Physics of the Dark Universe最新文献

{"title":"Wormhole solutions in dRGT gravity via Ultra-Diffuse Galaxies and Navarro–Frenk–White Dark halos using galactic rotation curve","authors":"Sourav Chaudhary ,&nbsp;S.K. Maurya ,&nbsp;Jitendra Kumar","doi":"10.1016/j.dark.2025.102019","DOIUrl":"10.1016/j.dark.2025.102019","url":null,"abstract":"<div><div>This work explores wormhole formation in galactic halos using dRGT gravity, considering two dark matter profiles: Ultra-Diffuse Galaxies (UDG) and the Navarro–Frenk–White (NFW) model. Inspired by Rahaman et al. [ <span><span>Can. J. Phys. 97, no.3, 241-247 (2019)</span><svg><path></path></svg></span>], this work presents a detailed graphical investigation of the nature of exotic matter in the wormhole framework, alongside a condition-based energy assessment of the content of the matter. The derived shape functions of the wormhole geometry meet the necessary criteria in both cases. Our study presents a novel wormhole solution supported by dark matter, with the redshift and shape functions constructed from the UDG and NFW density profiles along with the corresponding rotational velocity. We observe that in Model I, NEC is violated in the region surrounding the wormhole throat, whereas in Model II, the violation is present throughout the entire wormhole configuration. In addition, we analyze the forces that maintain equilibrium in the system and use embedding diagrams to visualize the geometry of the wormhole. This study also investigates the properties of dimensionless anisotropy and exoticity. Our results suggest that dark matter may help sustain these structures, offering new perspectives on its influence in galactic dynamics.</div></div>","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"49 ","pages":"Article 102019"},"PeriodicalIF":5.0,"publicationDate":"2025-07-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144694797","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 gravastar models in f(R, T) gravity with Heintzmann geometry","authors":"Arfa Waseem ,&nbsp;A. Eid ,&nbsp;Salma Yaqoob ,&nbsp;Faisal Javed","doi":"10.1016/j.dark.2025.102006","DOIUrl":"10.1016/j.dark.2025.102006","url":null,"abstract":"<div><div>Gravastars have gained significant attention as a viable alternative to black holes, providing a resolution to the singularity problem while maintaining a strong theoretical foundation. In this work, we construct a gravastar model within the f(R, <span><math><mi>T</mi></math></span>) framework, employing the Mazur Mottola formalism and utilizing the temporal component of the Heintzmann spacetime to characterize the interior structure. The model comprises three distinct regions: a core with negative energy density, an intermediate thin shell of ultra-relativistic stiff fluid, and an exterior assumed to be de Sitter spacetime which can be governed by the Schwarzschild solution. Under this specification, we derive a set of exact and singularity-free solutions of the gravastar and a comprehensive analysis of the shell’s fundamental attributes, including its geometric thickness, energy content, entropy, surface pressure, density, and equation of state parameter, is conducted. Through rigorous graphical evaluation, we establish the dynamical stability of the proposed configuration, reinforcing the viability of gravastars as astrophysical entities within the broader framework of modified gravity.</div></div>","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"49 ","pages":"Article 102006"},"PeriodicalIF":5.0,"publicationDate":"2025-07-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144714102","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":"Effective equation of state oscillations at matter–radiation equality and primordial gravitational waves","authors":"S.D. Odintsov ,&nbsp;V.K. Oikonomou","doi":"10.1016/j.dark.2025.102016","DOIUrl":"10.1016/j.dark.2025.102016","url":null,"abstract":"<div><div>The theory controlling the Universe’s evolution in the classical regime has to be motivated by particle physics reasoning and should also generate inflation and dark energy eras in a unified way. One such framework is <span><math><mrow><mi>F</mi><mrow><mo>(</mo><mi>R</mi><mo>)</mo></mrow></mrow></math></span> gravity. In this work we examine a class of exponential deformations of <span><math><msup><mrow><mi>R</mi></mrow><mrow><mn>2</mn></mrow></msup></math></span> gravity