lasting roughly a century. Scalar resonant relaxation in the surrounding nuclear star cluster may deliver blanets to disruptive orbits over $10^8$ to $10^9$ yr, implying an estimated per-AGN event rate of $10^{-7}$ to $10^{-6}$ per year. Gravitational waves from sub-Earth-mass debris fragments remain approximately nine orders of magnitude below Laser Interferometer Space Antenna sensitivity.
[abstract 13 / 62] Yes (score: 5) - Title: Spinning Between Models: Continuum and Reflection Constraints in the Intermediate States of GRS 1716-249 and GRS 1739-278Authors: Tiffany Tausch, Paul A. Draghis, Erin Kara, Abderahmen Zoghbi, Laura Brenneman, Anna Ogorzalek, John A. Tomsick, Mark Reynolds, Javier Garcia, Riley Connors,Comments: 12 pages plus appendices. 8 figures, 5 tables. To be submitted to the Open Journal of AstrophysicsSubjects: astro-ph.HECreated: 2026-09-11; Updated: 2026-09-15; Datestamp: 2026-09-15
Measurements of stellar-mass BLACK HOLE spin probe accretion under strong gravity and constrain BLACK HOLE formation and evolution. Intermediate states, in which thermal disk, coronal, and reflection emission all contribute significantly, are particularly complex environments for spin measurements and useful for probing spectral-modeling systematics. We investigate these effects using paired, non-simultaneous SWIFT/XRT and NUSTAR observations of GRS 1716-249 and GRS 1739-278. We jointly model the spectra with kerrbb and relxillCp, linking or separately varying their spin parameters, and explore the parameter space with a Markov Chain Monte Carlo analysis. Within the adopted model, GRS 1716 strongly favors a high spin, whereas the GRS 1739 data allow high- and low-spin solutions with nearly identical fit statistics. Parameter-stepping experiments show that coordinated changes among parameters allow substantially different physical configurations to produce nearly indistinguishable spectra. For these datasets and within the adopted model, energy-band tests show that the Fe band provides the strongest direct sensitivity to the inferred spin, while the Compton hump helps constrain reflection parameters and the soft X-ray band characterizes the underlying continuum. When both the disk continuum and reflection components are adequately constrained, their associated spin parameters can favor a common solution within the joint model. With weaker constraints, the model permits statistically comparable solutions spanning nearly the full range of spins. Robust joint continuum and reflection spin inference requires broadband coverage, independent binary constraints, physically self-consistent models, and thorough exploration of parameter space.
[abstract 14 / 62] Yes (score: 5) - Title: The LGRBs Redshift and Jet Opening Angle Distributions and the Hubble Constant $H_0$Authors: Truong Le, Joseph Chromicz,Comments: 25 pages, 43 figures, accepted for publication in MNRAS, fixing tables layoutSubjects: astro-ph.HECreated: 2026-09-13; Updated: 2026-09-15; Datestamp: 2026-09-15
Using the SWIFT-Perley sample, Le, Ratke, & Mehta performed a study of the rate density of LGRBs with an assumed broken power-law GRB spectrum. They obtained a GRB-burst-rate functional form that fits the preSWIFT~and SWIFT~redshift cumulative distributions at all redshifts with an assumed Hubble constant of $H_0 = 72 \, {\rm km \, s^{-1} \, Mpc^{-1}}$. Further analysis indicated that the cumulative redshift distribution is weakly sensitive to variations in the Hubble constant $H_0$, whereas the corresponding differential burst-rate distribution exhibits greater sensitivity. In this paper, we extend this analysis by comparing model predictions for different values of $H_0$ with the observed cumulative and differential redshift and JET-opening angle distributions, while adopting the same GRB framework and observational samples. We find that both the cumulative and differential distributions depend only weakly on variations in $H_0$, and the model predictions using $H_0 \approx 68 - 80 \, {\rm km \, s^{-1} \, Mpc^{-1}}$ provide agreement with the observed LGRB distributions.
[abstract 15 / 62] Yes (score: 5) - Title: Ion-Acoustic-Like Modes in Ion-Loaded Pulsar-Wind Current Sheets: A Pressure-Balanced Existence CriterionAuthors: Manpreet Singh, Ripin Kohli, Siming Liu,Comments: 20 pages, 5 figuresSubjects: physics.plasm-phCreated: 2026-09-13; Updated: 2026-09-15; Datestamp: 2026-09-15
Pulsar wind electron--positron plasma lacks the heavy inertial species required for the conventional ion-acoustic-like compressive modes. However, if ions are mixed into the RECONNECTing striped-wind current sheet, a low-frequency compressive branch can appear. We develop a local, comoving-frame theory for such ion-acoustic-like modes in an ion-loaded, pressure-balanced pulsar-wind current sheet. The background model connects directly to pulsar observables through the light-cylinder MAGNETic field and Goldreich--Julian density, while the sheet structure is represented by a Harris-like field reversal and species-dependent compression factors. The pair species are treated as inertialess thermodynamic shielding populations, whereas the ions are described by a warm, nonRELATIVISTIC, MAGNETized fluid. Pressure balance fixes the pair and ion temperatures rather than prescribing them freely. This gives a closed expression for the pair-shielded ion-acoustic speed in terms of pulsar spin parameters. We derive the warm-ion electrostatic dispersion relation and discuss the conditions under which the ion-acoustic-like branch can exist in such a current sheet. We find that the ion-acoustic-like mode does not occur for all sheet parameters but is restricted to specific regions of parameter space. Thus, ion loading alone is not sufficient to sustain the mode; the local current-sheet conditions determine where an admissible ion-acoustic-like mode can exist. Consequently, any wave-driven anomalous dissipation or particle heating mediated by this mode must be highly localized rather than distributed uniformly across the striped wind. This framework provide the physical domain where the mode can exist, providing the necessary foundation for future studies of kinetic excitation and damping.
[abstract 16 / 62] Yes (score: 4) - Title: The Loud Tail of the Supermassive Black Hole Binary Population: Multimessenger Candidates and Prospects for SKAOAuthors: Juhan Raidal, Ville Vaskonen, Juan Urrutia, Hardi Veermäe,Comments: 13 pages, 6 figuresSubjects: astro-ph.CO astro-ph.HE gr-qcCreated: 2026-09-11; Updated: 2026-09-15; Datestamp: 2026-09-15
We assess whether electroMAGNETically identified supermassive BLACK HOLE (SMBH) binary candidates populate the rare, high-amplitude tail of the gravitational wave (GW) amplitude distribution. Using an SMBH binary population model fitted to the NANOGrav 15-year data, we find that 3C~66B and Mrk~501 are likely to stand out from the GW background, making them promising targets for individual-source searches. Furthermore, we show that individual detections can probe the binary hardening mechanism, as models with strong environmental hardening predict a higher abundance of individually resolvable binaries than purely GW-driven models. Applying the same population fits and accounting for the confusion noise from the unresolved population, we forecast that the Square Kilometre Array Observatory (SKAO) will resolve tens of individual binaries, with 3C~66B robustly detectable.
[abstract 17 / 62] Yes (score: 4) - Title: Evolution of the High-Energy Excess in SWIFT J1727.8-1613 during Its 2023 Flare StateAuthors: Xiao Fan, Bei You, Yi Long, Han He, Liang Chen,Comments: submitted to ApJSubjects: astro-ph.HECreated: 2026-09-13; Updated: 2026-09-15; Datestamp: 2026-09-15
We investigate the evolution of the high-energy excess in SWIFT J1727.8-1613 during its 2023 flare state using joint Insight-HXMT and INTEGRAL/ISGRI observations covering 2-500 keV. Fits to the broadband spectra with a model including thermal Comptonization and disk reflection leave systematic positive residuals above ~150 keV. Adding a power-law component improves the fits and yields photon indices of 2.08-2.61, demonstrating that the high-energy excess beyond the thermal Comptonization continuum is present throughout the flare state. We also show that all spectra can be well described by the hybrid Comptonization model eqpair, without requiring any additional high-energy component. The fitting results indicate that the energy supply to the electrons transitions from predominantly thermal heating to non-thermal acceleration, and that the electron injection spectrum steepens abruptly near the onset of the flare state. During this evolution, the radio spectral index changes from approximately zero to negative values, accompanied by the ejection of three transient JET knots. Based on this temporal association, we discuss a possible connection between the increase in non-thermal power indicated by our spectral analysis and the ejection of the transient JET.
[abstract 18 / 62] Yes (score: 4) - Title: Physics-Informed Neural Networks and Data-Driven Models for GRB X-ray Light-Curve Gap ReconstructionAuthors: Ayush Garg, Ritik Kumar, Maria G. Dainotti, Vipul Sharma, Amit Shukla, Dieter H. Hartmann,Comments: 36 pages, 6 figures, 7 tables, journal paperSubjects: astro-ph.HE astro-ph.COCreated: 2026-09-14; Updated: 2026-09-15; Datestamp: 2026-09-15
SWIFT-XRT X-ray afterglows of GAMMA-RAY BURSTs (GRBs) frequently contain temporal gaps that limit the precision with which the Willingale et al. 2007 (W07) plateau parameters measure plateau end time $T_a$, plateau flux $F_a$, and post-plateau decay index $α$. Because these parameters underpin the Dainotti relations (Dainotti et al. 2008, Dainotti et al. 2010, Dainotti et al. 2017), reducing their measurement uncertainty directly improves the cosmological statistical power of GRBs. As the fifth in a series of light-curve reconstruction studies (Dainotti et al. 2023, Manchanda et al. 2025, Kaushal et al. 2026, Gupta et al. 2026), this work benchmarks four models on 545 SWIFT-XRT GRBs: (i) a Physics-Informed Neural Network (PINN) under seven afterglow priors (Zhang et al. 2006, Nousek et al. 2006); (ii) ReFANN (Wang et al. 2020); (iii) a Siamese dual-branch network (Bromley et al. 1993, Gal et al. 2016); and (iv) Polynomial Quantile Regression (PQR; Koenker et al. 2005). All four methods reduce the fractional uncertainties in $\log T_a$, $\log F_a$, and $α$ relative to the original observations. The PINN broken power-law prior achieves the largest reductions ($\sim41$--$49\%$) at a higher outlier rate ($\sim15$--$20\%$), while ReFANN, the Siamese network, and PQR deliver consistent reductions ($\sim19$--$27\%$) with outlier fractions ($\lesssim4\%$) across a wider morphological range. A reduced-$χ^2$ prior-selection scheme recovers a morphological classification consistent with independent labelling, though without matching the best single-prior reduction. These results provide a systematic benchmark of physics-informed and data-driven reconstruction strategies for irregularly sampled GRB afterglows.
