Current date: 2026-02-17
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Datestamp limit: 2026-02-17 (0 days ago)
Created/updated limit: 2026-02-10 (7 days ago)
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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=2026-02-17&until=2026-02-17&set=physics&metadataPrefix=arXiv
Scoring abstracts
Number of records retrieved: 1021
Keyword score statistics
score 11 -- 1 abstracts
score 8 -- 2 abstracts
score 7 -- 1 abstracts
score 6 -- 1 abstracts
score 5 -- 6 abstracts
score 4 -- 8 abstracts
score 3 -- 16 abstracts
score 2 -- 22 abstracts
in total -- 57 abstracts
Articles that appeared on 2026-02-17
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[abstract 1 / 57] Wow! (score: 11)
- Title: LHAASO observation of Mrk 421 during 2021 March - 2024 March: a comprehensive VHE catalog of multi-timescale outbursts and its time average behaviorAuthors: The LHAASO Collaboration, Zhen Cao, F. Aharonian, Y. X. Bai, Y. W. Bao, D. Bastieri, X. J. Bi, Y. J. Bi, W. Bian, J. Blunier, A. V. Bukevich, C. M. Cai, Y. Y. Cai, W. Y. Cao, Zhe Cao, J. Chang, J. F. Chang, E. S. Chen, G. H. Chen, H. K. Chen, L. F. Chen, Liang Chen, Long Chen, M. J. Chen, M. L. Chen, Q. H. Chen, S. Chen, S. H. Chen, S. Z. Chen, T. L. Chen, X. B. Chen, X. J. Chen, X. P. Chen, Y. Chen, N. Cheng, Q. Y. Cheng, Y. D. Cheng, M. Y. Cui, S. W. Cui, X. H. Cui, Y. D. Cui, B. Z. Dai, H. L. Dai, Z. G. Dai, Danzengluobu, Y. X. Diao, A. J. Dong, X. Q. Dong, K. K. Duan, J. H. Fan, Y. Z. Fan, J. Fang, J. H. Fang, K. Fang, C. F. Feng, H. Feng, L. Feng, S. H. Feng, X. T. Feng, Y. Feng, Y. L. Feng, S. Gabici, B. Gao, Q. Gao, W. Gao, W. K. Gao, M. M. Ge, T. T. Ge, L. S. Geng, G. Giacinti, G. H. Gong, Q. B. Gou, M. H. Gu, F. L. Guo, J. Guo, K. J. Guo, X. L. Guo, Y. Q. Guo, Y. Y. Guo, R. P. Han, O. A. Hannuksela, M. Hasan, H. H. He, H. N. He, J. Y. He, X. Y. He, Y. He, S. Hernández-Cadena, B. W. Hou, C. Hou, X. Hou, H. B. Hu, S. C. Hu, C. Huang, D. H. Huang, J. J. Huang, X. L. Huang, X. T. Huang, X. Y. Huang, Y. Huang, Y. Y. Huang, A. Inventar, X. L. Ji, H. Y. Jia, K. Jia, H. B. Jiang, K. Jiang, X. W. Jiang, Z. J. Jiang, M. Jin, S. Kaci, M. M. Kang, I. Karpikov, D. Khangulyan, D. Kuleshov, K. Kurinov, Cheng Li, Cong Li, D. Li, F. Li, H. B. Li, H. C. Li, Jian Li, Jie Li, K. Li, L. Li, R. L. Li, S. D. Li, T. Y. Li, W. L. Li, X. R. Li, Y. Li, Zhe Li, Zhuo Li, E. W. Liang, Y. F. Liang, S. J. Lin, B. Liu, C. Liu, D. Liu, D. B. Liu, H. Liu, J. Liu, J. L. Liu, J. R. Liu, M. Y. Liu, R. Y. Liu, S. M. Liu, W. Liu, X. Liu, Y. Liu, Y. Liu, Y. N. Liu, Y. Q. Lou, Q. Luo, Y. Luo, H. K. Lv, B. Q. Ma, L. L. Ma, X. H. Ma, I. O. Maliy, J. R. Mao, Z. Min, W. Mitthumsiri, Y. Mizuno, G. B. Mou, A. Neronov, K. C. Y. Ng, M. Y. Ni, L. Nie, L. J. Ou, Z. W. Ou, P. Pattarakijwanich, Z. Y. Pei, D. Y. Peng, J. C. Qi, M. Y. Qi, J. J. Qin, D. Qu, A. Raza, C. Y. Ren, D. Ruffolo, A. Sáiz, D. Savchenko, D. Semikoz, L. Shao, O. Shchegolev, Y. Z. Shen, X. D. Sheng, Z. D. Shi, F. W. Shu, H. C. Song, Yu. V. Stenkin, Y. Su, D. X. Sun, H. Sun, J. X. Sun, Q. N. Sun, X. N. Sun, Z. B. Sun, N. H. Tabasam, J. Takata, P. H. T. Tam, H. B. Tan, Q. W. Tang, R. Tang, Z. B. Tang, W. W. Tian, C. N. Tong, L. H. Wan, C. Wang, D. H. Wang, G. W. Wang, H. G. Wang, J. C. Wang, K. Wang, Kai Wang, Kai Wang, L. P. Wang, L. Y. Wang, L. Y. Wang, R. Wang, W. Wang, X. G. Wang, X. J. Wang, X. Y. Wang, Y. Wang, Y. D. Wang, Z. H. Wang, Z. X. Wang, Zheng Wang, D. M. Wei, J. J. Wei, Y. J. Wei, T. Wen, S. S. Weng, C. Y. Wu, H. R. Wu, Q. W. Wu, S. Wu, X. F. Wu, Y. S. Wu, S. Q. Xi, J. Xia, J. J. Xia, G. M. Xiang, D. X. Xiao, G. Xiao, Y. F. Xiao, Y. L. Xin, H. D. Xing, Y. Xing, D. R. Xiong, B. N. Xu, C. Y. Xu, D. L. Xu, R. F. Xu, R. X. Xu, S. S. Xu, W. L. Xu, L. Xue, D. H. Yan, T. Yan, C. W. Yang, C. Y. Yang, F. F. Yang, L. L. Yang, M. J. Yang, R. Z. Yang, W. X. Yang, Z. H. Yang, Z. G. Yao, X. A. Ye, L. Q. Yin, N. Yin, X. H. You, Z. Y. You, Q. Yuan, H. Yue, H. D. Zeng, T. X. Zeng, W. Zeng, X. T. Zeng, M. Zha, B. B. Zhang, B. T. Zhang, C. Zhang, H. Zhang, H. M. Zhang, H. Y. Zhang, J. L. Zhang, J. Y. Zhang, Li Zhang, P. F. Zhang, R. Zhang, S. R. Zhang, S. S. Zhang, S. Y. Zhang, W. Zhang, W. Y. Zhang, X. Zhang, X. P. Zhang, Yi Zhang, Yong Zhang, Z. P. Zhang, J. Zhao, L. Zhao, L. Z. Zhao, S. P. Zhao, X. H. Zhao, Z. H. Zhao, F. Zheng, T. C. Zheng, B. Zhou, H. Zhou, J. N. Zhou, M. Zhou, P. Zhou, R. Zhou, X. X. Zhou, X. X. Zhou, B. Y. Zhu, C. G. Zhu, F. R. Zhu, H. Zhu, K. J. Zhu, Y. C. Zou, X. Zuo,Comments: 34 pages, 20 figuresSubjects: astro-ph.HECreated: 2026-02-13; Updated: 2026-02-17; Datestamp: 2026-02-17
The Large High Altitude Air Shower Observatory (LHAASO) monitors sources within its field of view for up to 7 hours daily, achieving a duty cycle exceeding 98% and an annual point-source sensitivity of 1.5% Crab Units (CU) in the very high energy (VHE) band. This unbiased sky-survey mode facilitates systematic monitoring and investigation of outburst phenomena. In this paper, we present results from an unprecedented three-year monitoring campaign (March 2021--March 2024) of Mrk421 using LHAASO, spanning energies from 0.4 TeV to 20 TeV. We find that the BLAZAR stayed in a quiescent state in 2021 and became active starting in 2022 with a total of 23 VHE outburst events identified, where the highest observed daily significance reaches $20\,σ$ with a flux equivalent to approximately 3.3~CU. LHAASO's continuous monitoring suggests the flaring occupancy of Mrk~421 to be around 14%. During long-term monitoring, multiwavelength (MWL) variability and correlation analyses are conducted using complementary data from FERMI-LAT, MAXI-GSC, SWIFT-XRT, and ZTF. A significant correlation ($>3\,σ$) is observed between X-ray and VHE bands with no detectable time lag, while the correlation between GeV and TeV bands is weaker. The flux distribution of the TeV emission during the quiescent state is different from that in the active state, implying the existence of two modes of energy dissipation in the BLAZAR JET. Using simultaneous MWL data, we also analyzed both the long-term and outburst-period SEDs, and discussed the possible origin of the outburst events.
[abstract 2 / 57] Wow! (score: 8) - Title: Constraining Binary Neutron Star Populations using Short Gamma-Ray Burst ObservationsAuthors: Alessio Ludovico De Santis, Samuele Ronchini, Filippo Santoliquido, Marica Branchesi,Comments:Subjects: astro-ph.HE astro-ph.GACreated: 2026-02-13; Updated: 2026-02-17; Datestamp: 2026-02-17
The landmark multi-messenger observations of the binary neutron star (BNS) merger GW170817 provided firm evidence that such mergers can produce short GAMMA-RAY BURSTs (sGRBs). However, the limited number of BNS detections by current gravitational-wave (GW) observatories raises the question of whether BNS mergers alone can account for the full observed sGRB population. We analyze a comprehensive set of 64 BNS population synthesis models with a Monte Carlo-based framework to reproduce the properties of sGRBs detected by FERMI-GBM over the past 16 years. We consider three JET geometry scenarios: a universal structured JET calibrated to GW170817, a universal top-hat JET, and a non-universal top-hat JET with distributions of core opening angles. Our results show that models characterized by low local BNS merger rates ($R_{BNS}(0) \lesssim 50$ Gpc$^{-3}$ yr$^{-1}$) predict too few observable sGRBs to reproduce the FERMI-GBM population, effectively disfavoring them as sole progenitors. Even when relaxing assumptions on JET geometry, low-rate models remain viable only for wide JETs ($θ_c \ge 15^\circ$), in tension with the narrow JET cores ($θ_c \approx 6^\circ$) inferred from sGRB afterglow observations. In contrast, models with local merger rates of order $R_{BNS}(0) \approx 100$ Gpc$^{-3}$ yr$^{-1}$ successfully reproduce the observed sGRB population, assuming a plausible fraction of BNS mergers launch RELATIVISTIC JETs and realistic JET geometries. This analysis highlights the power of combining GW observations of BNS mergers with electroMAGNETic observations of sGRBs to place robust constraints on the BNS merger population and to assess their role as progenitors of sGRBs.
[abstract 3 / 57] Wow! (score: 8) - Title: H.E.S.S. detection of the PSR J0855-4644 nebulaAuthors: F. Aharonian, H. Ashkar, M. Backes, R. Batzofin, Y. Becherini, D. Berge, K. Bernlöhr, M. Böttcher, C. Boisson, J. Bolmont, F. Brun, B. Bruno, C. Burger-Scheidlin, T. Bylund, S. Casanova, D. Cecchin Momesso, J. Celic, M. Cerruti, A. Chen, M. Chernyakova, J. O. Chibueze, O. Chibueze, B. Cornejo, G. Cotter, G. Cozzolongo, J. de Assis Scarpin, M. de Bony de Lavergne, M. de Naurois, E. de Oña Wilhelmi, A. G. Delgado Giler, J. Devin, A. Dmytriiev, K. Egberts, K. Egg, J. -P. Ernenwein, C. Escañuela Nieves, P. Fauverge, K. Feijen, M. D. Filipovic, G. Fontaine, S. Funk, S. Gabici, Y. A. Gallant, M. Genaro, J. F. Glicenstein, J. Glombitza, P. Goswami, M. -H. Grondin, L. Heckmann, B. Heß, W. Hofmann, T. L. Holch, M. Holler, D. Horns, M. Jamrozy, F. Jankowsky, A. Jardin-Blicq, I. Jaroschewski, D. Jimeno, I. Jung-Richardt, E. Kasai, K. Katarzyński, D. Kerszberg, B. Khélifi, W. Kluźniak, N. Komin, K. Kosack, D. Kostunin, R. G. Lang, S. Lazarević, A. Lemière, M. Lemoine-Goumard, J. -P. Lenain, P. Liniewicz, A. Luashvili, J. Mackey, D. Malyshev, D. Malyshev, V. Marandon, M. G. F. Mayer, A. Mehta, A. M. W. Mitchell, R. Moderski, L. Mohrmann, E. Moulin, J. Niemiec, P. O'Brien, L. Olivera-Nieto, M. O. Moghadam, S. Panny, M. Panter, R. D. Parsons, P. Pichard, T. Preis, G. Pühlhofer, M. Punch, A. Quirrenbach, A. Reimer, O. Reimer, I. Reis, Q. Remy, H. X. Ren, B. Reville, F. Rieger, G. Rowell, B. Rudak, K. Sabri, V. Sahakian, M. Sasaki, F. Schüssler, J. N. S. Shapopi, W. Si Said, Ł. Stawarz, R. Steenkamp, S. Steinmassl, T. Tanaka, A. M. Taylor, G. L. Taylor, R. Terrier, Y. Tian, M. Tsirou, T. Unbehaunz, C. van Eldik, M. Vecchi, C. Venter, J. Vink, V. Voitsekhovskyi, T. Wach, S. J. Wagner, A. Wierzcholska, M. Zacharias, A. Zech, W. Zhong, F. Acero, L. Giunti,Comments: 10 pages, 7 figures. Accepted to A&A; Corresponding authors: K. Feijen, B. Khélifi, R. Terrier, K. KosackSubjects: astro-ph.HECreated: 2026-02-16; Updated: 2026-02-17; Datestamp: 2026-02-17
HESS J0852-463 is a TeV γ-ray source located in the Galactic plane. The region consists of a SUPERNOVA remnant (SNR, RX J0852.0-4622) with a shell-like morphology, commonly referred to as Vela Junior, and a pulsar denoted PSR J0855-4644. Pulsars are among the most efficient leptonic accelerators in our Galaxy, making this region particularly interesting to study. We utilise the most recent data taken by the High Energy Stereoscopic System (H.E.S.S.), to investigate any γ-ray emission associated with the pulsar in this region, PSR J0855-4644. We applied a full forward folding method on the H.E.S.S. data. Utilising 3D modelling techniques, we evaluated the TeV γ-ray emission towards the various components of this complex system. The distinct energy-dependent morphology observed in our data motivates further investigation of this source. We resolved the emission in the Vela Junior region into various components, several of which correspond to the SNR itself. In particular, we find a new extended component which is coincident with the position of PSR J0855-4644. The spectrum follows a power-law distribution with a best-fit index of ΓE = 1.81 \pm 0.07stat which differs from the properties of the surrounding γ-ray emission of the Vela Junior SNR. A one-zone leptonic joint fit between the X-rays (from XMM-Newton) and γ-rays (from H.E.S.S.) leads to a lower limit on the MAGNETic field of 1.6μG and a spectral index of α = 1.88 \pm 0.01, in line with expectations of pulsar wind nebulae (PWNe). In this paper, we report the first detection of the PWN of PSR J0855-4644 at TeV energies with the H.E.S.S. experiment at a significance of 12.2σ. This is attributed to the advanced techniques of the 3D analysis. Based on the pulsar's characteristics, its PWN is consistent with the known TeV PWNe population in the Galaxy.
