Current date: 2026-08-25

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Datestamp limit: 2026-08-25 (0 days ago)

Created/updated limit: 2026-08-18 (7 days ago)

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OAI-PMH request: http://export.arxiv.org/oai2?verb=ListRecords&from=2026-08-25&until=2026-08-25&set=physics&metadataPrefix=arXiv

Scoring abstracts

Number of records retrieved: 1146

Keyword score statistics

score 12 -- 1 abstracts

score 7 -- 4 abstracts

score 6 -- 2 abstracts

score 5 -- 2 abstracts

score 4 -- 5 abstracts

score 3 -- 13 abstracts

score 2 -- 20 abstracts

in total -- 47 abstracts

Articles that appeared on 2026-08-25

[abstract 1 / 47] Wow! (score: 12)
arXiv:2608.22051 [pdf, ps, other]

Title: Particle acceleration and non-thermal broadband spectrum of extended shocked outflows in BLACK HOLE binary V4641 Sgr - a galactic pevatron

Authors: Andrei Bykov, Sergei Osipov, Vadim Romansky, Eugene Churazov, Ildar Khabibullin,

Comments: 17 pages, 13 figures, in press

Subjects: astro-ph.HE astro-ph.GA astro-ph.SR

Created: 2026-08-22; Updated: 2026-08-25; Datestamp: 2026-08-25

Stellar mass BLACK HOLEs accreting at a super-Eddington rate produce strong outflows and non-thermal radiation up to PeV energy. Recently, very high energy (VHE) emission was discovered from the environment of the galactic microQUASAR V4641 Sgr, which is known to experience super-Eddington outbursts. We present MHD simulations supplemented with a nonlinear kinetic Monte Carlo model that reproduces the observed radio, X-ray, and gamma-ray emission from the region over tens of parsecs surrounding V4641 Sgr. The reported multi-wavelength non-thermal emission can be explained as produced by PeV electrons accelerated by a system of strong shock waves created by the interaction between a narrow trans-RELATIVISTIC polar JET and a quasi-spherical accretion-disk wind. The shock positions are associated with bright spots of the gamma-ray and X-ray radiation, whose spatial profiles can be tested with dedicated observations. The model predicts that a sizable fraction of the JET's kinetic energy is channeled into TeV-PeV protons, suggesting that such systems might be powerful sources of PeV-range COSMIC RAYs during the accelerator activity cycle. In this model, the bow-tie shape structure discovered by MeerKAT in V4641 Sgr is associated with the radio emission from the termination surface of the quasi-spherical accretion-disk wind. The newly presented (from the SRG/eROSITA all-sky survey) and archival (INTEGRAL and SWIFT BAT) X-ray data are quantitatively consistent with the model, and simultaneously reproduce VHE measurements with H.E.S.S., HAWC, and LHAASO. Deeper X-ray observations will provide a test of the intermittent operation of the accelerator, in contrast with more persistent sources such as SS433/W50.

[abstract 2 / 47] Wow! (score: 7)
arXiv:2608.21576 [pdf, ps, other]

Title: Relativistic blob signatures in the M87 JET at sub-parsec scales

Authors: Donaldo Mora, Alejandro Cruz-Osorio, Erika Benítez, Yosuke Mizuno,

Comments: 7 pages, 4 figures

Subjects: astro-ph.HE

Created: 2026-08-21; Updated: 2026-08-25; Datestamp: 2026-08-25

In this work, we present results from general-RELATIVISTIC radiative-transfer calculations of BLACK HOLE accretion and JET launching to reproduce the observed properties of the M\,87 JET at sub-parsec scales. For the first time, in the simulations we have included a blob component at the launching region of the JET that allowed us to reproduce the quasi-simultaneous low-energy spectral energy distribution ($10^{10} \text{ Hz} \leq ν\leq 10^{16} \text{ Hz}$). Moreover, we obtain a better fit of the SYNCHROTRON emission in the self-absorption region ($ν\leq 10^{11} \text{ Hz}$), showing that the inclusion of a blob component in our radiative transfer calculations results in a flatter spectrum ($α_{22-86\ \text{GHz}}=0.08$). Additionally, our simulations improved the accuracy of the observed morphology of M\,87's JET, matching the data up to a distance of 0.6 mas from the core at 86 GHz. Our results reproduce the edge-brightened structure up to $\sim1.3$ mas, i.e., in a more extended region compared with previous studies, with a brighter southern edge. The obtained synthetic image of the JET reproduces additional observed knots along the southern edge.

[abstract 3 / 47] Wow! (score: 7)
arXiv:2608.22046 [pdf, ps, other]

Title: Correlation of gamma-ray and optical variability of BL~Lacertae during the period of high BLAZAR activity

Authors: Marina S. Butuzova, Mark A. Gorbachev,

Comments: 14 pages, 11 figures, 2 tables

Subjects: astro-ph.HE

Created: 2026-08-22; Updated: 2026-08-25; Datestamp: 2026-08-25

Investigating the correlation of flux variability in BLAZARs across multiple spectral bands provides a key tool for constraining emission mechanisms and JET physical parameters. We study the gamma-ray and optical variability correlation of BL Lacertae on timescales of about 1 day during September 2022, when the source was within the TESS field of view, and over a longer period (April 2022 - September 2023) encompassing its gamma-ray flare, which finishes the series of flares during the high-activity phase. Our analysis confirms the Synchrotron Self-Compton mechanism as the origin of the gamma-ray emission, characterized by a zero time lag. For the longer interval, the Discrete Correlation Function (DCF) reveals a second statistically significant peak at the time lag of about 12 days. We demonstrate that this peak arises due to the presence of an additional flare in one of the bands, which accompanies a gamma-ray and optical flares correlated at zero time lag. We interpret the orphan flare origin in terms of the propagation of an injected blob of high-energy electrons along a JET with a decaying MAGNETic field, accounting for electron radiative cooling.

[abstract 4 / 47] Wow! (score: 7)
arXiv:2608.23310 [pdf, ps, other]

Title: Binary Neutron Star Merger Simulations with Microphysical Equation of State using Spritz

Authors: Fatemeh Hossein Nouri, Jay V. Kalinani, Bruno Giacomazzo, Riccardo Ciolfi, Albino Perego,

Comments:

Subjects: astro-ph.HE gr-qc

Created: 2026-08-24; Updated: 2026-08-25; Datestamp: 2026-08-25

We present the first binary neutron star merger simulations performed with the general-RELATIVISTIC MAGNETohydrodynamics (GRMHD) Spritz code employing a finite-temperature tabulated equation of state. Two MAGNETized binaries with the LS220 equation of state and a GW170817-like chirp mass, differing only in their mass ratios ($q=1$ and $q=0.7$), are evolved from the late inspiral through merger, hypermassive neutron-star (HMNS) formation, and delayed collapse to a BLACK HOLE (BH). We investigate how the binary mass ratio influences the postmerger evolution, JET-launching conditions, and matter ejection. We find that the equal-mass binary forms a slightly longer-lived HMNS, allowing more efficient MAGNETic-field amplification during the post-merger evolution. As a result, it accumulates larger MAGNETic fluxes, develops a MAGNETically dominated funnel, and launches a collimated MAGNETically driven polar outflow. In contrast, the unequal-mass binary ejects approximately 50% more mass but exhibits weaker MAGNETic-field amplification, with the polar region remaining turbulent and baryon loaded throughout our simulation, suggesting that the development of a MAGNETically dominated funnel is likely delayed.

[abstract 5 / 47] Wow! (score: 7)
arXiv:2608.23477 [pdf, ps, other]

Title: Updated Upper Limits on the Isotropic Gravitational-Wave Background from LIGO, Virgo, and KAGRA Data through April 2025