motivated by fundamental physics of scalaron evolution in a de Sitter background. As we show this class of models describe both inflation and the dark energy era in a viable way compatible with the Planck constraints on inflation and the cosmological parameters. Regarding the inflationary era, the exponentially deformed <span><math><msup><mrow><mi>R</mi></mrow><mrow><mn>2</mn></mrow></msup></math></span> model also yields a rescaled Einstein–Hilbert term which remarkably does not affect the dynamics and the inflationary evolution is identical to that of an <span><math><msup><mrow><mi>R</mi></mrow><mrow><mn>2</mn></mrow></msup></math></span> model. The dark energy era is also found to be viable and mimics the <span><math><mi>Λ</mi></math></span>-Cold-Dark-Matter model. More importantly, this class of <span><math><mrow><mi>F</mi><mrow><mo>(</mo><mi>R</mi><mo>)</mo></mrow></mrow></math></span> gravity exponential <span><math><msup><mrow><mi>R</mi></mrow><mrow><mn>2</mn></mrow></msup></math></span> deformations also has an important characteristic, and specifically it yields total equation of state oscillations deeply in the matter domination era, for redshifts <span><math><mrow><mi>z</mi><mo>∼</mo><mn>3400</mn></mrow></math></span>, so near the matter–radiation equality. These total equation of state deformations at such a large redshift may directly affect the energy spectrum of the primordial gravitational waves. Indeed as we show, the effect is measurable and it leads to an enhancement of the tensor perturbations energy spectrum for low frequencies probed by the future LiteBIRD mission. This enhancement might have a measurable effect on the <span><math><mi>B</mi></math></span>-modes of the Cosmic Microwave Background radiation and thus may be detectable by the LiteBIRD mission. Only a handful of theoretical frameworks can generate the gravitational wave pattern generated by the class of exponentially deformed <span><math><msup><mrow><mi>R</mi></mrow><mrow><mn>2</mn></mrow></msup></math></span> models we presented.</div></div>","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"49 ","pages":"Article 102016"},"PeriodicalIF":5.0,"publicationDate":"2025-07-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144694799","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":"Limiting the Yukawa gravity through the black hole shadows of Sgr A* and M87*","authors":"Yuan Tan,&nbsp;Youjun Lu,&nbsp;Kunyu Song","doi":"10.1016/j.dark.2025.102017","DOIUrl":"10.1016/j.dark.2025.102017","url":null,"abstract":"&lt;div&gt;&lt;div&gt;Recently, the &lt;em&gt;EHT&lt;/em&gt; collaboration unveiled the shadow images of the supermassive black hole (SMBH) M87* and Sgr A*, with angular radii of &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mn&gt;42&lt;/mn&gt;&lt;mo&gt;±&lt;/mo&gt;&lt;mn&gt;3&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; &lt;!--&gt; &lt;span&gt;&lt;math&gt;&lt;mi&gt;μ&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt;as and &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mn&gt;48&lt;/mn&gt;&lt;mo&gt;.&lt;/mo&gt;&lt;mn&gt;7&lt;/mn&gt;&lt;mo&gt;±&lt;/mo&gt;&lt;mn&gt;7&lt;/mn&gt;&lt;mo&gt;.&lt;/mo&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; &lt;!--&gt; &lt;span&gt;&lt;math&gt;&lt;mi&gt;μ&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt;as, respectively. These observations are consistent with the shadow of a Kerr black hole in general relativity (GR). Observations of the shadow of SMBHs can be used to test modified gravity theories, including Yukawa gravity, in extremely strong fields. In this paper, we illustrate the shadows of Yukawa black holes, showing that their sizes are significantly influenced by the Yukawa parameters &lt;span&gt;&lt;math&gt;&lt;mi&gt;λ&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt; and &lt;span&gt;&lt;math&gt;&lt;mi&gt;κ&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt;. Using the EHT observations of M87* and Sgr A*, we obtain constraints on the Yukawa parameters. For Sgr A*, Keck and VLTI provide different priors on its gravitational radius. The Sgr A* shadow yields &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;κ&lt;/mi&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;0&lt;/mn&gt;&lt;msubsup&gt;&lt;mrow&gt;&lt;mn&gt;4&lt;/mn&gt;&lt;/mrow&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;10&lt;/mn&gt;&lt;/mrow&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;09&lt;/mn&gt;&lt;/mrow&gt;&lt;/msubsup&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; for &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;λ&lt;/mi&gt;&lt;mo&gt;&gt;&lt;/mo&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; &lt;!