[abstract 4 / 57] Wow! (score: 7) - Title: Production of Jets before Neutron Star MergersAuthors: Praveen Sharma, Maxim Lyutikov, Slava G. Turyshev, Maxim V. Barkov,Comments:Subjects: astro-ph.HECreated: 2026-02-15; Updated: 2026-02-17; Datestamp: 2026-02-17
We demonstrate that MAGNETospheric interactions between merging neutron stars (NSs) generate dual-JETted current outflows, analogous to the Alfvén wings observed during planetary interactions in the Solar System. Using 3D RELATIVISTIC MHD simulations, we model the interaction as a conducting sphere moving through a highly MAGNETized plasma of the companion's MAGNETosphere. Unusually, the interaction operates in a regime that is RELATIVISTIC yet sub-Alfvénic. ElectroMAGNETic draping amplifies MAGNETic fields in a narrow layer near the stellar surface, leading to the generation of electric currents along the local MAGNETic field. The generation of beamed outflows enhances instantaneous power of the pulsar-like radio and high energy emission, produces spin/orbital modulations, and is likely to lead to observable precursor emission preceding the main gravitational wave event.
[abstract 5 / 57] Yes (score: 6) - Title: A universal critical accretion rate for BLACK HOLE JET formationAuthors: Adelle J. Goodwin, Andrew Mummery,Comments: 8 pages + 48 pages of appendices. 3 Figures + 19 Figures in appendices. Under review, comments welcome. Both authors contributed equallySubjects: astro-ph.HECreated: 2026-02-16; Updated: 2026-02-17; Datestamp: 2026-02-17
It has long been suspected that BLACK HOLE accretion-outflow coupling is invariant from the stellar to supermassive scales. Stellar mass BLACK HOLE accretion flows are known to launch JETs and outflows as they transition through critical accretion rate thresholds, with values well constrained observationally owing to their short evolutionary timescales. In contrast, accretion flows in typical supermassive BLACK HOLE (SMBH) systems (those in ACTIVE GALACTIC NUCLEi) evolve over thousands of years, making the critical transitions at which JETs are launched impossible to constrain in individual systems. Tidal disruption events (TDEs) provide the unique opportunity to witness the birth and evolution of an accretion flow onto a SMBH which evolves on timescales of years. Here we show that TDEs launch outflows during a super-Eddington accretion phase and a second, physically distinct outflow, at a critical accretion rate of $L_{\rm crit} \approx0.02$ $L_{\rm Edd}$, the same as the critical accretion rate for state transitions observed in accreting stellar mass BLACK HOLEs. This work naturally explains the mechanism, observed properties, and detection rate for prompt and delayed outflows observed in TDEs, which until now have been open problems. More broadly, we demonstrate that SMBHs exhibit the same accretion-outflow coupling as stellar mass BLACK HOLEs and that the critical low accretion rate threshold for JET formation in BLACK HOLEs is scale invariant.
[abstract 6 / 57] Yes (score: 5) - Title: Detecting prompt and afterglow JET emission of gravitational wave events from LIGO/Virgo/KAGRA and next generation detectorsAuthors: Ravjit Kaur, Brendan O'Connor, Antonella Palmese, Keerthi Kunnumkai,Comments: Accepted for publication in ApJ, 33 pages, 13 figures, 4 tablesSubjects: astro-ph.HECreated: 2026-02-13; Updated: 2026-02-17; Datestamp: 2026-02-17
Following the wealth of new results enabled by multimessenger observations of the binary neutron star (BNS) merger GW170817, the next goal is increasing the number of detections of electroMAGNETic (EM) counterparts to gravitational wave (GW) events. We study the detectability of the prompt emission and afterglows produced by the RELATIVISTIC JETs launched by BNS mergers that will be detected by LIGO-Virgo-KAGRA during their fifth observing run (O5), and by next generation (XG) GW detectors (Einstein Telescope and Cosmic Explorer). We quantify the impact of various BNS merger and JET afterglow parameters on the likelihood of detection, focusing on the impact of the observer's viewing angle and the JET's core half-opening angle. We explore detectability over a wide range of current state-of-the-art facilities (e.g., the James Webb Space Telescope, Chandra X-ray Observatory) as well as upcoming next-generation facilities (e.g., AXIS, NewAthena, ngVLA, SKA). We find that a few GW events (~0-4) per year may have a detectable afterglow component in O5, with the largest detection rates expected with SKA in the radio and JWST in the near-infrared. In the XG era, hundreds of multimessenger detections of afterglows per year may be possible with a range of instruments, such as NewAthena in the X-ray and ngVLA in the radio. While zero to a few GW events per year are expected to be accompanied by a detectable prompt emission in O5, dozens per year may be detectable in XG.
[abstract 7 / 57] Yes (score: 5) - Title: Gamma-Ray Millisecond Pulsars: Off-pulse Emission Characteristics, Phase-Resolved Pseudo-Luminosity--Cutoff Energy Correlation, and High-energy Pulsed EmissionAuthors: Ming-Yu Lei, Zhao-Qiang Shen, Zi-Qing Xia, Xiaoyuan Huang,Comments: 23 pages, 8 figures, 3 tables, accepted by ApJSSubjects: astro-ph.HECreated: 2026-02-15; Updated: 2026-02-17; Datestamp: 2026-02-17
We investigate the $γ$-ray emission from 38 millisecond pulsars using 15 years of FERMI-LAT Pass 8 data in the 0.3--500 GeV range. Off-pulse intervals defined objectively with the Bayesian Blocks algorithm reveal significant off-pulse emission from 15 sources. Ten exhibit clear spectral cutoffs indicative of MAGNETospheric origin, while the remaining five show no compelling evidence for non-MAGNETospheric origins, as their off-pulse emission is spatially unresolved and inconsistent with hadronic, inverse Compton, or intrabinary contributions, implying a likely MAGNETospheric origin. We perform phase-resolved spectral fits for these 15 sources. In 11 of them, the cutoff energy $E_{\rm cut}$ varies markedly with rotation phase and correlates positively with the phase-resolved photon counts. Defining a phase-resolved pseudo-luminosity, these 11 pulsars follow a linear relation between $\log_{10}L$ and $\log_{10}E_{\rm cut}$, with slope $α= 2.31^{+0.22}_{-0.25}$, consistent with curvature-radiation predictions from the equatorial current sheet ($α\approx 2.29$). The same relation appears in the bright pulsar J0614$-$3329, implying the same emission mechanism across all rotational phases. We detect pulsed emission above 10 GeV from 19 sources, and a significant fraction of these also exhibit robust off-pulse emission. The coexistence of robust off-pulse flux and pulsed emission extending to high energies challenges standard outer-gap models. While other frameworks can also produce off-pulse flux, the phase-resolved $L$--$E_{\rm cut}$ correlation could provide a key diagnostic, and our measured slope may provide new evidence supporting the equatorial current sheet scenario as an important $γ$-ray emission mechanism in millisecond pulsars.
[abstract 8 / 57] Yes (score: 5) - Title: Modeling YSO Jets in 3D II: Accretion-Fed, Star-Anchored Poynting Jets in the Low-Density Polar Cavity Powered by Disk-Magnetosphere InteractionAuthors: Yisheng Tu, Zhi-Yun Li, Zhaohuan Zhu, Xiao Hu, Chun-Yen Hsu,Comments: Accepted by ApJSubjects: astro-ph.SR astro-ph.EPCreated: 2026-02-16; Updated: 2026-02-17; Datestamp: 2026-02-17
The origin of JETs in young stellar objects (YSOs) remains a subject of active investigation. We present a 3D MAGNETohydrodynamic simulation of JET launching in YSOs, focusing on the interaction between the stellar MAGNETosphere and the accretion disk. In our model, a fast, low-density bipolar JET is powered by disk-MAGNETosphere interaction and launched through the polar cavity that is mass-loaded from the disk rather than the star. Specifically, outflows are driven by toroidal MAGNETic pressure generated along "two-legged" field lines, anchored at a MAGNETically dominated stellar footpoint and a mass-dominated point on the (MAGNETically elevated) disk surface via a cyclic "load-fire-reload" process: in the "load" stage, differential rotation between stellar and disk footpoints generates toroidal MAGNETic pressure; in the "fire" stage, vertical gradients in the toroidal field accelerate plasma and transport Poynting flux into the polar cavity; in the "reload" stage, MAGNETic RECONNECTion allows the cycle to repeat, reforming "two-legged" field lines. These field lines are not required to be fully reset to a dipolar loop configuration; it is only required that the disk-end be shallowly embedded in the (elevated) disk surface. This rapid, asynchronous process produces a continuous, large-scale outflow. The resulting MAGNETically dominated (Poynting) JET, accelerated by MAGNETic pressure within the low-density polar cavity, is distinct from the denser, slower disk wind launched through the classic MAGNETic-tower mechanism. Comparison with a disk-only model shows that the rotating stellar MAGNETosphere promotes bipolar JET launching by shaping a MAGNETic geometry favorable to symmetric outflows.
[abstract 9 / 57] Yes (score: 5) - Title: Unprecedented Multipoint Observation of Spatially Varying ICME Turbulence of Different Ages during October 2024 Extreme Solar Storm at 1 AUAuthors: Shibotosh Biswas, Ankush Bhaskar, SG Abitha, Omkar Dhamane, Sanchita Pal, Dibyendu Chakrabarty, Vipin K Yadav,Comments: Submitted to the Astrophysical Journal Supplement SeriesSubjects: astro-ph.SR physics.plasm-ph physics.space-phCreated: 2026-02-14; Updated: 2026-02-17; Datestamp: 2026-02-17
Understanding turbulence in interplanetary coronal mass ejections is fundamental to space plasma research and critical for assessing the impact of space weather on geospace. Turbulence governs energy cascade, plasma heating, MAGNETic RECONNECTion, and solar wind MAGNETosphere coupling, thereby influencing both ICME evolution and geoeffectiveness. While previous event-based and statistical studies have examined ICME turbulence and its radial evolution in great detail, no significant measurements of ICME MAGNETic turbulence at a specific vantage point have been made using multiple observatories separated azimuthally. Here, we present the first multipoint analysis of MHD turbulence across ICME plasma regions, using four spacecraft at the Sun-Earth L1 point, separated by 80 RE along the dawn-dusk direction. Previous studies reveal that ICME shocks, sheaths, and MAGNETic clouds are highly non-uniform, with strong azimuthal variability. Using high-resolution MAGNETic field observations from ISRO's Aditya-L1, NASA's Wind and ACE, and NOAA's DSCOVR, we analyze turbulence associated with the 10th October 2024 solar storm, which triggered the second-strongest geoMAGNETic storm of solar cycle 25. Our results reveal significant variability and differing turbulence maturity across small separations, supported by analysis of field-aligned and perpendicular MAGNETic field cascades, indicating strong anisotropies. Sheath turbulence is substantially modified by shock induced energy injection. Evidence of compressible turbulence and plasma energization at the flux rope interaction region indicates that internal processes, such as MAGNETic RECONNECTion, strongly influence ICME plasma evolution, highlighting pronounced spatial variability in turbulence and plasma states observed by multiple L1 monitors near Earth and underscoring their potential role in space weather impacts.
[abstract 10 / 57] Yes (score: 5) - Title: PeV neutrons as origin of separated SS433 TeV signalsAuthors: D. Fargion, P. G. De Sanctis Lucentini, S. Turriziani, M. Y. Khlopov, D. Sopin,Comments: 11 pages, 2 figures,. arXiv admin note: substantial text overlap with arXiv:2512.07012Subjects: astro-ph.HE hep-phCreated: 2026-02-15; Updated: 2026-02-17; Datestamp: 2026-02-17
The SS433, a well-known binary system with an internal BLACK HOLE, have shown since half a century, an inner (a few year light distances) twin precessing JETs spirals. These beams are made by tidal forces while stripping mass from large stellar companion feeding an inner BH accretion disk and an orthogonal accelerating twin JET. From it, the radio, X gamma JET emission. A couple of years ago H.E.S.S telescope as well as HAWC and LHAASO array detectors, discovered also the surprising signature of an unexpected far twin separated gamma beam at tens TeV energy. At a hundred light years distances from its central source. We suggest that it is the legacy of a past rare eruption, a century ago, of tens PeV (10^16 eV) RELATIVISTIC twin neutron beams. Their beta decay in flight at far distances, into proton, neutrino and in particular into tens TeV electrons, could feed the observed TeV gamma traces. They are originated by the same secondary tens TeV electrons emitting hard gamma, by Inverse Compton Scattering onto interstellar infrared photons.
[abstract 11 / 57] Yes (score: 5) - Title: Pulsar based modeling of point spread function of FERMI Large Area TelescopeAuthors: J. Blunier, A. Neronov, D. Semikoz,Comments: 9 pages, 9 figures, 1 tableSubjects: astro-ph.HECreated: 2026-02-16; Updated: 2026-02-17; Datestamp: 2026-02-17
Sensitivity of searches for extended emission around gamma-ray sources is naturally limited by the precision of the knowledge of the Point Spread Function (PSF) of gamma-ray telescopes. Inaccuracies in the PSF models of the FERMI Large Area Telescope (LAT) can potentially lead to false positive detections of source extension. We explore uncertainties in the FERMI/LAT PSF by comparing the PSF models provided by the FERMI/LAT Instrument Response Functions (IRFs) with signals of bright pulsars. We compare the analytical PSF models of FERMI/LAT IRFs with pulsar data and fit the pulsar data with the same analytical model as in the FERMI/LAT IRFs to derive an improved set of PSF parameters. We then apply this revised PSF parameterisation to the search of extended emission around a BLAZAR, Mrk 501. We find that the parameters of the analytical PSF models of FERMI/LAT IRFs are inconsistent with the pulsar data. We obtain an improved set of PSF parameters from the fits to pulsar data that is consistent with observations. We find no evidence of the previously reported extended signal around Mrk 501 if the revised PSF consistent with pulsar data is used in data analysis.