[abstract 19 / 62] Yes (score: 4) - Title: The effect of pressure confinement on the maximum mass of rapidly accreting supermassive starsAuthors: Lorenz Zwick, Christopher Tiede, Zoltán Haiman,Comments: Submitted to PRD, comments welcome!Subjects: astro-ph.HE astro-ph.GA gr-qcCreated: 2026-09-14; Updated: 2026-09-15; Datestamp: 2026-09-15
We derive an extension of Chandrasekhar's pulsational stability criterion for RELATIVISTIC stars with a pressure boundary condition at the surface. We then apply the new criterion to hylotropes, a model describing rapidly accreting supermassive stars with a core-envelope structure. We find that confinement typically stabilises stars, delaying the onset of the general RELATIVISTIC instability when the external pressure at the surface is roughly $\sim10^{-3}$ of the stars' hydrostatic pressure scale. Beyond this value, the critical mass at marginal stability increases rapidly, exceeding the value of $\sim 10^5$ M$_{\odot}$ for helium burning, isolated $n=3$ polytropes by orders of magnitude. We discuss how the required pressure boundary conditions may be produced by the combined ram and MAGNETic pressure supplied by the accretion flow as it assembles the supermassive star, and provide a fitting formula for the final mass before collapse. As a rough estimate assuming equipartition between MAGNETic and thermal pressures in a standard $α$-disk, we find that the critical mass doubles at accretion rates of order $\dot M\sim100\,{\rm M_\odot}\,{\rm yr}^{-1}$, again increasing rapidly after this value. Our results show under what conditions, potentially realized in a subset of high redshift halos, non-rotating SMS may collapse into BLACK HOLEs beyond the typical scale of heavy seeds.
[abstract 20 / 62] Yes (score: 4) - Title: Compelling evidence of a link between the lags of the quasi-periodic oscillations and the radio JET in the black-hole X-ray binary GRS 1915+105Authors: Candela Bellavita, Mariano Méndez, Federico García, Sara Motta, Pengcheng Yang, Wyncko Tonckens, Liang Zhang, Rob Fender,Comments: 12 pages, 7 figures; accepted for publication in Astronomy & AstrophysicsSubjects: astro-ph.HECreated: 2026-09-14; Updated: 2026-09-15; Datestamp: 2026-09-15
GRS 1915+105 is one of the most studied black-hole X-ray binaries, known for its extreme variability and rich phenomenology. Previous studies of this source with the Rossi X-ray Timing Explorer reported a transition of the phase-lags of type-C quasi-periodic oscillations (QPOs) from soft, where low-energy photons lag the high-energy ones, when the QPO frequency is higher than ${\sim} 2 ~{\rm Hz}$, to hard when the QPO frequency decreases below ${\sim} 2 ~{\rm Hz}$. The hard-lags of the QPO coincide with episodes of strong radio emission. We analyse NICER observations of GRS 1915+105 obtained between 2018 and 2020, during a period in which the source flux decreased steadily, and perform a detailed spectral-timing study of the detected type-C QPOs. We find a type-C QPO with frequencies in the range of ${\sim} 1.3$-$3.9 ~{\rm Hz}$, which displays soft lags and, contrary to the RXTE observations, shows no evidence of hard phase lags at frequencies below $2~{\rm Hz}$. Quasi-simultaneous AMI-LA radio observations show consistently low radio flux (${\lesssim} 5 ~{\rm mJy}$) during this period. These results appear to show that the hard QPO lags in GRS 1915+105 are linked to the presence of strong radio activity, suggesting that the RELATIVISTIC JET is responsible for the hard phase lags, supporting a scenario in which QPO phase lags trace changes in coronal geometry and accretion-ejection coupling in GRS 1915+105.
[abstract 21 / 62] Yes (score: 4) - Title: Impact of uncertainties on the cosmic optical and infrared backgrounds on the propagation of astroparticlesAuthors: Lucas Gréaux, Antonio Condorelli, Leonel Morejon, Karl-Heinz Kampert, Jonathan Biteau,Comments: Submitted to ApJSubjects: astro-ph.HE astro-ph.COCreated: 2026-09-14; Updated: 2026-09-15; Datestamp: 2026-09-15
When propagating through the universe, gamma rays at very-high energy (VHE, E > 100 GeV) and ultra-high energy COSMIC RAYs (UHECRs, E > 1 EeV) can interact with the optical, infrared and microwave photon fields that permeate the universe. These interactions result in a characteristic absorption imprint in the spectra of extragalactic gamma-ray sources at VHE, and in a change in the mass-composition of UHECRs. The study of both VHE gamma rays and UHECRs therefore requires precise knowledge of the intensity of the cosmic photon fields. In this work, we explore the impact of the current uncertainties on the optical and infrared photon fields on the propagation of astroparticles. We restrict the range of available models to those best matching the recent measurements, and compare the different reconstructions resulting from these models. We find that the knowledge on the cosmic background light is no longer the dominant source of uncertainties in understanding the phenomenology of astroparticle sources in the low redshift universe (z < 0.1), enabling robust spectral and composition inference with the next generation of both gamma-ray and UHECR measurements.
[abstract 22 / 62] Yes (score: 4) - Title: Common Excitation Patterns of Star Formation, Active Galactic Nuclei, and Shocks in Seyfert GalaxiesAuthors: Peixin Zhu, Lisa J. Kewley, Dominika Ł. Król, Giuseppina Fabbiano, Lars Hernquist, Ralph S. Sutherland, Anna Trindade Falcão, Martin Elvis, Riccardo Middei,Comments: 33 pages, 21 figures; published in ApJSubjects: astro-ph.GACreated: 2026-09-14; Updated: 2026-09-15; Datestamp: 2026-09-15
The growth of galaxies and their central supermassive BLACK HOLEs is closely connected, yet the net effect of ACTIVE GALACTIC NUCLEi (AGN) feedback on host-galaxy STAR FORMATION remains uncertain. AGN may enhance, suppress, or have little measurable impact on STAR FORMATION, but distinguishing among these outcomes requires separating star-formation and AGN photoionization from shock excitation, which is expected in AGN-driven outflows but has been difficult to isolate. Here we apply a recently developed theoretical three-dimensional diagnostic diagram, designed to separate STAR FORMATION, AGN, and shock excitation, to VLT/MUSE IFU observations of nine nearby (z < 0.026) Type 2 Seyfert galaxies. We find a common excitation pattern across the sample: star-forming rings or arcs at projected radii of r~0.8-6 kpc, AGN-photoionized bicones extending to kpc scales, central fast-shock-dominated regions that often extend perpendicular to the AGN bicone, and pure-shock- dominated regions surrounding the central fast shocks and appearing locally within the star-forming rings. Deep Chandra X-ray morphology independently supports this decomposition. The circumnuclear star-forming rings are consistent with bar-driven resonances, although positive AGN feedback may also contribute. The central fast shocks are broadly consistent with AGN JET-ISM interactions, while AGN wind-ISM interactions may also play an important role in galaxies with low-power JETs. These results establish central shocks as a common feature of Seyfert galaxies and demonstrate the importance of accounting for shock excitation in AGN feedback studies.
[abstract 23 / 62] (score: 3) - Title: Energy-Resolved Limits on Orbital X-ray Polarization Modulation in Cygnus X-1Authors: Sohee Chun, Bert Vander Meulen, Kun Hu, Henric Krawczynski,Comments: Accepted for publication in ApJ; revised upper-limit derivation, updated numbers throughoutSubjects: astro-ph.HECreated: 2026-09-11; Updated: 2026-09-15; Datestamp: 2026-09-15
Reflection off the companion star and its focused stellar wind is predicted to modulate the X-ray POLARIZATION of BLACK HOLE X-ray binaries at half the orbital period ($P_{\rm orb}/2$), with an energy-dependent amplitude. We test this prediction against all publicly available IXPE observations of Cygnus X-1, comprising 26 time bins of up to one day from 12 observation IDs spanning 2022-2024. Since the normalized Stokes parameters correlate linearly with the spectral hardness ratio in all three energy bands (2-4, 4-6, and 6-8 keV), we employ a simultaneous harmonic regression that decouples spectral variability from orbital modulation at both $P_{\rm orb}/2$ and $P_{\rm orb}$, complemented by direct fitting of 3D Monte Carlo radiative transfer stellar companion and wind-scattering templates. After removing the spectral hardness trend, neither approach reveals statistically significant orbital modulation: permutation tests yield $p > 0.01$ in all bands, with 99% confidence upper limits of 0.25%, 0.63%, and 1.96% on the $P_{\rm orb}$ amplitude and 0.42%, 0.97%, and 2.78% on the $P_{\rm orb}/2$ amplitude in the 2-4 keV, 4-6 keV, and 6-8 keV bands, respectively. The best-fit stellar companion and wind-scattering amplitude scaling factors in the three bands of $A = 0.67 \pm 0.85$, $0.97 \pm 0.62$, and $-1.06 \pm 1.11$ are consistent with a null result. These non-detections are sensitivity-limited, as the predicted stellar companion and wind-scattering RMS amplitudes in the three bands of $\approx$0.10%, $\approx$0.33%, and $\approx$0.49% lie below the statistical noise floor of $\sim$0.18%, $\sim$0.38%, and $\sim$1.01%. We quantify the additional exposure required to detect the predicted signal and constrain the wind physics.
[abstract 24 / 62] (score: 3) - Title: Multi-messenger View of White Dwarf Tidal Disruption Events by Intermediate-Mass Black Holes: I. Gravitational Waves and Disk Photon and Neutrino EmissionsAuthors: Jin-Hong Chen, Lixin Dai, Bing Zhang,Comments: 25 pages, 22 figures, Accepted for publication in ApJSubjects: astro-ph.HE astro-ph.GACreated: 2026-09-14; Updated: 2026-09-15; Datestamp: 2026-09-15
White dwarf (WD) tidal disruption events (TDEs) provide a unique window onto intermediate-mass BLACK HOLEs (IMBHs). We present a multi-messenger view of these systems in two papers. In this paper, we develop an accretion-disk model for WD--TDEs in which the bound debris accretes at extremely super-Eddington rates, $\sim 10^5$--$10^9$ times higher than in typical (main-sequence) TDEs. The model includes MAGNETic pressure, nuclear-burning heating, wind mass loss, and neutrino production via $e^{\pm}$ pair annihilation. At such high accretion rates, the gas and radiation temperatures of the inner flow can reach $T\gtrsim 10^9\,\mathrm{K}$, enabling prolific pair production and MeV neutrino emission. We find that the disk is predominantly advection dominated over a broad range of accretion rates, while disk winds can partially cool the flow and reduce the inner temperature. The predicted thermal EM emission is nearly insensitive to the fallback rate in the super-Eddington regime: the luminosity only mildly exceeds the IMBH Eddington luminosity and the spectrum peaks at $\sim 0.1$--$1\,\mathrm{keV}$, implying detectability with current X-ray facilities such as Einstein Probe. For low-mass IMBHs ($\sim 10^3\,M_{\odot}$), the disk can also produce a burst of MeV neutrinos with luminosities up to $\sim 10^{47}\,\mathrm{erg\,s^{-1}}$ for ONeMg WD--TDEs, although detectability with current neutrino detectors (e.g., Super-Kamiokande and JUNO) is limited to Galactic distances. Finally, we estimate the GW burst produced during the final passage prior to disruption, which peaks at $\sim 0.1$--$1\,\mathrm{Hz}$, placing WD--TDEs in the target band of proposed decihertz detectors and motivating coordinated GW+EM+neutrino searches. We also present a first exploration of GWs from a precessing WD--TDE disk; this signal is much weaker, with a detection horizon $\lesssim 1\,\mathrm{Mpc}$ for these missions.
