Journal of High Energy Astrophysics最新文献

{"title":"Pair production due to absorption of 2.2 MeV photons in magnetospheres of X-ray pulsars","authors":"Emir Tataroglu ,&nbsp;Alexander A. Mushtukov","doi":"10.1016/j.jheap.2025.100420","DOIUrl":"10.1016/j.jheap.2025.100420","url":null,"abstract":"<div><div>Accretion onto strongly magnetized neutron stars in X-ray pulsars (XRPs) produces intense X-ray emission and gamma-ray photons, the latter arising from nuclear reactions and high-energy particle collisions in the stellar atmosphere. These gamma-rays interact with the magnetic field via one- and two-photon pair creation processes, generating electron-positron pairs. We investigate one-photon pair production in sub-critical XRPs, with a focus on how surface magnetic field strength affects gamma-ray absorption in the magnetosphere. Using general relativistic photon trajectory simulations, we map the spatial distribution of pair creation sites and quantify absorption efficiencies. We find that XRPs with surface fields <span><math><mi>B</mi><mo>≲</mo><msup><mrow><mn>10</mn></mrow><mrow><mn>12</mn></mrow></msup><mspace></mspace><mi>G</mi></math></span> are largely transparent to 2.2<!--> <!-->MeV gamma-rays, while fields <span><math><mi>B</mi><mo>≳</mo><mn>3</mn><mo>×</mo><msup><mrow><mn>10</mn></mrow><mrow><mn>12</mn></mrow></msup><mspace></mspace><mi>G</mi></math></span> lead to efficient absorption within a few tens of centimeters from the surface. For lower field strengths, absorption can occur at larger distances and outside the accretion column, offering a potential channel for radio emission. Our results provide new insight into the interplay between nuclear processes, magnetospheric structure, and multiwavelength radiation in XRPs.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"48 ","pages":"Article 100420"},"PeriodicalIF":10.2,"publicationDate":"2025-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144579208","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":"Balancing accessibility and quality: How high energy astrophysics supports a diverse scientific community","authors":"","doi":"10.1016/j.jheap.2025.100423","DOIUrl":"10.1016/j.jheap.2025.100423","url":null,"abstract":"","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"49 ","pages":"Article 100423"},"PeriodicalIF":10.5,"publicationDate":"2025-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145095332","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":"Corrigendum to “LEIA in Flight Performance and Variability of Flux and Spectra of Some Bright X-ray Sources in the Galactic Plane” [Journal of High Energy Astrophysics,Volume 47, Article Number, 100371]","authors":"Zi-Zeng Lv ,&nbsp;Chen Wang ,&nbsp;Jin-Yuan Liao ,&nbsp;Yuan Liu ,&nbsp;Shuang-Nan Zhang ,&nbsp;Huaqing Cheng ,&nbsp;Zhi-Xing Ling ,&nbsp;He-Yang Liu ,&nbsp;Hai-Wu Pan ,&nbsp;Wei-Min Yuan ,&nbsp;Chen Zhang","doi":"10.1016/j.jheap.2025.100421","DOIUrl":"10.1016/j.jheap.2025.100421","url":null,"abstract":"","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"48 ","pages":"Article 100421"},"PeriodicalIF":10.2,"publicationDate":"2025-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144680363","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":"Exponential decay vs. power-law decay for the prompt emission of GRB 221009A","authors":"Yuan-Yuan Zuo ,&nbsp;Duan-Yuan Gao ,&nbsp;Yuan-Chuan Zou ,&nbsp;Dong-Jie Liu ,&nbsp;Peng-Wei Zhao","doi":"10.1016/j.jheap.2025.100419","DOIUrl":"10.1016/j.jheap.2025.100419","url":null,"abstract":"<div><div>The pulse profile of Gamma-ray bursts (GRBs) is often described as fast rise and exponential decay (FRED). However, the exponential decay feature can be decisively identified from power-law decay only if the flux decays several orders of magnitude. GRB 221009A, the brightest GRB ever observed, should be able to test the FRED feature. Using data from <em>Fermi</em>-GBM, we examined the decay pattern of the burst across different energy ranges. Power-law and exponential models were fitted to different segments of the decay phase, and the posterior distributions of the model parameters were estimated using Markov Chain Monte Carlo (MCMC) method. The power-law decay fits the light curve better than the exponential decay in both the precursor and the main burst. This implies that they may originate from the same physical mechanism, which may improve our understanding of the mechanisms of GRB emission and the dynamics of the central engine.