Physics of the Dark Universe最新文献

{"title":"Testing of rotating Einstein-Yang–Mills-Higgs black hole through QPOs","authors":"Asifa Ashraf ,&nbsp;Faisal Javed ,&nbsp;S.K. Maurya ,&nbsp;Phongpichit Channuie ,&nbsp;Arzu Cilli ,&nbsp;Ertan Güdekli","doi":"10.1016/j.dark.2025.101853","DOIUrl":"10.1016/j.dark.2025.101853","url":null,"abstract":"<div><div>We investigate the influence of model parameters on the orbital and epicyclic motion of test particles around a spinning Einstein-Yang–Mills-Higgs black hole. A black hole having four defining parameters is its mass <span><math><mi>M</mi></math></span>, its rotation parameter <span><math><mi>a</mi></math></span>, a constant, <span><math><mi>β</mi></math></span> and the theory parameter <span><math><mi>B</mi></math></span>. Formulas for the specific energy and angular momentum of the circular orbits in an equatorial plane are derived analytically. The stability of the spherical equatorial orbit is also examined using the effective potential method. We obtain analytical formulas for the particle frequencies of the radial, vertical, and orbital oscillations in relation to the properties of the black hole model under consideration. The main characteristics of quasi-periodic oscillations close to the stable circular orbits are discussed. Furthermore, we examine the precessions of Periastron and Lense-Thirring. It is concluded that the parameters of the consider black hole model strongly influence the motion of the particles around the black hole.</div></div>","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"48 ","pages":"Article 101853"},"PeriodicalIF":5.0,"publicationDate":"2025-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143387318","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":"A new generic class of charged stellar structure in extended teleparallel gravity","authors":"M.R. Shahzad ,&nbsp;Liaba Fakhar ,&nbsp;H. Nazar ,&nbsp;Asifa Ashraf ,&nbsp;Awatef Abidi","doi":"10.1016/j.dark.2025.101851","DOIUrl":"10.1016/j.dark.2025.101851","url":null,"abstract":"<div><div>In the present work, we proposed a new class of well-behaved charged spherical stellar models in <span><math><mrow><mi>f</mi><mrow><mo>(</mo><mi>T</mi><mo>)</mo></mrow></mrow></math></span> gravity. A short review of the formulation of field equations is presented by taking the linear model of torsion function as <span><math><mrow><mi>f</mi><mrow><mo>(</mo><mi>T</mi><mo>)</mo></mrow><mo>=</mo><mi>α</mi><mi>T</mi><mo>+</mo><mi>β</mi></mrow></math></span>, where <span><math><mi>α</mi></math></span> is the coupling parameter of the theory, which is responsible for the deviation from the slandered General Relativity (<span><math><mrow><mi>G</mi><mi>R</mi></mrow></math></span>) theory and explains the matter field’s tendency to couple with geometry. To obtain a realistic solution to the established field equations we have selected a well-behaved ansatz of generalized Tolman–Kuchowicz (GTK) potential functions and the well-studied MIT bag model equation of state. As an external geometry, we include the Reissner–Nordström solution for matching conditions to identify the unknown constants resulting from the <span><math><mrow><mi>G</mi><mi>T</mi><mi>K</mi></mrow></math></span> metric. The proposed model undergoes comprehensive validation to confirm its viability as a physically consistent compact object within the framework of <span><math><mrow><mi>f</mi><mrow><mo>(</mo><mi>T</mi><mo>)</mo></mrow></mrow></math></span> gravity. We meticulously analyze two critical parameters: <span><math><mi>α</mi></math></span> and <span><math><mi>n</mi></math></span>, examining their effects on the mass, radius, and overall stability of the stellar configuration. Our investigations reveal that the model demonstrates stable behavior, devoid of singularities, and successfully accounts for a diverse array of observed compact objects in astrophysics. This thorough examination ensures that the model adheres to necessary physical criteria, reinforcing its potential applicability to understanding compact star phenomena.</div></div>","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"48 ","pages":"Article 101851"},"PeriodicalIF":5.0,"publicationDate":"2025-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143387317","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":"Probing gravitational baryogenesis phenomenon in specific modified gravity","authors":"A.D. Alruwaili ,&nbsp;N. Azhar ,&nbsp;A. Jawad ,&nbsp;A.B. Albarrak","doi":"10.1016/j.dark.2025.101842","DOIUrl":"10.1016/j.dark.2025.101842","url":null,"abstract":"<div><div>In this research, we investigate the phenomenon of gravitational baryogenesis and generalized gravitational baryogenesis within the framework of <span><math><mrow><mi>f</mi><mrow><mo>(</mo><mi>Q</mi><mo>,</mo><mi>B</mi><mo>)</mo></mrow></mrow></math></span> gravity