Journal of High Energy Astrophysics最新文献

{"title":"LEIA in flight performance and variability of flux and spectra of some bright X-ray sources in the Galactic plane","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.2025.100371","DOIUrl":"10.1016/j.jheap.2025.100371","url":null,"abstract":"<div><div>We report the results of the first 2-year observations of LEIA in the Galactic plane and demonstrate its excellent performance. We select 34 sources for detailed analysis of their flux and spectral variability. Systematic errors are calculated and the observational performance differences between CMOS15 and CMOS16 are corrected. During the analysis of these sources, excess variance and standard <span><math><msup><mrow><mi>χ</mi></mrow><mrow><mn>2</mn></mrow></msup></math></span> tests are applied to characterize flux and spectral variability, respectively, and the distributions and their interrelations are analyzed. A variable flux is observed in most sources, with a more significant difference in flux variability observed closer to the Galactic Center. Two methods are employed to characterize spectral variability: fluctuations in the Hardness Ratio (HR) derived from count rates in the high-to-low energy bands, and variability in the photon index (Γ) obtained from spectral fitting. The results from both methods are broadly consistent. The findings suggest that the spectra of most XRBs are variable. Statistical analysis of flux and spectral variability for the sample sources reveals no significant correlation between the two. As a result, the first 2-year XRBs catalog of LEIA in the Galactic plane is presented. At the same time, the analysis of the sources indicate that the observation data of LEIA are usable and valuable, fulfilling its mission as the pathfinder of lobster-eye Wide-field X-ray Telescope onboard the Einstein Probe mission.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"47 ","pages":"Article 100371"},"PeriodicalIF":10.2,"publicationDate":"2025-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143704087","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":"Cosmographic and thermodynamics analysis of five dimensional EChS gravity","authors":"Nadeem Azhar ,&nbsp;Abdul Jawad ,&nbsp;Iftikhar Ahmed ,&nbsp;Mohammad Mahtab Alam ,&nbsp;Sanjar Shaymatov","doi":"10.1016/j.jheap.2025.100369","DOIUrl":"10.1016/j.jheap.2025.100369","url":null,"abstract":"<div><div>In this study, we explore the five-dimensional Einstein-Chern-Simons gravity (EChS) gravity in the context of a flat FRW universe. This framework, derived by incorporating higher-dimensional topological invariants and gauge symmetries, serves as a compelling extension of general relativity. We employ the holographic dark energy model, using the Hubble horizon as the infrared cutoff, to investigate its cosmological implications. The distinctiveness of this approach lies in its inclusion of higher-order curvature corrections and alignment with holographic principles, making it a robust tool for analyzing modified gravity effects and cosmic evolution. Additionally, we examine various interaction terms <em>Q</em> and analyze key cosmological parameters, including the coincidence parameter, equation of state parameter, Hubble parameter, and deceleration parameter, to understand the universe's current dynamics. Lastly, the generalized second law of thermodynamics is evaluated to assess the thermodynamic behavior of the model. Notably, the findings of this research exhibit excellent agreement with recent observational data.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"47 ","pages":"Article 100369"},"PeriodicalIF":10.2,"publicationDate":"2025-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143696793","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":"Photons shells inner structure and causal properties","authors":"D. Pugliese,&nbsp;Z. Stuchlík","doi":"10.1016/j.jheap.2025.100368","DOIUrl":"10.1016/j.jheap.2025.100368","url":null,"abstract":"<div><div>We shed light on some causal properties of the Kerr super-spinnars emerging through the investigation of the spacetimes photon shells. We define inner structure of the spacetime photon shell, constituted by regions distinguished by specific characteristics of the photons paths. These regions are reflected in the singularity shadow boundaries studied, in particular, in relation to repulsive gravity effects, known in a specific class of slowly spinning super-spinnars. Counter–rotating and co–rotating photons are particularly investigated. Super fast spinning solutions are characterized by “faint” shadow boundaries. The properties emerging from this analysis could be observed from specific regions of the spacetimes photon spheres boundaries. Slowly spinning super-spinnars, with (dimensionless) spin <span><math><mn>1</mn><mo>&lt;</mo><mi>a</mi><mo>≤</mo><mn>1.17996</mn></math></span>, are characterized by an articulated photon shell inner structure, evidenced close to the singularity rotational axis. This structure is analyzed for all view angles.