--&gt; &lt;!--&gt;AU with the Keck prior, while &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;κ&lt;/mi&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;0&lt;/mn&gt;&lt;msubsup&gt;&lt;mrow&gt;&lt;mn&gt;8&lt;/mn&gt;&lt;/mrow&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;06&lt;/mn&gt;&lt;/mrow&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;09&lt;/mn&gt;&lt;/mrow&gt;&lt;/msubsup&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; with the VLTI prior. As &lt;span&gt;&lt;math&gt;&lt;mi&gt;λ&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt; decreases, the constraints weaken, reaching &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;37&lt;/mn&gt;&lt;mo&gt;&lt;&lt;/mo&gt;&lt;mi&gt;κ&lt;/mi&gt;&lt;mo&gt;&lt;&lt;/mo&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;mo&gt;.&lt;/mo&gt;&lt;mn&gt;17&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; (Keck prior) and &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;47&lt;/mn&gt;&lt;mo&gt;&lt;&lt;/mo&gt;&lt;mi&gt;κ&lt;/mi&gt;&lt;mo&gt;&lt;&lt;/mo&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;mo&gt;.&lt;/mo&gt;&lt;mn&gt;04&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; (VLTI prior) at &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;λ&lt;/mi&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;mo&gt;.&lt;/mo&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; &lt;!--&gt; &lt;!--&gt;AU. For M87*, with a mass significantly larger than Sgr A*, this system can only put constraints on &lt;span&gt;&lt;math&gt;&lt;mi&gt;κ&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt; at larger &lt;span&gt;&lt;math&gt;&lt;mi&gt;λ&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt;. For &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;λ&lt;/mi&gt;&lt;mo&gt;&gt;&lt;/mo&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;mo&gt;.&lt;/mo&gt;&lt;mn&gt;5&lt;/mn&gt;&lt;mo&gt;×&lt;/mo&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;4&lt;/mn&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; &lt;!--&gt; &lt;!--&gt;AU, the &lt;em&gt;EHT&lt;/em&gt; observation of M87* yields &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;κ&lt;/mi&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;0&lt;/mn&gt;&lt;msubsup&gt;&lt;mrow&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;/mrow&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;17&lt;/mn&gt;&lt;/mrow&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;17&lt;/mn&gt;&lt;/mrow&gt;&lt;/msubsup&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;. No significant deviation from GR is detected in our analysis. Additional","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"49 ","pages":"Article 102017"},"PeriodicalIF":6.4,"publicationDate":"2025-07-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144721968","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 black hole evolution through homogeneous gravitational collapse in f(Q) gravity","authors":"Shubham Sharma ,&nbsp;Rajesh Kumar ,&nbsp;Shibesh Kumar Jas Pacif","doi":"10.1016/j.dark.2025.102020","DOIUrl":"10.1016/j.dark.2025.102020","url":null,"abstract":"<div><div>In this study, we investigate black hole (BH) formation resulting from the gravitational collapse of self-gravitating systems within the context of <span><math><mrow><mi>f</mi><mrow><mo>(</mo><mi>Q</mi><mo>)</mo></mrow></mrow></math></span> gravity. This work addresses key unresolved issues in theoretical physics regarding the end stage of gravitational collapse in massive stars. Building on the foundational research of Oppenheimer and Snyder (1939), we analyze a homogeneous collapsing system with perfect fluid distributions under <span><math><mrow><mi>f</mi><mrow><mo>(</mo><mi>Q</mi><mo>)</mo></mrow><mo>=</mo><mi>Q</mi><mo>+</mo><mi>α</mi><msup><mrow><mi>Q</mi></mrow><mrow><mn>2</mn></mrow></msup></mrow></math></span> gravity theory. To achieve this, we consider a homogeneous collapsing system with a spherically symmetric space–time geometry described by the FLRW metric with prefect fluid matter