Physics of the Dark Universe最新文献

{"title":"Perfect fluid dynamics with observational constraint in the framework of f(T) gravity","authors":"D.D. Pawar ,&nbsp;P.S. Gaikwad ,&nbsp;Shah Muhammad ,&nbsp;Euaggelos E. Zotos","doi":"10.1016/j.dark.2025.101821","DOIUrl":"10.1016/j.dark.2025.101821","url":null,"abstract":"<div><div>In this study, we explore cosmological models within the framework of <span><math><mrow><mi>f</mi><mrow><mo>(</mo><mi>T</mi><mo>)</mo></mrow></mrow></math></span> gravity by utilizing the energy–momentum tensor for a perfect fluid to solve the corresponding field equations. We derive key cosmological parameters, including the Hubble parameter <span><math><mi>H</mi></math></span>. Parameter constraints were applied using the <span><math><msup><mrow><mi>R</mi></mrow><mrow><mn>2</mn></mrow></msup></math></span> test, resulting in best-fit values of <span><math><mrow><mi>β</mi><mo>=</mo><mn>108</mn><mo>.</mo><mn>5</mn><msubsup><mrow><mn>1</mn></mrow><mrow><mo>−</mo><mn>0</mn><mo>.</mo><mn>40</mn></mrow><mrow><mo>+</mo><mn>0</mn><mo>.</mo><mn>41</mn></mrow></msubsup></mrow></math></span> and <span><math><mrow><msub><mrow><mi>ξ</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>=</mo><mo>−</mo><msubsup><mrow><mn>0</mn><mo>.</mo><mn>14717</mn></mrow><mrow><mo>−</mo><mn>0</mn><mo>.</mo><mn>00096</mn></mrow><mrow><mo>+</mo><mn>0</mn><mo>.</mo><mn>00094</mn></mrow></msubsup></mrow></math></span>, with a strong alignment with the <span><math><mi>Λ</mi></math></span>CDM model (<span><math><mrow><msup><mrow><mi>R</mi></mrow><mrow><mn>2</mn></mrow></msup><mo>=</mo><mn>0</mn><mo>.</mo><mn>9280</mn></mrow></math></span>; RMSE = 11.4068). The deceleration parameter, calculated in terms of cosmic time and redshift, indicates a transition from deceleration to acceleration, consistent with current observations of an accelerating universe. Additionally, we examined the pressure <span><math><mi>p</mi></math></span>, energy density <span><math><mi>ρ</mi></math></span>, and equation of state parameter <span><math><mi>ω</mi></math></span> for two specific models: Model-I for <span><math><mrow><mi>f</mi><mrow><mo>(</mo><mi>T</mi><mo>)</mo></mrow><mo>=</mo><mi>λ</mi><mi>T</mi></mrow></math></span> and Model-II for <span><math><mrow><mi>f</mi><mrow><mo>(</mo><mi>T</mi><mo>)</mo></mrow><mo>=</mo><mi>T</mi><mo>+</mo><mi>β</mi><msup><mrow><mi>T</mi></mrow><mrow><mn>2</mn></mrow></msup></mrow></math></span>. The Om diagnostic plotted against redshift for <span><math><msub><mrow><mi>ξ</mi></mrow><mrow><mn>1</mn></mrow></msub></math></span> shows that <span><math><mrow><mi>Ω</mi><mrow><mo>(</mo><mi>z</mi><mo>)</mo></mrow></mrow></math></span> stabilizes around 0.3 after a slight deviation at <span><math><mrow><mi>z</mi><mo>≈</mo><mn>0</mn></mrow></math></span>, with a narrow uncertainty band. The model closely aligns with <span><math><mi>Λ</mi></math></span>CDM at higher redshifts. The pair of statefinder diagnostics <span><math><mi>r</mi></math></span> vs. <span><math><mi>s</mi></math></span> is also discussed, and our model for <span><math><mrow><mrow><mo>(</mo><mi>r</mi><mo>,</mo><mi>s</mi><mo>)</mo></mrow><mo>=</mo><mrow><mo>(</mo><mn>1</mn><mo>,</mo><mn>0</mn><mo>)</mo></mrow></mrow></math></span> represents the <span><math><mi>Λ</mi></math></span>CDM model.</div></div>","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"47 ","pages":"Article 101821"},"PeriodicalIF":5.0,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143100689","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}