Authors: The LIGO Scientific Collaboration, the Virgo Collaboration, the KAGRA Collaboration, A. G. Abac, A. Abe, I. Abouelfettouh, F. Acernese, K. Ackley, A. Adam, C. Adamcewicz, S. Adhicary, D. Adhikari, R. X. Adhikari, V. K. Adkins, S. Afroz, A. Agapito, D. Agarwal, M. Agathos, N. Aggarwal, S. Aggarwal, O. D. Aguiar, I. -L. Ahrend, L. Aiello, A. Ain, P. Ajith, T. Akutsu, L. Albers, W. Ali, S. Al-Kershi, C. Allene, A. Allocca, S. Al-Shammari, J. A. Alvarez, S. Alvarez-Lopez, W. Amar, O. Amarasinghe, A. Amato, F. Amicucci, C. Amra, A. B. Anand, C. Anand, A. Ananyeva, S. B. Anderson, W. G. Anderson, M. Andia, M. Ando, F. Andrade-Oliveira, M. Andrés-Carcasona, J. L. Andrey, T. Andrić, J. Anglin, J. Anna, J. M. Antelis, S. Antier, T. Aoki, M. Aoumi, E. Z. Appavuravther, E. A. Appelt, S. Appert, S. K. Apple, K. Arai, A. Araya, M. C. Araya, F. Arciprete, J. S. Areeda, N. Aritomi, F. Armato, S. Armstrong, N. Arnaud, M. Arogeti, S. M. Aronson, G. Ashton, Y. Aso, L. Asprea, M. Assiduo, S. Assis de Souza Melo, S. M. Aston, P. Astone, P. S. Aswathi, F. Attadio, F. Aubin, K. AultONeal, G. Avallone, N. Avdeev, E. A. Avila, S. Babak, C. Badger, S. Bae, S. Bagnasco, S. Baimukhametova, L. Baiotti, T. Baka, K. A. Baker, T. Baker, G. Balbi, G. Baldi, N. Baldicchi, M. Ball, G. Ballardin, M. Ballelli, S. W. Ballmer, S. Banagiri, B. Banerjee, D. Bankar, T. M. Baptiste, P. Baral, M. Baratti, J. C. Barayoga, K. Baric, B. C. Barish, D. Barker, N. Barman, F. Barone, B. Barr, M. Barrios, L. Barsotti, M. Barsuglia, D. Barta, M. A. Barton, I. Bartos, A. Basalaev, R. Bassiri, A. Basti, M. Bawaj, J. C. Bayley, A. C. Baylor, P. A. Baynard, M. Bazzan, V. M. Bedakihale, F. Beirnaert, M. Bejger, A. S. Bell, C. Bellani, D. S. Bellie, D. Beltran-Martinez, E. Benedetti, W. Benoit, I. Bentara, M. Ben Yaala, S. Bera, F. Bergamin, B. K. Berger, M. Beroiz, I. Berry, D. Bersanetti, T. Bertheas, A. Bertolini, J. Betzwieser, D. Beveridge, N. Bevins, J. Bezerra-Sobrinho, R. Bhandare, R. Bhatt, A. Bhattacharjee, D. Bhattacharjee, S. Bhattacharyya, S. Bhaumik, V. Biancalana, F. Bianchi, I. A. Bilenko, M. Bilicki, G. Billingsley, A. Binetti, S. Bini, S. Biot, O. Birnholtz, S. Biscoveanu, A. Bisht, M. Bitossi, M. -A. Bizouard, S. Blaber, J. K. Blackburn, L. A. Blagg, C. D. Blair, D. G. Blair, M. Bloch, N. Bode, N. Boettner, P. Bogdan, G. Boileau, M. Boldrini, G. N. Bolingbroke, L. D. Bonavena, V. A. Bonhomme, E. Bonilla, M. S. Bonilla, A. Bonino, R. Bonnand, A. Borchers, N. Borghi, V. Boschi, S. Bose, V. Bossilkov, Y. Bothra, A. Boudon, T. D. Boybeyi, M. Boyle, A. Bozzi, C. Bradaschia, M. J. Brady, P. R. Brady, A. Branch, M. Branchesi, T. Briant, A. Brillet, M. Brinkmann, P. Brockill, E. Brockmueller, A. F. Brooks, D. D. Brown, M. L. Brozzetti, S. Brunett, G. Bruno, R. Bruntz, J. Bryant, Y. Bu, F. Bucci, A. Buchicchio, A. Buggiani, O. Bulashenko, T. Bulik, H. J. Bulten, A. Buonanno, K. Burtnyk, R. Buscicchio, N. Busdon, D. Buskulic, R. L. Byer, R. Cabrita, V. A. Cáceres-Barbosa, L. Cadonati, G. Cagnoli, C. Cahillane, A. Calafat, J. Calderón Bustillo, J. D. Callaghan, T. A. Callister, E. Calloni, S. R. Callos, K. Cannon, V. Cantory, H. Cao, L. A. Capistran, E. Capocasa, G. Capoccia, E. Capote, C. Capuano, G. Capurri, F. Carbognani, K. J. Cardona-Martínez, M. Carlassara, M. Carpinelli, G. Carrillo, G. Carullo, A. Casallas-Lagos, J. Casanueva Diaz, C. Casentini, S. Caudill, M. Cavaglià, R. Cavalieri, A. Ceja, G. Cella, P. Cerdá-Durán, E. Cesarini, N. Chabbra, W. Chaibi, A. Chakraborty, P. Chakraborty, S. Chakraborty, S. Chalathadka Subrahmanya, C. Chan, J. C. L. Chan, M. Chan, C. -Y. Chang, K. Chang, S. Chao, P. Charlton, E. Chassande-Mottin, C. Chatterjee, Debarati Chatterjee, Deep Chatterjee, M. Chaturvedi, S. Chaty, A. Chen, A. H. -Y. Chen, D. Chen, H. Chen, H. Y. Chen, S. Chen, Yanbei Chen, Yiwen Chen, G. Cheng, H. P. Cheng, P. Chessa, T. Cheunchitra, H. T. Cheung, S. Y. Cheung, F. Chiadini, G. Chiarini, A. Chiba, A. Chincarini, D. Chintala, A. Chiummo, A. Chopra, C. Chou, S. Choudhary, N. Christensen, Y. K. Chu, S. S. Y. Chua, G. Ciani, P. Ciecielag, M. Cieślar, M. Cifaldi, B. Cirok, F. Clara, J. A. Clark, T. A. Clarke, A. Claveus, M. R. Claypool, S. Clesse, F. Cleva, S. M. Clyne, E. Coccia, E. Codazzo, P. -F. Cohadon, D. E. Cohen, E. Colangeli, O. Cole, M. Colleoni, C. G. Collette, J. Collins, S. Colloms, A. Colombo, G. Compère, C. M. Compton, G. Connolly, L. Conti, T. R. Corbitt, I. Cordero-Carrión, S. Corezzi, N. J. Cornish, A. Corsi, S. Cortese, L. A. Corubolo, L. Cotnoir, R. Cottingham, J. A. Cotturone, M. W. Coughlin, P. Couvares, R. Coyne, A. Cozzumbo, J. D. E. Creighton, T. D. Creighton, S. Crook, R. Crouch, J. Csizmazia, K. Csukás, T. J. Cullen, A. Cumming, E. Cuoco, M. Cusinato, R. R. Cuzinatto, L. V. da Conceição, T. Dal Canton, S. Dall'Osso, S. Dal Pra, G. Dálya, Y. Dang, B. D'Angelo, S. Danilishin, O. Danner, S. D'Antonio, K. Danzmann, K. E. Darroch, L. P. Dartez, R. Das, S. Das, A. Dasgupta, V. Dattilo, A. Daumas, I. Dave, A. Davenport, T. F. Davies, D. Davis, M. C. Davis, P. Davis, E. J. Daw, M. Dax, J. De Bolle, E. deBruin, M. Deenadayalan, J. Degallaix, M. De Laurentis, C. J. Delgado Mendez, F. De Lillo, S. Della Torre, W. Del Pozzo, O. M. del Rio, A. Demagny, F. De Marco, G. Demasi, F. De Matteis, C. de Melo, N. Demos, T. Dent, A. Depasse, N. DePergola, R. De Pietri, R. De Rosa, C. De Rossi, E. K. Derrick, M. Desai, D. DeSantis, S. Deshmukh, V. Deshmukh, R. De Simone, S. Determan, S. Dhage, A. Dhani, R. Dhatri, R. Dhurkunde, R. Diab, C. Diaz, M. C. Díaz, F. Diaz Guerra, M. Di Cesare, M. A. Dicorato, T. Dietrich, C. Di Fronzo, M. Di Giovanni, D. Diksha, J. Ding, S. Di Pace, I. Di Palma, D. Di Piero, F. Di Renzo, Divyajyoti, A. Dmitriev, J. P. Docherty, Z. Doctor, N. Doerksen, E. Dohmen, A. Doke, A. Domiciano De Souza, L. D'Onofrio, F. Donovan, K. L. Dooley, S. Doravari, O. Dorosh, F. Dosopoulou, M. Drago, J. C. Driggers, M. Dubois, R. S. Dumbreck, U. Dupletsa, D. D'Urso, P. Dutta Roy, H. Duval, S. Dwivedi, S. E. Dwyer, C. Eassa, M. Eberhardt, M. Ebersold, M. Ebiri, G. Eddolls, A. Effler, J. Eichholz, H. Einsle, M. Eisenmann, M. Emma, K. Endo, R. Enficiaud, V. Ernst, L. Errico, R. Espinosa, M. Esposito, R. C. Essick, H. Estellés, T. Etzel, M. Evans, T. Evstafyeva, J. M. Ezquiaga, F. Fabrizi, V. Fafone, S. Fairhurst, X. Fan, A. M. Farah, B. Farr, W. M. Farr, M. Favata, M. Fays, M. Fazio, J. Feicht, M. M. Fejer, J. -N. Feldhusen, E. Fenyvesi, A. Feo, J. Fernandes, T. Fernandes, G. Fernández Rodríguez, D. Fernando, S. Ferraiuolo, T. A. Ferreira, M. Ferrer-Martinez, F. Fidecaro, P. Figura, I. Fiori, M. Fishbach, R. P. Fisher, S. K. Fitzgerald, V. Fiumara, R. Flaminio, E. Flanagan, S. M. Fleischer, L. S. Fleming, F. Flocco, E. Floden, H. Fong, J. A. Font, F. Fontinele-Nunes, C. Foo, B. Fornal, P. W. F. Forsyth, A. Fragkos, N. Franchini, A. Franco-Ordovas, F. Frappez, F. Frasconi, J. P. Freed, Z. Frei, A. Freise, O. Freitas, R. Frey, W. Frischhertz, P. Fritschel, V. V. Frolov, M. Fuentes-Garcia, R. Fujii, T. Fujimori, Y. Fujiwara, P. Fulda, M. Fyffe, J. R. Gair, S. Galaudage, V. Galdi, M. Galimberti, A. Gamboa, S. Gamoji, A. Ganguly, B. Garaventa, P. García Abia, J. García-Bellido, C. García-Quirós, J. W. Gardner, S. Garg, J. Gargiulo, X. Garrido, A. Garron, F. Garufi, P. A. Garver, C. Gasbarra, F. Gautier, V. Gayathri, T. Gayer, G. Gemme, A. Gennai, V. Gennari, J. George, R. George, O. Gerberding, L. Gergely, A. Ghinassi, Archisman Ghosh, Sayantan Ghosh, Shaon Ghosh, Shrobana Ghosh, Suprovo Ghosh, Tathagata Ghosh, J. A. Giaime, K. D. Giardina, D. R. Gibson, C. Gier, F. Gittins, J. Glanzer, F. Glotin, E. Glowacki, J. Godfrey, R. V. Godley, O. Godwin, A. S. Goettel, E. Goetz, J. Golomb, S. Gomez Lopez, G. González, P. Goodarzi, S. R. Goode, A. Goodwin-Jones, M. Gosselin, S. M. Goss-Grubbs, C. Gostiaux, R. Gouaty, D. W. Gould, D. Goupilliere, K. Govorkova, A. Grado, V. Graham, A. E. Granados, M. Granata, V. Granata, S. Gras, P. Grassia, C. Gray, R. Gray, G. Greco, A. C. Green, L. Green, S. R. Green, A. M. Gretarsson, E. M. Gretarsson, D. Griffith, C. Grimaud, H. Grote, S. Grunewald, A. G. Guerrero, G. M. Guidi, T. Guidry, H. K. Gulati, F. Gulminelli, H. Guo, W. Guo, Y. Guo, A. Gupta, I. Gupta, N. C. Gupta, S. K. Gupta, V. Gupta, N. Gupte, N. Guttman, F. Guzman, M. Haberland, S. Haino, E. D. Hall, E. Z. Hamilton, G. Hammond, W. -B. Han, M. Haney, J. Hanks, C. Hanna, M. D. Hannam, O. A. Hannuksela, H. Hansen, J. Hanson, R. Harada, A. R. Hardison, S. Harikumar, K. Haris, I. Harley-Trochimczyk, J. Harms, G. M. Harry, I. W. Harry, M. T. Hartman, B. Haskell, C. -J. Haster, K. Haughian, H. Hayakawa, K. Hayama, J. Hedberg, A. Heffernan, D. Hegde, M. C. Heintze, J. Heinzel, H. Heitmann, F. Hellman, A. F. Helmling-Cornell, G. Hemming, O. Henderson-Sapir, M. Hendry, I. S. Heng, M. H. Hennig, C. Henshaw, A. Heranval, M. Heurs, A. L. Hewitt, J. Heynen, J. Heyns, S. Hido, S. Hild, M. Hill, S. Hill, Y. Himemoto, C. Hirose, D. Hofman, N. A. Holland, K. Holley-Bockelmann, I. J. Hollows, D. E. Holz, L. Honet, K. M. Hoops, M. E. Hoque, D. J. Horton-Bailey, J. Hough, S. Hourihane, N. T. Howard, E. J. Howell, C. G. Hoy, P. Hsi, H. -Y. Hsieh, C. Hsiung, S. -H. Hsu, W. -F. Hsu, H. Y. Huang, Y. Huang, A. D. Huddart, B. Hughey, D. C. Y. Hui, S. Husa, L. Iampieri, G. A. Iandolo, M. Ianni, Y. Ichinose, K. Ide, R. Iden, A. Ierardi, S. Ikeda, H. Imafuku, K. Imai, Y. Inoue, P. Iosif, J. Irwin, K. Ishida, R. Ishikawa, T. Ishikawa, H. Ishino, M. Isi, K. S. Isleif, Y. Itoh, S. Iwaguchi, M. M. Iwaya, B. R. Iyer, C. Jacquet, T. Jacquot, S. J. Jadhav, S. P. Jadhav, K. Jain, A. L. James, K. Jani, S. Jani, J. Janquart, N. N. Janthalur, S. Jaraba, P. Jaranowski, R. Jaume, W. Javed, M. Jensen, W. Jia, J. Jiang, H. -B. Jin, S. -J. Jin, G. R. Johns, N. A. Johnson, M. C. Johnston, R. Johnston, N. Johny, D. H. Jones, D. I. Jones, R. Jones, P. Joshi, S. K. Joshi, G. Joubert, J. Ju, L. Ju, I. L. Juarez-Reyes, K. Jung, H. B. Kabagoz, B. Kacskovics, T. Kajita, I. Kaku, V. Kalogera, M. Kalomenopoulos, M. Kamiizumi, N. Kanda, S. Kandhasamy, G. Kang, J. B. Kanner, S. J. Kapadia, D. P. Kapasi, A. Karia, A. S. Karia, R. Kashyap, M. Kasprzack, H. Kato, T. Kato, E. Katsavounidis, W. Katzman, R. Kaushik, K. Kawabe, S. Kawamura, D. Keitel, S. A. Kemper, L. J. Kemperman, J. Kennington, R. Kesharwani, J. S. Key, R. Khadela, S. S. Khadkikar, F. Y. Khalili, C. Khamar, F. Khan, M. Khursheed, N. M. Khusid, W. Kiendrebeogo, C. Kim, G. Kim, J. C. Kim, K. Kim, M. H. Kim, S. Kim, Y. -M. Kim, C. Kimball, K. Kimes, M. Kinnear, J. S. Kissel, S. Klimenko, A. M. Knee, N. Knust, K. Kobayashi, S. M. Koehlenbeck, K. Kohri, K. Kokeyama, S. Koley, P. Kolitsidou, A. E. Koloniari, K. Komori, K. Kompanets, A. K. H. Kong, A. Kontos, K. Kopczuk, L. M. Koponen, M. Korobko, X. Kou, N. Kouvatsos, T. Koyama, D. B. Kozak, E. Kraja, S. L. Kranzhoff, V. Kringel, N. V. Krishnendu, S. Kroker, A. Królak, K. Kruska, J. Kubisz, K. Kubota, G. Kuehn, D. Kukla, A. Kulur Ramamohan, Achal Kumar, Anil Kumar, Dhruv Kumar, Praveen Kumar, Prayush Kumar, Rahul Kumar, Rakesh Kumar, Ravi Kumar, J. Kume, K. Kuns, N. Kuntimaddi, S. Kuroyanagi, K. Kwak, K. Kwan, S. Kwon, G. Lacaille, D. Laghi, A. H. Laity, N. Lajili, A. Lakhal, E. Lalande, M. Lalleman, S. Lalvani, M. Landry, R. N. Lang, A. Lange, J. A. Lange, R. Langgin, B. Lantz, I. La Rosa, O. Laske, P. D. Lasky, L. Lavezzi, J. Lawrence, M. Laxen, A. Lazzarini, C. Lazzaro, P. Leaci, L. Leali, Y. K. Lecoeuche, H. W. Lee, J. Lee, K. Lee, R. -K. Lee, R. Lee, Sungho Lee, Sunjae Lee, W. Lee, Y. Lee, F. Legger, I. N. Legred, J. Lehmann, L. Lehner, M. Le Jean, A. Lema{î}tre, R. Lemrani Alaoui, M. Lenti, M. Leonardi, M. Lequime, M. Lesovsky, N. Letendre, M. Lethuillier, Y. Levin, S. Lexmond, K. Leyde, A. K. Y. Li, K. L. Li, T. G. F. Li, X. Li, Y. Li, Z. Li, Q. Liang, C-Y. Lin, E. T. Lin, F. Lin, L. C. -C. Lin, Y. -C. Lin, C. Lindsay, S. D. Linker, A. Liu, F. Liu, G. C. Liu, Jian Liu, S. Liu, F. Llamas Villarreal, J. Llobera-Querol, R. K. L. Lo, J. -P. Locquet, S. C. G. Loggins, L. T. London, A. Longo, M. Lopez Portilla, A. Lorenzo-Medina, V. Loriette, M. Lormand, M. Lorusso, G. Losurdo, T. P. Lott, J. D. Lough, H. A. Loughlin, C. O. Lousto, N. K. Y. Low, N. Lu, H. Lück, O. Lukina, D. Lumaca, A. P. Lundgren, L. Lunghini, A. W. Lussier, L. -T. Ma, X. Ma, M. Ma'arif, S. MacBride, K. Machida, D. M. Macleod, I. A. O. MacMillan, A. Macquet, S. S. Madekar, S. Maenaut, S. S. Magare, R. M. Magee, E. Maggio, M. Magnozzi, P. Mahapatra, M. Mahesh, S. Majhi, E. Majorana, C. N. Makarem, E. Makelele, N. Malagon, D. Malakar, J. A. Malaquias-Reis, U. Mali, S. Maliakal, A. Malik, L. Mallick, A. -K. Malz, N. Man, M. Mancarella, V. Mandic, V. Mangano, Z. Mangi, B. Mannix, G. L. Mansell, M. Manske, M. Mantovani, M. Mapelli, S. Marchetti, F. Marion, J. Mark, A. S. Markosyan, J. Markus, E. Maros, S. Marsat, F. Martelli, I. W. Martin, R. M. Martin, B. B. Martinez, M. Martinez, V. Martinez, A. Martini, Juan Carlos Martins, Julio C. Martins, D. V. Martynov, E. J. Marx, L. Massaro, A. Masserot, M. Masso-Reid, T. Masters, S. Mastrogiovanni, G. Mastropasqua, M. Matiushechkina, A. Matte-Landry, L. Maurin, N. Mavalvala, N. Maxwell, A. McCann, G. McCarrol, R. McCarthy, D. E. McClelland, S. McCormick, L. McCuller, L. I. McDermott, C. McElhenny, G. I. McGhee, K. B. M. McGowan, J. McIver, A. McLeod, I. McMahon, T. McRae, R. McTeague, K. McWhirter, D. Meacher, B. N. Meagher, R. Mechum, L. G. Medeiros, R. M. Mehta, A. Melatos, C. S. Menoni, R. A. Mercer, L. Mereni, K. Merfeld, E. L. Merilh, J. R. Mérou, C. Messick, M. Meyer-Conde, F. Meylahn, H. Miao, C. Michel, Y. Michimura, H. Middleton, D. P. Mihaylov, S. J. Miller, M. Millhouse, E. Milotti, V. Milotti, E. Minakaki, Y. Minenkov, Ll. M. Mir, L. Mirasola, C. -A. Miritescu, A. Mishra, C. Mishra, T. Mishra, A. Mitchell, J. G. Mitchell, O. Mitchem, S. Mitra, V. P. Mitrofanov, K. Mitsuhashi, R. Mittleman, O. Miyakawa, S. Miyoki, G. Mo, L. Mobilia, S. R. P. Mohapatra, M. Molina-Ruiz, M. Mondin, M. Montani, G. Montefusco, C. J. Moore, D. Moraru, A. More, S. More, C. Moreno, E. A. Moreno, G. Moreno, A. Moreso Serra, C. Morgan, S. Morisaki, S. Moriwaki, Y. Moriwaki, G. Morras, A. Moscatello, M. Mould, B. Mours, C. M. Mow-Lowry, L. Muccillo, F. Muciaccia, Arunava Mukherjee, D. Mukherjee, Samanwaya Mukherjee, Soma Mukherjee, Subroto Mukherjee, Suvodip Mukherjee, N. Mukund, A. Mullavey, C. L. Mungioli, Y. Murakami, M. Murakoshi, P. G. Murray, D. Nabari, S. Nadji, A. Nagar, N. Nagarajan, K. Nakagaki, A. Nakamura, K. Nakamura, H. Nakano, M. Nakano, D. Nanadoumgar-Lacroze, D. Nandi, V. Napolano, S. U. Naqvi, P. Narayan, A. Nardecchia, I. Nardecchia, T. Narikawa, H. Narola, L. Naticchioni, R. K. Nayak, J. Neeson, L. Negri, A. Nela, C. Nelle, A. Nelson, T. J. N. Nelson, A. Nemmani, A. Neunzert, M. Newell, S. Ng, T. C. K. Ng, L. -A. T. Nguyen, T. T. Nguyen, L. Nguyen Quynh, A. B. Nielsen, Y. Nishino, A. Nishizawa, S. Nissanke, W. Niu, F. Nocera, J. Noller, M. Norman, C. North, J. Novak, G. Nurbek, L. K. Nuttall, K. Obayashi, J. Oberling, C. E. Ochoa, C. O'Connor, J. O'Dell, E. Oelker, M. Oertel, G. Oganesyan, J. J. Oh, T. O'Hanlon, M. Ohashi, F. Ohme, Y. Okabe, I. Oke, R. Oliveira, R. Omer, N. O'Neill, M. Onishi, K. Oohara, P. Ophardt, R. J. Oram, B. O'Reilly, R. O'Shaughnessy, S. Oshino, J. Ostrovska, A. Osumi, I. Ota, G. Othman, M. Otsuka, D. J. Ottaway, A. Ouzriat, H. Overmier, B. J. Owen, A. E. Pace, M. A. Page, A. Pai, S. Pal, M. A. Palaia, M. Pálfi, C. Palomba, H. Pan, J. Pan, K. -C. Pan, P. K. Panda, Shiksha Pandey, Swadha Pandey, P. T. H. Pang, F. Pannarale, B. C. Pant, F. H. Panther, M. Panzeri, F. Paoletti, A. Paoli, A. Paolone, A. Papadopoulos, E. E. Papalexakis, L. Papalini, G. Papigkiotis, A. Paquis, A. Parisi, B. -J. Park, Jihwan Park, Junegyu Park, W. Parker, G. Pascale, D. Pascucci, A. Pasqualetti, L. Passenger, D. Passuello, O. Patane, A. V. Patel, L. Pathak, A. Patra, B. Patricelli, B. G. Patterson, K. Paul, S. Paul, E. Payne, T. Pearce, M. Pedraza, A. Pele, F. E. Peña Arellano, X. Peng, Y. Peng, S. Penn, A. Perreca, J. Perret, D. Pesios, S. Petracca, C. Petrillo, H. P. Pfeiffer, H. Pham, K. A. Pham, K. S. Phukon, H. Phurailatpam, L. Piccari, O. J. Piccinni, M. Pichot, A. Pied, M. Piendibene, F. Piergiovanni, L. Pierini, G. Pierra, V. Pierro, M. Pillas, B. Pillon, L. Pinard, I. M. Pinto, M. Pinto, B. J. Piotrzkowski, M. Pirello, A. Pisarski, M. D. Pitkin, E. Placidi, M. L. Planas, C. Plunkett, R. Poggiani, E. Polini, M. Polo, J. Pomper, L. Pompili, J. Poon, E. Porcelli, A. S. Porter, E. K. Porter, C. Posnansky, J. Powell, G. S. Prabhu, M. Pracchia, A. K. Prajapati, K. Prasai, R. Prasanna, P. Prasia, G. Pratten, G. Principe, G. A. Prodi, P. Prosperi, P. Prosposito, A. Puecher, J. Pullin, M. Punturo, P. Puppo, M. Pürrer, H. Qi, M. Qiao, J. Qin, G. Quéméner, V. Quetschke, P. J. Quinonez, R. Rading, I. Rainho, S. Raja, C. Rajan, B. Rajbhandari, M. R. Raj Sah, K. E. Ramirez, F. A. Ramis Vidal, M. Ramos Arevalo, A. Ramos-Buades, S. Ranjan, M. Ranjbar, K. Ransom, R. Rao, P. Rapagnani, B. Ratto, A. Ravichandran, A. Ray, V. Raymond, M. Razzano, J. Read, J. Redepenning, J. Regan, T. Regimbau, T. Reichardt, S. Reid, C. Reissel, D. H. Reitze, A. I. Renzini, B. Revenu, A. Revilla-Peña, F. Ricci, M. Ricci, A. Ricciardone, J. Rice, J. W. Richardson, M. L. Richardson, K. Riles, H. K. Riley, A. Riminucci, F. Robinet, M. Robinson, A. Rocchi, J. Rodriguez, R. Rodriguez Lopez, L. Rolland, J. G. Rollins, A. E. Romano, R. Romano, A. Romero-Rodríguez, I. M. Romero-Shaw, J. H. Romie, S. Ronchini, T. J. Roocke, T. J. Rosauer, C. A. Rose, D. Rosińska, M. P. Ross, M. Rossello-Sastre, S. Rowan, K. Rowlands, S. K. Roy, S. Roy, T. RoyChowdhury, D. Rozza, P. Ruggi, G. H. Ruiz, E. Ruiz Morales, K. Ruiz-Rocha, V. Russ, S. M. S, S. Sachdev, T. Sadecki, F. Safai Tehrani, P. Saffarieh, S. Safi-Harb, S. Saha, T. Sainrat, S. Sajith Menon, K. Sakai, Y. Sakai, M. Sakellariadou, S. Sakon, F. Salces-Carcoba, L. Salconi, M. Saleem, F. Salemi, M. Sallé, M. Salomé, S. U. Salunkhe, S. Salvador, A. Salvarese, A. Samajdar, P. M. Samir, A. Sanchez, E. J. Sanchez, J. Sanchez, D. Sanchez-Cid, N. Sanchis-Gual, J. R. Sanders, E. M. Sänger, F. Santoliquido, E. Sapkin, F. Sarandrea, T. R. Saravanan, P. Sarkar, A. Sasli, P. Sassi, B. Sassolas, O. Sauter, R. L. Savage, T. Savicheva, T. Sawada, H. L. Sawant, D. Schaetzl, M. Scheel, A. Schiebelbein, M. G. Schiworski, K. Schluterman, P. Schmidt, R. Schnabel, M. Schneewind, R. M. S. Schofield, M. Schoor, K. Schouteden, B. W. Schulte, M. Schulz, B. F. Schutz, E. Schwartz, M. Scialpi, J. Scott, S. M. Scott, R. M. Sedas, T. C. Seetharamu, M. Seglar-Arroyo, Y. Sekiguchi, D. Sellers, N. Sembo, E. G. Seo, J. W. Seo, G. Seong, V. Sequino, M. Serra, C. K. Sethi, A. Sevrin, T. Shaffer, U. S. Shah, M. A. Shaikh, L. Shao, J. Sharkey, A. K. Sharma, Preeti Sharma, Priyanka Sharma, Sushant Sharma-Chaudhary, P. Shawhan, T. Shen, Z. -H. Shi, K. Shimode, H. Shinkai, S. Shirke, D. H. Shoemaker, D. M. Shoemaker, R. W. Short, S. ShyamSundar, H. Siegel, V. Sierra, D. Sigg, L. Silenzi, P. J. S. Silva, L. Silvestri, M. Simmonds, L. P. Singer, A. Singh, D. Singh, M. K. Singh, N. Singh, S. Singh, M. R. Sinha, A. M. Sintes, V. Skliris, B. J. J. Slagmolen, T. J. Slaven-Blair, J. Smetana, D. A. Smith, J. R. Smith, J. Smith, L. Smith, W. J. Smith, S. Soares de Albuquerque Filho, M. Soares-Santos, K. Somiya, I. Song, S. Soni, V. Sordini, F. Sorrentino, H. Sotani, N. E. Sovitzky, F. Spada, V. Spagnuolo, A. P. Spencer, M. Spera, P. Spinicelli, A. K. Srivastava, F. Stachurski, V. V. Stanford, A. Stanton, D. A. Steer, N. Steinle, J. Steinlechner, S. Steinlechner, C. Stephens, N. Stergioulas, M. StPierre, J. Stremiz, M. D. Strong, A. Strunk, M. Suchenek, S. Sudhagar, R. Sugimoto, L. Suleiman, K. D. Sullivan, J. Sun, L. Sun, S. Sunil, J. Suresh, P. J. Sutton, K. Suzuki, M. Suzuki, A. Svizzeretto, B. L. Swinkels, A. Syx, M. J. Szczepańczyk, M. Tacca, M. Tagliazucchi, H. Tagoshi, S. C. Tait, H. Takaba, K. Takada, H. Takahashi, R. Takahashi, A. Takamori, S. Takano, H. Takeda, I. Takimoto Schmiegelow, C. Talbot, M. Tamaki, N. Tamanini, D. Tanabe, K. Tanaka, S. J. Tanaka, S. Tanioka, D. B. Tanner, W. Tanner, L. Tao, R. D. Tapia, E. N. Tapia San Martín, A. Taruya, J. D. Tasson, J. G. Tau, A. Tejera, J. G. Temple, Y. Teng, H. Themann, A. Theodoropoulos, M. P. Thirugnanasambandam, L. M. Thomas, M. Thomas, P. Thomas, J. E. Thompson, S. R. Thondapu, E. Thrane, J. Tissino, A. Tiwari, Pawan Tiwari, Praveer Tiwari, S. Tiwari, V. Tiwari, M. R. Todd, E. Tofani, M. Toffano, A. M. Toivonen, K. Toland, T. Tomaru, V. Tommasini, H. Tong, C. I. Torrie, I. Tosta e Melo, E. Tournefier, A. Trapananti, R. Travaglini, F. Travasso, G. Traylor, L. Traylor, M. Trevor, M. C. Tringali, A. Tripathee, G. Troian, A. Trovato, L. Trozzo, R. J. Trudeau, T. Tsang, S. Tsuchida, K. Tsuji, L. Tsukada, A. Tuci, M. Turconi, C. Turski, H. Ubach, A. S. Ubhi, N. Uchikata, T. Uchiyama, R. P. Udall, T. Uehara, V. Undheim, V. Upadhyaya, L. E. Uronen, T. Ushiba, M. Vacatello, H. Vahlbruch, G. Vajente, J. Valencia, M. Valentini, E. Vallejo-Pagès, S. A. Vallejo-Peña, S. Vallero, M. van Dael, E. Van den Bossche, J. F. J. van den Brand, C. Van Den Broeck, M. van der Kolk, M. van der Sluys, A. Van de Walle, J. van Dongen, K. Vandra, M. VanDyke, H. van Haevermaet, J. V. van Heijningen, P. Van Hove, J. Vanier, J. Vanosky, N. van Remortel, M. Vardaro, A. F. Vargas, V. Varma, A. Vecchio, G. Vedovato, J. Veitch, P. J. Veitch, S. Venikoudis, P. Verdier, M. Vereecken, D. Verkindt, B. Verma, S. Verma, Y. Verma, S. M. Vermeulen, F. Vetrano, A. Veutro, A. Viceré, S. Vidyant, A. D. Viets, A. Vijaykumar, A. Vilkha, N. Villanueva Espinosa, E. T. Vincent, J. -Y. Vinet, S. Viret, S. Vitale, A. Vives, L. Vizmeg, B. Vizzone, H. Vocca, D. Voigt, E. R. G. von Reis, J. S. A. von Wrangel, W. E. Vossius, L. Vujeva, S. P. Vyatchanin, J. Wack, L. E. Wade, M. Wade, K. J. Wagner, L. Wallace, R. -Z. Wan, H. Wang, P. Wang, W. H. Wang, Y. F. Wang, Z. Wang, R. L. Ward, J. Warner, M. Was, T. Washimi, N. Y. Washington, D. Watarai, B. Weaver, S. A. Webster, N. L. Weickhardt, M. Weinert, A. J. Weinstein, R. Weiss, L. Wen, K. Wette, C. Wheeler, J. T. Whelan, B. F. Whiting, E. G. Wickens, D. Wilken, B. M. Williams, D. Williams, M. J. Williams, N. S. Williams, J. L. Willis, B. Willke, M. Wils, L. Wimmer, C. W. Winborn, A. Wingfield, J. Winterflood, C. C. Wipf, G. Woan, N. E. Wolfe, H. T. Wong, I. C. F. Wong, T. Wouters, J. L. Wright, M. Wright, B. Wu, C. Wu, D. S. Wu, H. Wu, K. Wu, Z. Wu, E. Wuchner, D. M. Wysocki, V. A. Xu, Y. Xu, N. Yadav, H. Yamamoto, K. Yamamoto, T. S. Yamamoto, T. Yamamoto, R. Yamazaki, T. Yan, H. Yang, K. Z. Yang, Y. Yang, Z. Yarbrough, J. Yébana Carrilero, A. B. Yelikar, X. Yin, J. Yokoyama, T. Yokozawa, M. Yoshihara, S. Yuan, H. Yuzurihara, M. Zanatta, M. Zanolin, M. Zeeshan, T. Zelenova, J. -P. Zendri, M. Zeoli, M. Zerrad, M. Zevin, H. Zhang, J. Zhang, L. Zhang, N. Zhang, R. Zhang, T. Zhang, C. Zhao, J. Zhao, Yue Zhao, Yuhang Zhao, L. -M. Zheng, Y. Zheng, L. Zhizhong, H. Zhong, H. Zhou, H. O. Zhu, X. -J. Zhu, Z. -H. Zhu, Z. Zhu, D. Z. Zieba, A. B. Zimmerman, L. Zimmermann, M. E. Zucker,

