Journal of High Energy Astrophysics最新文献

{"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}

{"title":"Constraining anisotropic universe under f(R,T) theory of gravity","authors":"Lokesh Kumar Sharma ,&nbsp;Suresh Parekh ,&nbsp;Saibal Ray ,&nbsp;Anil Kumar Yadav","doi":"10.1016/j.jheap.2024.11.001","DOIUrl":"10.1016/j.jheap.2024.11.001","url":null,"abstract":"<div><div>We investigate the possibility of a Bianchi V universe in the modified gravitational field theory of <span><math><mi>f</mi><mo>(</mo><mi>R</mi><mo>,</mo><mi>T</mi><mo>)</mo></math></span>. We have considered a Lagrangian model in connection between the trace of the energy-momentum tensor <em>T</em> and the Ricci scalar <em>R</em>. In order to solve the field equations a power law for the scaling factor was also considered. To make a comparison of the model parameters with the observational data we put constraint on the model under the datasets of the Hubble parameter, Baryon Acoustic Oscillations, Pantheon, joint datasets of Hubble parameter + Pantheon and collective datasets of the Hubble parameter + Baryon Acoustic Oscillations + Pantheon. The outcomes for the Hubble parameter in the present epoch are reasonably acceptable, especially our estimation of this <span><math><msub><mrow><mi>H</mi></mrow><mrow><mn>0</mn></mrow></msub></math></span> is remarkably consistent with various recent Planck Collaboration studies that utilize the Λ-CDM model.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"44 ","pages":"Pages 457-467"},"PeriodicalIF":10.2,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142656021","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":"Study of anisotropic quark stars with interacting quark matter in f(R,T) gravity","authors":"Abdelghani Errehymy ,&nbsp;Indrani Karar ,&nbsp;Kairat Myrzakulov ,&nbsp;Ayan Banerjee ,&nbsp;Abdel-Haleem Abdel-Aty ,&nbsp;Kottakkaran Sooppy Nisar","doi":"10.1016/j.jheap.2024.10.016","DOIUrl":"10.1016/j.jheap.2024.10.016","url":null,"abstract":"&lt;div&gt;&lt;div&gt;We explore the structural properties of quark stars (QSs) in a modified gravity theory known as &lt;span&gt;&lt;math&gt;&lt;mi&gt;f&lt;/mi&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mi&gt;R&lt;/mi&gt;&lt;mo&gt;,&lt;/mo&gt;&lt;mi&gt;T&lt;/mi&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/math&gt;&lt;/span&gt; gravity, which introduces a coupling between matter and spacetime geometry, through a basic linear functional form &lt;span&gt;&lt;math&gt;&lt;mi&gt;f&lt;/mi&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mi&gt;R&lt;/mi&gt;&lt;mo&gt;,&lt;/mo&gt;&lt;mi&gt;T&lt;/mi&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mi&gt;R&lt;/mi&gt;&lt;mo&gt;+&lt;/mo&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;mi&gt;β&lt;/mi&gt;&lt;mi&gt;T&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt;. Our study focuses on QSs made of interacting quark matter (IQM) as an equation of state. We first derive the modified Tolman-Oppenheimer-Volkoff (TOV) equations for anisotropic matter in a spherically symmetric context and solve them numerically to obtain the structural properties of QSs. Stability is analyzed through static stability analysis, critical adiabatic indices, and sound speed profiles. Using astrophysical constraints from the “black widow” pulsar PSR J0952-0607 and the GW190814 event, we calibrate our model parameters. Our results indicate that with higher &lt;span&gt;&lt;math&gt;&lt;mover&gt;&lt;mrow&gt;&lt;mi&gt;λ&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mo&gt;¯&lt;/mo&gt;&lt;/mrow&gt;&lt;/mover&gt;&lt;/math&gt;&lt;/span&gt;, both the maximum mass and radius of QSs increase, achieving a maximum mass of over &lt;span&gt;&lt;math&gt;&lt;mn&gt;2&lt;/mn&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;, peaking at &lt;span&gt;&lt;math&gt;&lt;mn&gt;3.15&lt;/mn&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; for a radius of &lt;span&gt;&lt;math&gt;&lt;mn&gt;14.90&lt;/mn&gt;&lt;mspace&gt;&lt;/mspace&gt;&lt;mtext&gt;km&lt;/mtext&gt;&lt;/math&gt;&lt;/span&gt; at &lt;span&gt;&lt;math&gt;&lt;mover&gt;&lt;mrow&gt;&lt;mi&gt;λ&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mo&gt;¯&lt;/mo&gt;&lt;/mrow&gt;&lt;/mover&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;0.9&lt;/mn&gt;&lt;/math&gt;&lt;/span&gt;. The maximum compactness also rises to &lt;span&gt;&lt;math&gt;&lt;mi&gt;M&lt;/mi&gt;&lt;mo&gt;/&lt;/mo&gt;&lt;mi&gt;R&lt;/mi&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;0.313&lt;/mn&gt;&lt;/math&gt;&lt;/span&gt; while adhering to the Buchdahl limit. Additionally, varying &lt;em&gt;β&lt;/em&gt; in the range &lt;span&gt;&lt;math&gt;&lt;mo&gt;[&lt;/mo&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mn&gt;0.2&lt;/mn&gt;&lt;mo&gt;,&lt;/mo&gt;&lt;mn&gt;0.2&lt;/mn&gt;&lt;mo&gt;]&lt;/mo&gt;&lt;/math&gt;&lt;/span&gt; with fixed parameters shows that lower &lt;em&gt;β&lt;/em&gt; values enhance the maximum mass of QSs, reaching &lt;span&gt;&lt;math&gt;&lt;mn&gt;2.65&lt;/mn&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; at &lt;span&gt;&lt;math&gt;&lt;mi&gt;β&lt;/mi&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mn&gt;0.2&lt;/mn&gt;&lt;/math&gt;&lt;/span&gt;, with the compactness remaining around &lt;span&gt;&lt;math&gt;&lt;mi&gt;M&lt;/mi&gt;&lt;mo&gt;/&lt;/mo&gt;&lt;mi&gt;R&lt;/mi&gt;&lt;mo&gt;≈&lt;/mo&gt;&lt;mn&gt;0.3&lt;/mn&gt;&lt;/math&gt;&lt;/span&gt;. Furthermore, changes in &lt;em&gt;μ&lt;/em&gt; from &lt;span&gt;&lt;math&gt;&lt;mo&gt;[&lt;/mo&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mn&gt;1.0&lt;/mn&gt;&lt;mo&gt;,&lt;/mo&gt;&lt;mn&gt;1.0&lt;/mn&gt;&lt;mo&gt;]&lt;/mo&gt;&lt;/math&gt;&lt;/span&gt; significantly affect maximum mass; at &lt;span&gt;&lt;math&gt;&lt;mi&gt;μ&lt;/mi&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;1.0&lt;/mn&gt;&lt;/math&gt;&lt;/span&gt;, the mass peaks at &lt;span&gt;&lt;math&gt;&lt;mn&gt;3.15&lt;/mn&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; and decrease to &lt;span&gt;&lt;math&gt;&lt;mn&gt;2.68&lt;/mn&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; at &lt;span&gt;&lt;math&gt;&lt;mi&gt;μ&lt;/mi&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;/math&gt;&lt;/span&gt;. The compactness increases with &lt;em&gt;μ&lt;/em&gt;, indicating that anisotropic pressure influences the &lt;span&gt;&lt;math&gt;&lt;mi&gt;M&lt;/mi&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mi&gt;R&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt; relations. In summary, our f","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"44 ","pages":"Pages 410-418"},"PeriodicalIF":10.2,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142578483","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":"Weak cosmic censorship and weak gravity conjectures in CFT thermodynamics","authors":"Jafar Sadeghi ,&nbsp;Saeed Noori Gashti ,&nbsp;Mohammad Reza Alipour ,&nbsp;Mohammad Ali S. Afshar","doi":"10.1016/j.jheap.2024.11.004","DOIUrl":"10.1016/j.jheap.2024.11.004","url":null,"abstract":"<div><div>In this paper, we explore the intriguing interplay between fundamental theoretical physics concepts within the context of charged black holes. Specifically, we focus on the consistency of the weak gravity conjecture (WGC) and weak cosmic censorship conjecture (WCCC) in the thermodynamics of conformal field theory (CFT), and restricted phase space thermodynamics (RPST) for AdS Reissner-Nordström black holes with a perfect fluid dark matter (RN-PFDM). The WGC ensures that gravity remains the weakest force in the system. Meanwhile, the WCCC addresses the cosmic censorship problem by preventing the violation of fundamental physical laws near the black hole singularity. First, we analyze the RN black hole's free energy in both spaces, revealing a distinctive swallowtail pattern indicative of a first-order phase transition when certain free parameter conditions are met. We explore the WGC across different phase spaces, emphasizing the need for certain conditions in extended phase space thermodynamics (EPST), RPST, and CFT. We demonstrate that PFDM parameter <em>γ</em> and the radius of AdS <em>l</em> have a vital role in proving the satisfaction of the WGC. Also, these values have a linear relation with the range compatibility of WGC. The range of compatibility for WGC in RPST and EPST is the same while for CFT, this range is larger than EPST, and RPST. It means somehow the WGC and CFT are more consistent. The WCCC was examined at the critical juncture, confirming its validity in critical points. We conclude that the WGC is supported at the critical point of black holes, and the WCCC is also maintained, demonstrating the robustness of these conjectures within the critical ranges of black hole parameters.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"44 ","pages":"Pages 482-493"},"PeriodicalIF":10.2,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142656501","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":"Exact solution to the Wheeler-DeWitt equation: Early and current Universe","authors":"David Senjaya","doi":"10.1016/j.jheap.2024.11.007","DOIUrl":"10.1016/j.jheap.2024.11.007","url":null,"abstract":"<div><div>In this paper, we present exact solutions to the Wheeler-DeWitt equation in two different scenarios: the early Universe, where the ordering parameter of kinetic energy is important, and the current Universe, where the ordering parameter effect is negligible. To make the exact solutions as general as possible, we incorporate as many different types of energy density as possible into the Hamiltonian, including baryonic and non-baryonic matter (dark matter), radiation, vacuum, and quintessence (dark energy). In the early Universe scenario, we obtain exact solutions in terms of the Biconfluent Heun functions, whereas in the current Universe, the exact solutions are given in terms of the Triconfluent Heun functions. Furthermore, by applying the polynomial conditions to each case, we obtain a constraint equation that supports the notion that the Wheeler-DeWitt equation can be viewed as an eigenvalue problem for the cosmological constant.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"44 ","pages":"Pages 494-499"},"PeriodicalIF":10.2,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142656507","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":"General relativistic viscous accretion flow around Konoplya-Zhidenko black hole","authors":"Subhankar Patra,&nbsp;Bibhas Ranjan Majhi,&nbsp;Santabrata Das","doi":"10.1016/j.jheap.2024.10.012","DOIUrl":"10.1016/j.jheap.2024.10.012","url":null,"abstract":"<div><div>We investigate the properties of accretion flows around the Konoplya-Zhidenko (KZ) black hole, which is proposed by deforming the Kerr metric with a single deformation parameter to test the no-hair theorem using gravitational wave observations. The dynamical equations describing the general relativistic viscous accreting flow are solved self-consistently to find the transonic accretion solutions in terms of global constants, such as energy (<em>E</em>), angular momentum (<span><math><mi>L</mi></math></span>), viscosity parameter (<em>α</em>), spin (<span><math><msub><mrow><mi>a</mi></mrow><mrow><mi>k</mi></mrow></msub></math></span>), and deformation parameter (<span><math><msub><mrow><mi>η</mi></mrow><mrow><mn>0</mn></mrow></msub></math></span>). We obtain five distinct types of accretion solutions (O, A, <span><math><msup><mrow><mtext>A</mtext></mrow><mrow><mo>′</mo></mrow></msup></math></span>, W, and I-types), and observe that those solutions are not unique but rather continue to exist for wide range of parameter spaces in the <span><math><mi>L</mi><mo>−</mo><mi>E</mi></math></span> plane. Furthermore, we find that the viscous accretion flows can harbor shock waves when the relativistic shock conditions are satisfied. Consequently, the shock-induced global accretion solutions are obtained, and the effect of <span><math><msub><mrow><mi>η</mi></mrow><mrow><mn>0</mn></mrow></msub></math></span> on