Current date: 2026-07-23

Setting default datestamp limit: 0

Datestamp limit: 2026-07-23 (0 days ago)

Created/updated limit: 2026-07-16 (7 days ago)

Suggested sets: physics, physics:astro-ph, physics:gr-qc, physics:physics

Setting default set: physics

OAI-PMH request: http://export.arxiv.org/oai2?verb=ListRecords&from=2026-07-23&until=2026-07-23&set=physics&metadataPrefix=arXiv

Scoring abstracts

Number of records retrieved: 675

Keyword score statistics

score 12 -- 1 abstracts

score 9 -- 2 abstracts

score 8 -- 1 abstracts

score 7 -- 1 abstracts

score 5 -- 3 abstracts

score 4 -- 5 abstracts

score 3 -- 11 abstracts

score 2 -- 12 abstracts

in total -- 36 abstracts

Articles that appeared on 2026-07-23

[abstract 1 / 36] Wow! (score: 12)
arXiv:2607.20375 [pdf, ps, other]

Title: Probing the High-Energy Emission of the VHE-emitting Changing-Look Blazar B2 1420+32

Authors: Anjum Peer, Zahir Shah, Sikandar Akbar, Bari Maqbool, Ranjeev Misra,

Comments:

Subjects: astro-ph.HE

Created: 2026-07-22; Updated: 2026-07-23; Datestamp: 2026-07-23

We present a multi-wavelength temporal and spectral study of the changing-look BLAZAR B2~1420+32 using \emph{FERMI}-LAT, \emph{SWIFT}-XRT, and \emph{SWIFT}-UVOT data from MJD~58818--60721. The source reached a peak 0.1--300~GeV photon flux of $(4.62 \pm 0.29) \times 10^{-6}\,\mathrm{ph\,cm^{-2}\,s^{-1}}$ around MJD~60488, about 60 times the 4FGL-DR4 average, during which the photon index hardened to $2.19 \pm 0.14$; the flux--index evolution shows only weak evidence for global harder-when-brighter behaviour. The fractional variability is strongly energy dependent, largest in $γ$-rays, substantial in the optical/UV, and low in X-rays. Strong $γ$-ray--optical/UV correlations and a moderate $γ$-ray--X-ray correlation indicate that the X-ray emission tracks the $γ$-ray variability less closely than the optical/UV emission. The X-ray spectra are best described by a log-parabola, and the negative curvature measured in four of the five states suggests that the X-ray band samples the transition between the high-energy tail of the SYNCHROTRON component and the onset of the inverse-Compton component. We identified five activity states and modelled the high-energy (X-ray and $γ$-ray) component of their broadband spectral energy distributions (SEDs) using SYNCHROTRON self-Compton (SSC), external Compton (EC), and SSC+EC scenarios. The SSC-only and EC-only models either require physically disfavoured parameters or fail to reproduce the VHE emission, whereas SSC+EC provides the most self-consistent description, with a seed-photon temperature of $\sim 10^{3}$~K favouring an infrared torus origin. The brighter states require larger bulk Lorentz factors and higher JET powers, while the MAGNETic field varies only modestly, indicating that the flux evolution is governed by a combination of Doppler boosting and JET energetics.

[abstract 2 / 36] Wow! (score: 9)
arXiv:2607.19869 [pdf, ps, other]

Title: Peculiar Behavior of Optical Polarization in Blazar 1ES 1959+650: Role of Jet Magnetic Field and Geometry

Authors: A. Singh, A. Tolamatti, K. K. Singh, A. C. Gupta, K. K. Yadav,

Comments: 10 pages, 9 figures, 3 table, Accepted for Publication in Physical Review D

Subjects: astro-ph.HE

Created: 2026-07-22; Updated: 2026-07-23; Datestamp: 2026-07-23

Measurements of high degree of optical POLARIZATION from BLAZARs provide a strong evidence for the optically thin SYNCHROTRON radiation from the RELATIVISTIC leptons in the JET. This in turn characterizes the presence of a partially ordered MAGNETic field in the emission region. However, the topology of MAGNETic field and acceleration of electrons to ultraRELATIVISTIC energies within the BLAZAR JET are poorly understood. In this work, we investigate the decade long optical light curve of the well-known BLAZAR 1ES 1959+650 to probe the role of JET MAGNETic field in the peculiar behavior of the highly varying degree of linear POLARIZATION in the wavelength band 500- 700 nm. The optical light curves in V and R-bands exhibit a strong flare without any significant change in the contemporaneous degree of linear POLARIZATION. However, the degree of linear POLARIZATION shows strong positive and negative/anti-correlations with the V and R-band fluxes measured during the epochs before and after the flare, respectively. This can be satisfactorily explained using the helical MAGNETic field and transverse shock under the framework of a RELATIVISTIC JET with modestly varying orientations. During the flare, the fractional linear POLARIZATION is explained by the turbulent emission multi-zone model.

[abstract 3 / 36] Wow! (score: 9)
arXiv:2607.19972 [pdf, ps, other]

Title: Constraints on the VHE counterpart of two binary BLACK HOLE mergers observed by the MAGIC and CTAO LST-1 telescopes

Authors: K. Abe, S. Abe, J. Abhir, A. Abhishek, V. A. Acciari, F. Acero, A. Aguasca-Cabot, I. Agudo, I. Albanese, D. Ambrosino, F. Ambrosino, T. Aniello, S. Ansoldi, L. A. Antonelli, C. Aramo, C. Arauner, A. Arbet-Engels, C. Arcaro, T. T. H. Arnesen, P. Aubert, A. Babić, C. Bakshi, A. Baktash, M. Balbo, A. Bamba, A. Baquero Larriva, U. Barres de Almeida, J. A. Barrio, L. Barrios Jiménez, I. Batkovic, J. Baxter, J. Becerra González, W. Bednarek, E. Bernardini, J. Bernete, A. Berti, J. Besenrieder, C. Bigongiari, A. Biland, E. Bissaldi, O. Blanch, Ž, . Bošnjak, G. Bonnoli, P. Bordas, L. Breton-Zaourat, A. Briscioli, E. Bronzini, G. Brunelli, J. Buces, A. Bulgarelli, I. Burelli, L. Burmistrov, C. Campa, A. Campoy-Ordaz, M. Cardillo, S. Caroff, A. Carosi, R. Carosi, R. Carraro, M. Carretero-Castrillo, F. Cassol, A. J. Castro-Tirado, D. Cerasole, G. Ceribella, A. Cerviño Cortínez, Y. Chai, A. Chiavassa, A. Chilingarian, G. Chon, L. Chytka, G. M. Cicciari, A. Cifuentes Santos, J. L. Contreras, J. Cortina, H. Costantini, S. Covino, M. Croisonnier, G. D'Amico, P. Da Vela, M. Dalchenko, F. Dazzi, A. De Angelis, M. de Bony de Lavergne, B. De Lotto, R. de Menezes, G. De Palma, V. de Souza, R. Del Burgo, L. Del Peral, M. Delfino, C. Delgado Mendez, J. Delgado Mengual, D. della Volpe, L. Di Bella, C. Di Domenico, A. Di Piano, F. Di Pierro, R. Di Tria, L. Di Venere, C. Díaz, A. Dinesh, E. Do Souto Espi\ neira, D. Dominis Prester, A. Donini, D. Dorner, M. Doro, L. Eisenberger, D. Elsässer, G. Emery, J. Escudero, L. Fari\ na, L. Feligioni, F. Ferrarotto, A. Fiasson, L. Foffano, L. Font, F. Frías García-Lago, Y. Fukazawa, S. Gallozzi, J. Garcia Garcia, R. J. García López, S. Garcia Soto, D. Gasparrini, S. Gasparyan, M. Gaug, J. G. Giesbrecht Paiva, N. Giglietto, F. Giordano, P. Gliwny, N. Godinovic, T. Gradetzke, R. Grau, J. Green, G. Grolleron, S. Gunji, P. Günther, D. Hadasch, A. Hahn, M. Hashizume, T. Hassan, K. Hayashi, L. Heckmann, M. Heller, J. Herrera Llorente, N. Hiroshima, D. Hoffmann, D. Horns, J. Houles, D. Hrupec, T. Inada, S. Inoue, K. Ioka, M. Iori, D. Israyelyan, A. Iuliano, J. Jahanvi, I. Jiménez Martínez, J. Jiménez Quiles I. Jorge Rodrigo, J. Jurysek, M. Kagaya, S. Kankkunen, V. Karas, H. Katagiri, T. Kayanoki, D. Kerszberg, M. Khachatryan, G. W. Kluge, Y. Kobayashi, K. Kohri, J. Konrad, P. Kornecki, P. M. Kouch, H. Kubo, J. Kushida, B. Lacave, M. Láinez, A. Lamastra, L. Lemoigne, E. Lindfors, M. Linhoff, S. Lombardi, F. Longo, R. López-Coto, M. López-Moya, A. López-Oramas, S. Loporchio, A. Lorini, J. Lozano Bahilo, F. Lucarelli, H. Luciani, L. Lulić, P. L. Luque-Escamilla, P. Majumdar, M. Makariev, M. Mallamaci, D. Mandat, G. Maneva, M. Manganaro, S. Mangano, D. K. Maniadakis, G. Manicò, K. Mannheim, F. Marini, M. Mariotti, G. Marsella, J. Martí, D. Martin, G. Martínez, M. Martínez, O. Martinez, P. Maruš, evec, M. Massa, D. Mazin, S. Menchiari, J. Méndez-Gallego, S. Menon, E. Mestre Guillen, D. Miceli, T. Miener, J. M. Miranda, J. M. Miranda, R. Mirzoyan, M. Mizuno, M. Molero Gonzalez, E. Molina, H. A. Mondal, T. Montaruli, A. Moralejo, S. Morales Sanchez De Lozada, K. Morita, A. Morselli, V. Moya, K. Mrakovčić, A. L. Müller, H. Muraishi, T. Nagata, S. Nagataki, T. Nakamori, C. Nanci, A. Negro, A. Neronov, V. Neustroev, D. Nieto Castaño, M. Nievas Rosillo, C. Nigro, L. Nikolić, K. Nilsson, K. Noda, V. Novotny, S. Nozaki, M. Ohishi, A. Okumura, R. Orito, L. Orsini, J. Otero-Santos, P. Ottanelli, S. Paiano, M. Palatiello, G. Panebianco, D. Paneque, R. Paoletti, J. M. Paredes, M. Pech, M. Pecimotika M. Peresano, F. Perrotta, M. Persic, F. Pfeifle, E. Pietropaolo, M. Pihet, G. Pirola, C. Plard, F. Podobnik, M. Polo, C. Pozo-Gonzaléz, P. G. Prada Moroni, E. Prandini, S. Rainò, R. Rando, W. Rhode, M. Ribó, J. Rico, V. Rizi, G. Rodriguez Fernandez, A. Roy, E. Ruiz-Velasco, N. Sahakyan, T. Saito, S. Sakurai, D. A. Sanchez, H. Sano, E. Santos Moura, T. Šarić, Y. Sato, F. G. Saturni, V. Savchenko, F. Schiavone, K. Schmitz, F. Schussler, T. Schweizer, M. Seglar Arroyo U. Sharma, T. Siegert, G. Silvestri, A. Simongini J. Sitarek, V. Sliusar, D. Sobczynska, I. Sofia, A. Stamerra, J. Strišković, D. Strom, M. Strzys, Y. Suda, A. Sunny, H. Tajima, M. Takahashi, R. Takeishi, S. J. Tanaka, J. Tartera Barberà, T. Tavernier, P. Temnikov, Y. Terada, K. Terauchi, T. Terzic, M. Teshima, M. Tluczykont, T. Tomura, D. F. Torres, F. Tramonti, P. Travnicek, G. Tripodo, A. Tutone, S. Ubach, M. Vacula, M. Vázquez Acosta, S. Ventura, G. Verna, I. Viale, A. Viana, A. Vigliano, C. F. Vigorito, E. Visentin, V. Vitale, M. Vorbrugg, G. Voutsinas, I. Vovk, T. Vuillaume, R. Walter, C. Walther, L. Wan, P. Witczak, F. Wersig, T. Yamamoto, R. Yamazaki, Y. Yao, P. K. H. Yeung, T. Yoshida, T. Yoshikoshi, W. Zhang,