Comments: 26 pages, 6 figures

Subjects: gr-qc astro-ph.CO astro-ph.HE

Created: 2026-08-24; Updated: 2026-08-25; Datestamp: 2026-08-25

We report results from a search for an isotropic stochastic gravitational-wave background using data collected by the LIGO--Virgo--KAGRA Collaboration. The analysis uses data from the first observing run through April 1, 2025, during the fourth observing run. New frequency-domain cuts are implemented to address a class of non-stationary spectral noise features that were not effectively identified and mitigated by existing data-quality checks in past analyses. Consequently, previously analyzed data from the fourth observing run are re-processed with the updated cuts. We find no evidence for a stochastic background signal and place upper limits on the gravitational-wave energy density. In particular, for a background following a power law with spectral index 2/3 as predicted by inspiralling compact binaries, we find $Ω_\mathrm{GW}(25\,\mathrm{Hz}) \leq 2.0 \times 10^{-9}$, while scale-invariant backgrounds are constrained to $Ω_\mathrm{GW}(25\,\mathrm{Hz}) \leq 2.8 \times 10^{-9}$, both at the 95\% credible level for a log-uniform prior on $Ω_\mathrm{GW}$. Relative to the constraints from previous data recomputed with the new frequency-domain cuts, these limits improve by a factor of 1.4. We also update bounds on alternative gravity scenarios predicting non-standard POLARIZATION modes, and we verify that correlated MAGNETic noise sources remain below the sensitivity of this search. Combining these observational constraints with population models of compact binary coalescences informed by the latest gravitational-wave transient catalog, GWTC-5.0, we predict the amplitude of the compact binary background to be $Ω_\mathrm{CBC}(25\,\mathrm{Hz}) = 6.3^{+5.0}_{-2.2} \times 10^{-10}$ at the 90\% credible level.

