Journal of High Energy Astrophysics最新文献

{"title":"High mass pulsars as hybrid stars: Phase transitions and oscillation modes","authors":"Soumen Podder ,&nbsp;Sujan Kumar Roy ,&nbsp;Suman Pal ,&nbsp;Gargi Chaudhuri","doi":"10.1016/j.jheap.2025.100457","DOIUrl":"10.1016/j.jheap.2025.100457","url":null,"abstract":"<div><div>Recent observations of high-mass pulsars justify the investigation of the internal composition of neutron stars. At the extreme densities relevant to such objects, quantum chromodynamics predicts a phase transition in neutron star matter to deconfined quark matter. However, the nature of this phase transition remains uncertain due to the absence of direct observational evidence. In this work, we investigate the possibility of such a transition inside neutron stars, focusing on the scenario of a first-order phase transition. In particular, we consider the slow conversion of the hadronic phase into the deconfined quark phase. For comparison, we also construct hybrid stars using a continuous Gibbs phase transition description. Our findings indicate that the neutron star structure is significantly influenced by the adopted phase transition model. In the context of gravitational wave observations, we analyze the non-radial f-mode oscillations in high-mass pulsars. We find that these oscillations are sensitive to both the nature of the phase transition and the underlying neutron star structure. Consequently, we explore neutron star oscillations as a potential probe of the internal composition of high-mass pulsars, as these oscillation modes can provide signatures of phase transitions.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"49 ","pages":"Article 100457"},"PeriodicalIF":10.5,"publicationDate":"2025-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145049370","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Reconciling fractional power potential and EGB gravity in the light of ACT","authors":"Mehnaz Zahoor ,&nbsp;Suhail Khan ,&nbsp;Imtiyaz Ahmad Bhat","doi":"10.1016/j.jheap.2025.100458","DOIUrl":"10.1016/j.jheap.2025.100458","url":null,"abstract":"<div><div>Recent results from the ACT collaboration indicate a higher value for the scalar spectral index, with <span><math><msub><mrow><mi>n</mi></mrow><mrow><mi>s</mi></mrow></msub><mo>=</mo><mn>0.9743</mn><mo>±</mo><mn>0.0034</mn></math></span>, which sets tighter constraints on inflationary models, and these shifts are not in favor of many pre-existing scenarios, including the widely studied and accepted standard Starobinsky model. In this paper, we examine the fractional power scalar potential within the framework of Einstein–Gauss–Bonnet (EGB) gravity, incorporating the standard slow-roll approximation. The EGB theory, motivated by higher-dimensional models, introduces quadratic curvature corrections and a coupling between the scalar field and the Gauss–Bonnet term, thereby modifying the cosmological dynamics. The results show good agreement with observational data, placing the predictions within the 1<em>σ</em> region of the ACT <em>r</em>–<span><math><msub><mrow><mi>n</mi></mrow><mrow><mi>s</mi></mrow></msub></math></span> constraint plot. Furthermore, incorporating the running of the scalar spectral index reinforces the model's consistency with observational bounds. We also explore the parameter space of the EGB couplings and identify the range of free parameters for which the results of <span><math><msub><mrow><mi>n</mi></mrow><mrow><mi>s</mi></mrow></msub></math></span> and <em>r</em> values remain within the 1<em>σ</em> region of the ACT constraints. Finally, we also investigate the reheating phase, demonstrating that the model not only agrees with ACT data but also satisfies the lower bound on the reheating temperature, thereby ensuring a consistent and viable cosmological scenario.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"49 ","pages":"Article 100458"},"PeriodicalIF":10.5,"publicationDate":"2025-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145048716","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The effective running Hubble constant in SNe Ia as a marker for the dark energy nature","authors":"E. Fazzari ,&nbsp;M.G. Dainotti ,&nbsp;G. Montani ,&nbsp;A. Melchiorri","doi":"10.1016/j.jheap.2025.100459","DOIUrl":"10.1016/j.jheap.2025.100459","url":null,"abstract":"<div><div>We propose a new method that reveal the nature of dark energy (DE) evolution. Specifically, the method consists of studying the evolving trend regarding the effective running Hubble constant: when it increases, it indicates a quintessence nature, and when it decreases, it reveals a phantom behavior.