Comments: In press at PASP. Corresponding authors: Andrea Simongini, Juan Jiménez Quiles, Mario Pecimotika, Monica Seglar-Arroyo

Subjects: astro-ph.HE

Created: 2026-07-22; Updated: 2026-07-23; Datestamp: 2026-07-23

We present very-high-energy gamma-ray observations of two binary BLACK HOLE merger candidates, GW240615_113620 and GW241125_010116, performed with the Major Atmospheric Gamma Imaging Cherenkov (MAGIC) telescopes and the first Large-Sized Telescope of the Cherenkov Telescope Array Observatory's (CTAO LST-1). GW240615_113620 was the best localized event of the fourth observing run of the LIGO-Virgo-KAGRA gravitational waves interferometers. GW241125_010116 was temporally and spatially coincident with a sub-threshold short-duration burst detected with the SWIFT-Burst Alert Telescope (BAT), the SWIFT-X-Ray Telescope (XRT) and the Einstein Probe Follow-up X-ray Telescope (FXT). We observed the two events in stereoscopic mode, taking advantage of the improved sensitivity of joint MAGIC+LST-1 observations. No detection was achieved in the GeV-TeV gamma-ray band for any of the two sources. The unfavourable observing conditions of both events posed a challenge for a standard analysis and therefore a non standard analysis was necessary for both objects. Owing to the small localization area and the association with a GRB-like burst respectively, these events represented an unprecedented opportunity to study in details the electroMAGNETic emission from binary BLACK HOLEs merger events and, in particular, we discussed two theoretical models that predict a detectable gamma-ray emission and the possible future applications.

[abstract 4 / 36] Wow! (score: 8)
arXiv:2606.10527 [pdf, ps, other]

Title: Circular POLARIZATION effects induced by photon-axion mixing in astrophysical environments

Authors: Meng Wang, Nan Ding, Qiusheng Gu, Yunyong Tang, Rui Xue,

Comments: 15 pages, 7 figures. Accepted for publication in Physical Review D

Subjects: astro-ph.HE

Created: 2026-07-22; Updated: 2026-07-23; Datestamp: 2026-07-23

Axions and axion-like particles (ALPs) are compelling candidates for DARK MATTER and new physics beyond the Standard Model. Photon-axion mixing in external MAGNETic fields modifies the photon energy spectrum and linear POLARIZATION state, and also induces circular POLARIZATION signals. Compared to spectral and linear POLARIZATION methods, circular POLARIZATION benefits from lower astrophysical background contamination, providing an independent probe for axion searches. In this work, we study the circular POLARIZATION induced by photon-axion mixing within the chiral basis framework. By analytically solving the evolution equations under the single-domain approximation, we derive an expression for the circular POLARIZATION degree $P_C$, applicable in the resonant, strong coupling, and weak coupling regimes. Within single-domain MAGNETic field models, we compare the energy-dependent circular POLARIZATION in four astrophysical environments (AGN JETs, intracluster medium, intergalactic medium, and Galactic MAGNETic fields). We find that the X-ray to MeV band represents the most sensitive observational window. Using the BLAZAR S4 0954+65 as a case study, phase accumulation in random MAGNETic domains causes the circular POLARIZATION degree to fluctuate with redshift and exhibit pronounced energy structures. Using the optical circular POLARIZATION upper limit $P_C < 0.184\%$ (measured in the z-SDSS band) from this source, we statistically constrain $g_{aγγ} \lesssim 3\times 10^{-11}\,\mathrm{GeV}^{-1}$ (95\% confidence level) for $m_a \sim 10^{-16}$--$10^{-10}\ \mathrm{eV}$, with the strongest constraint reaching $g_{aγγ}\sim6\times10^{-12}\,\mathrm{GeV}^{-1}$ near $m_a \sim 10^{-14}\,\mathrm{eV}$. These results establish circular POLARIZATION as a complementary axion probe.

[abstract 5 / 36] Wow! (score: 7)
arXiv:2607.20209 [pdf, ps, other]

Title: Shock acceleration in vortex driven MAGNETic fields of BLACK HOLEs

Authors: Zaza N. Osmanov,

Comments: 5 pages, 2 figures

Subjects: astro-ph.HE

Created: 2026-07-22; Updated: 2026-07-23; Datestamp: 2026-07-23

The aim of this work is to investigate particle acceleration by shock waves in the MAGNETospheres of supermassive BLACK HOLEs, where the MAGNETic field is vortex-driven. For this purpose, we investigated the first-order FERMI acceleration process at RELATIVISTIC shocks in the MAGNETospheres of supermassive BLACK HOLEs. In our analysis, we considered SYNCHROTRON radiation and inverse Compton scattering as the principal energy-loss mechanisms limiting the maximum attainable particle energy. We investigated the acceleration of both protons and electrons and demonstrated that, for a typical supermassive BLACK HOLE with a mass of $10^8$ solar masses, protons can be accelerated to energies of several hundred PeV, whereas electrons can attain energies of up to approximately 120 GeV.

[abstract 6 / 36] Yes (score: 5)
arXiv:2408.16748 [pdf, ps, other]

Title: Non-detection of Neutrinos from the BOAT: Improved Constraints on the Parameters of GRB 221009A

Authors: P. Veres, N. Fraija, S. Lesage, A. Goldstein, M. S. Briggs, P. N. Bhat,

Comments: 11 pages, 3 figures, 1 table. Minor revision: corrected notation, typos. Accepted in ApJ

Subjects: astro-ph.HE

Created: 2026-07-22; Updated: 2026-07-23; Datestamp: 2026-07-23

The IceCube neutrino observatory detects the diffuse astrophysical neutrino background with high significance, but the contribution of different classes of sources is not established. Because of their non-thermal spectrum, GAMMA-RAY BURSTs (GRBs) are prime particle acceleration sites and one of the candidate classes for significant neutrino production. Exhaustive searches, based on stacking analysis of GRBs however could not establish the link between neutrinos and GRBs. Gamma-ray burst GRB 221009A had the highest time integrated gamma-ray flux of any detected GRB so far. The total fluence exceeds the sum of all FERMI Gamma-ray Burst Monitor (GBM) detected GRBs by a factor of two. Because it happened relatively nearby, it is one of the most favorable events for neutrino production from GRBs yet no neutrinos were detected. We calculate neutrino fluxes for this GRB in the TeV-PeV range using the most accurate, time-resolved spectral data covering the brightest intervals. We place limits on the physical parameters (Lorentz factor, baryon loading or emission radius) of the burst that are better by a factor of 2 compared to previous limits. The neutrino non-detection indicates a bulk Lorentz factor greater than 500 and possibly even 800, consistent with other observations.

