Journal of High Energy Astrophysics最新文献

{"title":"Numerical studies of (in)stabilities of shocks in perturbed advective flows around black holes","authors":"Junxing Zhou ,&nbsp;Junxiang Huang ,&nbsp;Xin Chang ,&nbsp;Toru Okuda ,&nbsp;Chandra B. Singh","doi":"10.1016/j.jheap.2025.100395","DOIUrl":"10.1016/j.jheap.2025.100395","url":null,"abstract":"<div><div>Using two-dimensional hydrodynamic simulations, we investigate the stability of shocked accretion flows around black holes under non-axisymmetric perturbations. By systematically exploring the parameter space of specific energy and angular momentum that permits shock formation in advective accretion flows, we demonstrate that quasi-periodic oscillations (QPOs) naturally emerge in perturbed systems. Our spectral analysis reveals characteristic QPO frequencies spanning 0.44-146.57<em>Hz</em>, effectively bridging the observed low-frequency (LFQPOs) and high-frequency QPOs (HFQPOs) in black hole X-ray binaries. The quality factors (<span><math><mi>Q</mi><mo>=</mo><msub><mrow><mi>μ</mi></mrow><mrow><mn>0</mn></mrow></msub><mo>/</mo><mn>2</mn><mi>Δ</mi></math></span>) of these oscillations range from 1.66 to 203.58, with multiple Lorentzian components indicating distinct oscillation modes. Through wavelet analysis and cross-validation with recent observations (e.g., Swift J1727.8-1613 and GX 339-4), we establish that shock instabilities driven by acoustic wave interactions between the non-axisymmetric perturbation and the shock location can quantitatively explain the temporal features observed in accreting black hole systems. Furthermore, we characterize the <em>γ</em>-dependence of shock morphology, showing that increasing the adiabatic index from 4/3 to 1.4 changes shock positions outward while maintaining oscillation coherence.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"47 ","pages":"Article 100395"},"PeriodicalIF":10.2,"publicationDate":"2025-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143903721","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":"An explanation for the radio variation associated with the Vela pulsar glitch occurred on December 12 2016","authors":"Shuang Du","doi":"10.1016/j.jheap.2025.100393","DOIUrl":"10.1016/j.jheap.2025.100393","url":null,"abstract":"<div><div>The elaborate observation of the single radio pulses of Vela pulsar around the pulsar glitch that occurred on December 12, 2016 reveals that the physical mechanism associated with this glitch exerts a profound influence on the pulsar's magnetosphere. According to the evolution of these pulses, we propose a scenario regarding how the pulsar magnetic field might undergo alterations within the framework of the inner gap model. We deduce that the liberation of the free energy within Vela pulsar results in the emergence of new magnetic multipole components. The progressively developing multipole components cause the magnetic field lines in a section of the polar cap region to become increasingly curved, ultimately resulting in the observed pulse broadening and pulse missing. At last, we discuss the possible connection between magnetic variations and fast radio bursts according to the inspiration of the presented picture.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"47 ","pages":"Article 100393"},"PeriodicalIF":10.2,"publicationDate":"2025-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143882927","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":"Black holes immersed in polytropic scalar field gas","authors":"Y. Sekhmani ,&nbsp;S. Zare ,&nbsp;L.M. Nieto ,&nbsp;H. Hassanabadi ,&nbsp;K. Boshkayev","doi":"10.1016/j.jheap.2025.100389","DOIUrl":"10.1016/j.jheap.2025.100389","url":null,"abstract":"<div><div>By implementing the concept of polytropic structures as a scalar field gas with a dark energy-like behavior, we obtain a static spherically symmetric black hole solution in the framework of general relativity. In this paper, we study the quasinormal modes, the greybody bound