distribution. We have also discussed the junction conditions <span><math><mrow><mi>f</mi><mrow><mo>(</mo><mi>Q</mi><mo>)</mo></mrow></mrow></math></span> theory. By employing a parametrization of the expansion scalar, we derive an exact, model-independent solution to the Einstein field equations for the collapsing system. To explore the physical viability of the model we consider some known massive stars- <span><math><mrow><mi>R</mi><mn>136</mn><mi>a</mi><mn>3</mn><mo>,</mo><mi>R</mi><mn>136</mn><mi>c</mi></mrow></math></span>, and <span><math><mrow><mi>R</mi><mn>99</mn></mrow></math></span> with their known astrophysical stellar data (masses and radii). We discuss the formation of apparent horizon and space–time singularity, which further predicts BH as the final state of these collapsing stars. Additionally, we calculate the lifespans of these stellar objects, showing that higher-mass stars have shorter lifespans compared to less massive stars. We have also applied various test, including energy conditions, the equation of state, and stability criteria, and the adiabatic index. We have also presented a comparative analysis of our solution with standard Einstein’s General Relativity.</div></div>","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"49 ","pages":"Article 102020"},"PeriodicalIF":5.0,"publicationDate":"2025-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144672113","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":"Analytical polyΛCDM dynamics","authors":"Pierros Ntelis ,&nbsp;Jackson Levi Said","doi":"10.1016/j.dark.2025.101985","DOIUrl":"10.1016/j.dark.2025.101985","url":null,"abstract":"&lt;div&gt;&lt;div&gt;In this paper, we study the &lt;span&gt;&lt;math&gt;&lt;mi&gt;ϕ&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt;CDM and the &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;p&lt;/mi&gt;&lt;mi&gt;o&lt;/mi&gt;&lt;mi&gt;l&lt;/mi&gt;&lt;mi&gt;y&lt;/mi&gt;&lt;mi&gt;Λ&lt;/mi&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;CDM models and compare them to the standard concordance model, the vanilla &lt;span&gt;&lt;math&gt;&lt;mi&gt;Λ&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt;CDM.&lt;/div&gt;&lt;div&gt;Analytical solutions for the &lt;span&gt;&lt;math&gt;&lt;mi&gt;ϕ&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt;CDM model, vital for precision, show sub-% agreement with &lt;span&gt;&lt;math&gt;&lt;mi&gt;Λ&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt;CDM due to selected energy density components, yet larger differences from numerical solutions of the same equations underscore their reliability over numerical integration of stiff systems.&lt;/div&gt;&lt;div&gt;The &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;p&lt;/mi&gt;&lt;mi&gt;o&lt;/mi&gt;&lt;mi&gt;l&lt;/mi&gt;&lt;mi&gt;y&lt;/mi&gt;&lt;mi&gt;Λ&lt;/mi&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;CDM model is a phenomenological modified gravity model. We analyse their respective epoch evolutions, perform a detailed analytical and numerical dynamical analysis for each, and conduct a comparative study between the frameworks. Our work revitalizes these models by incorporating systems with an expanded set of variables, enabling us to derive analytical expressions for the energy density ratios of all species in both models. Moreover, the &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;p&lt;/mi&gt;&lt;mi&gt;o&lt;/mi&gt;&lt;mi&gt;l&lt;/mi&gt;&lt;mi&gt;y&lt;/mi&gt;&lt;mi&gt;Λ&lt;/mi&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;CDM model we present is both more comprehensive and streamlined compared to existing studies. It captures all known cosmic epochs, including radiation, matter, and dark energy phases, and more exotic ones. The &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;p&lt;/mi&gt;&lt;mi&gt;o&lt;/mi&gt;&lt;mi&gt;l&lt;/mi&gt;&lt;mi&gt;y&lt;/mi&gt;&lt;mi&gt;Λ&lt;/mi&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;CDM model has the cosmological constant term dominance in the far future epoch.