[abstract 7 / 36] Yes (score: 5)
arXiv:2512.19403 [pdf, ps, other]

Title: Diagnosing the AGN population origin of TeV neutrinos with their spatial correlation

Authors: Xiao-Bin Chen, Ruo-Yu Liu, Xiang-Yu Wang,

Comments: Accepted for publication in The Astrophysical Journal

Subjects: astro-ph.HE

Created: 2026-07-22; Updated: 2026-07-23; Datestamp: 2026-07-23

The recent detection of TeV neutrinos from nearby Seyfert galaxies (e.g., NGC 1068) by IceCube suggests that ACTIVE GALACTIC NUCLEi (AGNs) could make a significant contribution to diffuse astrophysical neutrinos. The absence of TeV gamma-rays from NGC 1068 indicates neutrino production in a compact opaque region of gamma-rays. The vicinity of the supermassive BLACK HOLE, such as the disk-corona, is an ideal region, where the high radiation density leads to efficient neutrino production and gamma-ray attenuation. Disk-corona models predict that the neutrino emission from AGNs correlates with X-ray emission, which traces the coronal activity. In this paper, we assess whether diffuse TeV neutrinos can originate from X-ray-emitting AGNs with Monte Carlo simulations, considering the predicted performance of future neutrino telescopes. We test this hypothesis by searching for spatial correlations between the X-ray AGN population and high-energy neutrinos, assuming that the neutrino flux scales with the AGN X-ray flux. After accounting for the fraction of the AGN X-ray flux resolved by eFEDS and the remaining unresolved AGN component, we find that an AGN origin of diffuse neutrinos can be tested at a significance of about $3σ$ with ten years of IceCube-Gen2 observations. With improved angular resolution and sensitivity, a 30\,km$^{3}$-scale underwater neutrino telescope such as HUNT is expected to reach a significance of about $6σ$ with one year of exposure. The detection significance decreases if AGNs contribute partially to the total astrophysical neutrino flux. Our results highlight the critical role of angular resolution in diagnosing the AGN origin of diffuse TeV neutrinos.

[abstract 8 / 36] Yes (score: 5)
arXiv:2604.10629 [pdf, ps, other]

Title: Searching for Gamma Ray Bursts associated with CHIME Fast Radio bursts

Authors: Yi-Fang Liang, Ye Li, Bao Wang, Xuan Yang, Yuan-Pei Yang, Xue-Feng Wu,

Comments: 16 pages, 4 figures, 1 table, accepted for publication in ApJ

Subjects: astro-ph.HE

Created: 2026-07-22; Updated: 2026-07-23; Datestamp: 2026-07-23

Fast radio bursts (FRBs) and GAMMA-RAY BURSTs (GRBs) are both linked to compact-object activity, yet their possible connection remains unclear. Here we perform a systematic search for spatial and temporal associations between FRBs in the second CHIME/FRB catalog and SWIFT GRBs. Instead of using the positional ellipses reported in the catalog, the full CHIME localization probability maps are adopted for spatial cross-matching. This yields 130 candidate pairs and increases the number of spatially consistent matches by a factor of several. Applying a distance-consistency criterion based on DM-inferred FRB redshifts and GRB distances inferred via the Amati relation reduces the sample to 37 pairs, including 26 GRB-preceding-FRB candidates (24 LGRB--FRB and 2 SGRB--FRB). Monte Carlo simulations show that the overall excess of associations is not statistically significant, and the distribution of matches across localization confidence levels is consistent with random expectations. These pairs are therefore not claimed as secure associations, but are used to constrain a possible subdominant FRB--GRB connection. These results place constraints on any FRB--GRB connection and highlight the need for improved localization and larger samples.

[abstract 9 / 36] Yes (score: 4)
arXiv:2604.13650 [pdf, ps, other]

Title: Prospects for GRB Afterglow Discovery with the Eric and Wendy Schmidt Observatory System

Authors: James Freeburn, Dougal Dobie, Akash Anumarlapudi, Igor Andreoni, Brendan O'Connor, Eric Burns, Jonathan Carney, Hank Corbett, Michael W. Coughlin, Adam Goldstein, Anna Tartaglia, V. Ashley Villar,

Comments: 22 pages, 9 figures, 6 tables, accepted for publication in ApJ

Subjects: astro-ph.HE

Created: 2026-07-22; Updated: 2026-07-23; Datestamp: 2026-07-23

Two time domain surveys, recently funded as part of the Eric and Wendy Schmidt Observatory System; the Argus Array, in the optical, and the Deep Synoptic Array (DSA), in the radio, will transform GAMMA-RAY BURST (GRB) science via the serendipitous discovery of hundreds of GRB afterglows per year. In this work, we simulate DSA and Argus observations of GRB afterglows. We find that, of the long-duration GRBs (LGRBs) detected by the FERMI Gamma-ray Burst Monitor, (26$\pm$3)% will yield afterglow detections with Argus and (44$\pm$3)% with DSA, corresponding to rates of 51$\pm$5 and 86$\pm$8 per year respectively. We also compute rates for both upcoming and proposed GRB monitors; the forthcoming StarBurst Multi-messenger Pioneer, with 84$\pm$6 detections per year in Argus and 158$\pm$11 detections per year in DSA, and the Moon Burst Energetics All-sky Monitor (MoonBEAM) concept, with 90$\pm$9 per year in Argus and 160$\pm$14 per year in DSA. The observatory system will also detect 118$\pm$10 optical and 199$\pm$17 radio afterglows per year, independent of GRB triggers, exceeding the current annual rate with global follow-up. Afterglow counterparts to short-duration GRBs, originating from neutron star mergers, will be detected at 5-10% of the LGRB afterglow rate, which is promising for multi-messenger detections of gravitational wave sources and constraining the neutron star merger rate. The Argus Array, with its second-minute cadence, will detect afterglows before they peak $\sim$18% of the time, which will dramatically increase the sample of observed reverse shock and prompt optical emission.

[abstract 10 / 36] Yes (score: 4)
arXiv:2606.00209 [pdf, ps, other]

Title: On the Faint Early-time Radio and X-ray Emissions in TDE2025aarm

Authors: Tatsuya Matsumoto, Tsvi Piran,

Comments: 8 pages, 4 figures, accepted version, updated references

Subjects: astro-ph.HE

Created: 2026-07-22; Updated: 2026-07-23; Datestamp: 2026-07-23

TDE2025aarm is a nearby tidal disruption event whose early radio and X-ray emissions are exceptionally faint compared with previously observed TDEs. We examine whether these weak signals can be explained within standard outflow and disk-emission scenarios. The radio detection at $15\,\rm GHz$ with $\sim10^{36}\,\rm erg\,s^{-1}$ around $40\,\rm days$ after discovery is inconsistent with SYNCHROTRON emission from a quasi-spherical disk wind for reasonable circum-nuclear densities and outflow velocities. Instead, the low luminosity and inferred self-absorbed spectrum imply a narrowly collimated outflow with a solid angle $\lesssim0.1\,\rm sr$, naturally identified with the unbound stellar debris. The X-ray emission is likewise unusually faint, with $L_{\rm X}\sim10^{39-40}\,\rm erg\,s^{-1}$ during the first few months. If interpreted as thermal emission from an obscured accretion disk, the inferred emitting area would correspond to an implausibly small X-ray-transparent region expected to vary on short dynamical timescales that are not observed. Alternatively, the same shock responsible for the radio emission can accelerate RELATIVISTIC electrons that produce X-rays through SYNCHROTRON radiation and/or inverse-Compton scattering of optical/UV photons. Both mechanisms can explain the early faint X-ray emission, although their temporal evolution differs. Continued radio and X-ray monitoring of TDE2025aarm will provide a sensitive probe of the unbound debris, circum-nuclear medium, and high-energy emission mechanisms in optical TDEs.

[abstract 11 / 36] Yes (score: 4)
arXiv:2607.19485 [pdf, ps, other]

Title: Extreme Variability Reveals How the Eddington Ratio Regulates Coronal Power in Active Galactic Nuclei

Authors: Arghajit Jana, Claudio Ricci, Franz E. Bauer, Kriti Kamal Gupta, Benny Trakhtenbrot, Alessia Tortosa, Ruancun Li, Luis C. Ho, Richard Mushotzky, Hsiang-Kuang Chang, Yaherlyn Diaz, Georgios Dimopoulos, Kristína Kallová, Michael J. Koss, Stéphane Paltani, Matthew J. Temple,

Comments: 4 figures, accepted for publication in ApJ Letter. Comments are welcome

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

Created: 2026-07-21; Updated: 2026-07-23; Datestamp: 2026-07-23

The bolometric luminosity ($L_{\rm bol}$) of ACTIVE GALACTIC NUCLEi (AGNs) is a key tracer of accretion physics, but its direct determination is often hindered by limited spectral coverage and contamination of the host galaxy. Bolometric corrections ($κ_λ = L_{\rm bol}/L_λ$) offer a practical means of estimating $L_{\rm bol}$, with the X-ray bolometric correction ($κ_{\rm 2-10}$) being crucial for exploring the coupling between the accretion disk and the X-ray corona. Here we present multi-epoch, multi-wavelength observations of five highly variable, changing-state AGNs that span more than three orders of magnitude in Eddington ratio ($-3.6\lesssim \log λ_{\rm Edd} \lesssim -0.5$). This unique data set reveals a remarkably tight relation between $κ_{\rm 2-10}$ and $λ_{\rm Edd}$, with an intrinsic scatter of only $\sim0.05$ dex. We find that while the sources show bolometric corrections following different tracks in luminosity space that depend on BLACK HOLE mass, they all display the same $κ_{\rm 2-10}-λ_{\rm Edd}$ trend. This shows unambiguously that $λ_{\rm Edd}$ is the primary driver of X-ray bolometric corrections, and points to a tight underlying trend that can be used to obtain reliable estimates of bolometric output from X-ray luminosities. Our results highlight how time-domain, multi-wavelength observations of variable AGN offer unique insights into the accretion flow structure and its radiative output.