process, the shadow behaviors, and the sparsity of black holes with a surrounding polytropic scalar field gas. Using the Wentzel-Kramers-Brillouin (WKB) approach, we evaluate the impact of a particular set of polytropic parameters <span><math><mo>(</mo><mi>ξ</mi><mo>,</mo><mi>A</mi><mo>)</mo></math></span> with a fixed setting of the polytropic index <em>n</em> on the oscillation frequency and damping rate of gravitational waves. The results show that the effect of the parameter <em>ξ</em> is much less significant than that of the parameter <em>A</em> on the gravitational waves oscillation frequency and damping rate. Furthermore, the analysis of the greybody factor bounds reveals special insight into the effect of certain parameters where the multipole moments <em>l</em> and the polytropic index <em>n</em> have similar effects, in contrast to the pair of polytropic parameters (<span><math><mi>ξ</mi><mo>,</mo><mi>A</mi></math></span>). In light of such a comparative study, we investigate, on the other hand, the third-order Padé WKB method, which results in a more accurate process for quasinormal mode frequencies compared to the third-order standard WKB method. In this way, exploring the sparsity of Hawking radiation is another task that provides a better understanding of the behavior of the black hole solution. In this respect, the results show that the black hole behaves like blackbody radiation for a sufficiently large entropy. And for <span><math><mi>ξ</mi><mo>=</mo><mi>A</mi><mo>=</mo><mn>0</mn></math></span>, the relevant sparsity acts exactly like the Schwarzschild sparsity. These results provide an insight into the dynamics of black holes with a surrounding polytropic scalar field gas from the analysis of their quasinormal modes, greybody factors, shadow behaviors, energy emission rate and sparsity process. Constraints on the associated BH parameters, derived from the Event Horizon Telescope observations of M87* and Sgr A*, indicate that this black hole model stands as a compelling candidate for representing astrophysical black holes.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"47 ","pages":"Article 100389"},"PeriodicalIF":10.2,"publicationDate":"2025-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143865168","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 thermonuclear bursts and X-ray reflection features in Aql X-1 during 2024 outburst","authors":"Manoj Mandal ,&nbsp;Sabyasachi Pal ,&nbsp;G.K. Jaisawal ,&nbsp;Anne Lohfink ,&nbsp;Sachindra Naik ,&nbsp;Jaiverdhan Chauhan","doi":"10.1016/j.jheap.2025.100387","DOIUrl":"10.1016/j.jheap.2025.100387","url":null,"abstract":"<div><div>We report the broadband timing and spectral properties of the neutron star low-mass X-ray binary Aql X-1 during the 2024 outburst with <em>NICER</em>, <em>NuSTAR</em>, and <em>Swift</em> observatories. We detected six thermonuclear X-ray bursts during the <em>NICER</em> and <em>NuSTAR</em> observations, with the observed X-ray burst profiles exhibiting a strong energy dependence. The time-resolved burst spectra indicate the presence of soft excess during the burst, which can be modeled by using a variable persistent emission method (<span><math><msub><mrow><mi>f</mi></mrow><mrow><mi>a</mi></mrow></msub></math></span> method) or the <span>relxillNS</span> reflection model. We found that the reflection model can contribute ∼20% of total emission as observed during the <em>NICER</em> burst. The reflection and blackbody component fluxes are strongly correlated, as observed during a burst. The excess emission is possible due to the enhanced mass accretion rate to the neutron star due to the Poynting-Rodertson drag, and a fraction of burst emission may be reflected from the disk. The bursts did not show photospheric radius expansion during the peak. Moreover, we examined the burst-free accretion emission in the broadband range with <em>NuSTAR</em>, <em>NICER</em>, and <em>Swift</em> at two epochs of the outburst. The persistent emission showed