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"48 ","pages":"Article 100419"},"PeriodicalIF":10.2,"publicationDate":"2025-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144579207","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":"Strong gravitational lensing by SMBHs in Hernquist dark matter halos: Implications from EHT observations","authors":"Amna Ali ,&nbsp;Ammuthavali Ramasamya ,&nbsp;Sushant G. Ghosh","doi":"10.1016/j.jheap.2025.100418","DOIUrl":"10.1016/j.jheap.2025.100418","url":null,"abstract":"<div><div>We examine strong gravitational lensing signatures of supermassive black holes (SMBHs) embedded in Hernquist-type dark matter halos, comparing theoretical predictions with Event Horizon Telescope (EHT) observations of M87^⁎ and Sgr A^⁎. Our analysis demonstrates that a Hernquist halo with <span><math><msub><mrow><mi>ρ</mi></mrow><mrow><mi>s</mi></mrow></msub><mo>=</mo><mn>1.4</mn><msup><mrow><mi>M</mi></mrow><mrow><mo>−</mo><mn>2</mn></mrow></msup></math></span> and <span><math><msub><mrow><mi>r</mi></mrow><mrow><mi>s</mi></mrow></msub><mo>=</mo><mn>0.5</mn><mi>M</mi></math></span> increases the photon sphere radius by 20.3% (from 3<em>M</em> to 3.61<em>M</em>) and critical impact parameter from 5.196<em>M</em> to 10.471<em>M</em>, while modifying strong deflection coefficients to <span><math><mover><mrow><mi>a</mi></mrow><mrow><mo>¯</mo></mrow></mover><mo>=</mo><mn>1.02629</mn></math></span> and <span><math><mover><mrow><mi>b</mi></mrow><mrow><mo>¯</mo></mrow></mover><mo>=</mo><mo>−</mo><mn>1.32863</mn></math></span> (vs. Schwarzschild values 1 and −1.34983). EHT data constrain the central density to <span><math><msub><mrow><mi>ρ</mi></mrow><mrow><mi>s</mi></mrow></msub><mo>=</mo><mn>2.37</mn><mo>±</mo><mn>0.30</mn><msup><mrow><mi>M</mi></mrow><mrow><mo>−</mo><mn>2</mn></mrow></msup></math></span> (<span><math><mn>5.2</mn><mo>±</mo><mn>0.7</mn><mo>×</mo><msup><mrow><mn>10</mn></mrow><mrow><mo>−</mo><mn>3</mn></mrow></msup><msub><mrow><mi>M</mi></mrow><mrow><mo>⊙</mo></mrow></msub><mo>/</mo><msup><mrow><mtext>pc</mtext></mrow><mrow><mn>3</mn></mrow></msup></math></span>) and scale radius to <span><math><msub><mrow><mi>r</mi></mrow><mrow><mi>s</mi></mrow></msub><mo>=</mo><msubsup><mrow><mn>0.53</mn></mrow><mrow><mo>−</mo><mn>0.09</mn></mrow><mrow><mo>+</mo><mn>0.12</mn></mrow></msubsup><mi>M</mi></math></span> (3.25–4.25 pc) for M87^⁎, and <span><math><msub><mrow><mi>ρ</mi></mrow><mrow><mi>s</mi></mrow></msub><mo>=</mo><mn>2.08</mn><mo>±</mo><mn>0.18</mn><msup><mrow><mi>M</mi></mrow><mrow><mo>−</mo><mn>2</mn></mrow></msup></math></span> (<span><math><mn>0.18</mn><mo>±</mo><mn>0.02</mn><msub><mrow><mi>M</mi></mrow><mrow><mo>⊙</mo></mrow></msub><mo>/</mo><msup><mrow><mtext>pc</mtext></mrow><mrow><mn>3</mn></mrow></msup></math></span>) with <span><math><msub><mrow><mi>r</mi></mrow><mrow><mi>s</mi></mrow></msub><mo>=</mo><msubsup><mrow><mn>0.48</mn></mrow><mrow><mo>−</mo><mn>0.11</mn></mrow><mrow><mo>+</mo><mn>0.15</mn></mrow></msubsup><mi>M</mi></math></span> (0.019–0.025 pc) for Sgr A^⁎, excluding <span><math><msub><mrow><mi>ρ</mi></mrow><mrow><mi>s</mi></mrow></msub><mo>&gt;</mo><mn>2.97</mn><msup><mrow><mi>M</mi></mrow><mrow><mo>−</mo><mn>2</mn></mrow></msup></math></span> (M87^⁎) and <span><math><mo>&gt;</mo><mn>2.44</mn><msup><mrow><mi>M</mi></mrow><mrow><mo>−</mo><mn>2</mn></mrow></msup></math></span> (Sgr A^⁎) at 95% CL. Characteristic signatures include 12.8–18.3% larger Ei","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"48 ","pages":"Article 100418"},"PeriodicalIF":10.2,"publicationDate":"2025-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144563645","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":"X-ray flux variability of Blazar Mrk 501 observed using NuSTAR","authors":"S.A. Ata ,&nbsp;Nasser M. Ahmed ,&nbsp;M.M. Beheary ,&nbsp;F.Y. Kamal","doi":"10.1016/j.jheap.2025.100417","DOIUrl":"10.1016/j.jheap.2025.100417","url":null,"abstract":"<div><div>We present a detailed spectral study of 12 X-ray NuSTAR observations of the BL Lac object Markarian (or Mrk) 501, spanning a period from 2013 to 2022. We extracted source spectra within an 80-arcseconds radius around the source center and background with a radius of 300-arcseconds. The X-ray flux variability of our sample was derived by extracting the Blazar Mrk 501 sample spectra and fitting them with six models in the