Journal of High Energy Astrophysics最新文献

{"title":"The properties of the Galactic hard X-ray and soft γ-ray background based on 20 years of INTEGRAL/IBIS observations","authors":"Roman Krivonos,&nbsp;Ekaterina Shtykovskaya,&nbsp;Sergey Sazonov","doi":"10.1016/j.jheap.2024.11.014","DOIUrl":"10.1016/j.jheap.2024.11.014","url":null,"abstract":"<div><div>We present results of a study of the Galactic hard X-ray and soft <em>γ</em>-ray background emission performed with the <em>IBIS</em> telescope aboard the <em>INTEGRAL</em> observatory using data obtained over more than 20 years of operations. The study of the Galactic background at energies between 10 keV and a few MeV is problematic due to the contribution of point sources, high instrumental background and large-scale extent of the emission, which leads to the need of utilizing complex model-dependent methods. Using the unique properties of the <em>IBIS</em> coded-mask telescope, we developed a model-independent approach to study diffuse continuum emission near the Galactic plane in the 25−60, 60−80, and 80−200 keV bands. The comparison of the 25−60 keV longitude profile with the near infrared intensity shows excellent agreement, confirming the stellar origin of the Galactic Ridge X-ray Emission (GRXE). The Galactic X-ray background is significantly detected from the direction of the Galactic bulge up to 200 keV. We built broad-band spectra of the Galactic background in three large regions, the Galactic bulge and two spiral arms at <span><math><mi>l</mi><mo>≈</mo><mo>±</mo><msup><mrow><mn>20</mn></mrow><mrow><mo>∘</mo></mrow></msup></math></span>. The spectral analysis reveals two distinct components with a minimum at about 80 keV. The low-energy (≲60 keV) component, associated with the GRXE, is consistent with a one-dimensional accretion flow model of intermediate polars with an average white dwarf mass of about 0.7 <span><math><msub><mrow><mi>M</mi></mrow><mrow><mo>⊙</mo></mrow></msub></math></span>. The high-energy part of the spectrum, dominating above ∼60 keV and attributed to the <em>γ</em>-ray background, is consistent with a power-law model with photon index <span><math><mi>Γ</mi><mo>=</mo><mn>1.55</mn></math></span>. The total 30−80 keV flux budget of <span><math><mn>1.5</mn><mo>×</mo><msup><mrow><mn>10</mn></mrow><mrow><mo>−</mo><mn>9</mn></mrow></msup></math></span> erg s⁻¹ cm⁻² observed within the effective <em>IBIS</em> field of view (≈286 deg²) in the Galactic bulge region, consists of 2/3 of GRXE and 1/3 of <em>γ</em>-ray background. Finally, we provide the Python code of the <em>IBIS</em>/<em>ISGRI</em> background model, which can be used to measure the X-ray intensity of the Galactic background in different parts of the Milky Way.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"45 ","pages":"Pages 96-104"},"PeriodicalIF":10.2,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142701153","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 rotating quantum-corrected black holes: Insights and constraints from EHT observations of M87* and Sgr A*","authors":"Amnish Vachher ,&nbsp;Sushant G. Ghosh","doi":"10.1016/j.jheap.2024.11.012","DOIUrl":"10.1016/j.jheap.2024.11.012","url":null,"abstract":"&lt;div&gt;&lt;div&gt;We study gravitational lensing in the strong-field limit using the rotating quantum-corrected black hole (RQCBH) with an additional parameter &lt;em&gt;α&lt;/em&gt; besides mass &lt;em&gt;M&lt;/em&gt; and spin parameter &lt;em&gt;a&lt;/em&gt;. We discover a decrease in the deflection angle &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;α&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;D&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt;, the photon sphere radius &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;x&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;p&lt;/mi&gt;&lt;mi&gt;s&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt;, and the angular position &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;mo&gt;∞&lt;/mo&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt;. The flux ratio of the first image to all subsequent images, &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;r&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;m&lt;/mi&gt;&lt;mi&gt;a&lt;/mi&gt;&lt;mi&gt;g&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt;, decreases