[abstract 12 / 57] Yes (score: 4) - Title: Dynamics of powerful RADIO GALAXiesAuthors: Ross J. Turner, Stanislav S. Shabala,Comments: 27 pages, 8 figures, 1 table; published in GalaxiesSubjects: astro-ph.GA astro-ph.HECreated: 2026-02-14; Updated: 2026-02-17; Datestamp: 2026-02-17
Analytical models describing the dynamics of lobed radio sources are essential for interpretation of the tens of millions of radio sources that will be observed by the Square Kilometre Array and pathfinder instruments. We propose that historical models can be grouped into two classes in which the forward expansion of the radio source is driven by either the JET momentum flux or lobe internal pressure. The most recent generation of analytical models combines these limiting cases for a more comprehensive description. We extend the mathematical formalism of historical models to describe source expansion in non-uniform environments, and directly compare different model classes with each other, and with hydrodynamic numerical simulations. We quantify differences in predicted observable characteristics for lobed radio sources due to the different model assumptions for their dynamics. We make our code for the historical models analysed in this review openly available to the community.
[abstract 13 / 57] Yes (score: 4) - Title: Hypothesis of a bi-isotropic-like plasma permeating the interstellar spaceAuthors: Filipe S. Ribeiro, Pedro D. S. Silva, Rodolfo Casana, Manoel M. Ferreira,Comments: 13 pages, 8 figuresSubjects: astro-ph.HE physics.plasm-phCreated: 2026-02-16; Updated: 2026-02-17; Datestamp: 2026-02-17
In this work, we study the propagation of electroMAGNETic waves in a MAGNETized chiral plasma that pervades the interstellar space. The Maxwell equations, supplemented by bi-isotropic-like constitutive relations, are rewritten to describe a cold, uniform, and collisionless plasma model that yields new collective electroMAGNETic modes for distinct pairs of refractive indices associated with right- and left-handed circularly polarized waves. We have investigated the optical behavior through the rotatory power (RP) and dichroism coefficient, reporting that the finite chiral parameter induces double RP sign reversal, an exotic optical signature that takes place in chiral dielectrics and rotating plasmas. In the low-frequency regime, a modified propagating helicon with right-handed circular POLARIZATION is obtained. Next, supposing that the interstellar medium behaves as a chiral bi-isotropic-like cold plasma, we employ Astrophysical data of radio pulsars to achieve upper limits on the MAGNEToelectric parameters magnitude. In particular, by using dispersion measure and rotation measure data from five pulsars, we constrain the magnitude of the chiral parameter to the order of $10^{-16}$ and $10^{-22}$, respectively.
[abstract 14 / 57] Yes (score: 4) - Title: A RELATIVISTIC treatment of accretion disk torques on extreme mass-ratio inspirals around non-spinning BLACK HOLEsAuthors: Abhishek Hegade K. R., Charles F. Gammie, Nicolás Yunes,Comments: 34 pages, 5 figures. Matches published version. Supplementary MATHEMATICA file available at https://github.com/AbhiHegade/Supplementary-Material-for-Disc-Torques-in-Schwarzschild-BackgroundSubjects: gr-qc astro-ph.HECreated: 2026-02-15; Updated: 2026-02-17; Datestamp: 2026-02-17
We develop a RELATIVISTICally accurate formalism to model the interaction between stellar mass compact objects embedded in thin accretion disks around a non-spinning supermassive BLACK HOLE, using tools from self-force theory and Hamiltonian perturbation theory. We then apply this formalism to analyze the evolution of a compact object on a nearly circular and equatorial orbit interacting with a thin equatorial disk. We provide analytic and RELATIVISTICally-accurate expressions for the rates of energy and angular momentum exchanged during interactions due to Lindblad and corotation resonances. Our results show that RELATIVISTIC corrections can enhance the magnitude of the torque by 1-2 orders of magnitude compared to purely Newtonian expressions when the orbit of the compact object is smaller than $10$ Schwarzschild radii of the supermassive BLACK HOLE. We also demonstrate that strong RELATIVISTIC shifts the inner Lindblad resonances closer to the compact object than the outer Lindblad resonances when the compact object is closer than 4 Schwarzschild radii to the supermassive BLACK HOLE, potentially leading to a reversal in the direction of the torque acting on the compact object. Finally, we provide a dephasing estimate and show that using the RELATIVISTIC torque formula is crucial to obtain reliable estimates for extreme mass ratio inspirals in orbits closer than 5 Schwarzschild radii to the supermassive BLACK HOLE. Our results highlight the importance of using RELATIVISTICally-accurate models of environmental interactions in extreme mass-ratio inspirals close to a supermassive BLACK HOLE.
[abstract 15 / 57] Yes (score: 4) - Title: Magnetic Field Line Chaos, Cantori, and Turnstiles in Toroidal PlasmasAuthors: Allen H Boozer,Comments:Subjects: physics.plasm-phCreated: 2026-02-15; Updated: 2026-02-17; Datestamp: 2026-02-17
The mathematical concepts of chaos, cartori, and turnstiles underlie a number of areas of tokamak and stellarator physics. Nevertheless, few authors have explicitly used these concepts in publications on fusion plasmas. The small number of plasma physicists who have an intuitive understanding of these concepts retards or blocks development in a number of areas: MAGNETic RECONNECTion, the most important electroMAGNETic correction to what are called electrostatic micro-instabilities, non-resonant divertors in stellarators, disruptions and damage from runaway electrons in tokamaks. Physicists become interested in new mathematical concepts when they give insights into and solutions to practical problems. The importance of this review is not only in explaining chaos, cartori, and turnstiles as mathematical concepts but also in illustrating their significance through applications.
[abstract 16 / 57] Yes (score: 4) - Title: Cygnus~X-3 as a PeVatron and the LHAASO 2025 dataAuthors: M. Kachelriess, E. Lammert,Comments: v2: 4 pages, added possibility of increased absorption in line-driven WR windSubjects: astro-ph.HECreated: 2026-02-16; Updated: 2026-02-17; Datestamp: 2026-02-17
We have recently argued that the high-mass X-ray binary Cygnus~X-3 can accelerate COSMIC RAYs (CR) beyond PeV energies. Meanwhile, the LHAASO collaboration published the measurement of an orbitally modulated photon flux from Cygnus~X-3 extending up to 4\,PeV. In this short extension of our previous work, we argue that these observations point towards CR acceleration in the JET, and secondary production in CRs scattering on gas from the wind and on stellar UV photons from the companion star. The latter channel leads naturally to a contribution to the photon flux peaking around PeV energies which is orbitally modulated. The fast drop in the flux of these photons below PeV energies may be caused by absorption on an increased density of background photons in a line-driven stellar wind.
[abstract 17 / 57] Yes (score: 4) - Title: Harmonic Analysis on Correlation for Gravitational-Wave Backgrounds of Arbitrary Polarization from Interfering Sources in Generic Dispersion RelationAuthors: Yan-Chen Bi, Yu-Mei Wu, Qing-Guo Huang,Comments: 11 pages, 3 figuresSubjects: gr-qc astro-ph.CO astro-ph.HECreated: 2026-02-14; Updated: 2026-02-17; Datestamp: 2026-02-17
The Hellings-Downs (HD) correlation serves as the fundamental benchmark for detecting the gravitational-wave background (GWB) in pulsar timing arrays (PTAs) within General Relativity (GR). However, this canonical signature relies on the idealization of a continuum of sources without interference. In realistic astrophysical scenarios dominated by supermassive BLACK HOLE binaries (SMBHBs), interference between discrete sources induces intrinsic deviations in the spatial correlation, which may mimic or obscure signatures of modified gravity. In this work, we derive the closed-form spatial correlation functions for a GWB with arbitrary POLARIZATION and generic GW dispersion relations, in the presence of source interference. Through a rigorous harmonic analysis, we demonstrate that source interference modifies the correlation shape but strictly preserves the lowest non-vanishing multipole moment characteristic of each POLARIZATION, specifically the quadrupole for tensor, dipole for vector, and monopole for scalar modes. The truncation at higher-order multipoles is governed by the interplay between pulsar distances and dispersion effects. Furthermore, we quantify the statistical degeneracy between interference-induced variation and modified gravity signatures. We conclude that access to only a single realization of the Universe imposes a fundamental theoretical limit on distinguishing modified gravity from GR using spatial correlations alone.
[abstract 18 / 57] Yes (score: 4) - Title: Tracing Fe K X-ray reverberation lag in the energy-resolved spectra of Narrow-line Seyfert 1 galaxy Ton S180Authors: Dilip Kumar Roy, Samuzal Barua, Ranjeev Misra, Rathin Sarma, V. Jithesh,Comments: Accepted for Publication in ApJ, 10 pages, 7 figures, 2 TablesSubjects: astro-ph.HECreated: 2026-02-15; Updated: 2026-02-17; Datestamp: 2026-02-17
We report the Fe K RELATIVISTIC reverberation feature for the first time in the Narrow-line Seyfert\,1 galaxy Ton\,S180. Using a long observation from {\it XMM-Newton} we find that the Fe K emission lag peaks at $117\pm49$ s in the lag energy spectrum computed for frequencies $(0.3-8.5) \times 10^{-4}$ Hz. The lag amplitude drops to $22.85\pm14.20$ s as the frequency increases to $(8.5-30) \times 10^{-4}$ Hz. The time-averaged spectrum of the source shows a relatively narrow Fe K line at $\sim6.4$ keV, resulting in BLACK HOLE spin to be low ($a=\rm 0.43_{-0.14}^{+0.10}$) found from the reflection modelling. We perform general RELATIVISTIC transfer function modelling of the lag energy spectra individually. This provides an independent timing-based measure of the spin at $a=0.30_{-0.17}^{+0.34}$, and BLACK HOLE mass $M_{\rm BH} = 0.29_{-0.16}^{+0.01}\times10^8M_{\odot}$, comparable to the previous measurement, and height of the corona $h = 2.59_{-0.33}^{+5.17}r_{\rm g}$. Further, we observe that the Fe K lag and the BLACK HOLE mass fit well in the linear lag-mass relation shown by other Seyfert 1 galaxies.
[abstract 19 / 57] Yes (score: 4) - Title: 4U 1556-60 as a very faint neutron star X-ray binary at 700 pc with an undetected radio JETAuthors: Eliot C. Pattie, Thomas J. Maccarone, Thomas Russell, Matteo Bachetti, Nathalie Degenaar, Thomas Kupfer,Comments: Accepted for publication in A&ASubjects: astro-ph.HECreated: 2026-02-16; Updated: 2026-02-17; Datestamp: 2026-02-17
4U 1556-60 is a low-mass X-ray binary that was discovered more than 50 years ago as a persistent X-ray source; however, very little was known about it. Recently, Gaia obtained a parallax for the optical counterpart that places 4U 1556-60 at a distance of only about 700 pc, making it one of the closest X-ray binaries known to date. This close distance drastically alters what was previously assumed about the source. We revisit 4U 1556-60 in light of the newly determined distance of 700 pc, reinterpreting its literature and presenting new X-ray and radio observations to better understand various characteristics of the system. We conclude that a scenario in which 4U 1556-60 is a candidate ultracompact neutron star X-ray binary at a distance of ~700 pc is able to explain the observed properties of the source. It resides at a persistent X-ray luminosity of ~2x10^34 erg/s, an unusual value for a typical X-ray binary, but similar to several ultracompact systems. The ratio of the X-ray to optical luminosity is very high, also suggesting a physically small accretion disk. The radio JET is undetected with a very deep upper limit of 3x10^25 erg/s, which is about 10^3 times fainter than the expected BLACK HOLE JET correlation, strongly indicating a neutron star accretor. The X-ray spectrum is dominated by a power law, and the X-ray timing properties are also consistent with observations of other very low accretion rate X-ray binaries. No spin or orbital periodicity are found in the X-ray data. Future observations, especially to determine its orbital period, will further aid in understanding 4U 1556-60.
