Physics of the Dark Universe最新文献_第5页

Reconstructing cosmic expansion in f(R,G) gravity using a log-periodic deceleration model 利用对数周期减速模型重建f（R，G）重力下的宇宙膨胀

IF 6.4 2区物理与天体物理

Physics of the Dark Universe Pub Date : 2025-09-12 DOI: 10.1016/j.dark.2025.102081

Amit Samaddar, S. Surendra Singh

引用次数: 0

Reheating constraints for an induced gravity model with a holographic description 带全息描述的诱导重力模型的再加热约束

IF 6.4 2区物理与天体物理

Physics of the Dark Universe Pub Date : 2025-09-12 DOI: 10.1016/j.dark.2025.102080

Farida Bargach , Aatifa Bargach , Brahim Asfour , Abdelkarim Oukouiss , Taoufik Ouali

{"title":"Reheating constraints for an induced gravity model with a holographic description","authors":"Farida Bargach , Aatifa Bargach , Brahim Asfour , Abdelkarim Oukouiss , Taoufik Ouali","doi":"10.1016/j.dark.2025.102080","DOIUrl":"10.1016/j.dark.2025.102080","url":null,"abstract":"<div><div>In this paper, we investigate an induced gravity model embedded in a holographic framework with a focus on a quadratic potential during the reheating phase. Although the reheating phase cannot be directly probed through cosmological observations, it can be indirectly constrained by studying the evolution of CMB modes from their horizon exit during inflation to the present time. In this setting, the reheating epoch is characterized by three essential parameters: the reheating temperature <span><math><msub><mrow><mi>T</mi></mrow><mrow><mtext>re</mtext></mrow></msub></math></span>, the number of e-folds during reheating, <span><math><msub><mrow><mi>N</mi></mrow><mrow><mtext>re</mtext></mrow></msub></math></span>, and the effective equation of state parameter, <span><math><msub><mrow><mi>ω</mi></mrow><mrow><mtext>re</mtext></mrow></msub></math></span>. These parameters provide a crucial link between the inflationary dynamics and the onset of the standard hot big bang phase. We derive meaningful constraints on the braneworld inflationary model by comparing how well our results align with the recent cosmological constraints from the combined dataset, incorporating Atacama Cosmology Telescope (ACT) DR6, Planck 2018, BICEP/Keck 2018 and DESI data (P-ACT-LB-BK18). To further examine the role of holographic cosmology in the reheating era, particularly after including induced gravity corrections on the brane, we analyze the reheating constraints for selected values of the holographic and induced gravity parameters, assuming fixed values of <span><math><msub><mrow><mi>ω</mi></mrow><mrow><mi>r</mi><mi>e</mi></mrow></msub></math></span> within the range <span><math><mrow><mo>−</mo><mn>1</mn><mo>/</mo><mn>3</mn><mo>≤</mo><msub><mrow><mi>ω</mi></mrow><mrow><mi>r</mi><mi>e</mi></mrow></msub><mo><</mo><mn>1</mn><mo>/</mo><mn>3</mn></mrow></math></span>. Under these conditions, and for the specific parameter choices <span><math><mrow><mi>c</mi><mo>≤</mo><mn>4</mn><mo>×</mo><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mn>7</mn></mrow></msup></mrow></math></span> and <span><math><mrow><mn>0</mn><mo>.</mo><mn>2</mn><mo><</mo><mi>γ</mi><mo>≤</mo><mn>0</mn><mo>.</mo><mn>6</mn></mrow></math></span>, our model produces results consistent with the latest observations. The reheating duration corresponds to the central value of the spectral index and satisfies the lower bound on the reheating temperature, thereby ensuring a consistent and physically viable cosmological scenario.</div></div>","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"50 ","pages":"Article 102080"},"PeriodicalIF":6.4,"publicationDate":"2025-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145049317","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}

引用次数: 0

Machine learning-based analytical expressions for Gray-Body Factors and application to Primordial Black Holes 基于机器学习的灰体因子解析表达式及其在原始黑洞中的应用

IF 6.4 2区物理与天体物理

Physics of the Dark Universe Pub Date : 2025-09-10 DOI: 10.1016/j.dark.2025.102078