rapidly as &lt;em&gt;α&lt;/em&gt; increases. We compare RQCBH observables with those of Kerr black holes, using Sgr A* and M87* as lenses to observe the effect of the quantum-corrected parameter &lt;em&gt;α&lt;/em&gt;. For Sgr A*, the angular position &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;mo&gt;∞&lt;/mo&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt; in &lt;span&gt;&lt;math&gt;&lt;mo&gt;∈&lt;/mo&gt;&lt;mspace&gt;&lt;/mspace&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mn&gt;14.8&lt;/mn&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mn&gt;26.3&lt;/mn&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;mspace&gt;&lt;/mspace&gt;&lt;mi&gt;μ&lt;/mi&gt;&lt;mi&gt;a&lt;/mi&gt;&lt;mi&gt;s&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt;, while for M87* &lt;span&gt;&lt;math&gt;&lt;mo&gt;∈&lt;/mo&gt;&lt;mspace&gt;&lt;/mspace&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mn&gt;11.12&lt;/mn&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mn&gt;19.78&lt;/mn&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;mspace&gt;&lt;/mspace&gt;&lt;mi&gt;μ&lt;/mi&gt;&lt;mi&gt;a&lt;/mi&gt;&lt;mi&gt;s&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt;. The angular separation &lt;em&gt;s&lt;/em&gt;, for supermassive black holes (SMBHs) SgrA* and M87*, differs significantly, with values ranging &lt;span&gt;&lt;math&gt;&lt;mo&gt;∈&lt;/mo&gt;&lt;mspace&gt;&lt;/mspace&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mn&gt;0.033&lt;/mn&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mn&gt;0.79&lt;/mn&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;mspace&gt;&lt;/mspace&gt;&lt;mi&gt;μ&lt;/mi&gt;&lt;mi&gt;a&lt;/mi&gt;&lt;mi&gt;s&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt; for Sgr A* and &lt;span&gt;&lt;math&gt;&lt;mo&gt;∈&lt;/mo&gt;&lt;mspace&gt;&lt;/mspace&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mn&gt;0.033&lt;/mn&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mn&gt;0.59&lt;/mn&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;mspace&gt;&lt;/mspace&gt;&lt;mi&gt;μ&lt;/mi&gt;&lt;mi&gt;a&lt;/mi&gt;&lt;mi&gt;s&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt; for M87*. The deviations of the lensing observables &lt;span&gt;&lt;math&gt;&lt;mo&gt;|&lt;/mo&gt;&lt;mi&gt;Δ&lt;/mi&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;θ&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mo&gt;∞&lt;/mo&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mo&gt;|&lt;/mo&gt;&lt;/math&gt;&lt;/span&gt; and &lt;span&gt;&lt;math&gt;&lt;mo&gt;|&lt;/mo&gt;&lt;mi&gt;Δ&lt;/mi&gt;&lt;mi&gt;s&lt;/mi&gt;&lt;mo&gt;|&lt;/mo&gt;&lt;/math&gt;&lt;/span&gt; for RQCBH (&lt;span&gt;&lt;math&gt;&lt;mi&gt;a&lt;/mi&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;0.8&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;0.4&lt;/mn&gt;&lt;/math&gt;&lt;/span&gt;) from Kerr black holes can reach up to &lt;span&gt;&lt;math&gt;&lt;mn&gt;1.6&lt;/mn&gt;&lt;mspace&gt;&lt;/mspace&gt;&lt;mi&gt;μ&lt;/mi&gt;&lt;mi&gt;a&lt;/mi&gt;&lt;mi&gt;s&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt; and &lt;span&gt;&lt;math&gt;&lt;mn&gt;0.41&lt;/mn&gt;&lt;mspace&gt;&lt;/mspace&gt;&lt;mi&gt;μ&lt;/mi&gt;&lt;mi&gt;a&lt;/mi&gt;&lt;mi&gt;s&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt; for Sgr A*, and &lt;span&gt;&lt;math&gt;&lt;mn&gt;1.2&lt;/mn&gt;&lt;mspace&gt;&lt;/mspace&gt;&lt;mi&gt;μ&lt;/mi&gt;&lt;mi&gt;a&lt;/mi&gt;&lt;mi&gt;s&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt; and &lt;span&gt;&lt;math&gt;&lt;mn&gt;0.31&lt;/mn&gt;&lt;mspace&gt;&lt;/mspace&gt;&lt;mi&gt;μ&lt;/mi&gt;&lt;mi&gt;a&lt;/mi&gt;&lt;mi&gt;s&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt; for M87*. The relative magnitude &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;r&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;m&lt;/mi&gt;&lt;mi&gt;a&lt;/mi&gt;&lt;mi&gt;g&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt; &lt;span&gt;&lt;math&gt;&lt;mo&gt;∈&lt;/mo&gt;&lt;mspace&gt;&lt;/mspace&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mn&gt;1.81&lt;/mn&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mn&gt;6.82&lt;/mn&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;mspace&gt;&lt;/mspace&gt;&lt;mi&gt;μ&lt;/mi&gt;&lt;mi&gt;a&lt;/mi&gt;&lt;mi&gt;s&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt;. We