Physics of the Dark Universe最新文献

{"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":"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":"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":"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}

{"title":"Dynamics of particles surrounding a stationary, spherically-symmetric black hole with Nonlinear Electrodynamics","authors":"Erdem Sucu,&nbsp;İzzet Sakallı","doi":"10.1016/j.dark.2024.101771","DOIUrl":"10.1016/j.dark.2024.101771","url":null,"abstract":"<div><div>We study the dynamics of both timelike and lightlike particles in the vicinity of a stationary, spherically symmetric black hole governed by nonlinear electrodynamics (NED). The spacetime is modeled using an exact solution to Einstein’s field equations modified by a NED Lagrangian, which incorporates the influence of the black hole charge and NED parameter <span><math><mi>ζ</mi></math></span>. We derive the geodesic equations for test particles and photons, investigating their orbital motion, deflection angles, and photon sphere radii under the influence of NED. We also examine the stability of circular orbits for both charged and neutral particles and compute effective potentials for varying angular momentum and NED parameters. Our results generalize well-known black hole solutions, such as the Reissner-Nordström black hole, to include NED corrections, providing a richer understanding of particle behavior in strong gravitational fields. These findings have potential applications in black hole astrophysics and may offer insights into the nature of dark matter, quark confinement, and axions.</div></div>","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"47 ","pages":"Article 101771"},"PeriodicalIF":5.0,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143099727","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":"Non-canonical 3-form dark energy","authors":"Vitor da Fonseca ,&nbsp;Bruno J. Barros ,&nbsp;Tiago Barreiro ,&nbsp;Nelson J. Nunes","doi":"10.1016/j.dark.2025.101827","DOIUrl":"10.1016/j.dark.2025.101827","url":null,"abstract":"<div><div>In this study, we meticulously construct a 3-form Lagrangian designed to mimic the dynamics of both dust matter in the past and dark energy driving the acceleration in the present era. A dynamical systems approach is used to investigate the underlying behavior of the cosmological background. By investigating the influence of the potential slope and initial conditions on the dynamical solutions, we identify distinct viable scenarios capable of replicating a De Sitter universe in the present epoch. An intriguing aspect of the model is the existence of solutions describing multiple inflationary phases in which the 3-form self-interacting potential decays rapidly.</div></div>","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"47 ","pages":"Article 101827"},"PeriodicalIF":5.0,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143100664","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}