</div><div>Within the framework of the dark energy models we analyze three parameterizations: the <em>w</em>CDM model, a reduced Chevallier-Polarski-Linder (CPL) model and a new theoretical model based on the possible creation of dark energy by the time-varying gravitational field of the expanding Universe.</div><div>For each DE model, we construct a theoretical effective running Hubble constant, i.e. a function of the redshift, which highlights the difference between modified dynamics and the ΛCDM-one. Furthermore, these dark energy models are compared to a phenomenological model, called the power-law model (PL), that assumes a decreasing trend of the Hubble constant with redshift, and to the ΛCDM one. These three theoretical functions for DE are fitted against the binned Type Ia Supernovae (SNe Ia) data samples, i.e. the Pantheon and the Master samples, the latter being a collection of SNe Ia from 4 catalogs: Dark Energy Survey (DES), PantheonPlus, Pantheon and Joint Lightcurve Analysis (JLA), without duplicated SNe Ia, called the Master sample.</div><div>The main result of our study is that the phenomenological PL model is statistically favored compared to the other proposed scenarios, both for the Pantheon and the Master samples. At this stage, the SNe Ia data do not indicate that the evolution of dark energy models among the studied ones is favored respect to the ΛCDM. Nevertheless, the binned Pantheon sample allows for a discrimination of the nature of dark energy at least at the <span><math><mn>1</mn><mspace></mspace><mi>σ</mi></math></span> level via the fit of the effective running Hubble constant.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"49 ","pages":"Article 100459"},"PeriodicalIF":10.5,"publicationDate":"2025-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145049369","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A set of distinctive properties ruling the prompt emission of GRB 230307A and other long γ-ray bursts from compact object mergers","authors":"R. Maccary ,&nbsp;C. Guidorzi ,&nbsp;M. Maistrello ,&nbsp;S. Kobayashi ,&nbsp;M. Bulla ,&nbsp;R. Moradi ,&nbsp;S.-X. Yi ,&nbsp;C.W. Wang ,&nbsp;W.L. Zhang ,&nbsp;W.-J. Tan ,&nbsp;S.-L. Xiong ,&nbsp;S.-N. Zhang","doi":"10.1016/j.jheap.2025.100456","DOIUrl":"10.1016/j.jheap.2025.100456","url":null,"abstract":"<div><div>Short gamma-ray bursts (SGRBs), occasionally followed by a long and spectrally soft extended emission, are associated with compact object mergers (COMs). Yet, a few recent long GRBs (LGRBs) show compelling evidence for a COM origin, in contrast with the massive-star core-collapse origin of most LGRBs. While possible COM indicators were found, such as the minimum variability timescale (MVT), a detailed and unique characterisation of their <em>γ</em>-ray prompt emission that may help identify and explain their deceptively long profile is yet to be found. Here we report the discovery of a set of distinctive properties that rule the temporal and spectral evolution of GRB 230307A, a LGRB with evidence for a COM origin. Specifically, the sequence of pulses that make up its profile is characterised by an exponential evolution of (i) flux intensities, (ii) waiting times between adjacent pulses, (iii) pulse durations, and (iv) spectral peak energy. Analogous patterns are observed in the prompt emission of other long COM candidates. The observed evolution of gamma-ray pulses would imply that a relativistic jet is colliding with more slowly expanding material. This contrasts with the standard internal shock model for typical LGRBs, in which dissipation occurs at random locations within the jet itself. We tentatively propose a few simple toy models that may explain these properties and are able to reproduce the overall time profile.