Journal of High Energy Astrophysics最新文献

{"title":"Power law cosmology in Gauss-Bonnet gravity with pragmatic analysis","authors":"Rita Rani ,&nbsp;Shaily ,&nbsp;G.K. Goswami ,&nbsp;J.K. Singh","doi":"10.1016/j.jheap.2024.11.021","DOIUrl":"10.1016/j.jheap.2024.11.021","url":null,"abstract":"<div><div>In this study, we present an approach <span><math><mi>f</mi><mo>(</mo><mi>R</mi><mo>,</mo><mi>G</mi><mo>)</mo></math></span> gravity incorporating power law in <em>G</em>. To study the cosmic evolution of the universe given by the reconstruction of the Hubble parameter given by <span><math><mi>E</mi><mo>(</mo><mi>z</mi><mo>)</mo><mo>=</mo><msup><mrow><mo>(</mo><mn>1</mn><mo>+</mo><mfrac><mrow><mi>z</mi><mo>(</mo><mi>α</mi><mo>+</mo><msup><mrow><mo>(</mo><mn>1</mn><mo>+</mo><mi>z</mi><mo>)</mo></mrow><mrow><mi>β</mi></mrow></msup><mo>)</mo></mrow><mrow><mn>2</mn><mi>β</mi><mo>+</mo><mn>1</mn></mrow></mfrac><mo>)</mo></mrow><mrow><mfrac><mrow><mn>3</mn></mrow><mrow><mn>2</mn><mi>β</mi></mrow></mfrac></mrow></msup></math></span>. Subsequently, we use various recent observational datasets of OHD, Pantheon, and BAO to estimate the model parameters <span><math><msub><mrow><mi>H</mi></mrow><mrow><mn>0</mn></mrow></msub><mo>,</mo><mspace></mspace><mi>α</mi></math></span>, and <em>β</em> applying the Markov Chain Monte Carlo (MCMC) technique in the emcee package to establish the validity of the model. In our findings, we observe that our model shows consistency with standard ΛCDM, transits from deceleration to acceleration, and enters the quintessence region in late times. The cosmological model satisfies necessary energy constraints, simultaneously violating the strong energy condition (SEC), indicating a repulsive nature and consistent with accelerated expansion. The cosmic evolution of the Hawking temperature and the total entropy for the various observational datasets also show the validity of the model. Thus, our established model demonstrates sufficient potential for explicitly describing cosmological models.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"45 ","pages":"Pages 168-180"},"PeriodicalIF":10.2,"publicationDate":"2024-12-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143098610","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":"Quasinormal modes and greybody bounds of black holes endowed with modified Chaplygin gas","authors":"Y. Sekhmani ,&nbsp;D.J. Gogoi ,&nbsp;S.K. Maurya ,&nbsp;K. Boshkayev ,&nbsp;M.K. Jasim","doi":"10.1016/j.jheap.2024.11.020","DOIUrl":"10.1016/j.jheap.2024.11.020","url":null,"abstract":"<div><div>This paper investigates the quasinormal modes and greybody factors of black holes with modified Chaplygin gas. Applying the WKB approximation method, we analyze the impact of model parameters <em>A</em>, <em>β</em>, <em>B</em>, and <em>γ</em> on the oscillation frequency and damping rate of gravitational waves. Parameters <em>A</em> and <em>β</em> initially decrease these measures before a gradual increase, while <em>B</em> significantly influences them with a distinct critical point behaviour, and <em>γ</em> causes a gradual increase. Additionally, we explore greybody factor bounds analytically, revealing that smaller multipole moments <em>l</em> yield higher bounds, increasing <em>A</em> decreases bounds slowly, <em>B</em> significantly increases them, <em>β</em> decreases them, and <em>γ</em> has a minimal impact. These findings enhance our insight of the dynamics of black holes with modified Chaplygin gas, particularly their quasinormal modes and greybody factors.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"45 ","pages":"Pages 200-213"},"PeriodicalIF":10.2,"publicationDate":"2024-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143164035","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":"Effect of turbulence on blazar variability - II: Stochastic variability within leptonic scenario","authors":"Bitan Ghosal ,&nbsp;Nilay Bhatt ,&nbsp;Subir Bhattacharyya ,&nbsp;Kuldeep Kumar Yadav","doi":"10.1016/j.jheap.2024.11.019","DOIUrl":"10.1016/j.jheap.2024.11.019","url":null,"abstract":"<div><div>Understanding the origin of the long-term stochastic variability of blazars in different wavebands is a decade-long problem. In this work, we investigate the stochastic variability of blazar emission within the framework of a time-dependent one-zone leptonic model. This model considers the acceleration of the relativistic electrons present in the blazar jet by both the Fermi first order and second order acceleration process, along with radiative energy loss of the same electrons and diffusive escape of those electrons from the acceleration/emission zone. The effect of second order Fermi acceleration is incorporated in the present model through momentum diffusion coefficient considering random scattering of the relativistic electrons by magneto-hydrodynamic (MHD) turbulence. We simulate the variability in the multi-wavelength photon light curves by introducing stochastic variation in the electron injection. Then estimated the power spectral density, probability density function and rms-flux relation to quantify the variability. Here, we show that for different types of stochastic injection process, the nature of the variability changes. The variability properties also depend on the nature of the MHD turbulence present in the system.