[abstract 25 / 62] (score: 3) - Title: Early Near-Infrared Excess and Rapid Disk-Corona Evolution in the Tidal Disruption Event 2024aepdAuthors: Yongxin Wu, Yanan Wang, Thomas M. Reynolds, Shuyuan Wei, Shiyan Zhong, Zikun Lin, Megan Newsome, Sebastian Gomez, Iair Arcavi, Panos Charalampopoulos, Chun Chen, Rongfeng Shen, Ning-Chen Sun, David Aguado, Ismael Pérez-Fournon, Frédérick Poidevin, Zhongnan Dong, Niu Li, Weijian Guo, Hu Zou, Jingbo Sun, Nieves Castro-Rodríguez, Antonio Cabrera-Lavers, Ning Jiang, Hengxiao Guo, J. P. Anderson, Tomás E. Müller-Bravo, Seppo Mattila, Claudia P. Gutiérrez, Amit Kumar, G. Pignata, Xiangkun Liu, R. Dastidar, Brajesh Kumar, Xiaowei Liu, Bin Ma, M. Dennefeld, Francesca Onori, Lydia Makrygianni, Mariusz Gromadzki, Xuan Fang,Comments: Accepted for publication in Research in Astronomy and Astrophysics (RAA)Subjects: astro-ph.HECreated: 2026-09-14; Updated: 2026-09-15; Datestamp: 2026-09-15
We present multi-wavelength observations of the tidal disruption event (TDE) 2024aepd, spanning primarily the first $\sim$300 days after discovery. A prominent near-infrared (NIR) excess is detected as early as $\sim$40 days. Its nearly flat power-law spectrum strongly deviates from the Rayleigh-Jeans tail of the UV-optical blackbody. Although a conventional dust-echo origin cannot be completely ruled out, free-free emission from a reprocessing photospheric envelope provides a more plausible explanation. The spectral break between the UV-optical and NIR components shifts to higher frequencies, while the inferred density-profile index remains nearly constant, suggesting evolving reprocessing conditions within a broadly unchanged density structure. In addition, the X-ray spectrum is initially dominated by a thermal disk component accompanied by a hard excess. From $\sim$178 days onward, the spectrum becomes power-law dominated and subsequently hardens, indicating the rapid emergence and strengthening of a hot corona. These results provide evidence for frequency-dependent reprocessing at early times and for the rapid development of a disk-corona system, placing new constraints on the structure and evolution of the reprocessing layer around supermassive BLACK HOLEs.
[abstract 26 / 62] (score: 3) - Title: Examining Temporal Characteristics of GCRs in the AMS-02 eraAuthors: Cheng-Rui Zhu, Yu-Lu Liu, Mei-Juan Wang, Tian-Hao Li, Yi-Hua Zhu, Kai-Kai Duan,Comments: 16 pages, 9 figures, accepted by ApJSubjects: astro-ph.HECreated: 2026-09-12; Updated: 2026-09-15; Datestamp: 2026-09-15
The energy spectra of Galactic COSMIC RAYs (GCRs) serve as critical probes of their astrophysical origins and propagation mechanisms through the interstellar medium. Among the key physical processes shaping the observed spectra, solar modulation, driven by turbulent heliospheric MAGNETic fields and the variability of the solar wind, plays a dominant role in modifying GCR fluxes within the inner heliosphere. The recent release of time-dependent flux measurements for He, Li, Be, B, C, N, and O by AMS-02 provides unprecedented precision to investigate solar modulation phenomena. In this study, we demonstrate that Li, Be, B, C, N, and O nuclei exhibit solar modulation parameters consistent with those of protons (p) and He within a modified force-field approximation (FFA) framework incorporating rigidity-dependent modulation potentials. By positing that GCRs with the same charge-sign sharing the solar modulation parameters, we further forecast daily fluxes of Ne, Mg and Si from 2011 to 2020.
[abstract 27 / 62] (score: 3) - Title: Exploring the dynamics of the Coma galaxy cluster by mapping its X-ray emission line profiles with XRISMAuthors: Kosei Sakai, Kazuhiro Nakazawa, Maxim Markevitch, Dominique Eckert, Yuichiro Ezoe, Yuto Ichinohe, Richard Kelley, Richard Mushotzky, Nobuhiro Okabe, Yuki Omiya, Naomi Ota, Cicely Potter, Andrew Szymkowiak, Shunsuke Torii, Nhut Truong, Ayşegül Tümer, Yuusuke Uchida, Dan Wik, Irina Zhuravleva, John ZuHone,Comments: 9 pages, 5 figure, PASJ acceptedSubjects: astro-ph.HECreated: 2026-09-13; Updated: 2026-09-15; Datestamp: 2026-09-15
The intracluster medium (ICM) in merging galaxy clusters exhibits turbulence and bulk flows. Unraveling these components is crucial not only for elucidating the geometry of the cluster mergers, but also for understanding the physics of MAGNETic field amplification and RELATIVISTIC particle acceleration. XRISM/Resolve data for two $3'\times3'$ fields in the core of the Coma cluster reveales that the ICM in the central field moves with $Δcz = -430$~km~s$^{-1}$ relative to the cluster galaxy average, while that in the southern field moves with $Δcz = -730$~km~s$^{-1}$ (see \cite{2025ApJ...985L..20X}, hereinafter ``Paper I''). In this paper, we perform a more detailed analysis of these data sets to search for non-Gaussian features in the Fe-K line complex profiles. In the spectra from the northwest (NW) quadrant of the central field, in addition to the main and redshifted ICM components ($Δcz = -40$ km s$^{-1}$) reported in Paper I, we find evidence of another, blueshifted component, moving with $Δcz = -1250$ km s$^{-1}$. For a systematic search for other significant velocity components, we perform a bias-free 3 eV step multi-component fit to the Resolve full-array spectra from the central and southern fields. This search uncovers another redshifted component in the southern field, moving with $Δcz \sim +1230$ km s$^{-1}$. We estimate the energy densities of the ICM turbulence and bulk motion to be similar to each other and several times greater than the energy density of the cluster's $B\sim 5~μ$G MAGNETic field.
[abstract 28 / 62] (score: 3) - Title: Nitrogen-Loud Quasars from the Dark Energy Spectroscopic Instrument. II. Broad-Line Region Metallicity and Relative Nitrogen EnrichmentAuthors: Shuo Zhai, Wei-jian Guo, Yong-Jie Chen, Haining Li, Jian-Min Wang, Gang Zhao,Comments: Submitted to ApJSubjects: astro-ph.GACreated: 2026-09-13; Updated: 2026-09-15; Datestamp: 2026-09-15
Whether the unusually strong nitrogen emission in nitrogen-loud (N-loud) QUASARs reflects high overall metallicity, enhanced nitrogen abundance relative to other elements, or both has long been debated. We analyze the broad-line region (BLR) abundances of 121 N-loud QUASARs at $2.13 \leq z \leq 3.90$ selected from the Dark Energy Spectroscopic Instrument Data Release 1 and construct a control sample of normal QUASARs matched in redshift, continuum luminosity, and virial BLACK HOLE mass. Within the N-loud sample, metallicities inferred from N V/C IV span $\sim 3$-$50\,Z_\odot$ and are systematically higher than those inferred from the nitrogen-independent (Si IV+O IV])/C IV and Al III/C IV diagnostics, which agree closely and mainly span $\sim 1$-$20\,Z_\odot$. Compared with the matched controls, the N-loud QUASARs show systematically higher metallicities in both N V/C IV and (Si IV+O IV])/C IV, with median values approximately three times those of the controls. Notably, the discrepancy between the metallicities inferred from N V/C IV and (Si IV+O IV])/C IV becomes more pronounced toward the high-metallicity end of the N-loud sample, suggesting additional nitrogen enrichment beyond the overall metal enrichment. Together, these results indicate that N-loud QUASARs have both high overall BLR metallicity and enhanced relative nitrogen abundance, suggesting that relative nitrogen abundance is at least partially decoupled from overall metallicity. N-loud QUASARs therefore provide a high-metallicity laboratory for understanding how nuclear environments can produce unusual abundance patterns and offer a complementary view of how nitrogen enrichment arises across cosmic time.
[abstract 29 / 62] (score: 3) - Title: First results on the search for the Galactic Center Excess in the sub-GeV band with the emulsion telescope in GRAINE 2023Authors: Yuya Nakamura, Shigeki Aoki, Takashi Azuma, Hirotaka Hayashi, Yudai Isayama, Atsushi Iyono, Takumi Kato, Tsuyoshi Kawahara, Kohichi Kodama, Ryosuke Komatani, Masahiro Komatsu, Masahiro Komiyama, Hideyuki Minami, Kunihiro Morishima, Fumiya Murakami, Shogo Nagahara, Naotaka Naganawa, Mitsuhiro Nakamura, Tomoaki Nakamura, Noboru Nakano, Toshiyuki Nakano, Kazuma Nakazawa, Miyuki Oda, Kazuhiro Okamoto, Hiroki Rokujo, Osamu Sato, Kai Shimizu, Amon Suganami, Yuki Sugi, Kou Sugimura, Satoru Takahashi, Ikuya Usuda, Saya Yamamoto, Jun Yamashita, Mayu Yamashita, Shoma Yoneno, Masahiro Yoshimoto,Comments:Subjects: astro-ph.HECreated: 2026-09-13; Updated: 2026-09-15; Datestamp: 2026-09-15
Please check the paper for full abstract. The Galactic Center Excess (GCE) is an unexplained excess of gamma-ray emission from the Galactic Center. The GRAINE experiment aims to reveal the origin of the GCE using an emulsion gamma-ray telescope with high angular resolutions of 1 deg at 100 MeV and 0.1 deg at 1 GeV. In this study, we search for the GCE in a small region near the Galactic Center using the GRAINE 2023 flight data. In particular, rather than focusing on the spectral peak of the GCE at 2 GeV, we focused on the energy range below 300 MeV, where the spectral differences between the DARK MATTER annihilation and millisecond pulsar scenarios are more pronounced. We searched for the GCE within 1 deg of the Galactic Center in the 75--300 MeV energy range. Although no significant excess was observed, we obtained an upper limit on the GCE flux of 1.70*10^-7 GeV cm^-2 s^-1 at the 2 sigma confidence level for the 1deg-radius ROI centered on the Galactic Center, based on a direct observation of the narrow region around the Galactic Center. This observation requires high angular resolution and represents a unique result from GRAINE. The obtained upper limit is consistent with the GCE flux near the Galactic Center, which was estimated from existing FERMI-LAT observations using a wide ROI and assuming an NFW profile. Although the current upper limit constrains some models, the available statistics are still insufficient to distinguish between the DARK MATTER annihilation and millisecond pulsar scenarios, and both remain consistent with the current results. We also estimated the projected sensitivity of future GRAINE experiments based on the present observation and demonstrated their potential to probe the origin of the GCE by comparing the projected sensitivity with the predicted GCE spectra.