where <span><math><mi>Q</mi></math></span> expresses the non-metricity scalar and <span><math><mi>B</mi></math></span> is the boundary term. To explore this mechanism, we utilize four distinct minimal and non-minimal <span><math><mrow><mi>f</mi><mrow><mo>(</mo><mi>Q</mi><mo>,</mo><mi>B</mi><mo>)</mo></mrow></mrow></math></span> models and analyze the evolution of the baryon to entropy ratio in relation to a scale factor in the form of a power-law ( <span><math><mrow><mi>a</mi><mo>=</mo><mi>Υ</mi><mspace></mspace><msup><mrow><mi>t</mi></mrow><mrow><mi>γ</mi></mrow></msup></mrow></math></span>, where <span><math><mi>Υ</mi></math></span> and <span><math><mi>γ</mi></math></span> are nonzero constants). By studying the CP-violating interaction terms <span><math><mrow><msub><mrow><mi>∂</mi></mrow><mrow><mi>μ</mi></mrow></msub><mrow><mo>(</mo><mi>Q</mi><mo>+</mo><mi>B</mi><mo>)</mo></mrow></mrow></math></span> and <span><math><mrow><msub><mrow><mi>∂</mi></mrow><mrow><mi>μ</mi></mrow></msub><mi>f</mi><mrow><mo>(</mo><mi>Q</mi><mo>+</mo><mi>B</mi><mo>)</mo></mrow></mrow></math></span>, we derive expressions for the baryon asymmetry and examine its behavior across different cosmological epochs. The results obtained from all four models demonstrate compatibility with current observational data on baryon asymmetry, suggesting that <span><math><mrow><mi>f</mi><mrow><mo>(</mo><mi>Q</mi><mo>,</mo><mi>B</mi><mo>)</mo></mrow></mrow></math></span> gravity offer a robust explanation for the matter–antimatter imbalance in the universe. Our findings reinforce the potential of this modified gravity theory to extend the understanding of baryogenesis beyond the scope of standard models, offering new insights into early universe cosmology and the mechanisms driving the generation of baryon asymmetry.</div></div>","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"48 ","pages":"Article 101842"},"PeriodicalIF":5.0,"publicationDate":"2025-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143369841","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":"Impact of modified Chaplygin gas on electrically charged thin-shell wormhole models","authors":"M. Yousaf,&nbsp;H. Asad","doi":"10.1016/j.dark.2025.101841","DOIUrl":"10.1016/j.dark.2025.101841","url":null,"abstract":"<div><div>In this study, the possibility of constructing wormhole geometries is explored within the framework of <span><math><mrow><mi>f</mi><mrow><mo>(</mo><mi>R</mi><mo>,</mo><mi>T</mi><mo>)</mo></mrow></mrow></math></span> gravity, where <span><math><mi>R</mi></math></span> is Ricci scalar and <span><math><mi>T</mi></math></span> represents the trace of the energy–momentum tensor. We employ the Visser cut-and-paste technique to construct thin-shell wormholes by joining two identical copies of the Reissner-Nordström (RN) spacetime which allows the formulation of wormhole geometries by introducing a throat, the boundary of the two spacetime copies, where the stress–energy tensor components are determined using the Lanczos equations. To derive wormhole solutions, our analyses focus on a static, spherically symmetric spacetime and incorporate the modified Chaplygin gas (MCG) equation of state (EoS) as a source of exotic matter. The dynamical equation governing the system is examined under the assumption of small linear perturbations around a static equilibrium state within an isotropic background which is critical in assessing the stability of the wormhole configurations. We present our findings theoretically and graphically, highlighting the behavior of wormhole solutions for various parametric choices of the <span><math><mrow><mi>f</mi><mrow><mo>(</mo><mi>R</mi><mo>,</mo><mi>T</mi><mo>)</mo></mrow></mrow></math></span> model and the EoS. The results indicate that distinct parameters set yield stable and unstable wormhole solutions, demonstrating the feasibility of maintaining traversable wormhole geometries in this modified gravity framework. Our considered minimally coupling <span><math><mrow><mi>f</mi><mrow><mo>(</mo><mi>R</mi><mo>,</mo><mi>T</mi><mo>)</mo></mrow></mrow></math></span> gravity model supports a variety of wormhole configurations, some of which can achieve stability under linear perturbations. These findings contribute to the broader understanding of exotic structures in modified theories of gravity and their astrophysical implications.