[abstract 20 / 57] (score: 3) - Title: Stringent Tests of Lorentz Invariance Violation from LHAASO Observations of GRB 221009AAuthors: The LHAASO Collaboration, Zhen Cao, F. Aharonian, Axikegu, Y. X. Bai, Y. W. Bao, D. Bastieri, X. J. Bi, Y. J. Bi, W. Bian, A. V. Bukevich, Q. Cao, W. Y. Cao, Zhe Cao, J. Chang, J. F. Chang, A. M. Chen, E. S. Chen, H. X. Chen, Liang Chen, Lin Chen, Long Chen, M. J. Chen, M. L. Chen, Q. H. Chen, S. Chen, S. H. Chen, S. Z. Chen, T. L. Chen, Y. Chen, N. Cheng, Y. D. Cheng, M. Y. Cui, S. W. Cui, X. H. Cui, Y. D. Cui, B. Z. Dai, H. L. Dai, Z. G. Dai, Danzengluobu, X. Q. Dong, K. K. Duan, J. H. Fan, Y. Z. Fan, J. Fang, J. H. Fang, K. Fang, C. F. Feng, H. Feng, L. Feng, S. H. Feng, X. T. Feng, Y. Feng, Y. L. Feng, S. Gabici, B. Gao, C. D. Gao, Q. Gao, W. Gao, W. K. Gao, M. M. Ge, L. S. Geng, G. Giacinti, G. H. Gong, Q. B. Gou, M. H. Gu, F. L. Guo, X. L. Guo, Y. Q. Guo, Y. Y. Guo, Y. A. Han, M. Hasan, H. H. He, H. N. He, J. Y. He, Y. He, Y. K. Hor, B. W. Hou, C. Hou, X. Hou, H. B. Hu, Q. Hu, S. C. Hu, D. H. Huang, T. Q. Huang, W. J. Huang, X. T. Huang, X. Y. Huang, Y. Huang, X. L. Ji, H. Y. Jia, K. Jia, K. Jiang, X. W. Jiang, Z. J. Jiang, M. Jin, M. M. Kang, I. Karpikov, D. Kuleshov, K. Kurinov, B. B. Li, C. M. Li, Cheng Li, Cong Li, D. Li, F. Li, H. B. Li, H. C. Li, Jian Li, Jie Li, K. Li, S. D. Li, W. L. Li, X. R. Li, Xin Li, Y. Z. Li, Zhe Li, Zhuo Li, E. W. Liang, Y. F. Liang, S. J. Lin, B. Liu, C. Liu, D. Liu, D. B. Liu, H. Liu, H. D. Liu, J. Liu, J. L. Liu, M. Y. Liu, R. Y. Liu, S. M. Liu, W. Liu, Y. Liu, Y. N. Liu, Q. Luo, Y. Luo, H. K. Lv, B. Q. Ma, L. L. Ma, X. H. Ma, J. R. Mao, Z. Min, W. Mitthumsiri, H. J. Mu, Y. C. Nan, A. Neronov, L. J. Ou, P. Pattarakijwanich, Z. Y. Pei, J. C. Qi, M. Y. Qi, B. Q. Qiao, J. J. Qin, A. Raza, D. Ruffolo, A. Sáiz, M. Saeed, D. Semikoz, L. Shao, O. Shchegolev, X. D. Sheng, F. W. Shu, H. C. Song, Yu. V. Stenkin, V. Stepanov, Y. Su, D. X. Sun, Q. N. Sun, X. N. Sun, Z. B. Sun, J. Takata, P. H. T. Tam, Q. W. Tang, R. Tang, Z. B. Tang, W. W. Tian, C. Wang, C. B. Wang, G. W. Wang, H. G. Wang, H. H. Wang, J. C. Wang, Kai Wang, L. P. Wang, L. Y. Wang, P. H. Wang, R. Wang, W. Wang, X. G. Wang, X. Y. Wang, Y. Wang, Y. D. Wang, Y. J. Wang, Z. H. Wang, Z. X. Wang, Zhen Wang, Zheng Wang, D. M. Wei, J. J. Wei, Y. J. Wei, T. Wen, C. Y. Wu, H. R. Wu, Q. W. Wu, S. Wu, X. F. Wu, Y. S. Wu, S. Q. Xi, J. Xia, G. M. Xiang, D. X. Xiao, G. Xiao, Y. L. Xin, Y. Xing, D. R. Xiong, Z. Xiong, D. L. Xu, R. F. Xu, R. X. Xu, W. L. Xu, L. Xue, D. H. Yan, J. Z. Yan, T. Yan, C. W. Yang, C. Y. Yang, F. Yang, F. F. Yang, L. L. Yang, M. J. Yang, R. Z. Yang, W. X. Yang, Y. H. Yao, Z. G. Yao, L. Q. Yin, N. Yin, X. H. You, Z. Y. You, Y. H. Yu, Q. Yuan, H. Yue, H. D. Zeng, T. X. Zeng, W. Zeng, M. Zha, B. B. Zhang, F. Zhang, H. Zhang, H. M. Zhang, H. Y. Zhang, J. L. Zhang, Li Zhang, P. F. Zhang, P. P. Zhang, R. Zhang, S. B. Zhang, S. R. Zhang, S. S. Zhang, X. Zhang, X. P. Zhang, Y. F. Zhang, Yi Zhang, Yong Zhang, B. Zhao, J. Zhao, L. Zhao, L. Z. Zhao, S. P. Zhao, X. H. Zhao, F. Zheng, W. J. Zhong, B. Zhou, H. Zhou, J. N. Zhou, M. Zhou, P. Zhou, R. Zhou, X. X. Zhou, B. Y. Zhu, C. G. Zhu, F. R. Zhu, H. Zhu, K. J. Zhu, Y. C. Zou, X. Zuo,Comments: 10pages, 7 figuresSubjects: astro-ph.HE gr-qc hep-ph hep-thCreated: 2026-02-13; Updated: 2026-02-17; Datestamp: 2026-02-17
On October 9, 2022, the Large High Altitude Air Shower Observatory (LHAASO) reported the observation of the very early TeV afterglow of the brightest-of-all-time GRB 221009A, recording the highest photon statistics in the TeV band ever from a GAMMA-RAY BURST. We use this unique observation to place stringent constraints on an energy dependence of the speed of light in vacuum, a manifestation of Lorentz invariance violation (LIV) predicted by some quantum gravity (QG) theories. Our results show that the 95% confidence level lower limits on the QG energy scales are $E_{\mathrm{QG},1}>10$ times of the Planck energy $E_\mathrm{Pl}$ for the linear, and $E_{\mathrm{QG},2}>6\times10^{-8}E_\mathrm{Pl}$ for the quadratic LIV effects, respectively. Our limits on the quadratic LIV case improve previous best bounds by factors of 5--7.
[abstract 21 / 57] (score: 3) - Title: Compression fronts from fast radio burstsAuthors: Andrei M. Beloborodov,Comments: 27 pages, 10 figures, ApJ, in pressSubjects: astro-ph.HECreated: 2026-02-16; Updated: 2026-02-17; Datestamp: 2026-02-17
When a fast radio burst (FRB) expands from its source through a surrounding tenuous plasma, it strongly heats and compresses the plasma at radii up to $\sim 10^{14}$cm. The likely central engines of FRBs are MAGNETars, and their ambient plasma at radii $r\gg 10^{10}$cm is a MAGNETized $e^\pm$ wind. We formulate basic equations of the FRB-plasma interaction, solve them numerically, and describe the physical picture of the interaction. We find the following: (1) FRBs emitted at $r
[abstract 22 / 57] (score: 3) - Title: A RELATIVISTIC treatment of accretion disk torques on extreme mass ratio inspirals around spinning BLACK HOLEsAuthors: Abhishek Hegade K. R., Charles F. Gammie, Nicolás Yunes,Comments: Matches published version. 12 pages, 5 figures. Supplementary material available at https://github.com/AbhiHegade/Supplementary-Material-for-Disc-Torques-in-Schwarzschild-Background. Comments are welcome!Subjects: gr-qcCreated: 2026-02-15; Updated: 2026-02-17; Datestamp: 2026-02-17
We model the motion of a small compact object on a nearly circular orbit around a spinning supermassive BLACK HOLE, which is also interacting with a thin equatorial accretion-disk surrounding the latter, through tools from self-force and Hamiltonian perturbation theory. We provide an analytical and RELATIVISTICally-accurate formalism to calculate the rate of energy and angular momentum exchanged at Lindblad resonances. We show that strong RELATIVISTIC effects can potentially cause a reversal in the direction of the torque on the small compact object if the surface density gradient is not too large. We analytically explore the dependence of the torque reversal location on the spin of the supermassive BLACK HOLE and demonstrate that the ratio of the reversal location to the innermost stable circular orbit is approximately insensitive to the spin of the supermassive BLACK HOLE. Our results show that RELATIVISTIC torques can be 1--2 order of magnitude larger than the Newtonian torque routinely used in the literature to model disk/small-compact-object interactions close to the supermassive BLACK HOLE. Our results highlight the importance of including RELATIVISTIC effects when modeling environmental effects in extreme mass-ratio inspirals.
[abstract 23 / 57] (score: 3) - Title: DIPLODOCUS II: Implementation of transport equations and test cases relevant to micro-scale physics of JETted astrophysical sourcesAuthors: Christopher N. Everett, Marc Klinger-Plaisier, Garret Cotter,Comments: 22 pages, 23 figures. Published in the Open Journal of AstrophysicsSubjects: astro-ph.HECreated: 2026-02-16; Updated: 2026-02-17; Datestamp: 2026-02-17
DIPLODOCUS (Distribution-In-PLateaux methODOlogy for the CompUtation of transport equationS) is a framework being developed for the mesoscopic modelling of astrophysical systems via the transport of particle distribution functions through the seven dimensions of phase space, including continuous forces and discrete interactions between particles. Following Paper I, which details the mathematical background, this second paper provides an overview of the numerical implementation in the form of the code package Diplodocus$.$jl, written in Julia, including the description of a novel Monte-Carlo sampling technique for the pre-computation of anisotropic collision integrals. In addition to the discussion of numerical implementation, a selection of test cases are presented to examine the package's capabilities. These test cases focus on micro-scale physical effects: binary collisions, emissive interactions, and external forces that are relevant to the modelling of JETted astrophysical sources, such as Active Galactic Nuclei and X-Ray Binaries.
[abstract 24 / 57] (score: 3) - Title: Mode Energy Partition in Partially Ionized Compressible MHD TurbulenceAuthors: Yue Hu,Comments: The 17th International Conference on Numerical Modeling of Space Plasma Flows 2025Subjects: astro-ph.GACreated: 2026-02-14; Updated: 2026-02-17; Datestamp: 2026-02-17
We investigate how neutral-ion collisional damping modifies the spectral properties and energy partition of compressible MHD turbulence using a suite of 3D two-fluid simulations. By systematically varying the neutral-ion coupling strength and decomposing the turbulent velocity field into Alfvén, slow, and fast (POLARIZATION) modes, we quantify how each mode responds to the transition from strong to weak coupling. In the strong-coupling regime, the Alfvén and slow modes follow nearly Kolmogorov $k^{-5/3}$ spectra and dominate the kinetic energy budget, while fast modes exhibit a steeper spectrum and contribute $\sim$10\% of the total energy. As the coupling weakens and neutral-ion damping becomes significant, all mode spectra steepen, approaching a dissipation-dominated $k^{-4}$ spectrum, except that the slope mode's spectrum parallel to the mean MAGNETic field has a power-law slope shallower than -4. While the total kinetic energy is reduced in the weak coupling regime, the slow-mode energy fraction increases substantially toward small scales, whereas the Alfvén-mode fraction decreases correspondingly. In contrast, the fast-mode energy fraction remains largely insensitive to coupling strength. These results demonstrate that partial ionization not only steepens the turbulent spectra but also reshapes the mode energy distribution, enhancing the relative importance of the slow mode while suppressing Alfvén mode in the damping regime. Our findings have important implications for turbulence-driven processes in the partially ionized interstellar medium, including cosmic-ray transport and acceleration.
[abstract 25 / 57] (score: 3) - Title: Dense gas linked to star-forming regions photoionised by embedded GAMMA-RAY BURSTsAuthors: Aishwarya Linesh Thakur, Luigi Piro, Alfredo Luminari, Fabrizio Nicastro, Sandra Savaglio, Yair Krongold, Bruce Gendre,Comments: 79 pages, 41 figures, 6 tables. Published in Nature Astronomy with minor editorial changesSubjects: astro-ph.HECreated: 2026-02-16; Updated: 2026-02-17; Datestamp: 2026-02-17
The 1-100 pc region embedding long-duration GAMMA-RAY BURSTs (lGRBs) has been hitherto unexplored, as extremely high ionisation by the GRB prevents application of optical absorption spectroscopy on such distances. We show that the GRB ionising flux imprints a unique time- and spatially-dependent ionisation structure on the gas, that can be probed by X-ray absorption. Application of this model to a selected sample of 7 bright GRB X-ray afterglow spectra observed by \textit{XMM-Newton} EPIC-pn enables an independent, quantitative estimation of the density (log(n) $\sim$ 2-4) and distances (5-100 pc) of the ionized absorber directly from the GRB X-ray spectrum, thereby allowing us to locate the absorbing medium of this representative sample of long GRBs in the region of the density-size diagram populated by star-forming regions versus other gravitationally bound objects in the Universe. Our results provide one of the most direct links between lGRBs and STAR FORMATION and open the potential of high-resolution X-ray spectroscopy as a powerful probe of star-forming regions that embed GRBs up to the highest redshifts.
[abstract 26 / 57] (score: 3) - Title: Searching for DARK MATTER signals with high energy astrophysical neutrinos in IceCubeAuthors: Khushboo Dixit, Gopolang Mohlabeng, Soebur Razzaque,Comments: 15 pages, 6 figures, added some referencesSubjects: astro-ph.HE hep-phCreated: 2026-02-16; Updated: 2026-02-17; Datestamp: 2026-02-17
High-energy neutrinos provide a potentially powerful and distinctive probe for DARK MATTER (DM) - neutrino interactions, particularly in environments with enhanced DM densities, such as the DM spikes predicted to form around supermassive BLACK HOLEs (SMBHs) at the center of ACTIVE GALACTIC NUCLEi (AGN). Recent observations by the IceCube Neutrino Observatory, which identified four AGN, namely TXS 0506+056, NGC 1068, PKS 1424+240, and NGC 4151 as neutrino sources, provide a unique opportunity to search for signatures of these interactions. In this study, we use IceCube data to derive the most stringent constraints to date on both the energy-dependent and energy-independent DM-neutrino scattering cross-sections. We perform a statistical analysis using data from individual sources as well as a combined (stacked) analysis of all four sources. Our strongest limits arise from the stacking analysis, yielding an upper bound of $σ_{0} \lesssim 8\times 10^{-39}$ cm$^2$ for an energy-independent cross-section and $σ_{0} \lesssim 10^{-39}$ cm$^2$ for a linearly energy-dependent cross-section, both at 90\% confidence level, particularly in scenarios involving the adiabatic growth of BLACK HOLEs.
[abstract 27 / 57] (score: 3) - Title: The measurable impact of the 2pN spin-dependent accelerations on the JET precession of M87$^\ast$Authors: Lorenzo Iorio,Comments: LaTex2e, 26 pages, no tables, 3 figures. References added. Calculation with cartesian coordinates and one figure addedSubjects: gr-qc astro-ph.GACreated: 2026-02-15; Updated: 2026-02-17; Datestamp: 2026-02-17
Motivated by recent accurate measurements of disk/JET coprecessions around some galactic supermassive BLACK HOLEs, the accelerations experienced by an uncharged, spinless object in the Kerr metric, written in harmonic coordinates, are analytically calculated up to the formal second post-Newtonian order. To such a level, some new accelerations make their appearance. They are proportional to even and odd powers of the hole's angular momentum. Their counterparts are not known where the primary is a material body. After expressing them in a coordinate-independent, vector form valid for any orientations of the hole's spin axis in space, their orbital effects are perturbatively worked out in terms of the particle's Keplerian orbital elements. The resulting expressions, averaged over one orbital revolution, are valid for generic shapes and inclinations of the orbit. The orbital plane's precession proportional to the first power of the hole's angular momentum and to the reciprocal of the fourth power of the speed of light amounts to about twenty per cent of the corresponding Lense-Thirring effect. The latter is believed to be the cause of the accurately measured disk/JET precessional phenomenology, currently measured to a few per cent accuracy. Although at a lesser extent, also the precession proportional to the second power of the hole's spin and to the reciprocal of the fourth power of the speed of light is measurable. Allowed domains in the parameter space of the JET precession around M87$^\ast$ are displayed.