X-ray reflection features, which can be well modeled with the relativistic reflection model <span>relxillCp</span>. The inner disk radius (R<span><math><msub><mrow></mrow><mrow><mi>i</mi><mi>n</mi></mrow></msub></math></span>) is found to be nearly 22 and 10 times <span><math><msub><mrow><mi>R</mi></mrow><mrow><mi>g</mi></mrow></msub></math></span> for two observations, respectively. Assuming that the inner disk is truncated at the magnetospheric radius, the magnetic field strength at the poles of the neutron star is estimated to be <span><math><mo>(</mo><mn>0.6</mn><mo>−</mo><mn>1.9</mn><mo>)</mo><mo>×</mo><msup><mrow><mn>10</mn></mrow><mrow><mn>9</mn></mrow></msup></math></span> G.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"47 ","pages":"Article 100387"},"PeriodicalIF":10.2,"publicationDate":"2025-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143865166","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":"Phantom dark energy cosmological models in f(R,T,Lm) gravity","authors":"Dinesh Chandra Maurya ,&nbsp;Rashid Zia","doi":"10.1016/j.jheap.2025.100392","DOIUrl":"10.1016/j.jheap.2025.100392","url":null,"abstract":"<div><div>In the present paper, we have investigated <span><math><mi>f</mi><mo>(</mo><mi>R</mi><mo>,</mo><mi>T</mi><mo>,</mo><msub><mrow><mi>L</mi></mrow><mrow><mi>m</mi></mrow></msub><mo>)</mo></math></span> gravity cosmological models with a perfect fluid source in a flat Friedmann-Lemaître-Robertson-Walker (FLRW) spacetime. We analytically solved the field equations and obtained the energy density <em>ρ</em>, Hubble function <em>H</em>, scale factor <em>a</em>, deceleration parameter <em>q</em>, effective energy density <span><math><msub><mrow><mi>ρ</mi></mrow><mrow><mi>e</mi><mi>f</mi><mi>f</mi></mrow></msub></math></span>, effective pressure <span><math><msub><mrow><mi>p</mi></mrow><mrow><mi>e</mi><mi>f</mi><mi>f</mi></mrow></msub></math></span>, effective equation of state (EoS) parameter <span><math><msub><mrow><mi>ω</mi></mrow><mrow><mi>e</mi><mi>f</mi><mi>f</mi></mrow></msub></math></span> and dark energy EoS parameter <span><math><msub><mrow><mi>ω</mi></mrow><mrow><mi>d</mi><mi>e</mi></mrow></msub></math></span>. By performing Monte Carlo Markov Chain (MCMC) analysis of 31 cosmic chronometer (CC) Hubble data and 1048 apparent magnitude data of Pantheon sample of SNe Ia we get observational constraints on the model parameters <span><math><msub><mrow><mi>H</mi></mrow><mrow><mn>0</mn></mrow></msub></math></span>, <span><math><msub><mrow><mi>Ω</mi></mrow><mrow><mi>m</mi><mn>0</mn></mrow></msub></math></span>, <em>α</em>, <em>β</em> and <em>ω</em>. Using these, we investigate the behavior of the cosmological parameters, <span><math><msub><mrow><mi>ρ</mi></mrow><mrow><mi>d</mi><mi>e</mi></mrow></msub></math></span>, <span><math><msub><mrow><mi>p</mi></mrow><mrow><mi>d</mi><mi>e</mi></mrow></msub></math></span>, <span><math><msub><mrow><mi>ω</mi></mrow><mrow><mi>e</mi><mi>f</mi><mi>f</mi></mrow></msub></math></span>, <span><math><msub><mrow><mi>ω</mi></mrow><mrow><mi>d</mi><mi>e</mi></mrow></msub></math></span>, <span><math><msub><mrow><mi>Ω</mi></mrow><mrow><mi>m</mi></mrow></msub></math></span>, <span><math><msub><mrow><mi>Ω</mi></mrow><mrow><mi>d</mi><mi>e</mi></mrow></msub></math></span>, and <em>q</em>. For physical acceptability, validity and viability of the derived model, we tested the energy conditions, calculated causality <span><math><msubsup><mrow><mi>c</mi></mrow><mrow><mi>s</mi></mrow><mrow><mn>2</mn></mrow></msubsup></math></span>, performed om diagnostic <span><math><mi>O</mi><mi>m</mi><mo>(</mo><mi>z</mi><mo>)</mo></math></span> and also estimate the age of the Universe. We have found that our derived model shows consistency with most of the observed cosmological parameters and resembles Phantom dark energy cosmological models.