Guan-Wen Yuan , Marco Calzà , Davide Pedrotti

{"title":"Machine learning-based analytical expressions for Gray-Body Factors and application to Primordial Black Holes","authors":"Guan-Wen Yuan , Marco Calzà , Davide Pedrotti","doi":"10.1016/j.dark.2025.102078","DOIUrl":"10.1016/j.dark.2025.102078","url":null,"abstract":"<div><div>Symbolic Regression (SR) is a machine learning approach that explores the space of mathematical expressions to identify those that best fit a given dataset, balancing both accuracy and simplicity. We apply SR to the study of Gray-Body Factors (GBFs), which play a crucial role in the derivation of Hawking radiation and are recognized for their computational complexity. We explore simple analytical forms for the GBFs of the Schwarzschild Black Hole (BH). We compare the results obtained with different approaches and quantify their consistency with those obtained by solving the Teukolsky equation. As a case study, we apply our pipeline, which we call <span>ReGrayssion</span>, to the study of Primordial Black Holes (PBHs) as Dark Matter (DM) candidates, deriving constraints on the abundance from observations of diffuse extragalactic <span><math><mi>γ</mi></math></span>-ray background. These results highlight the possible role of SR in providing human-interpretable, approximate analytical GBF expressions, offering a new pathway for investigating PBH as a DM candidate.</div></div>","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"50 ","pages":"Article 102078"},"PeriodicalIF":6.4,"publicationDate":"2025-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145050091","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}

引用次数: 0

Modified Kerr black holes surrounded by dark matter spike 被暗物质尖峰包围的修正克尔黑洞

IF 6.4 2区物理与天体物理

Physics of the Dark Universe Pub Date : 2025-09-09 DOI: 10.1016/j.dark.2025.102065

S. Capozziello , S. Zare , L.M. Nieto , H. Hassanabadi

{"title":"Modified Kerr black holes surrounded by dark matter spike","authors":"S. Capozziello , S. Zare , L.M. Nieto , H. Hassanabadi","doi":"10.1016/j.dark.2025.102065","DOIUrl":"10.1016/j.dark.2025.102065","url":null,"abstract":"<div><div>We study supermassive black holes (SMBH), surrounded by a dark matter (DM) spike, that can be found at the centers of Milky Way and <span><math><mtext>M87</mtext></math></span> galaxies and are accompanied by a specific kind of topological defect. The investigation is developed within the framework of Bumblebee Gravity with a global monopole (BGGM). The dark matter spike is described by a power-law density profile. Our main objective is to assess how the background arising from spontaneous Lorentz symmetry breaking and the presence of a global monopole influence the properties of the Kerr BH within the region affected by the spike. Using a spherically symmetric static BH with BGGM properties as the seed metric, we construct a non-rotating spacetime with a DM spike, resulting in a BGGM-motivated Schwarzschild-like BH by solving the modified Tolman–Oppenheimer–Volkoff equations (TOV). Next, we extend this approach to the case of a rotating spacetime resulting in the BGGM-motivated Kerr-like BH (BGMKLBH). This approach allows us to explore the spacetime structure, and the BGMKLBH shadows. Then, using available observational data for the DM spike density and considering the effects of BGGM on <span><math><msup><mrow><mtext>Sgr A</mtext></mrow><mrow><mo>∗</mo></mrow></msup></math></span> and <span><math><msup><mrow><mtext>M87</mtext></mrow><mrow><mo>∗</mo></mrow></msup></math></span> SMBHs, we analyze the shapes of their shadows and put constraints on the BGGM parameter. Thus, we infer that the BGMKLBHs could be reliable candidates for the astrophysical BHs.</div></div>","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"50 ","pages":"Article 102065"},"PeriodicalIF":6.4,"publicationDate":"2025-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145050096","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}

引用次数: 0

Black holes and gravitational waves from phase transitions in realistic models 黑洞和引力波在现实模型中的相变

IF 6.4 2区物理与天体物理

Physics of the Dark Universe Pub Date : 2025-09-08 DOI: 10.1016/j.dark.2025.102075

