Current date: 2026-09-22
Setting default datestamp limit: 0
Datestamp limit: 2026-09-22 (0 days ago)
Created/updated limit: 2026-09-15 (7 days ago)
Found keywords_cs.datFound keywords_cis.dat
Suggested sets: physics, physics:astro-ph, physics:gr-qc, physics:physics
Setting default set: physics
OAI-PMH request: http://export.arxiv.org/oai2?verb=ListRecords&from=2026-09-22&until=2026-09-22&set=physics&metadataPrefix=arXiv
Scoring abstracts
Number of records retrieved: 1300
Keyword score statistics
score 21 -- 1 abstracts
score 15 -- 1 abstracts
score 12 -- 1 abstracts
score 11 -- 1 abstracts
score 10 -- 1 abstracts
score 8 -- 1 abstracts
score 7 -- 4 abstracts
score 6 -- 3 abstracts
score 5 -- 5 abstracts
score 4 -- 2 abstracts
score 3 -- 13 abstracts
score 2 -- 37 abstracts
in total -- 70 abstracts
Articles that appeared on 2026-09-22
-
[abstract 1 / 70] Wow! (score: 21)
- Title: Broadband multiwavelength properties of the archetypal BLAZAR 3C 279 during the 2017 Event Horizon Telescope campaignAuthors: G. Principe, J. C. Algaba, E. Aviano, W. Y. Cheong, K. Hada, D. Haggard, A. Hahn, S. G. Jorstad, E. V. Kravchenko, Y. Kovalev, S. S. Lee, M. Lisakov, S. Markoff, A. P. Marscher, M. Sasada, P. Voitsik, Kazunori Akiyama, Ezequiel Albentosa-Ruiz, Antxon Alberdi, Walter Alef, Richard Anantua, Eleni Antonopoulou, Keiichi Asada, Rebecca Azulay, Anne-Kathrin Baczko, David Ball, Bidisha Bandyopadhyay, John Barrett, Michi Baubock, Bradford A. Benson, Dan Bintley, Lindy Blackburn, Raymond Blundell, Katherine L. Bouman, Geoffrey C. Bower, Michael Bremer, Roger Brissenden, Silke Britzen, Avery E. Broderick, Dominique Broguiere, Thomas Bronzwaer, Sandra Bustamante, Douglas F. Carlos, John E. Carlstrom, Andrew Chael, Chi-kwan Chan, Dominic O. Chang, Koushik Chatterjee, Ming-Tang Chen, Yongjun Chen, Xiaopeng Cheng, Paul Chichura, Ilje Cho, Nicholas S. Conroy, John E. Conway, Thomas M. Crawford, Geoffrey B. Crew, Alejandro Cruz-Osorio, Yuzhu Cui, Brandon Curd, Rohan Dahale, Jordy Davelaar, Joost de Kleuver, Mariafelicia De Laurentis, Roger Deane, Jason Dexter, Vedant Dhruv, Indu K. Dihingia, Sheperd S. Doeleman, Sergio A. Dzib, Razieh Emami, Heino Falcke, Joseph Farah, Vincent L. Fish, Edward Fomalont, H. Alyson Ford, Marianna Foschi, Raquel Fraga-Encinas, William T. Freeman, Per Friberg, Christian M. Fromm, Antonio Fuentes, Peter Galison, Charles F. Gammie, Roberto Garcia, Olivier Gentaz, Boris Georgiev, Ciriaco Goddi, Roman Gold, Arturo I. Gomez-Ruiz, Jose L. Gomez, Minfeng Gu, Mark Gurwell, Ronald Hesper, Dirk Heumann, Luis C. Ho, Paul Ho, Mareki Honma, Chih-Wei L. Huang, Lei Huang, David H. Hughes, Shiro Ikeda, C. M. Violette Impellizzeri, Makoto Inoue, Sara Issaoun, David J. James, Buell T. Jannuzi, Michael Janssen, Britton Jeter, Wu Jiang, Alejandra Jimenez-Rosales, Michael D. Johnson, Adam C. Jones, Abhishek V. Joshi, Taehyun Jung, Tomohisa Kawashima, Garrett K. Keating, Mark Kettenis, Dong-Jin Kim, Jae-Young Kim, Jongsoo Kim, Junhan Kim, Motoki Kino, Jakob Knollmüller, Jun Yi Koay, Prashant Kocherlakota, Yutaro Kofuji, Patrick M. Koch, Shoko Koyama, Carsten Kramer, Joana A. Kramer, Michael Kramer, Thomas P. Krichbaum, Cheng-Yu Kuo, Noemi La Bella, Deokhyeong Lee, Aviad Levis, Shaoliang Li, Zhiyuan Li, Rocco Lico, Greg Lindahl, Michael Lindqvist, Jun Liu, Kuo Liu, Elisabetta Liuzzo, Wen-Ping Lo, Andrei P. Lobanov, Laurent Loinard, Colin J. Lonsdale, Amy E. Lowitz, Ru-Sen Lu, Nicholas R. MacDonald, Jirong Mao, Nicola Marchili, Daniel P. Marrone, Alan P. Marscher, Ivan Marti-Vidal, Satoki Matsushita, Lynn D. Matthews, Lia Medeiros, Karl M. Menten, Hugo Messias, Izumi Mizuno, Yosuke Mizuno, Joshua Montgomery, Kotaro Moriyama, Monika Moscibrodzka, Wanga Mulaudzi, Cornelia Müller, Hendrik Müller, Alejandro Mus, Gibwa Musoke, Ioannis Myserlis, Hiroshi Nagai, Neil M. Nagar, Dhanya G. Nair, Masanori Nakamura, Gopal Narayanan, Iniyan Natarajan, Antonios Nathanail, Santiago Navarro Fuentes, Joey Neilsen, Chunchong Ni, Andy Nilipour, Michael A. Nowak, Hiroki Okino, Hector Ra. l Olivares Sanchez, Feryal Ozel, Daniel C. M. Palumbo, Georgios Filippos Paraschos, Jongho Park, Harriet Parsons, Nimesh Patel, Ue-Li Pen, Dominic W. Pesce, Vincent Pietu, Alexander Plavin, Aleksandar PopStefanija, Oliver Porth, Ben Prather, Dimitrios Psaltis, Hung-Yi Pu, Alexandra Rahlin, Venkatessh Ramakrishnan, Ramprasad Rao, Mark G. Rawlings, Angelo Ricarte, Luca Ricci, Bart Ripperda, Jan Roder, Freek Roelofs, Cristina Romero-Ca. izales, Eduardo Ros, Arash Roshanineshat, Helge Rottmann, Alan L. Roy, Ignacio Ruiz, Chet Ruszczyk, Kazi L. J. Rygl, Leon D. S. Salas, Salvador Sanchez, David Sanchez-Argüelles, Miguel Sanchez-Portal, Ali SaraerToosi, Kaushik Satapathy, Saurabh, Tuomas Savolainen, Karl-Friedrich Schuster, Zhiqiang Shen, Sasikumar Silpa, Randall Smith, Bong Won Sohn, Jason SooHoo, Kamal Souccar, Joshua S. Stanway, He Sun, Alexandra J. Tetarenko, Paul Tiede, Remo P. J. Tilanus, Michael Titus, Kenji Toma, Pablo Torne, Teresa Toscano, Efthalia Traianou, Sascha Trippe, Matthew Turk, Ilse van Bemmel, Bram van den Berg, Huib Jan van Langevelde, Daniel R. van Rossum, Sebastiano D. von Fellenberg, Jesse Vos, Jan Wagner, Zhiren Wang, Derek Ward-Thompson, John Wardle, Jasmin E. Washington, Jonathan Weintroub, Maciek Wielgus, Kaj Wiik, Michael F. Wondrak, George N. Wong, Jompoj Wongphexhauxsorn, Qingwen Wu, Paul Yamaguchi, Aristomenis Yfantis, Doosoo Yoon, Andre Young, Ziri Younsi, Wei Yu, Feng Yuan, Ye-Fei Yuan, Ai-Ling Zeng, J. Anton Zensus, Shuo Zhang, Guang-Yao Zhao, J. Abhir, A. Abhishek, V. A. Acciari, A. Aguasca-Cabot, I. Agudo, I. Albanese, T. Aniello, S. Ansoldi, L. A. Antonelli, A. Arbet Engels, C. Arcaro, T. T. H. Arnesen, A. Babic, C. Bakshi, U. Barres de Almeida, J. A. Barrio, L. Barrios-Jimenez, I. Batkovic, J. Becerra Gonz. lez, W. Bednarek, E. Bernardini, J. Bernete, A. Berti, J. Besenrieder, C. Bigongiari, A. Biland, O. Blanch, G. Bonnoli, Ž. Bošnjak, E. Bronzini, I. Burelli, A. Campoy-Ordaz, A. Carosi, R. Carosi, M. Carretero-Castrillo, A. J. Castro-Tirado, D. Cerasole, G. Ceribella, A. Cervi. o, Y. Chai, G. Chon, J. L. Contreras, J. Cortina, S. Covino, P. Da Vela, F. Dazzi, A. De Angelis, B. De Lotto, M. Delfino, J. Delgado, C. Delgado Mendez, F. Di Pierro, R. Di Tria, L. Di Venere, A. Dinesh, D. Dominis Prester, A. Donini, D. Dorner, M. Doro, L. Eisenberger, D. Elsaesser, L. Foffano, L. Font, F. Fr. as Garcia-Lago, S. Fr. se, Y. Fukazawa, S. Gasparyan, M. Gaug, J. G. Giesbrecht Paiva, N. Giglietto, F. Giordano, P. Gliwny, T. Gradetzke, R. Grau, J. G. Green, P. Günther, D. Hadasch, G. Harutyunyan, J. Herrera Llorente, D. Hrupec, D. Israyelyan, J. Jahanvi, I. Jimenez Martinez, J. Jimenez Quiles, S. Kankkunen, T. Kayanoki, J. Konrad, P. M. Kouch, H. Kubo, J. Kushida, M. L. inez, A. Lamastra, E. Lindfors, S. Lombardi, F. Longo, R. Lopez-Coto, M. Lopez-Moya, A. Lopez-Oramas, S. Loporchio, L. LuliLc, P. Majumdar, M. Makariev, M. Mallamaci, G. Maneva, M. Manganaro, S. Mangano, K. Mannheim, S. Marchesi, M. Mariotti, M. Martinez, P. Maruševec, D. Mazin, S. Menchiari, J. M. ndez Gallego, S. Menon, D. Miceli, J. M. Miranda, R. Mirzoyan, M. Molero Gonzalez, E. Molina, H. A. Mondal, A. Moralejo, C. Nanci, A. Negro, V. Neustroev, C. Nigro, L. Nikolic, K. Noda, S. Nozaki, A. Okumura, J. Otero-Santos, S. Paiano, D. Paneque, R. Paoletti, J. M. Paredes, M. Peresano, M. Persic, M. Pihet, G. Pirola, F. Podobnik, P. G. Prada Moroni, E. Prandini, M. Rib., J. Rico, A. Roy, N. Sahakyan, F. G. Saturni, F. Schiavone, K. Schmitz, A. Sciaccaluga, G. Silvestri, A. Simongini, J. Sitarek, V. Sliusar, D. Sobczynska, A. Stamerra, J. Striškovic, D. Strom, Y. Suda, M. Takahashi, R. Takeishi, J. Tartera Barber., P. Temnikov, T. Terzic, M. Teshima, A. Tutone, S. Ubach, S. Ventura, G. Verna, I. Viale, A. Vigliano, C. F. Vigorito, E. Visentin, V. Vitale, M. Vorbrugg, I. Vovk, R. Walter, C. Walther, F. Wersig, P. K. H. Yeung, A. Acharyya, F. Aharonian, H. Ashkar, M. Backes, M. Barnard, Y. Becherini, M. B. ttcher, J. Bolmont, B. Bruno, T. Bylund, S. Casanova, M. Chernyakova, J. O. Chibueze, O. Chibueze, B. Cornejo, J. Damascene Mbarubucyeye, I. D. Davids, J. de Assis Scarpin, M. de Naurois, A. Dmytriiev, K. Egberts, S. Fegan, K. Feijen, M. D. Filipovic, G. Fontaine, S. Gabici, J. F. Glicenstein, P. Goswami, L. Heckmann, B. He., M. Holler, D. Horns, E. Kasai, K. Katarzynski, D. Kerszberg, B. Kh. lifi, K. Kosack, R. G. Lang, S. Lazarevic, P. Liniewicz, A. Luashvili, D. Malyshev, D. Malyshev, M. G. F. Mayer, M. Meyer, A. Mikhno, E. Moulin, H. Ndiyavala, J. Niemiec, P. Pichard, T. Preis, G. Pühlhofer, A. Quirrenbach, A. Reimer, O. Reimer, I. Reis, B. Rudak, K. Sabri, V. Sahakian, A. Santangelo, M. Sasaki, I. Shebalkova, W. Si Said, L. Stawarz, R. Steenkamp, T. Tanaka, G. L. Taylor, R. Terrier, Y. Tian, M. Tluczykont, C. Venter, J. Vink, V. Voitsekhovskyi, S. J. Wagner, A. Wierzcholska, M. Zacharias, A. A. Zdziarski,Comments: 29 pages, 13 figures, published in Astronomy & Astrophysics on September 4, 2026Subjects: astro-ph.HE astro-ph.GACreated: 2026-09-21; Updated: 2026-09-22; Datestamp: 2026-09-22
The archetypal BLAZAR 3C 279 hosts a prominent RELATIVISTIC JET and exhibits strong broadband variability across the electroMAGNETic spectrum. In April 2017, the Event Horizon Telescope (EHT) observed 3C 279, alongside one of the most extensive quasi-simultaneous multiwavelength (MWL) campaigns ever conducted. With the aim of investigating the physical processes governing 3C 279, we analyzed individual observations and multiband light curves, and constructed a new quasi-simultaneous MWL spectrum. We also performed phenomenological modeling using the turbulent extreme multi-zone (TEMZ) model to constrain the fundamental physical properties of the source. The EHT observations reveal a clear flux increase in the innermost core between April 5 and 11, 2017. Over a broader timescale, radio measurements at longer wavelengths show concurrent enhancements in core flux and POLARIZATION around mid-April, coinciding with the ejection of a superluminal knot. Record UV-optical flares with strong POLARIZATION variability occurred in late March, followed by gamma-ray activity that declined before the end of the EHT observing period. During this interval, the source remained in a low X-ray state and showed no detectable VHE emission. The TEMZ modeling suggests that the broadband spectrum and variability of 3C 279 can be explained within a JET scenario in which turbulent plasma cells are compressed by a stationary conical shock. However, alternative interpretations, such as MAGNETic RECONNECTion or a moving shock-in-JET event, remain plausible. This coordinated MWL campaign advances our understanding of the origin of JET and gamma-ray emission in 3C 279, while also providing a comprehensive publicly available dataset that will serve as a valuable reference for future studies.
[abstract 2 / 70] Wow! (score: 15) - Title: Multi-wavelength Behaviour and Lepto-hadronic Modeling of PKS 0215+015 Around the Epoch of IceCube-220225AAuthors: Athira M Bharathan, Markus Böttcher,Comments: Accepted for publication in Journal of High Energy AstrophysicsSubjects: astro-ph.HECreated: 2026-09-21; Updated: 2026-09-22; Datestamp: 2026-09-22
The detection of high-energy astrophysical neutrinos has opened a new avenue for identifying cosmic particle accelerators. Blazars, ACTIVE GALACTIC NUCLEi (AGN) with RELATIVISTIC JETs oriented close to the observer's line of sight, are promising sites of hadronic interactions capable of producing PeV-scale neutrinos. We investigate the flat-spectrum radio QUASAR (FSRQ) PKS~0215+015 ($z \simeq 1.715$), positionally consistent with the \textit{IceCube-220225A} neutrino event of estimated energy $\sim$154~TeV. We combine \textit{FERMI}-LAT $γ$-ray data with SWIFT-XRT and SWIFT-UVOT observations to characterise the source around the neutrino epoch. PKS~0215+015 exhibited pronounced $γ$-ray, X-ray and optical activity in early 2022, consistent with a disturbance propagating along the JET. We construct broadband spectral energy distributions (SEDs) for the flaring interval and model them using leptonic and lepto-hadronic frameworks. The SED is well reproduced by a leptonic model comprising SYNCHROTRON, SYNCHROTRON self-Compton and external Compton emission, indicating that electron processes dominate. A co-accelerated proton population remains radiatively subdominant but requires a proton kinetic luminosity roughly two orders of magnitude above equipartition with the MAGNETic field. The predicted neutrino flux is well below that implied by a single \textit{IceCube-220225A}-like detection. Independent analysis of short-term $γ$-ray variability yields an emission-region size consistent with the SED fit, supporting the model's physical self-consistency. We discuss the temporal and energetic plausibility of the association between PKS~0215+015 and \textit{IceCube-220225A} and implications for future multimessenger studies of high-redshift FSRQs.
[abstract 3 / 70] Wow! (score: 12) - Title: A Linear Instability and Damping in the Acoustic Dispersion Relation of Fluids Subject to Inverse Compton DragAuthors: Yiting Wang, Sebastian Heinz, Vladimir Zhdankin,Comments: 6 figuresSubjects: astro-ph.HE physics.plasm-phCreated: 2026-09-20; Updated: 2026-09-22; Datestamp: 2026-09-22
Radiation drag from inverse-Compton scattering of an external radiation field changes the acoustic dispersion relation of a RELATIVISTIC fluid. We derive the linear dispersion relation and show that, depending on the electron distribution and fluid sound speed, radiation drag either damps both modes or damps one while driving the other unstable. The unstable growth is robust at short wavelengths but slow and overdamped at long wavelengths, where the linear analysis is limited by the background acceleration. The resulting growth and damping rates are of order the bulk radiative acceleration rate, so whenever radiation drag is important for the background flow, its effects on fluid perturbations are also important. A purely damped region exists for a wide range of parameters. Radiation drag also makes acoustic waves dispersive: The phase speed deviates from the ordinary sound speed at longer wavelengths, and approaches the sound speed at short wavelengths. We validate the derived rates using special-RELATIVISTIC hydrodynamic simulations. We apply the derived relation to astrophysical JETs such as GAMMA-RAY BURSTs, BLAZARs in the broad-line region of the host ACTIVE GALACTIC NUCLEus, and QUASAR JETs traveling through the CMB and galactic radiation field. We find that the derived instability, damping and dispersion may be relevant across a range of RELATIVISTIC outflow conditions.