[abstract 30 / 62] (score: 3) - Title: Discovery of Two Consecutive Profile Change Events in the Millisecond Pulsar PSR J0437-4715Authors: Rami F. Mandow, Andrew Zic, J. R. Dawson, Shuangqiang Wang, Małgorzata Curyło, Bhavnesh Bhat, Michael J. Keith, N. D. Ramesh Bhat, Emma Carli, Shi Dai, Valentina Di Marco, Simon C. -C. Ho, Agastya Kapur, Wenhua Ling, Marcus E. Lower, Bradley W. Meyers, Saurav Mishra, D. J. Reardon, Sparrow Roch, Karolina Rozko, Christopher J. Russell, R. M. Shannon,Comments: 18 pages, 10 figures, submitted to MNRASSubjects: astro-ph.HECreated: 2026-09-14; Updated: 2026-09-15; Datestamp: 2026-09-15
The closest and brightest millisecond pulsar (MSP), PSR J0437-4715, is a high-priority pulsar for precision timing experiments, including the Parkes Pulsar Timing Array (PPTA) project, where it is used for both pulsar timing and for POLARIZATION calibration. Using approximately seven years of observations obtained with the Ultra-Wideband Low-Frequency receiver on Murriyang, CSIRO's Parkes radio telescope, we investigate the long-term spectro-polarimetric variability of PSR J0437-4715. We report the discovery of two consecutive discrete profile change events exhibiting the same phase-localised morphological variations, the first such behaviour reported in any MSP. Both events affect three phase-localised regions of the pulse profile that exhibit coupled and anti-correlated temporal evolution. We also identified, and corrected for, systematic profile variability induced by POLARIZATION calibration errors arising from long-term drift of the polarimetric properties of the receiver. The profile change exhibits frequency-dependent evolution in total intensity, together with variations in linear POLARIZATION, position angle and fractional linear POLARIZATION. These results confirm a MAGNETospheric origin for the events rather than propagation effects caused by the interstellar medium, and provide potential new constraints on MSP emission models.
[abstract 31 / 62] (score: 3) - Title: A DM candidate indicated at FERMI-LAT and LZ ? Connection with LHC and LC prospectsAuthors: Alain Le-Yaouanc, François Richard,Comments: 11 pages, 9 figures, to be presented at LCWS2026Subjects: hep-ph hep-exCreated: 2026-09-14; Updated: 2026-09-15; Datestamp: 2026-09-15
Recently an analysis of FERMI-LAT data has claimed a significant excess of energetic photons centred around 20 GeV, in the halo of our galaxy but absent in dwarf galaxies. This excess can be interpreted as coming from dark mater (DM) objects with a mass of few 100 GeV which annihilate into hadronic JETs containing photons mainly from neutral pions. This observation is independently backed up by a completely independent observation of the LUX-ZEPLIN (LZ) detector of a DM candidate in the same region of mass. To avoid contradiction with upper limits coming from dwarf galaxies, one is led to assume the presence of a spin 2 resonance coupled to these objects, which explains this difference as due to different speed distributions in the two regions. This work recalls that LHC data indicate a tower of Kaluza Klein graviton resonances. This solution is at variance with a SUSY interpretation of DM and therefore does not necessary call for a 1.1 TeV Higgsino, as often proposed. If these KK resonances are coupled to e+e-, as indicated by LHC data, an e+e- COLLIDER could observe these DM objects. LHC could confirm our KK graviton interpretation and, eventually, detect the DM particles. This would allow to define de energy needed at a future e+e- COLLIDER.
[abstract 32 / 62] (score: 3) - Title: Modeling Gamma-Ray Bursts Using CRISPAuthors: Leonel Morejon, Therese Paulsen, Karl-Heinz Kampert,Comments: 4 pages, 4 figures, to appear in the Proceedings of the 14th CRIS-MAC, 2026Subjects: astro-ph.HECreated: 2026-09-14; Updated: 2026-09-15; Datestamp: 2026-09-15
Astrophysical neutrinos are a clear identifier of photohadronic interactions in sources of Ultra-High-Energy Cosmic Rays (UHECRs). As the Pierre Auger Observatory has shown that UHECRs exhibit a composition heavier than protons at Earth, we expect that these heavy primaries undergo nuclear cascades due to photodisintegration in the dense source environments from which they originate. In this contribution, we will derive the neutrino spectra including those originating from nuclei undergoing photohadronic interactions. This will be explored in the context of modeling the emission region of a GAMMA-RAY BURST. Photohadronic interactions will be modeled using the new framework for Cosmic Ray Stochastic Interactions for Propagation (CRISP), which employs an analytic approach to compute the underlying probabilistic description of UHECR interactions.
[abstract 33 / 62] (score: 2) - Title: Pinched Multi Affine Geometry and Confinement: Describing the Yang-Mills Mass GapAuthors: Shoshauna Gauvin,Comments:Subjects: physics.gen-phCreated: 2026-09-14; Updated: 2026-09-15; Datestamp: 2026-09-15
We give physical gap certificates for regulated Yang-Mills Hamiltonians and conditional continuum-transfer criteria. At fixed spatial cutoff, the physical $SU(3)$ Hamiltonian has a volume-independent gap of at least $8a/3$ for MAGNETic/electric ratio $b/a\le1/648$, with a thermodynamic ground state and a surviving finite-energy Wilson excitation. Its centered two-point autocorrelations have positive spectral representations; on the stated periodic cubes, every positive MAGNETic coupling gives the elementary plaquette at least two active energies. Quantum relative entropy identifies the physical energy form, while exact elimination retains the dynamical memory of discarded modes. We derive volume- and exterior-uniform vacuum score bounds, construct compatible finite hierarchies, and give summability and spectral-tightness criteria for limiting dynamics and surviving observables. Pinching motivates a conditional tube-energy balance; its use for an infrared gap requires uniform comparison with the complete vacuum-subtracted quantum energy after relaxation, including control of local low modes and localization errors. The remaining inputs include uniform infrared and shell estimates, local vacuum comparison rates, and RELATIVISTIC field reconstruction. The interacting four-dimensional construction, nontrivial renormalized local fields and a uniform physical mass gap remain unproved.
[abstract 34 / 62] (score: 2) - Title: Survival of ultraheavy nuclei in astrophysical sources: applications to protoMAGNETar outflowsAuthors: Nick Ekanger, Mukul Bhattacharya, Kohta Murase, Shunsaku Horiuchi,Comments: 14 pages, 5 figures, 1 table. This matches the version published in PRDSubjects: astro-ph.HE hep-ph nucl-thCreated: 2026-09-14; Updated: 2026-09-15; Datestamp: 2026-09-15
Outflows of rapidly rotating protoMAGNETars have been considered as attractive sites for the synthesis of nuclei heavier than iron, but the question remains whether these nuclei are able to survive against photodisintegration as they make their way out of their formation environments. In this work, we present new analytic fitting formulae for the photodisintegration cross sections applicable to heavy nuclei beyond iron. We confirm that the results from the TALYS simulations are consistent with the theory of the giant dipole resonance, and apply the obtained new formulae to investigate whether ultraheavy nuclei entrained in protoMAGNETar outflows can be disintegrated by thermal and nonthermal photons before leaving the stellar envelope. We explore two outflow models: a spherical wind model and a JETted outflow model. For nuclei accelerated to the bulk speed of these outflows, their survival depends on the model and engine properties. For spherical winds, nuclei may survive for the first $\sim100\,{\rm s}$ post-core collapse, but as the wind Lorentz factor increases, the photodisintegration optical depth sharply rises and nuclei may no longer survive. For the JETted outflows arising from progenitors surrounded with stellar envelopes, nuclei can only survive before the JET breakout time in cases where the central engine has high spin-down energy, that is, with a high MAGNETic field strength and shorter spin period. In progenitors with more extended envelopes, the JET break out time is much longer, allowing for nonthermal photons to readily photodisintegrate nuclei in high spin-down energy cases. These results also outline some of the necessary, but not yet sufficient, conditions to source ultrahigh-energy cosmic-ray nuclei.
[abstract 35 / 62] (score: 2) - Title: Searching for Black Hole Candidates in Quiescence by Using Multi-band Observations in Globular Cluster M22 (NGC 6656)Authors: Yu-Jing Xu, Wei-Min Gu, Yuanqi Liu, Xin-Yu Fang, Shan-Shan Weng, Tao An,Comments: 14 pages, 6 figures, 4 table, accepted for publication in ApJSubjects: astro-ph.HECreated: 2026-09-14; Updated: 2026-09-15; Datestamp: 2026-09-15
We present a multi-wavelength investigation of radio sources in the globular cluster M22 (NGC 6656) using the Karl G. Jansky Very Large Array, Chandra and Hubble Space Telescope. By cross-matching the radio and X-ray source catalogs, we identify eight radio/X-ray counterparts, of which VLA22 is the most promising stellar-mass BLACK HOLE (BH) candidate. Its radio and X-ray luminosities are consistent with the established $L_{\rm X}-L_{\rm R}$ correlation for BH low-mass X-ray binaries. The observed X-ray variability supports an accreting nature. One possible optical counterpart ($M_{\mathrm{814}} \approx 16.695 \pm 0.011$ mag) is identified. Based on its inferred stellar parameters, the estimated orbital period of $P_{\rm orb} \sim 16 \pm 6~{\rm h}$ places the proposed counterpart predominantly in the BH region rather than in the NS region in the $L_{\rm X}-P_{\rm orb}$ plane. These results demonstrate the effectiveness of joint radio, X-ray, and optical observations in identifying quiescent BH candidates in globular clusters.
[abstract 36 / 62] (score: 2) - Title: Statistical Flux Freezing with Magnetic Path-lines in TurbulenceAuthors: Amir Jafari,Comments:Subjects: physics.plasm-phCreated: 2026-09-11; Updated: 2026-09-15; Datestamp: 2026-09-15
Magnetic flux freezing states that, in ideal MAGNETohydrodynamics, MAGNETic flux is transported by the flow and MAGNETic field lines remain frozen into the plasma. In turbulent plasmas, however, the velocity and MAGNETic fields are spatially rough, invalidating the regularity assumptions underlying the classical theorem. Previous work has shown that Lagrangian trajectories in such rough flows can become nonunique in the limit of small MAGNETic diffusivity, leading to stochastic formulations of MAGNETic flux freezing based on MAGNETic field lines. Field lines, however, are instantaneous geometric objects that do not possess a natural time evolution and do not preserve identity in turbulent flows. We instead use MAGNETic path lines, which remain intrinsically stochastic in the ideal limit, implying that MAGNETic flux is conserved only in a statistical sense over ensembles of backward-advected path-line surfaces. This yields a statistical formulation of Alfven's theorem in terms of MAGNETic path lines and shows that the classical deterministic form of flux freezing cannot hold in sufficiently rough turbulent MAGNETic fields. While closely related in physical content to earlier stochastic flux-freezing approaches based on MAGNETic field lines, the path-line formulation provides time-evolving dynamical trajectories that retain identity in spacetime and offer a simpler and more transparent framework for analyzing stochastic MAGNETic transport.