</div></div>","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"48 ","pages":"Article 101841"},"PeriodicalIF":5.0,"publicationDate":"2025-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143369840","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":"The dynamics of cosmic evolution: Insights from bouncing cosmology","authors":"M. Sharif ,&nbsp;M. Zeeshan Gul ,&nbsp;Ahmad Nawaz","doi":"10.1016/j.dark.2025.101839","DOIUrl":"10.1016/j.dark.2025.101839","url":null,"abstract":"<div><div>The primary aim of this work is to explore feasible bouncing cosmological solutions in the framework of <span><math><mrow><mi>f</mi><mrow><mo>(</mo><mi>Q</mi><mo>,</mo><mi>C</mi><mo>)</mo></mrow></mrow></math></span> gravity, where <span><math><mi>Q</mi></math></span> denotes non-metricity and <span><math><mi>C</mi></math></span> indicates the boundary term. To achieve this, we analyze the dynamics of a Bianchi type-I spacetime with perfect fluid distribution. We consider various functional forms of <span><math><mrow><mi>f</mi><mrow><mo>(</mo><mi>Q,C</mi><mo>)</mo></mrow></mrow></math></span> theory to assess how this modified gravity framework influences cosmic evolution. Additionally, we examine the dynamics of different cosmological parameters to explore non-singular bounce solutions. We also use linear perturbation to study the stability analysis. Our findings reveal the breach of the null energy conditions, which is required for the existence of viable bounce solutions. The equation of state parameter demonstrates either a quintessence phase or a phantom regime of the universe, demonstrating that the cosmos is undergoing accelerating expansion. This gravitational framework presents a promising alternative to the standard cosmological model, presenting an innovative viewpoint on gravitational interactions and the dynamics of the early universe.</div></div>","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"48 ","pages":"Article 101839"},"PeriodicalIF":5.0,"publicationDate":"2025-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143349147","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":"Running Hubble constant: Evolutionary Dark Energy","authors":"G. Montani ,&nbsp;N. Carlevaro ,&nbsp;M.G. Dainotti","doi":"10.1016/j.dark.2025.101847","DOIUrl":"10.1016/j.dark.2025.101847","url":null,"abstract":"<div><div>We discuss an evolutionary dark energy model, based on the presence of non-equilibrium effects on the dark energy constituents, which are described via a bulk viscosity contribution. We implement the proposed dynamics by the analysis of the 40-bins Type Ia Supernovae (SNe) Pantheon sample data, in order to outline the existence of a running Hubble constant with the redshift. Via a fitting procedure, we determine the value of the additional parameter that our model possesses with respect a standard <span><math><mi>Λ</mi></math></span> Cold Dark Matter (<span><math><mi>Λ</mi></math></span>CDM) scenario. As important result, the evolutionary dark energy proposal seems more appropriate to describe the binned SN analysis with respect to the <span><math><mi>Λ</mi></math></span>CDM Hubble parameter, i.e. a non running value for the Hubble constant over the bins.</div></div>","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"48 ","pages":"Article 101847"},"PeriodicalIF":5.0,"publicationDate":"2025-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143350671","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":"Role of polytropic equation of state through structure scalars in the complex self-gravitating systems","authors":"Bander Almutairi ,&nbsp;M.M.M. Nasir ,&nbsp;T. Ganesan","doi":"10.1016/j.dark.2025.101835","DOIUrl":"10.1016/j.dark.2025.101835","url":null,"abstract":"<div><div>In this article, our aim is to study a novel approach to comprehend the complexity of gravitational objects within the background of polytropic equation of state and Einstein-Gauss–Bonnet approach. Here, we examine the role of the complexity factor in determining whether a system becomes complex or simple. We consider spherically symmetric line element with anisotropic and nonhomogeneous fluid configuration. These scalar parameters are used to examine the characteristic of physical variables, in this way, we choose one scalars as the complexity factor, following Herrera’s approach (Herrera, 2018). In order to find the structure scalars, we introduce the basic formulation of the Riemann tensor and two distinct mass approaches that address the entire energy budget of the system. In order to find the solution of the field equation, two different models are used with the help of vanishing complexity condition.