Physics of the Dark Universe最新文献

{"title":"Dynamical Black Hole in the accelerating Universe approaching the future singularity — Possible origin of (super-)massive black holes","authors":"Shin’ichi Nojiri ,&nbsp;Sergei D. Odintsov","doi":"10.1016/j.dark.2025.102104","DOIUrl":"10.1016/j.dark.2025.102104","url":null,"abstract":"<div><div>We construct and investigate the dynamical black hole spacetime embedded in the expanding universe filled with cosmic fluid, such as dark energy. When the equation of state (EoS) parameter of the fluid is a constant, we find exact solutions of the Einstein equation where the Schwarzschild black hole is embedded in the expanding universe. This solution differs from the well-known McVittie metric, where the EoS parameter is not a constant but rather depends on the radial coordinate. It is shown that a dynamical black hole grows with the expansion of the universe. If primordial black holes are created before or during inflation, above dynamical black holes might be the origin of the supermassive black holes at the centre of galaxies, massive black holes suggested by the GW231123 event, and also the dark matter. The case where the cosmic fluid EoS is more general is also considered so that the universe enters the epoch of finite-time future singularity. Thermodynamics and the behaviour of black holes around different future singularities are carefully investigated. It is then demonstrated that the black hole horizon enhances the tidal force, but near the horizon, the tidal force works to press the extended object, which is in contrast with a massive body near to future singularity. We also propose a new type of future singularity where the singularity inside the black hole is a sphere with a finite radius. When the radius of the spherical singularity becomes larger than the radius of the black hole horizon, it becomes naked. The universe may end up with a cosmic doomsday when the radius of the singularity becomes infinite.</div></div>","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"50 ","pages":"Article 102104"},"PeriodicalIF":6.4,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145220741","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 the Gaussian assumption in the estimation of parameters for dark energy models","authors":"Fabiola Arevalo ,&nbsp;Luis Firinguetti ,&nbsp;Marcos Peña","doi":"10.1016/j.dark.2025.102155","DOIUrl":"10.1016/j.dark.2025.102155","url":null,"abstract":"<div><div>The assumption of Gaussian distribution in Type Ia supernova data underlies most cosmological parameter estimates and led to the discovery of late acceleration. In this work, we assess the validity of this assumption using the Pantheon+ dataset and analyze its impact on parameter estimation for dark energy cosmological models.</div><div>We perform a comprehensive statistical, analysis including the Lilliefors and Jarque–Bera tests, to assess the normality of both the data and model residuals. We find that the Gaussianity assumption is untenable and that the redshift distribution is more accurately described by a t-distribution, as indicated by the Kolmogorov Smirnov test.</div><div>These statistical findings are explored within the framework of a nonlinear cosmological interaction for the dark sector. Free parameters are estimated using multiple methods, and bootstrap confidence intervals are constructed for them. Our results suggest that standard Gaussian assumptions may underestimate uncertainties in cosmological inference, and we advocate for incorporating more flexible statistical models in future analyses.</div></div>","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"50 ","pages":"Article 102155"},"PeriodicalIF":6.4,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145465753","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":"Reconstructing cosmic expansion in f(R,G) gravity using a log-periodic deceleration model","authors":"Amit Samaddar,&nbsp;S. Surendra Singh","doi":"10.1016/j.dark.2025.102081","DOIUrl":"10.1016/j.dark.2025.102081","url":null,"abstract":"&lt;div&gt;&lt;div&gt;We study the late-time cosmology in &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;R&lt;/mi&gt;&lt;mo&gt;,&lt;/mo&gt;&lt;mi&gt;G&lt;/mi&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/mrow&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mi&gt;R&lt;/mi&gt;&lt;mo&gt;+&lt;/mo&gt;&lt;mi&gt;α&lt;/mi&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mi&gt;R&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;mo&gt;+&lt;/mo&gt;&lt;mi&gt;β&lt;/mi&gt;&lt;msup&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;mi&gt;G&lt;/mi&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;, using a logarithmic parametrization of the deceleration parameter &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;q&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;q&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mo&gt;+&lt;/mo&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;q&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mi&gt;s&lt;/mi&gt;&lt;mi&gt;i&lt;/mi&gt;&lt;mi&gt;n&lt;/mi&gt;&lt;mrow&gt;&lt;mo&gt;[&lt;/mo&gt;&lt;mi&gt;l&lt;/mi&gt;&lt;mi&gt;o&lt;/mi&gt;&lt;mi&gt;g&lt;/mi&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;mo&gt;]&lt;/mo&gt;&lt;/mrow&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;. 