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"47 ","pages":"Article 100392"},"PeriodicalIF":10.2,"publicationDate":"2025-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143882926","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":"Fermi-LAT and FAST observation of the gamma-ray binary HESS J0632+057","authors":"Yanlv Yang ,&nbsp;Dengke Zhou ,&nbsp;Zihao Zhao ,&nbsp;Jian Li ,&nbsp;Diego F. Torres ,&nbsp;Pei Wang","doi":"10.1016/j.jheap.2025.100388","DOIUrl":"10.1016/j.jheap.2025.100388","url":null,"abstract":"<div><div>Using 15 years of data from the <em>Fermi</em> Large Area Telescope (<em>Fermi</em>-LAT), we performed a comprehensive analysis on the gamma-ray binary HESS J0632+057. Its spectrum in 0.1–300 GeV band is well described by a power law model with an index of <span><math><mn>2.40</mn><mo>±</mo><mn>0.16</mn></math></span>, leading to an energy flux of (5.5±1.6)× 10⁻¹² erg cm⁻² s⁻¹. The GeV Spectral Energy Distribution (SED) of HESS J0632+057 hints for a spectral turn-over between ∼10-100 GeV. Orbital analysis reveals a flux enhancement during the phase range of 0.2-0.4, consistent with the X-ray and TeV light curves, indicating an origin of a common particle population. We carried out six deep radio observations on HESS J0632+057 with the Five-hundred-meter Aperture Spherical Telescope (FAST), evenly distributed across its orbit, reaching a detection sensitivity of 2<em>μ</em>Jy. However, no radio pulsation was detected within these observations. The absence of radio pulsation may be attributed to the dense stellar wind environment of HESS J0632+057.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"47 ","pages":"Article 100388"},"PeriodicalIF":10.2,"publicationDate":"2025-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143882925","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":"Implication of f(Q,T) gravity on the formation of the charge compact stars and constraining their mass-radius relations in lower mass gap region","authors":"S.K. Maurya ,&nbsp;A. Errehymy ,&nbsp;Z. Umbetova ,&nbsp;K. Myrzakulov ,&nbsp;I. Ibragimov ,&nbsp;A. Dauletov ,&nbsp;J. Rayimbaev","doi":"10.1016/j.jheap.2025.100391","DOIUrl":"10.1016/j.jheap.2025.100391","url":null,"abstract":"<div><div>In this paper, we explore a charged isotropic stellar model within the framework of <span><math><mi>f</mi><mo>(</mo><mi>Q</mi><mo>,</mo><mi>T</mi><mo>)</mo></math></span> gravity. By deriving solutions to the modified field equations, we systematically analyze the physical characteristics of the stellar configuration to assess its relevance and stability. Our results show that the electric charge distribution adheres to key criteria of regularity and finiteness. Notably, the charge behavior is significantly affected by the charge parameter <em>σ</em> and the coupling parameter <em>m</em>, while demonstrating stability in response to variations in <em>n</em>. We find that the surface charge ranges from <span><math><mn>1.85</mn><mo>×</mo><msup><mrow><mn>10</mn></mrow><mrow><mn>20</mn></mrow></msup></math></span> C to <span><math><mn>3.31</mn><mo>×</mo><msup><mrow><mn>10</mn></mrow><mrow><mn>20</mn></mrow></msup></math></span> C, which is consistent with prior research, highlighting the crucial role of electric charge in maintaining stellar stability against gravitational collapse. Additionally, our analysis of density and isotropic pressure reveals both quantities to be finite and regular at the core, effectively eliminating the presence of singularities. The central density aligns well with typical neutron star configurations, while the isotropic pressure approaches zero at the boundary. Investigating the causality conditions, we confirm that the sound speed remains subluminal, and the adiabatic index <span><math><mi>Γ</mi><mo>(</mo><mi>r</mi><mo>)</mo></math></span> exceeds the critical threshold of <span><math><mfrac><mrow><mn>4</mn></mrow><mrow><mn>3</mn></mrow></mfrac></math></span>, indicating stability throughout the stellar configuration. The equilibrium of forces, evaluated through modified TOV equations, illustrates a harmonious balance among gravitational, electrostatic, and hydrostatic forces. The relationship between mass and radius indicates a maximum mass ranging from <span><math><mn>1.83</mn><msub><mrow><mi>M</mi></mrow><mrow><mo>⊙</mo></mrow></msub></math></span> to <span><math><mn>2.99</mn><msub><mrow><mi>M</mi></mrow><mrow><mo>⊙</mo></mrow></msub></math></span>, with radii that are consistent with observational data. In conclusion, our findings underscore the substantial impact of the charge parameter <em>σ</em> in enhancing the compactness and stability of higher-mass compact stars, providing support for the existence of stars within the mass gap region.