[abstract 12 / 36] Yes (score: 4)
arXiv:2607.19491 [pdf, ps, other]

Title: Rapid growth in a dual AGN during a gas-rich merger at z~4.5

Authors: Hyewon Suh, Roberto Decarli, Emanuele Paolo Farina, Julia Scharwächter, Mar Mezcua, Giorgio Lanzuisi, Federica Loiacono, Brian C. Lemaux, Sukyoung K. Yi, Stefano Marchesi, Marta Volonteri, Günther Hasinger, Francesca Civano, Anniek Gloudemans, Ena Choi, Yeonwoo Nam, Adi Foord, Silvia Onorato,

Comments: Nat. Astron. accepted

Subjects: astro-ph.GA

Created: 2026-07-21; Updated: 2026-07-23; Datestamp: 2026-07-23

The late stages of galaxy mergers - when two supermassive BLACK HOLEs (SMBHs) reach kiloparsec-scale separations - represent a critical phase for understanding SMBH growth, galaxy co-evolution, and the progenitors of low-frequency gravitational waves. Yet confirmed close-separation (<3 kpc) dual ACTIVE GALACTIC NUCLEi (AGNs) remain confined to the local Universe, despite predictions that such systems should be common in the merger-rich early Universe. Here we report the discovery of LID-1166, a dual AGN with a projected separation of ~1.5 kpc at z~4.5, representing the first such system known beyond the local Universe. Spatially resolved JWST/NIRSpec integral-field spectroscopy reveals two spatially and kinematically distinct narrow-line emission components with a line-of-sight velocity offset of ~ -164 km/s. Both components additionally exhibit broad Ha emission, including a compact off-nuclei broad Ha component associated with the companion source, confirming two actively accreting SMBHs. Independent ALMA [CII] 158 um observations reveal corresponding spatially and kinematically distinct cold gas components associated with the same nuclei, demonstrating that the system is a gas-rich merger. While undergoing super-Eddington accretion during a late-stage merger, the SMBHs already lie on the local BLACK HOLE-host mass relation for massive elliptical galaxies within the uncertainties, suggesting that rapid, obscured growth may help establish this relation early in cosmic history. LID-1166 reveals a previously hidden phase of SMBH growth and points to a missing population of heavily obscured, merger-driven dual AGNs at high redshift.

[abstract 13 / 36] Yes (score: 4)
arXiv:2607.19529 [pdf, ps, other]

Title: Discovery of Optical Filaments in the North Polar Spur/eROSITA Bubble

Authors: Julian Shapiro,

Comments: 10 pages, 4 figures, submitted to ApJL, comments welcome

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

Created: 2026-07-21; Updated: 2026-07-23; Datestamp: 2026-07-23

I report the discovery of optical filaments in H$α$, [O III], and [S II], coincident with $144\,\mathrm{MHz}$ structure, associated with the North Polar Spur (NPS) region of the eROSITA bubbles. The optical emission is identified in the Northern Sky Narrowband Survey, and contains distinct structure and potentially elevated $\text{[S II]}/\mathrm{H}α$ relative to typical high-$b$ outflows from the warm ionized medium (WIM). $Δ$-variance and power spectrum analysis of the NPS H$α$ shows a preference for filaments on the scale of lag $L\approx0.6^{\circ}$. The optical and $144\,\mathrm{MHz}$ emission peaks in intensity in an interior region of the NPS, aligned with surrounding Galactic MAGNETized structures, and also shows fainter signal at the eROSITA bubble edge. The required power to produce the background-subtracted $I_{\mathrm{H}α}=1.85\pm1.04\,\mathrm{R}$ emission is $P_\mathrm{req}\approx5\mathrm{-}12\times10^{41}\,\mathrm{erg\,s}^{-1}$, comfortably exceeded by AGN JET models, plausible for AGN hot accretion flow and STAR FORMATION ring models, and disfavoring STAR FORMATION driven winds.

[abstract 14 / 36] (score: 3)
arXiv:2504.00075 [pdf, ps, other]

Title: Massive Black Holes Seeded by Dark Matter -- Implications for Little Red Dots and Gravitational Wave Signatures

Authors: Tingwei Shen, Xuejian Shen, Huangyu Xiao, Mark Vogelsberger, Fangzhou Jiang,

Comments: Accepted by PRD

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

Created: 2026-07-21; Updated: 2026-07-23; Datestamp: 2026-07-23

Observations of supermassive BLACK HOLEs (SMBHs) at high redshifts challenge standard seeding scenarios. We examine a dissipative self-interacting DARK MATTER (dSIDM) model in which gravothermal collapse leads to the formation of massive BH seeds ab initio. We utilize a semi-analytical framework to predict properties of the dSIDM-seeded SMBH population. Billion solar mass QUASARs are reproduced along with low-mass faint ACTIVE GALACTIC NUCLEi (known as little red dots) with SMBH-to-galaxy stellar mass ratios consistent with recent James Webb Space Telescope observations. To match the abundance of the observed bright QUASARs, a percent-level duty-cycle is suggested, implying a large population of dormant SMBHs. The gravitational wave (GW) signals from mergers of these massive SMBHs can be detected by LISA while remaining within the NANOGrav constraints on the GW background. These results provide testable signatures of DM-driven SMBH formation, offering a pathway to probe hidden-sector physics through SMBH and GW observables.

[abstract 15 / 36] (score: 3)
arXiv:2512.08003 [pdf, ps, other]

Title: Quadrupole spectra derived from 2.76 TeV Pb-Pb identified-hadron $\bf v_2(p_t)$ data

Authors: Thomas A. Trainor,

Comments: 23 pages, 20 figures, response to further referee comments. arXiv admin note: text overlap with arXiv:1610.06256 -- 1610.06256 provides introductory material for this article

Subjects: hep-ph

Created: 2026-07-22; Updated: 2026-07-23; Datestamp: 2026-07-23

$p_t$-differential quantity $v_2(p_t)$ is meant to measure elliptic flow manifested by a dense QCD medium formed in high-energy nucleus-nucleus collisions. Elliptic flow may be referred to more neutrally as a cylindrical quadrupole component of the transverse motion of particle sources within a collision. As defined, $v_2(p_t)$ relies on an implicit assumption that almost all produced particles emerge from a single source. This article describes a detailed study of the algebraic structure of $v_2(p_t)$. A procedure is developed to derive a common monopole boost (radial flow) value and quadrupole $p_t$ spectra for several hadron species. The method is applied to $v_2(p_t)$ data for three hadron species from 2.76 TeV Pb-Pb collisions. According to available $v_2(p_t)$ data the assumption of a single dominant particle source within A-A collisions is unjustified. Combined with a previous study of quadrupole amplitude variation for 200 GeV $p$-$p$ collisions these results demonstrate that quadrupole structure is related to a novel QCD process separate from projectile-nucleon dissociation and JET production. Given quadrupole evolution it is unlikely that a hydrodynamic description is relevant to that process.

[abstract 16 / 36] (score: 3)
arXiv:2512.09017 [pdf, ps, other]

Title: Viscously Spreading Accretion Disks around Black Holes: Implications for TDEs, LFBOTs and other Transients

Authors: Mila Winter-Granic, Eliot Quataert,

Comments: 17 pages, 11 figures. Published The Open Journal of Astrophysics

Subjects: astro-ph.HE

Created: 2026-07-22; Updated: 2026-07-23; Datestamp: 2026-07-23

We present a simple time-dependent model of viscously spreading accretion disks around BLACK HOLEs (BHs) with masses between $10-10^8M_\odot$. We apply the results to observations of late-time emission in tidal disruption events (TDEs) and luminous fast blue optical transients (LFBOT) such as AT2018cow. Our model generalizes previous work by incorporating outflows during super-Eddington accretion, non-conservation of mass and angular momentum in TDE circularization, irradiation of the outer disk by the inner accretion flow, and a range of viscous stress models. We show that many late-time plateaus in TDEs can be explained by disks formed with a large spread in angular momentum due to redistribution during circularization. Viscous spreading on year timescales is not required, although it is also compatible with the data. The collapse of radiation pressure dominated thin disks to the stable gas-pressure dominated phase greatly underpredicts TDE plateau luminosities, strongly favoring thermally stable MAGNETically dominated disk models. Irradiation of the outer disk in TDEs due to misalignment of the stellar orbit and BLACK HOLE spin increases plateau luminosities and durations by factors of a few. Continued study of late-time TDE emission provides a unique opportunity to constrain the physics of disk formation and circularization, disk warps, angular momentum transport, and other poorly understood aspects of disk physics. The models we develop can also explain the late-time optical-UV emission in the LFBOT AT2018cow for BH masses of ~$10-100M_\odot$. The faint X-ray emission at late times in AT2018cow is likely due to ongoing absorption. Our models predict that late-time X-rays should eventually be detectable again, and that HST/JWST observations of AT2018cow may detect a break in the SED at near-IR-optical wavelengths, providing a powerful probe of outer accretion disk thermodynamics.

[abstract 17 / 36] (score: 3)
arXiv:2512.22764 [pdf, ps, other]

Title: Polarized image of an equatorial emitting ring around a Konoplya-Zhidenko rotating non-Kerr BLACK HOLE

Authors: Xin Qin, Fen Long, Songbai Chen, Jiliang Jing,

Comments: Accepted by Chinese Physics C; 8 figures

Subjects: gr-qc

Created: 2026-07-22; Updated: 2026-07-23; Datestamp: 2026-07-23

We investigate the polarized images of an equatorial emitting ring around a Konoplya-Zhidenko rotating non-Kerr BLACK HOLE, which introduces an additional deformation parameter. The deformation parameter $η$ allows the spin parameter to extend beyond the bounds imposed by the standard Kerr BLACK HOLE. The results indicate that the polarized images depend not only on the MAGNETic field configuration, fluid velocity, and observer inclination angle, but also on the deformation parameter and the spin parameter. As the deformation parameter increases, the POLARIZATION intensity decreases monotonically. However, the magnitude of the Electric Vector Position Angle (EVPA) increases with $η$. Furthermore, we note that the parameter $η$ may induce subtle yet discernible azimuthal separation features, which could potentially distinguish it from the spin parameter and the MAGNETic field orientation angle. Nevertheless, these features are difficult to resolve under current observational conditions and await verification by future high-resolution facilities such as the next-generation Event Horizon Telescope (ngEHT).