XSPEC package; these models yielded similar results. The spectral models covered various physical processes, including thermal bremsstrahlung emission. In addition, we investigated the time variations of the model parameters. By comparing the fits from the six models, we found that the zpowerlw model is the best representation of the data in the low state, while the bremsstrahlung-zpowerlaw model best represents the data across all energy ranges. To verify the X-ray variability of our data, we fit their spectra, extracted using the same method from the same instrument, with the same model to estimate their X-ray luminosity and flux. To verify the variability of the estimated fluxes, we fitted them using the bremsstrahlung-zpowerlaw model and found clear variability over the 12 observations. The bremsstrahlung-zpowerlaw model was the best model fitting the data in the 3 – 50 keV band. The highest variability was found in observation 60002024006, with a flux variability of 39.72 × <span><math><msup><mrow><mn>10</mn></mrow><mrow><mo>−</mo><mn>11</mn></mrow></msup></math></span> (erg<!--> <!-->cm⁻² <!-->s⁻¹). While the lowest variability was found in observation 60466006002, with a flux variability of 1.34 × <span><math><msup><mrow><mn>10</mn></mrow><mrow><mo>−</mo><mn>11</mn></mrow></msup></math></span> (erg<!--> <!-->cm⁻² <!-->s⁻¹), making the flux variability range 38.38 × <span><math><msup><mrow><mn>10</mn></mrow><mrow><mo>−</mo><mn>11</mn></mrow></msup></math></span> (erg<!--> <!-->cm⁻² <!-->s⁻¹).</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"48 ","pages":"Article 100417"},"PeriodicalIF":10.2,"publicationDate":"2025-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144518342","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":"Development of source-dependent gamma-ray image parameters using Generative Adversarial Network (GAN) for the MACE telescope and its implications","authors":"Manas Pratim Das ,&nbsp;V.K. Dhar ,&nbsp;Anudeep Singh ,&nbsp;N. Bhatt ,&nbsp;K.K. Yadav","doi":"10.1016/j.jheap.2025.100416","DOIUrl":"10.1016/j.jheap.2025.100416","url":null,"abstract":"<div><div>In the field of Very High Energy (VHE) gamma-ray astronomy using the Imaging Atmospheric Cherenkov Technique (IACT), the main challenge is to elicit the faint gamma-ray signal from a huge deluge of Cosmic Ray (CR) signals. For this purpose, an extensive simulation database of <em>γ</em>-ray-induced extensive air shower (EAS) images across a wide energy range (30 GeV - a few 10 TeVs) must be generated. Moreover, different celestial <em>γ</em>-ray sources differ in flux and power-law spectral indices.</div><div>However, the position of the gamma-ray events in the image parameter hyperspace changes as per the gamma-ray source spectral profile. Hence, depending on the gamma-ray sources' spectral indices, the gamma domain cuts are subject to change. The gamma domain cuts proposed for a particular source (the Crab Nebula, for example) applied to a source of different spectral indices will inevitably result in an erroneous flux calculation of the source. The Generative Adversarial Network (GAN) is a potent unsupervised and generative Machine Learning (ML) tool to generate synthetic gamma-ray image parameters for sources with different spectral indices. This article will discuss the rationale behind developing a source-dependent database generation using the GAN and highlight its importance for the MACE telescope.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"48 ","pages":"Article 100416"},"PeriodicalIF":10.2,"publicationDate":"2025-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144490061","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":"Two-component jet model for the afterglow emission of GRB 201216C and GRB 221009A and implications for jet structure of very-high-energy gamma-ray bursts","authors":"Yuri Sato ,&nbsp;Kohta Murase ,&nbsp;Yutaka Ohira ,&nbsp;Susumu Inoue ,&nbsp;Ryo Yamazaki","doi":"10.1016/j.jheap.2025.100415","DOIUrl":"10.1016/j.jheap.2025.100415","url":null,"abstract":"<div><div>In recent years, afterglow emission in the very-high-energy (VHE) band above 100 GeV has been clearly detected for at least five gamma-ray bursts (GRBs 180720B, 190114C, 190829A, 201216C and 221009A). For some of these VHE GRBs, we previously proposed a two-component jet model, consisting of two uniform jets with narrow and wide opening angles to explain their multiwavelength