M. Lewicki , P. Toczek , V. Vaskonen

引用次数: 0

Inconsistency with de Sitter spacetime in a new approach to gravitational particle production 在引力粒子产生的新方法中与德西特时空的不一致性

IF 6.4 2区物理与天体物理

Physics of the Dark Universe Pub Date : 2025-09-04 DOI: 10.1016/j.dark.2025.102067

Mark P. Hertzberg , Abraham Loeb

引用次数: 0

Constant-roll inflation and primordial black holes within Barrow entropic framework 巴罗熵框架内的恒定滚动膨胀和原始黑洞

IF 6.4 2区物理与天体物理

Physics of the Dark Universe Pub Date : 2025-09-03 DOI: 10.1016/j.dark.2025.102072

Qihong Huang , Li-Yang Chen , He Huang , Bing Xu , Kaituo Zhang

{"title":"Constant-roll inflation and primordial black holes within Barrow entropic framework","authors":"Qihong Huang , Li-Yang Chen , He Huang , Bing Xu , Kaituo Zhang","doi":"10.1016/j.dark.2025.102072","DOIUrl":"10.1016/j.dark.2025.102072","url":null,"abstract":"<div><div>In this paper, starting from the modified Einstein field equations, we derive the modified scalar spectral index <span><math><msub><mrow><mi>n</mi></mrow><mrow><mi>s</mi></mrow></msub></math></span> and the modified tensor-to-scalar ratio <span><math><mi>r</mi></math></span> in Barrow entropy model, calculate their values for the power-law, periodic, and hilltop potential models, constrain the model parameter <span><math><mi>δ</mi></math></span> and the potential parameter using Planck 2018 data, and find that increasing <span><math><mi>δ</mi></math></span> causes a significant decrease in <span><math><mi>r</mi></math></span>. Then, we calculate the primordial curvature perturbation power spectra, primordial black hole (PBH) abundance, and scalar induced gravitational waves (SIGWs) for these models, finding PBH mass of approximately <span><math><mrow><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mo>−</mo><mn>12</mn></mrow></msup><msub><mrow><mi>M</mi></mrow><mrow><mo>⊙</mo></mrow></msub></mrow></math></span>, PBH abundance nearly 0.98, and the peak frequencies of SIGWs on the order <span><math><mrow><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mo>−</mo><mn>3</mn></mrow></msup><mi>Hz</mi></mrow></math></span>, indicating that these models not only generate sufficient PBHs which can contribute one-third of the dark matter content but could also be detected by next-generation missions such as LISA, Taiji, and TianQin. Subsequently, we analyze the evolution of PBHs and find that when the effective equation of state parameter evolves from <span><math><mrow><mn>1</mn><mo>/</mo><mn>3</mn></mrow></math></span> to <span><math><mrow><mo>−</mo><mn>1</mn><mo>/</mo><mn>3</mn></mrow></math></span>, the accretion mass increases to approximately <span><math><mrow><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mn>2</mn></mrow></msup><msub><mrow><mi>M</mi></mrow><mrow><mi>i</mi></mrow></msub></mrow></math></span>, while the temperature of the PBHs decreases from <span><math><mrow><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mn>4</mn></mrow></msup><mi>K</mi></mrow></math></span> to <span><math><mrow><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mn>2</mn></mrow></msup><mi>K</mi></mrow></math></span>, suggesting that PBHs exist and are detectable today.</div></div>","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"50 ","pages":"Article 102072"},"PeriodicalIF":6.4,"publicationDate":"2025-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145004447","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}

引用次数: 0

Randall–Sundrum braneworld perspectives on gravastar models: Unraveling the effects of Heintzmann metric potential 重力星模型的Randall-Sundrum膜世界视角：揭示海因茨曼度量势的影响

IF 6.4 2区物理与天体物理

Physics of the Dark Universe Pub Date : 2025-09-02 DOI: 10.1016/j.dark.2025.102073