[abstract 18 / 36] (score: 3)
arXiv:2606.14643 [pdf, ps, other]

Title: Nebular_AGN: A CIGALE module for fitting AGN emission lines

Authors: Hao Zhang, Patrice Theule, Veronique Buat, Denis Burgarella, Estelle Pons, Mederic Boquien,

Comments:

Subjects: astro-ph.GA

Created: 2026-07-22; Updated: 2026-07-23; Datestamp: 2026-07-23

Aims. The increasing discovery of high-redshift AGNs in recent years imposes more stringent requirements on spectral analysis tools for deriving the properties of AGNs and their host galaxies from emission-line diagnostics. To address this need, we develop a new module for the popular SED-fitting tool Code Investigating GALaxy Emission (CIGALE), the [nebular_AGN] module, which enables the efficient and flexible simulation and fitting of emission lines originating from the broad-line regions (BLRs) and narrow-line regions (NLRs) of AGNs, and allows the estimation of the physical properties of these regions. Methods. We use the spectral synthesis code Cloudy to construct the database for the new module. Based on the X-ray and accretion disk continua implemented in CIGALE, we generate the incident radiation fields of the models. We then adopt the AGN geometry and dust settings implemented in CIGALE to define a flexible set of physical parameters for the gas clouds, thereby producing a comprehensive database for the [nebular_AGN] module. Results. We benchmark the [nebular_AGN] module using a QUASAR composite spectrum, an empirical metallicity calibration, and observational data from X-ray-selected AGNs. Our module can approximately reproduce the majority of QUASAR emission-line profiles, cover the key emission-line ratios observed in AGN samples, and provide an assessment of their physical properties. For specific combinations of parameters, the metallicity derived by our module is consistent with the empirical formula. We further compare our models with other photoionization models used to simulate AGN NLR emission, and perform a line-sensitivity study to identify the most effective diagnostic lines for each parameter in our module. Finally, we confirm that the dust attenuation law plays an important role in SED fitting.

[abstract 19 / 36] (score: 3)
arXiv:2606.31289 [pdf, ps, other]

Title: Multi-band power color-color diagrams of three BLACK HOLE X-ray binaries observed with Insight-HXMT

Authors: Shao-Feng Liu, Long Ji, Yanan Wang,

Comments:

Subjects: astro-ph.HE

Created: 2026-07-22; Updated: 2026-07-23; Datestamp: 2026-07-23

Power color-color diagrams (PCCDs) provide a useful diagnostic tool for studying the evolution of outbursts in BLACK HOLE X-ray binaries. In this paper, we present power color-color diagrams of three sources (MAXI J1348-630, MAXI J1820+070 and SWIFT J1727.8-1613) observed with Insight-HXMT in a wide energy range of 2-80 keV. We compared the hue regions defined by RXTE, which are associated with different spectral states, with the Insight-HXMT results. We find that, for hard and hard-intermediate states, the trajectories of Insight-HXMT in the power color-color diagrams are generally consistent with those of RXTE. In the soft and soft-intermediate states, weak variability generally prevents robust hue constraints. Nevertheless, a few points in MAXI J1348-630 deviate from the RXTE-defined regions, possibly because of averaged variable power spectra and the presence of a type-A QPO. The trajectories of MAXI J1348-630 and MAXI J1820+070 exhibited roughly consistent patterns over different energy bands, whereas SWIFT J1727.8-1613 was an exception during its very high state, caused by an additional low-frequency component in the low-energy band. We found that the very high state can be identified through the power color-color diagram, exhibiting a hue similar to that of the hard-intermediate state but not forming a loop pattern. We also investigated the relationship between hue and hardness and found that, although they are generally anti-correlated, they provide consistent timing for the spectral state transitions.

[abstract 20 / 36] (score: 3)
arXiv:2607.17887 [pdf, ps, other]

Title: Angular momentum flux through post-Newtonian order for noncircular nonspinning black-hole binaries in Einstein-Maxwell-dilaton theory

Authors: Qi Tan, Peng-Cheng Li,

Comments: 26 pages, 1 figure; updated bibliography and related-work discussion; results unchanged

Subjects: gr-qc

Created: 2026-07-22; Updated: 2026-07-23; Datestamp: 2026-07-23

We compute the instantaneous angular momentum flux from nonspinning BLACK HOLE binaries in Einstein-Maxwell-dilaton theory for generic noncircular orbits up to relative first post-Newtonian order. Working in the Einstein frame and using the direct integration of the relaxed field equations approach, we construct the scalar, electroMAGNETic, and tensor gravitational fields in the wave zone and express the required source multipole moments in the center-of-mass frame. In addition to the leading $1/R$ radiative fields, we retain the next-to-leading $1/R^2$ terms in the wave-zone fields, which describe finite-distance corrections and do not contribute to the flux at null infinity. We obtain separately the scalar, electroMAGNETic, and tensor contributions to the angular momentum flux. The scalar and electroMAGNETic channels begin with dipole radiation, while the tensor channel begins at quadrupole order. Our results recover the quasicircular balance relation, the known general-RELATIVISTIC limit, and the expected scalar- and electroMAGNETic-dipole suppression limits. Together with the previously known energy flux, these results provide the dissipative information required for future studies of orbit-averaged eccentric evolution and waveform phasing in Einstein-Maxwell-dilaton theory.

[abstract 21 / 36] (score: 3)
arXiv:2607.19428 [pdf, ps, other]

Title: Clarifying Dead Quasars and Downsizing through the Evolution of Star-Forming Galaxies and Active Galactic Nuclei

Authors: Shingo Sumie,

Comments: 13 pages, 15 figures, 1 table

Subjects: astro-ph.GA

Created: 2026-07-20; Updated: 2026-07-23; Datestamp: 2026-07-23

From the catalogs of visible emission lines of galaxies measured by the Subaru Fiber Multi-Object Spectrograph (Subaru-FMOS) and the KECK Multi-Object Spectrograph For InfraRed Exploration (KECK-MOSFIRE), galaxies were classified into Star-Forming Galaxies (SFGs) and Active Galactic Nuclei (AGNs) based on the Baldwin-Phillips-Terlevich (BPT) diagram. In the redshift (z) range 0.8 <= z <= 2.6, z dependence of their number densities was examined, and it was found that SFGs dominate at lower redshifts, whereas AGNs are distributed at higher redshifts. Infrared analyses using the James Webb Space Telescope (JWST) NIRSpec and MIRI for galaxies up to z ~ 6.6 show similar trends, and the number densities of SFGs and AGNs were found to cross at z ~ 1-3. Combined with the fact that the luminosity of galaxies decreases monotonically with the age of the universe, these phenomena can be interpreted by an evolutionary scenario in which SFGs merged to form QUASARs in the early universe, whose activity weakened and they changed into SFGs later, and SFGs merged again to form Seyferts in the nearby universe. Within this framework, the longstanding issues of "dead QUASARs" and "downsizing" can be naturally explained.

[abstract 22 / 36] (score: 3)
arXiv:2607.19603 [pdf, ps, other]

Title: AGN Feedback Models and AGN Demographics II: Comparing Predictions of Radiative and Total Feedback to Observations

Authors: Arjun Suresh, Michael R. Blanton,

Comments:

Subjects: astro-ph.GA

Created: 2026-07-21; Updated: 2026-07-23; Datestamp: 2026-07-23

We evaluate the radiative-mode ACTIVE GALACTIC NUCLEus (AGN) feedback models of EAGLE, SIMBA, and TNG100 by comparing their predictions for the AGN-host galaxy relationship to new observational constraints. Owing to incomplete knowledge of the underlying physics, these models differ substantially, and it remains unclear whether any of them accurately reflect reality. In a previous study, based on the demographics of narrow line AGN, we constrained $F_{\mathrm{AGN}}$, the intrinsic fraction of galaxies hosting a radiative AGN with Eddington ratio $λ> 10^{-3}$, as a function of host stellar mass ($M_*$) and specific STAR FORMATION rate (sSFR). Observationally, $F_{\mathrm{AGN}}$ declines strongly with $M_*$ for quiescent galaxies, while remaining approximately constant for star-forming systems. In this study, we find that none of the simulations reproduce these trends even qualitatively, indicating a mismatch between the simulated and observed radiative AGN populations. Additionally, since EAGLE does not explicitly distinguish between radio and radiative modes, we compare its predictions for $F_{\mathrm{AGN}}(M_*, \mathrm{sSFR})$ to our novel measurements of the combined radiative and radio mode AGN fractions. For EAGLE's constant coupling efficiency $ε_{\mathrm{f}} = 0.15$, and for the adopted standard bolometric and JET-power conversion factors in the observations, the total AGN feedback energy in EAGLE is broadly consistent with observations, though with Eddington ratios a factor of 10 greater than is observed. More detailed comparisons of EAGLE's assumptions with observations are therefore required before drawing firm conclusions.