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;/mrow&gt;&lt;/math&gt;&lt;/span&gt; is reconstructed and model parameters are constrained via MCMC analysis using CC (31), BAO 15+DESI DR2 BAO and Pantheon+SHOES (1701) datasets. Our results yield a Hubble constant in the range &lt;span&gt;&lt;math&gt;&lt;mrow&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;mo&gt;=&lt;/mo&gt;&lt;mn&gt;71&lt;/mn&gt;&lt;mo&gt;.&lt;/mo&gt;&lt;mn&gt;7&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;–72.8 km/s/Mpc, consistent with late-time observations. The present deceleration parameter is found to be &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;q&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;mo&gt;.&lt;/mo&gt;&lt;mn&gt;484&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; to &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;mo&gt;.&lt;/mo&gt;&lt;mn&gt;517&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;, while the evolution parameter &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;q&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mo&gt;≈&lt;/mo&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;, indicating increasing acceleration. The transition redshift shifts from &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;z&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;t&lt;/mi&gt;&lt;mi&gt;r&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;mo&gt;.&lt;/mo&gt;&lt;mn&gt;879&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; (CC) to 0.744 (CC+BAO+Pantheon+SHOES), supporting a dynamic acceleration phase. The model reproduces early radiation behavior with &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;ω&lt;/mi&gt;&lt;mrow&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mi&gt;z&lt;/mi&gt;&lt;mo&gt;&gt;&lt;/mo&gt;&lt;mo&gt;&gt;&lt;/mo&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/mrow&gt;&lt;mo&gt;≈&lt;/mo&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;mo&gt;.&lt;/mo&gt;&lt;mn&gt;33&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; and predicts present-day values &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;ω&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mo&gt;≈&lt;/mo&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;mo&gt;.&lt;/mo&gt;&lt;mn&gt;49&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;. Energy conditions NEC and DEC are satisfied, while SEC is violated at late times. The statefinder parameters &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mrow&gt;&lt;mo&gt;{&lt;/mo&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;r&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mo&gt;,&lt;/mo&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;s&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mo&gt;}&lt;/mo&gt;&lt;/mrow&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mrow&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;mo&gt;.&lt;/mo&gt;&lt;mn&gt;866&lt;/mn&gt;&lt;mo&gt;,&lt;/mo&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;mo&gt;.&lt;/mo&gt;&lt;mn&gt;046&lt;/mn&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/mrow&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; lie near the &lt;span&gt;&lt;math&gt;&lt;mi&gt;Λ&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt;CDM point. Estimated age of the Universe ranges from 13.01 to 13.59 Gyr. Ther","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"50 ","pages":"Article 102081"},"PeriodicalIF":6.4,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145105927","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":"Kalb-Ramond black holes sourced by ModMax electrodynamics: Some perturbative properties in the phantom sector","authors":"Y. Sekhmani ,&nbsp;A. Baruah ,&nbsp;S.K. Maurya ,&nbsp;J. Rayimbaev ,&nbsp;M. Altanji ,&nbsp;I. Ibragimov ,&nbsp;S. Muminov","doi":"10.1016/j.dark.2025.102157","DOIUrl":"10.1016/j.dark.2025.102157","url":null,"abstract":"<div><div>We formulate and analyse a new class of electrically charged black hole (BH) solutions in Lorentz-violating gravity, where nonlinear ModMax electrodynamics is nonminimally coupled to a Kalb–Ramond (KR) two-form field. The spontaneous breaking of local Lorentz