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"47 ","pages":"Article 100391"},"PeriodicalIF":10.2,"publicationDate":"2025-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143886681","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 the initial Lorentz factor of gamma-ray bursts under different circumburst mediums","authors":"Sheng-Jin Sun ,&nbsp;Shuang-Xi Yi ,&nbsp;Yuan-Chuan Zou ,&nbsp;Yu-Peng Yang ,&nbsp;Ying Qin ,&nbsp;Qing-Wen Tang ,&nbsp;Fa-Yin Wang","doi":"10.1016/j.jheap.2025.100390","DOIUrl":"10.1016/j.jheap.2025.100390","url":null,"abstract":"&lt;div&gt;&lt;div&gt;The initial Lorentz factor (&lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;Γ&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mtext&gt;0&lt;/mtext&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt;) plays a crucial role in uncovering the physical characteristics of gamma-ray bursts (GRBs). Previous studies have indicated that the ambient medium density index &lt;em&gt;k&lt;/em&gt; for GRBs falls in the range of 0 - 2, rather than exactly equal to 0 (homogeneous interstellar ambient) or 2 (typical stellar wind). In this work, we aim to constrain the &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;Γ&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt; of GRBs considering their distinct circumburst medium. We select a total of 33 GRBs for our analysis, comprising 7 X-ray GRBs and 26 optical GRBs. Subsequently, by utilizing the deceleration time of fireball &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;t&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;p&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt;, we derive the &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;Γ&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt; for the 33 GRBs assuming the radiation efficiency of &lt;em&gt;η&lt;/em&gt;= 0.2. The inferred initial Lorentz factor was found to be from 50 to 500, consistent with previous studies. We then investigate the correlation between the &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;Γ&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt; and the isotropic energy &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;E&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;γ&lt;/mi&gt;&lt;mo&gt;,&lt;/mo&gt;&lt;mrow&gt;&lt;mi&gt;iso&lt;/mi&gt;&lt;/mrow&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt; (as well as the mean isotropic luminosity &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;L&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;γ&lt;/mi&gt;&lt;mo&gt;,&lt;/mo&gt;&lt;mrow&gt;&lt;mi&gt;iso&lt;/mi&gt;&lt;/mrow&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt;), finding very tight correlations between them, i.e., &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;Γ&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt; ∝ &lt;span&gt;&lt;math&gt;&lt;msubsup&gt;&lt;mrow&gt;&lt;mi&gt;E&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;γ&lt;/mi&gt;&lt;mo&gt;,&lt;/mo&gt;&lt;mrow&gt;&lt;mi&gt;iso&lt;/mi&gt;&lt;/mrow&gt;&lt;mo&gt;,&lt;/mo&gt;&lt;mn&gt;52&lt;/mn&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;0.24&lt;/mn&gt;&lt;/mrow&gt;&lt;/msubsup&gt;&lt;/math&gt;&lt;/span&gt; (&lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;Γ&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt; ∝ &lt;span&gt;&lt;math&gt;&lt;msubsup&gt;&lt;mrow&gt;&lt;mi&gt;L&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;γ&lt;/mi&gt;&lt;mo&gt;,&lt;/mo&gt;&lt;mrow&gt;&lt;mi&gt;iso&lt;/mi&gt;&lt;mo&gt;.