{"title":"On Wigner degeneracy in Elko theory: Hermiticity and dark matter","authors":"Gabriel Brandão de Gracia ,&nbsp;Roldão da Rocha ,&nbsp;Rodolfo José Bueno Rogerio ,&nbsp;Cheng-Yang Lee","doi":"10.1016/j.dark.2024.101774","DOIUrl":"10.1016/j.dark.2024.101774","url":null,"abstract":"<div><div>In this paper, we provide a set of Hermitian interactions for quantum fields based on Elko, considering the recent achievements concerning the most general form of singular spinors and Wigner degeneracy. We consider Hermiticity and renormalizability a criterion to define the derivative Elko–Higgs interaction as the suitable candidate for a dark coupling. Then, the free parameters of the model are fixed by cosmological constraints on the dark matter abundance and limits on the electron-dark matter scattering mediated by the Higgs.</div></div>","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"47 ","pages":"Article 101774"},"PeriodicalIF":5.0,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143099711","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}

{"title":"Testing regular scale-dependent black hole space time using particle dynamics: Shadow and gravitational weak lensing","authors":"Tolibjon Ibrokhimov ,&nbsp;Ziyodulla Turakhonov ,&nbsp;Farruh Atamurotov ,&nbsp;Ahmadjon Abdujabbarov ,&nbsp;Koblandy Yerzhanov ,&nbsp;Gulnur Bauyrzhan ,&nbsp;Alisher Abduvokhidov","doi":"10.1016/j.dark.2024.101778","DOIUrl":"10.1016/j.dark.2024.101778","url":null,"abstract":"<div><div>In this study, we examine the effects of weak gravitational lensing and determine the shadow radius around black holes within the regular scale-dependent spacetime, also accounting for both uniform and nonuniform plasma models. By analyzing various gravitational lens, we compare corrections to vacuum lensing due to gravitational effects within plasma and plasma inhomogeneity, finding that these effects could be observed in hot gas within galaxy clusters. Starting with the orbits of photons around a regular scale-dependent black hole, we investigate the shadow and weak gravitational lensing phenomena. Utilizing observational data from the Event Horizon Telescope (EHT) for SgrA*, we constrain on parameter within regular scale-dependent gravity. To connect our findings to observations, we examine the magnification and positioning of lensed images, along with the weak deflection angle and magnification for sources near different galaxies.</div></div>","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"47 ","pages":"Article 101778"},"PeriodicalIF":5.0,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143100214","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}

{"title":"Exploring perfect fluid accretion onto quantum-corrected Reissner–Nordstrom black hole","authors":"A. Bukhari ,&nbsp;Ghulam Abbas ,&nbsp;H. Rehman ,&nbsp;Asifa Ashraf ,&nbsp;Assmaa Abd-Elmonem ,&nbsp;Nagat A.A. Suoliman","doi":"10.1016/j.dark.2024.101794","DOIUrl":"10.1016/j.dark.2024.101794","url":null,"abstract":"<div><div>The current study examines astrophysical accretion near a static and spherically symmetric, quantum-corrected charged black hole. Furthermore, the analysis focuses on fluid dynamics in the vicinity of gravitationally quantum-corrected Reissner–Nordstrom Anti-de Sitter black hole for the polytropic and isothermal forms, categorized by their equation of state. We utilized the Hamiltonian dynamical procedure to explore the behavior of the specified fluids. As part of the investigation, the sonic or critical points are identified, revealing key transitions in fluid flow. Also, we have presented the fluid behavior in a closed form through a graphical representation. The results of this research help us to analyze the accretion phenomenon within the effects of quantum gravity.</div></div>","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"47 ","pages":"Article 101794"},"PeriodicalIF":5.0,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143100217","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}

{"title":"Properties of an axisymmetric Lorentzian non-commutative black hole","authors":"A.A. Araújo Filho ,&nbsp;J.R. Nascimento ,&nbsp;A. Yu. Petrov ,&nbsp;P.J. Porfírio ,&nbsp;Ali Övgün","doi":"10.1016/j.dark.2024.101796","DOIUrl":"10.1016/j.dark.2024.101796","url":null,"abstract":"<div><div>In this work, we start by examining a spherically symmetric black hole within the framework of non-commutative geometry and apply a modified Newman–Janis method to obtain a new rotating solution. We then investigate its consequences, focusing on the horizon structure, ergospheres, and the black hole’s angular velocity. Following this, a detailed thermodynamic analysis is performed, covering surface gravity, <em>Hawking</em> temperature, entropy, and heat capacity. We also study geodesic motion, with particular emphasis on null geodesics and their associated radial accelerations. Additionally, the photon sphere and the resulting black hole shadows are explored. Finally, we compute the <em>quasinormal</em> modes for scalar perturbations using the 6th-order WKB approximation.</div></div>","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"47 ","pages":"Article 101796"},"PeriodicalIF":5.0,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143100218","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}