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"49 ","pages":"Article 100456"},"PeriodicalIF":10.5,"publicationDate":"2025-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144988064","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Broadband spectral modeling of blazars: Constraining the Lorentz factor and Gamma-ray emission site","authors":"Ajay Sharma ,&nbsp;Aishwarya Sarath ,&nbsp;Sakshi Chaudhary ,&nbsp;Debanjan Bose","doi":"10.1016/j.jheap.2025.100452","DOIUrl":"10.1016/j.jheap.2025.100452","url":null,"abstract":"<div><div>We present a comprehensive temporal and spectral analysis of a few blazars using multi-wavelength observations. Rapid flux variations are quantified via the doubling/halving timescale method, revealing the shortest variability timescales of a few hours in <em>γ</em>-ray emissions. The broadband fractional variability is systematically computed and examined as a function of frequency, displaying a characteristic double-hump structure akin to the typical spectral energy distribution (SED) of blazars. To distinguish between different emission states, we utilize the Bayesian block algorithm, which effectively identifies distinct flux states for targeted spectral modeling. A one-zone leptonic emission framework is employed to model the broadband emission during these states. The minimum Doppler factors are estimated based on the shortest variability timescales observed in the <em>γ</em>-ray emissions. Under the external Compton scenario, we constrain the location of the gamma-ray emitting region and the Lorentz factor using three physical conditions: the upper limit on the jet collimation parameter, <span><math><mi>Γ</mi><mi>θ</mi><mo>&lt;</mo><mn>1</mn></math></span>; the upper limit on the synchrotron self-Compton contribution, <span><math><msub><mrow><mi>L</mi></mrow><mrow><mi>SSC</mi></mrow></msub><mo>≲</mo><msub><mrow><mi>L</mi></mrow><mrow><mi>X</mi></mrow></msub></math></span>; and the observational constraint on the cooling break energy, <span><math><msub><mrow><mi>E</mi></mrow><mrow><mi>cool</mi><mo>,</mo><mi>obs</mi></mrow></msub><mo>≲</mo><mn>100</mn></math></span> MeV.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"49 ","pages":"Article 100452"},"PeriodicalIF":10.5,"publicationDate":"2025-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144996138","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Charge constraint on M87* with twisted light","authors":"Fabiano Feleppa ,&nbsp;Fabrizio Tamburini ,&nbsp;Gaetano Lambiase","doi":"10.1016/j.jheap.2025.100455","DOIUrl":"10.1016/j.jheap.2025.100455","url":null,"abstract":"<div><div>We propose a novel method to constrain the electric charge of the supermassive black hole M87* by analyzing the orbital angular momentum content of the light it emits. By leveraging the established analogy between rotating spacetimes and inhomogeneous optical media, we derive a simple analytical formula that relates the average orbital angular momentum in the observed radiation to the black hole's charge-to-mass ratio. Applying this relation to existing observational data, we place an upper bound of <span><math><mi>Q</mi><mo>/</mo><mi>M</mi><mo>≲</mo><mn>0.39</mn></math></span> on the charge of M87*. While the analysis focuses on electric charge, which is used here purely as a theoretical example since astrophysical black holes are expected to be approximately neutral, the method is general and can be extended to constrain other types of charges – degrees of freedom that define distinct black hole solutions. These results demonstrate the potential of orbital angular momentum as a new fundamental degree of freedom to be exploited in astrophysics, providing a complementary and independent alternative to shadow-based techniques for probing the properties of rotating compact objects and testing gravity in the strong-field regime.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"49 ","pages":"Article 100455"},"PeriodicalIF":10.5,"publicationDate":"2025-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144925422","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Fermi-large area telescope detection of very high energy (>100 GeV) emission from misaligned jetted active galactic nuclei","authors":"Gunjan Tomar ,&nbsp;Vaidehi S. Paliya ,&nbsp;D.J. Saikia ,&nbsp;C.S. Stalin","doi":"10.1016/j.jheap.2025.100454","DOIUrl":"10.1016/j.jheap.2025.100454","url":null,"abstract":"<div><div>The detection of very-high-energy (VHE; &gt;100 GeV) <em>γ</em>-ray radiation from misaligned jetted Active Galactic Nuclei (AGN) challenges the emission models that primarily explain VHE emissions from beamed AGN, i.e., blazars. Using over 16 years of <em>Fermi</em>-Large Area