[abstract 37 / 62] (score: 2) - Title: Pfirsch-Schlüter CurrentAuthors: Allen H Boozer,Comments:Subjects: physics.plasm-phCreated: 2026-09-13; Updated: 2026-09-15; Datestamp: 2026-09-15
The Pfirsch-Schlüter current is a current that flows along the MAGNETic field lines in a toroidal plasma equilibrium that is required to make the plasma current density divergence free in the presence of a plasma-pressure gradient. A distortion in the plasma shape is caused by the Pfirsch-Schlüter current, and it is desirable to minimize both the strength and the distance this current flows along the MAGNETic field lines. The Pfirsch-Schlüter current is localized within a half period of a stellarator when $d\ell/B$ integrated over the half period is the same for all lines in the MAGNETic surface. It is shown that within parts in a thousand this is the same condition as the distance $\ell_{s}$ required for a field line to cross the half period being the same for all lines in the surface. To make the $\ell_{s}$'s the same, the lines started on the small major radius side of the plasma must undergo wiggles to make their $\ell_{s}$ as long as those started on the outboard side. This is generally achieved using modular coils with a large helical component on the small major radius side but could be achieved with a central column carrying a helical current.
[abstract 38 / 62] (score: 2) - Title: The nature of `little blue dots'Authors: Albert Sneppen, Darach Watson, James H. Matthews, Georgios Nikopoulos,Comments: Accepted to A&ASubjects: astro-ph.GA astro-ph.HECreated: 2026-09-12; Updated: 2026-09-15; Datestamp: 2026-09-15
Previous Sirocco radiative-transfer models of gas-cocooned AGN predicted lower-column counterparts to little red dots (LRDs): compact, X-ray-weak sources with bluer continuum slopes and Balmer jumps rather than Balmer breaks. The recently identified population of little blue dots (LBDs) closely resembles this predicted phase. Here we explore these lower-column-density cocoons in which nebular recombination emission remains visible while strong Balmer-continuum absorption is avoided. We find that a sequence of increasing column density connects more classical AGN spectra, Balmer-jump LBD-like spectra at $N_{\rm H}\!\sim\!{\rm few}\times10^{24}\,\mathrm{cm^{-2}}$, and Balmer-break LRD-like spectra at higher columns. Along this sequence, electron scattering produces exponential line wings and suppresses X-ray emission before strong Balmer absorption features emerge. The models predict that LBDs should share X-ray weakness and exponential line wings with LRDs, while being distinguished by Balmer jumps in emission, weak or absent absorption features, potential He II $λ$4686 emission, lower H$α$ luminosities and narrower H$α$ lines. We compare with spectra of eight LBDs and find that significant Balmer-jump signatures are common. We therefore suggest that LBDs are lower-column analogues of LRDs within a common gas-cocooned AGN sequence.
[abstract 39 / 62] (score: 2) - Title: Robust Control of ECH Deposition Profiles on DIII-DAuthors: H. J. Farre-Kaga, A. Rothstein, K. Yasoda, J. Lestz, N. Chen, S. K. Kim, A. Jalalvand, E. Kolemen,Comments: 20 pages, 9 figuresSubjects: physics.plasm-phCreated: 2026-09-11; Updated: 2026-09-15; Datestamp: 2026-09-15
Electron Cyclotron Heating (ECH) is a key actuator in DIII-D and future tokamaks that provides auxiliary heating, localized current drive for scenario development and MHD stability, and even impurity pump-out. Due to its control flexibility and applications, a gyrotron optimization algorithm was developed to multitask and fine-tune the deposition location and heating power of each gyrotron while providing robustness to hardware failure. The ECH Optimization (ECHO) algorithm finds the optimal gyrotron mirror angle and power to achieve a target ECH radial deposition profile. This optimization is accomplished in real-time using a parallelized neural network surrogate of the TORBEAM code combined with a genetic optimizer. This has been deployed in a DIII-D experiment and has been validated with experimental ECE measurements and post-experiment offline ray tracing, showing the algorithm's reliability despite gyrotron failures and significant changes to plasma parameters.
[abstract 40 / 62] (score: 2) - Title: When the BLACK HOLEs align: a subpopulation of aligned massive binary BLACK HOLEs observed via gravitational wavesAuthors: Stefano Rinaldi, Charmaine Wong, M. Paola Vaccaro, Elvir Mislimi, Otto A. Hannuksela, Samson H. W. Leong, Michela Mapelli,Comments: 9 pages, 6 figures. Matched version accepted for publication in Astronomy & AstrophysicsSubjects: astro-ph.HECreated: 2026-09-14; Updated: 2026-09-15; Datestamp: 2026-09-15
In this work, we investigate the features present in the joint primary mass and effective spin distribution of binary BLACK HOLEs without relying on specific modelling assumptions. We make use of non-parametric methods, flexible models capable of approximating arbitrary probability densities with minimal mathematical assumptions, applying it to the newly released GWTC-5.0. Our analysis supports, albeit with large uncertainties, the presence of at least two separate sub-population of binary BLACK HOLEs showing different effective spin distributions: one of them, preferring positive $χ_\mathrm{eff}$ values, points towards the direction of systems formed in a non-spherically-symmetric, dynamical environment.
[abstract 41 / 62] (score: 2) - Title: Probing Nonlinear Logarithmic Kalb-Ramond Black Holes: Particle Dynamics, Epicyclic Oscillations and Thermodynamic SignaturesAuthors: Aftab Ansari, Rajesh Kumar, Praveen Kumar Dhankar,Comments:Subjects: gr-qc astro-ph.HECreated: 2026-09-13; Updated: 2026-09-15; Datestamp: 2026-09-15
In contrast to conventional linear coupling frameworks, the proposed work investigated the nonlinear effects that become more significant in the strong field regime of a BLACK HOLE. We have investigated a new class of Kalb Ramond BLACK HOLEs generated by a nonlinear logarithmic coupling of the field, referred to as a Logarithmic Kalb Ramond BLACK HOLE. The logarithmic coupling introduces strong-field modifications to the spacetime geometry, leading to significant departures from the Schwarzschild and Reissner Nordstrom BHs. We analyze the motion of test particles using the effective potential formalism and derive the conserved energy and angular momentum for circular equatorial geodesics. The stability of circular orbits and the location of the innermost stable circular orbit are examined, revealing a strong dependence on the model parameters Q, l, and $β$. The epicyclic frequencies (radial, vertical, and azimuthal) together with the associated periastron precession demonstrate that nonlinear logarithmic corrections can substantially modify quasi periodic oscillation observables. We further investigate the Hawking temperature and energy emission rate, which show that the nonlinear coupling also impacts distinct imprints on the thermodynamic behavior and evaporation characteristics of the BLACK HOLE. Our results also identify the BH parameters as key regulators of the orbital dynamics, oscillatory properties, and thermal evolution, providing a unified framework for probing nonlinear KR gravity through strong-field astrophysical phenomena.
[abstract 42 / 62] (score: 2) - Title: Optical Images of the Braneworld Black Hole Surrounded by an Optically Thin Accretion DiskAuthors: Wen-Hao Deng, Sen Guo, Qing-Quan Jiang, Kai Lin, Pei Wang,Comments:Subjects: astro-ph.HECreated: 2026-09-13; Updated: 2026-09-15; Datestamp: 2026-09-15
This work examines the observational signatures of rotating BLACK HOLEs with tidal charge in the Randall--Sundrum braneworld scenario. Combining an elliptic-integral-based analytical treatment with numerical ray tracing, we characterize photon motion around braneworld BLACK HOLEs in detail. For small observer inclinations, secondary images remain embedded inside the primary emission rings. As the inclination becomes larger, the primary and secondary images gradually separate and produce a strongly asymmetric image morphology. We show that the image asymmetry and the deformation of the inner shadow are jointly controlled by the BLACK HOLE spin, the tidal charge, and the observer inclination. To analyze the frequency shifts across the accretion disk, we extend the emitting region from the ISCO down to the event horizon by including the plunging flow. The results indicate that the observer inclination is the dominant factor governing the frequency-shift distribution. In addition, we reconstruct braneworld BLACK HOLE images using a fisheye-lens ray-tracing model. The optical morphology and brightness distribution show a clear dependence on the observing frequency, especially when comparing 230~GHz with 86~GHz. We also contrast the brightness distributions of prograde and retrograde disks, finding that both the total intensity and the peak intensity at 86~GHz are higher than those at 230~GHz. For negative values of the tidal charge, we further investigate the corresponding frequency-shift behavior and 230~GHz intensity profiles, which may provide useful theoretical guidance for future studies of extra-dimensional gravity models.
[abstract 43 / 62] (score: 2) - Title: HST imaging, pipeline modeling, and time-delay predictions of 2 triply-imaged and 15 quadruply-imaged lensed QUASARsAuthors: William Sheu, Tommaso Treu, Adriano Agnello, Timo Anguita, Simon Birrer, Daniel Gilman, Xiaosheng Huang, Richard G. McMahon, Nicholas D. Morgan, Veronica Motta, Anna Nierenberg, Kenneth C. Wong, Ioana Zelko,Comments: 18 pages, 6 figures, submitted to Physical Review DSubjects: astro-ph.CO astro-ph.GACreated: 2026-09-13; Updated: 2026-09-15; Datestamp: 2026-09-15
The Hubble tension remains a significant challenge in modern cosmology, exhibiting a discrepancy between early-Universe cosmic microwave background measurements and local distance ladder observations. Strong lensing time-delay cosmography provides an independent, geometric probe of $H_0$ that can help resolve this discrepancy. Although hundreds of lensed QUASARs have been discovered, only a handful have been analyzed due to the resource-intensive follow-up required to measure precise time delays and break degeneracies. We present uniform gravitational lens modeling of 17 recently discovered lensed QUASAR systems (2 triply-imaged and 15 quadruply-imaged) to identify and prioritize the most promising candidates for future cosmological study. Using high-resolution near-infrared Hubble Space Telescope WFC3/IR F160W imaging (PID: 17916, PI: T. Treu), we perform uniform pipeline modeling with Lenstronomy. We constrain the mass and light profiles of the deflector galaxies, and assuming a fiducial cosmology, we predict their Fermat potential differences and expected time delays. Our pipeline successfully yields models and time-delay predictions for all 17 systems. Assuming ideal monitoring conditions, we estimate the total contribution from time-delay and Fermat potential modeling errors to the time-delay distance. From this, we classify the systems by estimated time-delay distance uncertainties: six "excellent" ($\leq 3\%$), five "good" ($3\%$-$7\%$), three "suitable" ($7\%$-$12\%$), and three "impractical" ($>12\%$). We recommend prioritizing follow-up campaigns on the 11 "excellent" and "good" systems, which have the potential to deliver high-precision, independent constraints on $H_0$ to help resolve the Hubble tension.