also compared the time delays between the relativistic images in ","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"45 ","pages":"Pages 75-86"},"PeriodicalIF":10.2,"publicationDate":"2024-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142701245","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":"Revisiting thermodynamic topology of Hawking-Page and Davies type phase transitions","authors":"Bidyut Hazarika ,&nbsp;Naba Jyoti Gogoi ,&nbsp;Prabwal Phukon","doi":"10.1016/j.jheap.2024.11.013","DOIUrl":"10.1016/j.jheap.2024.11.013","url":null,"abstract":"<div><div>In this work, we propose a common vector field to study the thermodynamic topology of the Davies type and Hawking-Page phase transitions. Existing literature has shown that studying these two types of phase transitions typically requires defining two separate vector fields. In our approach, we adopt Duan's <em>ϕ</em>-mapping topological current theory to define a novel vector field, denoted as <em>ϕ</em>, whose critical points exactly correspond to the Davies point and the Hawking-Page phase transition point. More importantly, we can differentiate between these two points by their topological charge. While, the topological charge for the critical point corresponding to the Davies-type phase transition is found to be −1, the same for the Hawking-Page phase transition point, it is +1. Although our analysis is applicable to all black hole systems where both types of phase transitions are found, we illustrate it using three simple systems as examples: the Schwarzschild AdS black hole, the Reissner-Nordström AdS black hole in the grand canonical ensemble, and finally the Kerr AdS black holes in the grand canonical ensemble. It is well-known that these black holes exhibit both Davies and Hawking-Page phase transitions. With our proposed vector <em>ϕ</em>, the critical points obtained for these three systems exactly match the Davies-type and Hawking-Page phase transition points, and the associated topological charges are found to be −1 for the Davies point and +1 for the Hawking-Page phase transition point.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"45 ","pages":"Pages 87-95"},"PeriodicalIF":10.2,"publicationDate":"2024-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142701152","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":"Influence of minimal gravitational decoupling and pseudo isothermal dark matter halo on mass-radius relation and stability of anisotropic compact stars in f(R,T)–gravity","authors":"S.K. Maurya ,&nbsp;A. Errehymy ,&nbsp;B. Dayanandan ,&nbsp;O. Donmez ,&nbsp;K. Myrzakulov ,&nbsp;Kottakkaran Sooppy Nisar ,&nbsp;M. Mahmoud","doi":"10.1016/j.jheap.2024.11.011","DOIUrl":"10.1016/j.jheap.2024.11.011","url":null,"abstract":"<div><div>We have provided a new exact solution for anisotropic compact stars to the field equations of <span><math><mi>f</mi><mo>(</mo><mi>R</mi><mo>,</mo><mi>T</mi><mo>)</mo></math></span>-gravity via a decoupling technique, with the assumption of a linear <span><math><mi>f</mi><mo>(</mo><mi>T</mi><mo>)</mo></math></span> function and the modified Durgapal-Fuloria metric ansatz. By deforming the radial component of the metric and introducing Pseudo-Isothermal (PI) dark matter (DM) as a new source to the anisotropic seed solution in the process of minimally gravitational decoupling, we have obtained a non-singular solution that meets all physical criteria related to effective density, effective pressure, effective anisotropy, and energy conditions. The present system satisfies the modified Tolman-Oppenheimer-Volkoff equation and achieves stable equilibrium, fulfilling stability criteria such as the adiabatic condition, Herrera cracking concept, and Harrison-Zeldovich-Novikov condition. The influence of minimally gravitational decoupling on the characteristics of the system has been illustrated graphically by varying the decoupling constant (<em>γ</em>). The mass-radius relations are linked to observational constraints and examined for anisotropic stellar systems with and without the effect of minimally gravitational decoupling in both general relativity (GR) and <span><math><mi>f</mi><mo>(</mo><mi>R</mi><mo>,</mo><mi>T</mi><mo>)</mo></math></span>-gravity. We found that increasing values of the <span><math><mi>f</mi><mo>(</mo><mi>R</mi><mo>,</mo><mi>T</mi><mo>)</mo></math></span>-gravity parameter (<em>χ</em>) and <em>γ</em> reduce the maximum allowable mass of the star. Therefore, increasing the effects of minimally gravitational decoupling and the PI-DM content, subject to the Durgapal-Fuloria metric potential ansatz, cannot support highly compact and supermassive astrophysical objects.