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"47 ","pages":"Article 100368"},"PeriodicalIF":10.2,"publicationDate":"2025-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143644981","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":"Einstein clusters as dark matter fluid-like models for constructing new wormhole solutions in f(R,Lm,T) gravity","authors":"A. Errehymy ,&nbsp;Y. Khedif ,&nbsp;M. Daoud ,&nbsp;K. Myrzakulov ,&nbsp;A.-H. Abdel-Aty ,&nbsp;K.S. Nisar","doi":"10.1016/j.jheap.2025.100370","DOIUrl":"10.1016/j.jheap.2025.100370","url":null,"abstract":"<div><div>This study explores traversable wormholes in <span><math><mi>f</mi><mo>(</mo><mi>R</mi><mo>,</mo><msub><mrow><mi>L</mi></mrow><mrow><mi>m</mi></mrow></msub><mo>,</mo><mi>T</mi><mo>)</mo></math></span> gravity, which modifies traditional gravity by integrating the matter Lagrangian and the trace of the energy-momentum tensor. We define this modification as <span><math><mi>f</mi><mo>(</mo><mi>R</mi><mo>,</mo><msub><mrow><mi>L</mi></mrow><mrow><mi>m</mi></mrow></msub><mo>,</mo><mi>T</mi><mo>)</mo><mo>=</mo><mi>R</mi><mo>+</mo><mi>λ</mi><msub><mrow><mi>L</mi></mrow><mrow><mi>m</mi></mrow></msub><mo>+</mo><mi>χ</mi><mi>T</mi></math></span>, where <em>λ</em> and <em>χ</em> are coupling constants. Focusing on <span><math><msub><mrow><mi>L</mi></mrow><mrow><mi>m</mi></mrow></msub><mo>=</mo><mo>−</mo><mi>ρ</mi></math></span>, where <em>ρ</em> represents the energy density and a constant redshift function <span><math><mover><mrow><mi>ν</mi></mrow><mrow><mo>ˆ</mo></mrow></mover><mo>(</mo><mi>r</mi><mo>)</mo></math></span>, we investigate the properties and gravitational lensing of Einstein clusters, formed by weakly interacting massive particles as dark matter halos. These clusters exhibit tangential pressure dominance, characterized by an equation of state where the tangential pressure <span><math><msub><mrow><mi>P</mi></mrow><mrow><mi>t</mi></mrow></msub></math></span> is proportional to the energy density <em>ρ</em> (i.e., <span><math><msub><mrow><mi>P</mi></mrow><mrow><mi>t</mi></mrow></msub><mo>=</mo><mi>σ</mi><mi>ρ</mi></math></span>, where <em>σ</em> is a constant), which can adjust anisotropy to model galactic rotation curves effectively. We derive the shape function under the influence of Einstein clusters and analyze the null energy condition's effect on matter distribution in anisotropic fluids. The stability of the resulting wormhole solutions is confirmed via the Tolman-Oppenheimer-Volkoff formalism. Our analysis of photon deflection along null geodesics shows that for <em>σ</em> in the range <span><math><mo>[</mo><mn>0</mn><mo>,</mo><mn>0.25</mn><mo>]</mo></math></span>, the deflection angle is negative, causing photons to bend outward. In contrast, for <em>σ</em> in the range <span><math><mo>[</mo><mo>−</mo><mn>0.25</mn><mo>,</mo><mn>0</mn><mo>]</mo></math></span>, the angles are positive, indicating that light rays curve inward toward the wormhole throat.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"47 ","pages":"Article 100370"},"PeriodicalIF":10.2,"publicationDate":"2025-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143696794","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":"Shadows and parameter estimation of rotating quantum corrected black holes and constraints from EHT observation of M87* and Sgr A*","authors":"Heena Ali ,&nbsp;Shafqat Ul Islam ,&nbsp;Sushant G. Ghosh","doi":"10.1016/j.jheap.2025.100367","DOIUrl":"10.1016/j.jheap.2025.100367","url":null,"abstract":"&lt;div&gt;&lt;div&gt;The scarcity of quantum gravity (QG) inspired rotating black holes limits the progress of testing QG through Event Horizon Telescope (EHT) observations. The EHT imaged the supermassive black holes, Sgr A* and M87*, revealing an angular shadow diameter of &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;d&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;s&lt;/mi&gt;&lt;mi&gt;h&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;48.7&lt;/mn&gt;&lt;mo&gt;±&lt;/mo&gt;&lt;mn&gt;7&lt;/mn&gt;&lt;mi&gt;μ&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt;as with a black hole mass of &lt;span&gt;&lt;math&gt;&lt;mi&gt;M&lt;/mi&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;msubsup&gt;&lt;mrow&gt;&lt;mn&gt;4.0&lt;/mn&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mn&gt;0.6&lt;/mn&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mo&gt;+&lt;/mo&gt;&lt;mn&gt;1.1&lt;/mn&gt;&lt;/mrow&gt;&lt;/msubsup&gt;&lt;mo&gt;×&lt;/mo&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mn&gt;10&lt;/mn&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;6&lt;/mn&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;mi&gt;M&lt;/mi&gt;&lt;mo&gt;⊙&lt;/mo&gt;&lt;/math&gt;&lt;/span&gt; for Sgr A*. For M87*, with a mass of &lt;span&gt;&lt;math&gt;&lt;mi&gt;M&lt;/mi&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mn&gt;6.5&lt;/mn&gt;&lt;mo&gt;±&lt;/mo&gt;&lt;mn&gt;0.7&lt;/mn&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;mo&gt;×&lt;/mo&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mn&gt;10&lt;/mn&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;9&lt;/mn&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;M&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mo&gt;⊙&lt;/mo&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt;, the EHT measured an angular diameter of &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;θ&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;d&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;42&lt;/mn&gt;&lt;mo&gt;±&lt;/mo&gt;&lt;mn&gt;3&lt;/mn&gt;&lt;mi&gt;μ&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt;as. We present rotating quantum-corrected black hole (RQCBH) spacetimes with an additional QC parameter &lt;em&gt;α&lt;/em&gt; and constrain it by EHT observations. For angular shadow diameter (&lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;d&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;s&lt;/mi&gt;&lt;mi&gt;h&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt;) of Sgr A* at &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;θ&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;o&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mn&gt;50&lt;/mn&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;/math&gt;&lt;/span&gt;, the bounds are &lt;span&gt;&lt;math&gt;&lt;mn&gt;0.0&lt;/mn&gt;&lt;mo&gt;≤&lt;/mo&gt;&lt;mi&gt;α&lt;/mi&gt;&lt;mo&gt;≤&lt;/mo&gt;&lt;mn&gt;1.443&lt;/mn&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mi&gt;M&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;/math&gt;&lt;/span&gt; and &lt;span&gt;&lt;math&gt;&lt;mi&gt;a&lt;/mi&gt;&lt;mo&gt;∈&lt;/mo&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;mo&gt;,&lt;/mo&gt;&lt;mn&gt;0.8066&lt;/mn&gt;&lt;mi&gt;M&lt;/mi&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/math&gt;&lt;/span&gt;. For &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;θ&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;o&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mn&gt;90&lt;/mn&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;/math&gt;&lt;/span&gt;, the bounds are &lt;span&gt;&lt;math&gt;&lt;mn&gt;0.0&lt;/mn&gt;&lt;mo&gt;≤&lt;/mo&gt;&lt;mi&gt;α&lt;/mi&gt;&lt;mo&gt;≤&lt;/mo&gt;&lt;mn&gt;1.447&lt;/mn&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mi&gt;M&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;/math&gt;&lt;/span&gt; and &lt;span&gt;&lt;math&gt;&lt;mi&gt;a&lt;/mi&gt;&lt;mo&gt;∈&lt;/mo&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;mo&gt;,&lt;/mo&gt;&lt;mn&gt;0.894&lt;/mn&gt;&lt;mi&gt;M&lt;/mi&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/math&gt;&lt;/span&gt;. While for M87* at inclination &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;θ&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;o&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mn&gt;17&lt;/mn&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;/math&gt;&lt;/span&gt;, the bounds are &lt;span&gt;&lt;math&gt;&lt;mi&gt;a&lt;/mi&gt;&lt;mo&gt;∈&lt;/mo&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;mo&gt;,&lt;/mo&gt;&lt;mn&gt;0.8511&lt;/mn&gt;&lt;mi&gt;M&lt;/mi&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/math&gt;&lt;/span&gt; at &lt;span&gt;&lt;math&gt;&lt;mi&gt;α&lt;/mi&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;/math&gt;&lt;/span&gt; and &lt;span&gt;&lt;math&gt;&lt;mi&gt;a&lt;/mi&gt;&lt;mo&gt;∈&lt;/mo&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;mo&gt;,&lt;/mo&gt;&lt;mn&gt;0.6157&lt;/mn&gt;&lt;mi&gt;M&lt;/mi&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/math&gt;&lt;/span&gt; at &lt;span&gt;&lt;math&gt;&lt;mi&gt;α&lt;/mi&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;0.8985&lt;/mn&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mi&gt;M&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;/math&gt;&lt;/span&gt;. For &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;θ&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;o&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;msup&gt;","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"47 ","pages":"Article 100367"},"PeriodicalIF":10.2,"publicationDate":"2025-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143644983","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":"Search for spatial coincidence between IceCube neutrinos and gamma-ray bright red dwarfs","authors":"Fathima Shifa M,&nbsp;Shantanu Desai","doi":"10.1016/j.jheap.2025.100366","DOIUrl":"10.1016/j.jheap.2025.100366","url":null,"abstract":"<div><div>We search for a spatial coincidence between high energy neutrinos detected by the IceCube neutrino detector and ten red dwarfs which have been observed in gamma-rays. For our analysis, we use the unbinned maximum likelihood method to look for a statistically significant excess. We do not find any such spatial association between any of the red dwarfs and IceCube-detected neutrinos. Therefore, we conclude that none of the gamma-ray bright red dwarfs contribute to the diffuse neutrino flux measured by IceCube.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"47 ","pages":"Article 100366"},"PeriodicalIF":10.2,"publicationDate":"2025-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143620090","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":"Deciphering the multi-wavelength flares of the most distant very high-energy (>100 GeV) γ-ray emitting blazar","authors":"P.N. Naseef Mohammed ,&nbsp;T. Aminabi ,&nbsp;C. Baheeja ,&nbsp;S. Sahayanathan ,&nbsp;Vaidehi S. Paliya ,&nbsp;C.D. Ravikumar","doi":"10.1016/j.jheap.2025.100365","DOIUrl":"10.1016/j.jheap.2025.100365","url":null,"abstract":"<div><div>This study analyzes the multi-wavelength flaring activity of the distant flat spectrum radio quasar (FSRQ) OP 313 (z=0.997) during November 2023 to March 2024, using data from Fermi-Large Area Telescope, Swift X-ray Telescope, and Ultraviolet and Optical Telescope. The analysis highlights two significant very high energy (VHE) detection epochs and GeV gamma-ray flaring episodes, providing insight into jet emission processes and radiative mechanisms. We study the evolution of broadband spectral energy distribution (SED) and identify, for the first time, that the source displays three different characteristics in its synchrotron peaks within a short span of four months, which is rather uncommon in FSRQs. Modeling of the multi-wavelength SED with a one-zone leptonic radiative processes attributes the emissions to synchrotron radiation, Synchrotron Self-Compton (SSC), and External Compton (EC) mechanisms, with torus photons as the primary source for EC processes. The results suggest that the gamma-ray emitting region lies outside the broad-line region but within the dusty torus. Furthermore, we find that the radiated power is significantly smaller than the total jet power, suggesting that most of the bulk energy remains within the jet even after passing through the blazar emission zone.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"47 ","pages":"Article 100365"},"PeriodicalIF":10.2,"publicationDate":"2025-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143620091","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":"Measuring the intensity of the interstellar radiation field with ultra-high energy γ ray spectra","authors":"Nayantara Gupta","doi":"10.1016/j.jheap.2025.100364","DOIUrl":"10.1016/j.jheap.2025.100364","url":null,"abstract":"<div><div>Our understanding of the intensity distribution of the interstellar radiation background is based on the observational data from IRAS, COBE-FIRAS and Planck. The intensity of this radiation field increases rapidly towards the Galactic plane and is the highest near the Galactic centre due to the high density of stars and dust. However, a precise determination of the variations of this radiation field with spatial and angular coordinates is not feasible observationally. We explore how future studies of gamma-ray spectra from numerous ultra-high-energy gamma-ray sources can indirectly probe variations in the interstellar radiation field's intensity across different distances from the Galactic centre and across Galactic latitudes and longitudes. This study is crucial for making self-consistent predictions of high energy gamma-ray fluxes from Galactic sources detected by observatories like LHAASO, Tibet AS_<em>γ</em> and the next-generation gamma-ray telescopes.