[abstract 28 / 57] (score: 3) - Title: Direct pathway to the Early Supermassive Black Holes: A Red Super-Eddington Quasar in a Massive Starburst Host at $z=7.2$Authors: Qinyue Fei, Seiji Fujimoto, Gabriel Brammer, Ruancun Li, Luis C. Ho, Volker Bromm, Javier Álvarez-Márquez, Yoshihisa Asada, Guillermo Barro, Luis Colina, Pratika Dayal, Steven L. Finkelstein, Johan P. U. Fynbo, Michele Ginolfi, Kohei Inayoshi, Vasily Kokorev, Gene C. K. Leung, Jorryt Matthee, Romain A. Meyer, Rohan P. Naidu, Masafusa Onoue, Pablo G. Pérez-González, Charles L. Steinhardt, Francesco Valentino, Fabian Walter, Mengyuan Xiao, Haowen Zhang,Comments: 26 pages, 12 figures, 2 tables. Submitted to ApJ. Comments are welcome!Subjects: astro-ph.GACreated: 2026-02-16; Updated: 2026-02-17; Datestamp: 2026-02-17
We present a panchromatic optical-mm characterization of GNz7q, a recently identified X-ray weak, rapidly growing red QUASAR embedded within a dusty starburst galaxy at $z=7.1899$, using the full suite of JWST/NIRCam, NIRSpec, MIRI, and archival NOEMA observations. Our deep NIRSpec/G395M spectroscopy reveals unambiguous broad Balmer emission (FWHM $=2221\pm20$kms$^{-1}$), confirming a super-Eddington accreting BLACK HOLE ($λ_{\rm Edd}=2.7\pm0.4$) with a mass of $\log(M_{\rm BH}/M_{\odot})=7.55\pm0.34$, using accretion-rate corrected BH mass estimators. After subtracting the point source, we robustly detect stellar emission from the host galaxy across multiple NIRCam and MIRI filters. Out joint morphological-spectral analysis yields a stellar mass of $\log (M_*/M_\odot)=10.5\pm0.4$ and an intense STAR FORMATION rate of ${\rm SFR}=330\pm97\,M_\odot\,\rm yr^{-1}$, confirming the host as a massive, dusty starburst galaxy. We find that GNz7q lies on the local $M_{\rm BH}$-$M_*$ relation ($M_{\rm BH}/M_*\simeq 0.001$) and is well positioned to evolve into the locus of massive SDSS QUASARs with $\log (M_{\rm BH}/M_\odot)\approx 9$ and $M_*\approx 10^{11}\,M_\odot$ at $z\sim 6$, owing to its remarkably rapid growth in both the BLACK HOLE and its host galaxy. This stands in stark contrast to many recently reported JWST AGN populations at similar redshifts, including the little red dots (LRDs), whose weak or undetected STAR FORMATION makes it difficult for them to grow into the massive galaxies hosting SDSS-like QUASARs. These results suggest that GNz7q marks as a rare, pivotal phase of early BH-galaxy co-eolution, plausibly providing a crucial direct pathway to the supermassive BLACK HOLE systems within the first billion years of the Universe.
[abstract 29 / 57] (score: 3) - Title: ARCHITECTS II: Impact of subgrid physics on the observable properties of the circumgalactic mediumAuthors: Maxime Rey, Jérémy Blaizot, Taysun Kimm, Joakim Rosdahl, Léo Michel-Dansac, Valentin Mauerhofer,Comments: 21 pages, 12 figures, submitted to MNRASSubjects: astro-ph.GACreated: 2026-02-13; Updated: 2026-02-17; Datestamp: 2026-02-17
Galaxy evolution is driven by STAR FORMATION and stellar feedback on scales unresolved by current high-resolution cosmological simulations, requiring robust subgrid models. However, these models remain degenerate, often calibrated primarily to match observed stellar masses. To explore these degeneracies, we conduct three state-of-the-art cosmological zoom-in simulations of the same galaxy, each incorporating different subgrid models: mechanical feedback, a combination of mechanical and thermal feedback, and delayed cooling. We compare their circumgalactic media (CGM) through QUASAR absorption sightlines of HI, MgII, CIV, and OVI. Our findings demonstrate that despite producing galaxies with the same stellar masses, the models lead to distinct feedback modes and CGM properties. Column densities and covering fractions serve as effective diagnostics of subgrid models, with all four ions providing strong constraints as they trace diverse gas phases, exhibit complementary spatial distributions, and originate from different mechanisms. Although all simulations bracket observed column density distributions, direct comparisons are limited by scarce detections and significant scatter in absorption strengths. Covering fractions of weak absorbers provides the most robust constraints. All models fail to reproduce HI and MgII covering fractions, and delayed cooling overproduces OVI covering fractions, while the other models underproduce them. The simulation including mechanical feedback reproduces the observed CIV covering fractions well, whereas the other models show slight offsets. We argue that this discrepancy is likely driven by unresolved thermal structures for HI and MgII, and insufficient metals for CIV and OVI, arising from missing physics such as AGNs or COSMIC RAYs.
[abstract 30 / 57] (score: 3) - Title: Superorbital Phase Evolution and a Soft-Hard X-ray Phase Shift in LMC X-4Authors: Yi Chou,Comments: 18 pages, 7 figures, accepted for publication by ApJSubjects: astro-ph.HECreated: 2026-02-13; Updated: 2026-02-17; Datestamp: 2026-02-17
The superorbital period of LMC X-4 is among the most stable known in Roche-lobe overflow, high-mass X-ray binaries. We analyzed 33 years of monitoring data from the Compton Gamma Ray Observatory Burst and Transient Source Experiment (CGRO BATSE), the Rossi X-ray Timing Explorer All-Sky Monitor (RXTE ASM), the Neil Gehrels SWIFT Burst Alert Telescope (SWIFT BAT), the Monitor of All-sky X-ray Image Gas Slit Camera (MAXI GSC), and the FERMI Gamma-ray Burst Monitor (FERMI GBM). The measured phases show a smooth long-term trend with superposed systematic fluctuations. Fits with cubic, quartic, and sinusoidal models indicate that the quartic and sinusoidal forms provide significantly better descriptions, with the sinusoidal model yielding an $8900^{+210}_{-230}$-day modulation. Such a long timescale is unlikely to arise from orbital motion around a tertiary companion. The fluctuations resemble stochastic, glitch-like events on several-hundred-day timescales. Their rms period variation exceeds that of the smooth trend, yet the total rms period variation over 33 years remains only 0.55\%, demonstrating the exceptional stability of the superorbital period. During MJD 57000-60461, we detect a phase offset of 0.044$\pm$0.010 cycles between the soft and hard X-ray bands. This offset can be reproduced by including a higher-harmonic term in the azimuthal disk model, allowing a transition from antisymmetric to asymmetric structure. A contemporaneous decline in the hard X-ray flux suggests a partial obscuration of the emission region, similar to the anomalous low state in Her X-1. This evolving-disk scenario may also explain the superorbital phase shift previously reported in Her X-1.
[abstract 31 / 57] (score: 3) - Title: Leveling of MHD turbulence imbalance in shear flowsAuthors: M. Kavtaradze, G. Mamatsashvili, G. Chagelishvili, E. Uchava,Comments: 7 pages, 4 figures, submitted to Physical Review JournalsSubjects: physics.space-ph astro-ph.SR physics.flu-dyn physics.plasm-phCreated: 2026-02-13; Updated: 2026-02-17; Datestamp: 2026-02-17
We investigate MAGNETohydrodynamic (MHD) turbulence in plane shear flows with a streamwise background MAGNETic field in the super-Alfvénic regime. We show that the large-scale velocity shear suppresses turbulence imbalance, driving the system toward a balanced state -- the energies of counter-propagating Alfvén waves become essentially equal, even at initially perfectly imbalanced Alfvénic turbulence. This balancing is due to the shear-induced linear non-modal dynamics of Alfvén waves, including their transient growth and over-reflection. This linear route to balancing turbulence is new -- fundamentally different from nonlinear ones operative in shearless MHD turbulence -- and have direct implications for understanding balanced/imbalanced MHD turbulence in the solar wind, which is modeled as a shear flow in a thermodynamically complex plasma.
[abstract 32 / 57] (score: 3) - Title: Detection of Cyclotron Absorption in the Radio Emission of GPM 1839-10Authors: Yunpeng Men, Ewan Barr, Yuanhong Qu, Csanad Horvath, Jinchen Jiang, Gregory Desvignes, Natasha Hurley-Walker, Michael Kramer, Rui Luo, Samuel J. McSweeney, Jason Wu,Comments: 9 pages, 7 figures; Accepted for publication in SCPMASubjects: astro-ph.HECreated: 2026-02-14; Updated: 2026-02-17; Datestamp: 2026-02-17
GPM 1839-10 is an intriguing long-period radio transient (LPT), distinguished by its activity spanning at least three decades and its highly unusual emission characteristics. These features include orthogonal POLARIZATION mode (OPM) switches, down-drifting sub-structures, and distinct linear-to-circular POLARIZATION conversion behaviors. In this work, we present follow-up observations utilizing the FAST telescope at L-band, yielding a total of seven detected radio pulses. We find a consistent association between OPM switches and a decrease in polarized intensity. This feature strongly supports the hypothesis that the OPM switches are generated by the incoherent summation of OPMs. Our measured Rotation Measures (RMs) are consistent with previous observations, indicating that the MAGNETo-ionic environment is stable. If the source is in a binary system, such stability suggests it may host a weakly MAGNETized companion. Crucially, we firstly observe clear evidence of a cyclotron absorption feature in one radio pulse, a signature rarely observed in radio sources. This feature allows us to infer that the MAGNETic field strength at the absorption site has a lower limit of tens of Gauss, which is necessary for the phenomenon to occur. This characteristic can be explained in a scenario where GPM 1839-10 possesses a weakly MAGNETized companion star.
[abstract 33 / 57] (score: 3) - Title: High Energy Emission from the Galactic CenterAuthors: Andrea Goldwurm, Maïca Clavel, Stefano Gabici, Régis Terrier,Comments: Review paper (61 pages, 26 figures), accepted for publication in Reviews of Modern Physics on 19 December, 2025. Expected publication in RMP Vol. 98 Iss. 2, Apr-Jun 2026Subjects: astro-ph.HECreated: 2026-02-15; Updated: 2026-02-17; Datestamp: 2026-02-17
The center of the Galaxy is a prominent source in X-rays and gamma-rays. The study of its high-energy (HE) emission is crucial in understanding the physical phenomena taking place in this dense and extreme environment, where the closest supermassive BLACK HOLE (SMBH) to us, Sgr A*, is lurking nearly invisible, today, in most of the energy spectrum. These phenomena are probably common to other galactic nuclei and may explain the feedback processes between nuclear regions and galaxies, so important for the overall evolution of the Universe. The Galactic center HE emission is very complex and consists of both thermal and non thermal radiation produced by compact and extended sources, surrounded by more diffuse components. All these objects and media are interacting with each other in the narrow and dense Central Molecular Zone (CMZ). Some of them also show relevant extensions towards the Galactic poles, indicating energetic outflows that seem to link the center to the recently observed large Galactic polar structures. In spite of the fundamental advances obtained in the last twenty five years with the most sensitive X-ray and gamma-ray observatories, several questions remain open to investigations. We review here the main observational results and the open issues on the high-energy diagnostics of the Galactic nuclear activity, focusing on processes that take place in the CMZ, and in particular discussing the role of the present and past SMBH activities in powering this region and possibly the whole Galaxy.
[abstract 34 / 57] (score: 3) - Title: Nonlinear diffusive shock acceleration with upstream escape reproduces DAMPE observationsAuthors: Han-Xiang Hu, Xing-Jian Lv, Xiao-Jun Bi, Tian-Lu Chen, Kun Fang, Peng-Fei Yin,Comments: 10 pages, 3 figuresSubjects: astro-ph.HECreated: 2026-02-15; Updated: 2026-02-17; Datestamp: 2026-02-17
We develop a self-consistent nonlinear extension of diffusive shock acceleration that incorporates COSMIC RAY (CR) backreaction on the shock precursor together with a physically motivated upstream-escape mechanism that produces an exponential high energy cutoff. The CR pressure gradient decelerates the upstream flow facing the shock wave, generating an extended precursor in which higher rigidity particles sample a larger cumulative velocity gradient and thereby acquire a progressively harder spectrum. Finite-size/escape effects are modeled by a momentum-dependent loss term, which naturally terminates acceleration and steepens the spectrum near the cutoff. The precursor compression ratio is not imposed as a closure condition but is determined dynamically by requiring consistency between the injection rate inferred from thermal leakage at the subshock and the injection strength demanded by the nonlinear shock modification, with CR-driven wave heating providing stabilizing negative feedback. Applying the model to young SUPERNOVA-remnant-like parameters and standard one-zone Galactic diffusion, we reproduce the main features of the latest DAMPE proton spectrum: gradual hardening from hundreds of GeV to multi-TeV energies and a subsequent exponential cutoff at tens of TeV. The resulting spectral evolution follows directly from the competition between precursor-mediated nonlinear feedback and upstream escape.
[abstract 35 / 57] (score: 3) - Title: Exploring the MAGNETic field of the ultraluminous X-ray pulsar NGC 4631 X-8Authors: Amar Deo Chandra,Comments: 9 pages, 4 figuresSubjects: astro-ph.HECreated: 2026-02-16; Updated: 2026-02-17; Datestamp: 2026-02-17
NGC 4631 X-8 is an ultraluminous X-ray pulsar (ULXP) having a spin period of about 9.7 s, discovered using XMM-Newton observations in 2025. The pulsar is known to show one of the largest spin-up rates ($\sim 9.6 \times 10^{-8}$ s s$^{-1}$) among the ULXP population. We explore the surface MAGNETic field of the neutron star in this source using different models, and find that the inferred MAGNETic field lies in the range of about $0.3-2 \times 10^{14}$G. We study the long-term MAGNETic field and spin period evolution of the pulsar assuming steady accretion using prevalent theoretical mechanisms and find that the pulsar will evolve to become a millisecond pulsar having decayed MAGNETic field of about $\sim 10^{9}$G in about a million years. The scenario of the formation of a millisecond pulsar is also probed using an estimate of the super-Eddington duty cycle of about 14% from the literature, which suggests that the neutron star would accrete sufficient matter to become a recycled millisecond pulsar. Exploring the MAGNETic field as well as the spin period evolution properties of ULXPs may enable us to understand the poorly understood evolutionary features of ULXPs, shed light on one of the pathways of millisecond pulsar formation and also help us to understand transient super-Eddington accretion phases in newborn MAGNETars, which are believed to power energetic events such as long GAMMA-RAY BURSTs and Type I superluminous SUPERNOVAe.
[abstract 36 / 57] (score: 2) - Title: Cool-Core Destruction in Merging Clusters with AGN Feedback and Radiative CoolingAuthors: Shuang-Shuang Chen, Hsiang-Yi Karen Yang, Hsi-Yu Schive, John ZuHone, Massimo Gaspari,Comments: 21 pages, 10 figures. Accepted for publication in ApJSubjects: astro-ph.CO astro-ph.GACreated: 2026-02-13; Updated: 2026-02-17; Datestamp: 2026-02-17
The origin of cool-core (CC) and non-cool-core (NCC) dichotomy of galaxy clusters remains uncertain. Previous simulations have found that cluster mergers are effective in destroying CCs but fail to prevent overcooling in cluster cores when radiative cooling is included. Feedback from ACTIVE GALACTIC NUCLEi (AGN) is a promising mechanism for balancing cooling in CCs; however, the role of AGN feedback in CC/NCC transitions remains elusive. In this work, we perform three-dimensional binary cluster merger simulations incorporating AGN feedback and radiative cooling, aiming to investigate the heating effects from mergers and AGN feedback on CC destruction. We vary the mass ratio and impact parameter to examine the entropy evolution of different merger scenarios. We find that AGN feedback is essential in regulating the merging clusters, and that CC destruction depends on the merger parameters. Our results suggest three scenarios regarding CC/NCC transitions: (1) CCs are preserved in minor mergers or mergers that do not trigger sufficient heating, in which cases AGN feedback is crucial for preventing the cooling catastrophe; (2) CCs are transformed into NCCs by major mergers during the first core passage, and AGN feedback is subdominant; (3) in major mergers with a large impact parameter, mergers and AGN feedback operate in concert to destroy the CCs.