[abstract 6 / 47] Yes (score: 6)
arXiv:2608.01009 [pdf, ps, other]

Title: Day-timescale Quasi-periodic Oscillations of the Gev BL Lac RX J0805.4+7534 with TESS

Authors: Xin-Shun Jin, Ting-Feng Yi, Yangwei Zhang, Yuncai Shen, Junjie Wang, Lisheng Mao, Liang Dong,

Comments: 13 pages, 4 figures. accepted for publication in RAA

Subjects: astro-ph.HE

Created: 2026-08-24; Updated: 2026-08-25; Datestamp: 2026-08-25

This paper reports for the first time the detection of quasi-periodic oscillations (QPOs) in the light curves of the BL Lacertae object RX J0805.4+7534. The Transiting Exoplanetary Survey Satellite (TESS) observed this source in seven sectors of the sky, and we extracted the light curves for these sectors using a custom method. The presence of QPO signals was found in these light curves. To detecte the periodicity and assess the statistical significance of the QPO signals, we employed two methods: Lomb-Scargle periodograms and Weighted Wavelet \textit{Z}-transform. Both of these different methods yielded consistent results. \textcolor{red}{\sout{The results showed signals with day-timescale QPO in sectors 20, 26, 53, and 73, with confidence levels exceeding $3σ$, and three of the sectors exhibited a ~3.8 days QPO. To explain these rapid quasi-periodic changes, we discuss several possible explanations. We propose that the QPO signal might be due to the rotation of hot spots on circular orbits within the accretion disk.}}\textcolor{blue}{The results show that QPO signals exist in sectors 20, 26, and 53, with the confidence levels exceeding 99.73\%. The QPOs in sectors 20 and 26 are $\sim 3.8$ days and have a global significance of 95\%. To explain these rapid quasi-periodic variations, we discussed several possible physical scenarios. The most possible one is the kink instability in RELATIVISTIC JETs. The other possible scenario is the rotation of hot-spots in the innermost accretion disk. Based on the hot-spot orbital model hypothesis, the mass of the BLACK HOLE at the center of this BL Lac object wes estimated. The validity of these two explanations requires further observational data to verify. However, since the radiation of BL Lac objects primarily originates from JETs, we prefer the kink instability in RELATIVISTIC JETs to be the cause of this rapid QPO.

[abstract 7 / 47] Yes (score: 6)
arXiv:2608.23107 [pdf, ps, other]

Title: Reconstructing the Auger UHECR Dipole: A Hybrid Analysis of 4LAC AGNs and Nearby Starburst Galaxies

Authors: Swaraj Pratim Sarmah, Umananda Dev Goswami, Sovan Chakraborty,

Comments:

Subjects: astro-ph.HE hep-th

Created: 2026-08-24; Updated: 2026-08-25; Datestamp: 2026-08-25

The large-scale dipole anisotropy observed by the Pierre Auger Observatory above $8$~EeV provides important clues about the origin of ultra-high-energy COSMIC RAYs (UHECRs). In this work, we investigate whether gamma-ray ACTIVE GALACTIC NUCLEi (AGNs) from the FERMI-LAT Fourth AGN Catalog (4LAC) can explain the observed dipole and examine the contribution of nearby starburst galaxies (SBGs). Incorporating source fluxes, redshift distributions, GZK attenuation, and a mixed-composition framework, we demonstrate that single-source populations of AGNs and SBGs alone fail to reproduce the observed Auger dipole. To resolve this, we construct a hybrid AGN+SBG model. The best-fit solution for the $8$--$16$~EeV interval requires a $23$\% AGN contribution and $45$\% SBG contribution, which gives a dipole amplitude of $5.03$\% while maintaining the dipole direction of ($104.1^\circ$, $-25.1^\circ$) with angular separation of $7.10^\circ$. In the other energy intervals also, we find that the nearby SBGs increasingly dominate the anisotropic component while AGNs provide a subdominant contribution alongside a quasi-isotropic background.

[abstract 8 / 47] Yes (score: 5)
arXiv:2601.14137 [pdf, ps, other]

Title: Minutes-long soft X-ray prompt emission from a compact object merger

Authors: An Li, Chen-Wei Wang, Niccolò Passaleva, Jie An, Bin-Bin Zhang, Eleonora Troja, Yi-Han Iris Yin, Yuan Liu, Shao-Lin Xiong, Li-Ping Xin, Yi-Xuan Shao, Jun Yang, Hui Sun, Dong Xu, Yu-Han Yang, Roberto Ricci, He Gao, Sarah Antier, Rosa L. Becerra, Jia-Xin Cao, Alberto Javier Castro-Tirado, Xin-Lei Chen, Ye-Hao Cheng, Yong Chen, Hua-Qing Cheng, Valerio D'Elia, Massimiliano De Pasquale, Yong-Wei Dong, Eslam Elhosseiny, Rob A. J. Eyles-Ferris, Maria Gritsevich, Xu-Hui Han, Dieter Hartmann, You-Dong Hu, Jing-Wei Hu, Shu-Mei Jia, Nino Kochiashvili, Wei-Hua Lei, Andrew J. Levan, Cheng-Kui Li, Dong-Yue Li, Hua-Li Li, Xiao-Bo Li, Zhi-Xing Ling, He-Yang Liu, Hou-Jun Lv, Daniele B. Malesani, Brendan O'Connor, Hai-Wu Pan, Shashi Bhushan Pandey, Ignacio Perez-Garcia, Daniëlle L. A. Pieterse, Marion Pillas, Yu-Lei Qiu, Andrea Saccardi, Rubén Sánchez-Ramírez, Wen-Jun Tan, Manasanun Tanasan, Nial R. Tanvir, Susanna D. Vergani, Jing Wang, Xiao-Feng Wang, Qin-Yu Wu, Shu-Xu Yi, Tillayev Yusufjon, Chen Zhang, Wen-Da Zhang, Yi-Jia Zhang, Guo-Ying Zhao, Chao Zheng, Shi-Jie Zheng, Chang Zhou, Ping Zhou, Bertrand Cordier, Jian-Yan Wei, Weimin Yuan, Shuang-Nan Zhang, Bing Zhang,

Comments: 53 pages, 15 figures, 5 tables, accepted for publication in Science Bulletin

Subjects: astro-ph.HE

Created: 2026-08-22; Updated: 2026-08-25; Datestamp: 2026-08-25

Compact object mergers are multi-messenger sources and known progenitors of some GAMMA-RAY BURSTs, bright flashes of high-energy radiation powered by a central engine, either an accreting BLACK HOLE or a neutron star. Our understanding of these events has so far been shaped primarily by observations in the gamma-ray band, leaving their prompt phase poorly constrained at lower energies. A long-lasting ($\approx$100 s) engine-driven X-ray emission was discussed to explain rapidly fading X-ray afterglows following several ($\approx$30%) bursts of short ($\lesssim$2 s) duration. However, this prompt X-ray component was not directly observed and past candidates were not confirmed. Here we report the discovery of EP250704a containing a minutes-long ($\sim$560 s) flash of soft (0.5--4 keV) X-rays immediately following the short ($\sim$0.4 s) GRB 250704B. The variability and spectral shape of this emission are inconsistent with the canonical picture of a hard, accretion-powered spike followed by a standard external-shock afterglow. Instead, the long-soft bump points to a distinct phase of prompt emission in X-rays, which would not have been detected without the soft X-ray coverage of Einstein Probe. The detection of a prompt soft X-ray counterpart in an otherwise ordinary short GRB shows that long-lasting X-ray emission is likely a common feature of merger-driven bursts and a promising electroMAGNETic counterpart to gravitational wave sources.

[abstract 9 / 47] Yes (score: 5)
arXiv:2608.21687 [pdf, ps, other]

Title: Galactic Electron-Positron Annihilation Emission from X-Ray Binaries with Transient and Persistent Jets

Authors: Argen Gian Detoito, Henric Krawczynski,

Comments: 25 pages, 9 figures, submitted to The Astrophysical Journal

Subjects: astro-ph.HE

Created: 2026-08-21; Updated: 2026-08-25; Datestamp: 2026-08-25

The Galactic Center exhibits a persistent 0.511 MeV emission characteristic of electron-positron annihilation. Various astrophysical sources may be responsible for supplying the positrons, yet their contributions with respect to the total annihilation rate is uncertain. X-ray binaries have historically been a primary candidate, possibly contributing a significant fraction of the Galactic positrons. X-ray binaries can produce positrons through the Blandford-Znajek mechanism, two-photon pair production in the corona, and/or one-photon pair production for strongly-MAGNETized compact objects. These positrons may then be channeled into the Interstellar Medium through JETs or winds. In this work, we argue that X-ray binaries cannot contribute to the electron-positron annihilation flux alone. We present 0.511 MeV line fluxes and all-sky maps produced by X-ray binaries and stellar flares from the Galactic stellar population, along with the gamma-ray continuum from positrons produced by X-ray binaries. To do so, we solve the particle transfer equation using Green's functions. The total morphology is slightly asymmetric towards negative longitudes and positive latitudes. We find five 0.511 MeV flux hotspots in the generated all sky maps and scrutinize the contribution of individual sources to these hotspots. Observations of these hotspots can reveal the contribution of X-ray binaries to the Galactic positrons. The upcoming Compton Spectrometer and Imager (COSI) mission could image a hotspot near Cygnus X-1. The detection of the other hotspots requires a telescope with improved arcminute angular resolution.

[abstract 10 / 47] Yes (score: 4)
arXiv:2608.22177 [pdf, ps, other]

Title: Plasmon-polaritons in a rarefied nonRELATIVISTIC neutron gas

Authors: P. O. Kazinski, A. M. Trushchuk,

Comments: 29 pp., 7 figs

Subjects: physics.plasm-ph astro-ph.SR

Created: 2026-08-23; Updated: 2026-08-25; Datestamp: 2026-08-25

The electroMAGNETic properties of a dilute unpolarized nonRELATIVISTIC neutron gas are described in the case when neutron-by-neutron scattering is negligible. The Gaussian (Maxwell-Boltzmann) and FERMI-Dirac one-particle density matrices for the neutron gas are considered, the typical space scale of variations of these density matrices being assumed to be much larger than the the typical space scale of variations of the electroMAGNETic field. The Green functions for the static effective Maxwell equations are obtained. The parameters of a nonequilibrium neutron gas are found where this gas possesses a ferroMAGNETic instability. The analog of Friedel oscillations is described. The properties of plasmon-polaritons in the neutron gas are revealed. It turns out that the dispersion law of longitudinal and transverse plasmon-polaritons has an infinite number of branches at a given momentum. The region of parameters where the plasmon-polaritons can be regarded as quasiparticles is found. The plasmon-polaritons on a Gaussian wave packet of a single electron are described. Their dispersion law proves to have an infinite number of branches at a given momentum. It is shown that there exist stable longitudinal plasmon-polaritons even on a single electron.

[abstract 11 / 47] Yes (score: 4)
arXiv:2608.22374 [pdf, ps, other]

Title: Galactic MicroQUASAR and Supernova Remnants Imprinting on Diffuse Neutrino and Gamma-Ray Sky

Authors: Shiqi Yu, Bing Theodore Zhang,

Comments: 8 pages, 4 figures

Subjects: astro-ph.HE

Created: 2026-08-23; Updated: 2026-08-25; Datestamp: 2026-08-25

Recent detections of Galactic diffuse neutrinos by IceCube and $γ$-rays by LHAASO offer direct probes into the origin of Galactic COSMIC RAYs. Conventional diffuse templates typically assume a single cosmic-ray injection spectrum across a wide energy range, without accounting for independent contributions from distinct accelerator populations. Here, we present a numerical framework that models Galactic diffuse neutrino and $γ$-ray emission that incorporates contributions from both microQUASAR and SUPERNOVA remnant populations. By anchoring CR injection to local observations and utilizing high-resolution 3D target gas distributions, our model suggests multi-population contributions to the diffuse sky: escaped COSMIC RAYs from SUPERNOVA remnants dominate below $\sim10\text{ TeV}$, while those from microQUASARs become the primary driver at higher energies. Our predicted neutrino flux agrees well with the recent 12-year IceCube measurements, establishing a physically motivated baseline for the diffuse hadronic background while leaving room for unresolved point-like sources. This flexible framework provides testable predictions for current and future multi-messenger observatories, accommodating diverse accelerator populations and updated observational constraints.

[abstract 12 / 47] Yes (score: 4)
arXiv:2608.22728 [pdf, ps, other]

Title: Probing AU-Scale Magnetic-Field Reversals in the Interstellar Medium with Pulsar Scintillation

Authors: Jacob Yen, Daniel Baker, Dongzi Li, Ue-Li Pen,

Comments:

Subjects: astro-ph.HE

Created: 2026-08-24; Updated: 2026-08-25; Datestamp: 2026-08-25

AU-scale structures in the interstellar medium have become relevant across several areas of astrophysics, from ISM microphysics to pulsar timing arrays and cosmic-ray (CR) propagation. Current sheets formed at MAGNETic-field reversals have drawn particular attention because they can deflect the dominant GeV CR population through large angles. Pulsar scintillation, an outstanding probe of plasma density, resolves these structures---but not their MAGNETic configuration. Conventional Faraday rotation measures (RM) are only marginally sensitive at AU scales and are further compromised by ionospheric systematics. We propose a method that isolates birefringence-induced POLARIZATION---the signature of MAGNETic reversal---by applying phase retrieval to polarized data. Pulsar scintillation further resolves ray paths separated by $\sim 1\,\rm{AU}$, enabling differential RM measurements that suppress the ionospheric common mode while preserving the AU-scale MAGNETic signal. We demonstrate the method on an archival observation of PSR B0834+06. Phase retrieval resolves the 1-ms scattering feature into two branches in Doppler-delay space. Under the corrugated current-sheet interpretation, these branches correspond to ray paths sampling opposite sides of an AU-scale current sheet. We measure a branch-to-branch RM difference of $(-9.3\pm3.2)\times 10^{-3}\text{ rad m}^{-2}$ at 2.9$σ$ across a 10-MHz band. The signal is consistent with a field reversal of $|Δ\langle B_\parallel \rangle| \simeq4.4\pm2.1\,μ\rm G$, sufficient to sustain a long-lived sheet. With only six independent subbands, we present this as a proof of concept rather than a definitive detection. If it proves scalable, its full implementation could constrain cosmic-ray transport and inform models of propagation-induced noise in pulsar timing arrays.

[abstract 13 / 47] Yes (score: 4)
arXiv:2608.23362 [pdf, ps, other]

Title: Breakout/Interchange Reconnection as a driver of Jets, Fast CME, and Solar Energetic Particles

Authors: Pankaj Kumar, Judith T. Karpen, David Lario, Benjamin J. Lynch, Peter F. Wyper, Spiro K. Antiochos, P. K. Manoharan,

Comments: 32 pages, 17 figures, ApJ (in press)

Subjects: astro-ph.SR physics.space-ph

Created: 2026-08-24; Updated: 2026-08-25; Datestamp: 2026-08-25

Understanding how energetic particles are accelerated and released from the low corona into the interplanetary medium during solar eruptions is crucial for space weather research. Here, we present multiwavelength observations of a solar eruption that are consistent with breakout RECONNECTion playing an important role in driving a fast coronal mass ejection (CME) and the associated solar energetic particle (SEP) event. Extreme-ultraviolet and radio observations reveal evidence of breakout RECONNECTion within a fan-spine topology. The filament eruption begins after the pre-eruption opening, accompanied by quasiperiodic JETs and associated downflows near the null point, as well as recurrent faint Type III radio bursts during the ongoing slow breakout RECONNECTion. Furthermore, the observations also reveal the formation of pre-eruption coronal rain via slow interchange RECONNECTion near the null point. A large-scale circular ribbon, along with simultaneous four hard X-ray footpoint sources and intense Type III radio bursts, was observed during the explosive breakout RECONNECTion that enabled opening of field lines and allowed energetic particles to escape into interplanetary space. In situ measurements by PSP and Wind confirm the prompt injection of electron beams consistent with the timing of the explosive breakout RECONNECTion. A fast shock associated with the erupting flux rope during interchange RECONNECTion played a major role in producing the gradual SEP event. These observations highlight the key role of breakout RECONNECTion in producing a fast CME/shock with the SEP release and acceleration process. These results have broader implications for particle acceleration and release processes in multiscale null-point topologies, which produce a continuum of eruptions ranging from small-scale JETs to large-scale CMEs.