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"45 ","pages":"Pages 146-159"},"PeriodicalIF":10.2,"publicationDate":"2024-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143098609","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":"Cooling of neutron stars in soft X-ray transients with realistic crust composition","authors":"A.Y. Potekhin ,&nbsp;A.I. Chugunov ,&nbsp;N.N. Shchechilin ,&nbsp;M.E. Gusakov","doi":"10.1016/j.jheap.2024.11.017","DOIUrl":"10.1016/j.jheap.2024.11.017","url":null,"abstract":"<div><div>Thermal radiation of neutron stars in soft X-ray transients (SXTs) in a quiescent state is believed to be powered by the heat deposited in the stellar crust due to nuclear reactions during accretion. Confronting observations of this radiation with simulations helps to verify theoretical models of the dense matter in neutron stars. We simulate the thermal evolution of the SXTs with theoretical models of the equation of state and composition of the accreted crust. The new family of such models were recently developed within a thermodynamically consistent approach by modeling the nuclear evolution of an accreted matter as it sinks toward the stellar center, starting from representative thermonuclear ash compositions. The crust cooling curves computed with the traditional and modern theory are compared with observations of SXTs MXB 1659−29 and IGR J17480−2446. We show that the new and traditional models of the accreted neutron star crusts are similar in their capability to explain the thermal evolution of neutron stars in SXTs. Both kinds of models require inclusion of additional ingredients not supplied by the current theory, such as the shallow heating and variation of thermal conductivity, to fit observations.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"45 ","pages":"Pages 116-124"},"PeriodicalIF":10.2,"publicationDate":"2024-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142720452","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 the warped vacuum geometry around a Kerr black hole by quasi-periodic oscillations","authors":"Ali Vahedi ,&nbsp;M. Hossein Hesamolhokama ,&nbsp;Alireza Allahyari ,&nbsp;Jafar Khodagholizadeh","doi":"10.1016/j.jheap.2024.11.015","DOIUrl":"10.1016/j.jheap.2024.11.015","url":null,"abstract":"<div><div>We investigate quasi-periodic oscillations (QPOs) in the context of a new rotating black hole solution that incorporates a cosmological constant. Recent work by the authors in <span><span>Ovalle (2022)</span></span> interpreted the cosmological constant, denoted as Λ, as a form of vacuum energy and employed a gravitational decoupling approach to derive an extended Kerr–de Sitter black hole solution, which is geometrically richer than the classical case. In this study, we derive the expressions for timelike circular geodesics within this solution and, using a relativistic precision model, calculate the corresponding frequencies of the QPOs.</div><div>To constrain our model, we apply Bayesian formalism, utilizing data from three well-known microquasars: GRO 1655-40, XTE 1550-564, and GRS 1915+105. Our analysis reveals that Λ is degenerate and correlated with other parameters. Finally, we perform a Bayesian model comparison with the Kerr metric and find that the Kerr metric is favored among the models considered.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"45 ","pages":"Pages 125-134"},"PeriodicalIF":10.2,"publicationDate":"2024-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142747973","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":"Observational analysis of gravitational baryogenesis constraints in Einstein-Æther gravity","authors":"Abdul Malik Sultan ,&nbsp;Alishba Mushtaq ,&nbsp;Dean Chou ,&nbsp;Hamood Ur Rehman ,&nbsp;Hameed Ashraf ,&nbsp;Aziz Ullah Awan","doi":"10.1016/j.jheap.2024.11.018","DOIUrl":"10.1016/j.jheap.2024.11.018","url":null,"abstract":"<div><div>In this article, we investigate the mystery of matter dominance over antimatter through gravitational baryogenesis in context of Einstein-Æther gravity. This study aims to focus on the phenomenon of baryon asymmetry produced in the universe a while after the Big Bang. The supremacy of matter over antimatter is quantified by <span><math><mfrac><mrow><msub><mrow><mi>η</mi></mrow><mrow><mi>B</mi></mrow></msub></mrow><mrow><mi>s</mi></mrow></mfrac><mo>=</mo><mfrac><mrow><msub><mrow><mi>η</mi></mrow><mrow><mi>B</mi></mrow></msub><mo>−</mo><msub><mrow><mi>η</mi></mrow><mrow><mover><mrow><mi>B</mi></mrow><mrow><mo>¯</mo></mrow></mover></mrow></msub></mrow><mrow><mi>s</mi></mrow></mfrac></math></span> where <em>s</em> is entropy of the universe and <span><math><msub><mrow><mi>η</mi></mrow><mrow><mi>B</mi></mrow></msub><mo>(</mo><msub><mrow><mi>η</mi></mrow><mrow><mover><mrow><mi>B</mi></mrow><mrow><mo>¯</mo></mrow></mover></mrow></msub><mo>)</mo></math></span> is number of baryon (anti baryon). We take four different models from Einstein-Æther gravity to analyze the ratio <span><math><mfrac><mrow><msub><mrow><mi>η</mi></mrow><mrow><mi>B</mi></mrow></msub></mrow><mrow><mi>s</mi></mrow></mfrac></math></span> and compared our outcomes with the observational bounds. We found this ratio is consistent with the observational data. For a further verification, we examine the Hubble parameter (<em>H</em>) for each model and compared them with observational values, finding a high degree of agreement. Additionally, we perform Chi-square (<span><math><msup><mrow><mi>χ</mi></mrow><mrow><mn>2</mn></mrow></msup></math></span>) test on Hubble parameter for each model to assess their compatibility with recent observational data. Furthermore, we compared our findings with the ΛCDM model and the latest Pantheon+SH0ES observational data. This comparison unveiled a reasonable level of consistency among the considered models and the observational data.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"45 ","pages":"Pages 135-145"},"PeriodicalIF":10.2,"publicationDate":"2024-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143098608","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":"Superflare on a rapidly-rotating solar-type star captured in X-rays","authors":"Andrey Mukhin ,&nbsp;Roman Krivonos ,&nbsp;Ilfan Bikmaev ,&nbsp;Mark Gorbachev ,&nbsp;Irek Khamitov ,&nbsp;Sergey Sazonov ,&nbsp;Marat Gilfanov ,&nbsp;Rashid Sunyaev","doi":"10.1016/j.jheap.2024.11.016","DOIUrl":"10.1016/j.jheap.2024.11.016","url":null,"abstract":"<div><div>In this work, we studied X-ray source SRGe J021932.4−040154 (SRGe J021932), which we associated with a single X-ray active star of spectral class G2V-G4V and the rotational period <span><math><msub><mrow><mi>P</mi></mrow><mrow><mi>rot</mi></mrow></msub><mo>&lt;</mo><mn>9.3</mn></math></span> days. Additional analysis of TESS light-curves allowed for the rotational period estimation of <span><math><mn>3.2</mn><mo>±</mo><mn>0.5</mn></math></span> days. SRGe J021932 was observed with the <em>SRG</em>/eROSITA during eUDS survey in 2019 in a much dimmer state compared to the <em>XMM-Newton</em> catalogue 4XMM-DR12. Detailed analysis revealed that the archival <em>XMM-Newton</em> observations captured the source during a flaring event in 2017. The <em>XMM-Newton</em> light curve demonstrates a strong flare described with the Gaussian rise and exponential decay, typical for stellar flares, characterized by timescales of ∼400 s and ∼1300 s, respectively. The spectral analysis of the quiescent state reveals ∼10 MK plasma at luminosity of <span><math><mo>(</mo><mn>1.4</mn><mo>±</mo><mn>0.4</mn><mo>)</mo><mo>×</mo><msup><mrow><mn>10</mn></mrow><mrow><mn>29</mn></mrow></msup></math></span> <span><math><mi>erg</mi><mspace></mspace><msup><mrow><mi>s</mi></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup></math></span> (0.3−4.5 keV). The spectrum of the flare is characterized by temperature of ∼40 MK and luminosity <span><math><mo>(</mo><mn>5.5</mn><mo>±</mo><mn>0.6</mn><mo>)</mo><mo>×</mo><msup><mrow><mn>10</mn></mrow><mrow><mn>30</mn></mrow></msup></math></span> <span><math><mi>erg</mi><mspace></mspace><msup><mrow><mi>s</mi></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup></math></span>. The total energy emitted during the flare <span><math><mo>∼</mo><mn>1.7</mn><mo>×</mo><msup><mrow><mn>10</mn></mrow><mrow><mn>34</mn></mrow></msup></math></span> erg exceeds the canonical threshold of 10³³ erg, allowing us to classify the observed event as a superflare on a rapidly-rotating solar-type star. Additionally, we present the upper limit on the surface starspot area based on the brightness variations and consider the hypothesis of the object being a binary system with G-type and M-type stars, suggested by two independent estimations of radial velocity variations from APOGEE-2 and <em>Gaia</em>.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"45 ","pages":"Pages 105-115"},"PeriodicalIF":10.2,"publicationDate":"2024-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142720451","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 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}