&lt;/mo&gt;&lt;mn&gt;49&lt;/mn&gt;&lt;/mrow&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;0.20&lt;/mn&gt;&lt;/mrow&gt;&lt;/msubsup&gt;&lt;/math&gt;&lt;/span&gt;) with &lt;em&gt;η&lt;/em&gt;=0.2. Additionally, we verify the correlation among &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;Γ&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt;, the isotropic energy &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;E&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;γ&lt;/mi&gt;&lt;mo&gt;,&lt;/mo&gt;&lt;mrow&gt;&lt;mi&gt;iso&lt;/mi&gt;&lt;/mrow&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt; (or &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;L&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;γ&lt;/mi&gt;&lt;mo&gt;,&lt;/mo&gt;&lt;mrow&gt;&lt;mi&gt;iso&lt;/mi&gt;&lt;/mrow&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt;) and the peak energy &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;E&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;p&lt;/mi&gt;&lt;mo&gt;,&lt;/mo&gt;&lt;mi&gt;z&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt;, i.e., &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;E&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;γ&lt;/mi&gt;&lt;mo&gt;,&lt;/mo&gt;&lt;mrow&gt;&lt;mi&gt;iso&lt;/mi&gt;&lt;/mrow&gt;&lt;mo&gt;,&lt;/mo&gt;&lt;mn&gt;52&lt;/mn&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt; ∝ &lt;span&gt;&lt;math&gt;&lt;msubsup&gt;&lt;mrow&gt;&lt;mi&gt;Γ&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;1.36&lt;/mn&gt;&lt;/mrow&gt;&lt;/msubsup&gt;&lt;/math&gt;&lt;/span&gt;&lt;span&gt;&lt;math&gt;&lt;msubsup&gt;&lt;mrow&gt;&lt;mi&gt;E&lt;","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"47 ","pages":"Article 100390"},"PeriodicalIF":10.2,"publicationDate":"2025-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143865167","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":"Diagnostics of dark energy evolution using logarithmic Om(z) parameterization","authors":"Y. Myrzakulov ,&nbsp;Alnadhief H.A. Alfedeel ,&nbsp;M. Koussour ,&nbsp;E.I. Hassan ,&nbsp;S. Muminov","doi":"10.1016/j.jheap.2025.100386","DOIUrl":"10.1016/j.jheap.2025.100386","url":null,"abstract":"<div><div>In this study, we explore the logarithmic <span><math><mi>O</mi><mi>m</mi><mo>(</mo><mi>z</mi><mo>)</mo></math></span> parameterization as a tool for diagnosing the nature and evolution of dark energy. We propose the form <span><math><mi>O</mi><mi>m</mi><mo>(</mo><mi>z</mi><mo>)</mo><mo>=</mo><mi>α</mi><mi>ln</mi><mo>⁡</mo><mo>(</mo><mn>1</mn><mo>+</mo><mi>z</mi><mo>)</mo><mo>+</mo><mi>β</mi></math></span>, where <em>α</em> and <em>β</em> are free parameters, and analyze its behavior for different values of <em>α</em>. When <span><math><mi>α</mi><mo>=</mo><mn>0</mn></math></span>, the model reduces to a constant, consistent with the cosmological constant, while <span><math><mi>α</mi><mo>≠</mo><mn>0</mn></math></span> indicates dynamical dark energy, with <span><math><mi>α</mi><mo>&gt;</mo><mn>0</mn></math></span> suggesting phantom-like behavior and <span><math><mi>α</mi><mo>&lt;</mo><mn>0</mn></math></span> indicating quintessence-like dynamics. By constraining the model parameters using observational datasets such as OHD, the Pantheon+ sample, and the combined dataset (OHD+SNe+BAO), we obtain tight constraints on the cosmic evolution. Our results suggest a mild deviation from the standard ΛCDM model, with a slight preference for phantom-like behavior at low redshifts. The deceleration parameter and equation of state parameter were analyzed to understand the cosmic transition from deceleration to acceleration, with a transition redshift around <span><math><msub><mrow><mi>z</mi></mrow><mrow><mi>t</mi><mi>r</mi></mrow></msub><mo>≈</mo><mn>0.6</mn><mo>−</mo><mn>0.8</mn></math></span>. The present-day deceleration parameter was found to range