[abstract 4 / 70] Wow! (score: 11) - Title: Second Repeating FRB 180814.J0422+73: Ten-year FERMI-LAT Upper limits and ImplicationsAuthors: Yu-Han Yang, Bin-Bin Zhang, Bing Zhang,Comments: 9 pages, 3 figures, 1 table. Accepted version, published in ApJL 875, L19 (2019)Subjects: astro-ph.HECreated: 2026-09-19; Updated: 2026-09-22; Datestamp: 2026-09-22
The second repeating fast radio burst source, FRB 180814.J0422+73, was detected recently by the CHIME collaboration. We use the ten-year FERMI Large Area Telescope (LAT) archival data to place a flux upper limit in the energy range of 100 MeV-10 GeV at the position of the source, which is $\sim {1.1\times 10^{-11}}$ erg cm$^{-2}$ s$^{-1}$ for a six-month time bin on average, and $\sim {2.4\times 10^{-12}}$ erg cm$^{-2}$ s$^{-1}$ for the entire ten-year time span. For the maximum redshift of $z=0.11$, the ten-year upper limit of luminosity is $\sim {7.3\times 10^{43}}$ erg s$^{-1}$. We utilize these upper limits to constrain the FRB progenitor and central engine. For the rotation-powered young MAGNETar model, the upper limits can pose constraints on the allowed parameter space for the initial rotational period and surface MAGNETic field of the MAGNETar. We also place significant constraints on the kinetic energy of a RELATIVISTIC external shock wave, ruling out the possibility that there existed a GAMMA-RAY BURST (GRB) beaming towards Earth during the past ten years as the progenitor of the repeater. The case of an off-beam GRB is also constrained if the viewing angle is not much greater than the JET opening angle. All these constraints are more stringent if FRB 180814.J0422+73 is at a closer distance.
[abstract 5 / 70] Wow! (score: 10) - Title: Observational Evidence of an Internal Shock Collision in the Relativistic Jet of the Nearby Radio Galaxy 3C 111Authors: Kenzo Kawamura, Motoki Kino, Mareki Honma, Kazuhiro Hada, Paul Tiede, Evgeniya Kravchenko, Marcello Giroletti, Rocco Lico, Kazunori Akiyama, Mieko Takamura, Filippo D'Ammando, Monica Orienti, Gabriele Giovannini, Fumie Tazaki, Bong Won Sohn, Salvatore Buttaccio, Lang Cui, Giuseppe Maccaferri, Andrea Melis, Alexey Melnikov, Carlo Migoni, Matteo Stagni, Kiyoaki Wajima, Takeshi Sakai,Comments: 21 pages, 13 figures. Accepted for publication in The Astrophysical JournalSubjects: astro-ph.HE astro-ph.GACreated: 2026-09-20; Updated: 2026-09-22; Datestamp: 2026-09-22
We report 10 epochs of 22 GHz East Asia To Italy: Nearly Global VLBI (EATING VLBI) observations of the nearby RADIO GALAXy 3C~111 obtained from 2020 to 2023. Combined with VLBA data at 15 and 43 GHz, these observations yield a 64-epoch, multi-frequency sequence of high-resolution radio images. We used high-resolution Bayesian Stokes~I imaging and Gaussian component modeling to derive light curves and knot kinematics. We find evidence that a faster, later-emitted knot catches up with a slower, earlier knot at a deprojected distance of about 10 pc from the central engine. The knot component responsible for this interaction propagated at RELATIVISTIC speed and exhibited a rise-and-decay evolution over approximately six months. The Stokes~I flux evolution supports the internal shock interpretation, while archival POLARIZATION images reveal a temporary increase in fractional linear POLARIZATION in the interaction region near the Stokes~I flux maximum. The timing of the 2021 GeV flare suggests that this earlier high-energy event is more naturally associated with activity near the core. These results provide direct evidence for an internal shock in an ACTIVE GALACTIC NUCLEus JET and support a hybrid picture in which internal and standing shocks coexist in RELATIVISTIC JETs and may play different roles in their variability.
[abstract 6 / 70] Wow! (score: 8) - Title: Particle Acceleration in Stratified 2D MRI Turbulence: From Reconnection to First- and Second-Order FERMI and Shear AccelerationAuthors: Astor Sandoval, Mario Riquelme, Jorge Cuadra,Comments:Subjects: astro-ph.HE physics.plasm-phCreated: 2026-09-21; Updated: 2026-09-22; Datestamp: 2026-09-22
Low-luminosity accretion disks around BLACK HOLEs are weakly collisional, potentially enabling nonthermal particle acceleration. Local two-dimensional particle-in-cell simulations of the stratified MAGNETorotational instability (MRI) in pair plasmas by Sandoval et al. (2024; hereafter S24) revealed nonthermal populations with maximum energies proportional to the scale-separation ratio $ω_{c,0}/Ω_0$, where $ω_{c,0}$ and $Ω_0$ are the initial particle cyclotron and Keplerian frequencies, respectively. We identify the acceleration mechanisms involved and quantify their scale-separation dependence. Acceleration occurs primarily within large-scale current sheets associated with an MRI dynamo. Particles are initially injected by non-ideal electric fields during RECONNECTion driven by plasmoid splitting, attaining energies independently of scale separation. They subsequently undergo rapid first-order FERMI-like acceleration occurring within converging flows between newly formed, separating plasmoids. During this stage, energies grow at a rate proportional to the instantaneous non-RELATIVISTIC cyclotron frequency, independently of $ω_{c,0}/Ω_0$. This fast acceleration rate implies a maximum energy proportional to $ω_{c,0}/Ω_0$. Particles then continue interacting repeatedly with plasmoids, undergoing slower, predominantly second-order FERMI acceleration, with a subdominant contribution from shear acceleration. This stage increases particle energies by only a factor of {\it a few} over several orbits, regardless of $ω_{c,0}/Ω_0$. The combination of these three stages implies a maximum energy proportional to $ω_{c,0}/Ω_0$, explaining the scaling found by S24 and suggesting that the MRI may accelerate particles to ultraRELATIVISTIC energies in low-luminosity disks. Testing these results in three dimensions remains an important next step.
[abstract 7 / 70] Wow! (score: 7) - Title: Migration Traps as Variability Attractors. I. Optical/UV Signatures of Embedded Stellar-Mass Black Holes in Active Galactic Nucleus DisksAuthors: Jing-Tong Xing, Tong Liu, Mouyuan Sun, Ya-Ping Li, Shuying Zhou, Zhen-Yi Cai, Da-Bin Lin, Jian-Min Wang,Comments: 25 pages, 7 figures, 1 table, accepted for publication in ApJSubjects: astro-ph.GA astro-ph.HECreated: 2026-09-20; Updated: 2026-09-22; Datestamp: 2026-09-22
We investigate whether embedded stellar-mass BLACK HOLEs (sBHs) in ACTIVE GALACTIC NUCLEus (AGN) disks can leave observable optical/UV variability signatures through migration-trap-driven MAGNETic heating. This mechanism operates when sBHs migrating toward torque-balance radii pile up near migration traps, triggering localized, stochastic MAGNETic RECONNECTion that heats the disk atmosphere. It is potentially important because it provides a physical source of non-coronal disk heating and directly links optical/UV continuum variability to otherwise hidden compact-object populations. By coupling a one-dimensional sBH population synthesis model with a corona-heated accretion-disk reprocessing variability framework, we show that migration traps concentrate sBHs at preferred radii and generate localized, stochastic RECONNECTion heating. The resulting heating is self-regulated: sBH pile-ups enhance the RECONNECTion rate, while gap opening reduces the local gas density and partially suppresses the RECONNECTion power. This heating produces excess short-timescale optical/UV variability, flattened short-term structure functions, and deviations from the standard $τ\proptoλ^{4/3}$ lag-wavelength relation, which describes the time delay between variability at different wavelengths for a standard thin accretion disk. These signatures are strongest at low-to-moderate Eddington ratios, and related observations could provide indirect evidence for embedded compact-object populations in AGN disks.
[abstract 8 / 70] Wow! (score: 7) - Title: Direct imaging of sub-parsec binary SMBHs in the central galaxy of the NGC 5044 groupAuthors: Francesco Ubertosi, Gerrit Schellenberger, Ewan O'Sullivan, Laurence P. David, William Forman, Simona Giacintucci, Christine Jones, Kamlesh Rajpurohit, Tiziana Venturi, Jan Vrtilek,Comments: Under review at Nature Communications. This is the non-peer-reviewed version of the manuscriptSubjects: astro-ph.GACreated: 2026-09-18; Updated: 2026-09-22; Datestamp: 2026-09-22
Binary ACTIVE GALACTIC NUCLEi (AGN) consist of two supermassive BLACK HOLEs (SMBHs) hosted in a single galaxy that are simultaneously accreting gas. These systems are key to understanding hierarchical galaxy evolution and represent prime targets for low-frequency gravitational wave (GW) experiments. However, binary AGN remain extremely rare: only a handful are confirmed at separations of a few hundred parsecs, and just one pc-scale binary - in an elliptical galaxy at the center of a galaxy cluster - has been securely and visually identified. Direct imaging of sub-parsec binary AGN, the final stage before the GW regime, has so far been missing. Here we report on Very Long Baseline Array (VLBA) observations of NGC 5044, the central galaxy of the X-ray brightest galaxy group. This galaxy is known to exhibit pc-scale radio JETs nearly orthogonal to two older AGN outbursts. The 4.9, 8.4, 15.2, and 23.6 GHz VLBA images reveal two compact, flat-spectrum, and variable radio cores separated by just 0.38 parsec at the heart of the galaxy, forming the tightest directly imaged binary AGN known by an order of magnitude. This discovery suggests that the older outbursts may have been powered by JETs from the secondary core, without invoking any reorientation of the primary JET axis. More broadly, comparison with other systems points to massive, cluster-central elliptical galaxies being promising targets to search for binary SMBHs.
[abstract 9 / 70] Wow! (score: 7) - Title: LoTSS of dual AGN: enhanced detectability and prospects for a systematic searchAuthors: Q. D'Amato, F. Mannucci, E. De Rubeis, I. Prandoni, A. De Rosa, M. Scialpi, M. Kunert-Bajraszewska, A. Janiuk, A. Krauze, L. Battistini, E. Bertola, C. Bracci, A. Chakraborty, M. Ceci, C. Cicone, G. Cresci, A. Marconi, C. Marconcini, E. Nardini, M. Parvatikar, A. Peca, K. Rubinur, P. Severgnini, C. Spingola, L. Ulivi, G. Venturi, C. Vignali, M. V. Zanchettin,Comments: 14 pages, 5 figures, 4 table. Accepted for publication in A&ASubjects: astro-ph.GA astro-ph.HECreated: 2026-09-18; Updated: 2026-09-22; Datestamp: 2026-09-22
Context: Dual ACTIVE GALACTIC NUCLEi (DAGN) - systems of two accreting supermassive BLACK HOLEs at kpc-scale separations - trace galaxy mergers and are the progenitors of gravitational-wave sources targeted by pulsar timing arrays and the upcoming Laser Interferometer Space Antenna. However, their radio properties remain poorly constrained, particularly at high redshift. Aims: We demonstrate the detectability of high-redshift DAGN at 144 MHz through sub-arcsec imaging of the LOFAR Two-metre Sky Survey (LoTSS) and characterize their low-frequency radio properties. Methods: We cross-matched 92 spectroscopically confirmed DAGN (z > 0.3, projected separation r_p < 30 kpc) with the LoTSS DR2 catalog and reprocessed international LOFAR telescope (ILT) data for three systems (0.59 < z < 2.39), achieving ~0.3 arcsec resolution at 144 MHz. Multi-frequency analysis and brightness-temperature diagnostics were used to investigate the radio emission. Results: We obtained high-quality ILT images for all three systems. In one source at z = 1.49, both AGN are detected at >5 sigma, making it one of the highest-redshift and faintest radio-detected DAGN. Brightness temperatures confirm AGN-powered emission even in sub-mJy sources. In the other two systems only one AGN is detected; for one, the new data constrain the low-frequency spectrum of a compact steep-spectrum source, indicating that its morphology is driven by JET-ISM interaction rather than the companion galaxy. For the 92 objects sample, the LoTSS detection rate is ~24%, significantly higher than for matched single AGN (~9-10%), suggesting an enhanced detectability of DAGN in the LoTSS. Conclusions: Low-frequency sub-arcsec radio observations provide an efficient, dust-unbiased method to detect and characterize DAGN. This pilot study establishes a benchmark for the forthcoming all-sky ~0.3 arcsec iLoTSS survey and future SKA observations.
[abstract 10 / 70] Wow! (score: 7) - Title: AT2019aalc: An obscured tidal disruption event candidate in an ACTIVE GALACTIC NUCLEus revealed by its first flare?Authors: Ying Gu, Xiao Li, Xue-Guang Zhang, En-Wei Liang,Comments: Accepted for publication in Astronomy & Astrophysics. 6 pages, 4 figuresSubjects: astro-ph.HE astro-ph.GACreated: 2026-09-21; Updated: 2026-09-22; Datestamp: 2026-09-22
AT2019aalc is considered a repeating tidal disruption event (TDE) candidate occurring in an ACTIVE GALACTIC NUCLEus (AGN). In this paper, we highlight previously unnoticed but intriguing features that include a brief optical dimming prior to the rise of the main flare and a significantly lower post-flare luminosity compared to the pre-flare level. By applying a time-dependent obscured TDE model to AT2019aalc, we successfully reproduce its light curves with the tidal disruption of a $1.122_{-0.176}^{+0.246}\rm M_\odot$ main-sequence star by a $1.862_{-0.259}^{+0.255} \times 10^7{\rm M_\odot}$ supermassive BLACK HOLE (SMBH). Both the pre-flare dimming and the reduced post-flare luminosity are attributed to obscuration of the intrinsic AGN emission. The total energy of the event derived from our fit is $1.24\times10^{51}$ ergs and about 0.2 ${\rm M_\odot}$ of debris mass is accreted by the SMBH. In addition, the $g-r$ color of the net flare in AT2019aalc exhibits a continuous reddening trend during the first flare, consistent with a gradual increase in $E(B-V)$ predicted by the obscured TDE model. These results suggest that AT2019aalc can be considered a second member of the recently proposed class of obscured TDE candidates hosted in AGNs. } \keywords{galaxies: active-galaxies: nuclei-QUASARs: supermassive BLACK HOLEs-QUASARs: individual (AT2019aalc)-transients: tidal disruption events.
[abstract 11 / 70] Yes (score: 6) - Title: An extremely bright slow-rising afterglow from an off-axis JET in GRB 260310AAuthors: Yu-Han Yang, Roberto Ricci, Eleonora Troja, Muskan Yadav, Yi-Han Iris Yin, Rubén Sánchez-Ramírez, Brendan O'Connor, Niccoló Passaleva, Alberto J. Castro-Tirado, Hendrik van Eerten, Simone Dichiara, Vincenzo Galluzzi, Narjes Shahamat Dehsorkh, Iván Agudo, Jesús Aceituno, Malte Busmann, María D. Caballero-García, Emilio Fernández-García, Daniel Gruen, Maria Gritsevich, Sergiy Guziy, David Hiriart, You-Dong Hu, Martin Jelínek, Alexander Kutyrev, Alzbeta Malenakova, Filip Novotny, Ignacio Pérez-García, Shashi B. Pandey, Jorma Ryske, Alfredo Sota, Jan Strobl, Hira Waseem, Siyu Wu,Comments: 28 pages, 12 figures, 1 table; ApJL in pressSubjects: astro-ph.HECreated: 2026-09-19; Updated: 2026-09-22; Datestamp: 2026-09-22
We present a multi-wavelength study of GRB 260310A, a nearby long-duration GAMMA-RAY BURST at $z\simeq0.153$ associated with a broad-lined Type Ic SUPERNOVA. Despite its modest prompt gamma-ray output, $E_{γ,\rm iso}\simeq3.5\times10^{50}$ erg, GRB 260310A exhibits one of the brightest afterglows ever observed in the X-ray, optical, and radio bands. Its apparent brightness is not its only remarkable feature. The optical afterglow displays a delayed onset, characterized by a slow rising phase, with slope $α\approx-1$, and a late peak at $\approx$0.1 d. We argue that the combination of weak prompt emission, hard peak energy, and late afterglow onset is naturally explained by a GRB JET viewed off-axis. The radio spectral energy distributions are consistent with SYNCHROTRON radiation and indicate the presence of both reverse- and forward-shock components, thus providing a first test of reverse-shock models in an off-axis geometry. The X-ray afterglow displays a prominent rebrightening, monitored for up to $\approx$68 d with no evidence of spectral evolution. A low level of linear POLARIZATION, $Π\approx1.7\%$, is measured at 15 GHz at $T_0+55$ d and suggests that, at these late times, the forward-shock is the dominant emission component from radio to X-rays. This late-time rebrightening represents a critical test for the two-component JET model. If interpreted as the emergence of a narrow JET core viewed further off-axis, it would imply extreme luminosities and energetics for an on-axis observer.