Telescope (<em>Fermi</em>-LAT) Pass 8 data in the energy range 0.1−2 TeV, we systematically explore the VHE emission from a recently published sample of 160 radio galaxies. We identify 12 sources detected at <span><math><mo>&gt;</mo><mn>4</mn><mi>σ</mi></math></span> confidence level (test statistic or TS&gt;16), including nine with TS&gt;25 and two Fanaroff-Riley type II objects. This detected sample includes seven out of eight previously known VHE objects. Two radio galaxies are detected in the VHE band for the first time, and we identify three promising candidates with 16&lt;TS&lt;25. Additionally, 13 objects are identified as candidate VHE emitters with at least one VHE photon detected with the <em>Fermi</em>-LAT. These findings expand the sample of known VHE-emitting radio galaxies, whose multiwavelength follow-up observations can help provide insights into the emission mechanisms, jet physics, and the contribution of misaligned AGN to the extragalactic <em>γ</em>-ray background.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"49 ","pages":"Article 100454"},"PeriodicalIF":10.5,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144925421","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Empirical validation: Investigating the ΛsCDM model with new DESI BAO observations","authors":"Manish Yadav ,&nbsp;Archana Dixit ,&nbsp;Anirudh Pradhan ,&nbsp;M.S. Barak","doi":"10.1016/j.jheap.2025.100453","DOIUrl":"10.1016/j.jheap.2025.100453","url":null,"abstract":"<div><div>The ΛCDM model has long served as the cornerstone of modern cosmology, offering an elegant and successful framework for interpreting a wide range of cosmological observations. However, the rise of high-precision datasets has revealed statistically significant tensions, most notably the Hubble tension and the <span><math><msub><mrow><mi>S</mi></mrow><mrow><mn>8</mn></mrow></msub></math></span> discrepancy, which challenge the completeness of this standard model. In this context, we explore the <span><math><msub><mrow><mi>Λ</mi></mrow><mrow><mi>s</mi></mrow></msub></math></span>CDM model—an extension of ΛCDM featuring a single additional parameter, <span><math><msub><mrow><mi>z</mi></mrow><mrow><mi>†</mi></mrow></msub></math></span>, corresponding to a sign-switching cosmological constant. This minimal modification aims to alleviate key observational tensions without compromising the model's overall coherence. Recent findings present in the literature indicate that the <span><math><msub><mrow><mi>Λ</mi></mrow><mrow><mi>s</mi></mrow></msub></math></span>CDM model not only provides a better fit to Lyman-<em>α</em> forest data for <span><math><msub><mrow><mi>z</mi></mrow><mrow><mi>†</mi></mrow></msub><mo>&lt;</mo><mn>2.3</mn></math></span>, but also accommodates both the SH0ES measurement of <span><math><msub><mrow><mi>H</mi></mrow><mrow><mn>0</mn></mrow></msub></math></span> and the angular diameter distance to the last scattering surface when 2D BAO data are included. We present a comprehensive analysis combining the full Planck 2018 CMB data, the Pantheon Type Ia Supernovae sample, and the recently released Baryon Acoustic Oscillation (BAO) measurements from the Dark Energy Spectroscopic Instrument (DESI). Our finding reveal that the Preliminary DESI results, a possible 3.9<em>σ</em> deviation from ΛCDM expectations, reinforce the importance of exploring such dynamic dark energy frameworks. In sum, our study underscores the potential of <span><math><msub><mrow><mi>Λ</mi></mrow><mrow><mi>s</mi></mrow></msub></math></span>CDM to reconcile multiple cosmological tensions and sheds light on the role of upcoming high-precision observations in reshaping our understanding of the universe's expansion history and the nature of dark energy.