{"title":"Cosmological dynamics and thermodynamic behavior in f(Q,C) gravity: An analytical and observational approach","authors":"Amit Samaddar,&nbsp;S. Surendra Singh","doi":"10.1016/j.dark.2024.101792","DOIUrl":"10.1016/j.dark.2024.101792","url":null,"abstract":"&lt;div&gt;&lt;div&gt;In this study, we investigate a Friedmann–Robertson–Walker (FRW) cosmological model within the context of &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;f&lt;/mi&gt;&lt;mrow&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mi&gt;Q&lt;/mi&gt;&lt;mo&gt;,&lt;/mo&gt;&lt;mi&gt;C&lt;/mi&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/mrow&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; gravity, where &lt;span&gt;&lt;math&gt;&lt;mi&gt;Q&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt; represents the non-metricity scalar and &lt;span&gt;&lt;math&gt;&lt;mi&gt;C&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt; denotes a boundary term. We explore two specific forms of &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;f&lt;/mi&gt;&lt;mrow&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mi&gt;Q&lt;/mi&gt;&lt;mo&gt;,&lt;/mo&gt;&lt;mi&gt;C&lt;/mi&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/mrow&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;: &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;f&lt;/mi&gt;&lt;mrow&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mi&gt;Q&lt;/mi&gt;&lt;mo&gt;,&lt;/mo&gt;&lt;mi&gt;C&lt;/mi&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/mrow&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mi&gt;Q&lt;/mi&gt;&lt;mo&gt;+&lt;/mo&gt;&lt;mi&gt;α&lt;/mi&gt;&lt;mi&gt;Q&lt;/mi&gt;&lt;mo&gt;+&lt;/mo&gt;&lt;mi&gt;β&lt;/mi&gt;&lt;mi&gt;C&lt;/mi&gt;&lt;mo&gt;log&lt;/mo&gt;&lt;mi&gt;C&lt;/mi&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; and &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;f&lt;/mi&gt;&lt;mrow&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mi&gt;Q&lt;/mi&gt;&lt;mo&gt;,&lt;/mo&gt;&lt;mi&gt;C&lt;/mi&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/mrow&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mi&gt;Q&lt;/mi&gt;&lt;mo&gt;+&lt;/mo&gt;&lt;mi&gt;α&lt;/mi&gt;&lt;mi&gt;Q&lt;/mi&gt;&lt;mo&gt;+&lt;/mo&gt;&lt;mfrac&gt;&lt;mrow&gt;&lt;mi&gt;β&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;C&lt;/mi&gt;&lt;/mrow&gt;&lt;/mfrac&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;, with &lt;span&gt;&lt;math&gt;&lt;mi&gt;α&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt; and &lt;span&gt;&lt;math&gt;&lt;mi&gt;β&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt; as free parameters. Utilizing a parametric form of the Hubble parameter, &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;H&lt;/mi&gt;&lt;mrow&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mi&gt;z&lt;/mi&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/mrow&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;H&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mfenced&gt;&lt;mrow&gt;&lt;mi&gt;σ&lt;/mi&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mrow&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;mo&gt;+&lt;/mo&gt;&lt;mi&gt;z&lt;/mi&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/mrow&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;3&lt;/mn&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;mo&gt;+&lt;/mo&gt;&lt;mi&gt;δ&lt;/mi&gt;&lt;mo&gt;+&lt;/mo&gt;&lt;mrow&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mi&gt;σ&lt;/mi&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mi&gt;δ&lt;/mi&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/mrow&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mrow&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;mo&gt;+&lt;/mo&gt;&lt;mi&gt;z&lt;/mi&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/mrow&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;/mrow&gt;&lt;/mfenced&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mfrac&gt;&lt;mrow&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/mrow&gt;&lt;/mfrac&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;, we fit the model by employing the MCMC technique to observational data, which includes Hubble, Hubble+BAO and Hubble+Pantheon datasets. Our findings show that the energy density increases over time and the deceleration parameter &lt;span&gt;&lt;math&gt;&lt;mi&gt;q&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt; transitions from positive to &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;, which indicates an accelerated expansion of Universe that is similar to &lt;span&gt;&lt;math&gt;&lt;mi&gt;Λ&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt;CDM. The equation of state parameter &lt;span&gt;&lt;math&gt;&lt;mi&gt;ω&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt; also approaches to &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; that confirms this behavior. We also examine energy conditions and it is observed that our model violates the strong energy condition. Statefinder diagnostics indicate a progression from quintessence to &lt;span&gt;&lt;math&gt;&lt;mi&gt;Λ&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt;CDM which is consistent with current observations. Furthermore, thermodynamic analysis demonstrates that entropy density increases with redshift that implies the validation of the second law of thermodynamics. Overall, our &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;f&lt;/mi&gt;&lt;mrow&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mi&gt;Q&lt;/mi&gt;&lt;mo&gt;,&lt;/mo&gt;&lt;mi&gt;C&lt;/mi&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/mrow&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; model provides a detailed ","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"47 ","pages":"Article 101792"},"PeriodicalIF":5.0,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143100219","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}