[abstract 14 / 47] Yes (score: 4)
arXiv:2608.23387 [pdf, ps, other]

Title: White Paper on a Novel FFA-Based CEBAF Upgrade to 22 GeV

Authors: S. A. Bogacz, R. M. Bodenstein, K. E. Deitrick, B. R. Gamage, R. Kazimi, D. Khan, E. Nissen, S. Ogur, Y. Roblin, P. Rossi, J. S. Berg, S. J. Brooks, D. Trbojevic, V. Morozov,

Comments: This material is based upon work supported by the U.S. DOE, Office of Science, Office of Nuclear Physics contract DE-AC05-06OR23177

Subjects: physics.acc-ph

Created: 2026-08-24; Updated: 2026-08-25; Datestamp: 2026-08-25

We present a conceptual design for a cost-effective upgrade of the Continuous Electron Beam Accelerator Facility (CEBAF) to 22 GeV using non-scaling fixed-field alternating-gradient (FFA) arcs built from Halbach-style permanent MAGNETs. Building on the eight-pass energy-recovery demonstration at the Cornell--BNL CBETA test accelerator, the design replaces the highest-energy recirculation arcs with a pair of FFA arcs that simultaneously transport six passes spanning a factor-of-two momentum range. We describe the machine layout; including the injector, recirculating linacs, spreaders and recombiners, FFA arcs, splitters, transition and extraction regions; together with beam-dynamics validation studies covering emittance growth, SYNCHROTRON-radiation-driven dePOLARIZATION, and orbit correction, and we summarize permanent-MAGNET design, prototyping, and radiation-resiliency results. This white paper documents the accelerator physics underpinning a staged path to 22 GeV that preserves CEBAF's multi-hall, high-luminosity, polarized-beam capabilities.

[abstract 15 / 47] (score: 3)
arXiv:2509.10352 [pdf, ps, other]

Title: Can a gamma-ray dim radio BLAZAR produce a 200-PeV neutrino? The case of PMN J0606$-$0724 and KM3-230213A

Authors: Polina Kivokurtseva, Sergey Troitsky,

Comments: 17 pages, 3 figures

Subjects: astro-ph.HE

Created: 2026-08-22; Updated: 2026-08-25; Datestamp: 2026-08-25

An extremely energetic muon has been recently detected by the Cubic Kilometre Neutrino Telescope (KM3NeT), indicating the observation of a neutrino with the estimated energy of $\left( 2.2^{+5.7}_{-1.0} \right)\times 10^{17}$~eV. Radio BLAZAR PMN~J0606$-$0724, not detected in gamma rays, is located within the reported error region of the neutrino arrival direction, and was flaring at the time of the event. Here we demonstrate that the neutrino could be produced in a photohadronic interaction in its radio core. The necessary proton power is of order of the source's photon luminosity, and protons can be accelerated to the required energies in the core, while high-energy gamma rays cannot leave the source because of intense production of electron-positron pairs. Expected contribution of the population of similar flaring sources matches non-observation of energetic events by other neutrino telescopes.

[abstract 16 / 47] (score: 3)
arXiv:2606.01957 [pdf, ps, other]

Title: Radio Continuum Emission from Evolving Star-Forming Galaxies -- I. Correlations Involving the Total Synchrotron Luminosity

Authors: Sukanta Ghosh, Luke Chamandy, Charles Jose, Anvar Shukurov, Luiz Felippe S. Rodrigues, Fatemeh Tabatabaei,

Comments: 31 pages, 21 figures, and 8 tables. Accepted for publication in ApJ

Subjects: astro-ph.GA

Created: 2026-08-23; Updated: 2026-08-25; Datestamp: 2026-08-25

Synchrotron radiation dominates the continuum emission of star-forming galaxies in the frequency range from a few $\rm MHz$ to about $30\,\rm{GHz}$. We model the total SYNCHROTRON emission of a large population of evolving star-forming galaxies using the semi-analytic galaxy formation model GALFORM combined with the dynamo simulation code MAGNETIZER. Assuming local energy equipartition between COSMIC RAYs and MAGNETic fields, we calculate the specific SYNCHROTRON luminosity $L_ν$ for each simulated galaxy at various frequencies and find strong positive correlations between $L_ν$ and both the STAR FORMATION rate ($\rm SFR$) and characteristic galaxy rotation speed $V_{\rm rot}$ for redshifts up to $z\simeq 3$. At low redshifts, the turbulent MAGNETic field is found to dominate in the SYNCHROTRON luminosity, but the contribution of the large-scale MAGNETic field increases with redshift and becomes important for $z\gtrsim 1$. The correlation between $L_ν$ and $\rm SFR$ arises from the tight correlation between the disc gas mass $M_{\rm gas}$ and $\rm SFR$, and the correlation between $L_ν$ and $V_{\rm rot}$ is additionally a consequence of the stellar mass Tully--Fisher relation for main-sequence galaxies. At low redshifts, the model predictions and observational data compiled for this work show remarkable agreement, but a discrepancy arises at higher redshifts, where modelled $\rm SFR$ values are systematically smaller than those previously inferred from observations. These theoretical models will aid the interpretation of next-generation radio surveys with the Square Kilometre Array and other telescopes.

[abstract 17 / 47] (score: 3)
arXiv:2606.12355 [pdf, ps, other]

Title: UV-to-optical insights into the BH$^*$ model in little red dots

Authors: Rosa M. Mérida, Marcin Sawicki, Chris J. Willott, Gaia Gaspar, Kartheik G. Iyer,

Comments: Accepted for publication in A&A

Subjects: astro-ph.GA

Created: 2026-08-22; Updated: 2026-08-25; Datestamp: 2026-08-25

Little Red Dots (LRDs) are a heterogeneous class of objects, with several proposed scenarios for their physical nature and evolution. While these theories have been tested on individual LRDs using limited spectral features, a systematic Bayesian analysis of the LRD population incorporating the different models across a broad wavelength range is still lacking. In this study, we conduct a consistent ultraviolet (UV)-to-optical continuum fitting analysis of 99 LRDs at 2ACTIVE GALACTIC NUCLEus (AGN) component-we assess the performance of the BLACK HOLE star (BH*) model in describing the LRD population. We adopt broad priors and therefore do not impose any specific physical scenario. Our results show that only ~4% of LRDs with statistically robust solutions (81 objects in total) are best-fit by a BH* in the optical and a host galaxy in the UV. ~9% of LRDs show BB-dominated optical continua but lack a stellar component or exhibit AGN UV leakage. Most LRDs are dominated by stellar and/or AGN emission in the optical, with minor BB contribution. When we adopt a prior that disfavors a strong AGN continuum to enforce BH*-like solutions, the percentage of BH* systems increases to ~35%, highlighting the strong degeneracy between a BH* solution and alternative scenarios. Even when BH*-like solutions are enforced, many LRDs still require a stellar-dominated optical continuum. This could indicate limitations in the BH* model, as further supported by independent evidence, such as the detection of high-ionization emission lines in some LRDs.

[abstract 18 / 47] (score: 3)
arXiv:2606.12522 [pdf, ps, other]

Title: Magnetic fields at the dawn of structure formation I. The CARLA J1510+5958 proto-cluster

Authors: A. Pagliotta, A. Bonafede, C. Stuardi, C. J. Riseley, D. Vallés-Pérez, P. Tozzi, L. Di Mascolo,

Comments: 21 pages, 14 figures, published in A&A, shortened abstract to meet arXiv characters requirement

Subjects: astro-ph.CO astro-ph.GA

Created: 2026-08-24; Updated: 2026-08-25; Datestamp: 2026-08-25

Magnetic fields are a fundamental ingredient of the Universe, influencing the formation and evolution of cosmic structures. While MAGNETic fields in local galaxy clusters have been studied, their origin, amplification, and strength at high redshift are poorly understood. Proto-clusters represent the early stages of galaxy cluster formation, ideal for investigating the early MAGNETisation of the intra-cluster medium (ICM). We present a study of CARLA J1510+5958 proto-cluster at z = 1.72, observed with the JVLA in the L-band (1-2 GHz). We aim to investigate the MAGNETic field strength and structure in the proto-ICM and the role of AGN in MAGNETising the environment during early cluster formation. We analyse Faraday rotation on the polarised emission from the central radio-loud AGN using the Rotation Measure (RM) synthesis and QU fitting technique. We further interpret the observations with 3D simulations of gas density and turbulent MAGNETic fields, varying AGN orientation and path length. The two AGN lobes show different polarisation properties. The Western lobe exhibits a uniform RM (average $-115 \pm 32\text{ rad m}^{-2}$, dispersion $36 \pm 11\text{ rad m}^{-2}$), indicating a locally ordered MAGNETic field likely compressed by the lobe, while the Eastern lobe is depolarised. Although the asymmetry indicates a turbulent, MAGNETised medium, simulations rule out a purely isotropic random field for the Western lobe RM distribution. The QU fitting further suggests an internal Faraday component, interpreted as MAGNETised RELATIVISTIC plasma from the lobe mixed with the surrounding gas, indicating possible MAGNETisation of the ambient medium by the AGN. From this asymmetry, we constrain the average physical MAGNETic field in the proto-ICM to a lower limit of 0.4 $μ$G. These results confirm a MAGNETised proto-ICM at z = 1.72, proving early field amplification during cluster assembly.

[abstract 19 / 47] (score: 3)
arXiv:2607.20614 [pdf, ps, other]

Title: Gravitational Lensing Predictions from Wave Simulations of Fuzzy Dark Matter

Authors: Jiajun Zhou, Zhengxiang Li, Amruth Alfred, Ran Gao, Jeremy Lim, Zong-Hong Zhu,

Comments: 18 pages, 9 figures; ApJL in press. Comments are welcome

Subjects: astro-ph.CO

Created: 2026-08-21; Updated: 2026-08-25; Datestamp: 2026-08-25

In the cold DARK MATTER paradigm, ultra-light particles are emerging as strong contenders to conventional massive particles. A unique prediction of DARK MATTER comprising such ultra-light particles, known as fuzzy DARK MATTER (FDM), is the presence of strong density modulations throughout galactic halos due to wave interference, which -- when approximated by a Gaussian random field (GRF) -- have been proposed to account for the inability to reproduce the observed positions (when measured at sufficient precisions) and flux ratios of multiply-lensed images of QUASARs. Here, we predict for the first time the properties of gravitationally lensed images generated from 3-D density fields obtained by wave simulations that directly evolve the Schrödinger--Poisson equations. Using a novel framework to project these evolved density fields along various axes of the 3-D halo, we obtain the distribution of perturbations to the positions of lensed images. As an exacting test, we find that particles of mass $10^{-22}$ eV can reproduce the positions of the quadruply-lensed radio JETs in system HS 0810+2554 to a level better than that of either the GRF approximation or, to a greater extent, an NFW best-fit solution, both of which rely on accurately capturing the global 3-D density field of DARK MATTER halos. Our work highlights the importance of wave simulations for making accurate FDM lensing predictions and the potential for high-resolution observations of lensed systems to serve as a direct probe of the nature of DARK MATTER.

[abstract 20 / 47] (score: 3)
arXiv:2608.21876 [pdf, ps, other]

Title: Indirect evidence of the $2175\,\mathring{\mathrm{A}}$ extinction bump within the dusty torus of SDSS J141945.50+524648.0

Authors: Ze Li, Gaoyang Chen, Qifan Cui, Zheng Cai, Jianzhen Chen, Zhijian Luo, Chenggang Shu, Fengwu Sun, Hubing Xiao, Shaohua Zhang,

Comments: 9 pages, 4 figures, 1 table. Submitted to A&A

Subjects: astro-ph.GA

Created: 2026-08-22; Updated: 2026-08-25; Datestamp: 2026-08-25

We present a multi-wavelength study of the QUASAR SDSS J141945.50$+$524648.0 ($z=1.1599$), a member of the newly identified population of QUASAR-associated $2175\,\mathring{\mathrm{A}}$ dust absorbers. Utilizing JWST/NIRCam observations from the SAPPHIRES survey and archival data, we analyze the prominent $2175\,\mathring{\mathrm{A}}$ extinction bump detected in this object. The bump parameters are highly consistent with the Milky Way extinction curve, implying similar dust properties. Spectral analysis reveals a $\mathrm{Mg\,II}$ absorption doublet near the systemic velocity. Joint fitting of the $\mathrm{Mg\,II}$ and $\mathrm{Fe\,II}$ absorption lines favors a partial-covering model, yielding $C_{f,\rm BEL}=0.11^{+0.12}_{-0.07}$. Together with the small velocity offset ($Δv\approx96~{\rm km\,s^{-1}}$), these results favor an intrinsic absorber rather than an intervening system. Infrared SED modeling and double-peaked $\mathrm{Pa\,α}$ emission indicate consistent orientations of the dusty torus ($θ\approx60^{+7}_{-8}$ deg) and accretion disk ($i=63.7^{+10.9}_{-7.8}$ deg), suggesting a rim-penetrating line of sight through the torus. This configuration naturally explains the infrared emission, continuum extinction, and associated $2175\,\mathring{\mathrm{A}}$ bump, although a contribution from the host-galaxy ISM cannot be excluded. If associated with the torus, the carbonaceous carriers of the $2175\,\mathring{\mathrm{A}}$ feature may survive the intense AGN radiation field through localized shielding in optically thick dusty clumps. These results highlight the role of viewing geometry and dust distribution in regulating dust survival in QUASAR environments.

[abstract 21 / 47] (score: 3)
arXiv:2608.21920 [pdf, ps, other]

Title: Pair Discharges and Radio Emission from Pulsar Magnetospheres

Authors: Joonas Nättilä, Tuomo Salmi,

Comments: 18 pages, 8 figures. Comments welcome!

Subjects: astro-ph.HE physics.plasm-ph

Created: 2026-08-22; Updated: 2026-08-25; Datestamp: 2026-08-25

Radio pulsars can power their coherent radio emission through intermittent plasma discharges in MAGNETospheric gaps. The nonlinear coupling between particle acceleration, quantum electrodynamic (QED) processes, and electric field screening remains difficult to model self-consistently. We present an analytical concurrency model and first-principles particle-in-cell (PIC) simulations of polar cap discharges. The model predicts limit-cycle behavior where the electric field and plasma density oscillate with a frequency set by the local plasma frequency, modified by the plasma inertia. One-dimensional simulations with exact QED rates and realistic plasma parameters validate these predictions. The discharges generate pair multiplicities up to $M_\pm \sim 10^4$ and excite electric field oscillations with spectra consistent with pulsar radio microstructure. These results provide a theoretical framework connecting microphysical gap dynamics to macroscopic observables.