[abstract 44 / 62] (score: 2) - Title: Portraits of the young and old in X-ray: New millisecond pulsar detections and updated characterization of young neutron starsAuthors: Wynn C. G. Ho, Patrick H. Wang, Sebastien Guillot,Comments: 7 pages, 7 figures; published in MNRAS; corrected typo in position error quoted from other paperSubjects: astro-ph.HE astro-ph.SRCreated: 2026-09-14; Updated: 2026-09-15; Datestamp: 2026-09-15
We present analyses of new and archival Chandra and NUSTAR data on two old millisecond pulsars, a young highly-energetic pulsar, and a young neutron star. PSR J1810-0623 is a recently-discovered 4.55 ms radio pulsar in a binary with a possible carbon-oxygen white dwarf companion. We tentatively detect the pulsar for the first time in X-ray using a new short Chandra HRC-I observation. Its faintness suggests a distance more in accord with the further (~1 kpc) of its dispersion measure-inferred distances. PSR J1933-6211 is a 3.54 ms radio pulsar also with a carbon-oxygen white dwarf companion. Our first-time X-ray detection in an archival HRC-S image indicates its X-ray luminosity is similar to that of the 1.9 Msun pulsar PSR J1614-2230. Next, PSR J1813-1749 is a 1-2 kyr pulsar with one of the highest known spin-down luminosities. We measure its spin period of 44.7 ms using 2025 NUSTAR and 2026 Chandra ACIS-S data and update its spin evolution model. We show for the first time the pulse profile of PSR J1813-1749 at 3-79 keV, and we find that the spectra of the pulsar and pulsar wind nebula at these energies did not change significantly between observations in 2018 and 2025. Finally, for the 5-10 kyr neutron star CXOU J182913.1-125113 in the SUPERNOVA remnant G18.95-1.1, we combine ACIS-I observations from 2009 and 2024 to better measure the neutron star's spectrum.
[abstract 45 / 62] (score: 2) - Title: GRINTA: a new Probe of the Dynamic UniverseAuthors: Lorenzo Natalucci, Philippe Laurent, Marica Branchesi, Mariateresa Fiocchi, Lorraine Hanlon, J. Miguel Mas-Hesse, Aline Meuris, Paul 'O Brien, James C. Rodi, Simone Scaringi, Konrad Skup, Norbert Werner, Silvia Zane, Julia Alfonso-Garzon, Biswajit Banerjee, Patrizia Barria, Anthony J. Bird, Soren Brandt, Gabriele Bruni, Floriane Cangemi, Gianluca Castignani, Eric Chassande-Mottin, Sylvain Chaty, Jerome Chenevez, Alexis Coleiro, Francesco Dazzi, Alessio L. De Santis, Phil Evans, Olivier Godet, Diego Gotz, Rene Hudec, Lucien Kuiper, Angela Malizia, Sheila McBreen, Sandro Mereghetti, Manuela Molina, Filip Munz, David Murphy, Gor Oganesyan, Francesca Panessa, Elena Pian, Jakub Rıpa, Oliver J. Roberts, Samuele Ronchini, Fabian Schussler, Vojtech Simon, Nial Tanvir, Alexey Uliyanov, Nello Vertolli, Stanislav Vıtek, Ugo Zannoni,Comments: Presented at SPIE Astronomical Telescopes and Instrumentation 2026. 24 pages, 8 figures, 3 tablesSubjects: astro-ph.IM astro-ph.HECreated: 2026-09-14; Updated: 2026-09-15; Datestamp: 2026-09-15
Recent observations of the transient sky at all wavelengths are increasingly revealing the importance of the multi-messenger and multi-wavelength approach. The GRINTA (Gamma-Ray INternational Transient Array Observatory) mission, proposed for launch around the middle of the next decade, is conceived as a small mission with good sensitivity, excellent angular resolution and fast follow-up capability for studying transient sources at timescales from ms to hours, at the same time ensuring optimal integration with multi-messenger networks. The GRINTA mission will carry two complementary payloads to cover in total the 5 keV-10 MeV band, that will detect and localise GAMMA-RAY BURSTs covering $\sim$ half of the sky and will be able to perform imaging surveys with sub-arcmin resolution. GRINTA will operate in synergy with the most powerful electroMAGNETic, gravitational wave and neutrino observatories foreseen to be operational after 2035.
[abstract 46 / 62] (score: 2) - Title: Dispersion Measure Variability in Fast Radio Bursts from PhotoionizationAuthors: Brian D. Metzger,Comments: submitted to ApJSubjects: astro-ph.HECreated: 2026-09-14; Updated: 2026-09-15; Datestamp: 2026-09-15
Magnetars became favored engines of fast radio bursts (FRBs) following the discovery of a luminous radio burst coincident with a hard X-ray flare from a Galactic MAGNETar. Several repeating FRB sources exhibit time-variable rotation measures and compact, spatially coincident persistent radio emission, consistent with energetic-particle nebulae confined by young SUPERNOVA ejecta. Secular changes in the dispersion measure (DM) of repeating FRBs have also been observed, offering a complementary probe of their local environments; for example, the DM of FRB 121102 rose until 2019 before declining in recent years. Although rising DM evolution has been attributed to shock ionization, shocked ejecta can cool efficiently through metal-line emission and recombine, especially if mixed with cooler gas. Here we argue that DM variations of the observed magnitude and timescale instead arise from changes in the ionization state of SUPERNOVA ejecta irradiated by X-rays from a time-variable central engine. The dominant rapidly variable contribution comes from the dense, weakly ionized shell swept up by the expanding nebula, whose ionization and recombination times are shorter than those of the more extended ejecta. The model predicts that enhanced FRB activity should be accompanied by rising DM, with a response smoothed over the ionization/recombination time and superposed on a slower secular decline from ejecta expansion. In FRB 121102, the DM maximum occurred close to the burst-rich 2018-2019 activity episodes. If the recently reported renewed activity is sustained, its DM decline should flatten and may reverse into a fresh rise over the coming years.
[abstract 47 / 62] (score: 2) - Title: Connecting Dynamo Theory with DNS Data: A Computational Analysis of $α$ and $β$ EffectsAuthors: Kiwan Park,Comments: 26p, IDL analysis code in AppendixSubjects: astro-ph.SR physics.plasm-phCreated: 2026-09-14; Updated: 2026-09-15; Datestamp: 2026-09-15
We investigate the influence of current helicity on the turbulent MAGNETic diffusivity $β$ using three complementary derivations of the $α$ and $β$ coefficients, based on the large-scale MAGNETic field $\overline{\mathbf{B}}$, the turbulent velocity $\mathbf{u}$, and the turbulent MAGNETic field $\mathbf{b}$. Applying these coefficients to raw DNS data, we reconstruct $\overline{\mathbf{B}}$ and compare the results with the original simulations. In the kinematic regime all models agree well with the DNS data. In the nonlinear regime, however, $β_{\mathrm{vv-vw}}$ alone produces unbounded growth of $\overline{\mathbf{B}}$. Including the contribution from turbulent MAGNETic fields ($β_{\mathrm{bb+jb}}$) suppresses this unphysical growth and restores agreement with the DNS results. We find that kinetic helicity drives $β$ more negative, while current helicity shifts it back toward zero. Weighted combinations of the coefficients further show that the $β$ effect dominates the evolution of $\overline{\mathbf{B}}$ throughout, whereas the $α$ effect becomes important mainly for sustaining the field in the nonlinear regime. The corresponding IDL analysis scripts are provided to facilitate practical implementation of the theoretical models.
[abstract 48 / 62] (score: 2) - Title: Gas absorption of soft X-rays strongly impacts the redshift distribution of dark Fast X-ray TransientsAuthors: Javier Sánchez-Sierras, Peter G. Jonker, Jonathan Quirola-Vásquez, Agnes P. C. van Hoof, Andrew J. Levan, Maria E. Ravasio, Joyce N. D. van Dalen, Franz E. Bauer, Jia-Ying Cao, Francesco Carotenuto, Jennifer A. Chacón, Ashley A. Chrimes, Laura Cotter, Gregory Corcoran, Rob A. J. Eyles-Ferris, Guoli Huang, Shuai-Qing Jiang, Zexi Li, Yifang Liang, He-Yang Liu, Daniele B. Malesani, Antonio Martin-Carrillo, Daniel Mata Sánchez, Nikhil Sarin, Manuel A. P. Torres, Qinyu Wu, Tong Zhao, Wen-Da Zhang,Comments: Accepted for publication in MNRASSubjects: astro-ph.HECreated: 2026-09-11; Updated: 2026-09-15; Datestamp: 2026-09-15
The progenitors of many Fast X-ray Transients (FXTs) and those of $γ$-ray bursts (GRBs) are strongly linked. Given that "dark" GRBs are typically found to be events suffering from enhanced extinction in the host galaxy, we investigate the nature of "dark" FXTs. However, unlike $γ$-rays, soft X-rays are strongly affected by absorption, implying that dark FXTs discovered by Einstein Probe's Wide-field X-ray Telescope (EP-WXT) have to be emitted at energies $>$2--3 keV restframe hence at a redshift $z\gtrsim2$. To illustrate this we present two dark FXTs, EP241103a and EP260409a, discovered by EP-WXT. For EP241103a, the high extinction precluded the detection of the optical counterpart, while for a probable source redshift of $\sim2.5$, the rest-frame X-ray photons are not severely affected. For EP260409a no counterpart is detected in the optical, but we do detect a near-infrared counterpart. A plausible scenario for EP260409a is that it lies at a redshift $z \gtrsim 4$. Additionally, we conduct simulations of FXTs observed with EP-WXT, showing that the detected counts for absorbed events ($N_{\mathrm{H}}\gtrsim10^{22}$~cm$^{-2}$) strongly decrease at low redshifts, hindering their detection. These results support the theoretical prediction that dark FXTs have an intermediate to high redshift and a different selection function from those of dark GRBs.
[abstract 49 / 62] (score: 2) - Title: Black Hole Solutions with Scalar Fields and Anisotropic Matter in Non-Minimal $Y(R)F^2$ GravityAuthors: Özcan Sert,Comments: 39 pagesSubjects: gr-qcCreated: 2026-09-12; Updated: 2026-09-15; Datestamp: 2026-09-15
We investigate exact spherically symmetric and static BLACK HOLE solutions in a non-minimally coupled Einstein--Maxwell theory of the $Y(R)F^2$ type, extended by a minimally coupled real scalar field and an anisotropic matter distribution. The Maxwell field is coupled to the spacetime curvature through an arbitrary function of the Ricci scalar, while the scalar field is described by a kinetic term and a scalar potential. We obtain exact solutions for power-law and logarithmic forms of the non-minimal coupling function and analyze the corresponding spacetime geometries. In particular, we identify a special $β=-1/3$ case for which the general power-law solution becomes singular and derive a new logarithmic metric by solving the field equations independently. The resulting configurations are asymptotically flat and exhibit modified gravitational properties associated with the interplay between the scalar field, anisotropic matter, and non-minimal electroMAGNETic coupling. We further show that the MAGNETic solutions admit electrically charged counterparts through an electroMAGNETic duality transformation, under which the metric and scalar sector remain invariant while the non-minimal coupling function is inverted. The obtained solutions provide a useful framework for investigating BLACK HOLE horizons, thermodynamic properties, geodesic motion, and astrophysical phenomena such as galactic rotation curves in curvature-dependent electroMAGNETic theories.