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"45 ","pages":"Pages 46-61"},"PeriodicalIF":10.2,"publicationDate":"2024-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142701244","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":"Role of the complexity factor and Karmarkar condition in constructing new wormhole models in dRGT gravity","authors":"Jitendra Kumar ,&nbsp;S.K. Maurya ,&nbsp;Sweeti Kiroriwal ,&nbsp;Abdelghani Errehymy ,&nbsp;Orhan Donmez ,&nbsp;Kairat Myrzakulov","doi":"10.1016/j.jheap.2024.11.009","DOIUrl":"10.1016/j.jheap.2024.11.009","url":null,"abstract":"<div><div>This study delves into the distinctive characteristics of wormhole models in the context of de Rham-Gabadadze-Tolley (dRGT) massive gravity, providing insights into their theoretical behavior and stability. We use a null zero complexity factor to find the wormhole shape function for Model I. Additionally, we solve analytically the modified field equations describing wormhole for a given choice of logarithmic redshift function, exploiting the Karmarkar condition for embedding class one metrics for Model II. To achieve this, we analyze the wormhole geometry in a static spherical spacetime with an anisotropic matter configuration. The study investigates a number of parameters, including density, energy conditions, equation of state parameter, adiabatic sound velocity, and equilibrium condition. The solution shows a traversable wormhole that violates the null energy criterion and equilibrium state for certain ranges of free parameters. We employ adiabatic sound velocity analysis to concentrate on the stability of the wormhole. Furthermore, by using the equation of state parameter (<em>ω</em>), we conclude that both models end up in the phantom dark energy region. Finally, our findings highlight distinct photon deflection behaviors in dRTG massive gravity, with Model II showing negative angles indicative of repulsive gravity, while Model I exhibits positive angles, underscoring significant differences in gravitational dynamics.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"45 ","pages":"Pages 32-45"},"PeriodicalIF":10.2,"publicationDate":"2024-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142701242","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":"Thermal chemistry of Anti-de-Sitter black holes in Kalb-Ramond gravity","authors":"Allah Ditta ,&nbsp;Faisal Javed ,&nbsp;Abdelmalek Bouzenada ,&nbsp;G. Mustafa ,&nbsp;Asif Mahmood ,&nbsp;Farruh Atamurotov ,&nbsp;Vokhid Khamidov","doi":"10.1016/j.jheap.2024.11.010","DOIUrl":"10.1016/j.jheap.2024.11.010","url":null,"abstract":"<div><div>In this paper, we investigate the thermodynamic properties and emission energy of Anti-de-Sitter (AdS) black holes within the framework of Kalb-Ramond gravity. By analyzing the modified Einstein equations with the inclusion of the antisymmetric Kalb-Ramond tensor field, we explore the changes in key thermodynamic quantities such as temperature, entropy, and specific heat, alongside the emission energy spectrum associated with Hawking radiation. The study reveals novel thermal behaviors and energy emission patterns compared to standard AdS black holes, particularly highlighting the influence of the Kalb-Ramond field on black hole stability and phase transitions. Furthermore, we examine the role of the Kalb-Ramond field in modifying the emission energy. Our findings provide deeper insights into black hole thermodynamics, the emission process, and the broader role of antisymmetric fields in gravitational physics. Different paths for test particles near black holes are determined by their distance from the innermost stable circular orbit, which plays a crucial role in this study. The unique behavior of particles impacted by mass and rotational momentum is highlighted by the fact that particles within the innermost stable circular orbits tend to converge toward the singularity, but particles outside tend to diverge toward infinity.