&lt;/div&gt;&lt;div&gt;For the &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;p&lt;/mi&gt;&lt;mi&gt;o&lt;/mi&gt;&lt;mi&gt;l&lt;/mi&gt;&lt;mi&gt;y&lt;/mi&gt;&lt;mi&gt;Λ&lt;/mi&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;CDM model, we find &lt;em&gt;the global transition from a pure reflector of the dark energy dark matter exchange dominant component, to the saddle reflector points of matter, radiation, curvature, modified gravity components, and then we transit to the SVT modified gravity component attractor-saddle epoch, which also transits to the final cosmological constant, attractor epoch, in the far future. Note that there is saddle transition between the modified gravity dominant component and the SVT modified gravity component. Note that there is saddle transition between the SVT modified gravity and the cosmological constant component in the far future.&lt;/em&gt;&lt;/div&gt;&lt;div&gt;Our findings show that all three models effectively describe the widely accepted cosmic evolution scenario and align with current observations. While all &lt;span&gt;&lt;math&gt;&lt;mi&gt;Λ&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt;CDM, &lt;span&gt;&lt;math&gt;&lt;mi&gt;ϕ&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt;CDM, and &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;p&lt;/mi&gt;&lt;mi&gt;o&lt;/mi&gt;&lt;mi&gt;l&lt;/mi&gt;&lt;mi&gt;y&lt;/mi&gt;&lt;mi&gt;Λ&lt;/mi&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;CDM reproduce the qualitative and quantitative behaviour of the universe’s species across epochs, the &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;p&lt;/mi&gt;&lt;mi&gt;o&lt;/mi&gt;&lt;mi&gt;l&lt;/mi&gt;&lt;mi&gt;y&lt;/mi&gt;&lt;mi&gt;Λ&lt;/mi&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;CDM model exhibits a richer phenomenology, ","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"49 ","pages":"Article 101985"},"PeriodicalIF":5.0,"publicationDate":"2025-07-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144655801","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":"Fuzzy dark matter fails to explain dark matter cores","authors":"María Benito ,&nbsp;Gert Hütsi ,&nbsp;Kristjan Müürsepp ,&nbsp;Jorge Sánchez Almeida ,&nbsp;Juan Urrutia ,&nbsp;Ville Vaskonen ,&nbsp;Hardi Veermäe","doi":"10.1016/j.dark.2025.102010","DOIUrl":"10.1016/j.dark.2025.102010","url":null,"abstract":"<div><div>Ultrafaint dwarf galaxies (UFDs) are ideal for studying dark matter (DM) due to minimal baryonic effects. UFD observations suggest cored DM profiles. We find that the core radius–stellar mass scaling predicted by fuzzy dark matter (FDM) is at <span><math><mrow><mn>6</mn><mo>.</mo><mn>1</mn><mi>σ</mi></mrow></math></span> tension with UFD observations. Combining observations from 27 UFDs, the required FDM mass <span><math><mrow><msub><mrow><mi>m</mi></mrow><mrow><mi>a</mi></mrow></msub><mo>=</mo><mn>3</mn><mo>.</mo><msubsup><mrow><mn>2</mn></mrow><mrow><mo>−</mo><mn>0</mn><mo>.</mo><mn>6</mn></mrow><mrow><mo>+</mo><mn>0</mn><mo>.</mo><mn>8</mn></mrow></msubsup><mo>×</mo><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mo>−</mo><mn>21</mn></mrow></msup><mspace></mspace><mi>eV</mi></mrow></math></span> is also in conflict with existing Lyman-<span><math><mi>α</mi></math></span> bounds. Our results suggest that FDM cannot provide a consistent explanation for DM cores and imply <span><math><mrow><msub><mrow><mi>m</mi></mrow><mrow><mi>a</mi></mrow></msub><mo>&gt;</mo><mn>2</mn><mo>.</mo><mn>2</mn><mo>×</mo><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mo>−</mo><mn>21</mn></mrow></msup><mspace></mspace><mi>eV</mi></mrow></math></span> at to <span><math><mrow><mn>2</mn><mi>σ</mi></mrow></math></span> CL.</div></div>","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"49 ","pages":"Article 102010"},"PeriodicalIF":5.0,"publicationDate":"2025-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144634481","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":"Optical signatures of hairy black holes surrounded by plasma: Shadows and weak lensing","authors":"Abduqodir Bakhodirov ,&nbsp;Bakhodir Shodikulov ,&nbsp;Farruh Atamurotov ,&nbsp;Ahmadjon Abdujabbarov ,&nbsp;Chen Zhou ,&nbsp;Chengxun Yuan","doi":"10.1016/j.dark.2025.102008","DOIUrl":"10.1016/j.dark.2025.102008","url":null,"abstract":"<div><div>The optical properties around the hairy black hole have been studied in the presence of a plasma medium. The obtained results have shown that the effect of the hairy black hole parameter’s <span><math><mi>a</mi></math></span>, <span><math><msub><mrow><mi>l</mi></mrow><mrow><mi>o</mi></mrow></msub></math></span> and <span><math><mi>Q</mi></math></span> on the deflection angle of light rays around the