shock properties, such as shock radius (<span><math><msub><mrow><mi>r</mi></mrow><mrow><mi>sh</mi></mrow></msub></math></span>) and change in electron temperature (<span><math><msub><mrow><mi>T</mi></mrow><mrow><mi>e</mi></mrow></msub></math></span>) across the shock front are investigated. Moreover, we calculate the spectral energy distributions (SEDs) of accretion flow using the relativistic thermal bremsstrahlung emission coefficient and study the modification of SEDs due to the increase of <span><math><msub><mrow><mi>η</mi></mrow><mrow><mn>0</mn></mrow></msub></math></span> for both shock-induced and shock-free solutions. In addition, it has been noticed that the observable quantities, like quasi-periodic oscillation frequency (<span><math><msub><mrow><mi>ν</mi></mrow><mrow><mi>QPO</mi></mrow></msub></math></span>) and bolometric disc luminosity (<em>L</em>), are strongly dependent on <span><math><msub><mrow><mi>η</mi></mrow><mrow><mn>0</mn></mrow></msub></math></span>. Finally, we phenomenologically show that the KZ black hole is consistent with the high-frequency QPOs, commonly observed in black hole binaries and black hole candidates.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"44 ","pages":"Pages 371-380"},"PeriodicalIF":10.2,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142554146","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":"Quantum-gravitational effects on Joule-Thomson expansion and black hole shadows in F(R) gravity with barrow entropy corrections","authors":"Muhammad Yasir ,&nbsp;Xia Tiecheng ,&nbsp;Shahid Chaudhary ,&nbsp;Abdulrahman Bin Jumah","doi":"10.1016/j.jheap.2024.10.006","DOIUrl":"10.1016/j.jheap.2024.10.006","url":null,"abstract":"<div><div>We present a novel investigation into the thermodynamic properties and shadow images of a topological phantom AdS black hole within the framework of <span><math><mi>F</mi><mo>(</mo><mi>R</mi><mo>)</mo></math></span> gravity, utilizing the Barrow entropy formulation. We introduce a detailed study of the Joule-Thomson expansion, calculating the Joule-Thomson coefficient and mapping isenthalpic and inversion curves to characterize heating/cooling phases. Our findings reveal that the Barrow parameter plays a crucial role in altering the shape and position of these thermodynamic curves, thereby significantly impacting the black hole's thermal behavior. Moreover, we demonstrate that variations in <span><math><mi>F</mi><mo>(</mo><mi>R</mi><mo>)</mo></math></span> gravity parameters such as the scalar curvature <span><math><msub><mrow><mi>R</mi></mrow><mrow><mn>0</mn></mrow></msub></math></span>, the type of field interaction <em>η</em>, and <span><math><msub><mrow><mi>f</mi></mrow><mrow><msub><mrow><mi>R</mi></mrow><mrow><mn>0</mn></mrow></msub></mrow></msub></math></span>—lead to substantial modifications in the shadow of the black hole. These changes in shadow size and shape underscore the direct influence of the underlying gravitational theory on the interaction between black holes and light, offering new perspectives on how black holes are perceived by distant observers. Additionally, we calculate the total observed intensities from the emission function of the accretion disk, with graphical analysis showing that the <span><math><mi>F</mi><mo>(</mo><mi>R</mi><mo>)</mo></math></span> gravity parameters markedly affect the intensity distribution around the black hole. This has significant implications for the accretion disk's emission properties and the resulting shadow image, highlighting the critical impact of modified gravity theories on observable black hole phenomena. This work offers fresh insights and underscores the importance of considering modified gravity frameworks when studying black hole thermodynamics and optical properties.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"44 ","pages":"Pages 356-370"},"PeriodicalIF":10.2,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142554145","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}