symmetry is triggered by a nonzero vacuum expectation value of the KR field, characterized by a small dimensionless parameter <span><math><mi>ℓ</mi></math></span>. To incorporate both the standard and phantom sectors, we introduce a discrete sign-flip parameter <span><math><mrow><mi>ζ</mi><mo>=</mo><mo>±</mo><mn>1</mn></mrow></math></span> that flips the gauge-kinetic terms in the phantom (<span><math><mrow><mi>ζ</mi><mo>=</mo><mo>−</mo><mn>1</mn></mrow></math></span>) branch. Assuming a vanishing cosmological constant and self-interacting potential with minimum <span><math><mrow><msup><mrow><mi>V</mi></mrow><mrow><mo>′</mo></mrow></msup><mo>=</mo><mn>0</mn></mrow></math></span>, we obtain exact analytical solutions for the metric function and electric potential. The resulting spacetime interpolates between Schwarzschild, Reissner–Nordström, and ModMax BHs, with curvature scalars showing deviations controlled by <span><math><mrow><mo>(</mo><mi>ℓ</mi><mo>,</mo><mi>γ</mi><mo>,</mo><mi>ζ</mi><mo>)</mo></mrow></math></span>. We study scalar, electromagnetic, and gravitational perturbations using both frequency-domain (Padé-averaged WKB) and time-domain (Gundlach–Price–Pullin ＋ Prony) methods. We find that increasing either <span><math><mi>ℓ</mi></math></span> or the ModMax parameter <span><math><mi>γ</mi></math></span> enhances the real and imaginary parts of quasinormal modes, indicating higher oscillation frequencies and faster damping, especially in the phantom sector. The effective potentials deepen under phantom deformation, supporting more tightly bound modes. Furthermore, we analyse the greybody factors and compute the sparsity <span><math><mi>η</mi></math></span> of Hawking radiation, which quantifies the non-thermal character of particle emission. We show that <span><math><mi>η</mi></math></span> is significantly affected by <span><math><mi>ℓ</mi></math></span>, decreasing with increasing Lorentz violation and asymptotically approaching a scaled version of the Schwarzschild value.</div></div>","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"50 ","pages":"Article 102157"},"PeriodicalIF":6.4,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145465215","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 the Frolov black hole via weak gravitational plasma lensing","authors":"Farzan Mushtaq ,&nbsp;Xia Tiecheng ,&nbsp;Allah Ditta ,&nbsp;Waheed Al-Masry ,&nbsp;Ateyah A. Al-Zahrani ,&nbsp;Shahid M. Ramay ,&nbsp;Asif Mahmood","doi":"10.1016/j.dark.2025.102094","DOIUrl":"10.1016/j.dark.2025.102094","url":null,"abstract":"<div><div>This study investigates the properties of the weak gravitational lensing by using the Gauss–Bonnet theorem in the context of the Frolov black hole. By employing the Gauss–Bonnet theorem, we determine the deflection angle of the black hole for spherically balanced space–time and derive the Gaussian optical curvature. The resulting light deflection angle at the weak field limits demonstrates that light bending is a topological and universal process. Additionally, we determine the light’s deflection angle within the plasma medium’s framework. Furthermore, under the impact of plasma medium and for non-plasma medium, the behaviour of the deflection angle is demonstrated explicitly by the black hole. This research also investigates the related properties of particle dynamics including, effective force and the Lyapunov component. Hence, greater deflection angle depicts the greater photon frequency. Thus, increase in parameters <span><math><mrow><mi>η</mi><mo>,</mo><mspace></mspace><mi>q</mi><mo>,</mo><mspace></mspace><mi>a</mi></mrow></math></span> forecasts decrease in photon frequency and increase in <span><math><mi>α</mi></math></span> and plasma medium <span><math><mi>N</mi></math></span> suggests increase photon frequency. Lyapunov exponent indicates suggests the stability of the black hole solution. In terms of effective force parameters <span><math><mi>η</mi></math></span>, <span><math><mi>q</mi></math></span> and <span><math><mi>a</mi></math></span> suggests weak attraction of the particle whereas parameters <span><math><mi>α</mi></math></span> suggests strong attractions.