[abstract 50 / 62] (score: 2) - Title: The Galactic Black Hole mass distributionAuthors: L S. Rocha, N. Pires, L. M. de Sá, B. B. Martins, L. G. Barão, G. R. C. Sampaio, D. V. Rodrigues, R. M. G. Takahashi, M. G. B. de Avellar, J. E. Horvath, A. Bernardo,Comments: 31 pages, 17 figuresSubjects: astro-ph.HECreated: 2026-09-12; Updated: 2026-09-15; Datestamp: 2026-09-15
The population of extragalactic BLACK HOLEs has been significantly expanded and better understood since the first detection of gravitational waves. Over the past decade, approximately 290 events have been confirmed to involve at least one BLACK HOLE. In contrast, the galactic BLACK HOLE population has grown at a much slower pace, with only 42 systems possessing mass estimates, while the vast majority remain as candidates. In this work, we present the first update of a Bayesian analysis of the mass distribution of galactic BLACK HOLEs since 2011, previously based on a sample of 15 low-mass X-ray binaries and 5 high-mass X-ray binaries. Our update includes 28 low-mass X-ray binaries, 6 high-mass X-ray binaries, 7 detached binaries and 1 isolated BLACK HOLE, also present in the living catalog \textit{CatNoir} which we introduce. We apply a Bayesian framework using five parametric models -- Gaussian, two-Gaussian, log-normal, power-law, and decaying exponential -- and compare their performance in fitting the observed data. Furthermore, we inspect the effect of removing model-dependent systems from the sample. Our results suggest that the power law better describes the Combined sample, while the Gaussian is preferred for the LMXB-only sample, closely followed by the two-Gaussian and log-normal. We derive the $1\%$-quantile of the preferred model's posterior predictive distribution to access information about the lower mass gap. For the Combined and LMXB Samples, we find $M_{1\%} > 4.06\,M_\odot$ and $M_{1\%} > 2.56\,M_\odot$ (at $90\%$ C.I.), respectively. The LMXB result allows for the existence of a sparsely populated Gap, instead of a completely empty one.
[abstract 51 / 62] (score: 2) - Title: Embracing Flow Unsteadiness: A High-Throughput Learning Platform Enables Vortex-Exploiting Bioinspired PropulsionAuthors: Fei Han, Xinyu Cui, Zhipeng Wang, Ning Yang, Hang Xu, Haifeng Zhang, Zhongming Hu, Jun Wang, Junfeng Du, Dixia Fan,Comments:Subjects: physics.flu-dyn cs.ROCreated: 2026-09-13; Updated: 2026-09-15; Datestamp: 2026-09-15
Biological swimmers and flyers exploit unsteady vortices for propulsion, whereas engineered vehicles usually suppress them as disturbances. Learning such flow exploitation in machines is difficult because real-fluid interaction data are scarce and unstructured exploration is unstable in high-dimensional, history-dependent flows. Here we present REEF, a co-designed physical-learning framework that integrates SHOAL, an eight-channel high-throughput array for real fluid--structure interaction, with V-STAR, a staged algorithm that converts these interactions into policies through imitation, offline internalization, and online adaptation. Across lift-based, drag-based, and momentum-JET propulsors, REEF expands the attainable force envelope to more than twice that of parameterized search. Particle image velocimetry shows that these gains arise from coordinated vortex formation, growth, and force projection, rather than refinement of a fixed motion-to-force mapping. Force-trained policies transfer zero-shot to free-moving robots whose body motion changes the surrounding flow, suggesting that REEF learns transferable wake-coupling principles for embodied propulsion in unsteady fluids.
[abstract 52 / 62] (score: 2) - Title: Perturbations and quasinormal modes of BLACK HOLEs in general relativity coupled to nonlinear electrodynamicsAuthors: Uktamjon Uktamov, Bakhtiyor Narzilloev, Ibrar Hussain, Bobomurat Ahmedov, Chengxun Yuan,Comments:Subjects: gr-qcCreated: 2026-09-13; Updated: 2026-09-15; Datestamp: 2026-09-15
We investigate the quasinormal spectra and time-domain evolution of scalar, electroMAGNETic, and gravitational perturbations of the Einstein-Bronnikov BLACK HOLE in Einstein gravity coupled to nonlinear electrodynamics. The effective potentials associated with all perturbation sectors are shown to form positive potential barriers that vanish at the event horizon and spatial infinity. Their height increases with the MAGNETic charge, while the scalar perturbation possesses the largest potential barrier. Unlike the Reissner-Nordström BLACK HOLE, axial and polar electroMAGNETic perturbations are characterized by distinct effective potentials, demonstrating the breaking of isospectrality due to nonlinear electrodynamics. Quasinormal frequencies are computed using the sixth-order WKB approximation and the asymptotic iteration method, yielding excellent agreement for both fundamental and higher overtone modes. The oscillation frequencies increase monotonically with the MAGNETic charge, whereas the damping rates exhibit only moderate variations, confirming the linear stability of the Einstein-Bronnikov BLACK HOLE under all perturbations considered. Time-domain profiles display exponentially damped ringdown signals consistent with the frequency-domain analysis. These results demonstrate that nonlinear electrodynamics leaves measurable imprints on BLACK HOLE perturbations and may provide observational signatures for testing regular BLACK HOLE geometries through future gravitational wave observations.
[abstract 53 / 62] (score: 2) - Title: Superradiant Thomson Scattering via Oscillating QuasiparticlesAuthors: Qianyi Ma, Yuhui Xia, Zhenan Wang, Letian Liu, Zhiyan Yang, Xinlu Xu, Xueqing Yan,Comments: 14 pages, 5 figuresSubjects: physics.plasm-phCreated: 2026-09-13; Updated: 2026-09-15; Datestamp: 2026-09-15
The recently proposed concept of generalized superradiance (GS) allows for the generation of coherent radiation without the need for complex compression or prebunching of RELATIVISTIC electrons. However, the quasiparticles in current GS schemes are formed through local electron accumulation and their sizes exceed 100 nm, restricting the achievable radiation wavelength. In this study, we demonstrate a realization of narrow quasiparticles with <10 nm widths through sheet-crossing. When an energy chirped electron beam collides with an intense LASER pulse, lower energy electrons at the front slip back, forming an accelerating quasiparticle. These quasiparticles undergo transverse oscillations within the LASER field, thereby extending GS emission from the Cherenkov regime into the SYNCHROTRON regime. Three-dimensional particle-in-cell simulations indicate the production of gigawatt-class chirped radiation in the 10-100 nm range. The proposed scheme is compatible with existing Thomson scattering facilities, paving the way for the generation of coherent ultrafast radiation.
[abstract 54 / 62] (score: 2) - Title: Photon-induced $J/ψ$ as a linearly polarized probe of collision geometry in RELATIVISTIC heavy-ion collisionsAuthors: STAR Collaboration,Comments: 7 pages, 3 figuresSubjects: nucl-exCreated: 2026-09-13; Updated: 2026-09-15; Datestamp: 2026-09-15
In RELATIVISTIC heavy-ion collisions, the linear POLARIZATION of quasi-real photons can correlate the spin orientation of photon-induced vector mesons with the collision geometry. To explore this sensitivity, we present the first measurement of the decay angular distribution of photon-induced $J/ψ$ with respect to the event plane in heavy-ion collisions with hadronic overlap. The analysis uses Ru+Ru and Zr+Zr collisions at a nucleon--nucleon center-of-mass energy of $\sqrt{s_{\mathrm{NN}}}=200$ GeV recorded by STAR. After correcting for the finite event-plane resolution and subtracting the residual hadronic contribution, we extract a negative second-order modulation, $A_2^{\rm phot} = -0.39 \pm 0.11~(\mathrm{stat.}) \pm 0.04~(\mathrm{sys.})$, for $|y^{ee}|<0.8$, $p_{\mathrm T}^{ee}<0.2~\mathrm{GeV}/c$, and 30--80% centrality. This modulation provides evidence that the $J/ψ$ POLARIZATION is correlated with the event plane, as expected for linearly polarized photons. The observed modulation establishes polarized $J/ψ$ photoproduction as a direct probe of the transverse orientation of the initial collision geometry.
[abstract 55 / 62] (score: 2) - Title: A Comprehensive Analysis of the Relation between Intermittency and Dissipation in Non-Homogeneous Turbulent FlowsAuthors: F. H. Schmitt, J. Peinke, M. Obligado,Comments:Subjects: physics.flu-dynCreated: 2026-09-13; Updated: 2026-09-15; Datestamp: 2026-09-15
A recent study of various turbulent flows showed that intermittency and dissipation exhibit consistent scaling behavior beyond homogeneous isotropic turbulence (HIT). For turbulent wakes, grid turbulence, and a turbulent JET, the dissipation parameter $C_\varepsilon$ and intermittency parameter $μ$ vary while their product remains constant, independently of the Reynolds number $Re_λ$. Here, we extend this result from centerline hot-wire measurements to non-centerline data, including regions with significant shear. We identify two additional relations: $(γ-1)C_\varepsilon$ remains constant, where $γ$ is the absolute inertial-range spectral slope, and $γ$ varies linearly with the Kolmogorov parameter $C_k$. The main constraint is that the large-scale increment probability density function is Gaussian, indicating random large-scale driving. These relations reduce the varying quantities $C_\varepsilon$, $μ$, $γ$, and $C_k$ to three constants and define a turbulence state that can be characterized by any one of these parameters, independently of shear, flow type, or Reynolds number. We further show that, for a given flow configuration, $C_\varepsilon$ depends on $Re_λ$ and turbulence intensity $TI$. Because the four parameters vary over broad ranges around their nominal HIT values, we interpret this framework as a generalization of HIT to inhomogeneous turbulence. Extensive robustness tests show that the results are insensitive to the specific post-processing method. We also analyze their streamwise and spatial evolution and show that a measured $C_\varepsilon$ can be used to predict $μ$, $γ$, and $C_k$ within quantified uncertainty. The framework thus links key leading-order features of turbulence while recovering established HIT trends.
[abstract 56 / 62] (score: 2) - Title: Quasinormal modes of Reissner-Nordström BLACK HOLE from bound state spectrumAuthors: Bo-Yun Zhou, Hao-Yun Ma, Jia-Hui Huang,Comments: 7 pagesSubjects: gr-qcCreated: 2026-09-14; Updated: 2026-09-15; Datestamp: 2026-09-15
We apply a newly proposed bound state method to revisit the computation of gravitational and electroMAGNETic quasinormal modes (QNMs) for Reissner-Nordström BLACK HOLEs (RNBHs). It is found that the method yields QNM frequencies of high accuracy for low-lying modes with overtones $n\leq3$. The accuracy degrades for higher overtones, however, a homotopy deformation to the potential enables us to compute more high overtone modes reliably. It is known that the continued fraction method for computing QNMs of extremal RNBHs differs significantly from that used for nonextremal ones. In contrast, the bound state method demonstrates advantage of simplicity: one only need to account for the definition of tortoise coordinate in the extremal case, and the rest of the computational procedure remains exactly the same as that for the nonextremal case.