[abstract 22 / 47] (score: 3)
arXiv:2608.21940 [pdf, ps, other]

Title: Discovery of an Extremely Luminous Sporadic Radio Pulsar

Authors: Fengqiu Adam Dong, Robert Main, Jackson D. Taylor, Shion Andrew, Alyssa Cassity, Shami Chatterjee, Alice P. Curtin, Emmanuel Fonseca, B. M. Gaensler, Jason Hessels, Victoria Kaspi, Afrokk Khan, Lars Künkel, Mattias Lazda, Calvin Leung, Kiyoshi W. Masui, Ryan Mckinven, Mason Ng, Ayush Pandhi, Aaron B. Pearlman, Ziggy Pleunis, Alexander W. Pollak, Sachin Pradeep E. T., Scott M. Ransom, Paul Scholz, Kaitlyn Shin, Kendrick Smith, Ingrid Stairs,

Comments: Submitted to ApJL

Subjects: astro-ph.HE

Created: 2026-08-22; Updated: 2026-08-25; Datestamp: 2026-08-25

We have discovered PSR J2108+5055, an extremely luminous but sporadic mode-changing rotating radio transient (RRAT), with a period of 0.495 s using the Canadian Hydrogen Intensity Mapping Experiment/Fast Radio Burst instrument (CHIME/FRB). We show that the brightest pulse from PSR J2108+5055 has a flux density of 3.1+/-1.0 kJy, corresponding to a spectral luminosity of (7.5+/-2.3)x10^23 erg s^-1 Hz^-1, assuming a dispersion-measure-derived distance of 1.6+/-0.3 kpc. We place an upper limit on the duty cycle of PSR J2108+5055 at 0.002% and measure a surface MAGNETic field of 5.8x10^11 G, a characteristic age of 1.2x10^7 yr, and a spindown luminosity of 2.2x10^32 erg s^-1. Using a simple model based on the Green Bank North Celestial Cap (GBNCC) survey, we place an upper limit on the number of PSR J2108+5055-like sources with similar peak flux densities in the GBNCC survey area of ~80 RRATs. We show that if PSR J2108+5055 were placed at the edge of the Local Group of galaxies, the Five-Hundred-Meter Aperture Spherical Telescope (FAST) would detect its brightest pulse. The second brightest pulse has a peak flux density of 1.5+/-0.7 kJy, and FAST would detect such a pulse out to ~1 Mpc, covering the inner Local Group, including Andromeda.

[abstract 23 / 47] (score: 3)
arXiv:2608.22027 [pdf, ps, other]

Title: Pair Discharges and Radio Emission from Millisecond-Pulsar and White-Dwarf Magnetospheres

Authors: Tuomo Salmi, Joonas Nättilä,

Comments: 12 pages, 5 figures. Comments welcome!

Subjects: astro-ph.HE physics.plasm-ph

Created: 2026-08-22; Updated: 2026-08-25; Datestamp: 2026-08-25

Coherent radio emission is observed from compact astrophysical objects with relatively weak MAGNETic fields, including millisecond pulsars and white dwarfs, the latter being proposed as possible sources of long-period radio transients. In such environments, the standard pair discharge mechanism---driven by curvature radiation and one-photon pair production---can fail because the low MAGNETic field strength suppresses photon conversion. We analyze a discharge mechanism that operates efficiently in weak-field MAGNETospheres, including two-vertex quantum electrodynamic processes: inverse Compton up-scattering of background photons followed by either two-photon or one-photon pair creation depending on the seed photon temperature. Using first-principles radiative particle-in-cell simulations incorporating exact QED cross sections, we demonstrate that these mechanisms robustly generate pair cascades in millisecond-pulsar MAGNETospheres and in hot white-dwarf environments. The resulting system exhibits limit-cycle behavior and generates electroMAGNETic field fluctuations capable of producing coherent radio emission, providing a natural explanation for radio activity in low-field compact objects.

[abstract 24 / 47] (score: 3)
arXiv:2608.22735 [pdf, ps, other]

Title: Tidal disruption of stellar binaries as a pathway to exotic transients

Authors: Mauricio González-Servín, Emilio Tejeda, Susana Lizano, Luis A. Manzaneda, Raúl Cano-Villegas,

Comments: 28 pages, 16 figues; submitted to MNRAS; comments welcome

Subjects: astro-ph.HE

Created: 2026-08-24; Updated: 2026-08-25; Datestamp: 2026-08-25

Tidal disruption event (TDE) progenitors are commonly modelled as single stars on parabolic orbits around a supermassive BLACK HOLE (SMBH), yet observations point to a richer diversity of dynamical pathways. We show that the tidal separation of stellar binaries by a $10^6\,M_\odot$ SMBH provides a natural mechanism for producing eccentric TDEs. Using restricted three-body dynamics and smoothed particle hydrodynamics (SPH) simulations, we model a binary composed of a solar-like star (SLS) and a white dwarf (WD) on a parabolic orbit. The binary orbital phase governs the outcome: one component is captured onto a tightly bound orbit while the other is ejected as a hypervelocity object, naturally producing TDEs with eccentricities $e \neq 1$. We classify the resulting events into Elliptical TDEs (eTDEs) and Hyperbolic TDEs (hTDEs), which occur with equal probability. For $\sim 88\%$ of binary orientations the disruption is clean, with no mass accreted by the WD. The remaining $\sim 12\%$ lies in two narrow windows of binary phase in which the WD captures material and becomes a WD with debris envelope (WDDE). About a third of that range, $\sim 4\%$ of all orientations, involves a direct WD--SLS collision near pericenter, giving fallback that peaks up to five times earlier and twenty times higher than in the single-star case; for the innermost $\sim 1.5\%$ the total WDDE mass exceeds $1.4\,M_\odot$, although the degenerate core itself does not, since the captured material forms a non-degenerate envelope. This suggests outcomes ranging from nova-like events to peculiar red giant-like objects. Depending on the binary phase, the mechanism may also produce repeating partial TDEs (rTDEs) and quasi-periodic eruptions (QPEs). Binary--SMBH encounters thus provide a robust channel for generating diverse TDEs with distinct observational signatures.

[abstract 25 / 47] (score: 3)
arXiv:2608.22771 [pdf, ps, other]

Title: Timing, Polarization, and Single-Pulse Properties of Long-Period FAST Pulsars

Authors: Habtamu Menberu Tedila, Shijun Dang, Di Li, Pei Wang, Jianping Yuan, Rai Yuen, Na Wang, Shakhboz Khasanov,

Comments: 26 pages and 15 figures, submitted to Astrophysical Journal (ApJ)

Subjects: astro-ph.HE

Created: 2026-08-24; Updated: 2026-08-25; Datestamp: 2026-08-25

We present phase-connected timing and POLARIZATION measurements for two long-period FAST-CRAFTS pulsars, PSRs J0000+6252 and J2131+3642, and extend single-pulse emission-state analysis to a five-source sample including PSRs J1903+1407, J1502+4653, and J2112+4058. FAST L-band timing baselines span 414 to 511 days; the two pulsars have spin periods of 1.11 to 1.55 s, period derivatives of $(3.99$ to $4.06)\times10^{-15}~{\rm s~s^{-1}}$, characteristic ages of 4.34 to 6.16 Myr, surface MAGNETic fields of $(2.15$ to $2.52)\times10^{12}$ G, and spin-down luminosities of $(4.21\times10^{31}$ to $1.16\times10^{32})~{\rm erg~s^{-1}}$. Their rotation measures are $70.2\pm26.7$ and $-44.6\pm7.6~{\rm rad~m^{-2}}$, with linear POLARIZATION fractions of 17.6\% to 27.2\%. PSR J2131+3642 shows a short monotonic PA segment permitting a formal rotating-vector-model fit, though limited longitude coverage leaves the geometric parameters poorly constrained; PSR J0000+6252 has too few PA points for such a fit. Gaussian mixture modeling (GMM) of single-pulse energy distributions identifies null, weak, and burst components in PSRs J0000+6252, J1903+1407, J1502+4653, and J2112+4058, while J2131+3642 shows only weak and burst states. We also identify bright single pulses (peak intensity $\geq10\times$ the integrated average profile): 42 in J0000+6252, four each in J1903+1407 and J2112+4058, and none in J2131+3642 or J1502+4653. These bright pulses occur within the main emission window with no evidence of periodic recurrence, consistent with sporadic enhancements of the normal radio-emission beam. For J2112+4058, we measure a scattering timescale $τ_{\rm sc}=5.84\pm0.18$ ms at $ν_{\rm ref}=1.25$ GHz. Together, these results highlight the diversity of MAGNETospheric variability among slowly rotating neutron stars.

[abstract 26 / 47] (score: 3)
arXiv:2608.22835 [pdf, ps, other]

Title: ASKAP discovery of a pair of large radio bubbles: on the origin of odd radio circles

Authors: Renzhi Su, Minfeng Gu, Hengxiao Guo, Neelesh Amrutha, Liang Cheng, Fangzheng Shi, Wenwen Zuo, Ruiyu Zhang, Guobin Mou, Fulai Guo, Wenke Ren, Xuecheng Zheng,

Comments: 17 pages, 8 figures

Subjects: astro-ph.GA

Created: 2026-08-24; Updated: 2026-08-25; Datestamp: 2026-08-25

We report the serendipitous discovery of a large, low-surface-brightness radio bubble in 944 MHz continuum data from the ASKAP Evolutionary Map of the Universe (EMU) survey. The structure, centred on the elliptical galaxy LEDA 217397 at a redshift of $z=0.040$, spans $\sim$8.4 arcmin, corresponding to a projected diameter of $\sim$399 kpc, and consists of two partly overlapping shells both with radii of $\sim$114 kpc. The integrated flux density of the bubble is $56.8\pm2.9$ mJy at 944 MHz, implying a rest-frame 1.4 GHz luminosity of $\sim$ $1.4\times10^{23}$ W Hz$^{-1}$. Combining the EMU measurement with MWA GLEAM-X data at 88--185 MHz, we derive a steep integrated spectral index of $α=-1.04\pm0.04$, and a two-frequency spectral-index map suggesting a possible exterior flattening. Spectral Energy Distribution (SED) fitting indicates a massive ($\log M_{\ast}/M\odot = 10.97\pm0.09$), quiescent (SFR=$0.025\pm0.083\,M\odot$ yr$^{-1}$) early-type host with no mid-infrared AGN signature and no overdense environment. We compare the bubble with odd radio circles (ORCs) and large radio shells, and discuss three scenarios for its origin: a starburst-driven wind, a merger-driven shock, and AGN JET-inflated bubbles. The starburst wind is disfavoured on energetic grounds ($\gtrsim$$10^{59}$ erg required versus $\sim$$10^{8}$ yr electron lifetimes), and neither a halo-scale merger shock nor a spherical nuclear blast wave can explain the unusually regular, double-shell geometry; a bipolar nuclear outburst -- a relic AGN JET episode, possibly triggered by a supermassive-black-hole merger -- provides the most natural explanation, with later shocks possibly re-energising the plasma. Deeper broad-band radio, polarimetric, spectroscopic and X-ray observations are needed to confirm its nature.

[abstract 27 / 47] (score: 3)
arXiv:2608.23466 [pdf, ps, other]

Title: Helical JETs driven by a ring of LASER irradiation

Authors: Kian Orr, Brandon K. Russell, Kirill Lezhnin, Yang Zhang, Geoffrey Pomraning, Petros Tzeferacos, Hantao Ji, Lan Gao,

Comments: 9 pages, 6 figures

Subjects: physics.plasm-ph

Created: 2026-08-24; Updated: 2026-08-25; Datestamp: 2026-08-25

Plasma JETs are formed in various astrophysical systems as plasma is rapidly ejected from a source, with a subset of these JETs being MAGNETized and having a helical structure. Here, we demonstrate that helical JETs may be formed using a ring of LASER pulses that arrive on planar foils sequentially with increasing energy. The formation of the JETs and their properties, including kinetic helicity, are studied through a set of three-dimensional MAGNETo-hydrodynamics simulations with conditions informed by the parameters of the OMEGA LASER facility. We find that JETs with a higher degree of helicity may be generated under realistic experimental conditions when compared to a uniform JET. Synthetic x-ray and Thomson scattering diagnostics computed from simulated data demonstrate that the helical JET provides a unique fingerprint in both its morphology and plasma parameters. This laboratory helical JET platform may allow for controlled experimental study of the dynamics of helical plasma structures and, through interaction with other JETs or targets, can allow for studies of shear-driven turbulence and mixing relevant to interactions between astrophysical JETs and ambient clouds or crosswind.

[abstract 28 / 47] (score: 2)
arXiv:0905.2663 [pdf, ps, other]

Title: On the Relativistic Origin of spin: A Case for the "Rest Angular Momentum"

Authors: H. Razmi, A. MohammadKazemi,

Comments: 6 pages

Subjects: physics.gen-ph

Created: 2026-08-24; Updated: 2026-08-25; Datestamp: 2026-08-25

The intrinsic angular momentum, or spin, is a cornerstone of modern physics with profound applications from nuclear MAGNETic resonance to spintronics. While its mathematical structure within quantum theory is well-defined, its fundamental origin is often less emphasized. This paper revisits the genesis of spin by examining its emergence in RELATIVISTIC wave equations, its role in the Thomas precession, and its formulation for massless photons in electrodynamics. It is argued that these foundational elements collectively demonstrate that spin is inherently a consequence of RELATIVISTIC spacetime symmetry, and its full manifestation requires the quantum framework. Consequently, the term "rest angular momentum" offers a more conceptually accurate description, highlighting its origin as an intrinsic property manifest even in an object's rest frame, as dictated by the Poincaré group. Spin, as an invariant property of any object, is the angular momentum an elementary particle possesses in its rest frame, where its orbital angular momentum is zero. This perspective aims to bridge the gap between advanced theoretical concepts and pedagogical clarity, emphasizing that relativity is not merely about high-speed phenomena but is fundamental to the structure of matter itself.

[abstract 29 / 47] (score: 2)
arXiv:2508.20198 [pdf, ps, other]

Title: Two-particle number and transverse momentum balance function with event topology in pp collisions at $\sqrt{s}=13$ TeV

Authors: Subash Chandra Behera, Arvind Khuntia,

Comments: 15 pages, 11 figures

Subjects: hep-ex hep-ph

Created: 2026-08-24; Updated: 2026-08-25; Datestamp: 2026-08-25

The first study of charge-dependent two-particle differential number ($B$) and momentum balance functions ($P_{2}^{CD}$) with respect to an event shape variable, transverse spherocity, is reported. Results are presented from PYTHIA8 and EPOS-LHC model calculations in proton-proton (pp) collisions at $\sqrt{s} = 13$ TeV. To distinguish between back-to-back JET-like topologies and isotropic events, low and high transverse spherocity values are chosen. The correlation functions are measured as a function of averaged charged-particle multiplicity ($\langle N_{ch}\rangle$) in relative pseudorapidity ($Δη$) and relative azimuthal angle ($Δϕ$) with $|η| < 2.4$ and $0.2 < p_{\rm {T}} < 2.0$ GeV. A narrowing of the balance function width is observed in $Δη$ and $Δϕ$ from low- to high-multiplicity collisions. Wider balance functions are found in isotropic events as compared to JET-like events. However, for the momentum correlations, a nearly flat dependence is observed with $\langle N_{ch}\rangle$. This study investigates charge conservation mechanisms and their correlations for events classified with JET-like and isotropic topologies. To isolate medium-driven effects, we compare EPOS-LHC with its hydrodynamic core enabled and disabled and observed narrowing patterns in $B$ and $P_{2}^{CD}$ as a quantitative handle on radial-flow-induced localization of charge-balancing pairs.