[abstract 37 / 57] (score: 2) - Title: The spin-orbit alignment hypothesis in millisecond pulsarsAuthors: Alexandra Lorange, Jérôme Pétri, Mattéo Sautron, Vincent Vigon,Comments: Accepted by A&ASubjects: astro-ph.HECreated: 2026-02-16; Updated: 2026-02-17; Datestamp: 2026-02-17
Millisecond pulsars (MSPs) are spun up during their accretion phase in a binary system. The exchange of angular momentum between the accretion disk and the star tends to align the spin and orbital angular momenta on a very short time scale compared to the accretion stage. In this work, we study a subset of $γ$-ray MSPs in binaries for which the orbital inclination angle $i$ has been accurately constrained thanks to the Shapiro delay measurements. Our goal is to constrain the observer viewing angle $ζ$ and to check whether it agrees with the orbital inclination angle $i$, in other words if $ζ\approx i$. We use a Bayesian inference technique to fit the MSP $γ$-ray light curves based on the third $γ$-ray pulsar catalogue (3PC). The emission model relies on the striped wind model deduced from force-free neutron star MAGNETosphere simulations. We found good agreement between the two angles $i$ and $ζ$ for a significant fraction of our sample, about four fifth, confirming the spin-orbit alignment scenario during the accretion stage. However about one fifth of our sample deviates significantly from this alignment. The reasons are manifold: either the $γ$-ray fit is not reliable or some precession and external torque avoid an almost perfect alignment.
[abstract 38 / 57] (score: 2) - Title: Impact of thermal effects on prompt-collapse binary neutron star mergersAuthors: Carolyn A. Raithel, Vasileios Paschalidis,Comments:Subjects: astro-ph.HECreated: 2026-02-13; Updated: 2026-02-17; Datestamp: 2026-02-17
The fate of the remnant following the merger of two neutron stars initially on quasicircular orbits depends primarily on the mass of the initial neutron stars, the mass ratio, and the still-uncertain dense-matter equation of state (EoS). Previous works studying the threshold mass for prompt collapse to a BLACK HOLE have primarily focused on the uncertainties in the zero-temperature EoS, which are parametrized by a macroscopic quantity such as the characteristic neutron star radius. However, prompt collapse can take place either with or without a core bounce during the merger. In the bounce-collapse scenario, shocks can produce additional thermal support, potentially altering the threshold for collapse. In this work, we investigate the impact of the uncertainties in the finite-temperature part of the nuclear EoS on the threshold mass for prompt collapse in equal mass mergers. Using two cold EoSs, combined with four parametrizations of the finite-temperature part of the EoS, we find that the threshold mass is insensitive to realistic variations of the thermal prescription, at sub-percent accuracy. We report on the thermal properties and ejecta of mergers with masses just above the threshold mass, i.e., which experience a single core-bounce before collapsing. During the bounce, the thermal pressure can reach )(1-10)% of the cold pressure at supranuclear densities, depending on the thermal treatment, leading to modest differences in the dynamical ejecta that are launched and in the remnant disk mass as a result.
[abstract 39 / 57] (score: 2) - Title: New Insight from the James Webb Space Telescope on Variable Active Galactic NucleiAuthors: Bangzheng Sun, Haojing Yan, Wei Leong Tee, Feige Wang,Comments: Accepted for publication in ApJSubjects: astro-ph.GACreated: 2026-02-16; Updated: 2026-02-17; Datestamp: 2026-02-17
Variability detected in galaxies is usually attributed to their ACTIVE GALACTIC NUCLEi (AGNs). While all AGNs are intrinsically variable, the AGN unification model predicts that type~2 AGNs rarely vary because their engines are blocked by dust tori. Previous UV-to-near-IR variability studies largely support this expectation. Here, we present a variability study by James Webb Space Telescope (JWST) that reveals a more subtle picture. Using NIRCam imaging data from three surveys over $\sim$140~arcmin$^2$ in the COSMOS field, we found 117 galaxies with $\geq 4$$σ$ variability in the F356W band across $\sim$2-year baseline. Cross-matching with the existing JWST spectroscopic data, we identified five of them at $z=0.19$--3.69 (F356W corresponding to rest-frame $λ\approx0.76-2.97$~$μ$m), which were all coincidentally observed by a NIRSpec program almost contemporaneously with the last imaging epoch. One additional variable was identified at $z=0.90$ using the archival Keck telescope data. These six objects form our spectroscopic subsample. Interestingly, two reside in close-pair environments, while two others form a close pair themselves. Most of their light curves can hardly be explained by nuclear transients, and AGN variability is a more plausible cause. However, among these six objects, (1) only one shows broad Bracket and Pfund series permitted lines ($Δv > 1000$~km~s$^{-1}$) indicative of a type~1 AGN; (2) two show narrow permitted lines (H$α$ and/or He~I$\lambda10830$) consistent with type~2 AGNs, with another one likely type~2 based on the host galaxy properties; and (3) two others, which form a pair, show no emission lines. Our results add more challenges to the unification model.
[abstract 40 / 57] (score: 2) - Title: New analytical model of rotating BLACK HOLE with DARK MATTER halo: constraints from EHT observations and accretion diskAuthors: Uktamjon Uktamov, Sanjar Shaymatov, Bobomurat Ahmedov, Chengxun Yuan,Comments: 14 pages, 10 captioned figuresSubjects: gr-qcCreated: 2026-02-14; Updated: 2026-02-17; Datestamp: 2026-02-17
In this paper, we start from a static BLACK HOLE (BH) immersed in a Deanne-type DARK MATTER (DM) halo and employ the Newman-Janis algorithm (NJA) to generate the rotating BLACK HOLE solution with a DARK MATTER halo. Also, we have checked the validity of the obtained space-time. Then we study optical properties of newly obtained rotating BH in DM halo, including the shadow's geometrical shape, deflection angle of light based Ono, Ishihara and Asada (OID) method, photon sphere and the dependence of the shadow radius on DM parameters. Additionally, assuming that spacetime of a supermassive BLACK HOLE (SMBH) is described by the newly obtained rotating BH solution, we analyze the parameters of the model with shadow size estimates based on the Event Horizon Telescope (EHT) and Gravity collaboration observations of M87* and Sgr A* SMBHs. Then we have used Markov Chain Monte Carlo (MCMC) analysis to constrain DM parameters $ρ_s$, $r_s$ and BH mass M, BH spin a, also we show that best-fit values for the parameters $ρ_s$, $r_s$ are well agreement with previous results which indicate physically reasonability of the our model. Finally, we have analyzed the electroMAGNETic radiation flux of the rotating BH in the DM halo employing a ray tracing code.
[abstract 41 / 57] (score: 2) - Title: Reassessing the Spin of Second-born Black Holes in Coalescing Binary Black Holes and Its Connection to the chi_eff-q CorrelationAuthors: Zi-Yuan Wang, Ying Qin, Rui-Chong Hu, Yuan-Zhu Wang, Georges Meynet, Han-Feng Song,Comments: Accepted for publication in A&ASubjects: astro-ph.HE astro-ph.SR gr-qcCreated: 2026-02-14; Updated: 2026-02-17; Datestamp: 2026-02-17
The mass ratio q and effective inspiral spin chi_eff of binary BLACK HOLE (BBH) mergers in GWTC-4.0 show a weaker anti-correlation than in GWTC-3.0, motivating investigation of its physical origin. Within the isolated binary evolution framework, we adopt a recently proposed He-star wind prescription to study the spin of the second-born BH and its impact on the q-chi_eff relation. Using \texttt{MESA}, including the updated He-star wind, internal differential rotation, and tidal interactions, we examine how initial conditions and key processes determine the BH spin. We also perform rapid population synthesis with \texttt{COMPAS} to predict the population-level q-chi_eff correlation. The updated wind prescription is significantly weaker than the standard Dutch scheme, particularly at subsolar metallicity. Detailed binary models of He stars with BH companions show that the resulting BH spin is largely insensitive to the He star's evolutionary stage at the onset of tidal interaction and to the companion mass. Instead, wind mass loss dominates: more massive He-star progenitors produce lower-spinning BHs. Initial stellar rotation has only a minor effect, especially under strong tidal coupling. We provide a fitting formula for the spin of the second-born BH. Combining this formula with rapid population synthesis under default assumptions, we find that 85.8% of BBHs formed via stable mass transfer undergo mass-ratio reversal, compared to only 2.8% in the common-envelope channel. Notably, no correlation between q and chi_eff is found in either channel. Future work will explore alternative physical prescriptions and compare our predictions with BBH mergers reported by the LIGO-Virgo-KAGRA Collaboration.
[abstract 42 / 57] (score: 2) - Title: Gravitational-Wave Constraints on Neutron-Star Pressure Anisotropy via Universal RelationsAuthors: Victor Guedes, Siddarth Ajith, Shu Yan Lau, Kent Yagi,Comments: accepted in PRDSubjects: astro-ph.HE gr-qcCreated: 2026-02-16; Updated: 2026-02-17; Datestamp: 2026-02-17
Neutron stars may exhibit pressure anisotropy arising from various physical mechanisms, such as elasticity, MAGNETic fields, viscosity, and superfluidity. We compute the tidal deformability and the $f$-mode oscillation frequency of anisotropic neutron stars using a phenomenological quasi-local model characterized by a single dimensionless anisotropy parameter. We find that while the relation between the tidal deformability and the $f$-mode frequency depends on the degree of anisotropy, it remains largely insensitive to variations in the equation of state (the relation between radial pressure and energy density) for a fixed anisotropy parameter, similar to the isotropic case. Leveraging this anisotropy-dependent universal relation within a statistical framework, we place constraints on the anisotropy parameter using both the gravitational wave observation of GW170817 and simulated data for a GW170817-like event observed by a future network of detectors. We find that the anisotropy parameter can be constrained to order unity with current data, and the bounds remain comparable with future detector sensitivities. Importantly, these constraints are only weakly affected by uncertainties in the neutron-star equation of state.
[abstract 43 / 57] (score: 2) - Title: Probing AGN Feedback in Dwarf Galaxies with Spatially Resolved NIR Coronal Lines from JWSTAuthors: Archana Aravindan, Thomas Bohn, Gabriela Canalizo, Shobita Satyapal, Vivian U, Weizhe Liu, William Matzko, Sara Doan, Matthew Malkan, Lee Armus, Tohru Nagao, Tanio Diaz-Santos, Aditya Togi, Thomas S. Y. Lai, Sean T. Linden, Marina Bianchin, Yiqing Song, Loreto Barcos-Munoz, Aaron Evans, Hanae Inami, Kirsten Larson, Sabrina Stierwalt, Jason Surace,Comments: 22 pages, 14 figures, minor revisions, accepted for publication in ApJSubjects: astro-ph.GACreated: 2026-02-16; Updated: 2026-02-17; Datestamp: 2026-02-17
We present the first spatially resolved investigation of near-infrared coronal lines in dwarf galaxies hosting ACTIVE GALACTIC NUCLEi (AGN), using JWST/NIRSpec integral field spectroscopy. Coronal lines (CLs), which are forbidden transitions from highly ionized species with ionization potentials up to 450 eV, act as sensitive tracers of the AGN ionizing continuum and feedback processes. Across four dwarf galaxies with ionized gas outflows traced by the optical [O III] lines, we report the detection of 16 unique species of near-infrared CLs. Line ratio diagnostics indicate that photoionization from the AGN dominates the excitation of CLs. We find that the coronal line region in dwarf galaxies, traced by the various CLs, extends up to 0.5 kpc, and can constitute up to 10% of their host galaxy size. Correlations between CL luminosities and [O III] ionized gas outflow properties are consistent with a scenario in which AGN-driven outflows likely facilitate the detection of CLs and contribute to their extent. Several CLs, including [Si VI], [Si VII], and [Mg VIII], exhibit a secondary broad component with W$_{80}$ (the line width enclosing 80% of the total flux)> 300 km/s. If we interpret this spatially compact gas as part of an outflow, this would indicate that the outflowing gas includes a wide range of ionizations. The estimated energetics imply this highly ionized component is compact yet powerful enough to perturb gas in the central regions of the host dwarfs. These results indicate that AGN in low-mass galaxies may produce outflows capable of influencing their structure and evolution.
[abstract 44 / 57] (score: 2) - Title: Constraining Black Hole Parameters from Shadow and Inner-Shadow Morphology Considering Effects from Thick Disk Accretion FlowsAuthors: Julien A. Kearns, Dominic O. Chang, Daniel C. M. Palumbo, Shane W. Davis,Comments: 10 pages, 6 figuresSubjects: astro-ph.HECreated: 2026-02-14; Updated: 2026-02-17; Datestamp: 2026-02-17
We study the effects of emission geometry on the capability to constrain BLACK HOLE parameters from measurements of the shadow and inner-shadow of a Reissner-Nordström BLACK HOLE. We investigate the capability to constrain mass, charge, observer inclination, and emission co-latitude from images of BLACK HOLE accretion flows that would arise from thick and thin accretion disks. We confirm previous studies that have shown that independent radii measurements of the shadow and inner-shadow can constrain BLACK HOLE parameters if the viewing inclination is known, but find that it is only possible if the true emission geometry is also assumed. We study the constraining capabilities of the shadow and inner-shadow observations of M87* and Sgr A* like systems within the context of the BHEX and NgEHT future observatories.
[abstract 45 / 57] (score: 2) - Title: Searching for Neutron Star Mergers in the Absence of Gravitational Waves with Optical Afterglow EmissionAuthors: Haille M. L. Perkins, Gautham Narayan, Brian D. Fields, Ved G. Shah, Genevieve Schroeder,Comments: Submitted to ApJ; 19 pages, 9 figures, comments welcome!Subjects: astro-ph.HECreated: 2026-02-13; Updated: 2026-02-17; Datestamp: 2026-02-17
With the forth observing run of the LIGO-Virgo-KAGRA gravitational-wave network, which enabled the discovery of the kilonova (KN) counterpart to GW170817, ending with no new confirmed neutron star mergers, the intrinsic rate of these events must be even lower than previously estimated. As a result, building a sample of KNe will remain challenging even with continued GW observations, motivating complementary discovery strategies that do not rely on gravitational-wave triggers. In this work, we consider how leveraging bright short GAMMA-RAY BURST afterglows can aid in the discovery on KNe with the Rubin Observatory's upcoming Legacy Survey of Space and Time (LSST), whose unprecedented depth will make such detections feasible. We find that nearly on-axis ($θ_{\rm view} \leq 30°$) afterglows can enhance KN detection rates in the LSST $g$-band from $29^{+51}_{-21} \ \rm yr^{-1}$ to $91^{+160}_{-65} \ \rm yr^{-1}$. We further show how the colors of the observed events can be used to distinguish between neutron star merger counterparts with and without KN emission. This study demonstrates how critical multi-wavelength and multi-survey observations are for these rare events, especially without context from gravitational waves. Fortunately, detectable events will likely be discovered near peak with LSST, allowing for rapid follow-up and confirmation. We discuss key uncertainties in our study, particularly volume rate of merger events, and the degeneracy between the empirically determined explosion energy and ambient medium density.