</div></div>","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"50 ","pages":"Article 102094"},"PeriodicalIF":6.4,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145118428","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":"Entropy analysis of dark matter halo structures","authors":"Abdelhakim Benkrane","doi":"10.1016/j.dark.2025.102130","DOIUrl":"10.1016/j.dark.2025.102130","url":null,"abstract":"<div><div>In this work, we derive the entropy of dark matter halos described by double (broken) power-law density profiles, motivated by Verlinde’s view of gravity as an emergent entropic phenomenon. We consider four halo models – the Dehnen-type, Hernquist, Jaffe, and Plummer spheres – along with the perfect sphere, deriving their entropy expressions and testing consistency with the second law of thermodynamics. All models, except the perfect sphere, satisfy the second law. We further extend the analysis to a cosmological framework, examining how these entropy forms affect the Friedmann equations. By plotting the energy density against the central halo radius <span><math><msub><mrow><mi>r</mi></mrow><mrow><mn>0</mn></mrow></msub></math></span>, we find that increasing <span><math><msub><mrow><mi>r</mi></mrow><mrow><mn>0</mn></mrow></msub></math></span> decreases the energy density.</div></div>","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"50 ","pages":"Article 102130"},"PeriodicalIF":6.4,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145320465","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 gravitational decoupling on relativistic compact models admitting a linear equation of state","authors":"Tayyab Naseer ,&nbsp;M. Sharif ,&nbsp;Aleena Tehreem","doi":"10.1016/j.dark.2025.102133","DOIUrl":"10.1016/j.dark.2025.102133","url":null,"abstract":"<div><div>In the context of the Einstein gravity theory, this investigation uses minimal geometric deformation to develop two exact extensions of the existing anisotropic solutions. In order to do this, we consider a static spherical interior that is initially filled with the anisotropic fluid, referred to a seed source. A Lagrangian corresponding to a new source is then introduced, taking into consideration that the parent fluid distribution is gravitationally linked with the new source. Two distinct systems of equations are produced after applying a transformation to the radial component following the computation of the field equations for the entire matter setup. Using different constraints, these sets are solved separately, producing novel solutions. Furthermore, matching criteria between the exterior and interior geometries are used to determine the constants appeared in the interior solutions. Afterwards, the graphical examination of the proposed models is carried out using the estimated mass and radius of a star candidate <span><math><mrow><mi>V</mi><mi>e</mi><mi>l</mi><mi>a</mi><mspace></mspace><mi>X</mi><mo>−</mo><mn>1</mn></mrow></math></span>. Finally, we conclude that, for the considered choices of the decoupling parameter, our resulting relativistic models agree well with the acceptance criteria.</div></div>","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"50 ","pages":"Article 102133"},"PeriodicalIF":6.4,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145320527","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 comprehensive dynamical and phenomenological analysis of structure growth in curvature-modulated coupled quintessence scenario","authors":"Anirban Chatterjee,&nbsp;Yungui Gong","doi":"10.1016/j.dark.2025.102137","DOIUrl":"10.1016/j.dark.2025.102137","url":null,"abstract":"<div><div>We investigate an interacting dark energy–dark matter model within the quintessence framework, characterized by the coupling term <span><math><mrow><msub><mrow><mi>Q</mi></mrow><mrow><mn>0</mn></mrow></msub><mo>=</mo><mi>α</mi><mi>κ</mi><msub><mrow><mi>ρ</mi></mrow><mrow><mi>m</mi></mrow></msub><mover><mrow><mi>ϕ</mi></mrow><mrow><mo>̇</mo></mrow></mover><mfenced><mrow><mn>1</mn><mo>−</mo><mi>β</mi><mi>R</mi><mo>/</mo><mrow><mo>(</mo><mn>6</mn><msup><mrow><mi>H</mi></mrow><mrow><mn>2</mn></mrow></msup><mo>)</mo></mrow></mrow></mfenced></mrow></math></span>, and the scalar field evolves under an exponential potential <span><math><mrow><mi>V</mi><mrow><mo>(</mo><mi>ϕ</mi><mo>)</mo></mrow><mo>=</mo><msub><mrow><mi>V</mi></mrow><mrow><mn>0</mn></mrow></msub><msup><mrow><mi>e</mi></mrow><mrow><mo>−</mo><mi>λ</mi><mi>κ</mi><mi>ϕ</mi></mrow></msup></mrow></math></span>, with parameters <span><math><mi>α</mi></math></span>, <span><math><mi>λ</mi></math></span>, and <span><math><mi>β</mi></math></span>. Recasting the cosmological equations into a first-order autonomous system using dimensionless variables, we perform a phase space analysis to identify conditions for stable, non-phantom accelerating attractors. The Ricci scalar term, controlled by <span><math><mi>β</mi></math></span>, significantly affects the stability of critical points, with attractors transitioning to repellers for higher values of <span><math><mi>β</mi></math></span>. We also analyze linear scalar perturbations, focusing on the matter density contrast <span><math><msub><mrow><mi>δ</mi></mrow><mrow><mi>m</mi></mrow></msub></math></span> and the growth index <span><math><mi>γ</mi></math></span>. Additionally, we compute the deceleration and jerk parameters, the Hubble rate, and the distance modulus <span><math><mrow><mi>μ</mi><mrow><mo>(</mo><mi>z</mi><mo>)</mo></mrow></mrow></math></span>, showing good agreement with observational data. The model naturally addresses the cosmic coincidence problem through scalar field tracking behavior. For moderate parameter values, matter perturbations continue to grow into the future, capturing both background and perturbative dynamics effectively. This framework thus offers a consistent and observationally viable approach to interacting dark energy.