[abstract 12 / 70] Yes (score: 6) - Title: Gaussian-process evidence for a stochastic-variability transition in the recovering corona of 1ES 1927+654Authors: Lijuan Dong, Dahai Yan,Comments: 12 pages, 4 figures. Accepted for publication in The Astrophysical JournalSubjects: astro-ph.HE astro-ph.GACreated: 2026-09-21; Updated: 2026-09-22; Datestamp: 2026-09-22
We investigate the stochastic X-ray variability of the changing-look ACTIVE GALACTIC NUCLEus 1ES 1927+654 during its 2018--2024 evolution, focusing on the recovery of the X-ray corona after its 2018 collapse. Using XMM-Newton EPIC-pn light curves in the 0.3--2.0 keV and 2.0--10.0 keV bands, we model the variability with Gaussian process (GP) covariance components including Matérn-3/2, damped-random-walk (DRW), stochastically driven damped simple-harmonic-oscillator (SHO), and white-noise terms. Bayesian model comparison reveals an X-ray stochastic-variability transition during the changing-look recovery phase. In the 2019 May 5 observation, the preferred covariance changes from a Matérn-3/2-like state to a DRW-like state within a single continuous exposure. A phenomenological gated-kernel estimate localizes this transition sharply in the hard band at $t_c\simeq23.5~{\rm ks}$, while the soft band shows the same qualitative change over a broader interval. This transition occurs after the X-ray corona had reappeared but before the later pronounced hardening and brightening of the coronal emission, suggesting an early timing-domain signature of disk--corona reconfiguration. Phenomenologically, the dominant variability evolves from a smoother, finite-memory correlated process to a rougher, shorter-memory red-noise process. In the later 2022--2024 observations, SHO-like components associated with the known millihertz QPO show increasing characteristic frequency and quality factor, indicating a faster and more coherent oscillatory component during the QPO-plus-JET phase. GP-based time-domain inference therefore provides a sensitive probe of stochastic-variability changes in recovering AGN coronae.
[abstract 13 / 70] Yes (score: 6) - Title: Geometrically Thin Sub-Eddington AGN Accretion Disks show a suppressed Lyman EdgeAuthors: Ish Kaul, Yan-Fei Jiang, Omer Blaes, Lizhong Zhang,Comments: 13 Pages, 7 figures. Accepted to ApJLSubjects: astro-ph.HE astro-ph.GACreated: 2026-09-18; Updated: 2026-09-22; Datestamp: 2026-09-22
The observed ultraviolet continua of ACTIVE GALACTIC NUCLEi (AGN) generally lack a strong intrinsic HI Lyman edge predicted by classical optically thick accretion disk atmosphere models. We revisit this long-standing problem using our previous sub-Eddington ($L/L_{\rm Edd}\sim 0.03$) geometrically thin 3D accretion disk simulation evolved with gray angle-dependent radiation MAGNETohydrodynamics (MHD) around a $10^8M_{\odot}$ BLACK HOLE. This disk is MAGNETic pressure dominated, and has surface densities more than two orders of magnitude below the corresponding radiation-pressure-supported $α$-disk prediction. By restarting the simulation with multiple frequency groups, we compute the emergent continuum directly from the frequency-dependent radiation fluxes and find no sharp HI Lyman edge at 13.6 eV. This suppressed Lyman edge is mainly caused by the low densities in a MAGNETic pressure supported disk where the Lyman opacity jump is far weaker than in standard disk models. These results indicate that MAGNETic pressure support may provide a possible solution to reconciling optically thick AGN disks with the smooth observed continuum emission around the Lyman edge. However, in this simulation, a substantial fraction of the emission near 13.6 eV is expected to originate at smaller radii closer to the central BLACK HOLE, which is outside our simulation domain. More detailed predictions of the spectrum will require an extension to the inner disk, non-LTE radiation transfer, higher frequency resolution and a survey across a broader range of accretion rates.
[abstract 14 / 70] Yes (score: 5) - Title: The evolution of protostars powered by DARK MATTER annihilation. I. Fiducial model and first resultsAuthors: Devesh Nandal, Konstantinos Topalakis, Jonathan C. Tan, Vasilisa Sergienko, Anaïs Pauchet, Maya Petkova,Comments: 11 pages, 7 figures, accepted in A&ASubjects: astro-ph.SR astro-ph.GA astro-ph.HECreated: 2026-09-20; Updated: 2026-09-22; Datestamp: 2026-09-22
The existence of billion-solar-mass QUASARs at redshifts $z \gtrsim 7$ poses a formidable challenge to theories of BLACK HOLE formation, requiring pathways for the rapid growth of massive seeds. One such pathway arises from primordial stars powered by DARK MATTER (DM) self-annihilation rather than conventional fusion, which could form massive BLACK HOLE seeds in ordinary cosmological mini-haloes. Here we present a suite of stellar evolution models for DM-powered protostars, computed with the \textsc{GENEC} code. We explored a wide parameter space, spanning ambient WIMP densities of $ρ_χ\sim 10^{12}\mbox{--}10^{16}\,\mathrm{GeV\,cm^{-3}}$ and gas accretion rates of $10^{-3}\mbox{--}10^{-1}\,M_\odot\,\mathrm{yr^{-1}}$, to quantify the effects of DM annihilation. A central finding is that for a protostar to grow to supermassive scales ($\gtrsim 10^5 \, M_{\odot}$), the ambient DM density in the vicinity of the star must exceed a critical threshold of $ρ_χ \gtrsim 5 \times 10^{14} \, \text{GeV cm}^{-3}$. The energy injected by WIMP annihilation inflates the protostar, lowering its surface temperature, which suppresses the ionising feedback that would otherwise halt accretion and delays the onset of hydrogen fusion. In dense halos ($ρ_χ\gtrsim 10^{15}\,\mathrm{GeV\,cm^{-3}}$), stars remain stable against general RELATIVISTIC instability beyond $10^6 \, M_{\odot}$, whereas at lower densities ($ρ_χ\lesssim 10^{13}\,\mathrm{GeV\,cm^{-3}}$), they collapse at masses of $\sim 5 \times 10^5 \, M_{\odot}$. Once the DM fuel is exhausted and core burning commences, the protostar contracts and its ionising photon output can reach high levels $\sim 10^{53}\:{\rm s}^{-1}$. These distinct evolutionary phases offer clear observational signatures for the \textsc{JWST}, providing a robust, physically grounded pathway for forming heavy BLACK HOLE seeds in the early Universe.
[abstract 15 / 70] Yes (score: 5) - Title: A Comprehensive JWST/NIRSpec Census of Broad-line Active Galactic Nuclei: Faint, Low-mass Accretors and a Population of Little Red DotsAuthors: Caroline Baccus, Xinfeng Xu,Comments: Submitted to the Astrophysical Journal, 19 pages, 7 figuresSubjects: astro-ph.GACreated: 2026-09-20; Updated: 2026-09-22; Datestamp: 2026-09-22
We present a sample of 227 broad-line ACTIVE GALACTIC NUCLEi (BLAGNs), incorporating 148 newly identified sources, spanning a redshift interval from z = 0.8 to 7.2. We analyze spectroscopic data from the NIRSpec instrument on board the James Webb Space Telescope, using the G140H, G140M, G235H, G235M, G395H, and G395M gratings to survey N ~ 80,000 galaxies for BLAGNs. Through emission-line fitting, using a sum of Gaussian models for $Hα$, $Hβ$, [N II] $λλ$6548, 6584, and [O III] $λλ$4959, 5007, we separate ACTIVE GALACTIC NUCLEus (AGN) broad-line components from narrow-line emission. We find the detection rate of BLAGNs to be relatively consistent across our redshift range. Compared to typical low-z AGNs (z $\lesssim$ 1), high-z BLAGNs are systematically fainter and less massive, yet they accrete more efficiently, with most showing Eddington ratios between 0.1 and 1.0. This confirms rapid BLACK HOLE growth during the early cosmic epochs. The detection of faint, low-mass BLAGNs at high redshift also helps bridge the observational gap between local supermassive BLACK HOLEs and remote luminous QUASARs, providing a more complete view of BLACK HOLE-galaxy coevolution across cosmic time. We also identify 48 known little red dots (LRDs) in our BLAGN sample. For these LRDs, we find a systematic preference for exponential over Gaussian broad-line profiles, which are consistent with electron scattering rather than virial broadening. This implies that standard virial BLACK HOLE masses for LRDs may be overestimated by up to 2 orders of magnitude.
[abstract 16 / 70] Yes (score: 5) - Title: Identifying potentially missed extended sources in the FERMI-LAT 4FGL Catalog using clustering analysisAuthors: Giovanni Cozzolongo, Alison M. W. Mitchell, Samuel T. Spencer, Dmitry V. Malyshev, Tim Unbehaun,Comments: Published in Astronomy & AstrophysicsSubjects: astro-ph.HECreated: 2026-09-21; Updated: 2026-09-22; Datestamp: 2026-09-22
Many FERMI Large Area Telescope (LAT) sources remain unassociated. Some may be extended sources represented by multiple catalog entries, as found for HESS J1813-178. We search for clusters of unassociated FERMI-LAT sources and test whether single extended-source models describe them better than multiple catalog sources. We applied DBSCAN to 4FGL sources with a linking scale of $0.3^\circ$ over 5 GeV-1 TeV. Each cluster contains at least one unassociated source and up to one extended or point-like associated source from selected categories, including pulsars, pulsar wind nebulae and SUPERNOVA remnants. Using FERMIpy, we compared extended- and multiple-source models and characterized each candidate spectrally and morphologically, focusing on the Galactic plane. We identified 48 clusters containing 124 sources, each with at least one unassociated source. For all 8 clusters passing our quality selection, an extended-source model is statistically preferred. At linking scales of $0.4^\circ$ and $0.5^\circ$, all 8 clusters retain their core sources. Cross-matches with the Second FERMI Galactic Extended Sources Catalog (2FGES) and the HESS Galactic Plane Survey (HGPS) showed that 5 clusters overlap known extended sources. The other 3 clusters, including one cluster with a morphology dependent on the interstellar emission model, have no counterpart in either catalog and are new extended-source candidates. Spatial clustering combined with likelihood-based model comparison can uncover extended sources missed in the FERMI-LAT catalog and complements existing searches.
[abstract 17 / 70] Yes (score: 5) - Title: Galaxy-SMBH co-evolution in 2,435 DESI disk galaxies and merger-free BH growth in bulgeless disksAuthors: Sophie M. Jewell, Rebecca J. Smethurst, Chris J. Lintott, Brooke D. Simmons, Ricarda S. Beckmann, Izzy L. Garland, Tobias Géron, Benne W. Holwerda, Karen L. Masters, Ragadeepika Pucha, Ashley Spindler,Comments: 23 pages, 11 figures, Accepted to MNRASSubjects: astro-ph.GA astro-ph.HECreated: 2026-09-18; Updated: 2026-09-22; Datestamp: 2026-09-22
We analyse BLACK HOLE scaling relations for disk-dominated galaxies, and present evidence for secularly driven galaxy-BLACK HOLE co-evolution. We do this observationally by looking at ``bulgeless'' galaxies, where the lack of a stellar bulge suggests a quiet merger history. We first compose a sample of 2,435 disk-dominated galaxies hosting optical broad line ACTIVE GALACTIC NUCLEi (AGN) from DESI data, and find a $M_{\mathrm{BH}}$--$M_{*}$ scaling relation of $\log(M_{\mathrm{BH}})= - 3.7^{+0.3}_{-0.3} + 1.00^{+0.03}_{-0.03} \log(M_*)$. From these, we identify 546 bulgeless galaxies hosting AGN, a factor of $\gtrsim 5$ larger than pre-existing samples, and find they follow the same $M_{\mathrm{BH}}$--$M_{*}$ relation as the general disk galaxy sample. Comparing the bulgeless galaxies to those with some bulge component, we find good agreement in the $M_{\mathrm{BH}}$--$M_{*}$ relation (within $3 σ$), but disagreement in the $M_{\mathrm{BH}}$--$M_{*, \mathrm{bulge}}$ relation (at $>7 σ$). This is the opposite of what is expected from merger-driven co-evolution, suggesting secular growth is significant in establishing observed $M_{\mathrm{BH}}$--$M_{*}$ scaling relations. Furthermore, in a control sample of early-type galaxies we find tentative evidence of increased AGN luminosity compared to the bulgeless sample, but no statistical difference in BLACK HOLE mass. This suggests the assumed merger-dominated evolutionary history of early-type galaxies does not lead to significantly increased long-term BH growth. These results support numerous recent observational and theoretical studies which suggest secular processes fuel significant supermassive BLACK HOLE growth and galaxy-BLACK HOLE co-evolution.
[abstract 18 / 70] Yes (score: 5) - Title: Stereoscopic gravitational-wave probe: Gravitational lensing of a binary merger in ACTIVE GALACTIC NUCLEiAuthors: Paul Martens, Samson H. W. Leong, Ryan Zhang, Otto A. Hannuksela,Comments: 23 pages, 8 figuresSubjects: astro-ph.HE gr-qcCreated: 2026-09-19; Updated: 2026-09-22; Datestamp: 2026-09-22
Recent work has shown that, if a large fraction of the LIGO-Virgo-KAGRA compact binary coalescences (CBCs) occur in accretion disks around ACTIVE GALACTIC NUCLEi (AGNs), many such AGN-CBC systems will likely experience lensing and produce multiple gravitational-wave (GW) "images" of the CBCs that will become detectable with current or future GW detectors. However, the waveforms produced by such lensed "images" will differ from those produced by other lensing systems because the binary source is orbiting the AGN's central supermassive BLACK HOLE at a close distance. Here, we show that these systems produce 2 snapshots of the same binary source from 2 different viewing angles. These differences in the effective viewing angle between the images are encoded in the GWs they emit, such that GW detectors can effectively analyse the waveforms from 2 viewpoints. Beyond such "multi-view lensing", the GW images may also differ by their Doppler shift due to the expected RELATIVISTIC orbital motion of the source around the AGN, an effect which is further amplified by the proximity to the lens. If the AGN's own angular momentum can be related to the binary's orbital angular momentum, we can describe the entire AGN-CBC system using only one additional free parameter compared with a typical point-mass lens system, or with 3 additional parameters when we do not make such an assumption. In this work, we establish a framework of transformation rules that describe both the angles in the 2 points of view, and the Doppler effect that comes from the source's motion around the lens. We also provide the framework to produce consistent AGN-lensed waveforms from any currently available GW waveform. These AGN-CBC systems give 2 unique points of view on a binary merger thus opening up a new window into the merger's properties unlike any other lens system.
[abstract 19 / 70] Yes (score: 4) - Title: Mrk 382: A Narrow-line Seyfert 1 Galaxy with Recurrent X-ray State TransitionsAuthors: Yanli Ai, Wenfeng Wen, Liming Dou, Jiahua Wu, Chen Hu, Tinggui Wang, Xiaohui Yang, Jing Wang, Xue-Bing Wu, Qiusheng Gu, Xinwen Shu, Pudu, Jian-Min Wang,Comments: ApJ, acceptedSubjects: astro-ph.HE astro-ph.GACreated: 2026-09-20; Updated: 2026-09-22; Datestamp: 2026-09-22
We report recurrent X-ray state transitions in the nearby narrow-line Seyfert~1 galaxy Mrk~382 using multi-epoch observations from \textit{SWIFT}, \textit{Chandra}, \textit{XMM-Newton}, and eROSITA, together with archival ultraviolet, optical, and infrared data. The 0.3--2 keV flux varies by nearly an order of magnitude over the past $\sim15$ yr, with multiple transitions between bright and faint states. The source brightened by a factor of $\sim10$ between the 2010 \textit{Chandra} observation and the 2011 \textit{XMM-Newton} high state, then declined by $\sim6$--7 to a low state in 2019, followed by renewed brightening in recent \textit{SWIFT} monitoring. The X-ray spectrum shows strong state-dependent evolution, changing from a steep high-state continuum ($Γ=2.32\pm0.04$) to a much harder low-state spectrum ($Γ=1.39\pm0.06$). The low-state spectrum also exhibits a narrow Fe K$α$ line with an equivalent width of $\sim330$ eV. Reflection modeling indicates that the low-flux state is strongly reflection dominated, with the reflection fraction increasing from $R_{\rm refl}\sim4$ to $\sim34$, consistent with a compact corona subject to strong light-bending effects. The ultraviolet emission broadly follows the long-term X-ray variability but with smaller amplitude, while the optical and mid-infrared bands vary more mildly. Despite the dramatic X-ray variability, Mrk~382 does not enter an extreme X-ray-weak state, and we did not detect clear optical spectral-type changes based on the currently available observations. Mrk~382 is therefore a rare nearby Seyfert galaxy undergoing recurrent X-ray state transitions, providing a valuable laboratory for studying changing coronal geometry and multiwavelength AGN variability.
[abstract 20 / 70] Yes (score: 4) - Title: Multi-tracer constraints on QUASAR outflows. Acceleration from BLR to galactic scalesAuthors: M. Brazzini, M. Bischetti, S. Hagen, V. D'Odorico, N. Arav, G. Becker, G. Cupani, F. Fiore, M. Ghosh, E. Piconcelli, F. Salvestrini, M. Sharma, A. Travascio, A. Tortosa, G. Vietri, L. Zappacosta, C. Feruglio,Comments: 10 pages, 7 figures. Submitted to A&ASubjects: astro-ph.GACreated: 2026-09-18; Updated: 2026-09-22; Datestamp: 2026-09-22
Black hole-driven outflows are a fundamental component of the Active Galactic Nuclei (AGN) paradigm, and may play a major role in regulating the evolution of both supermassive BLACK HOLEs and their host galaxies. Yet, their physical properties remain challenging to constrain, due to their multi-phase and multi-scale nature which demands a combined approach of different complementary observational tracers. In this work, we investigate AGN-driven ionized outflows from nuclear to galaxy scale within individual QUASARs, with the aim of establishing whether and how these phenomena are physically connected. We assemble a luminosity-matched sample of 148 QUASARs with bolometric luminosities higher than 10^47 erg/s, spanning the redshift range z~2-6.5. We perform a homogeneous analysis of CIV emission and broad absorption line (BAL) profiles to derive outflow properties on different spatial scales. We find statistically significant correlations between emission- and absorption-based outflow diagnostics, including the minimum and maximum BAL velocities, vmin,BAL and vmax,BAL, and the v98 of CIV emission lines. These correlations are tighter in high redshift QUASARs. We also find evidence for an evolution of outflow properties across cosmic time, with high-redshift QUASARs exhibiting systematically larger CIV line shifts and broader profiles, and faster BAL outflows. According to our outflow toy model, these correlations suggest a scenario in which a clumpy BAL wind is composed of expelled and accelerated broad-line region gas clouds.