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"49 ","pages":"Article 100453"},"PeriodicalIF":10.5,"publicationDate":"2025-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144922633","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ultra-high energy cosmic rays with UFA-15 source model in Bumblebee gravity theory","authors":"Swaraj Pratim Sarmah,&nbsp;Pranjal Sarmah,&nbsp;Umananda Dev Goswami","doi":"10.1016/j.jheap.2025.100451","DOIUrl":"10.1016/j.jheap.2025.100451","url":null,"abstract":"<div><div>We explore the effects of Bumblebee gravity on the propagation of ultra-high energy cosmic rays (UHECRs) using astrophysical sources modeled in the Unger-Farrar-Anchordoqui (UFA) framework (2015), which includes star formation rate (SFR), gamma-ray bursts (GRBs), and active galactic nuclei (AGN). We compute the density enhancement factor for various source separations distances (<span><math><msub><mrow><mi>d</mi></mrow><mrow><mtext>s</mtext></mrow></msub></math></span>s) up to 100 Mpc within the Bumblebee gravity scenario. Additionally, we calculate the CRs flux and their suppression, goodness-of-fit values obtained from comparisons with observational data from the Pierre Auger Observatory (PAO) and the Telescope Array experiment data for the flux and the Levenberg-Marquardt algorithm for suppression. The anisotropy in the CRs arrival directions is examined, with corresponding goodness-of-fit values obtained from the PAO surface detector data (SD 750 and SD 1500). Finally, we present skymaps of flux and anisotropy under different model assumptions, providing insights into the observational signatures of UHECRs in Bumblebee gravity. We show that Bumblebee gravity stands as a viable cosmological model for explaining key observational features of UHECRs, including spectrum, composition and anisotropy. Our results show that increasing the Bumblebee gravity parameter <em>l</em> enhances the density factor <em>ξ</em>, particularly at low energies, highlighting Lorentz violation's impact on CRs' propagation. Larger <span><math><msub><mrow><mi>d</mi></mrow><mrow><mtext>s</mtext></mrow></msub></math></span> values amplify deviations from the ΛCDM model, with AGN sources dominating at high energies and GRB/SFR sources at lower energies. The skymaps indicate the structured flux patterns at large <span><math><msub><mrow><mi>d</mi></mrow><mrow><mtext>s</mtext></mrow></msub></math></span> and structured anisotropies at higher energies.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"49 ","pages":"Article 100451"},"PeriodicalIF":10.5,"publicationDate":"2025-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144896752","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"NuSTAR discovers a long type-I X-ray burst from the clocked burster GS 1826-24","authors":"Aditya S. Mondal ,&nbsp;Mayukh Pahari ,&nbsp;Gulab C. Dewangan","doi":"10.1016/j.jheap.2025.100450","DOIUrl":"10.1016/j.jheap.2025.100450","url":null,"abstract":"<div><div>The source GS 1826-24 is a neutron star low mass X-ray binary known as the “clocked burster” because of its extremely regular bursting behavior. We report on the detection of a long type-I X-ray burst from this source. We perform a detailed spectroscopic analysis of the long X-ray burst, lasting for ∼600 s, seen in the <em>NuSTAR</em> observation carried out on 2022 September. The persistent emission is well described by an absorbed thermal Comptonization model <span>nthcomp</span>, and the source exhibits a soft spectral state during this observation. The observed burst exhibits a rise time of ∼25 s and a decay time of ∼282 s. The time-resolved spectroscopy of the burst shows a significant departure from a pure thermal spectrum and is described with a model consisting of a varying-temperature blackbody plus an evolving persistent emission component. We observe a significant enhancement in the persistent emission during the burst. The enhancement of the pre-burst persistent flux is possibly due to Poynting-Robertson drag or coronal reprocessing. At the peak of the burst, the blackbody temperature and the blackbody emitting radius reached a maximum of <span><math><mn>2.10</mn><mo>±</mo><mn>0.07</mn></math></span> keV and <span><math><mn>5.5</mn><mo>±</mo><mn>2.1</mn></math></span> km, respectively. The peak flux (<span><math><msub><mrow><mi>F</mi></mrow><mrow><mi>p</mi><mi>e</mi><mi>a</mi><mi>k</mi></mrow></msub></math></span>) during the burst is <span><math><mo>≈</mo><mn>2.4</mn><mo>×</mo><msup><mrow><mn>10</mn></mrow><mrow><mo>−</mo><mn>8</mn></mrow></msup></math></span> ergs cm⁻² s⁻¹, which corresponds to a luminosity of <span><math><mo>≈</mo><mn>9.7</mn><mo>×</mo><msup><mrow><mn>10</mn></mrow><mrow><mn>37</mn></mrow></msup></math></span> ergs s⁻¹.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"49 ","pages":"Article 100450"},"PeriodicalIF":10.5,"publicationDate":"2025-08-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144863744","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}