[abstract 23 / 36] (score: 3)
arXiv:2607.19978 [pdf, ps, other]

Title: Oscillatory RECONNECTion and resonant response to wave excitation in 2D coronal null points

Authors: Konstantinos Karampelas, Tom Van Doorsselaere,

Comments: 15 pages, 14 figures

Subjects: astro-ph.SR

Created: 2026-07-22; Updated: 2026-07-23; Datestamp: 2026-07-23

Null points are MAGNETic field singularities, where the MAGNETic field strength rapidly drops to zero. In the solar atmosphere, null points are known sites of MAGNETic RECONNECTion and wave generation and are associated with highly energetic phenomena, such as flares. The aim of this study is to explore the connection between the properties of oscillatory RECONNECTion at null points and the latter's nature as resonant cavities for waves. We perform a set of 2D and 2.5D MAGNETohydrodynamics simulations of single null points in a stratified solar atmosphere, using the PLUTO code. We perturb each null point through a single propagating pulse and its reflections from the bottom boundary, hitting the null point in an asymmetrical fashion. This leads to both periodic RECONNECTion events and wave refraction around the null point. We find that each null point imposes frequencies on the RECONNECTion matching those of the waves generated from the individual resonant cavity. These frequencies also differ from those excited by the low frequency driver of the reflected waves returning to the null point, the latter lying outside the $95\%$ confidence interval. As such, excited periodic RECONNECTion can be characterised as oscillatory RECONNECTion, i.e. with properties intrinsic to the null points. Finally, the generated waves at the null propagate across the domain, reminiscent of the observed quasi-periodic fast-propagating waves. We provide results showing a direct connection between oscillatory RECONNECTion and the generated high-frequency wavetrains at null points in the solar corona. The propagating waves generated at the resonant cavity, reminiscent of the observed quasi-periodic fast-propagating waves can provide us a diagnostic tool for the RECONNECTion process at the null point and the coronal plasma conditions.

[abstract 24 / 36] (score: 3)
arXiv:2607.20080 [pdf, ps, other]

Title: Galactic Science with the LiteBIRD satellite: Spectral characterization of diffuse Galactic polarized emission at the angular power spectrum level

Authors: S. Vinzl, J. Aumont, L. Vacher, R. T. Génova-Santos, D. Adak, A. Rizzieri, H. Akamatsu, E. Allys, A. Anand, C. Baccigalupi, M. Ballardini, A. J. Banday, R. B. Barreiro, N. Bartolo, S. Basak, A. Basyrov, M. Bersanelli, N. Brancadori, T. Brinckmann, E. Calabrese, P. Campeti, A. Carones, F. Carralot, F. J. Casas, J. Chandran, M. Citran, F. Columbro, A. Coppolecchia, P. de Bernardis, E. de la Hoz, M. De Lucia, S. Della Torre, C. Dickinson, P. Diego-Palazuelos, K. Ebisawa, H. K. Eriksen, J. Errard, F. Finelli, C. Franceschet, U. Fuskeland, G. Galloni, M. Galloway, M. Gerbino, M. Gervasi, T. Ghigna, S. Giardiello, E. Gjerløw, M. Gomes, S. E. Harper, L. T. Hergt, E. Hivon, H. Ishino, K. Kikuno, K. Kohri, N. Krachmalnicoff, L. Lamagna, M. Lattanzi, C. Leloup, F. Levrier, A. I. Lonappan, M. López-Caniego, G. Luzzi, D. Maino, V. Maranchery, S. Masi, S. Matarrese, T. Matsumura, S. Micheli, M. Migliaccio, M. Monelli, L. Montier, G. Morgante, L. Mousset, R. Nagata, T. Namikawa, P. Natoli, A. Occhiuzzi, L. Pagano, A. Paiella, D. Paoletti, G. Pascual-Cisneros, G. Patanchon, V. Pavlidou, V. Pelgrims, F. Piacentini, G. Piccirilli, M. Pinchera, G. Polenta, L. Porcelli, M. Remazeilles, J. A. Rubiño-Martín, M. Ruiz-Granda, Y. Sakurai, L. Salvati, J. Sanghavi, V. Sauvage, Y. Sekimoto, M. Shiraishi, S. Stellati, R. M. Sullivan, R. Takahashi, A. Tartari, K. Tassis, K. Tateoka, L. Terenzi, M. Tomasi, M. Tristram, B. van Tent, P. Vielva, G. Weymann-Despres, E. J. Wollack,

Comments: 38 pages, 19 figures. Prepared for submission to JCAP

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

Created: 2026-07-22; Updated: 2026-07-23; Datestamp: 2026-07-23

Detection of primordial $B$-mode POLARIZATION in the cosmic microwave background (CMB) from tensor perturbations generated during inflation is a major scientific goal of future CMB missions. Its success will strongly depend on the characterization of polarized foregrounds, a challenge that the LiteBIRD satellite aims to tackle with its 15 frequency bands ranging from 40 to 402 GHz. In this work, we forecast the ability of LiteBIRD to characterize polarized dust and SYNCHROTRON emission in the diffuse interstellar medium (ISM), at the angular power spectrum level. From simulated LiteBIRD intensity and POLARIZATION maps with different foreground complexities, we compute cross-frequency angular power spectra and fit them to dust and SYNCHROTRON spectral energy distributions, which are modeled by a modified black body and a power law, respectively. We find that LiteBIRD will be able to measure the dust temperature, dust and SYNCHROTRON spectral indices and spatial correlation with dispersions as low as $σ(T_{\rm d})\sim0.2$ K, $σ(β_{\rm d})\sim0.006$, $σ(β_{\rm s})\sim0.04$ and $σ(ρ)\sim10^{-2}$, as well as to detect and quantify deviations from the proposed parametric model due to variations of the emission properties in the three dimensions of our Galaxy. Additionally, LiteBIRD is likely to rule out the power-law model of polarized foreground angular power spectra suggested by Planck data. It will also be able to detect differences in the values of $β_{\rm d}$, $T_{\rm d}$, and $β_{\rm s}$ between $E$ modes, $B$ modes, and intensity in the diffuse ISM for the first time, highlighting the joint variations of the physical conditions and the MAGNETic field structure across the Galaxy. We conclude that in addition to detailed studies of CMB POLARIZATION, LiteBIRD will open a new window onto the physical conditions governing the ISM of the Milky Way.

[abstract 25 / 36] (score: 2)
arXiv:2509.08657 [pdf, ps, other]

Title: First Overtone Mode in the Ringdown Signal of GW231028

Authors: Hai-Tian Wang,

Comments: 22 pages, 15 figures; published in Phys.Rev.Research

Subjects: gr-qc astro-ph.HE

Created: 2026-07-22; Updated: 2026-07-23; Datestamp: 2026-07-23

The properties of a remnant BLACK HOLE can be probed by analyzing the gravitational waves emitted during its ringdown phase. This signal provides a direct test of general relativity in the strong-field regime. In this study, we apply both a time-domain F-statistic framework and full Bayesian time-domain sampling to the ringdown of GW231028\_153006. We report decisive evidence for multimode content, specifically identifying both the first overtone ($\ell|m|n=221$) and the higher order ($\ell|m|n=210$). The detection of the $221$ mode is statistically significant, achieving a Bayes factor of $\sim 189.2$ and an amplitude exclusion from zero at $>7σ$ credibility for an analysis beginning at $10\,M$ postpeak. These findings are rigorously validated against the numerical relativity injection SXS:BBH:1282, which confirms that such multimode features are physically expected for a remnant with the inferred high spin and mass ratio. The inclusion of the overtone mode allows for precise constraints on the remnant's properties, yielding a redshifted final mass of $246.2^{+22.3}_{-22.4}\,{\rm M}_{\odot}$ and a final spin of $0.81_{-0.10}^{+0.07}$ (at $90\%$ credibility), consistent with full inspiral-merger-ringdown predictions. A test of the no-hair theorem, enabled by this robust multimode detection, shows consistency with general relativity.

[abstract 26 / 36] (score: 2)
arXiv:2510.00116 [pdf, ps, other]

Title: Chase Orbits, not Time: A Scalable Paradigm for Long-Duration Eccentric Gravitational-Wave Surrogates

Authors: Akash Maurya, Prayush Kumar, Scott E. Field, Chandra Kant Mishra, Peter James Nee, Kaushik Paul, Harald P. Pfeiffer, Adhrit Ravichandran, Vijay Varma,

Comments: 12 pages, 6 figures, 1 table; v3: matches version published in Phys. Rev. Lett.; model publicly available at https://github.com/gwnrtools/esigmapy

Subjects: gr-qc astro-ph.HE physics.comp-ph

Created: 2026-07-21; Updated: 2026-07-23; Datestamp: 2026-07-23

Orbital eccentricity is a key tracer of the astrophysical origins of compact binaries. Yet it remains absent from routine LIGO-Virgo-KAGRA analyses, in part because of the prohibitive computational cost of generating eccentric template waveforms. The complicated morphology of these waveforms due to the eccentric orbital timescale variations makes it difficult to construct their accurate and efficient surrogate models, especially for waveforms long enough to comprehensively cover the sensitivity bands of current ground-based gravitational-wave detectors. We present a novel and scalable surrogate building technique which makes surrogate modeling of long-duration eccentric binary BLACK HOLE waveforms both feasible and highly efficient. The technique aims to simplify the harmonic content of intermediate eccentric waveform data-pieces by modeling them in terms of an angular orbital element called the mean anomaly, instead of time. We show that this parameterization yields much more compressed surrogates than the standard time-based parameterizations. We also significantly simplify variations in waveform data-pieces across the parameter space by expressing them in terms of the instantaneous orbital eccentricity and mean anomaly to ease their parametric fitting. Building on these developments, we construct InspiralESIGMASur: a $2.77 \times 10^6M$ (850-1250 orbits) long non-spinning surrogate for the inspiral-only eccentric waveform model InspiralESIGMA [K. Paul et al., Phys. Rev. D 111, 084074 (2025)]. The methods presented in this work make it feasible to build long-duration eccentric surrogates for current as well as future third-generation gravitational-wave detectors.