[abstract 21 / 70] (score: 3) - Title: Absorption effects in the expanding Universe: spectral transmittance functions of the intergalactic medium for distant sourcesAuthors: Anguohao Yang, Bohdan Novosyadlyj, Bohdan Melekh, Gennadii Milinevsky,Comments: 17 pages, 14 figures, 6 tablesSubjects: astro-ph.COCreated: 2026-09-21; Updated: 2026-09-22; Datestamp: 2026-09-22
We construct two self-consistent analytic approximations to the neutral hydrogen fraction, $x_{\rm HI}(z)$, and the helium ionization fractions, $x_{\rm HeI}(z)$, $x_{\rm HeII}(z)$, and $x_{\rm HeIII}(z)$, that are consistent with current constraints inferred from QUASAR spectra, galaxy surveys, and CMB POLARIZATION measurements. These approximations describe observationally motivated early- and late-reionization scenarios. Using these histories, we analyse the formation of broad absorption troughs in the continuum spectra of high-redshift sources over $1\leq z_{\rm s}\leq15$. We assume that neutral hydrogen and helium in a homogeneous diffuse intergalactic medium reside predominantly in their ground states and absorb radiation through the Lyman-series lines and continua of HI, HeI, and HeII. We compute the wavelength-dependent optical depths for the first 39 Lyman-series lines of HI and HeII, the first 10 lines of HeI, and the corresponding continua, and use them to derive spectral transmittance functions, $T(λ;z_{\rm s})$. As illustrative applications, we apply them to toy-model continuum spectra of starless haloes and to model spectra of a low-metallicity dwarf galaxy at different redshifts. Spectral features in sources at $5\lesssim z_{\rm s}\lesssim7$ caused by intergalactic absorption are found to be particularly sensitive to the adopted hydrogen and helium ionization histories
[abstract 22 / 70] (score: 3) - Title: Testing the strong equivalence principle with multimessenger binary neutron star mergersAuthors: Jie Zhu, Hanlin Song, Zhenwei Lyu, Hao Li, Peixiang Ji, Jun-Chen Wang, Haobo Yan, Bo-Qiang Ma,Comments: Accepted version for Communication PhysicsSubjects: gr-qcCreated: 2026-09-19; Updated: 2026-09-22; Datestamp: 2026-09-22
The constancy of the gravitational constant $G$ is a cornerstone of the strong equivalence principle and of general relativity, yet its possible temporal variation remains a key target in tests of fundamental physics. Gravitational-wave (GW) astronomy, especially when combined with electroMAGNETic observations, provides an unprecedented new opportunity to probe this principle in the strong-field and dynamical regime. In this work, we develop a GW waveform model with a slowly varying gravitational constant, incorporating its effects both on compact binary dynamics and GW propagation in an expanding universe. Applying this framework to the binary neutron star merger GW170817, together with independent electroMAGNETic constraints on the luminosity distance, sky localization and binary inclination from GRB 170817A, we perform a joint Bayesian analysis that disentangles varying-$G$ effects from astrophysical degeneracies. We find no evidence for a temporal variation of the gravitational constant, and constrain its fractional time derivative to $\dot{G}/G \in [-3.36 \times 10^{-9}, 5.34\times10^{-10}]~{\rm yr^{-1}}$, representing the most stringent bounds obtained to date from real GW observations. Our results demonstrate the power of multi-messenger astronomy as a precision probe of the strong equivalence principle in the RELATIVISTIC regime.
[abstract 23 / 70] (score: 3) - Title: Multi-wavelength Emission Modeling from Accretion Flows around Isolated Black Holes Including Magnetic Flux TransportAuthors: Takumi Koshimizu, Shigeo S. Kimura,Comments: 17 pages, 12 figures. Published in The Astrophysical JournalSubjects: astro-ph.HECreated: 2026-09-19; Updated: 2026-09-22; Datestamp: 2026-09-22
Isolated stellar-mass BLACK HOLEs (IBHs) are expected to be abundant in the Milky Way, yet their electroMAGNETic signatures remain largely undetected. We investigate the detectability of IBHs in molecular clouds using a 1D, multi-wavelength emission model that incorporates MAGNETic flux transport controlled by the MAGNETic Prandtl number $P_m$. We find that MAGNETically arrested disks (MADs) form for $P_m\gtrsim 1$, where the MAGNETic flux threading the BLACK HOLE is in a saturation value. On the other hand, MAD formation is restricted to a limited parameter range for $P_m<1$, In our model, outer parts of accretion disks, around 100 gravitational radii, efficiently emit infrared photons detectable by WISE. This feature is not captured by the conventional one-zone model. X-ray emission depends strongly on $P_m$; For $P_m=1$ where MAD is formed, X-ray emission is dominated by nonthermal radiation, whereas inverse Compton emission becomes dominant for $P_m=0.5$ where the MAGNETic field is weaker than the saturation value. X-ray detection is plausible if they are in dense molecular-cloud filaments for $P_m\ge1$, although it is challenging for $P_m< 1$. These results demonstrate that MAGNETic flux transport plays a key role in shaping the multiwavelength observational signatures of IBHs.
[abstract 24 / 70] (score: 3) - Title: Effect of Neutron Star Jets on Common Envelope EvolutionAuthors: Deepanshu Gurjar, Luke Chamandy, Eric G. Blackman, Yangyuxin Zou, Baowei Liu, Jason Nordhaus,Comments: 13 pages, 9 figures, 1 table, ApJ, in pressSubjects: astro-ph.SR astro-ph.HECreated: 2026-09-20; Updated: 2026-09-22; Datestamp: 2026-09-22
The common envelope (CE) phase is a key stage in binary star evolution that is still not very well understood. Once engulfed by the giant star, the binary companion may accrete envelope material. For neutron star (NS) companions, such accretion may in principle occur at mass rates several orders of magnitude above the Eddington limit and may result in outflows dominated by powerful bi-polar JETs with mass-loss rates similar to the accretion rates. Such JETs would impact the morphology of the system and the rate of envelope unbinding, which affect the duration and outcome of the CE event. Employing 3D global hydrodynamic simulations, we study the role of such NS JETs in a CE event involving a red giant branch star. The JETs eventually drill through and break out of the envelope, producing prominent low-density bi-polar lobes. The JETs cause about twice as much envelope mass to be unbound ($\sim20\%$ of the envelope) as compared to simulations of the same duration without NS JETs ($\sim10\%$). However, the rate of mass unbinding due to the JETs decreases towards the ends of the simulations as the JETs break out and energetically decouple from the envelope. Moreover, JET activity leads to slightly reduced drag on the binary, decreasing the rate of orbital energy transfer to the envelope. Hence, while such powerful JETs can play an important role, negative feedback effects tend to prevent them from dominating envelope unbinding and dictating CE outcomes.
[abstract 25 / 70] (score: 3) - Title: Nonlinear Tearing Modes in Current-Vortex SheetsAuthors: D. Urbanski, F. L. Waelbroeck, A. Tenerani,Comments:Subjects: physics.plasm-phCreated: 2026-09-19; Updated: 2026-09-22; Datestamp: 2026-09-22
The linear and nonlinear development of instabilities and Alfvén resonances in a plane current-vortex sheet is presented here for sheared equilibrium profiles $\boldsymbol{B_{y0}} = \tanh(z)\boldsymbol{\hat{y}}$ and $\boldsymbol{V_{y0}} = M_0\tanh(z/r)\boldsymbol{\hat{y}}$. We extend Rutherford's nonlinear model for constant-psi MAGNETic islands to account for a sheared equilibrium flow and determine the flow's impact on the MAGNETic island's nonlinear evolution for $M_0<1$. In this regime, the flow introduces two nonlinear contributions: a POLARIZATION current term and a modification of the saturation term derived by Militello and Porcelli (2004). We find that the POLARIZATION current generated by the equilibrium flow consistently reduces the nonlinear growth rate of the tearing mode. The flow-induced modification of the saturation term, however, depends on the MAGNETic-to-velocity shear width ratio, $r$. For $r=1$, the saturation term is unchanged from the case without flow. For $r>1$, it increases in magnitude with $M_0$, strengthening its stabilizing effect and further reducing the island growth rate. In contrast, for $r<1$, the saturation term decreases in magnitude with increasing $M_0$ and can become positive, leading to a transition from a stabilizing to a destabilizing contribution. Nevertheless, throughout the parameter range considered, the combined effect of the POLARIZATION current and modified saturation term is to slow the growth of the MAGNETic island. Finally, we find that, in the presence of Alfvén resonances, the MAGNETic island's growth in the nonlinear regime is no longer adequately characterized by constant-psi, and the dynamics of such islands are not captured by the model.
[abstract 26 / 70] (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: 2026-09-21; Updated: 2026-09-22; Datestamp: 2026-09-22
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 27 / 70] (score: 3) - Title: Low-power JET-ISM coupling and disk-plane perturbations in the edge-on Seyfert galaxy NGC 4388Authors: M. Ceci, G. Venturi, C. Marconcini, M. V. Zanchettin, G. Cresci, M. Tartėnas, K. Zubovas, E. Treister, E. Amenta, E. Bertola, F. Belfiore, C. Bracci, E. Cataldi, Q. D'Amato, A. Feltre, M. Ginolfi, I. Lamperti, F. Mannucci, A. Marconi, A. Marasco, M. Meenakshi, M. Mingozzi, B. Moreschini, D. Mukherjee, E. Nardini, M. Perna, F. Ricci, M. Scialpi, L. Ulivi,Comments: Submitted to A&A; 15 pages (plus 7 pages of supplementary material), 7 figures (plus 5 in the appendix); Abstract adapted from originalSubjects: astro-ph.GACreated: 2026-09-18; Updated: 2026-09-22; Datestamp: 2026-09-22
Active galactic nuclei (AGN) may regulate galaxy evolution through radiatively driven winds and collimated JETs, but their relative impact and coupling to the interstellar medium (ISM) remain uncertain. We investigate the ionized gas in the nearby ($D\sim$ 17 Mpc) Seyfert 2 galaxy NGC 4388, hosting a galaxy-scale ($\sim$1.6 kpc), low-power ($\sim1.4~\times~10^{42}~erg~s^{-1}$) bipolar radio JET projected roughly perpendicular to its edge-on disk. We analyze optical integral-field spectroscopic observations from the Wide Field Mode with adaptive optics of VLT/MUSE, complemented by VLA radio data tracing the JET. We map ionized-gas emission, kinematics, excitation, and dust attenuation. We reconstruct the de-projected 3D outflow geometry and velocity field using the MOKA3D kinematic model, and estimate its mass and energetics. The ionized gas shows a rotating disk and a kpc-scale biconical outflow. We measure a total ionized outflow mass of $\sim10^6~M_\odot$, a mass outflow rate of $\sim0.2~M_\odot$~yr$^{-1}$, and a kinetic power of $\sim3\times10^{40}~erg~s^{-1}$, which gives a coupling efficiency of $\sim1\%$ relative to both the JET kinetic and the radiation-driven nuclear wind power, indicating that either mechanism could drive the outflow. We detect an extended ($\sim$2 kpc) enhancement of the gas velocity dispersion along the galaxy disk plane, oriented perpendicular to the outflow and JET axes. These regions show optical line ratios consistent with shock excitation. The spatial correspondence with ALMA CO(2-1) emission is marginal, while enhanced stellar velocity dispersion prevents an exclusive JET interpretation. We report the first observational evidence that even a low-power radio JET oriented nearly perpendicular to the galaxy disk can efficiently couple with the ISM, suggesting that JET-induced perturbations are an important AGN feedback channel regardless of JET orientation.
[abstract 28 / 70] (score: 3) - Title: Importance of the Resonant Cosmic-Ray Streaming Instability Upstream of Collisionless ShocksAuthors: Bricker Ostler, Benedikt Schroer, Damiano Caprioli,Comments:Subjects: astro-ph.HECreated: 2026-09-18; Updated: 2026-09-22; Datestamp: 2026-09-22
Cosmic rays (CRs) escaping collisionless shocks form a dilute, RELATIVISTIC population whose current amplifies the upstream MAGNETic field, a process widely attributed to the non-resonant (Bell) instability. Solving the dispersion relation for both cold and finite-spread CR distributions, we show that for the maximum-energy escaping population, the resonant mode can outgrow the non-resonant mode. At slower shocks, this dominance persists for broader CR distributions, and sufficient pitch-angle broadening can even stabilize the non-resonant mode while leaving the resonant mode unstable. Relativistic hybrid particle-in-cell simulations confirm the cold-beam linear theory predictions and, in the nonlinear regime, saturate at $δB/B_0 \sim 1$ with significant pitch-angle redistribution. Neglecting the resonant instability thus underestimates MAGNETic field growth at the very scale needed to confine the highest-energy escaping CRs.
[abstract 29 / 70] (score: 3) - Title: Hard X-Ray Quasi-Periodic Pulsations in X-Class Solar Flares Observed by Aditya-L1/HEL1OSAuthors: Sachin Rajkapoor Kanaujiya, Ram Ajor Maurya, Swetha Gopinathan, Valery M. Nakariakov,Comments: 17 pages, 5 figures, 2 tables, Accepted for Publication in The Astrophysical Journal (ApJ)Subjects: astro-ph.SRCreated: 2026-09-19; Updated: 2026-09-22; Datestamp: 2026-09-22
We present the catalogue of quasi-periodic pulsations (QPPs) detected in hard X-ray (HXR) observations of X-class solar flares obtained with the HEL1OS instrument onboard Aditya-L1 during July 2024 - March 2026. The catalogue comprises 34 flares spanning GOES classes X1.1 - X7.1. QPPs are detected and studied using a uniform procedure based on Ensemble Empirical Mode Decomposition (EEMD) and wavelet analyses. Statistically significant QPPs are identified in 25 events (~74%), demonstrating that QPPs are a common property of X-class flares. The detected periods range from approximately 1 to 3 min, with a pronounced concentration between 1.3 and 1.7 min, suggesting the existence of a preferential timescale that may be associated with kink or slow MAGNETohydrodynamic oscillations in the flaring region. The dominant periods remain nearly independent of photon energy across the 8 - 20 keV range, while the modulation depth increases systematically with photon energy following a power-law relation with an exponent of about 1.5. QPPs detected in different HXR energy channels exhibit strong phase coherence and positive cross-correlation coefficients, indicating modulation by a common physical mechanism. Several intense flares display HXR modulation depths of up to 25%, providing evidence for nonlinear effects. The observed statistical properties support models in which QPPs are generated by repetitive MAGNETic RECONNECTion, either spontaneous or periodically modulated by MAGNETohydrodynamic oscillations. This study establishes HEL1OS as a powerful instrument for quantitative studies of flare QPPs during Solar Cycle 25.
[abstract 30 / 70] (score: 3) - Title: The interplay between AGN photo-ionization, radio JET, and STAR FORMATION in the z $\sim$ 3.5 RADIO GALAXy 4C +03.24Authors: Bruno Dall'Agnol de Oliveira, Dominika Wylezalek, Pranav Kukreti, Wuji Wang, Rogério Riffel, Rogemar A. Riffel, Andrey Vayner, Caroline Bertemes, Julian T. Groth, David S. N. Rupke, Carlos De Breuck, Joël Vernet,Comments:Subjects: astro-ph.GACreated: 2026-09-19; Updated: 2026-09-22; Datestamp: 2026-09-22
High-redshift RADIO GALAXies (HzRGs) are among the most powerful radio sources, and are associated with the most massive galaxies and dense environments at redshifts z $\gtrsim$ 1. They are ideal laboratories for studying how Active Galactic Nuclei (AGN) events can shape the evolution of galaxies, as intense radiation, JETs, and STAR FORMATION are simultaneously observed. We present JWST/NIRSpec integral-field spectroscopy ($\sim$ 1.6 kpc spatial resolution) of the 4C +03.24 system, a powerful HzRG at z $\sim$ 3.5 with a bolometric luminosity of $\sim 10^{47.6}$ erg s$^{-1}$. We identify kinematically disturbed regions in the warm ($\sim 10^4$ K) ionized gas by decomposing the emission-line spectra into multiple Gaussian components, which is crucial to avoid overestimating the outflow properties. The outflow power peaks at $\sim$ 2 kpc away from the nucleus, with a corresponding low kinetic coupling efficiency of $\sim 8_{-5}^{+7} \times 10^{-3}$ %. A combined analysis of the rest-frame optical and UV (from VLT/MUSE and HST imaging) continua reveals an extended emission (spanning $\sim$ 14 kpc), which we interpret as partially tracing star-forming regions. With a clearly delineated bipolar morphology, we show that the AGN photo-ionization dominates the ionization of the interstellar medium (ISM) along the radio JET axis. The [C II]$λ$158$μ$m emission gap in this region might be direct evidence of negative AGN feedback. We also discuss a possible scenario where 4C +03.24 could be situated in an overdense environment experiencing multiple galaxy interactions, and the possibility of JET-induced star-formation.