from <span><math><msub><mrow><mi>q</mi></mrow><mrow><mn>0</mn></mrow></msub><mo>=</mo><mo>−</mo><mn>0.55</mn></math></span> to <span><math><msub><mrow><mi>q</mi></mrow><mrow><mn>0</mn></mrow></msub><mo>=</mo><mo>−</mo><mn>0.60</mn></math></span>, and the EoS parameter values varied between <span><math><msub><mrow><mi>ω</mi></mrow><mrow><mn>0</mn></mrow></msub><mo>=</mo><mo>−</mo><mn>0.70</mn></math></span> and <span><math><msub><mrow><mi>ω</mi></mrow><mrow><mn>0</mn></mrow></msub><mo>=</mo><mo>−</mo><mn>0.73</mn></math></span>. The inferred Hubble constant values exhibit dataset-dependent variations, highlighting the persistent Hubble tension. Our analysis suggests that the logarithmic <span><math><mi>O</mi><mi>m</mi><mo>(</mo><mi>z</mi><mo>)</mo></math></span> parameterization offers a flexible framework for studying cosmic acceleration.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"47 ","pages":"Article 100386"},"PeriodicalIF":10.2,"publicationDate":"2025-04-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143859606","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 strong gravitational lensing around black hole-like compact object in quadratic gravity","authors":"Somi Aktar ,&nbsp;Niyaz Uddin Molla ,&nbsp;Farook Rahaman ,&nbsp;G. Mustafa","doi":"10.1016/j.jheap.2025.100385","DOIUrl":"10.1016/j.jheap.2025.100385","url":null,"abstract":"<div><div>We investigate the astrophysical consequences of black holes in quadratic gravity, characterized by the parameters <span><math><msub><mrow><mi>S</mi></mrow><mrow><mn>0</mn></mrow></msub></math></span>, <span><math><msub><mrow><mi>S</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span>, <span><math><msub><mrow><mi>m</mi></mrow><mrow><mn>0</mn></mrow></msub></math></span> and <span><math><msub><mrow><mi>m</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span>, in addition to the black hole mass <em>M</em>. To evaluate the physical validity of the fundamental quadratic gravity black hole solutions, we analyze their gravitational lensing properties in the strong deflection limit. Specifically, we examine the shadow cast by the quadratic gravity black hole and constrain its parameters using observational data from the <span><math><mi>M</mi><msup><mrow><mn>87</mn></mrow><mrow><mo>⁎</mo></mrow></msup></math></span> and <span><math><mi>S</mi><mi>g</mi><mi>r</mi><msup><mrow><mi>A</mi></mrow><mrow><mo>⁎</mo></mrow></msup></math></span> supermassive black holes. Our analysis reveals that, within the 1<em>σ</em> confidence level, a significant portion of the parameter space for quadratic gravity black holes is consistent with the Event Horizon Telescope (EHT) observations of <span><math><mi>M</mi><msup><mrow><mn>87</mn></mrow><mrow><mo>⁎</mo></mrow></msup></math></span> and <span><math><mi>S</mi><mi>g</mi><mi>r</mi><msup><mrow><mi>A</mi></mrow><mrow><mo>⁎</mo></mrow></msup></math></span>. This suggests that these black holes are plausible candidates for describing astrophysical black holes. As an additional observational test, we perform a detailed investigation of the strong deflection limit properties of these black holes. We explore the fundamental lensing observables in detail, including the angular positions and separations of the lensed images, the relative magnifications, the radius of the outermost Einstein ring, and the relativistic time delay between images. We compare the predictions of the quadratic gravity black hole for each observable with those of the classical Schwarzschild solution using realistic astrophysical data. Our findings provide a pathway for testing quadratic gravity at the galactic and extragalactic scales, offering new insights into the observational properties of black hole solutions within this framework.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"47 ","pages":"Article 100385"},"PeriodicalIF":10.2,"publicationDate":"2025-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143843745","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}