black hole is perceptible. With an increase in hairs <span><math><mi>a</mi></math></span> and <span><math><msub><mrow><mi>l</mi></mrow><mrow><mi>o</mi></mrow></msub></math></span> of black hole, there is a promotion in the radius of the photon sphere and the radius of the shadow of the central object. However, an increase in primary hair <span><math><mi>Q</mi></math></span> leads to a reduction in the photon sphere and shadow of the hairy black hole, and the effect of plasma on the deflection angle is the opposite. Here, we discuss different types of plasma distributions: uniform <span><math><mrow><msub><mrow><mi>ω</mi></mrow><mrow><mi>e</mi></mrow></msub><mo>=</mo><mi>c</mi><mi>o</mi><mi>n</mi><mi>s</mi><mi>t</mi></mrow></math></span>; Singular Isothermal Sphere medium and nonuniform plasma with <span><math><mrow><msubsup><mrow><mi>ω</mi></mrow><mrow><mi>e</mi></mrow><mrow><mn>2</mn></mrow></msubsup><mo>=</mo><msub><mrow><mi>z</mi></mrow><mrow><mi>o</mi></mrow></msub><mo>/</mo><mi>r</mi></mrow></math></span>. Additionally, the total magnification of the image source due to the gravitational weak lensing has also been considered taking into account the influence of parameters <span><math><mi>a</mi></math></span>, <span><math><msub><mrow><mi>l</mi></mrow><mrow><mi>o</mi></mrow></msub></math></span> and <span><math><mi>Q</mi></math></span> related to hairy spacetime in the presence of plasma around the black hole.</div></div>","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"49 ","pages":"Article 102008"},"PeriodicalIF":5.0,"publicationDate":"2025-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144631189","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":"Dynamical analysis of quantum matter bounces with dark sector mimickers","authors":"Francisco Bento Lustosa,&nbsp;Nelson Pinto-Neto","doi":"10.1016/j.dark.2025.102013","DOIUrl":"10.1016/j.dark.2025.102013","url":null,"abstract":"<div><div>We study the effects of the inclusion of fluids In bounce scenarios driven by an exponential potential scalar field. Most solutions exhibit well known tracking behavior between the fluids and the scalar field. This tracking behavior can model transitions between different phases of cosmic evolution. We will focus on an interesting bouncing model with a dust matter fluid, where the scalar field can drive an early dark energy expanding period with a radiation-like dominated phase just after it, and then tracks the dust matter fluid with energy density compatible with the dark matter energy density. The model is dust dominated in the far past of the contracting phase, and has stiff matter behavior when approaching the singularity, allowing well known quantum bounce transitions to the expanding era. Hence, it is a quantum matter bounce scenario with an inflationary phase together with a smooth transition through a radiation era to matter domination with a possible scalar field dark matter candidate.</div></div>","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"49 ","pages":"Article 102013"},"PeriodicalIF":5.0,"publicationDate":"2025-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144631188","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":"Attempting to circumvent the Ricci-inverse no-go theorem with complexifiable singularities: An emergent Dark Energy model","authors":"Mattia Scomparin","doi":"10.1016/j.dark.2025.102002","DOIUrl":"10.1016/j.dark.2025.102002","url":null,"abstract":"<div><div>Ricci-inverse gravity is a new type of fourth-order gravity theory based on the anti-curvature tensor, that is, the inverse of the Ricci tensor. In this context, we introduce a novel method to circumvent the binding effects of a well-known no-go theorem for cosmic trajectories that cannot smoothly join a decelerated cosmic age with the current accelerated expansion of the universe. We therefore design an emergent class of Ricci-inverse theories whose cosmologies, without falling into no-go singularities, achieve the observed expansion as a stable attractor solution. This new perspective retrains Ricci-inverse cosmologies as viable dark energy models.</div></div>","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"49 ","pages":"Article 102002"},"PeriodicalIF":5.0,"publicationDate":"2025-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144655802","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}