[abstract 31 / 70] (score: 3) - Title: Charged particles and QPO constraints in tidal charge BLACK HOLE MAGNETosphere sourced by a current loopAuthors: Ozodbek Abdurakhmonov, Javlon Rayimbaev, Inomjon Ibragimov, Sherzod Djumanov, Nuraliev Farhod, lkhomjon Makhmudov,Comments: 17 pages,32 figuresSubjects: gr-qc astro-ph.HECreated: 2026-09-19; Updated: 2026-09-22; Datestamp: 2026-09-22
We investigate the dynamics of charged particles in the dipolar electroMAGNETic field generated by a stationary current loop around a static BLACK HOLE in the Randall--Sundrum braneworld model. The current loop is located at the innermost stable circular orbit (ISCO) of the tidal charged BLACK HOLE, and the azimuthal electroMAGNETic four-potential is obtained as an exact analytical solution of the Maxwell equations in the curved background. Starting from the Hamilton--Jacobi equation, we derive the effective potential for charged particle motion in both the interior and exterior regions of the current loop, and analyze the dependence of the ISCO radius, angular momentum, energy, and orbital frequency on the tidal charge parameter $b$ and the MAGNETic coupling parameter $ω$. We further compute three fundamental frequencies and show that the dipolar loop field revives a nonzero nodal precession frequency even though the background is static and non-rotating. Using these frequencies we construct five twin-peak QPO models (RP, WD, and ER2--ER4) and perform a Markov chain Monte Carlo (MCMC) analysis to constrain the braneworld parameters $(b,ω)$ from the observed twin-peak QPO frequencies of six BLACK HOLE sources spanning three mass regimes: GRO~J1655--40, XTE~J1550--564, GRS~1915$+$105, H~1743$+$322, M82~X-1, and Sgr~A$^{*}$. Adopting the epicyclic-resonance ER4 model as the representative framework, we find moderate, non-negligible tidal charges $b\simeq0.3$--$1.0$, while the MAGNETic coupling remains consistent with zero, $|ω|\lesssim0.05$. Our results therefore place upper bounds on the tidal charge and on the MAGNETic coupling strength from astrophysical QPO data.
[abstract 32 / 70] (score: 3) - Title: Stellar flare detection and characterization in ZTF High-cadence light curvesAuthors: Aratrika Ghosh, Shravan Hanasoge, Matthew J. Graham, Ashish Mahabal,Comments: 18 pages, 13 figures, 7 tables. Accepted for publication in ApJSubjects: astro-ph.SRCreated: 2026-09-21; Updated: 2026-09-22; Datestamp: 2026-09-22
Stellar flares are brief, intense increases in brightness resulting from MAGNETic RECONNECTion events in stellar atmospheres. In this paper, we have developed a pipeline to detect and characterize flares in short-duration (approximately 6.2-hour) light curves from the Zwicky Transient Facility (ZTF) Extended Deep-Drilling survey. This method involves robust detrending with Tukey's biweight estimator, followed by sigma-based thresholding and visual scrutiny to identify flare candidates. It is applied to 28 million light curves, and we found 331 flaring events from 310 stars across evolutionary stages and spectral types. We estimated flare energies by assuming a blackbody emission model for 234 flares with reliable distance, and flare morphologies were classified based on flare modeling using the template by Mendoza et al.(2022). We obtained a power law correlation between energy and duration with an index of $0.19 \pm 0.01$. We also find similar power law correlation between the flare energy and $T_{decay}$, $T_{rise}$ and FWHM. This study demonstrates the power of high-cadence ground-based surveys for statistical and morphological flare studies across a broad stellar sample.
[abstract 33 / 70] (score: 3) - Title: The Role of Non-local Thermal Transport in Flare-Driven Chromospheric EvaporationAuthors: Thomas Parmenter, Tony Arber, Sergey Belov, Tom Goffrey,Comments: 17 pages including references, 11 figuresSubjects: astro-ph.SRCreated: 2026-09-21; Updated: 2026-09-22; Datestamp: 2026-09-22
Thermal conduction plays an important role in energy transport during solar flares. Flares heat the solar atmosphere to tens of MK which, combined with mean free paths in excess of 1Mm, can cause the heat flux to become non-local. We use the MAGNETohydrodynamic Lare2d code to simulate a RECONNECTive heating event with three different thermal conduction models: classical Spitzer-Harm (SH) along the MAGNETic field, local transport with a heat flux limiter (FL), and the non-local Schurtz, Nicolai, Busquet (SNB) model which is routinely used in LASER-plasma codes and has been bench- marked against full Vlasov-Fokker-Planck treatment. The evolution of the atmosphere post heating is compared between simulations using each of these models. Due to a supressed heat flux, SNB gives rise to significantly higher peak temperatures than SH. Further, with SNB transport chromospheric evaporation occurs later and has stronger extreme ultraviolet emission intensity. FL simulations have similar temperature evolution and chromospheric evaporation to SNB, however different values of the flux limiter work best for peak temperature, downflow velocity and EUV emission intensity, and so there is no one optimal value for all cases. We conclude that the SNB model provides a practicable solution to incorporate non-local thermal transport at MHD scales, which will be crucial to improve the realism and accuracy of the next generation of solar flare simulations.
[abstract 34 / 70] (score: 2) - Title: A lanthanide-rich kilonova in the aftermath of a long GAMMA-RAY BURSTAuthors: Yu-Han Yang, Eleonora Troja, Brendan O'Connor, Chris L. Fryer, Myungshin Im, Joe Durbak, Gregory S. H. Paek, Roberto Ricci, Clécio R. De Bom, James H. Gillanders, Alberto J. Castro-Tirado, Zong-Kai Peng, Simone Dichiara, Geoffrey Ryan, Hendrik van Eerten, Zi-Gao Dai, Seo-Won Chang, Hyeonho Choi, Kishalay De, Youdong Hu, Charles D. Kilpatrick, Alexander Kutyrev, Mankeun Jeong, Chung-Uk Lee, Martin Makler, Felipe Navarete, Ignacio Pérez-García,Comments: Accepted version; published in Nature 626, 742 (2024)Subjects: astro-ph.HECreated: 2026-09-19; Updated: 2026-09-22; Datestamp: 2026-09-22
Observationally, Kilonovae are astrophysical transients powered by the radioactive decay of nuclei heavier than iron, synthesized in the merger of two compact objects. Over the first few days, the kilonova evolution is dominated by a large number of radioactive isotopes contributing to the heating rate. On timescales of weeks to months, its behavior is predicted to differ depending on the ejecta composition and merger remnant. Previous work has shown that the kilonova associated with GAMMA-RAY BURST 230307A is similar to kilonova AT2017gfo, and mid-infrared spectra revealed an emission line at 2.15 micrometres that was attributed to tellurium. Here we report a multi-wavelength analysis, including publicly available James Webb Space Telescope data and our own Hubble Space Telescope data, for the same GAMMA-RAY BURST. We model its evolution up to two months after the burst and show that, at these late times, the recession of the photospheric radius and the rapidly-decaying bolometric luminosity ($L_{\rm bol}\propto t^{-2.7\pm 0.4}$) support the recombination of lanthanide-rich ejecta as they cool.
[abstract 35 / 70] (score: 2) - Title: Optimal Symmetries in Binary ClassificationAuthors: Vishal S. Ngairangbam, Michael Spannowsky,Comments: added experiments on Jet tagging for optimal and non-optimal symmetriesSubjects: cs.LG cs.AI physics.data-an stat.MLCreated: 2026-09-21; Updated: 2026-09-22; Datestamp: 2026-09-22
We develop a theoretical foundation for designing group-equivariant neural networks that align the choice of symmetries with the underlying probability distributions of the data. Utilising the general structure of fibre decompositions on the domain under group equivariant maps and its relation to that of the likelihood ratio, we present a theoretical framework for identifying group actions that maintain optimal classification performance via the Neyman-Pearson lemma. This provides a unified methodology for improving classification accuracy especially in fundamental applications where one has knowledge of the inherent symmetries of the distributions and how they are broken by measurement. As an application to JET classification at the Large Hadron Collider, we find that there can be performance gains when one utilises smaller permutation symmetries within the constituents. This work offers insights and practical guidelines for constructing more effective group equivariant architectures in diverse machine-learning contexts.
[abstract 36 / 70] (score: 2) - Title: The mechanism for creating "dynamical gravastar" BLACK HOLE mimickers also explains formation of "little red dots"Authors: Stephen L. Adler,Comments: Latex, 10 pages, 2 figures, revised for publicationSubjects: gr-qcCreated: 2026-09-20; Updated: 2026-09-22; Datestamp: 2026-09-22
We argue that a high pressure phase transition of RELATIVISTIC matter to a state with negative energy density, which leads to the formation of horizonless, globally unitary BLACK HOLE mimickers, also gives rise to the appearance of ``little red dots''. The energy source for the dots is the release of latent energy from the phase transition, and their excess redness is a result of this release taking place in a central region of exponentially small positive $g_{00}$, and hence very high gravitational redshift.
[abstract 37 / 70] (score: 2) - Title: Non-Gaussianity in SMICAAuthors: M. Citran, H. V. Tran, G. Patanchon, B. van Tent,Comments: 35 pages, 14 figures. v2: Corrected mistake in and extended analysis of section 6.4 (figure 10), conclusions unchanged v3: Corrected affiliation of one author v4: Version as published on JCAP, added DOI, v5: Added missing acknowledgement to ASIDFSubjects: astro-ph.COCreated: 2026-09-21; Updated: 2026-09-22; Datestamp: 2026-09-22
We develop a new formalism for the component separation method Spectral Matching Independent Component Analysis (SMICA) in order to include the information contained in the foregrounds beyond second-order statistics. We also develop a binned bispectrum estimator that works directly using maps of different frequency channels, capable of determining the bispectrum of multiple components at the same time, shifting the traditional approach to non-Gaussianity estimation from a cleaned map to the component separation step, for a better handling of foreground uncertainty. We test our method on 400 E and B POLARIZATION simulations based on the LiteBIRD experiment, containing the two main sources of contamination for CMB POLARIZATION experiments: polarized dust and SYNCHROTRON emission. We show that the bispectrum does not improve the precision of the power spectrum estimation or of the spectral parameters. However, we are capable of recovering the correct 3-point correlator of the foregrounds and standard constraints on primordial non-Gaussianity in a coherent multi-frequency and multi-component framework. The advantage of our approach is that it combines data in an optimal way accounting for the power spectrum and the bispectrum of the various components, which is not true for the standard approach.
[abstract 38 / 70] (score: 2) - Title: The Composite Spectrum of QSO Absorption Line Systems in DESI DR2Authors: Lucas Napolitano, Adam D. Myers, Adam Tedeschi, Abhijeet Anand, Hiram K. Herrera-Alcantar, Jessica Aguilar, Steven Ahlen, Stephen Bailey, Segev BenZvi, Davide Bianchi, David Brooks, Todd Claybaugh, Andrei Cuceu, Axel de la Macorra, Arjun Dey, Biprateep Dey, Peter Doel, Andreu Font-Ribera, Jaime E. Forero-Romero, Enrique Gaztanaga, Satya Gontcho A Gontcho, Gaston Gutierrez, Julien Guy, Dick Joyce, Anthony Kremin, Martin Landriau, Laurent Le Guillou, Marc Manera, Aaron Meisner, Ramon Miquel, John Moustakas, Seshadri Nadathur, Nathalie Palanque-Delabrouille, Will Percival, Francisco Prada, Ignasi Perez-Rafols, Graziano Rossi, Eusebio Sanchez, David Schlegel, Michael Schubnell, Joesph Harry Silber, David Sprayberry, Gregory Tarle, Benjamin Alan Weaver, Rongpu Zhou, Hu Zou,Comments: 20 pages, 11 figures, 2 tablesSubjects: astro-ph.GACreated: 2026-09-18; Updated: 2026-09-22; Datestamp: 2026-09-22
We present details regarding a composite spectrum of QUASAR (QSO) absorption line systems. In this composite spectrum we identify more than 70 absorption lines, and observe oxygen and hydrogen emission features at a higher signal-to-noise ratio than any previous study. As the light from a distant QUASAR travels towards an observer, it may interact with the circumgalactic medium of an intervening galaxy, forming absorption lines. In order to maximize the signal of these absorption lines, we have selected a sample of 239,174 QUASAR spectra from the second data release of the Dark Energy Spectro- scopic Instrument (DESI), each identified to have absorption lines resulting from such an interaction. By stacking these spectra in the restframe of the absorption, and calculating a median composite spec- trum, we are able to isolate and enhance these absorption lines. We provide a full atlas of all detected absorption and emission lines as well as their fit centroids and equivalent width values. We additionally provide analysis of composites constructed using subsamples of absorbers in both redshift and Mg II equivalent width bins. We find that there is minimal redshift evolution across the considered absorber samples. Additionally, we find that dense gas signatures, such as the presence of Na I absorption, are strongest in the highest equivalent width absorber sample, and that the strengths of the Si IV and C IV absorption lines show a relatively weak correlation with Mg II equivalent width. This atlas should aid in future studies investigating the compositions and physical conditions of these absorbers.
[abstract 39 / 70] (score: 2) - Title: Magnetic field morphological diagnostics with ALMA in the G327.29 protocluster: VGT versus dust POLARIZATIONAuthors: A. Koley, A. M. Stutz, A. Lazarian, Y. Hu, P. Sanhueza, P. Saha, R. H. Alvarez-Gutierrez, N. S. Sandoval-Garrido, N. Castro-Toledo, G. Bernal Mesina,Comments: Minor revision is required before acceptance in Astronomy & Astrophysics (A&A) journalSubjects: astro-ph.GACreated: 2026-09-19; Updated: 2026-09-22; Datestamp: 2026-09-22
Magnetic fields and turbulence may play a key role in the evolution of protoclusters, influencing the formation of dense cores and stars. Here, we examine the morphology of the MAGNETic fields in the G327.29 protocluster using both the velocity gradient technique (VGT) extracted from molecular line emissions and linear POLARIZATION in the dust continuum emission. The VGT analysis is performed using four molecular tracers: DCN (3-2), C18O (2-1), HN13C (3-2), and H13CO+ (3-2) - observed with the ALMA 12 m array. Owing to its sensitivity to gas dynamics, a comparison between VGT and dust POLARIZATION provides a powerful probe of the evolutionary processes in massive star-forming regions. Our analysis reveals a complex MAGNETic-field structure shaped by the combined influence of turbulence and gravity, as evidenced by the distributions of both the alignment measure (AM) and the relative orientation angle (θ_r), between the MAGNETic fields inferred from the VGT and dust POLARIZATION observations. The θ_r distributions are clearly double-peaked for DCN and HN13C, whereas C18O and H13CO+ predominantly exhibit a preferred perpendicular orientation. In addition, it also appears that there is a large-scale (beyond the core scale) gravitational infall from the surrounding medium on to the filament and the central densest region. Furthermore, we observe that cores are dominated by a mix of turbulence and gravity. Overall, this work presents, for the first time, the application of VGT to a massive protocluster, G327.29, using high-resolution ALMA observations.
[abstract 40 / 70] (score: 2) - Title: Small hosts, big appetites: unveiling rapid and early low-mass BLACK HOLE growth in cosmological zoom-in simulations of dwarf galaxiesAuthors: Giulia Ortame, Martin A. Bourne, Sophie Koudmani, Debora Sijacki, Francesco D'Eugenio, Roberto Maiolino,Comments: 27 pages, 12 figures (including 4 appendices)Subjects: astro-ph.GACreated: 2026-09-21; Updated: 2026-09-22; Datestamp: 2026-09-22
Dwarf galaxies are ideal laboratories to probe the interplay between galaxy formation and the growth of BLACK HOLEs (BHs) in the early Universe. Mounting observational evidence reveals the presence of BHs in low-mass galaxies across cosmic time, with $\textit{JWST}$ uncovering a likely population of $\textit{overmassive}$ BHs at $2 \lesssim z \lesssim 11$. Simulations struggle to reproduce this high-redshift regime, motivating revisions to models of BH accretion and feedback from ACTIVE GALACTIC NUCLEi (AGN). To address this, we present high-resolution cosmological zoom-in simulations of a dwarf galaxy based on FABLE physics, introducing novel sink-based BH accretion models and relaxing the fiducial assumption of strong SUPERNOVA feedback. BHs accrete more efficiently in the sink-based runs compared to the `traditional' Bondi-based counterparts, with AGN feedback leading to early, rapid quenching maintained by fast, hot and metal-enriched outflows. These outflows pollute the outer circumgalactic medium, yielding flat metallicity gradients down to $z=0$. We further assess the performance of two widely used virial estimators and find significant departures from the true dynamical mass, especially during the high-redshift dwarf assembly. Since our galaxy is dark-matter-dominated at all times and radii, BH growth, tied to the baryon cycle, shows no clear correlation with global dynamical properties. Efficient AGN feedback is produced by overmassive BHs relative to extrapolated local $M_\bullet - M_\star$ relations, raising the possibility that dormant, overmassive BHs in local quenched dwarfs and those probed by $\textit{JWST}$ may reflect a common mode of early and rapid BH growth in low-mass galaxies.
[abstract 41 / 70] (score: 2) - Title: The host galaxies and merger environments of short and long GAMMA-RAY BURSTs producing kilonovaeAuthors: Hannah Skobe, Brendan O'Connor, Antonella Palmese, Lewi Westcott, Christopher J. Conselice, Katelyn Breivik,Comments: 25 pages, 10 figures, 4 tables. Submitted and accepted to ApJ. Comments are welcome!Subjects: astro-ph.HE astro-ph.COCreated: 2026-09-18; Updated: 2026-09-22; Datestamp: 2026-09-22
Gamma-ray bursts (GRBs) have traditionally been classified by their prompt emission duration and spectral hardness, with short GRBs (sGRB; $\lesssim2 \ \rm{s}$) originating from compact object mergers and long GRBs (LGRB; $\gtrsim2 \ \rm{s}$) from massive star core-collapse. Recent kilonova (KN) associations with long-duration GRBs have challenged this standard picture. We analyze the host galaxies of nine GRBs with associated kilonova candidates at $z<0.6$, including five sGRB-KNe and four LGRB-KNe. Using both parametric and non-parametric modeling of the host light distributions, we investigate the progenitor environments of these events and test whether their hosts show evidence for recent galaxy interactions that could favor dynamical formation channels or isolated pathways following merger-driven STAR FORMATION episodes for neutron star binaries. We find that five of the nine hosts display tidal features that show they have likely undergone recent mergers, suggesting that merger-driven, dynamical formation pathways may contribute in some systems. We find no clear morphological distinction between sGRB-KN and LGRB-KN hosts as both populations span a wide range of morphologies, including ellipticals, spirals, and interacting systems with tidal features. Multi-Sérsic modeling of the host light profiles further shows that host-normalized offsets inferred from single-Sérsic fits can be overestimated when the transient is associated with a specific subcomponent of a complex host light profile. These results highlight the importance of decomposing host morphology into physically relevant components when interpreting GRB environments and galactocentric offsets.