[abstract 27 / 36] (score: 2)
arXiv:2601.19254 [pdf, ps, other]

Title: Constraining FRB Microstructure with Polarised Shot Noise

Authors: J. C. F. Balzan, A. Bera, C. W. James, B. Meyers,

Comments: 16 pages, 7 figures, 1 table. Published in PASA

Subjects: astro-ph.HE

Created: 2026-07-22; Updated: 2026-07-23; Datestamp: 2026-07-23

We present FIRES, a polarised shot-noise (PSN) framework that models fast radio burst (FRB) dynamic spectra as the incoherent superposition of Gaussian microshots with varying polarisation angles (PAs). Applied to the CRAFT bursts FRB 20191001A and FRB 20240318A, FIRES can reproduce key spectro-polarimetric behaviours seen in these data: scattering suppresses PA variability on the trailing edge, while the leading edge preferentially retains intrinsic structure when sufficient signal-to-noise is present. We quantify this behaviour using the PA variance ratio $\mathcal{R}_ψ$ and explore the joint plane of measured linear polarisation fraction $Π_L$ versus PA variance to identify allowed regions of microshot number $N$, intrinsic PA dispersion $σ_ψ$, and intrinsic linear fraction $Π_{L,0}$ at fixed signal-to-noise. This restricts these combinations permitted within the adopted shot-noise framework. For FRB 20191001A, the data are consistent with an extended parameter space, reflecting degeneracies between intrinsic PA structure, microshot superposition, scattering, finite sampling, noise, and the assumed microshot-property distributions. FRB 20240318A occupies a more restricted region, favouring fewer microshots and larger intrinsic PA dispersion. By combining an emission-mechanism-independent forward-modeling framework with minimal assumptions and observational constraints, FIRES facilitates qualitative and quantitative exploration of how microshot superposition, scattering, finite sampling, and noise can shape observed FRB polarimetry under the PSN model.

[abstract 28 / 36] (score: 2)
arXiv:2607.15588 [pdf, ps, other]

Title: High-Density Sound Speed and Post-Merger Dynamics

Authors: John Stroud, David Radice, Sanjay Reddy,

Comments: 31 pages, 11 figures. Fixed an outdated figure caption in figure 11, Fixed typos in the text and references

Subjects: astro-ph.HE

Created: 2026-07-21; Updated: 2026-07-23; Datestamp: 2026-07-23

The density dependence of the speed of sound in cold neutron star matter remains poorly constrained and is central to determining the high-density equation of state (EOS). While binary neutron star (BNS) merger simulations increasingly incorporate detailed microphysics, the direct impact of the sound-speed in the neutron star core on observable signatures has not been systematically explored. We address this by introducing a simplified parametrization that suppresses microphysics while allowing controlled variation of the sound speed at supranuclear densities through its derivative with respect to the baryon chemical potential. Using the WhiskyTHC code, we perform a suite of fully RELATIVISTIC BNS merger simulations and identify correlations between the sound-speed slope parameter and key merger outcomes, including remnant properties and post-merger GW frequencies. These results demonstrate that multimessenger observables are sensitive to the behavior of matter at the highest densities reached in neutron star cores. We further analyze gravitational-wave signals from the CoRe database of binary neutron star merger simulations employing more realistic equations of state. Our analysis reveals approximately EOS-independent relations between the derivative of the sound speed and the peak post-merger gravitational-wave frequency. Although these relations cannot be considered truly quasi-universal, they nonetheless indicate that post-merger gravitational waves retain measurable information about the EOS at he highest densities. At the same time, the remaining EOS dependence highlights the difficulty of isolating the underlying high-density physics and motivates the development of targeted parameterized frameworks for interpreting future multimessenger observations.

[abstract 29 / 36] (score: 2)
arXiv:2607.19619 [pdf, ps, other]

Title: Probing the matter-dominated expansion with multi-redshift Lyman-$α$ BAO from DESI DR2

Authors: Hiram K. Herrera-Alcantar, Julien Guy, Alma X. Gonzalez-Morales, Eric Armengaud, Edwin L. Pérez-Ochoa, Cristhian Garcia-Quintero, J. Aguilar, S. Ahlen, F. Beutler, D. Bianchi, A. Brodzeller, D. Brooks, E. Chaussidon, T. Claybaugh, A. Cuceu, K. S. Dawson, A. de la Macorra, Arjun Dey, S. Ferraro, A. Font-Ribera, J. E. Forero-Romero, E. Gaztañaga, G. Gutierrez, C. Hahn, K. Honscheid, D. Huterer, M. Ishak, T. Karim, R. Kehoe, D. Kirkby, A. Kremin, O. Lahav, A. Lambert, M. Landriau, L. Le Guillou, M. Manera, P. Martini, A. Meisner, R. Miquel, J. Moustakas, A. Muñoz-Gutiérrez, S. Nadathur, G. Niz, E. Paillas, N. Palanque-Delabrouille, W. J. Percival, C. Poppett, F. Prada, I. Pérez-Ràfols, C. Ravoux, G. Rossi, R. Ruggeri, L. Samushia, E. Sanchez, C. Saulder, D. Schlegel, M. Schubnell, H. Seo, J. Silber, G. Tarlé, B. A. Weaver, C. Yèche, R. Zhou,

Comments: 35 pages, 15 figures

Subjects: astro-ph.CO

Created: 2026-07-21; Updated: 2026-07-23; Datestamp: 2026-07-23

We present a multi-redshift Baryon Acoustic Oscillations (BAO) analysis of the DESI Data Release 2 (DR2) Lyman-$α$ (Ly$α$) forest, splitting the forest auto-correlation and its cross-correlation with QUASARs into three redshift bins. We obtain BAO measurements at effective redshifts $z_{\rm eff} = 2.13$, $2.40$, and $2.81$ with $\sim2.0$--$2.5\%$ precision per bin in the radial and transverse directions, corresponding to $\sim1.1$--$1.2\%$ precision for the isotropic BAO measurement. Using the same data products and modeling framework as the DESI DR2 Ly$α$ BAO analysis, we validate the pipeline on $400$ synthetic datasets and find unbiased BAO recovery with well-calibrated uncertainties. The measurements show an increase in the isotropic dilation parameter $D_V/r_d$ from $30.26\pm0.39$ to $32.22\pm0.47$ and in the Alcock-Paczyński parameter $D_M/D_H$ from $3.96\pm0.15$ to to $5.63^{+0.22}_{-0.24}$. The Hubble distance $D_H/r_d$ decreases from $9.40\pm0.20$ to $7.22\pm0.17$, providing a direct measurement of the expansion history consistent with $Λ$CDM and the expected matter-dominated scaling, with $H(z)\propto(1+z)^n$ giving $n=1.34\pm0.16$. The redshift split also provides a self-consistent measurement of clustering evolution: the Ly$α$ forest bias evolves as $(1+z)^γ$ with $γ_α=3.05\pm0.16$, the RSD parameter has a redshift evolution described by $γ_β=-0.97\pm0.26$, and the QUASAR bias evolves with $γ_Q=1.56\pm0.23$, consistent with independent QUASAR clustering measurements. Combining these three-bin BAO measurements with DESI DR2 galaxy and QUASAR BAO measurements yields cosmological constraints consistent with the single-bin Ly$α$ BAO analysis in flat $Λ$CDM and $w_0w_a$CDM and improves curvature constraints by $\sim12\%$ in $Λ$CDM$+Ω_K$.

[abstract 30 / 36] (score: 2)
arXiv:2607.19805 [pdf, ps, other]

Title: Circular-orbit dynamics and QPO constraints in static Einstein--scalar--Gauss--Bonnet BLACK HOLEs

Authors: Sardor Murodov, Bekzod Rahmatov, Otabek Umarov, Anvar Kurbaniyazov, Faisal Javed, Javlon Rayimbaev,

Comments:

Subjects: gr-qc

Created: 2026-07-22; Updated: 2026-07-23; Datestamp: 2026-07-23

Einstein--scalar--Gauss--Bonnet (EsGB) gravity provides a physically motivated framework for testing strong-field deviations from the Schwarzschild geometry through scalar hair. We study neutral-particle circular motion and high-frequency quasi-periodic oscillations (HF-QPOs) in static EsGB BLACK HOLEs described by a continued-fraction metric with a single dimensionless deformation parameter \(p\) on the Schwarzschild-connected quadratic-coupling branch. We determine the effective potential, circular-orbit energy and angular momentum, characteristic radii, and orbital and radial epicyclic frequencies, and apply the RELATIVISTIC precession model to twin-peak QPO data from XTE J1550--564, GRO J1655--40, GRS 1915+105, and M82 X-1. A source-by-source Markov chain Monte Carlo analysis shows that the observed frequency pairs can be reproduced within their uncertainties and that the radial epicyclic frequency carries the main model-level sensitivity to \(p\). However, a controlled prior-sensitivity analysis using uniform and truncated Gaussian priors finds that the marginal posterior of \(p\) closely follows the adopted prior for all four sources. This reflects the intrinsic underconstraint of fitting three correlated parameters \((M,p,r)\) to two measured frequencies. The inferred intervals therefore represent model-dependent compatibility regions rather than an independent measurement or preferred value of the EsGB deformation. The static results provide a baseline for future rotating and multi-observable tests.

