Physics of the Dark Universe最新文献

{"title":"A search for sterile neutrinos in interacting dark energy models using DESI baryon acoustic oscillations and DES supernovae data","authors":"Lu Feng ,&nbsp;Tian-Nuo Li ,&nbsp;Guo-Hong Du ,&nbsp;Jing-Fei Zhang ,&nbsp;Xin Zhang","doi":"10.1016/j.dark.2025.101935","DOIUrl":"10.1016/j.dark.2025.101935","url":null,"abstract":"<div><div>Sterile neutrinos can influence the evolution of the universe, and thus cosmological observations can be used to search for sterile neutrinos. In this study, we utilized the latest baryon acoustic oscillations data from DESI, combined with the cosmic microwave background data from Planck and the five-year supernova data from DES, to constrain the interacting dark energy (IDE) models involving both cases of massless and massive sterile neutrinos. We consider four typical forms of the interaction term <span><math><mrow><mi>Q</mi><mo>=</mo><mi>β</mi><mi>H</mi><msub><mrow><mi>ρ</mi></mrow><mrow><mi>de</mi></mrow></msub></mrow></math></span>, <span><math><mrow><mi>Q</mi><mo>=</mo><mi>β</mi><mi>H</mi><msub><mrow><mi>ρ</mi></mrow><mrow><mi>c</mi></mrow></msub></mrow></math></span>, <span><math><mrow><mi>Q</mi><mo>=</mo><mi>β</mi><msub><mrow><mi>H</mi></mrow><mrow><mn>0</mn></mrow></msub><msub><mrow><mi>ρ</mi></mrow><mrow><mi>de</mi></mrow></msub></mrow></math></span>, and <span><math><mrow><mi>Q</mi><mo>=</mo><mi>β</mi><msub><mrow><mi>H</mi></mrow><mrow><mn>0</mn></mrow></msub><msub><mrow><mi>ρ</mi></mrow><mrow><mi>c</mi></mrow></msub></mrow></math></span>, respectively. Our analysis indicates that the current data provide only a hint of the existence of massless sterile neutrinos (as dark radiation) at about the <span><math><mrow><mn>1</mn><mi>σ</mi></mrow></math></span> level. In contrast, no evidence supports the existence of massive sterile neutrinos. Furthermore, in IDE models, the inclusion of (massless/massive) sterile neutrinos has a negligible impact on the constraint of the coupling parameter <span><math><mi>β</mi></math></span>. The IDE model of <span><math><mrow><mi>Q</mi><mo>=</mo><mi>β</mi><mi>H</mi><msub><mrow><mi>ρ</mi></mrow><mrow><mi>c</mi></mrow></msub></mrow></math></span> with sterile neutrinos does not favor an interaction. However, the other three IDE models with sterile neutrinos support an interaction in which dark energy decays into dark matter.</div></div>","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"48 ","pages":"Article 101935"},"PeriodicalIF":5.0,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143906499","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 finite value of strange quark mass (ms≠0) and baryon number density (n) on the structure of strange stars","authors":"Pradip Kumar Chattopadhyay,&nbsp;Debadri Bhattacharjee","doi":"10.1016/j.dark.2025.101927","DOIUrl":"10.1016/j.dark.2025.101927","url":null,"abstract":"&lt;div&gt;&lt;div&gt;This study investigates the influence of non-zero strange quark mass &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;m&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;s&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; and baryon number density &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mi&gt;n&lt;/mi&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; on the properties, and maximum mass of strange stars. An exact relativistic solution of Einstein field equations is obtained using Tolman-IV potential and modified MIT bag model equation of state, &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;p&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;r&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mfrac&gt;&lt;mrow&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;3&lt;/mn&gt;&lt;/mrow&gt;&lt;/mfrac&gt;&lt;mrow&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mi&gt;ρ&lt;/mi&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mn&gt;4&lt;/mn&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mi&gt;B&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mo&gt;′&lt;/mo&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/mrow&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;, where &lt;span&gt;&lt;math&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mi&gt;B&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mo&gt;′&lt;/mo&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;/math&gt;&lt;/span&gt; depends on bag constant &lt;span&gt;&lt;math&gt;&lt;mi&gt;B&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt;, &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;m&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;s&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt;, and &lt;span&gt;&lt;math&gt;&lt;mi&gt;n&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt;. In line with CERN’s findings, the transition from hadronic matter to quark–gluon plasma at high densities requires a more dynamic EoS. Unlike the standard MIT bag model with fixed &lt;span&gt;&lt;math&gt;&lt;mi&gt;B&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt;, the present approach employs Woods–Saxon parametrisation for &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;B&lt;/mi&gt;&lt;mrow&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mi&gt;n&lt;/mi&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/mrow&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;, improving the description of phase transitions. Solutions of TOV equations indicate that for &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;m&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;s&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;, the maximum mass reaches &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;mo&gt;.