[abstract 42 / 70] (score: 2) - Title: Anderson Localization of Ion-Temperature-Gradient Modes in Aperiodic StellaratorsAuthors: Amitava Bhattacharjee,Comments:Subjects: physics.plasm-phCreated: 2026-09-20; Updated: 2026-09-22; Datestamp: 2026-09-22
The geometric coefficients of the ion-temperature-gradient (ITG) eigenmode equation along a MAGNETic field line are aperiodic because the line samples the full three-dimensional geometry. Starting from a reduced fluid model for drift waves [Phys. Fluids 26, 880 (1983)], we show that aperiodic stellarator geometry leads to a quasiperiodic Hill equation for the ITG mode structure. In a tight-binding approximation this equation reduces to an Aubry--André--Harper difference equation, suggesting an Anderson-localization mechanism for ITG eigenfunctions. For the continuous equation the localization threshold is identified by the onset of a positive Lyapunov exponent of the transfer matrix at the drift-wave-resonant eigenvalue. The result is a structural property of the eigenvalue problem and is obtained on the drift-wave-resonant branch of the fluid model, at weak global and local MAGNETic shear. We discuss what bearing, if any, this transition may have on the observed clamping of the ion temperature in stellarators, a question that is not settled by this theory.
[abstract 43 / 70] (score: 2) - Title: Discovery of Interpretable Surrogates via Agentic AI: Application to Gravitational WavesAuthors: Tousif Islam, Digvijay Wadekar, Tejaswi Venumadhav, Matias Zaldarriaga, Ajit Kumar Mehta, Javier Roulet, Barak Zackay,Comments: 25 pages, 9 figures, codes available at https://github.com/tousifislam/GWAgentSubjects: gr-qc astro-ph.HE cs.AICreated: 2026-09-20; Updated: 2026-09-22; Datestamp: 2026-09-22
Fast surrogate models for expensive simulations are now essential across the sciences, yet they typically operate as black boxes. We present \texttt{GWAgent}, a large language model (LLM)-based workflow that constructs interpretable analytic surrogates directly from simulation data. Surrogate modeling is well suited to agentic workflows because candidate models can be quantitatively validated against ground-truth simulations at each iteration. As a demonstration, we build a surrogate for gravitational waveforms from eccentric binary BLACK HOLE mergers. We show that providing the agent with a physics-informed domain ansatz substantially improves output model accuracy. The resulting analytic surrogate attains a median Advanced LIGO mismatch of $6.9\times10^{-4}$ together with an $\sim 8.4\times$ speedup in waveform evaluation, surpassing both symbolic regression and conventional machine learning baselines. Beyond producing an accurate model, the workflow identifies compact physical structure from the learned representation. As an astrophysical application, we use \texttt{GWAgent} to analyze the eccentricity of GW200129 and infer $e_{20\mathrm{Hz}}=0.099^{+0.063}_{-0.044}$. These results show that validation-constrained agentic workflows can produce accurate, fast, and interpretable surrogates for scientific simulations and inference.
[abstract 44 / 70] (score: 2) - Title: LHAASO J1849$-$0002: A Hybrid Lepto-Hadronic Interpretation of PeV Gamma-Ray EmissionAuthors: Yihan Shi, Yudong Cui, Lili Yang,Comments: 6 pages, 4 figures, submitted to A&ASubjects: astro-ph.HECreated: 2026-09-21; Updated: 2026-09-22; Datestamp: 2026-09-22
Recently, LHAASO detected gamma-ray emission from the pulsar wind nebula (PWN) J1849-0001 extending up to approximately 2 PeV, providing strong evidence for PeV particle acceleration. To explain the origin of this ultra-high-energy emission, we investigate three physical scenarios: a pure leptonic model, a hadronic-dominated model, and a hybrid lepto-hadronic model. We show that while both pure leptonic and hadronic-dominated models can reproduce parts of the multiwavelength spectral energy distribution (SED), neither can simultaneously explain the entire dataset, particularly the PeV tail. The leptonic scenario requires an unrealistically high electron cutoff energy, while the hadronic model underpredicts the highest-energy emission. We therefore propose a hybrid model that combines inverse Compton emission from PWN electrons with hadronic interactions between escaped COSMIC RAYs and a nearby molecular cloud. In this framework, a suppressed diffusion coefficient ($\sim 1\%$ of the Galactic average) is required to confine PeV particles in the source vicinity. This model successfully reproduces the full SED, including the approximately 2 PeV emission. We further calculate the associated neutrino flux, and show the sensitivity of NEON to this source. Our results support the interpretation that evolved PWNe embedded in complex environments can act as Galactic PeVatrons.
[abstract 45 / 70] (score: 2) - Title: Accretion of a Plasma Vlasov Gas onto a Reissner-Nordström Black HoleAuthors: Yongqiang Liu, Hongsheng Zhang,Comments: V3: Added data figures and numerical resultsSubjects: gr-qcCreated: 2026-09-21; Updated: 2026-09-22; Datestamp: 2026-09-22
We develop a steady-state, spherically symmetric accretion model for a two-component plasma Vlasov gas in the background of a Reissner--Nordström BLACK HOLE. Analytical expressions in parametric form for the critical angular momentum and impact parameter are derived for each species, leading to a rigorous partition of the absorption and scattering domains in phase space. For both monoenergetic and Jüttner distributions, electroMAGNETic attraction enhances, while repulsion suppresses, the particle number density, energy density, pressure and accretion rates of individual charged components relative to the neutral case. After proper normalization, the total physical quantities of the plasma (under non-extreme conditions) can be expressed exactly, or to high accuracy, as weighted averages of the two species. When the two components share identical distribution functions, accretion drives the Reissner--Nordström BLACK HOLE naturally toward the Schwarzschild limit---a charge evolution that is absent in neutral-gas models. Numerical results further reveal that near the horizon the radial pressure is significantly smaller than the tangential pressure, sharply distinguishing the Vlasov gas from a perfect fluid.
[abstract 46 / 70] (score: 2) - Title: Kinematics of the Weak Cool-Core Cluster A3571 Observed with XRISM: Low Cooling Rate Balanced by Low Heating Rate?Authors: Hannah McCall, Irina Zhuravleva, Kyoko Matsushita, Annie Heinrich, Congyao Zhang, Eugene Churazov, William Forman, Ildar Khabibullin, Kotaro Fukushima, Daniele Rogantini, Itsuki Aihara, Christine Jones, Kazunori Suda,Comments: 14 pages, 8 figures. Published in The Open Journal of AstrophysicsSubjects: astro-ph.GA astro-ph.HECreated: 2026-09-21; Updated: 2026-09-22; Datestamp: 2026-09-22
Most XRISM galaxy cluster observations to date have focused on AGN feedback or actively merging systems. The weak cool-core cluster A3571 was observed in four XRISM Cycle 1 pointings, enabling the study of gas kinematics in a relaxed, AGN-feedback-free system. We present measurements of the velocity dispersion and bulk velocity in the core regions of A3571, out to $120$ kpc. The velocity dispersion is relatively uniform across all regions ($\sim100-120 ~\mathrm{km~s^{-1}}$), except in the northern gas sloshing elongation, where a $68\%$ upper limit of $68~\mathrm{km~s^{-1}}$ is obtained. The core Mach number and non-thermal pressure fraction of A3571 are lower than in the extremely relaxed cluster A2029 and below predictions from cosmological simulation suites. Despite relatively low velocity dispersion values, the derived turbulent heating rate (under the assumption of isotropic Kolmogorov turbulence) is sufficient to offset cooling losses within the considerable uncertainties in all studied regions. This suggests that sloshing motions may contribute significantly to the heating budget. Comparing XRISM observations of merging and relaxed clusters, we find that mergers exhibit an average Mach number of $0.29\pm0.07$, nearly twice that of the relaxed sample, which is consistent with predictions from non-radiative cosmological simulations. A3571 is a promising target for resonant scattering studies; however, simulations indicate that deeper observations are required to obtain reliable turbulent velocities via the $z/w$ line ratio.
[abstract 47 / 70] (score: 2) - Title: Splashing-regime transitions and secondary-droplet scaling in oblique drop impacts on a deep poolAuthors: Ying Xiong, Yang Zhang, Lingling Xie, Xiaolei Li,Comments: 28 pages, 13 figuresSubjects: physics.flu-dyn physics.ao-phCreated: 2026-09-19; Updated: 2026-09-22; Datestamp: 2026-09-22
Oblique drop impact onto a deep liquid pool produces asymmetric crowns, directional JETting, and splashing transitions that cannot be characterized by the total impact inertia alone. We numerically investigate water drops impacting a quiescent deep pool over $41\leq We\leq1790$ and $10^\circ\leqθ\leq90^\circ$. The simulations reproduce the principal features observed experimentally and identify five post-impact regimes in the $We$--$θ$ plane: deposition, front splashing, side splashing, side-front splashing, and crown splashing. The deposition--front-splashing transition is described by the tangential-inertial parameter $K_s=We\cosθ$, with $K_s^c\approx120$. This criterion follows from the competition between downstream crown-rim inertia and capillary retraction at the Taylor--Culick velocity. The transition from front to side-front splashing is instead governed primarily by normal impact inertia, with a critical normal Weber number $We_N^c\approx318$. Beyond these regime transitions, the secondary-droplet statistics reveal fragmentation behavior common to the different splashing regimes. The droplet-size distributions are positively skewed, and the median diameter follows $d_{s,\mathrm{med}}/D\sim We^{-3/5}$. Second-order velocity structure functions support a scale-dependent capillary--inertial description of rim and ligament breakup. Combined with mass conservation, this scaling gives $N_s\sim We^{9/5}$, providing a numerical explanation for the secondary-droplet-number scaling observed experimentally. Thus, directional impact inertia governs the macroscopic selection of splashing regimes, whereas the secondary-droplet populations across these regimes exhibit a common capillary--inertial fragmentation scaling.
[abstract 48 / 70] (score: 2) - Title: A pair of unequal JETs imparted the kick velocity to the neutron star of Cassiopeia AAuthors: Dmitry Shishkin, Muhammad Akashi, Noam Soker,Comments: Updated references following reader comments. 16 pages, 8 figures. Comments welcomeSubjects: astro-ph.HECreated: 2026-09-18; Updated: 2026-09-22; Datestamp: 2026-09-22
We analyze observations of the Cassiopeia A core-collapse SUPERNOVA remnant (CCSNR) and identify a pair of opposite rings, attributing their formation to unequal-energy explosion JETs that also imparted the neutron star (NS) its kick velocity via the kick-BEAP (kick by early asymmetrical pair of JETs) mechanism. We replicate the formation of these ring structures, which we identify as circum-JET rings, with three-dimensional hydrodynamical simulations of two opposite explosion JETs in which the northern JET is much more powerful, forming the larger northern ring known as the Crown. The line connecting the centers of the two opposite rings passes through the previously-established point-symmetric center of Cassiopeia A. The momentum difference between the two JETs also explains the observed southwards NS kick velocity of ~400 km/s. The kick-BEAP and point-symmetric morphology suggest powering and shaping by several pairs of JETs during the explosion process, strengthening the jittering JETs explosion mechanism for the Cassiopeia A CCSNR and core-collapse SUPERNOVAe in general.
[abstract 49 / 70] (score: 2) - Title: An experimental and numerical study of the circular hydraulic jumpAuthors: Arnab Kumar Mallik, Hrvoje Jasak, D. Ian Wilson, P. F. Linden, Rajesh K. Bhagat,Comments:Subjects: physics.flu-dynCreated: 2026-09-18; Updated: 2026-09-22; Datestamp: 2026-09-22
This paper describes experiments and numerical simulations on the normal impact of a round liquid JET onto a horizontal surface, such as when water from a tap hits the bottom of a kitchen sink. In this case the liquid impacting on the surface spreads as a fast-flowing thin film and, at some distance from the point of impact, the thickness of the flow abruptly increases and the speed of the flow is reduced. In the experiments studied here the flow is axisymmetric about the axis of the JET, and the abrupt change in depth occurs at a given radius and is known as a circular hydraulic jump (CHJ). We present new experiments in which we measure the thickness of the liquid film inside and beyond the jump and use these measurements to estimate the governing parameters, the Weber, Froude and Reynolds numbers that determine the influence of surface tension, gravity and viscosity, respectively. We also carry out numerical simulations of the flow that show excellent agreement with the experiments and provide independent estimates of these dimensionless parameters. We find that, on the scale of a kitchen sink, and for water at high Reynolds number and low Bond number, at the jump the Weber number is of order unity while the Froude number is large, implying that the jump is controlled by surface tension. We also define a critical dimensionless JET flow rate at which this control no longer holds and gravity plays a significant role.
[abstract 50 / 70] (score: 2) - Title: GRB 220706A: a GAMMA-RAY BURST with a month-long engine and a luminous SUPERNOVAAuthors: Benjamin P. Gompertz, Nusrin Habeeb, Dheeraj R. Pasham, Antonio de Ugarte Postigo, Daniele B. Malesani, Phil A. Evans, Kim L. Page, Ben Rayson, J. Feliciano Agui Fernandez, Michael Bremer, Andrew J. Levan, Genevieve Schroeder, Nial R. Tanvir, Christina C. Thone, Eric Burns, Valerio D'Elia, Massimiliano De Pasquale, Dimple, Dieter Hartmann, Pall Jakobsson, Sylvio Klose, Antonio Martin-Carrillo, Matt Nicholl, Ana M. Nicuesa Guelbenzu, David O'Neill, Giovanna Pugliese, Arne Rau, Andrea Rossi, Jesper Sollerman, Rhaana Starling, Darach Watson, Isabelle Worssam, Makenzie E. Wortley,Comments: 22 main article pages, excl. references. 5 main article figures, 1 supplementary figure. 1 main article table, 1 extended data table, 3 supplementary tablesSubjects: astro-ph.HECreated: 2026-09-18; Updated: 2026-09-22; Datestamp: 2026-09-22
While the progenitors of many long GAMMA-RAY BURSTs (GRBs) are well established as the core collapse of very massive, envelope-stripped, rapidly-rotating stars, it has been suggested that bursts at the extremely long end of the duration distribution may be a separate population of `ultra-long' GRBs. With durations of thousands of seconds or more, these bursts are difficult to reconcile with the engine timescales expected from the compact Wolf-Rayet stars that are typically assumed to produce more `standard' long GRBs. Here, we present observations of GRB~220706A, where X-ray follow-up reveals flaring episodes that last until $\approx 51$ days after trigger. At the measured redshift of $z = 0.8577$, this corresponds to 27 days in the GRB rest frame, and represents the latest central engine activity ever observed in a GRB by a margin of $\approx 21$ rest-frame days. We also identify a likely SUPERNOVA (SN) which, when accounting for the inferred optical extinction of $0.9 \leq A_V \leq 3.6$ mag (constrained by indirect arguments), has a peak absolute magnitude of $M_r \leq -20.25$, resembling the energetic SN\,2011kl found accompanying ultra-long GRB\,111209A, and consistent with super-luminous SNe. We discuss the implications GRB~220706A has for ultra-long GRB progenitor models and possible powering mechanisms for the extremely late central engine activity.
[abstract 51 / 70] (score: 2) - Title: Star Formation and Nebular Attenuation from Pa$α$, Br$α$, and Br$β$ in Massive Dust-obscured Galaxies at Cosmic Noon using JWSTAuthors: Virginia Vanicek, Jed McKinney, Alexandra Pope, Anna Sajina, Stacey Alberts, Meredith Stone, Lee Armus, Sinclaire M. Manning, Olivia Cooper, Tanio DÍaz-Santos, Miriam Eleazer, Caitlin Casey, Thomas S. -Y. Lai, Steven Finkelstein, Leonid Sajkov, Allison Kirkpatrick, Anthony Taylor,Comments: 15 pages, 10 figuresSubjects: astro-ph.GACreated: 2026-09-18; Updated: 2026-09-22; Datestamp: 2026-09-22
Near-infrared hydrogen recombination lines can provide robust star-formation rates if the effects of dust attenuation continue to diminish towards longer wavelengths. To quantify near-infrared attenuation and ultimately measure accurate star-formation rates (SFRs) at the height of cosmic star-formation, we present Pa$α$, Br$α$, and Br$β$ detections in $27$ luminous infrared galaxies at $z\sim 1-2$, including pure star-forming galaxies as well as dust-obscure Active Galactic Nuclei (AGN). Using combined spectra from the JWST MIRI (Mid-Infrared Instrument) LRS (Low Resolution Spectrometer) and the Spitzer Space Telescope IRS we quantify the STAR FORMATION rates of our sample using a sub-sample of 13 galaxies detected in Pa$α$ emission ($1.87\, μ$m), 14 galaxies detected in Br$α$ ($4.05\, μ$m), and 12 galaxies detected in Br$β$ ($2.63\, μ$m). By combining multiple near-infrared recombination lines in individual galaxies we calculate nebular attenuation, finding $A_λ\sim3$ mag at $\sim2\,μ$m and $A_λ\sim1$ mag at $\sim4\,μ$m. Nebular lines trace the SFR on $\sim 10$ Myr timescales, which we compare to the total infrared luminosity ($L_{\rm IR}$) which probes the STAR FORMATION over the last $\sim 100$ Myr. SFRs measured from $L_{\rm IR}$ using common conversions are systematically higher than the SFRs derived from attenuation-corrected nebular line measurements by a factor of $\sim2.5$. This could be indicative of a declining or static STAR FORMATION history with a past burst or systematic effects on $\rm SFR_{\rm IR}$ such as dust heating from evolved stellar populations, and/or an ACTIVE GALACTIC NUCLEus.