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"45 ","pages":"Pages 62-74"},"PeriodicalIF":10.2,"publicationDate":"2024-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142701243","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":"From low- to high-frequency QPOs around the non-rotating hairy Horndeski black hole: Microquasar GRS 1915+105","authors":"O. Donmez","doi":"10.1016/j.jheap.2024.11.002","DOIUrl":"10.1016/j.jheap.2024.11.002","url":null,"abstract":"<div><div>Research on the Horndeski black hole, associated with the scalar hairy parameter, offers insights into enigmatic cosmic phenomena such as dark matter. Additionally, the numerical study of the GRS 1915+105 source, which exhibits continuous variability in X-ray observations, along with its physical properties and mechanisms behind Quasi-periodic oscillations (QPOs) frequencies, can contribute to observational studies. Motivated by this, we examine the variations in physical mechanisms around the non-rotating Horndeski black hole with Bondi-Hoyle-Lyttleton (BHL) accretion related to the scalar hair parameter and the resulting QPO frequencies. Numerical simulations have shown the formation of a shock cone around the black hole. With a decrease in the scalar hair parameter, the shock cone opening angle narrows due to the influence of the scalar field potential, and the stagnation point within the cone moves closer to the black hole horizon. With the changing scalar hair parameter, the simultaneous formation of the shock cone and bow shock is observed. Due to the intense increase in scalar potential, both the shock cone and bow shock disappeared, and a cavity surrounding the black hole forms in the area where the shock cone was. Additionally, QPO oscillations induced by the physical mechanisms observed in relation to the hair parameter are revealed through numerical simulations. A broad range of QPO frequencies is observed, from low to high frequencies, with resonance states like 3:2 occurring. The QPO frequencies determined numerically are compared with the observational results of the GRS 1915+105 source, demonstrating a match between the observations and numerical findings. From this, it is concluded that the shock cone, bow shock, and cavity are suitable physical mechanisms for generating QPOs for the GRS 1915+105 source. Lastly, we define the potential range of the spin parameter for the GRS 1915+105 source based on the agreement between observational and numerical results. It has also been found that for most of the QPOs obtained from numerical calculations to be consistent with observations, <span><math><mi>h</mi><mo>/</mo><mi>M</mi></math></span> should be greater than −0.5.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"45 ","pages":"Pages 1-18"},"PeriodicalIF":10.2,"publicationDate":"2024-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142655453","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 new method for studying the blazar variability on the shortest time scales and its application to S5 1803+784","authors":"M.S. Butuzova,&nbsp;V.A. Guseva,&nbsp;M.A. Gorbachev,&nbsp;A.S. Krivenko,&nbsp;S.V. Nazarov","doi":"10.1016/j.jheap.2024.11.008","DOIUrl":"10.1016/j.jheap.2024.11.008","url":null,"abstract":"<div><div>We propose a new method for investigating the evolution of the properties of the blazar brightness variability on timescales from a few hours to a few days. Its essence lies in detecting sequentially located time intervals along the entire light curve, within which it is possible to determine the characteristic time of variability using the structure function. We applied this method to uniform data series lasting several days provided by the TESS mission for blazar S5 1803+784. Then, we analyzed the found time parameters of variability coupled with the data of B-, V-, R-, and I-photometric observations. A correlation was found between the amplitude and the characteristic time of variability. The relation of these values with the spectral index of radiation has not been revealed. We conclude that the variability on a short time scale is formed due to the different Doppler factors for having different volume parts of the optical emitting region. At the same time, the radiation spectrum deflects slightly from the power-law.