{"title":"Traversable Wormholes and their shadows in 4D Einstein–Gauss–Bonnet Gravity: An analytic description","authors":"Madhukrishna Chakraborty ,&nbsp;Subenoy Chakraborty","doi":"10.1016/j.dark.2024.101793","DOIUrl":"10.1016/j.dark.2024.101793","url":null,"abstract":"<div><div>Einstein–Gauss–Bonnet gravity (EGB) in 4D started its journey in 2020, after a regularization on <span><math><mrow><mi>D</mi><mo>→</mo><mn>4</mn></mrow></math></span> limit of EGB gravity considering a rescaled GB coupling constant as <span><math><mfrac><mrow><mi>α</mi></mrow><mrow><mrow><mo>(</mo><mi>D</mi><mo>−</mo><mn>4</mn><mo>)</mo></mrow></mrow></mfrac></math></span> and taking the limit <span><math><mrow><mi>D</mi><mo>→</mo><mn>4</mn></mrow></math></span> by Glavan and Lin. As a result, the regularized 4D gravity theory have non trivial gravitational dynamics. The present work is an attempt to obtain solutions of 4D EGB theory in the background of static spherically symmetric space–time and it has been examined whether they correspond to any possible traversable Wormhole (WH). For matter field, isotropic/ anisotropic fluid and various possible equation of state are considered. Embedding diagrams are analyzed and energy conditions are examined for the WH solutions. Finally, feasible WH shadows have been determined in EGB theory.</div></div>","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"47 ","pages":"Article 101793"},"PeriodicalIF":5.0,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143100220","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}

{"title":"Thermal fluctuations and greybody factor of loop quantum black holes","authors":"Faisal Javed ,&nbsp;Sulaman Shaukat ,&nbsp;G. Mustafa ,&nbsp;Allah Ditta ,&nbsp;Bander Almutairi","doi":"10.1016/j.dark.2025.101826","DOIUrl":"10.1016/j.dark.2025.101826","url":null,"abstract":"<div><div>This research investigates the thermal fluctuations and greybody factor of a (3+1)-dimensional black hole within the framework of loop quantum gravity, incorporating higher-order corrections. Our findings indicate that the event horizons are significantly influenced by the loop quantum black hole parameters causing the event horizon to shift outward from the center. We observe the higher-order corrected entropy and respective physical quantities like internal energy, Helmholtz free energy, and Gibbs free energy are evaluated. It reveals that larger black holes tend to have lower values of corrected energies suggesting greater thermodynamic stability. Using the Klein–Gordon equation transformed into a Schrödinger wave equation via tortoise coordinates, we derive the effective potential and analyze its behavior relative to key parameters, including the black hole parameters, and angular momentum. The effective potential exhibits maximum values at smaller horizon radii, decreasing for more massive black holes, highlighting the complex relationship between mass and horizon structure. By solving the radial equation, we can derive two solutions corresponding to the event and cosmic horizons. Using these two solutions in the intermediate regime, we can ascertain the greybody component and its associated behavior. Additionally, raising the quantum parameter also results in a drop in the rate of absorption, demonstrating that the presence of a quantum parameter lowers the absorption rate of Schwarzschild black hole. These intricate dynamics underscore the significant role of loop quantum gravity parameters in shaping black hole thermodynamics and point to potential avenues for future research into their observational implications.</div></div>","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"47 ","pages":"Article 101826"},"PeriodicalIF":5.0,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143100225","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}