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"47 ","pages":"Article 100364"},"PeriodicalIF":10.2,"publicationDate":"2025-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143610620","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":"Insights into the long-term behavior of the optical polarization from the blazar 1ES 1959+650","authors":"K.K. Singh ,&nbsp;A. Singh ,&nbsp;A. Tolamatti ,&nbsp;P.J. Meintjes ,&nbsp;K.K. Yadav","doi":"10.1016/j.jheap.2025.100361","DOIUrl":"10.1016/j.jheap.2025.100361","url":null,"abstract":"<div><div>A high degree of linear polarization measured in the optical emission is an important observational feature of blazars. It provides strong evidence of the presence of relativistic particles and magnetic field ordering in the non-thermal emission regions of blazars owing to the synchrotron nature of low energy radiation. Thus, the polarization studies of blazars are emerging as a promising approach to probe the particle acceleration and the physical processes involved in their broadband emission. In this work, we investigate the behavior of the optical polarization of the blazar 1ES 1959+650 measured over a decade using the spectropolarimetry (SPOL) at the Steward Observatory. We use measurements of the degree of linear polarization and angle of polarization in the wavelength range 500 - 700 nm available during the period October 1, 2008 and June 30, 2018 (MJD 54739 - 58299) from the SPOL observations. Near simultaneous photometry data in the R and V bands are also used to study the optical emission from the source. The maximum degree of linear polarization, measured as ∼ 8.5%, is significantly larger than the long term average value of ∼ 4.6%. Analysis of the light curves indicates that the optical emission from the blazar 1ES 1959+650 is highly variable and variability in the degree of linear polarization can be quantified by a fractional variability amplitude of ∼ 39% over the period of about ten years. Long term optical emission in the R and V bands is very weakly anti-correlated with the degree of linear polarization. Modeling of the polarization due to the synchrotron emission suggests that the observed degree of linear polarization can be broadly reproduced by a power law distribution of relativistic electrons gyrating in a spherical emission region permeated with chaotic and ordered magnetic fields. Variation in the measured degree of polarization may be attributed to the interplay between the two magnetic field components in the emission region. The effect of stellar emission from the host galaxy of the blazar 1ES 1959+650 on the degree of synchrotron polarization originating from the jet is also discussed.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"47 ","pages":"Article 100361"},"PeriodicalIF":10.2,"publicationDate":"2025-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143552612","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":"Long pulse by short central engine: Prompt emission from expanding dissipation rings in the jet front of gamma-ray bursts","authors":"Shu-Xu Yi ,&nbsp;Emre Seyit Yorgancioglu ,&nbsp;S.-L. Xiong ,&nbsp;S.-N. Zhang","doi":"10.1016/j.jheap.2025.100359","DOIUrl":"10.1016/j.jheap.2025.100359","url":null,"abstract":"<div><div>Recent observations have challenged the long-held opinion that the duration of gamma-ray burst (GRB) prompt emission is determined by the activity epochs of the central engine. Specifically, the observations of GRB 230307A have revealed a different scenario in which the duration of the prompt emission is predominantly governed by the energy dissipation process following a brief initial energy injection from the central engine. In this paper, we explore a mechanism where the energy injection from the central engine initially causes turbulence in a small region and radiates locally. This turbulence then propagates to more distant regions and radiates. Consequently, the emission regions form concentric rings that extend outward. Using an idealized toy model, we show that such a mechanism, initiated by a pulsed energy injection, can produce a prompt emission light curve resembling a single broad pulse exhibiting the typical softer-wider/softer-later feature. Under some parameters, the main characteristics of the GRB 230307A spectra and light curves can be reproduced by the toy model.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"47 ","pages":"Article 100359"},"PeriodicalIF":10.2,"publicationDate":"2025-02-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143552583","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}