[abstract 30 / 47] (score: 2)
arXiv:2601.05977 [pdf, ps, other]

Title: Comment on Nuclear Fusion 66, 016012 (2026) and arXiv:2508.03561 by Richard Fitzpatrick, A Simple Model of Current Ramp-Up and Ramp-Down in Tokamaks

Authors: Allen H Boozer,

Comments: The article being commented on is arXiv:2508.03561 as well as Nuclear Fusion 66, 016012 (2026)

Subjects: physics.plasm-ph

Created: 2026-08-24; Updated: 2026-08-25; Datestamp: 2026-08-25

The paper Nuclear Fusion \textbf{66}, 016012 (2026) by Richard Fitzpatrick is based on fundamental errors in the physics of the evolution of the poloidal MAGNETic flux in tokamaks. With the certainty of Faraday's Law, the slippage of the poloidal relative to the toroidal flux is given by the loop voltage. Some of the errors may be endemic to the tokamak community, such as the focusing on a quantity $ψ$ that has a subtle relation to the poloidal flux while essentially ignoring the toroidal flux. Other errors are due to an entanglement of in principle separable concepts and unjustified assumptions. Although Nuclear Fusion allowed the use ``private communication" as a reference to bolster misquotes, the response must be in arXiv because Nuclear Fusion will not allow any mention of ``private communication" in a response. This comment also derives a new and simple expression for the loop voltage, which has the validity of the parallel component of Ohm's law.

[abstract 31 / 47] (score: 2)
arXiv:2603.11028 [pdf, ps, other]

Title: XMM-Newton Observation and Optical Monitoring of the Candidate Redback Millisecond Pulsar 1FGL J0523.5$-$2529

Authors: J. P. Halpern, S. Bogdanov,

Comments: 11 pages, 5 figures, accepted by ApJ

Subjects: astro-ph.HE

Created: 2026-08-22; Updated: 2026-08-25; Datestamp: 2026-08-25

1FGL J0523.5$-$2529 is a FERMI selected redback millisecond pulsar candidate that exhibited luminous optical and X-ray flares in 2020-2021. We obtained a simultaneous X-ray and $U$-band observation with XMM-Newton in 2025, the first to cover the 16.5 hr orbit of 1FGL J0523.5$-$2529. The X-ray luminosity was in an intermediate state with a power-law photon spectral index of $Γ=1.53\pm0.02$. Apparent fluctuations were superposed on a broad, single-peaked modulation, the latter characteristic of intrabinary shock models in which the shock front is wrapped around the pulsar. The $U$-band light curve was dominated by ellipsoidal modulation of the nearly Roche lobe filling companion star, similar to that seen in ground-based optical photometry. We also used this effect in 10 years of ATLAS monitoring to improve the precision of the orbital period to 0.6881366(19) days. Considering that searches for radio pulsations from 1FGL J0523.5$-$2529 at all orbital phases have been unsuccessful, it may be that the shocked wind usually surrounds the pulsar.

[abstract 32 / 47] (score: 2)
arXiv:2606.26268 [pdf, ps, other]

Title: A nonRELATIVISTIC radiative transfer module for Idefix

Authors: Nicolas Scepi, Geoffroy Lesur,

Comments: Accepted for publication in A&A. 12 pages and 12 Figures. Corrected a typo in Eq. 20 compared to the published version thanks to the careful reading of David Melon Fuksman

Subjects: astro-ph.IM astro-ph.EP astro-ph.GA astro-ph.HE astro-ph.SR

Created: 2026-08-24; Updated: 2026-08-25; Datestamp: 2026-08-25

Radiation MAGNETohydrodynamic (RMHD) simulations are essential for comparisons with observations, particularly in the regime where fluids and radiation are dynamically coupled. Although computationally expensive, RMHD is becoming increasingly accessible with the advent of exascale computing. However, only a few public RMHD codes are currently able to fully exploit the diversity of modern accelerated architectures. We present a nonRELATIVISTIC radiative transfer module for the public MAGNETohydrodynamic code IDEFIX; it is built on the Kokkos library to ensure performance portability. Our goal is to provide a user-friendly RMHD code capable of running efficiently on current and future exascale supercomputers. The radiative transfer module is based on the M1 approximation and implemented using a split explicit-implicit scheme. A reduced speed of light approximation is employed to alleviate the timestep constraint imposed by radiation. The module supports several radiation Riemann solvers and Cartesian, cylindrical, and spherical geometries in one, two, and three dimensions. The implicit step relies on a simple matrix inversion, ensuring both robustness and high performance. Users can choose between built-in opacity models or supply tabulated opacities and custom user-defined functions. The radiative module of IDEFIX demonstrates excellent performance on accelerated architectures, including the AMD MI250X and MI300 partitions of the AdAstra supercomputer. On MI250X nodes, it achieves up to $7.\times 10^8$ cell updates per second per node, at a computational cost only 1.6 times higher than a pure MAGNETohydrodynamic simulation. These results establish IDEFIX as a fast, robust, and portable RMHD code suitable for the wider community.

[abstract 33 / 47] (score: 2)
arXiv:2607.15359 [pdf, ps, other]

Title: Observations of X-ray quasi-periodic eruptions

Authors: Thomas Wevers, Joheen Chakraborty, Erwan Quintin, Michal Zajaček, Margherita Giustini,

Comments: Invited review chapter for the book "Mysterious Repeating Signals from Centers of Galaxies" (Eds. Dheeraj Pasham, Eric Coughlin, Riccardo Arcodia, Petra Sukova, Itai Linial, Springer Singapore, expected in 2027). 39 pages, 11 figures

Subjects: astro-ph.HE astro-ph.GA

Created: 2026-08-24; Updated: 2026-08-25; Datestamp: 2026-08-25

Quasi-periodic eruptions (QPEs) are a novel class of repeating nuclear transients, discovered exclusively in the X-ray band to date. Since their initial discovery in 2019, the QPE sample has grown to 13 sources, exhibiting large amplitude, quasi-regular eruptive variability patterns that are distinct from previously known modes of massive BLACK HOLE variability. In this chapter, we provide a comprehensive overview of their observational characteristics. We review the X-ray spectral and timing properties of QPE eruptions, their long-term evolution, as well as the underlying quiescent emission, which is well described by thermally dominated, compact accretion disks. We discuss population-level emerging trends and selection biases, and present an updated census of their host galaxy properties. We also highlight the growing body of evidence pointing to strong connections between QPEs and tidal disruption events. Finally, we briefly summarize the key observational constraints on proposed QPE model interpretations, before looking ahead to the observational challenges and opportunities that will shape future progress in understanding this emerging population of nuclear transients.

[abstract 34 / 47] (score: 2)
arXiv:2608.21522 [pdf, ps, other]

Title: Beyond orientation: Evidence for distinct physical regimes among Little Red Dots and Little Blue Dots

Authors: L. Barrufet, J. S. Dunlop, M. L. Hamadouche, M. Mezcua, D. Herrero-Carrion, M. Santos-Lleo, R. Gottumukkala, D. Spinoso, C. T. Donnan,

Comments: 14 pages, 8 figures

Subjects: astro-ph.GA

Created: 2026-08-21; Updated: 2026-08-25; Datestamp: 2026-08-25

Little Red Dots (LRDs) and Little Blue Dots (LBDs) may represent the same population of compact ACTIVE GALACTIC NUCLEi (AGN) observed along different lines of sight. We test this scenario using a spectroscopic sample from the DAWN {\it JWST} Archive, selected based on common criteria for H$α$ equivalent width, UV continuum slope, and compactness. We use the optical continuum slope to distinguish between samples of 89 LRDs and 191 LBDs spanning $1 \lesssim z \lesssim 7.5$, and compare their continuum properties, H$α$ emission, and Balmer decrements. Consistent with previous studies, we find that LRDs exhibit broader H$α$ profiles than LBDs systematically (with median FWHM values of $2319^{+71}_{-64}$ and $1424^{+56}_{-43}~\mathrm{km\,s^{-1}}$, respectively). We also confirm that LRDs show larger Balmer decrements, with median $\log_{10}(F_{\rm Hα}/F_{\rm Hβ})=1.01\pm0.03$, compared with $0.47\pm0.01$ for LBDs. Line-of-sight effects could explain both results. However, most significantly, we find that the LRD fraction increases strongly with H$α$ line luminosity: LRDs are approximately six times more luminous in H$α$ than LBDs. This robust finding is much harder to explain through unification with LBDs by orientation. Despite their higher line luminosities, LRDs have a moderately lower median H$α$ equivalent width than LBDs, consistent with more of the raw emission being reprocessed into the rest-frame optical continuum in LRDs. These results, coupled with the systematically lower [O III]/H$β$ ratios found in LRDs and the decline of H$α$ equivalent width towards the reddest optical slopes, disfavour a simple orientation-based link between LRDs and LBDs, and are instead more consistent with the predictions of gas-cocoon models in which increasing gas column density explains the apparent transition from LBDs to LRDs.

[abstract 35 / 47] (score: 2)
arXiv:2608.21609 [pdf, ps, other]

Title: When the stars don't align: Investigating inconsistencies in binary BLACK HOLE formation across population synthesis codes

Authors: Alexandra G. Guerrero, Michael Zevin, Duncan B. Maclean, Katelyn Breivik, Carl L. Rodriguez, Max M. Briel, Daniel E. Holz,

Comments: 40 pages, 22 figures, 1 table

Subjects: astro-ph.HE astro-ph.GA astro-ph.SR

Created: 2026-08-21; Updated: 2026-08-25; Datestamp: 2026-08-25

Binary population synthesis (BPS) codes are extremely useful tools for investigating both the end-to-end lives of binary stars as well as a myriad of astrophysical phenomena observed in the Universe. Given the widespread use of BPS in modern astrophysical research, it is imperative to systematically compare BPS codes across the spectrum of computational efficiency, flexibility, and physical realism to gauge their consistency and robustness. In this work, we perform BPS using three modern codes---the rapid code $\texttt{COSMIC}$, the hybrid code $\texttt{METISSE}$ integrated into $\texttt{COSMIC}$, and the detailed code $\texttt{POSYDON}$---on three single-metallicity populations of identical initial binaries, ensuring consistent choices in physical parameterizations where possible. Investigating the final population of merging binary BLACK HOLEs (BBHs) as a test case, we find stark differences in the properties, formation pathways, and progenitors across the three codes. In an initial population of one million binary stars at $0.01 Z_\odot$, each code results in $\sim 5,000-9,000$ BBHs that merge within a Hubble time. However, only one initial binary becomes a BBH merger in all three codes, and $\lesssim 14 \%$ of BBH progenitors consistently merge in two codes. Binaries that become BBH mergers in two codes often go through different evolutionary pathways and result in different final properties. In short, the codes are inconsistent in predicting BBH merger properties, even for identical initial binary systems. Our results highlight the need for systematic comparisons of BPS techniques, for a deeper understanding of physical and computational differences between BPS codes, and for caution in over-interpreting the results from any BPS code. (Abridged)

[abstract 36 / 47] (score: 2)
arXiv:2608.21611 [pdf, ps, other]

Title: AXUV synthetic diagnostic for ASDEX Upgrade and its application for SPI simulations

Authors: Ferenc Lengyel, Weikang Tang, Matthias Hölzl, Matthias Bernert, Matěj Tomeš, Peter Halldestam, Paul Heinrich, Gergely Papp, Stefan Jachmich, Umar Sheikh, Mathias Dibon, Pascal de Marné, Jörg Hobirk, Thomas Eberl, Gergő I. Pokol, for the ASDEX Upgrade Team, the EUROfusion Tokamak Exploitation Team,

Comments: 16 figures (some multi-panel), 2 supplementary movies. Submitted to Plasma Physics and Controlled Fusion

Subjects: physics.plasm-ph

Created: 2026-08-21; Updated: 2026-08-25; Datestamp: 2026-08-25

We introduce an Absolute eXtended UltraViolet (AXUV) diode-based camera forward-modelling tool to support the validation of mitigated disruption simulations and the interpretation of experimental phenomena, with applications to the ASDEX Upgrade (AUG) tokamak. AXUV diodes measure electroMAGNETic radiation across a wide spectral range with a significantly higher time resolution (~microseconds) than foil bolometers (~milliseconds), albeit with a non-uniform spectral responsivity. AXUV is suitable for examining fast phenomena, such as shattered pellet injection (SPI), where the radiation localisation and radiated power provide information on the deposition of pellet material. Due to the characteristics and degradation of AXUV diodes, absolute power measurements are subject to large systematic uncertainties, especially when the spectra are time-varying, as in e.g. mixed Ne/D2 SPI experiments. These challenges motivated the development of a synthetic diagnostic within the Cherab-Raysect optical modelling framework, which is applied here to four AXUV cameras in two poloidal cross-sections of AUG. The synthetic diagnostic provides a means to understand how the diodes measure radiation under SPI conditions and to connect first-principles plasma simulations with experimental measurements. The details of the synthetic diagnostic are presented, and the capabilities are illustrated with applications to AUG SPI simulations performed in JOREK. The synthetic signals generated from these simulations are compared with experimental measurements from the 2022 SPI campaign and show qualitatively similar features in many respects. Particularly good agreement was found in the time evolution of the studied high Ne-content (10%) pellet, whereas a different, low Ne-content (0.17%) case exhibited more pronounced differences, likely due to the absence of background impurities in the underlying SPI simulations.

[abstract 37 / 47] (score: 2)
arXiv:2608.21672 [pdf, ps, other]

Title: Kerr-Newman and genuine Kerr BLACK HOLEs in the Bertotti-Robinson MAGNETic field

Authors: Hryhorii Ovcharenko, Jiri Podolsky,

Comments: 8 pages, 1 figure

Subjects: gr-qc astro-ph.HE hep-th

Created: 2026-08-21; Updated: 2026-08-25; Datestamp: 2026-08-25

We present a spacetime that describes a rotating and charged BLACK HOLE immersed in an external MAGNETic field. This exact solution to the Einstein-Maxwell equations has a surprisingly simple form which reduces to standard Kerr-Newman metric, and to the uniform Bertotti-Robinson MAGNETic universe. We show that the Kerr-BR solution presented in [Phys. Rev. Lett. {\bf 135}, 181401 (2025)] has a special charge, and we identify a genuine Kerr BLACK HOLE without any charge, in the MAGNETic field. In the weak-field limit it gives the Wald solution. We analyze main physical properties of the new family, namely singularities, horizons, regularity of axes, charges, entropy and temperature.

[abstract 38 / 47] (score: 2)
arXiv:2608.21737 [pdf, ps, other]

Title: State-Space Model-Enabled Reinforcement Learning for Magnetic Configuration Controlon EXL-50U

Authors: Pei Guo, Zhengyuan Chen, Jianguo Chen, Xuanhe Wang, Guoyang Shi, Siqi Ding, Yapeng Zhang, Lei Xing, Yong Liu, Xiang Gu, Tiantian Sun, Xiuchun Lun, Jia Li, Zhengxiong Wang, Huasheng Xie, Hanyue Zhao, Yuejiang Shi, Xianming Song, Tianyuan Liu, EXL-50U Team,

Comments:

Subjects: physics.plasm-ph

Created: 2026-08-22; Updated: 2026-08-25; Datestamp: 2026-08-25

Accurate feedback control of the plasma current ($I_p$) and centroid position $(R_c,Z_c)$ is essential for the stable operation of spherical torus (ST) plasmas. Conventional proportional-integral-derivative (PID) controllers require extensive manual tuning and struggle with the fast, strongly coupled dynamics that arise as plasma performance improves. Reinforcement learning (RL) has recently emerged as a promising alternative to such complex MAGNETic control problems, yet its practical deployment on ST devices remains challenging. This paper presents a practical RL controller for the EXL-50U ST, trained within a rigid RZIP state-space model (SSM) that enables efficient offline policy learning. A lightweight plasma position reconstructor is developed to estimate $(R_c,Z_c)$ from MAGNETic probe signals within the real-time control cycle. The trained policy is seamlessly deployed on the EXL-50U plasma control system, achieving stable regulation of $I_p$ and $(R_c,Z_c)$ and sustaining discharges up to 650 ms under RL control. These results demonstrate the feasibility and practical potential of model-informed RL for MAGNETic configuration control in ST devices, offering a promising direction beyond conventional PID-based schemes.