[abstract 52 / 70] (score: 2) - Title: Inflated Supermassive Stars as Little Red Dots and Progenitors of Supermassive Black HolesAuthors: Wenbin Lu,Comments: 29 pages, 17 figures, plus appendixSubjects: astro-ph.SR astro-ph.GA astro-ph.HECreated: 2026-09-18; Updated: 2026-09-22; Datestamp: 2026-09-22
JWST has uncovered an abundant population of compact, red sources at high redshifts, termed little red dots (LRDs). We study whether they could be explained by thermally relaxed, hydrogen-burning, metal-enriched supermassive stars (SMSs). We construct 1D models in hydrostatic and thermal equilibrium, including a radiation-pressure-dominated, CNO-burning core and an outer envelope with metallicity-dependent opacity, non-adiabatic convection, and an effective treatment of super-Eddington surface layers. The luminosity is close to the Thomson-scattering Eddington limit. The Fe-opacity bump drives the formation of a strongly inflated, low-mass envelope, while hydrogen recombination terminates the envelope at a bound photosphere. For M=$10^4$ to $10^6$ Msun and metal mass fractions $Z=10^{-4}$ to $10^{-2}$, we find that the most metal-rich models (Z ~ $10^{-2}$) develop highly inflated envelopes and reach Teff ~ 7000 K. We suggest that such enriched SMSs could instead be assembled through runaway stellar collisions in compact star clusters. The GR instability sets a maximum mass that depends on the core rotation rate. The nonrotating and rotating models have maximum masses $3\times10^5$ to $3\times 10^6$ Msun, and maximum luminosity of the order $10^{44}$ erg/s, comparable to the observed bright-end cutoff of the LRD luminosity function. Core hydrogen depletion can drive initially stable SMSs across the instability threshold after a lifetime of order 1 Myr. If each LRD leaves a BLACK HOLE retaining most of its mass, the observed LRD abundance implies a present-day remnant density of order $10^{-2}\rm cMpc^{-3}$, consistent with the local abundance of supermassive BLACK HOLEs. Cool SMSs naturally produce weak X-ray and weak high-ionization lines. Non-LTE effects may significantly modify the Balmer features and the continuum opacity, and may lower Teff below our LTE value.
[abstract 53 / 70] (score: 2) - Title: The chirping of Lense-Thirring precession in tidal disruption event accretion flowsAuthors: Andrew Mummery, Eliot Quataert,Comments: 19 pages, 6 figures. Submitted to ApJSubjects: astro-ph.HECreated: 2026-09-18; Updated: 2026-09-22; Datestamp: 2026-09-22
Tidal disruption event X-ray light curves do not appear to show clear signs of periodic modulation. This is naively somewhat surprising since the stars that are disrupted originate at large scales in the galaxy where they cannot know about the orientation of the BLACK HOLE spin axis. This should lead to the formation of a misaligned disk that precesses due to Lense-Thirring torques, modulating X-ray emission from the inner disk regions. We argue that in fact the properties which are required for solid-body precession, namely a thick $(H/R\sim {\mathcal O}(1))$ disk, naturally lead to rapid precession period change, with a per-period increase of $ΔT_{\rm prec}/T_{\rm prec} \sim {\mathcal O}(1-10)$, as the disk spreads to larger radii to conserve angular momentum. In other words the precession of thick TDE disks is aggressively chirped, washing out any possibility of observing multiple cycles other than for fine tuned regions of parameter space. The global disk alignment timescale is equally strongly chirped by the exact same mechanism, meaning that TDE disks will not in general align with the BLACK HOLE spin axis during a super-Eddington phase, and should generically show global quasi-steady warp profiles at the beginning of any thin disk phase. These results have important implications for interpreting timing features associated with TDE disks, including models for quasi-periodic X-ray eruption timing phenomenology, and the observational properties of TDE disks in the initial transition to the thin disk phase.
[abstract 54 / 70] (score: 2) - Title: Resolving the Galactic Center Region's Gamma-Ray Emission and Searching for its Neutrino Counterpart with HAWC and IceCubeAuthors: S. Yun-Carcamo, R. Babu, for the HAWC, IceCube collaborations,Comments:Subjects: astro-ph.HECreated: 2026-09-18; Updated: 2026-09-22; Datestamp: 2026-09-22
The Galactic Center (GC) is a prime candidate for petaelectronvolt cosmic-ray acceleration, with gamma-ray emission observed by the High Altitude Water Cherenkov (HAWC) Observatory extending beyond 100 TeV. We present an analysis of the GC using ~2860 days of HAWC data, with increased exposure and improved sensitivity relative to previous results. The best-fit gamma-ray emission model includes a point source (HAWC J1745-2857) and a Galactic diffuse emission component. Assuming a hadronic origin, we construct the corresponding neutrino signal template and search for it in 12 years of IceCube muon-track data. No significant neutrino excess is found, and we report the first upper limit on the high-energy neutrino flux associated with the multi-component spatial model of the GC derived from HAWC data. The limit is approximately 12 times the nominal neutrino flux predicted from the HAWC gamma-ray model under a hadronic interpretation, and therefore it does not yet test the optically thin hadronic scenario.
[abstract 55 / 70] (score: 2) - Title: Interactions Between Two Magnetized Plasma Pressure Filaments: Drift-Alfvén Modes and TransportAuthors: Thomas Simala-Grant, Scott Karbashewski, Richard Sydora, Bart Van Compernolle,Comments: 11 pages, 14 figuresSubjects: physics.plasm-ph physics.space-phCreated: 2026-09-18; Updated: 2026-09-22; Datestamp: 2026-09-22
A set of experiments on merging dynamics of localized MAGNETized plasma pressure filaments in close proximity has been carried out in a large linear MAGNETized plasma device. A two filament configuration is used to determine the separation scale of cross-field interaction. Fluctuation analysis of the ion saturation current confirms the presence of unstable drift-Alfvén modes on each filament which are predominantly driven by the steep electron temperature gradient. When the filaments are separated a distance of approximately five times the size of a single filament or greater, no interaction is observed and the drift-Alfvén modes remain uncoupled. When brought closer together, significantly stronger interaction occurs with transfer of charge and energy, leading to the generation of inter-filament electric fields. This has the effect of rotating the filaments and influencing the merging dynamics. When the filaments are asymmetrically heated, the cooler filament becomes wrapped around the other, and the drift-Alfvén modes become fully coupled in a global mode structure. Transport between the filaments is explained in terms of E x B drift and the local potential wells of the filaments, and drift-Alfvén mode coupling occurs when the filaments are brought within the distance of a collisionless skin depth.
[abstract 56 / 70] (score: 2) - Title: Dust Growth in Evolving Filamentary Molecular Clouds: Signatures in Ionization, Resistivity, and Infrared ScatteringAuthors: Hayato Uchimura, Yoshiaki Misugi, Daisuke Takaishi, Taishi Tsuchiyama, Tomoki Tokunaga, Rintaro Shibakawa, Yusuke Tsukamoto,Comments: Accepted for publication in The Astrophysical JournalSubjects: astro-ph.GA astro-ph.SRCreated: 2026-09-19; Updated: 2026-09-22; Datestamp: 2026-09-22
Studies of dust growth in molecular clouds often prescribe the collapse history, leaving unclear how MAGNETic regulation of core formation shapes dust evolution and its observable and non-ideal MHD signatures. We address this problem by performing one-zone dust evolution and ionization calculations along time-dependent density and MAGNETic-field histories extracted from three-dimensional non-ideal MHD simulations of core formation through filament fragmentation. A stronger initial MAGNETic field delays contraction and thereby gives dust grains more time to grow at a given density. In our models, this delayed contraction leads to mass-weighted mean dust sizes of $1.2\,μ\mathrm{m}$ and $3.1\,μ\mathrm{m}$ at $n_{\mathrm{H}}=10^6\,\mathrm{cm^{-3}}$ for $B_{\mathrm{ini}}=20$ and $50\,μ\mathrm{G}$, respectively. The associated depletion of very small dust grains reduces the adsorption of charged particles onto dust grain surfaces and lowers the conductivity: relative to models without dust growth, the ionization fraction increases from $\sim10^{-9}$ to $\sim10^{-8}$, the ambipolar resistivity increases, and the ion--neutral drift velocity rises to several $\mathrm{m\,s^{-1}}$ in the weak-MAGNETic-field model and approximately $10\,\mathrm{m\,s^{-1}}$ in the strong-MAGNETic-field model. These drift velocities remain below the observationally suggested range of $30$--$100\,\mathrm{m\,s^{-1}}$, indicating that still stronger MAGNETic fields may be required. The evolved dust populations also attain single-scattering albedos of order $ω_λ\sim0.8$ at $3.6$--$4.5\,μ\mathrm{m}$, with the stronger field shifting the onset of efficient infrared scattering toward lower densities. These results demonstrate that the MAGNETically controlled collapse timescale, rather than density alone, links dust growth to ionization, ambipolar diffusion, and infrared scattering in prestellar cores.
[abstract 57 / 70] (score: 2) - Title: The MAGNETic field in the multi-phase interstellar medium of NGC 6946Authors: Amir Yarahmadi, Fatemeh Tabatabaei, Golshan Ejlali, Rainer Beck, Enrique Lopez-Rodriguez, Alejandro Borlaff,Comments: 26 pages, 14 figures; accepted for publication in ApJSubjects: astro-ph.GACreated: 2026-09-19; Updated: 2026-09-22; Datestamp: 2026-09-22
Magnetic fields regulate the multi-phase interstellar medium (ISM) of spiral galaxies, yet their behavior across ISM phases remains poorly constrained observationally. We present a comparative polarimetric study of the nearby spiral galaxy NGC 6946 using far-infrared (FIR) data at 154 $μ$m from SOFIA/HAWC+ and radio continuum data at 6 cm from the VLA and Effelsberg telescopes, which probe MAGNETic fields in the cold dust-emitting and diffuse SYNCHROTRON-emitting phases of the ISM, respectively. The SYNCHROTRON POLARIZATION reveals a coherent large-scale spiral MAGNETic field, with high POLARIZATION fractions in interarm regions and strong dePOLARIZATION in star-forming arms. The FIR POLARIZATION fraction is lower on average and shows stronger spatial variations. Both tracers decrease systematically with increasing STAR FORMATION activity, indicating that star-formation-driven turbulence reduces MAGNETic field ordering; the SYNCHROTRON POLARIZATION fraction is strongly suppressed in the central kiloparsec but stable across the mid disk, with a tendency to increase beyond $R \approx 7$ kpc, while the FIR POLARIZATION fraction remains low ($\sim$2-3%) and approximately constant over the radial range where it can be reliably measured ($R \lesssim 5.4$ kpc). Our results indicate that NGC 6946 hosts a globally ordered MAGNETic field locally modulated by turbulence. This study highlights the complementary nature of FIR and radio polarimetry in probing MAGNETic fields across ISM phases and provides quantitative constraints on how MAGNETic field ordering varies between the cold and diffuse ISM components.
[abstract 58 / 70] (score: 2) - Title: Probing BLACK HOLEs surrounded by Dust field in Quantum Fluctuation Modified Gravity with twin-peak QPOsAuthors: Kamola Shermatova, Qodir Badalov, Abubakir Shermatov, Javlon Rayimbaev, Bekzod Rahmatov, Shokhzod Jumaniyozov, Dilafruz Xujanova, Farhod Nuraliev,Comments:Subjects: gr-qcCreated: 2026-09-19; Updated: 2026-09-22; Datestamp: 2026-09-22
We study a static, spherically symmetric BLACK HOLE solution surrounded by a dust field within quantum fluctuation modified gravity, in which the quantum-fluctuation parameter $α$ and the dust-field strength parameter $K$. The horizon structure reveals the two parameters acting in opposite directions: strengthening $K$ draws the inner and outer horizons together until they merge into a single extremal horizon, while a larger $α$ restores the Schwarzschild limit; the same opposing trend extends to the effective potential and the characteristic circular-orbit radii -- the innermost stable circular orbit, the marginally bound orbit, and the marginal circular orbit -- which shift inward with $K$ and outward with $α$, and to the Keplerian and radial epicyclic frequencies of massive test particles. From these frequencies we build three twin-peak quasi-periodic oscillation models -- RELATIVISTIC precession, warped-disk, and epicyclic-resonance -- along with their $3{:}2$, $4{:}3$, and $5{:}4$ resonance radii, all following the same $K$-$α$ trend. Testing all three models against twin-peak QPO data from two stellar-mass (GRO~J1655$-$40, XTE~J1550$-$564) and two intermediate-mass (M82~X$-$1, NGC~1313~X$-$1) sources through a Markov Chain Monte Carlo analysis places best-fit constraints, at the $2σ$ level, of $K\in(0,0.5)$ and $α\in(0.3,0.6)$ across all sources and models.
[abstract 59 / 70] (score: 2) - Title: Scalar Dissipation Criticality in Compressible Magnetized TurbulenceAuthors: Svitlana Mayboroda, David N. Spergel, Camillo De Lellis,Comments:Subjects: physics.plasm-ph astro-ph.GA physics.flu-dynCreated: 2026-09-19; Updated: 2026-09-22; Datestamp: 2026-09-22
We extend the Obukhov-Corrsin theory of scalar turbulence to compressible flows with spatially variable, anisotropic diffusivity. Combining density and diffusivity into a single positive matrix field, a transport landscape, permits an exact scale-by-scale balance in which the sign-indefinite commutator between filtering and diffusion is eliminated rather than estimated. If the density-weighted third-order velocity and scalar increments scale as $\ell^α$ and $\ell^β$, respectively, we prove that anomalous scalar dissipation is impossible when $α+2β>1$. Remarkably, this threshold is independent of the anisotropy and spatial regularity of the diffusivity, provided it remains uniformly elliptic. Codimension-one shocks in both velocity and scalar have $α=β=1/3$ and therefore lie exactly at the critical threshold. For statistically stationary turbulence we further obtain an exact density-weighted constant-flux relation, providing a compressible analogue of the relation underlying Yaglom's law. The results apply directly to passive-scalar transport in both gases and MAGNETized plasmas and provide testable diagnostics for simulations of compressible MAGNETohydrodynamic turbulence. Because the same operator governs anisotropic heat conduction, the results carry over to the electron temperature of a MAGNETized plasma, and they imply that gradient statistics in such flows must be contracted with the transport landscape rather than with the density.
[abstract 60 / 70] (score: 2) - Title: A dynamic MAGNETo-ionic environment around a long-period radio transientAuthors: Botao Li, Yongjie Jin, Shike Qu, Chaohua Gao, Wei Wang, Pei Wang, Shumei Jia, Jifeng Liu,Comments: 28 pages, 3 figures plus 6 figures in the methods, the initial submission on July 12, comments are welcomeSubjects: astro-ph.HE astro-ph.SRCreated: 2026-09-20; Updated: 2026-09-22; Datestamp: 2026-09-22
Faraday rotation provides one of the most direct probes of MAGNETized plasma along the line of sight, from the large-scale Galactic MAGNETic field to compact plasma environments local to radio sources. In particular, temporal variations in rotation measure can trace changes in the density, MAGNETic-field strength, or geometry of the Faraday-rotating medium, as observed in radio pulsars and fast radio bursts. Long-period radio transients (LPTs), a recently identified class of coherent radio sources with periods of hundreds to thousands of seconds, remain poorly explored because their physical nature is still uncertain. Here we present full-Stokes observations of the 421-s LPT source CHIME J0630+25 and report, for the first time, extreme rotation measure (RM) variability from approximately -400 to -1630 rad m^-2. The rapid RM changes occur on short timescales, including a difference of approximately 50 rad m^-2 between two consecutive rotation periods and a sudden change of approximately 536 rad m^-2 within approximately 2500 s. Compared with other radio-emitting sources, CHIME J0630+25 occupies an unusual region of the DM-RM plane: despite its very small DM of approximately 22 pc cm^-3, |RM| reaches over 1.6 x 10^3 rad m^-2, far exceeding that expected from the interstellar medium and pulsars. The fast and large-amplitude RM variations should arise from a compact, structured, and rapidly evolving MAGNETo-ionic environment local to the source, possibly associated with a compact binary system.
[abstract 61 / 70] (score: 2) - Title: The role of photon fields of local sources in the formation of the COSMIC RAYs energy spectrumAuthors: S. E. Pyatovsky, S. K. Machavariani,Comments:Subjects: astro-ph.HECreated: 2026-09-20; Updated: 2026-09-22; Datestamp: 2026-09-22
The influence of photon fields of local sources (LS) on the formation of the COSMIC RAY (CR) energy spectrum (E0) is considered. A model for the formation of irregularities in the CR spectrum, based on the local source model, is proposed. It is shown that the CR spectrum can be formed as a sum of partial spectra formed near local CR sources during the passage of primary cosmic radiation (PCR) through the photon fields of the sources. Local sources can be the most active stars of various types of variability in the stellar population, - from dwarfs to hypergiants. Studies have shown that the so-called "bump" near E0 = 100 PeV is formed in the photon fields of Mira-type variable stars, which are typically multiple stellar systems, consisting of a red giant and a white dwarf.