[abstract 46 / 57] (score: 2) - Title: New Dynamical Measurements from a Lensed Quasar Sample: Joint Analysis Constrains the Mass Profile Evolution of Lens GalaxiesAuthors: Ziyu Guo, Yun Chen, Yiping Shu, Jiaze Gao, Hui Li, Zizhao He, Jun Wang,Comments: 13 pages, 5 figuresSubjects: astro-ph.GACreated: 2026-02-14; Updated: 2026-02-17; Datestamp: 2026-02-17
We present a systematic study of the internal mass structure of early-type galaxies (ETGs) based on 106 galaxy-scale strong gravitational lenses with background QUASARs, all having spectroscopic redshifts. From this parent sample, we select 24 systems with high-quality ancillary data for joint analysis of strong lensing geometry and stellar kinematics. A key contribution is the derivation of new single-aperture stellar velocity dispersions for 11 lens galaxies via an iterative spectroscopic fitting procedure that mitigates QUASAR contamination, providing previously unavailable data. We model the total mass-density profile as a power law, $ρ\propto r^{-γ}$, and parameterise its logarithmic slope as $γ= γ_0 + γ_z \cdot z_l + γ_s \cdot \log \tildeΣ$, where $z_l$ is the lens redshift and $\tildeΣ$ the surface mass density. Within a flat $Λ$CDM framework and using DESI BAO measurements as a prior, we constrain the parameters via Monte Carlo nested sampling to $γ_0 = 1.62^{+0.11}_{-0.12}$, $γ_z = -0.35^{+0.08}_{-0.09}$, and $γ_s = 0.37^{+0.08}_{-0.07}$ ($68\%$ confidence intervals). Our results robustly demonstrate that $γ$ increases with surface mass density ($γ_s > 0$) and decreases with redshift ($γ_z < 0$). This implies that, at fixed redshift, galaxies with denser stellar cores have steeper mass profiles, while at fixed density, profiles become shallower at higher redshifts. By successfully applying the joint lensing--dynamics method to a substantial, independently acquired sample of lensed QUASARs, this work provides crucial validation of structural trends previously observed in galaxy--galaxy lensing systems, reinforcing the established evolutionary picture for massive ETGs and establishing lensed QUASARs as a potent probe of galaxy structure.
[abstract 47 / 57] (score: 2) - Title: Dynamical Preconditions for Ice Formation in Supernova Remnant and Cloud Interactions: A 2D MHD StudyAuthors: A. Yeghikyan, M. Rah, S. Shamyar, S. Khachatryan,Comments: 11 pages, 5 figures. Published in Communications of the Byurakan Astrophysical Observatory (CoBAO), Vol. 72, Issue 2Subjects: astro-ph.HECreated: 2026-02-14; Updated: 2026-02-17; Datestamp: 2026-02-17
Water ice has been detected in several SUPERNOVA remnants despite the strong heating and radiation in these environments. This challenges standard expectations for dust survival. Using two dimensional MAGNETohydrodynamic simulations, we study how a SUPERNOVA shock interacts with a dense interstellar cloud. The simulations show that the shock naturally compresses the cloud into dense structures similar to those inferred in well known remnants. Although temperatures remain high in the adiabatic phase, simple considerations indicate that cooling would act quickly once included. These results suggest that shock cloud interactions create the physical conditions needed for water ice to form. Future work including radiative cooling and grain surface chemistry will allow direct modelling of ice growth in these compressed regions.
[abstract 48 / 57] (score: 2) - Title: Estimatingthe Contribution of Galactic Neutrino SourcesAuthors: Mohadeseh Ozlati Moghadam, Kathrin Egberts, Rowan Batzofin, Constantin Steppa, Elisa Bernardini,Comments: This paper has been submitted and accepted by Astroparticle jounralSubjects: astro-ph.HECreated: 2026-02-14; Updated: 2026-02-17; Datestamp: 2026-02-17
The Milky Way hosts astrophysical accelerators capable of producing high-energy COSMIC RAYs. These COSMIC RAYs can interact with the interstellar medium (ISM) across the Galaxy to produce neutrinos and gamma rays (propagation component), while their interactions with ambient material at their acceleration sites, such as SUPERNOVA remnants, can give rise to the source component of the gamma-ray and neutrino flux. In this paper, we estimate the source component of the Galactic neutrino flux using simulated populations of Galactic gamma-ray sources. We compare our results with observations from neutrino experiments in the energy range of 1-30 TeV. Using simulated populations of Galactic TeV gamma-ray sources, we exploit the correlation between gamma rays and neutrinos and introduce a bracketing approach to constrain the range for the source contribution of the Galactic neutrino flux. For the upper limit, we used a simulation describing the entity of Galactic gamma-ray sources, whereas the lower limit was estimated using the hadronic component of the Galactic SUPERNOVA remnant population. Our results show that the difference between this maximum and minimum is less than an order of magnitude and the flux range is comparable to the Galactic neutrino flux from the cosmic-ray interaction with the ISM. The results agree with the observed signals from IceCube and ANTARES and suggest that the propagation component, combined with the minimum source contribution predicted by the SUPERNOVA-remnant model, approaches the observed neutrino flux, leaving little room for significant enhancements of the emission originating from propagating COSMIC RAYs.
[abstract 49 / 57] (score: 2) - Title: J-PAS: Semi-Supervised Sim-to-Obs Transfer for Robust Star--Galaxy--Quasar ClassificationAuthors: Daniel López-Cano, L. Raul Abramo, L. Nakazono, I. Pérez-Ràfols, G. Martínez-Solaeche, J. Chaves-Montero, Matthew M. Pieri, Jailson Alcaniz, Narciso Benitez, Silvia Bonoli, Saulo Carneiro, Javier Cenarro, David Cristóbal-Hornillos, Simone Daflon, Renato Dupke, Alessandro Ederoclite, Rosa González Delgado, Antonio Hernán-Caballero, Carlos Hernández-Monteagudo, Jifeng Liu, Carlos López-Sanjuan, Antonio Marín-Franch, Claudia Mendes de Oliveira, Mariano Moles, Fernando Roig, Laerte Sodré, Keith Taylor, Jesús Varela, Héctor Vázquez Ramió, Jose Vilchez, Javier Zaragoza-Cardiel,Comments: 18 pages, 7 figures. To be submitted to ApJSubjects: astro-ph.IM astro-ph.COCreated: 2026-02-14; Updated: 2026-02-17; Datestamp: 2026-02-17
Modern studies in astrophysics and cosmology increasingly rely on simulations and cross-survey analyses, yet differences in data generation, instrumentation, calibration, and unmodeled physics introduce distribution mismatches between datasets (``domain shift''). In machine-learning pipelines, this occurs when the joint distribution of inputs and labels differs between the training (source) and application (target) domains, causing source-trained models to underperform on the target. Transfer learning and domain adaptation provide principled ways to mitigate this effect. We study a concrete simulation-to-observation case: semi-supervised domain adaptation (SSDA) to transfer a four-class spectral classifier -- high-redshift QUASARs, low-redshift QUASARs, galaxies, and stars -- from J-PAS mock catalogs based on DESI spectra to real J-PAS observations. Our pipeline pretrains on abundant labeled DESI$\rightarrow$J-PAS mocks and adapts to the target domain using a small labeled J-PAS subset. We benchmark SSDA against two baselines: a J-PAS--only supervised model trained with the same target-label budget, and a mocks-only model evaluated on held-out J-PAS data. On this held-out J-PAS data, SSDA achieves a macro-F1 score (balancing precision and recall) of $0.82$ and an overall true positive rate of $0.89$, compared to $0.79/0.85$ for the J-PAS--only baseline and $0.73/0.87$ for the mocks-only model. The gains are driven primarily by improved QUASAR classification, especially in the high-redshift subclass ($\mathrm{F1}=0.66$ vs.\ $0.55/0.37$), yielding better-calibrated candidate lists for spectroscopic targeting (e.g., WEAVE-QSO) and AGN searches. This study shows how modest target supervision enables robust, data-efficient simulation-to-observation transfer when simulations are plentiful but target labels are scarce.
[abstract 50 / 57] (score: 2) - Title: Three-dimensional kink modes in solar coronal slabs: group velocities and their implications for impulsively excited wavesAuthors: Jing Liu, Bo Li, Mijie Shi, Mingzhe Guo, Hui Yu,Comments: 14 pages, 8 figures, accepted for publication in A&ASubjects: astro-ph.SRCreated: 2026-02-15; Updated: 2026-02-17; Datestamp: 2026-02-17
Little attention has been paid to group velocities of three-dimensional (3D) MHD waves in solar coronal seismology. This study aims to present a rather comprehensive examination on the group velocities of trapped 3D kink modes in coronal slabs, emphasizing the connection of mode analysis to both mode characterization and impulsively excited 3D kink waves. We work in linear, ideal, pressureless MHD, and take the equilibrium slab to be symmetrically structured only in one transverse direction. The dispersion relation is numerically solved, with the results understood by making in-depth analytical progress. We address both the transverse fundamental and its first overtone. We develop a three-subgroup scheme for categorizing 3D kink modes on the plane spanned by the axial and out-of-plane wavenumbers. The group ($\vec{v}_{\rm gr}$) and phase velocities ($\vec{v}_{\rm ph}$) sit on the same side of the equilibrium MAGNETic field ($\vec{B}_0$) for the ``$\vec{B}_0$-same-side A'' and ``$\vec{B}_0$-same-side F'' subgroups, which are further discriminated by the directional similarity of $\vec{v}_{\rm gr}$ and $\vec{B}_0$. The ``$\vec{B}_0$-straddling'' subgroup is peculiar in that $\vec{v}_{\rm gr}$ and $\vec{v}_{\rm ph}$ lie astride $\vec{B}_0$, a feature that cannot be found for waves in unbounded uniform media in pressureless MHD. This ``$\vec{B}_0$-straddling'' subgroup pertains to both the fundamental and its overtones. We further place our results in the context of impulsive waves, employing the method of stationary phase to predict the large-time wavefront morphology in the plane of symmetry of the equilibrium slab. Wavefronts directed toward $\vec{B}_0$ derive exclusively from ``$\vec{B}_0$-straddling'' modes, and are confined to narrow sectors.
[abstract 51 / 57] (score: 2) - Title: Circular orbits and observational features of the rotating Simpson-Visser BLACK HOLE surrounded by a thin accretion diskAuthors: Ziyang Li, Shou-Qi Liu, Jia-Hui Huang,Comments: 18 pages, many figuresSubjects: astro-ph.HE gr-qcCreated: 2026-02-16; Updated: 2026-02-17; Datestamp: 2026-02-17
We present a systematic investigation of the radiative properties and optical appearance of rotating SV BLACK HOLEs surrounded by a thin accretion disks, and mainly analyze the influence of the regularization parameter $g$ on related observables. The results show that although the kinetic quantities and the location of the innermost stable circular orbit (ISCO) depend on the regularization parameter $g$, the radiative efficiency of the rotating SV BLACK HOLE is the same as its Kerr counterpart. Within the Novikov-Thorne thin-disk model, the radiative flux, effective temperature, and spectral luminosity are studied, and by adopting observational parameters relevant to SgrA* and M87*, concrete examples of the rotating SV BLACK HOLEs are calculated and compared with that of the Kerr BLACK HOLEs. The results show that the parameter $g$ suppresses the maximum values of these quantities. In addition, using a backward ray-tracing technique, we numerically simulate the optical appearance of rotating SV BLACK HOLEs and analyze the corresponding intensity images, redshift and observed flux distributions. Our results show that these quantities are affected by $g$. In particular, as $g$ increases, the observed intensity is significantly suppressed and the photon ring region has remarkable increase in its width. Our findings suggest that accretion-disk-related observables may provide important avenues to distinguish rotating SV BLACK HOLEs and Kerr BLACK HOLEs, and offer theoretical guidance for future high-resolution observations.
[abstract 52 / 57] (score: 2) - Title: Wavemaker and endogeneity of gravitationally stretched weakly viscoelastic JETsAuthors: Daniel Moreno-Boza,Comments:Subjects: physics.flu-dynCreated: 2026-02-16; Updated: 2026-02-17; Datestamp: 2026-02-17
Highly stretched capillary JETs produced by gravity are central to drop generation, micro-thread formation, and extensional-rheometry concepts. For Newtonian fluids, the transition from steady JETting to self-excited oscillations in a gravitationally stretched JET is predicted accurately by one-dimensional slender-JET equations that retain the exact interfacial curvature and admit a global eigenvalue analysis Rubio-Rubio et al. 2013. Separately, weakly viscoelastic JETs governed by Oldroyd--B/Giesekus constitutive laws exhibit elastocapillary regimes and beads-on-a-string dynamics that are well captured by one-dimensional free-surface models Ardekani et al. 2010. Here we formulate a unified one-dimensional model for gravitationally stretched viscoelastic JETs, combining full-curvature capillarity with a Giesekus stress closure, and we analyse its global linear stability on spatially developing base states. We first benchmark the Newtonian limit, reproducing marginal spectra and base-flow profiles, and then quantify how elasticity shifts the critical JETting--dripping boundary by tracking the leading global Hopf eigenpair across the rheological parametric space. For experimentally relevant moderate elasticity, characterised by order-unity Deborah numbers, polymeric tension modifies both the critical Weber number and the selected oscillation frequency, and endogeneity decompositions reveal that marginality results from a balance between capillary/kinematic contributions and an additional elastic-stress feedback pathway. To interpret and predict the onset mechanism, we compute wavemakers and receptivity/structural-sensitivity fields from direct--adjoint eigenfunctions, showing that viscoelasticity broadens the sensitivity region downstream while the adjoint remains strongly localized near the inlet, thereby identifying the near-nozzle region as the dominant receptive location.