[abstract 31 / 36] (score: 2)
arXiv:2607.19860 [pdf, ps, other]

Title: Quasinormal modes of the Kazakov--Solodukhin quantum-corrected BLACK HOLE: a spectral analysis

Authors: Davide Batic, Denys Dutykh, Mark Sukaiti,

Comments: 60 pages, 10 figures

Subjects: gr-qc

Created: 2026-07-22; Updated: 2026-07-23; Datestamp: 2026-07-23

We compute quasinormal modes of the Kazakov--Solodukhin quantum-corrected BLACK HOLE using a high-precision Chebyshev spectral method. After factoring out the quasinormal mode asymptotics at the event horizon and at spatial infinity, the radial problem is reduced to a quadratic matrix pencil for the dimensionless frequency $Ω=Mω$. We apply this framework to minimally coupled scalar perturbations, electroMAGNETic perturbations, a non-minimally coupled scalar field, and an axial effective source Regge--Wheeler-type gravitational sector. The latter is treated as an effective axial model, rather than as the full gravitational perturbation problem, because the Kazakov--Solodukhin spacetime is not Ricci flat. Our results reproduce the available WKB, time-domain, Mashhoon, and asymptotic-iteration benchmarks in their common regimes of validity, after accounting for the different normalisations used in the literature. The spectral method also resolves additional overtones and candidate purely imaginary overdamped roots. In several sectors, these roots exhibit a spacing scale close to $Mκ=1/4$, with occasional multiple gaps in the retained numerical sequence. In the near-extremal, but still subextremal, regime, the detected purely imaginary branches approach an approximately equally spaced surface-gravity-scaled ladder, while the oscillatory spectra remain sector dependent. Within the parameter ranges and resolutions considered here, all retained modes have $\ImΩ<0$, and no stable growing mode is detected.

[abstract 32 / 36] (score: 2)
arXiv:2607.19930 [pdf, ps, other]

Title: Reduced-order non-self-consistent Monte Carlo simulation of a planar MAGNETron discharge: electron heating, recapture and racetrack formation

Authors: Franz F. Locker, Georg Strauß,

Comments:

Subjects: physics.plasm-ph physics.comp-ph

Created: 2026-07-22; Updated: 2026-07-23; Datestamp: 2026-07-23

A reduced-order non-self-consistent Monte Carlo model is presented for a circular planar MAGNETron discharge in argon. The model combines two MAGNETic-field representations, namely a superposition of MAGNETic dipoles and a numerically integrated field of the finite permanent MAGNETs, with a prescribed one-dimensional sheath-bulk potential, adaptive fourth-order Runge-Kutta orbit integration, and a null-collision treatment of electron-argon collisions. The collision module reproduces the dependence of the electron drift velocity on the reduced electric field, but overestimates its absolute value by approximately a factor of 1.5. The resulting transport predictions are therefore interpreted semi-quantitatively. Applied to a MAGNETron geometry based on published Langmuir-probe measurements, the simulations reproduce the qualitative emergence of a cold electron population away from the cathode while retaining a hotter near-cathode component. Electrons returning to the cathode are reflected with a prescribed probability RC, which controls their availability for further ionising collisions. For racetrack calculations initiated with at least 2 x 10^4 cathode-emitted electrons and RC = 0.5, the finite-MAGNET field produces a more sharply localised erosion profile whose full width at half maximum is close to a geometric racetrack-width estimate. The dipole approximation yields a broader profile. The model is not a replacement for self-consistent PIC-MCC simulations, but is a computationally light tool for comparing MAGNETic-field representations and analysing electron heating, ionisation localisation, and racetrack formation.

[abstract 33 / 36] (score: 2)
arXiv:2607.20038 [pdf, ps, other]

Title: A comprehensive study of comet 67P/Churyumov-Gerasimenko in the 2021/2022 apparition. II. Colorimetry, polarimetry, modeling

Authors: Vera Rosenbush, Oleksandra Ivanova, Johannes Markkanen, Igor Lukyanyk, Valerii Kleshchonok, Ludmilla Kolokolova, Colin Snodgrass, Elena Shablovinskaya,

Comments: 15 pages, 11 figures

Subjects: astro-ph.EP

Created: 2026-07-22; Updated: 2026-07-23; Datestamp: 2026-07-23

This paper presents the second part of our multi-technique observational study of comet 67P during its 2021-2022 apparition. While the first paper focused on photometry and spectroscopy, here we investigate the dust color and linear POLARIZATION of the coma. Imaging in the g-sdss and r-sdss filters was obtained with the 6-m BTA SAO Telescope, and aperture polarimetry was performed with the 2.6-m Shajn Telescope (CrAO) and the 2-m RCC Telescope. Observations at phase angles of 47.9 deg (6 October 2021) and 10.5 deg (6 February 2022) show negative POLARIZATION of about 0.5-2.5% at 10.5 deg and positive POLARIZATION of about 11% at 47.9 deg. The dust color was red, reaching about 0.8 mag near the nucleus and in the tail, and decreasing to about 0.2 mag in the coma and JET within 20,000 km of the nucleus. Spatial maps reveal a gradual decrease in color index and a corresponding increase in POLARIZATION with distance from the nucleus. Numerical modeling using ballistic particle-cluster aggregates composed of equal fractions of silicates and organics indicates that the coma is dominated by particles larger than 10 micrometers, while local POLARIZATION enhancements are consistent with regions containing smaller (1-10 micrometer) grains. Combining our aperture measurements with published data from four previous apparitions confirms that comet 67P belongs to the high-POLARIZATION class. The unusually high positive POLARIZATION observed during the 2021/22 apparition, together with the relatively isotropic coma morphology, suggests that the dust properties may have changed after the 2015/16 apparition.

[abstract 34 / 36] (score: 2)
arXiv:2607.20281 [pdf, ps, other]

Title: Parametric Decay of Broadband Lower Hybrid Waves

Authors: S. Jin, A. K. Ram, S. G. Baek, P. T. Bonoli,

Comments:

Subjects: physics.plasm-ph

Created: 2026-07-22; Updated: 2026-07-23; Datestamp: 2026-07-23

We derive a nonlinear dispersion relation for the parametric decay of an arbitrary lower hybrid pump spectrum, generalizing the standard three-wave treatment to the broadband case. Finite pump bandwidth is found to reorganize the decay spectrum, collapsing the nonresonant continuum predicted by monochromatic theory into narrow bands localized at ion cyclotron harmonics. This reorganization is distinct from the gradual suppression usually associated with finite pump coherence: it occurs at modest bandwidth, while growth rates remain large. Accounting for finite bandwidth restores agreement between theoretical growth rate spectra and sideband measurements from lower hybrid current drive experiments on Alcator C-Mod. More broadly, these results suggest that pump coherence can qualitatively determine the accessible decay channels in MAGNETized plasmas with kinetic resonances.

[abstract 35 / 36] (score: 2)
arXiv:2607.20314 [pdf, ps, other]

Title: Long-lived intermittent accretion disks in the jittering JETs explosion mechanism (JJEM) of core-collapse SUPERNOVAe

Authors: Noam Soker,

Comments: It will be submitted in two days to allow for comments (including missing references)

Subjects: astro-ph.HE

Created: 2026-07-22; Updated: 2026-07-23; Datestamp: 2026-07-23

Motivated by observations of core-collapse SUPERNOVA (CCSN) remnants that suggest cases where one to three energetic pairs of JETs dominate the CCSN remnant morphology and, hence, the CCSN explosion energy, I examine the formation of long-lived intermittent accretion disks that launch such pairs of energetic JETs in the framework of the jittering-JETs explosion mechanism (JJEM). In the JJEM, pairs of JETs explode all CCSNe. In most CCSNe, stochastic angular momentum fluctuations in the convective zones of the pre-collapse core seed instabilities above the newly born neutron star that lead to the formation of intermittent accretion disks. These disks launch several to about twenty pairs of JETs that explode the star. CCSNRs with signatures of 1-3 very energetic pairs of JETs require long-lived, intermittent accretion disks. I show that viscosity-driven angular momentum transport in the disk can prolong its lifetime even when material with zero angular momentum continues to feed the disk. In addition, the JETs prevent matter from accreting from the polar direction, thereby extending the disk's lifetime. These two positive feedback processes, and the fluctuations that, in some cases, add up to a positive angular momentum, can substantially prolong the lifetime of 1-3 intermittent accretion disks (or none), which then launch the energetic pairs of JETs. This study adds to the wide variety of morphologies that the JJEM can explain, hence strengthening the JJEM as the primary explosion mechanism of CCSNE.

[abstract 36 / 36] (score: 2)
arXiv:2607.20371 [pdf, ps, other]

Title: The burgeoning rise of the 21-cm forest I: constraints on the optical depth of the intergalactic medium at $5.38 < z < 5.84$

Authors: Chanasorn Kongprachaya, Gianni Bernardi, Emilio Ceccotti, Andrei Mesinger, Benedetta Ciardi, Oleg M. Smirnov,

Comments: 15 pages, 24 figures, 11 tables. Submitted to Astronomy & Astrophysics (A&A)

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

Created: 2026-07-22; Updated: 2026-07-23; Datestamp: 2026-07-23

The redshifted 21-cm line is a promising probe of the Epoch of Reionization, during which the first generation of stars ionized the InterGalactic Medium (IGM). We aimed to constrain the IGM neutral Hydrogen fraction and spin temperature via redshifted 21-cm absorption against high-redshift radio sources. We analysed an 18-hour observation of the radio-loud QUASAR PSO J352.4034-15.3373 ($z = 5.84$) in the 203-222.5 MHz band. We obtained a continuum image with a $0.66$ mJy/beam rms noise and a spectrum with $3.6$ mJy/beam rms noise per 390 kHz-wide channel. We fit the QUASAR spectrum with a power-law continuum modified by an intervening 21-cm absorption, testing two scenarios: an island model, a residual cold neutral Hydrogen patch surviving at the end of reionization, and a global model, approximating the overall decline of the IGM HI fraction and spin temperature with redshift. Combining archival data spanning 150 MHz to 3.0 GHz with our measurements, we determined a QUASAR flux density of $86.8 \pm 1.1$ mJy at 200 MHz and a spectral index of $-0.88 \pm 0.02$ across the full frequency range. We found no evidence for the 21-cm absorption from intervening neutral Hydrogen at $5.38