{"title":"Thermodynamic topology and photon spheres of dirty black holes within non-extensive entropy","authors":"Saeed Noori Gashti ,&nbsp;Behnam Pourhassan ,&nbsp;İzzet Sakallı ,&nbsp;Aram Bahroz Brzo","doi":"10.1016/j.dark.2025.101833","DOIUrl":"10.1016/j.dark.2025.101833","url":null,"abstract":"<div><div>In this paper, we investigate the intricate thermodynamic topology of static dirty black holes within the framework of non-extensive entropy models, including Rényi, Sharma–Mittal, and Barrow statistics. Employing the generalized off-shell Helmholtz free energy method, we rigorously compute the thermodynamic topology of these black holes, deriving their topological classifications for each entropy model. Our analysis reveals that parameters such as the Dilaton parameter <span><math><msup><mrow><mi>η</mi></mrow><mrow><mn>2</mn></mrow></msup></math></span>, the non-extensive parameter <span><math><mi>λ</mi></math></span> of Rényi entropy, and the parameters <span><math><mi>α</mi></math></span> and <span><math><mi>β</mi></math></span> of Sharma–Mittal entropy, along with the parameter <span><math><mi>δ</mi></math></span> of Barrow entropy, have a substantial impact on the topological charges of black holes. These findings provide new insights into the topological classifications, underscoring the complex interplay between different entropy models and their influence on black hole thermodynamics. Additionally, when the non-extensive parameter approaches zero, our results reduce to the Bekenstein–Hawking entropy structure, which yields distinct results and introduces new topological classifications, enriching the understanding of black hole thermodynamics. Through detailed analysis and graphical illustrations, we demonstrate the effects of varying these parameters on the topological structure of black holes. Our study offers significant insights into the thermodynamic properties and phase transitions of black holes, advancing our comprehension of their underlying topological nature.</div></div>","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"47 ","pages":"Article 101833"},"PeriodicalIF":5.0,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143100231","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}

{"title":"Neutrino masses from large-scale structures: Future sensitivity and theory dependence","authors":"Davide Racco ,&nbsp;Pierre Zhang ,&nbsp;Henry Zheng","doi":"10.1016/j.dark.2024.101803","DOIUrl":"10.1016/j.dark.2024.101803","url":null,"abstract":"<div><div>In the incoming years, cosmological surveys aim at measuring the sum of neutrino masses <span><math><mrow><mi>Σ</mi><msub><mrow><mi>m</mi></mrow><mrow><mi>ν</mi></mrow></msub></mrow></math></span>, complementing the determination of their mass ordering from laboratory experiments. In order to assess the full potential of large-scale structures (LSS), we employ state-of-the-art predictions from the effective field theory of LSS (EFTofLSS) at one loop to perform Fisher forecasts on the sensitivity (combining power spectrum and bispectrum) of ongoing and future surveys (DESI, MegaMapper) in combination with CMB measurements (Planck, Litebird and Stage-4). We find that the 1<span><math><mi>σ</mi></math></span> sensitivity on <span><math><mrow><mi>Σ</mi><msub><mrow><mi>m</mi></mrow><mrow><mi>ν</mi></mrow></msub></mrow></math></span> is expected to be 15 meV with Planck+DESI, and 7 meV with S4+MegaMapper, where <span><math><mrow><mo>∼</mo><mn>10</mn><mtext>%</mtext></mrow></math></span> and 30% of the constraints are brought by the one-loop bispectrum respectively. To understand how robust are these bounds, we explore how they are relaxed when considering extensions to the standard model, dubbed ‘new physics’. We find that the shift induced on <span><math><mrow><mi>Σ</mi><msub><mrow><mi>m</mi></mrow><mrow><mi>ν</mi></mrow></msub></mrow></math></span> by a <span><math><mrow><mn>1</mn><mi>σ</mi></mrow></math></span> shift on new physics parameters (we consider extra relativistic species, neutrino self-interactions, curvature or a time-evolving electron mass) could be <span><math><mrow><mi>O</mi><mrow><mo>(</mo><mn>10</mn><mo>)</mo></mrow></mrow></math></span> meV for Planck+DESI, but it will be suppressed down to <span><math><mrow><mi>O</mi><mrow><mo>(</mo><mn>1</mn><mo>)</mo></mrow></mrow></math></span> meV in S4+MegaMapper. Our study highlights the quantitative impact of including the bispectrum at one loop in the EFTofLSS, and the robustness of the sensitivity to <span><math><mrow><mi>Σ</mi><msub><mrow><mi>m</mi></mrow><mrow><mi>ν</mi></mrow></msub></mrow></math></span> against potential new physics thanks to the synergy of cosmological probes.</div></div>","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"47 ","pages":"Article 101803"},"PeriodicalIF":5.0,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143100682","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}