[abstract 53 / 57] (score: 2) - Title: Recursive regularised lattice Boltzmann method for MAGNETohydrodynamicsAuthors: Alessandro De Rosis,Comments:Subjects: physics.flu-dyn physics.comp-phCreated: 2026-02-16; Updated: 2026-02-17; Datestamp: 2026-02-17
We present and test a recursive regularised lattice Boltzmann method for incompressible MAGNETohydrodynamic (MHD) flows. The approach is based on a double-distribution formulation, in which the MAGNETic field is evolved using a standard BGK lattice Boltzmann scheme, while the fluid solver is enhanced through a Hermite-based recursive regularisation of the non-equilibrium moments. The method exploits a fourth-order Hermite expansion of the equilibrium distribution on the D2Q9 lattice, allowing higher-order isotropy to be retained while selectively filtering spurious non-hydrodynamic contributions. The regularisation procedure reconstructs the non-equilibrium distribution from physically consistent Hermite coefficients, avoiding explicit evaluation of velocity gradients. The resulting scheme preserves the correct incompressible MHD limit, improves numerical stability at low viscosities, and reduces lattice-dependent artefacts. The proposed formulation provides a robust and versatile framework for MHD simulations and offers a systematic route for extending regularised lattice Boltzmann methods to coupled multiphysics systems.
[abstract 54 / 57] (score: 2) - Title: Bounds on Lorentz invariance violation from muon fluctuations at the Pierre Auger ObservatoryAuthors: The Pierre Auger Collaboration, A. Abdul Halim, P. Abreu, M. Aglietta, I. Allekotte, K. Almeida Cheminant, R. Aloisio, J. Alvarez-Muñiz, A. Ambrosone, J. Ammerman Yebra, L. Anchordoqui, B. Andrada, L. Andrade Dourado, L. Apollonio, C. Aramo, E. Arnone, J. C. Arteaga Velázquez, P. Assis, G. Avila, E. Avocone, A. Bakalova, Y. Balibrea, A. Baluta, F. Barbato, A. Bartz Mocellin, J. P. Behler, C. Berat, M. E. Bertaina, M. Bianciotto, P. L. Biermann, V. Binet, K. Bismark, T. Bister, J. Biteau, J. Blazek, J. Blümer, M. Boháčová, D. Boncioli, C. Bonifazi, N. Borodai, J. Brack, P. G. Brichetto Orquera, A. Bueno, S. Buitink, M. Büsken, A. Bwembya, K. S. Caballero-Mora, S. Cabana-Freire, L. Caccianiga, J. Caraça-Valente, R. Caruso, A. Castellina, F. Catalani, G. Cataldi, L. Cazon, M. Cerda, B. Čermáková, A. Cermenati, K. Cerny, J. A. Chinellato, J. Chudoba, L. Chytka, R. W. Clay, A. C. Cobos Cerutti, R. Colalillo, R. Conceição, G. Consolati, M. Conte, F. Convenga, D. Correia dos Santos, P. J. Costa, C. E. Covault, M. Cristinziani, C. S. Cruz Sanchez, S. Dasso, K. Daumiller, B. R. Dawson, R. M. de Almeida, E. -T. de Boone, B. de Errico, J. de Jesús, S. J. de Jong, J. R. T. de Mello Neto, I. De Mitri, D. de Oliveira Franco, F. de Palma, V. de Souza, E. De Vito, A. Del Popolo, O. Deligny, N. Denner, K. Denner Syrokvas, L. Deval, A. di Matteo, C. Dobrigkeit, J. C. D'Olivo, L. M. Domingues Mendes, Y. Dominguez Ballesteros, Q. Dorosti, R. C. dos Anjos, J. Ebr, F. Ellwanger, R. Engel, I. Epicoco, M. Erdmann, A. Etchegoyen, C. Evoli, H. Falcke, G. Farrar, A. C. Fauth, T. Fehler, F. Feldbusch, A. Fernandes, M. Fernández Alonso, B. Fick, J. M. Figueira, P. Filip, A. Filipčič, T. Fitoussi, B. Flaggs, A. Franco, M. Freitas, T. Fujii, A. Fuster, C. Galea, B. García, C. Gaudu, P. L. Ghia, U. Giaccari, M. Giammarco, C. Glaser, F. Gobbi, F. Gollan, G. Golup, P. F. Gómez Vitale, J. P. Gongora, J. M. González, N. González, D. Góra, A. Gorgi, M. Gottowik, F. Guarino, G. P. Guedes, Y. C. Guerra, L. Gülzow, S. Hahn, P. Hamal, M. R. Hampel, P. Hansen, V. M. Harvey, A. Haungs, M. Havelka, T. Hebbeker, C. Hojvat, J. R. Hörandel, P. Horvath, M. Hrabovský, T. Huege, A. Insolia, P. G. Isar, M. Ismaiel, P. Janecek, V. Jilek, K. -H. Kampert, B. Keilhauer, A. Khakurdikar, V. V. Kizakke Covilakam, H. O. Klages, M. Kleifges, J. Köhler, F. Krieger, M. Kubatova, N. Kunka, B. L. Lago, N. Langner, N. Leal, M. A. Leigui de Oliveira, Y. Lema-Capeans, A. Letessier-Selvon, I. Lhenry-Yvon, L. Lopes, J. P. Lundquist, M. Mallamaci, S. Mancuso, D. Mandat, P. Mantsch, A. G. Mariazzi, C. Marinelli, I. C. Mariş, G. Marsella, D. Martello, S. Martinelli, O. Martínez Bravo, M. A. Martins, H. -J. Mathes, J. Matthews, G. Matthiae, E. Mayotte, S. Mayotte, P. O. Mazur, G. Medina-Tanco, J. Meinert, D. Melo, A. Menshikov, C. Merx, S. Michal, M. I. Micheletti, L. Miramonti, M. Mogarkar, S. Mollerach, F. Montanet, L. Morejon, K. Mulrey, R. Mussa, W. M. Namasaka, S. Negi, L. Nellen, K. Nguyen, G. Nicora, M. Niechciol, D. Nitz, D. Nosek, A. Novikov, V. Novotny, L. Nožka, A. Nucita, L. A. Núñez, S. E. Nuza, J. Ochoa, M. Olegario, C. Oliveira, L. Östman, M. Palatka, J. Pallotta, S. Panja, G. Parente, T. Paulsen, J. Pawlowsky, M. Pech, J. Pękala, R. Pelayo, V. Pelgrims, C. Pérez Bertolli, L. Perrone, S. Petrera, C. Petrucci, T. Pierog, M. Pimenta, M. Platino, B. Pont, M. Pourmohammad Shahvar, P. Privitera, C. Priyadarshi, M. Prouza, K. Pytel, S. Querchfeld, J. Rautenberg, D. Ravignani, J. V. Reginatto Akim, A. Reuzki, J. Ridky, F. Riehn, M. Risse, V. Rizi, E. Rodriguez, G. Rodriguez Fernandez, J. Rodriguez Rojo, S. Rossoni, M. Roth, E. Roulet, A. C. Rovero, A. Saftoiu, M. Saharan, F. Salamida, H. Salazar, G. Salina, P. Sampathkumar, N. San Martin, J. D. Sanabria Gomez, F. Sánchez, F. M. Sánchez Rodriguez, E. Santos, F. Sarazin, R. Sarmento, R. Sato, P. Savina, V. Scherini, H. Schieler, M. Schimp, D. Schmidt, O. Scholten, H. Schoorlemmer, P. Schovánek, F. G. Schröder, J. Schulte, T. Schulz, S. J. Sciutto, M. Scornavacche, A. Sedoski, S. Sehgal, S. U. Shivashankara, G. Sigl, K. Simkova, F. Simon, R. Šmída, S. Soares Sippert, P. Sommers, M. Stadelmaier, S. Stanič, J. Stasielak, P. Stassi, S. Strähnz, M. Straub, T. Suomijärvi, A. D. Supanitsky, Z. Svozilikova, Z. Szadkowski, F. Tairli, M. Tambone, A. Tapia, C. Taricco, C. Timmermans, O. Tkachenko, P. Tobiska, C. J. Todero Peixoto, B. Tomé, A. Travaini, P. Travnicek, C. Trimarelli, M. Tueros, M. Unger, R. Uzeiroska, L. Vaclavek, M. Vacula, I. Vaiman, J. F. Valdés Galicia, L. Valore, P. van Dillen, E. Varela, V. Vašíčková, A. Vásquez-Ramírez, D. Veberič, I. D. Vergara Quispe, S. Verpoest, V. Verzi, J. Vicha, S. Vorobiov, J. B. Vuta, C. Watanabe, A. A. Watson, A. Weindl, M. Weitz, L. Wiencke, H. Wilczyński, B. Wundheiler, B. Yue, A. Yushkov, E. Zas, D. Zavrtanik, M. Zavrtanik,Comments: 15 pages, 9 figuresSubjects: astro-ph.HE gr-qc hep-phCreated: 2026-02-16; Updated: 2026-02-17; Datestamp: 2026-02-17
Quantum gravity theories often modify spacetime symmetries. In particular, Lorentz invariance may be violated when approaching the Planck scale. Although the scales at which interactions occur in extensive air showers induced by ultra-high-energy COSMIC RAYs in the atmosphere are many orders of magnitude below the Planck scale, these violations might still be observable. In this work, the fluctuations in the number of muons in the extensive air showers measured at the Pierre Auger Observatory are exploited, for the first time, to constrain Lorentz invariance violations. The bounds derived in the hadronic sector are the strongest ever obtained, and do not rely on assumptions about the mass composition of ultra-high-energy COSMIC RAYs. The fluctuations in the number of muons constitute a new and powerful observable to further explore Lorentz invariance in a region of the parameter space not accessible to other observables.
[abstract 55 / 57] (score: 2) - Title: The impact of the formation channel on gravitational-wave-galaxy cross-correlationsAuthors: Kabir Chakravarti, Federico R. Urban,Comments:Subjects: astro-ph.COCreated: 2026-02-16; Updated: 2026-02-17; Datestamp: 2026-02-17
The angular, harmonic cross-correlation between gravitational wave (GW) events and galaxy catalogues contains rich information on the large-scale structure and the origin of compact binary mergers. In this work, we study how uncertainties in the binary formation channel affect the predicted cross-correlation signal for both current-generation and next-generation networks of detectors. We generate five mock GW catalogues for which we vary the progenitor-to-remnant mass-transfer function and the time-delay probability distribution between progenitor and remnant. We then cross-correlate these catalogues with galaxy samples modelled on the 2MASS Photometric Redshift catalogue (2MPZ) and the Gaia-unWISE QUASAR catalogue (Quaia). We find that the mass-transfer function has negligible effect on the cross-correlation signal, with differences remaining within redshift uncertainties. In contrast, the time-delay distribution dramatically affects the redshift distribution of the GW events and, with it, the cross-correlation signal, particularly for shallow galaxy catalogues. In particular, current-generation facilities can achieve significant detections only for the longest time delays when cross-correlated with 2MPZ, whilst all cross-correlations with the deeper Quaia catalogue are marginally detectable or consistent with zero. Our exploratory results thus demonstrate that forecasts on cosmological or astrophysical parameters derived from GW-galaxy cross-correlations are, as expected, strongly sensitive to the assumed binary formation history.
[abstract 56 / 57] (score: 2) - Title: Tarnished by Tools: Cost of Systematics in Golden Dark Siren CosmologyAuthors: Giovanni Benetti, Koustav Chandra, Bangalore S. Sathyaprakash,Comments: 19 pages, 8 figuresSubjects: gr-qcCreated: 2026-02-16; Updated: 2026-02-17; Datestamp: 2026-02-17
Golden dark sirens - exceptionally well-localized gravitational-wave (GW) sources without electroMAGNETic counterparts - offer a powerful route to precision measurements of the Hubble constant, $H_0$, with next-generation (XG) detectors. The statistical promise of this method, however, places stringent demands on waveform accuracy and detector calibration, as even small systematic errors can dominate over statistical uncertainties at high signal-to-noise ratios. We investigate the impact of waveform-modeling systematics on golden dark siren cosmology using a synthetic population of binary BLACK HOLEs consistent with current GW observations and analyzed in the XG-detector era. By comparing state-of-the-art waveform models against numerical-relativity-based reference signals, we quantify modeling inaccuracies from both modeling and data-analysis perspectives and assess how they propagate into biases in luminosity distance, host-galaxy association, and single-event $H_0$ inference. We find that while current waveform models often allow recovery of statistically consistent $H_0$ posteriors, small waveform-induced biases can significantly affect three-dimensional localization and host galaxy ranking, occasionally leading to incorrect redshift assignments. We further derive order-of-magnitude requirements on detector calibration accuracy needed to ensure that calibration systematics remain subdominant for golden dark sirens observed with XG networks. To realize sub-percent $H_0$ measurements with golden dark sirens will require waveform and calibration accuracies that scale as $\mathcal{O}(ρ^{-2})$ with signal-to-noise ratio, motivating sustained advances in waveform modeling, numerical relativity, and detector calibration for the XG era.
[abstract 57 / 57] (score: 2) - Title: Modeling isolated MAGNETar spin-down evolution and implications for long-period radio transientsAuthors: Jon Kwong, Kaya Mori,Comments:Subjects: astro-ph.HECreated: 2026-02-16; Updated: 2026-02-17; Datestamp: 2026-02-17
Long-period radio transients (LPTs) are a new class of radio sources characterized by long spin periods ($P_{\text{spin}}>10^3$ s) and highly variable radio emission. While known MAGNETars are relatively young ($τ<10^5$ yrs) with spin periods clustered between $1-10$ sec, it has been proposed that LPTs may be linked to a missing population of older MAGNETars. In this paper, we present an extensive parametric analysis of isolated MAGNETar spin evolution using various propeller spin-down models. In general, at higher initial MAGNETar B-fields ($B_0>\sim10^{15}$ G) and larger ambient densities ($n_0>\sim10^2$ cm$^{-3}$), MAGNETars will transition to the propeller phase earlier, and they start accreting gas from the ISM or molecular clouds after $τ\sim10^8$ yrs. We found that a transition from the pulsar to the propeller phase is required to reach the observed LPT period range of $P>10^3$ s. More specifically, our population synthesis study based on Monte-Carlo simulations shows that two propeller models can account for most of the observed LPT periods ($P\sim1-400$ [min]) and their period derivative constraints ($\dot{P}<10^{-9}$ s s$^{-1}$). Our spin-down models predict that (1) nearby radio-quiet neutron stars with the estimated dipole $B$-field range of $B\sim(1-5)\times10^{13}$ G will transition to the propeller phase eventually after $τ>\sim10^7$ yrs; (2) thermal X-ray emission from accretion-phase MAGNETars becomes too faint for detection after traveling ($d>\sim10$ kpc) from their birth places; (3) sporadic radio outbursts observed from LPTs may not be explained by regular radio pulsar and MAGNETar emission mechanisms that operate during the propeller phase.
arXiv:2602.13411 [pdf, ps, other]
arXiv:2602.13391 [pdf, ps, other]
arXiv:2602.14640 [pdf, ps, other]
arXiv:2602.14300 [pdf, ps, other]
arXiv:2602.14838 [pdf, ps, other]
arXiv:2410.10579 [pdf, ps, other]
arXiv:2505.01708 [pdf, ps, other]
arXiv:2506.11333 [pdf, ps, other]
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