</div></div>","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"50 ","pages":"Article 102137"},"PeriodicalIF":6.4,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145415949","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":"Frolov–AdS black holes immersed in a string fluid: Harmonic oscillations, phase structure, and topological classification","authors":"Saeed Noori Gashti ,&nbsp;Yassine Sekhmani ,&nbsp;Mohammad Ali S. Afshar ,&nbsp;Mohammad Reza Alipour ,&nbsp;Abdul Jawad ,&nbsp;İzzet Sakallı ,&nbsp;B. Pourhassan ,&nbsp;Sanjar Shaymatov ,&nbsp;J. Sadeghi ,&nbsp;J. Rayimbaev","doi":"10.1016/j.dark.2025.102150","DOIUrl":"10.1016/j.dark.2025.102150","url":null,"abstract":"<div><div>This work examines the thermodynamic topology of Frolov–AdS black holes with a surrounding string fluid, highlighting the role of topological charges in determining stability. By analyzing vector fields constructed from the free energy, we identify zero points corresponding to distinct topological charges, which vary with entropy-related parameters. Our findings demonstrate that the system exhibits topological charges of <span><math><mo>+</mo></math></span>1, 0, or <span><math><mo>−</mo></math></span>1, serving as a robust criterion for black hole stability classification. Furthermore, we examine photon sphere (PS) configurations, revealing that their associated (PS = <span><math><mo>−</mo></math></span>1) reflect underlying geometric and thermodynamic structures of black hole. This study establishes connections between winding numbers and black hole phase transitions. Comparative analyses with classical black holes support the universality of the topological framework. Complementarily, the analysis of quasi-periodic oscillations elucidates the intricate interplay of electric charge, spin, cosmological constant, and string-fluid background on epicyclic and precessional motions around charged AdS black holes. Electric charge diminishes gravitational binding, shifting characteristic frequencies outward, while spin-induced frame dragging enhances orbital stability and periapsis advance. The AdS curvature associated with a negative cosmological constant universally suppresses oscillatory frequencies and modifies periastron dynamics, whereas the string-fluid parameter governs asymptotic decay rates and far-field behavior. These combined effects yield comprehensive predictions for quasinormal mode spectra and potential astrophysical signatures.</div></div>","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"50 ","pages":"Article 102150"},"PeriodicalIF":6.4,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145415952","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":"III. Interacting Dark Energy: Summary of models, Pathologies, and Constraints","authors":"Marcel van der Westhuizen ,&nbsp;Amare Abebe ,&nbsp;Eleonora Di Valentino","doi":"10.1016/j.dark.2025.102121","DOIUrl":"10.1016/j.dark.2025.102121","url":null,"abstract":"&lt;div&gt;&lt;div&gt;We present an overview of the main results from our two companion papers that are relevant for observational constraints on interacting dark energy (IDE) models. We provide analytical solutions for the dark matter and dark energy densities, &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;ρ&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;dm&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt; and &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;ρ&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;de&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt;, as well as the normalized Hubble function &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;/mrow&gt;&lt;/math&gt;&lt;/span&gt;, for eight IDE models. These include five linear IDE models, namely &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;Q&lt;/mi&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;3&lt;/mn&gt;&lt;mi&gt;H&lt;/mi&gt;&lt;mrow&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;δ&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;dm&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;ρ&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;dm&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mo&gt;+&lt;/mo&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;δ&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;de&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;ρ&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;de&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/mrow&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; and