[abstract 39 / 47] (score: 2)
arXiv:2608.22020 [pdf, ps, other]

Title: Finite-Solid-Angle Boltzmann Radiation Transport on Dynamical Spacetimes in AthenaK

Authors: Hengrui Zhu, Alexander J. Dittmann, Lizhong Zhang, James M. Stone, Eduardo Mario Gutierrez, David Radice,

Comments:

Subjects: astro-ph.HE gr-qc

Created: 2026-08-22; Updated: 2026-08-25; Datestamp: 2026-08-25

We extend the finite-solid-angle general RELATIVISTIC radiation transport method of C. J. White et al. (2023) to time-dependent spacetimes represented in ADM form. This Valencia-type solver retains the angular transport and local implicit matter coupling of the original HARM-type solver, but replaces its time-independent Kerr--Schild tetrad and conserved-variable normalization with an Eulerian formulation. A Cholesky-gauge spatial tetrad makes the frame and its derivatives algebraic functions of the ADM variables, providing smooth, metric-compatible angular transport. The resulting transport system couples directly to an evolving spacetime, agnostic to the gauge evolution equations. Our test suite, including flat and curved beams, radiation--fluid coupling, and time-dependent geometries, establishes the accuracy and robustness of this approach. We further apply the Valencia-type solver to a radiative circumbinary disk, illustrating its potential for multi-messenger studies of dynamical strongly gravitating systems.

[abstract 40 / 47] (score: 2)
arXiv:2608.22211 [pdf, ps, other]

Title: Wavefront-Guided Electron Injection for Direct Laser Acceleration in Relativistic Laser-Driven Plasma Channel

Authors: Heng Wang, Liang Sheng, Long Zeng, Yang Li, Zheng Gong,

Comments:

Subjects: physics.plasm-ph physics.acc-ph

Created: 2026-08-23; Updated: 2026-08-25; Datestamp: 2026-08-25

We investigate electron injection into direct LASER acceleration (DLA) in RELATIVISTIC LASER-driven plasma channels using particle-in-cell simulations. We identify and characterize a wavefront-guided injection mechanism, in which electrons are continuously fed into the plasma channel through the density pile-up layer at the LASER-pulse front. Phase-space analysis reveals a localized injectable region within the pile-up layer, indicating that only a selected subset of electrons satisfies the conditions required for the subsequent direct LASER acceleration. This mechanism provides a physical interpretation for the high-charge capability of DLA by explaining how electrons are continuously supplied to the accelerating channel. Beyond this continuous supply process, the injection dynamics are further modulated by the periodic variation of the carrier phase at the LASER-pulse front. The spatial locations of injected electrons are found to be closely associated with MAGNETic-island structures formed under LASER-phase modulation, suggesting that the LASER wavefront not only supplies electrons but also organizes their entry into the accelerating channel. These findings advance the physical understanding of energetic-electron generation in RELATIVISTIC LASER-driven subcritical-density plasma channels and are relevant to the development of compact DLA-based particle and radiation sources.

[abstract 41 / 47] (score: 2)
arXiv:2608.22240 [pdf, ps, other]

Title: Primordial Asymmetries, Primordial Equation of State & Primordial Black Holes

Authors: Maël Gonin, Julien Froustey, Albert Escrivà, Alberto Magaraggia, Günther Hasinger, Florian Kühnel,

Comments: 27 pages totals, 16 main text pages, 6 main text figures, 3 appendix, 9 appendix figures

Subjects: astro-ph.CO

Created: 2026-08-23; Updated: 2026-08-25; Datestamp: 2026-08-25

We study the thermal history of the primordial Universe in presence of non-zero lepton and baryon asymmetries. Considering different scenarios, we determine the equation of state (EoS) of the Universe from T = 10 GeV down to T = 1 keV, spanning the QCD transition, hadron gas phase and neutrino decoupling epochs. Using a combination of numerical codes, we track the cosmic trajectories of chemical potentials associated with the baryonic, leptonic and electric charges, and follow the evolution of lepton asymmetries including through the era where neutrino oscillations take place. Combining peak theory with numerical-relativity simulations of the collapse threshold, we show the EoS-induced modifications to the primordial BLACK HOLE (PBH) mass spectrum. We determine the associated Gravitational Wave (GW) signal, showing how lepton asymmetries and a particular spectral index of curvature perturbations can be hinted at by current ground interferometer-based GW observations. Finally, we discuss constraints and positive evidence for PBHs.

[abstract 42 / 47] (score: 2)
arXiv:2608.22249 [pdf, ps, other]

Title: Extreme mass-ratio inspirals around rotating accelerating BLACK HOLEs

Authors: Xin-Dong Du, Tao Zhou, Wei Xiong, Tieguang Zi, Peng-Cheng Li,

Comments: 19 pages, 5 figures, 1 table

Subjects: gr-qc astro-ph.HE

Created: 2026-08-23; Updated: 2026-08-25; Datestamp: 2026-08-25

Extreme mass-ratio inspirals (EMRIs) can magnify small departures from Kerr dynamics into appreciable gravitational-wave phase shifts accumulated over many orbital cycles. We exploit this sensitivity to investigate the imprint of a rotating BLACK HOLE's acceleration on an EMRI waveform. The spinning C metric poses two obstacles to the standard Kerr flux framework: the spacetime is not asymptotically flat, and the acceleration breaks the reflection symmetry that supports exactly equatorial circular timelike orbits. For sufficiently small acceleration $AM$, we therefore formulate the calculation in an intermediate Kerr-like wave zone satisfying $M/r\ll1$ and $Ar\ll1$, and construct a near-equatorial circular orbit by examining its coupled radial--polar stability. We derive the separated point-particle source for the spin$-2$ radial Teukolsky equation, construct a regular normalized angular solution, solve the radial equation using the Sasaki--Nakamura transformation and the Green function method, and couple the resulting horizon and far-zone fluxes to the adiabatic evolution of stable near-equatorial circular orbits. The framework recovers the Kerr limit and reproduces the dominant $l=2$ Kerr fluxes with relative errors of order $10^{-7}$. Acceleration modifies both radiation reaction and the orbital frequency, producing a characteristic nonmonotonic accumulated dephasing. For $M=10^6M_\odot$, $m_s/M=10^{-5}$, $a/M=0.7$, and $AM=3\times10^{-7}$, the dominant-mode dephasing slightly exceeds $1$ rad over one year. Thus even weak acceleration can generate an order-radian secular phase imprint on long-duration EMRIs within the controlled regime of the present approximation.

[abstract 43 / 47] (score: 2)
arXiv:2608.22486 [pdf, ps, other]

Title: Stationary electron vortex states in a plasma bubble field

Authors: Hui-Dong Huang, Qi Meng, Zhi-Bin Wang, Liang Lu, Jian Chen, Li-Ping Zou,

Comments:

Subjects: physics.acc-ph physics.plasm-ph

Created: 2026-08-23; Updated: 2026-08-25; Datestamp: 2026-08-25

Plasma wakefield accelerators (PWFAs) offer accelerating gradients of 10-100~GV/m and RELATIVISTICally propagating plasma bubbles capable of confining charged particles. We study the stationary states of a vortex electron at the bubble center by solving the corresponding quasi-RELATIVISTIC Schrödinger equation. Analytical solutions are obtained with Laguerre-Gaussian transverse modes and Hermite-Gaussian longitudinal envelopes. Comparing the resulting beam parameters with experimentally accessible vortex-electron bundles, we find that the transverse beam waist supported by the plasma bubble is comparable to that achieved by current electron-optical techniques. The longitudinal confinement further provides a favorable parameter regime for stable injection. Our results indicate the feasibility of maintaining localized vortex-electron states in a plasma-bubble wakefield and provide an analytical starting point for investigating their subsequent acceleration and stability.

[abstract 44 / 47] (score: 2)
arXiv:2608.22940 [pdf, ps, other]

Title: Extensive Air Showers Parameters Estimation Using Machine Learning Techniques with Simulations of the FAST Telescope

Authors: Jiř\'ı Kvita, Monika Machalová, Radek Př\'ıvara, Rostislav Vodák, Jan Tomeček,

Comments:

Subjects: astro-ph.HE

Created: 2026-08-24; Updated: 2026-08-25; Datestamp: 2026-08-25

We present the capabilities of the Fluorescence detector Array of Single-pixel Telescopes (FAST) observatory in the single telescope configuration as an important step towards the possible future large-field observatory for detecting ultra-high-energy COSMIC RAYs. Reconstruction of main shower physics parameters are explored on noise-free simulated events using machine learning techniques in the challenging domain of a low-intensity transient signal. We find a very good correlation between the true and reconstructed energy of the shower even with the information from just the four photomultipliers of the single FAST telescope, and a reduced performance for the maximum of the shower development Xmax, using various architectures of artificial deep and convolutional neural networks, with a comparison to a benchmark gradient boost regression model. The resolution in the energy is found at the sub-percent level, while in Xmax it is~$5\%$. The relative difference between predicted and true values is under one percent for energy, while for Xmax it ranges from $-8\%$ to $+17\%$, which can be attributed to the limited information from the single FAST telescope configuration. The results constitute an important capabilities verification and a lesson learned with implications for established FAST prototypes as well as for more complex configurations of the FAST observatory under construction.

[abstract 45 / 47] (score: 2)
arXiv:2608.23174 [pdf, ps, other]

Title: Model dependent analytic spin torsion corrections to Blandford Znajek energy extraction in Einstein Cartan gravity

Authors: Jingxu Wu, Liangyu Luo, Zhenzhou Lei, Xiao Heng,

Comments:

Subjects: physics.gen-ph

Created: 2026-08-24; Updated: 2026-08-25; Datestamp: 2026-08-25

We investigate the leading near-horizon response of Blandford-Znajek energy extraction to a compact, neutral spin-polarized source within minimally coupled Einstein-Cartan-Dirac-Maxwell theory. Eliminating the algebraic contortion yields an effective axial contact interaction, which we embed into a conserved, anisotropic phenomenological completion. Working at leading order in the torsion parameter $ε_T$, spatial anisotropy $ξ$, and slow rotation $χ=a/M$ on the fixed-ADM branch, we derive the modified energy extraction rate at optimal load. We find that the leading-order power ratio $P_{\rm BZ}^{\rm EC}/P_{\rm BZ}^{\rm K}$ receives distinct contributions from rotational dragging ($\ell=1$) and MAGNETostatic flux redistribution ($\ell=2$). In the isotropic limit ($ξ=0$), the power is enhanced for a co-rotating completion and suppressed for a counter-rotating one, whereas for $ξ\neq0$ the net shift depends on the polar quadrupole response. We also formulate the generalized Znajek identity and linearized Grad--Shafranov framework, demonstrating that undetermined load-factor shifts leave the leading power coefficient invariant due to stationarity at the matched load point.

[abstract 46 / 47] (score: 2)
arXiv:2608.23188 [pdf, ps, other]

Title: An improved view of cosmic-ray transport and the galactic outflow in NGC 253

Authors: Shengtao Wang, George Heald, Stefan W. Duchesne, Xiaohui Sun, Guangxing Li, Jiangtao Li, Chao-Wei Tsai, Andrew J. Battisti, Mark Seibert, Kathryn Grasha, Jeff A. Rich, Rachael L. Beaton, Barry F. Madore, Jun Xu,

Comments: 20 pages, 20 figures and 3 tables. Accepted for publication in A&A

Subjects: astro-ph.GA

Created: 2026-08-24; Updated: 2026-08-25; Datestamp: 2026-08-25

The nearly edge-on starburst galaxy NGC 253 exhibits extended multiwavelength halo emission, making it an ideal laboratory for studying disk-halo transport. We present improved ASKAP 943 MHz and MWA 216 MHz total-intensity images with resolutions of 13 and 45 arcsec and rms noise levels of 16 $μ$Jy beam$^{-1}$ and 1 mJy beam$^{-1}$, respectively. After subtracting the thermal emission, we fitted the vertical SYNCHROTRON emission intensity and spectral-index profiles with one-dimensional advection and diffusion models. The ASKAP image reveals a loop-like structure in the northwestern radio spur extending to $\sim9$ kpc above the disk, while the southeastern spur reaches $\sim8$ kpc. The vertical profiles are best fitted by exponential components in the central region and Gaussian components in the outer regions, indicating advection-dominated CRE transport in the center and diffusion elsewhere. In the central region, the advection speed increases exponentially with height and reaches the estimated escape speed at about 5.5 kpc. The spatial correspondence with star-forming and X-ray-emitting regions indicates that CRE advection traces the bulk motion of the MAGNETized outflow. Below $\sim5.5$ kpc, the combined thermal, MAGNETic, cosmic-ray, and ram pressures exceed the estimated gravitational pressure, consistent with acceleration of the galactic wind. These results demonstrate the power of sensitive low-frequency radio observations for probing CRE transport and galactic outflows.

[abstract 47 / 47] (score: 2)
arXiv:2608.23522 [pdf, ps, other]

Title: Disentangling propagation effects from Fast Radio Burst spectra: An analysis on simulated data

Authors: Aishwarya Kumar, Fereshteh Rajabi, Martin Houde,

Comments: 16 pages, 7 figures, to be submitted to New Astronomy

Subjects: astro-ph.HE

Created: 2026-08-24; Updated: 2026-08-25; Datestamp: 2026-08-25

We present a methodology to decouple propagation effects, specifically scattering and dispersion, from the intrinsic spectro-temporal properties of repeating Fast Radio Bursts. Utilizing the Triggered Relativistic Dynamical Model, and assuming superradiance as the emission mechanism, we generate simulated sub-bursts and inject controlled levels of scattering and residual dispersion. For each burst, we measure the sub-burst slope, defined as the trajectory of the centroids in the dynamic spectrum, and the characteristic duration of the burst profile. We then fit a modified sub-burst slope law to the resulting slope-duration measurements to recover the scattering timescale, residual dispersion measure, and other model parameters. Under the thin-screen approximation, the scattering timescale at $1~\mathrm{GHz}$ is precisely recovered, typically to within $\sim 1-2\%$ of the true value. In contrast, the residual dispersion is recovered with comparatively lower precision, with median absolute errors of $\sim 0.3-0.6\ \mathrm{pc \, cm^{-3}}$, reflecting its weaker constraint and degeneracy with an intrinsic parameter. Despite this, the modified sub-burst slope law successfully reproduces the spectro-temporal evolution and accurately constrains the scattering properties even for diverse intrinsic burst populations. These results demonstrate that our framework yields a tractable method for separating propagation-induced distortions from intrinsic emission characteristics to a meaningful degree, enabling more reliable inference of the physical properties of FRB sources.