[abstract 62 / 70] (score: 2) - Title: Effects of particle-induced electron emission on transport properties in electrically-biased plasma sheaths under fusion-relevant conditionsAuthors: Lucio Murillo, Chirag Skolar, Kolter Bradshaw, Bhuvana Srinivasan,Comments:Subjects: physics.plasm-phCreated: 2026-09-20; Updated: 2026-09-22; Datestamp: 2026-09-22
A rigorous implementation of energy-dependent ion- and electron-induced electron emission in a continuum-kinetic framework is used to reveal their effects on the scaling of plasma properties in the sheath with an applied bias potential to the walls. The approach comes with a novel methodology for modeling particle-induced electron emission (PIEE) that includes 1) improved fitting functions for the yield and spectra, 2) the use of SRIM and a summation of the Lindhard formula and a modified Bethe formula for obtaining accurate stopping powers, and 3) a binding energy correction to the PIEE spectra and ion-induced yield based on density functional theory (DFT) calculations. The emission models are implemented as a fully energy dependent and dynamic boundary condition. For this investigation, tungsten and graphite walls are studied for their relevance in MAGNETic fusion experiments. Equations are derived from fluid theory that predict the relative importance of ion- and electron-induced emission on the structure of the sheath. The simulations provide evidence for the theoretical predictions, showing that a transition from a classical to space-charge limited (SCL) sheath depends primarily on electron-induced emission. Furthermore, claims in previous literature of increased heat and particle loads to the walls due to electron emission are supported, however differing mechanisms for the increase are observed. The increased thermal and particle fluxes due to PIEE are primarily driven by collisional transfer of energy from emitted electrons in the presheath. Finally, quantitative predictions for the device modeled in this study coincide with previous modeling efforts and experimental measurements.
[abstract 63 / 70] (score: 2) - Title: Chaos-induced transport due to electrostatic-fluctuations in a toroidal plasmaAuthors: Andres E. Medrano-Albarran, Julio J. Martinell,Comments: 16 pages, 11 figuresSubjects: physics.plasm-phCreated: 2026-09-20; Updated: 2026-09-22; Datestamp: 2026-09-22
Plasma transport produced by electrostatic fluctuations is studied using a test particle model in a toroidal geometry. A model wave spectrum is assumed which introduces a time dependence in the Hamiltonian description of particle motion in the strong MAGNETic field. This allows for the existence of chaotic particle motion which gives rise to transport processes. Another way of producing transport is by introducing a stochastic process inside the wave spectrum. The two possibilities are explored and it is shown that both cases give rise to diffusive transport. The presence of chaotic motion is corroborated by computing approximate Lyapunov exponents. Additionally the presence of zonal flow is considered which can give rise to a transport barrier by suppressing radial particle fluxes, in the cases that show chaotic transport. This effect gives support to the existence of chaotic motion as responsible for transport since it reproduces the behavior of the robust invariant torus resilience to chaos, acting as a transport barrier, observed in Hamiltonian models of chaos.
[abstract 64 / 70] (score: 2) - Title: Physics-Informed Kolmogorov-Arnold Networks for Grad-Shafranov Tokamak EquilibriaAuthors: D. A. Kaltsas, A. Kuiroukidis, J. Liu, L. Magafas, G. N. Throumoulopoulos,Comments:Subjects: physics.plasm-ph physics.comp-phCreated: 2026-09-20; Updated: 2026-09-22; Datestamp: 2026-09-22
We employ equation-driven, physics-constrained deep learning to solve the fixed-boundary Grad-Shafranov (GS) equilibrium problem, constructing axisymmetric MAGNETohydrodynamic equilibria with tokamak-relevant characteristics. Equilibria across linear (Solov'ev) and nonlinear profile functions are constructed using Physics-Informed Kolmogorov-Arnold Networks (KANs) that approximate GS solutions while satisfying appropriate boundary conditions. A highly nonlinear pressure profile recreating high-confinement mode phenomenology, such as pressure pedestals and significant bootstrap current components, is also considered. To enable efficient convergence, guided training schemes are employed, specifically homotopy-based continuation curriculum learning and transfer learning via pretrained networks. While computing nonlinear equilibria employing standard Multi-Layer Perceptrons under unguided physics-informed training remains an elusive or computationally inefficient task, our framework overcomes this limitation. Specifically, we demonstrate that the combination of three key elements, namely KAN architecture, guided training schemes, and the self-scaled Broyden optimization method, enables stable, efficient, and accurate equilibrium computation with simultaneous profile parameter identification in view of equilibrium constraints.
[abstract 65 / 70] (score: 2) - Title: The CAMELS-CROCODILE Simulation Suite: A New Cosmology--Astrophysics Playground for Machine LearningAuthors: Kentaro Nagamine, Yuri Oku, Atsushi J. Nishizawa, Jun-Young Lee, Francisco Villaescusa-Navarro, Shy Genel, Daniel Anglés-Alcázar,Comments: 26 pages, 10 figures, submittedSubjects: astro-ph.GA astro-ph.COCreated: 2026-09-21; Updated: 2026-09-22; Datestamp: 2026-09-22
We present CAMELS-CROCODILE, a suite of cosmological hydrodynamic simulations that extends the CAMELS framework with the \gadget{} smoothed particle hydrodynamics code and the Osaka feedback model. As a companion to the IllustrisTNG-based second-generation CAMELS suite, it provides an independent implementation of the baryonic physics that shapes galaxies, the intergalactic medium, and large-scale structure, broadening the range of subgrid models over which machine-learning (ML) inference can be marginalized and tested. The suite comprises $25$ and $50Mpc/h$ boxes organized into one-parameter, cosmic-variance, and Sobol-sequence sets that vary $26$ cosmological and astrophysical parameters around a fiducial Osaka model. We describe the simulation design and validate the suite against benchmarks and other CAMELS suites. Compared with IllustrisTNG, the fiducial model suppresses the matter power spectrum by only a few per cent, against up to ${\sim}27\%$ at $z=0$, and forms stars with similar efficiency below $10^{12.2} M_\odot/h$ but up to $2.5$ times more efficiently in group-scale halos, both consistent with weaker AGN feedback. We also present the stellar and BLACK HOLE bias and the Ly$α$ absorption around galaxies. As a first ML application, we apply a graph neural network trained on IllustrisTNG galaxy catalogs, with frozen weights, to CAMELS-CROCODILE. It fails to recover $Ω_{\rm m}$ and $σ_8$ and returns overconfident posteriors, mainly for simulations containing more galaxies than any in its training set; within that range $Ω_{\rm m}$ is recovered with an error only $1.5$ times the in-distribution value. These results underline the need to train and test ML inference across physically distinct galaxy formation models.
[abstract 66 / 70] (score: 2) - Title: Constraints on Axion-like Dark Matter from Cosmic Birefringence with a Polarization Array of Repeating Fast Radio BurstsAuthors: Xiaohui Liu, Zi-Yan Yuwen, Yun-Long Zhang, Zerui Liu, Shiqian Zhao, Shuai Feng, Wei-Yang Wang, Xuelei Chen,Comments: 23 pages, 4 figuresSubjects: astro-ph.HE hep-phCreated: 2026-09-21; Updated: 2026-09-22; Datestamp: 2026-09-22
Axion-like DARK MATTER (ALDM) is a well-motivated DARK MATTER candidate whose Chern-Simons coupling to photons can induce cosmic birefringence, producing temporal oscillations and spatial correlation in POLARIZATION angle (PA) signals from different sources. Hyperactive repeating fast radio bursts (FRBs) with high linear POLARIZATION are a particularly promising probe of such signatures. We develop a Bayesian framework to search for PA oscillations caused by ALDM in individual repeating FRBs, and combine multiple sources in an FRB POLARIZATION array (FRBPA) by exploiting correlations arising from the common Earth term. We apply this framework to PA datasets from three well-studied hyperactive repeating FRBs, and constrain the Chern-Simons coupling over a broad range of ALDM masses. For each FRB, we estimate the DARK MATTER density at its host location using a simulation-calibrated halo profile. The inferred DARK MATTER densities are comparable to the fiducial local density $ρ_0 = 0.4~\mathrm{GeV/cm^3}$. The comparable source and Earth DARK MATTER densities, together with the redshift-induced difference between the frequencies of the source and Earth terms, motivate our adoption of the full two-component birefringence model. We find no compelling evidence for ALDM-induced PA oscillations in either the individual source analyses or the joint FRBPA analysis. We place 95\% credible upper limits on the Chern-Simons coupling strength as a function of ALDM mass. Across the axion mass from $10^{-23}$ to $10^{-18}~\mathrm{eV}$, the resulting upper limits of the coupling strength of FRBPA lie between $10^{-12.6}$ and $10^{-7.9}~\mathrm{GeV}^{-1}$. Our results establish long-term polarimetric monitoring of hyperactive repeating FRBs as a promising and independent probe of ALDM, with sensitivity expected to improve with longer observational baselines and larger source samples.
[abstract 67 / 70] (score: 2) - Title: Geodesic Acoustic Modes in pair plasmas confined in tokamak MAGNETic fieldsAuthors: Alessandro Biancalani,Comments:Subjects: physics.plasm-phCreated: 2026-09-21; Updated: 2026-09-22; Datestamp: 2026-09-22
This paper is devoted to the derivation of the dispersion relation of the Geodesic Acoustic Mode in pair plasmas, i.e. assuming that ions and electrons have the same mass. Geodesic Acoustic Modes are plasma perturbations playing a crucial role in turbulence regulation, and therefore in the determination of the plasma confinement in tokamaks. Experiments with pair plasmas, like electron-positron plasmas, have been proposed with different kinds of confinements, and aim to study fundamental processes in plasma physics and understanding the formation of the early universe.
[abstract 68 / 70] (score: 2) - Title: Rotating Radio Transient Phases of Isolated Neutron Star Systems and Descendants of Central Compact ObjectsAuthors: Ş. Demirok, Ü. Ertan, A. A. Gençali,Comments: Accepted for publication in MNRAS, 10 pages, 4 figuresSubjects: astro-ph.HECreated: 2026-09-21; Updated: 2026-09-22; Datestamp: 2026-09-22
Rotating radio transients (RRATs) form an isolated neutron star (INS) population characterized by their sporadic and short radio bursts. In the fallback disc model, it was suggested that most INS populations pass through an RRAT phase during their evolution, and the mechanism producing these bursts could be the enhancement of the flux of open MAGNETic field lines through the poles of dead pulsars due to penetration of the inner disc into the light cylinder. To test this idea, we determine the RRAT phases that could be produced by this mechanism along the evolutionary curves of the INS families on the period-period derivative ($P$--$\dot{P}$ diagram). These RRAT phases form an RRAT region in the $P$--$\dot{P}$ diagram, which is in agreement with the known RRAT distribution. Using our results, we also investigate the descendants of central compact objects (CCOs). We estimate that the CCOs similar to the three CCOs with measured $P$ and $\dot{P}$ are not likely to become radio pulsars (RPs). The situation is rather different for Calvera, a recently identified CCO. In the model, Calvera-like sources become RPs with lifetimes $ > 10^{8}$ yr. Indeed, there is a cluster of RPs in the region of \PPdot~diagram where descendants of Calvera-like CCOs evolve in our model. We also estimate that they have a very low birth rate, and therefore their immediate descendants may not currently exist in our Galaxy.
[abstract 69 / 70] (score: 2) - Title: IceCube Upgrade status and perspectivesAuthors: Anna Eimer,Comments: Presented at the 14th Cosmic-Ray International Studies and Multi-messenger Astroparticle Conference (CRIS-MAC 2026)Subjects: astro-ph.IM astro-ph.HECreated: 2026-09-21; Updated: 2026-09-22; Datestamp: 2026-09-22
The IceCube Neutrino Observatory instruments one cubic kilometer of deep-glacial ice between 1450 m and 2450 m below the surface at the geographic South Pole to detect neutrinos via Cherenkov radiation of RELATIVISTIC charged particles produced in their interactions. This detector is responsible for a number of key observations in neutrino astrophysics, which include the discovery of a high-energy astrophysical neutrino flux and, more recently, the galactic plane. During the austral summer of 2025/26, five new strings equipped with new photosensor designs were deployed as a dense infill in the middle of the existing detector. The science goals of this detector are twofold: Firstly, given the higher photocathode density, an improved atmospheric neutrino event selection and reconstruction at a few GeV can be achieved for enhanced capabilities to study neutrino oscillations. Secondly, novel calibration devices will improve the knowledge of the optical properties of the glacial ice and the detector response. These new calibration results will be applied to archival IceCube data, improving angular and spatial resolution of all detected astrophysical neutrino events. The IceCube Upgrade also serves as a first step towards the next-generation neutrino telescope at the South Pole, called IceCube-Gen2.
[abstract 70 / 70] (score: 2) - Title: Oblique kink waves in solar coronal streamersAuthors: Aleksandr V. Rubtsov, Valery M. Nakariakov, Dmitri Yu. Klimushkin, Ding Yuan,Comments:Subjects: astro-ph.SR physics.plasm-phCreated: 2026-09-21; Updated: 2026-09-22; Datestamp: 2026-09-22
Coronal streamer kink waves excited by an impact of coronal mass ejections (CMEs) are routinely used to estimate the coronal Alfvén speed. These estimates generally assume wave propagation parallel to the equilibrium MAGNETic field directed radially outward to the Sun, in the plane of the sky. However, the geometry of CME impacts naturally allows for oblique propagation. We investigate the properties of obliquely propagating kink waves guided by a plasma slab with a central current sheet representing a coronal streamer stalk. We consider both cold and warm streamer plasmas and analyse influence of propagation obliquity on wave dispersion, eigenfunctions, and seismological diagnostics. We find that increasing the propagation obliquity reduces the phase speed owing to both projection effects and the intrinsic dependence of the phase speed on the propagation angle. The wave structure also undergoes a gradual transition from a body mode to a surface mode, leading to stronger perturbations at the slab boundaries and enhanced wave localization. Consequently, for a given energy deposited by a CME impact, oblique kink waves are expected to produce larger observable amplitudes than field-aligned waves. Applying the developed theory to streamer waves reported previously, we infer Alfvén speeds in the range of 50-500 km/s. We show that neglecting wave propagation obliquity may underestimate the Alfvén speed by up to a factor of 1.5. These results demonstrate that wave propagation obliquity should be taken into account in coronal seismology of streamer waves and that stereoscopic observations will be required to constrain the true propagation direction.
arXiv:2606.25868 [pdf, ps, other]
arXiv:2609.24633 [pdf, ps, other]
arXiv:2609.23824 [pdf, ps, other]
arXiv:1903.07329 [pdf, ps, other]
arXiv:2609.23410 [pdf, ps, other]
arXiv:2609.24735 [pdf, ps, other]
arXiv:2606.22559 [pdf, ps, other]
arXiv:2609.22433 [pdf, ps, other]
arXiv:2609.22449 [pdf, ps, other]
arXiv:2609.24005 [pdf, ps, other]
arXiv:2605.23818 [pdf, ps, other]
arXiv:2607.10167 [pdf, ps, other]
arXiv:2609.22421 [pdf, ps, other]
arXiv:2507.00870 [pdf, ps, other]
arXiv:2512.03281 [pdf, ps, other]
arXiv:2607.12776 [pdf, ps, other]
arXiv:2609.22434 [pdf, ps, other]
arXiv:2609.22660 [pdf, ps, other]
arXiv:2606.15674 [pdf, ps, other]
arXiv:2609.22424 [pdf, ps, other]
arXiv:2511.16291 [pdf, ps, other]
arXiv:2603.25413 [pdf, ps, other]
arXiv:2606.31477 [pdf, ps, other]
arXiv:2607.10267 [pdf, ps, other]
arXiv:2607.12291 [pdf, ps, other]
arXiv:2609.14264 [pdf, ps, other]
arXiv:2609.22436 [pdf, ps, other]
arXiv:2609.22480 [pdf, ps, other]
arXiv:2609.22787 [pdf, ps, other]
arXiv:2609.22859 [pdf, ps, other]
arXiv:2609.23187 [pdf, ps, other]
arXiv:2609.24335 [pdf, ps, other]
arXiv:2609.24723 [pdf, ps, other]
arXiv:2308.00638 [pdf, ps, other]
arXiv:2408.08823 [pdf, ps, other]
arXiv:2509.23490 [pdf, ps, other]
arXiv:2511.22641 [pdf, ps, other]
arXiv:2512.02992 [pdf, ps, other]
arXiv:2601.13473 [pdf, ps, other]
arXiv:2603.00241 [pdf, ps, other]
arXiv:2604.06586 [pdf, ps, other]
arXiv:2604.08321 [pdf, ps, other]
arXiv:2605.11280 [pdf, ps, other]
arXiv:2606.06974 [pdf, ps, other]
arXiv:2606.25425 [pdf, ps, other]
arXiv:2606.29988 [pdf, ps, other]
arXiv:2608.29762 [pdf, ps, other]
arXiv:2609.16138 [pdf, ps, other]
arXiv:2609.22403 [pdf, ps, other]
arXiv:2609.22426 [pdf, ps, other]
arXiv:2609.22428 [pdf, ps, other]
arXiv:2609.22507 [pdf, ps, other]
arXiv:2609.22559 [pdf, ps, other]
arXiv:2609.22577 [pdf, ps, other]
arXiv:2609.22627 [pdf, ps, other]
arXiv:2609.22751 [pdf, ps, other]
arXiv:2609.22811 [pdf, ps, other]
arXiv:2609.22874 [pdf, ps, other]
arXiv:2609.23177 [pdf, ps, other]
arXiv:2609.23259 [pdf, ps, other]
arXiv:2609.23480 [pdf, ps, other]
arXiv:2609.23689 [pdf, ps, other]
arXiv:2609.23791 [pdf, ps, other]
arXiv:2609.23846 [pdf, ps, other]
arXiv:2609.23982 [pdf, ps, other]
arXiv:2609.24085 [pdf, ps, other]
arXiv:2609.24256 [pdf, ps, other]
arXiv:2609.24286 [pdf, ps, other]
arXiv:2609.24387 [pdf, ps, other]
arXiv:2609.24495 [pdf, ps, other]