</div></div>","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"48 ","pages":"Article 101835"},"PeriodicalIF":5.0,"publicationDate":"2025-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143312478","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 perturbations in a generalised axion-like dark energy model","authors":"Carlos G. Boiza ,&nbsp;Mariam Bouhmadi-López","doi":"10.1016/j.dark.2025.101845","DOIUrl":"10.1016/j.dark.2025.101845","url":null,"abstract":"<div><div>We analyse the cosmological evolution of a generalised axion-like field that drives the late-time acceleration of the Universe. This model can exhibit tracking behaviour, which alleviates the coincidence problem. The cosmological perturbations are carried within a multi-fluid approach where the scalar field is described by a non-adiabatic fluid, i.e., one whose speed of sound in the rest frame differs from the adiabatic one. The cosmological perturbations are solved since the radiation-dominated epoch, imposing initial adiabatic conditions for matter, radiation and the dark energy component, for modes well outside the Hubble horizon in the past. We analyse the homogeneous curvature perturbation, gravitational potential and dark energy perturbations in this model, as well as the matter power spectrum and f<span><math><msub><mrow><mi>σ</mi></mrow><mrow><mn>8</mn></mrow></msub></math></span>. We discuss which parameters of the model are more favoured observationally.</div></div>","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"48 ","pages":"Article 101845"},"PeriodicalIF":5.0,"publicationDate":"2025-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143312481","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":"Resonant graviton–photon conversion with stochastic magnetic field in the expanding universe","authors":"Andrea Addazi ,&nbsp;Salvatore Capozziello ,&nbsp;Qingyu Gan","doi":"10.1016/j.dark.2025.101844","DOIUrl":"10.1016/j.dark.2025.101844","url":null,"abstract":"<div><div>We investigate graviton–photon oscillations sourced by cosmological magnetic fields from Gertsenshtein effect. We adopt a robust perturbative approach and we find that the conversion probability from graviton to photon can be resonantly enhanced in monochromatic, multi-chromatic and scale invariant spectrum models of stochastic magnetic field fluctuations. In addition, the expansion of the Universe acts as a decoherence factor, which demands a natural discretization scheme along the line of sight. Including also decoherence from cosmic acceleration, we find that conversion probabilities for stochastic magnetic fields are completely different than results predicted from existing magnetic domain-like models in a wide range of magnetic strengths and correlation lengths. Resonances can be tested by radio telescopes as a probe of high frequency gravitational wave sources and primordial magnetogenesis mechanisms.</div></div>","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"48 ","pages":"Article 101844"},"PeriodicalIF":5.0,"publicationDate":"2025-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143312480","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":"Interplay of anisotropy and electric charge in modified matter-geometry coupled gravity model in the context of stellar structures","authors":"Tayyab Naseer ,&nbsp;M. Sharif ,&nbsp;Fatima Chand","doi":"10.1016/j.dark.2025.101840","DOIUrl":"10.1016/j.dark.2025.101840","url":null,"abstract":"<div><div>This paper presents two unique, singularity-free interior models within the framework of <span><math><mrow><mi>f</mi><mrow><mo>(</mo><mi>R</mi><mo>,</mo><msub><mrow><mi>L</mi></mrow><mrow><mi>m</mi></mrow></msub><mo>,</mo><mi>T</mi><mo>)</mo></mrow><mo>=</mo><mi>R</mi><mo>+</mo><mn>2</mn><msub><mrow><mi>c</mi></mrow><mrow><mn>1</mn></mrow></msub><msub><mrow><mi>L</mi></mrow><mrow><mi>m</mi></mrow></msub><mo>+</mo><msub><mrow><mi>c</mi></mrow><mrow><mn>2</mn></mrow></msub><mi>T</mi></mrow></math></span> gravity model, representing charged sphere coupled with the anisotropic fluid. For this, the field equations are formulated for a considered model of this extended theory and we observe this system of highly non-linear equations to be under-determined. By assuming specific forms of anisotropy and radial metric potential, we derive a couple of exact solutions for these governing equations. The smooth matching of the obtained interior solutions with the Reissner-Nordström exterior metric at the boundary of the compact star enables us to determine the values of integration constants associated with the developed solutions. In this regard, we also use the condition of vanishing radial pressure at the spherical interface. Afterwards, we thoroughly analyze physical properties of the resulting models using the observed data of a particular pulsar, namely 4U 1820-30. Different values of minimally coupled modified model parameters are also chosen to show the effects of correction terms. The findings of this study reveal that, for the chosen charge and model parametric values, both our solutions are well-aligned with the criteria whose fulfillment is necessary to ensure the physical existence of stellar structures.</div></div>","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"48 ","pages":"Article 101840"},"PeriodicalIF":5.0,"publicationDate":"2025-02-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143312479","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}