[abstract 57 / 62] (score: 2) - Title: Analytical Grad-Shafranov equilibria for prescribed boundaries: shape effects and Shafranov shift reversalAuthors: D. Abate,Comments: 16 pages, 7 figures, to be submitted to Plasma Physics and Controlled FusionSubjects: physics.plasm-phCreated: 2026-09-14; Updated: 2026-09-15; Datestamp: 2026-09-15
A quasi-analytic method is presented for computing Grad--Shafranov equilibria with prescribed plasma boundary shapes: the closed-form basis of Cerfon-Freidberg is combined with an overdetermined system that enforces the boundary condition in a least-squares sense while satisfying the Grad-Shafranov equation exactly in the interior. Three boundary families are studied, covering standard convex tokamak shapes and non-convex star-polygon boundaries spanning a wide range of symmetry order and concavity. For standard tokamak shapes, poloidal beta is insensitive to shaping due to the Solov'ev current profile, while polygon boundaries raise it monotonically with the number of sides, driven by the flat sides compressing flux surfaces toward the axis. For the Shafranov shift, odd-fold boundaries admit a critical concavity below which the geometric centre of the boundary overtakes the MAGNETic axis, reversing the sign of $Δ/a$; no such reversal occurs for even-fold boundaries, and the effect has no analogue among convex shapes.
[abstract 58 / 62] (score: 2) - Title: Riemann Map Operator for Solar Front DiagnosticsAuthors: Olena Podladchikova,Comments: 35 pages, 10 figures. Submitted to Solar PhysicsSubjects: astro-ph.SRCreated: 2026-09-14; Updated: 2026-09-15; Datestamp: 2026-09-15
Identifying a shock from a moving solar brightness front requires relating the observed emission to changes in the plasma state. The Riemann framework describes shocks, rarefactions and other waves as parts of a pattern connecting different states. We present the Riemann Map Operator (RMO), an inverse diagnostic framework implemented as a web application to help observers identify MAGNETohydrodynamic (MHD) shock families from incomplete measurements. RMO tests candidate local connections against conservation laws, entropy requirements and characteristic conditions, while retaining observational uncertainties and model assumptions. We demonstrate the approach with five solar examples and a complementary in-situ comparison. An event combining extreme-ultraviolet (EUV) imaging and spectroscopy admits both fast and slow shock connections within the tested conditions. For an EUV-radio event, we derive an upstream-flow constraint that would exclude ordinary slow shocks within the adopted model, provided both diagnostics sample the same front. A flare-loop benchmark reproduces the published spectral profiles and recovers slow-shock ordering in the isothermal limit. The Solar Orbiter comparison recovers an Alfvenic relation between measured velocity and MAGNETic-field changes. Together, the examples show how RMO connects observations to admissible MHD interpretations and identifies the additional measurements needed to distinguish them.
[abstract 59 / 62] (score: 2) - Title: The WISSH QUASARs project XIII. A multi-epoch study of ultra-fast broad absorption line outflows at cosmic noonAuthors: A. Deconto-Machado, G. Vietri, E. Piconcelli, S. Bisogni, T. Misawa, A. Gargiulo, G. Lanzuisi, A. Travascio, M. Bischetti, L. Zappacosta, E. Bertola, G. Cresci, F. la Franca, M. Gaspari, F. Salvestrini, C. Vignali, A. Luminari, E. Marini, F. Tombesi, A. Bongiorno, S. Carniani, C. Feruglio, F. Fiore, E. Glikman, V. Testa,Comments: Accepted for publication in A&ASubjects: astro-ph.GACreated: 2026-09-14; Updated: 2026-09-15; Datestamp: 2026-09-15
Ultra-fast broad absorption line outflows (uBAL, ~0.1-0.2c) represent some of the most extreme manifestations of QUASAR-driven winds. We aim to investigate the variability of uBALs through their characterisation across different epochs and multiple ionic species. The main goal is to constrain their physical properties, locations, and kinetic powers to evaluate their potential impact on the respective QUASAR host galaxies. We performed a multi-epoch analysis of three hyper-luminous QUASARs from the WISSH sample, namely WISSH53, WISSH56, and WISSH71, at redshifts z=3.628, 4.101, and 3.567, respectively. New and archival spectra, spanning up to ~23 years of monitoring in the observed frame, were used in the analysis. We modeled absorption associated with the CIV transition with Gaussian components, accounting for covering factor variations. A conservative analysis of multi-ion profiles (PV, Lyalpha, NV, SiIV) was also performed, considering the same uBAL velocity as CIV. We derived ionic column density, as well as ionisation parameters, which allowed us to estimate lower and upper limits on distances and kinetic powers of the outflows. The CIV uBALs in the three sources exhibit velocities up to ~0.2c and show significant variability across epochs, likely driven by changes in ionisation state and/or transverse gas motion. The analysis of the multiple troughs highlights the dominant mechanisms causing variability and enables the derivation of robust lower and upper limits of the physical and energetic properties of the outflows. Outflow distances are constrained from the broad line region (BLR) radius (~1 pc) up to a few hundred parsecs, and kinetic powers of individual troughs reach up to ~25% of the QUASAR bolometric luminosity, in the most extreme cases. Our results demonstrate that extreme outflows such as the uBALs are able to inject sufficient kinetic energy to affect the host medium.
[abstract 60 / 62] (score: 2) - Title: A Self-consistent Model for the Generation of Coronal Condensations: The Effects of Turbulent Wave DissipationAuthors: M. McMurdo, V. Jercic, T. Van Doorsselaere, C. Froment,Comments: 15 pages, 10 figuresSubjects: astro-ph.SRCreated: 2026-09-14; Updated: 2026-09-15; Datestamp: 2026-09-15
Prominences and coronal rain are two manifestations of coronal condensations whose formation mechanisms remain only partially understood. While previous studies have explored how localised steady or stochastic heating can trigger thermal instability and condensations, the role of wave driven energy transport and dissipation has not been extensively investigated. In the solar atmosphere, Alfven and kink waves are an abundant source of energy capable of contributing both to coronal heating and plasma structuring, making them compelling candidates in the formation processes of the structures we observe in the corona. We aim to explore how Alfven and kink wave energy and their dissipation influence the formation and evolution of condensations in coronal MAGNETic structures. In particular, we investigate each waves role independently of parameterised external heating mechanisms to isolate whether either wave can trigger condensations. We perform 2.5D simulations using the open source MPI AMRVAC code extended with the newly developed UAWSoM module. This module self consistently evolves Alfven and kink wave energy and their feedback on the plasma through wave pressure and heating terms. We examine the conditions under which condensations form, their morphology, and their dynamical evolution. Our results show that for our range of parameters, in 2.5D MHD, Alfven waves did not trigger the formation of prominences or condensations. We find that if the radius of the fine scale structures supporting the kink waves is of the order of 100 km, then kink waves can trigger coronal rain that differs considerably in its morphology from coronal rain triggered by parameterised heating functions. Through the use of UAWSoM, we have established that Alfven and kink waves leave distinct thermodynamic signatures on coronal loops, given the same wave energy injection.
[abstract 61 / 62] (score: 2) - Title: Klein Tunneling of Dirac FERMIons through ElectroMAGNETic BarriersAuthors: Lingang Zhang, Hua Chen,Comments: 6 pages, 3 figuresSubjects: quant-phCreated: 2026-09-14; Updated: 2026-09-15; Datestamp: 2026-09-15
The Lorentz covariance of RELATIVISTIC Dirac equations serves as a fundamental principle underlying the laws of electroMAGNETism across different inertial frames. Exploiting the covariance, we obtain the general solutions for Dirac fermions under both the in-plane electric $\boldsymbol{E}$ and perpendicular MAGNETic $\boldsymbol{B}$ fields, which reduce to either a MAGNETic or electric field in the inertial frame with drift velocity along the $\boldsymbol{E}\times\boldsymbol{B}$ direction. This dichotomy defines the MAGNETic and electric regimes, separated by the critical field ratio $E/B=v_\text{F}$ with $v_\text{F}$ denoting the FERMI velocity of Dirac fermions. Using these solutions, we revisit Klein tunneling through a heterojunction with generalized electroMAGNETic potentials. In the MAGNETic regime, the transmission exhibits oscillations governed by the Fabry-Pérot interference. In the electric regime, perfect transmission occurs at normal incidence in the drifted frame. The interference phase is further analyzed in terms of the solid angles on the Bloch sphere, providing a geometric interpretation of Klein tunneling. Finally, we briefly discuss the relation between the tilting of Dirac cones and the in-plane electric field, establishing the correspondence of the undertilted and overtilted cases to the MAGNETic and electric regimes, respectively. Our findings reveal the manipulation of Klein tunneling by electroMAGNETic fields, offering a theoretical basis for designing novel electronic devices.
[abstract 62 / 62] (score: 2) - Title: The Multiphase CGM in the Epoch of Reionization: CII and CIV absorbers around [OIII] EmittersAuthors: C. Piscitelli, V. D'Odorico, M. Galbiati, M. Bischetti, G. Cupani, R. Dutta, S. Cantalupo, S. Di Stefano, S. T. Guida, K. Knudsen, C. Mazzucchelli, L. Paquereau, L. Pentericci, R. Rana, F. Ricci, F. Salvestrini, A. Tortosa, A. Travascio, C. Vignali, L. Zappacosta,Comments: Submitted to A&A, version revised after first referee reportSubjects: astro-ph.GACreated: 2026-09-14; Updated: 2026-09-15; Datestamp: 2026-09-15
We investigate the multiphase circumgalactic medium (CGM) during the Epoch of Reionization (EoR, $z>6$) by cross-correlating cool- CII and warm-ionized CIV absorption systems with star-forming [OIII] emitters. JWST/NIRCam wide-field slitless spectroscopy from the EIGER survey is combined with medium- and high-resolution optical/NIR spectra of six background QUASARs, including new VLT/X-Shooter observations of PSO J159-02. We analyze the relation between 16 CII and 14 CIV absorbers ($\log(N) > 13.0$) and 136 galaxies, within an impact parameter of R$_{\perp} \leq$ 1000 pkpc and a line-of-sight separation of $Δv \leq 500$ km/s. We detect a statistically significant excess of both ions around galaxies compared to a randomized background. We observe that the CIV covering fraction remains enhanced up to $\sim 1$ pMpc, whereas CII drops to the background level beyond $\sim 0.5$ pMpc, demonstrating that the warm-ionized phase is more spatially extended than cooler gas. Jointly, the 3D galaxy-absorber spatial clustering is significantly weaker than the galaxy-galaxy auto-correlation. This provides direct physical evidence that early carbon enrichment is not confined to the virial radius of massive star-forming systems; rather, a substantial fraction of these metals permeates the diffuse intergalactic medium (IGM) or is injected by a widespread population of faint, undetected dwarf galaxies. Finally, we note a rapid radial decline of the CIV covering fraction compared with lower redshift samples at $z<2$ and $z\sim3-4$ pointing out an evolving CGM ionization structure where early metals reside predominantly in lower ionization states. In conclusion, we determine a conservative lower limit for the observed carbon mass of $\rm M_{CII + CIV} \geq 2.8 \times 10^6 \, M_{\odot}$ within 300 pkpc.
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