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"45 ","pages":"Pages 19-31"},"PeriodicalIF":10.2,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142655425","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":"First few overtones probe the event horizon geometry","authors":"R.A. Konoplya ,&nbsp;A. Zhidenko","doi":"10.1016/j.jheap.2024.10.015","DOIUrl":"10.1016/j.jheap.2024.10.015","url":null,"abstract":"<div><div>It is broadly believed that quasinormal modes cannot tell the black-hole near-horizon geometry, because usually the low-lying modes are determined by the scattering of perturbations around the peak of the effective potential. Using the general parametrization of the black-hole spacetimes respecting the generic post-Newtonian asymptotic, we will show that tiny modifications of the Schwarzschild/Kerr geometry in a relatively small region near the event horizon lead to almost the same Schwarzschild/Kerr fundamental mode, but totally different first few overtones. Having in mind that the first several overtones affect the quasinormal ringing at its early and intermediate stage (<span><span>Giesler et al., 2019</span></span>), we argue that the near-horizon geometry could in principle be studied via the first few overtones of the quasinormal spectrum, which is important because corrections to the Einstein theory must modify precisely the near-horizon geometry, keeping the known weak field regime.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"44 ","pages":"Pages 419-426"},"PeriodicalIF":10.2,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142586430","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":"Probing broadband spectral energy distribution and variability of Mrk 501 in the low flux state","authors":"Javaid Tantry ,&nbsp;Zahir Shah ,&nbsp;Ranjeev Misra ,&nbsp;Naseer Iqbal ,&nbsp;Sikandar Akbar","doi":"10.1016/j.jheap.2024.10.014","DOIUrl":"10.1016/j.jheap.2024.10.014","url":null,"abstract":"<div><div>We conducted a multi-wavelength analysis of the blazar Mrk<!--> <!-->501, utilizing observations from <em>Astro</em>Sat (SXT, LAXPC), <em>Swift-UVOT</em>, and <em>Fermi-LAT</em> during the period August 15, 2016 to March 27, 2022. The resulting multi-wavelength light curve revealed relatively low activity of the source across the electromagnetic spectrum. Notably, logparabola and broken power-law models provided a better fit to the joint X-ray spectra from <em>Astro</em>Sat-SXT/LAXPC instruments compared to the power-law model. During the low activity state, the source showed the characteristic “harder when brighter” trend at the X-ray energies. To gain insights into underlying physical processes responsible for the broadband emission, we performed a detailed broadband spectral analysis using the convolved one-zone leptonic model with different forms of particle distributions such as logparabola (LP), broken power-law (BPL), power-law model with maximum energy (<span><math><msub><mrow><mi>ξ</mi></mrow><mrow><mi>m</mi><mi>a</mi><mi>x</mi></mrow></msub></math></span>), and energy-dependent acceleration (EDA) models. Our analysis revealed similar reduced-<span><math><msup><mrow><mi>χ</mi></mrow><mrow><mn>2</mn></mrow></msup></math></span> values for the four particle distributions. The LP and EDA models exhibited the lowest jet powers. The correlation analyses conducted for the LP and BPL models revealed that there is a positive correlation between jet power and bulk Lorentz factor. Specifically, in the LP model, jet power proved independent of <span><math><msub><mrow><mi>γ</mi></mrow><mrow><mi>m</mi><mi>i</mi><mi>n</mi></mrow></msub></math></span>, whereas in the broken power-law model, jet power decreased with an increase in <span><math><msub><mrow><mi>γ</mi></mrow><mrow><mi>m</mi><mi>i</mi><mi>n</mi></mrow></msub></math></span>. The jet power in the LP/EDA particle distribution is nearly 10 percent of the Eddington luminosity of a 10⁷ M_⊙ black hole. This result suggests that the jet could potentially be fueled by accretion processes.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"44 ","pages":"Pages 393-409"},"PeriodicalIF":10.2,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142578482","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}