afterglows including VHE gamma rays. In this paper, we show that the VHE spectra and light curves of GRBs 201216C and 221009A can also be reasonably explained by our two-component jet model, based on two top-hat jets propagating into a constant-density circumburst medium. We find that for the five VHE GRBs, the collimation-corrected kinetic energies of the narrow and wide jets have typical values of <span><math><mn>5</mn><mo>×</mo><msup><mrow><mn>10</mn></mrow><mrow><mn>49</mn></mrow></msup></math></span> erg and <span><math><mn>5</mn><mo>×</mo><msup><mrow><mn>10</mn></mrow><mrow><mn>50</mn></mrow></msup></math></span> erg, respectively. We discuss the similarities and differences among the VHE GRBs, and the implications for the structure of their jets. In agreement with previous studies, the narrow jet of GRB 221009A has an atypically small opening angle, so that its intrinsic, collimation-corrected energy remains within a plausible range despite the unusually large isotropic-equivalent energy.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"48 ","pages":"Article 100415"},"PeriodicalIF":10.2,"publicationDate":"2025-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144321620","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":"Testing the quantum equivalence principle with gravitational waves","authors":"Saurya Das ,&nbsp;Mitja Fridman ,&nbsp;Gaetano Lambiase","doi":"10.1016/j.jheap.2025.100413","DOIUrl":"10.1016/j.jheap.2025.100413","url":null,"abstract":"<div><div>We study modifications of gravitational wave observables, such as the wave amplitude and frequency, which follow from the quantum equivalence principle, and are expressed in terms of the inertial, gravitational and rest masses of the LIGO/Virgo mirrors. We provide bounds on the violations of the quantum equivalence principle by comparing the results with the most resolved gravitational wave events observed by the LIGO/Virgo collaboration. The formalism is equally applicable to other future ground and space-based gravitational wave detectors.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"48 ","pages":"Article 100413"},"PeriodicalIF":10.2,"publicationDate":"2025-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144270151","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":"Modelling self-gravitating systems in f(R,G) gravity with anisotropic pressure and Tolman-Kuchowicz background","authors":"M. Ilyas ,&nbsp;Zaib Un Nisa Shinwari","doi":"10.1016/j.jheap.2025.100414","DOIUrl":"10.1016/j.jheap.2025.100414","url":null,"abstract":"<div><div>The present study offers a comprehensive analysis of anisotropic matter distributions and various physical properties of compact stars within the framework of <span><math><mi>f</mi><mo>(</mo><mi>R</mi><mo>,</mo><mi>G</mi><mo>)</mo></math></span>-gravity. To thoroughly explore these aspects, we focus on three specific compact stellar objects: Her X-1 (CS1), SAX J1808.4-3658 (CS2), and 4U 1820-30 (CS3). Using three distinct models of <span><math><mi>f</mi><mo>(</mo><mi>R</mi><mo>,</mo><mi>G</mi><mo>)</mo></math></span>-gravity, we compute the relevant physical characteristics of these stars. For a systematic approach, the <span><math><mi>f</mi><mo>(</mo><mi>R</mi><mo>,</mo><mi>G</mi><mo>)</mo></math></span>-gravity framework is decomposed into two components: <span><math><msub><mrow><mi>f</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>(</mo><mi>R</mi><mo>)</mo></math></span> and <span><math><msub><mrow><mi>f</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>(</mo><mi>G</mi><mo>)</mo></math></span>. The <em>R</em>-dependent term, <span><math><msub><mrow><mi>f</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>(</mo><mi>R</mi><mo>)</mo></math></span>, is modelled following the Hu-Sawicki formalism, while the <em>G</em>-dependent term, <span><math><msub><mrow><mi>f</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>(</mo><mi>G</mi><mo>)</mo></math></span>, incorporates logarithmic and power-law formulations, leading to three viable gravitational models. We employ graphical analysis to examine the physical behaviour of these compact stars under the proposed modified gravity scenarios.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"48 ","pages":"Article 100414"},"PeriodicalIF":10.2,"publicationDate":"2025-06-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144307326","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}