Arfa Waseem , A. Eid , Sunaiha Naeem , Faisal Javed

{"title":"Randall–Sundrum braneworld perspectives on gravastar models: Unraveling the effects of Heintzmann metric potential","authors":"Arfa Waseem , A. Eid , Sunaiha Naeem , Faisal Javed","doi":"10.1016/j.dark.2025.102073","DOIUrl":"10.1016/j.dark.2025.102073","url":null,"abstract":"<div><div>This investigation delves into the characteristics of gravastars within the context of braneworld models, particularly a higher dimensional warped spacetime proposed by Randall and Sundrum, incorporating a favorable brane tension. A novel approach is adopted using the temporal component of Heintzmann ansatz that guarantees stability and avoids the formation of singularities. In accordance with the hypothesis proposed by Mazur and Mottola concerning the nature of gravastars, we determine the fundamental parameters by enforcing interface constraints relevant to a space devoid of matter, deliberately neglecting the influence of a cosmological constant. The proposed model includes an external region modeled by a relativistic fluid, with an inner core consisting of exotic matter. Through this framework, we explore the gravitational properties of gravastars, including the total mass, the energy content within the outer shell, thermodynamic quantities such as entropy, gravitational redshift at the boundary and the distribution of mass within the central core and the surrounding envelope.</div></div>","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"50 ","pages":"Article 102073"},"PeriodicalIF":6.4,"publicationDate":"2025-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145020456","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}

引用次数: 0

Oscillatory motion and QPO signatures around rotating short-hairy black holes: Bridging theory and observation 旋转短毛黑洞周围的振荡运动和QPO特征：桥接理论与观测

IF 6.4 2区物理与天体物理

Physics of the Dark Universe Pub Date : 2025-09-01 DOI: 10.1016/j.dark.2025.102071

Allah Ditta , Asifa Ashraf , S.K. Maurya , Akram Ali , Asalkhon Alimova , Farruh Atamurotov

{"title":"Oscillatory motion and QPO signatures around rotating short-hairy black holes: Bridging theory and observation","authors":"Allah Ditta , Asifa Ashraf , S.K. Maurya , Akram Ali , Asalkhon Alimova , Farruh Atamurotov","doi":"10.1016/j.dark.2025.102071","DOIUrl":"10.1016/j.dark.2025.102071","url":null,"abstract":"<div><div>Current study deals with the test particles dynamics around a rotating short-hairy black hole. We explore how the parameter related to SH affect the motion of particles. This solution is characterized by parameters such as the black hole mass <span><math><mi>M</mi></math></span>, rotation parameter <span><math><mi>a</mi></math></span>, short hairy <span><math><mi>q</mi></math></span> that measures the strength of the hair and a parameter <span><math><mi>α</mi></math></span>. We derive analytical solutions for the radial profiles of the particular energy and the particular <span><math><mi>L</mi></math></span> for stable circular orbits in the equatorial plane. In addition, using the <span><math><msub><mrow><mi>V</mi></mrow><mrow><mi>e</mi><mi>f</mi><mi>f</mi></mrow></msub></math></span> approach, we examine the stability of circular equatorial orbits and the forces that affect the particles. The radial and latitudinal harmonic oscillation frequencies are calculated as functions of the mass <span><math><mi>M</mi></math></span>, parameter <span><math><mi>α</mi></math></span>, SH parameter <span><math><mi>q</mi></math></span>, and rotation parameter <span><math><mi>a</mi></math></span>. We also examine the main features of quasi-periodic oscillations of test particles in very close stable circular orbits. Specifically, we study precession effects such as the periastron precession and Lense–Thirring effect. We compare the results we obtained with those that correspond to the Kerr–Newman black hole. Our findings show that the motion of particles around the black hole is significantly influenced by the parameters of the black hole model.</div></div>","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"50 ","pages":"Article 102071"},"PeriodicalIF":6.4,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145004448","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}

引用次数: 0

Testing linear non-minimal coupling in f(Q,T) gravity using X-ray binary pulsars constrained by NICER observations 利用NICER观测约束的x射线双脉冲星测试f（Q，T）重力中的线性非极小耦合

IF 6.4 2区物理与天体物理

Physics of the Dark Universe Pub Date : 2025-09-01 DOI: 10.1016/j.dark.2025.102055

A. Errehymy , S.K. Maurya , O. Donmez , Z. Umbetova , J. Rayimbaev , M. Motawi Khashan , Mohamed R. Eid

引用次数: 0