four special cases: &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;Q&lt;/mi&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;3&lt;/mn&gt;&lt;mi&gt;H&lt;/mi&gt;&lt;mi&gt;δ&lt;/mi&gt;&lt;mrow&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;ρ&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;dm&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mo&gt;+&lt;/mo&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;ρ&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;de&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&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;Q&lt;/mi&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;3&lt;/mn&gt;&lt;mi&gt;H&lt;/mi&gt;&lt;mi&gt;δ&lt;/mi&gt;&lt;mrow&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;ρ&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;dm&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;ρ&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;de&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&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;Q&lt;/mi&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;3&lt;/mn&gt;&lt;mi&gt;H&lt;/mi&gt;&lt;mi&gt;δ&lt;/mi&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;ρ&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;dm&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;, and &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;Q&lt;/mi&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;3&lt;/mn&gt;&lt;mi&gt;H&lt;/mi&gt;&lt;mi&gt;δ&lt;/mi&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;ρ&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;de&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;, together with three non-linear IDE models: &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;Q&lt;/mi&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;3&lt;/mn&gt;&lt;mi&gt;H&lt;/mi&gt;&lt;mi&gt;δ&lt;/mi&gt;&lt;mfenced&gt;&lt;mrow&gt;&lt;mfrac&gt;&lt;mrow&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;ρ&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;dm&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;ρ&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;de&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;ρ&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;dm&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mo&gt;+&lt;/mo&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;ρ&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;de&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/mrow&gt;&lt;/mfrac&gt;&lt;/mrow&gt;&lt;/mfenced&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;, &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;Q&lt;/mi&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;3&lt;/mn&gt;&lt;mi&gt;H&lt;/mi&gt;&lt;mi&gt;δ&lt;/mi&gt;&lt;mfenced&gt;&lt;mrow&gt;&lt;mfrac&gt;&lt;mrow&gt;&lt;msubsup&gt;&lt;mrow&gt;&lt;mi&gt;ρ&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;dm&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/mrow&gt;&lt;/msubsup&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;ρ&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;dm&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mo&gt;+&lt;/mo&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;ρ&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;de&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/mrow&gt;&lt;/mfrac&gt;&lt;/mrow&gt;&lt;/mfenced&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;, and &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;Q&lt;/mi&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;3&lt;/mn&gt;&lt;mi&gt;H&lt;/mi&gt;&lt;mi&gt;δ&lt;/mi&gt;&lt;mfenced&gt;&lt;mrow&gt;&lt;mfrac&gt;&lt;mrow&gt;&lt;msubsup&gt;&lt;mrow&gt;&lt;mi&gt;ρ&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;de&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/mrow&gt;&lt;/msubsup&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;ρ&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;dm&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mo&gt;+&lt;/mo&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;ρ&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;de&lt;/mi&gt;&lt;/mrow&gt;&lt;","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"50 ","pages":"Article 102121"},"PeriodicalIF":6.4,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145320461","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}