&lt;/mo&gt;&lt;mn&gt;01&lt;/mn&gt;&lt;mspace&gt;&lt;/mspace&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;M&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mo&gt;⊙&lt;/mo&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; with a radius of 10.96 Km at &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;n&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;66&lt;/mn&gt;&lt;mspace&gt;&lt;/mspace&gt;&lt;mi&gt;f&lt;/mi&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mi&gt;m&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mn&gt;3&lt;/mn&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;. Increasing &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;m&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;s&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt; reduces these values. Notably, a correlation exists between &lt;span&gt;&lt;math&gt;&lt;mi&gt;n&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt; and &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;m&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;s&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt;, where the hadron–quark transition occurs at higher densities with increasing &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;m&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;s&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt;. Stability analysis suggests that a chosen &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;n&lt;/mi&gt;&lt;mspace&gt;&lt;/mspace&gt;&lt;mrow&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;578&lt;/mn&gt;&lt;mspace&gt;&lt;/mspace&gt;&lt;mi&gt;f&lt;/mi&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mi&gt;m&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mn&gt;3&lt;/mn&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/mrow&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; with &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;B&lt;/mi&gt;&lt;mrow&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mi&gt;n&lt;/mi&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/mrow&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;70&lt;/mn&gt;&lt;mspace&gt;&lt;/mspace&gt;&lt;mi&gt;M&lt;/mi&gt;&lt;mi&gt;e&lt;/mi&gt;&lt;mi&gt;V&lt;/mi&gt;&lt;mo&gt;/&lt;/mo&gt;&lt;mi&gt;f&lt;/mi&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mi&gt;m&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;3&lt;/mn&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;/mrow","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"48 ","pages":"Article 101927"},"PeriodicalIF":5.0,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143891519","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 model in the framework of f(R,Lm) gravity with quadratic equation of state parameter","authors":"Vinod Kumar Bhardwaj ,&nbsp;Saibal Ray","doi":"10.1016/j.dark.2025.101930","DOIUrl":"10.1016/j.dark.2025.101930","url":null,"abstract":"<div><div>In this study, we explore a transitioning cosmological model of universe’s expansion in <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></mrow></mrow></math></span> gravity. The quadratic type of equation of state parameter in the form <span><math><mrow><mi>ω</mi><mo>=</mo><mo>−</mo><mn>1</mn><mo>+</mo><mi>α</mi><mrow><mo>(</mo><mn>1</mn><mo>+</mo><mi>z</mi><mo>)</mo></mrow><mo>+</mo><mi>β</mi><msup><mrow><mrow><mo>(</mo><mn>1</mn><mo>+</mo><mi>z</mi><mo>)</mo></mrow></mrow><mrow><mn>2</mn></mrow></msup></mrow></math></span>, where <span><math><mi>α</mi></math></span> and <span><math><mi>β</mi></math></span> are constants, is considered to determine the explicit solution of field equations and derive Hubble parameter in term of redshift <span><math><mi>z</mi></math></span>. The model parameters are estimated taking observational datasets of BAO, Pantheon, and CC using MCMC analysis. Some dynamical properties like EOS parameter, energy density, pressure, and deceleration parameter are described. The cosmographic parameter like statefinders (<span><math><mrow><mi>r</mi><mo>,</mo><mi>s</mi></mrow></math></span>), jerk parameter (<span><math><mi>j</mi></math></span>) etc are also thoroughly explained. The energy conditions are also examined to validate the viability of the proposed model. We observe a transition redshift at <span><math><mrow><msub><mrow><mi>z</mi></mrow><mrow><mi>t</mi></mrow></msub><mo>=</mo><mn>0</mn><mo>.</mo><mn>94</mn><msubsup><mrow><mn>2</mn></mrow><mrow><mo>−</mo><mn>0</mn><mo>.</mo><mn>164</mn></mrow><mrow><mo>+</mo><mn>0</mn><mo>.</mo><mn>112</mn></mrow></msubsup></mrow></math></span> with the present value of deceleration parameter <span><math><mrow><msub><mrow><mi>q</mi></mrow><mrow><mn>0</mn></mrow></msub><mo>=</mo><mo>−</mo><mn>0</mn><mo>.</mo><mn>481</mn><msubsup><mrow><mn>5</mn></mrow><mrow><mo>−</mo><mn>0</mn><mo>.</mo><mn>0096</mn></mrow><mrow><mo>+</mo><mn>0</mn><mo>.</mo><mn>0362</mn></mrow></msubsup></mrow></math></span>.</div></div>","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"48 ","pages":"Article 101930"},"PeriodicalIF":5.0,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143891422","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 dark matter halo and albedo effect on the out-of-plane motion in the generalized photogravitational RTBP","authors":"Raj Mal Jat,&nbsp;Ram Kishor","doi":"10.1016/j.dark.2025.101940","DOIUrl":"10.1016/j.dark.2025.101940","url":null,"abstract":"<div><div>This research investigates the impact of a dark matter halo and albedo effect in the context of existence and linear stability analysis of out-of-plane equilibrium points under the frame of a generalized photogravitational restricted three body problem. The system considers the out-of-plane motion of an infinitesimal mass under the combined influence of the dark matter halo, radiation pressure force due to radiating primary and albedo from oblate secondary. To compute the out-of-plane equilibrium points, an approximation method in the form of power series expansion and the classical Newton–Raphson method are utilized followed by linear stability test is performed. A significant influence of the dark matter halo is observed in the context of positions of out-of-plane equilibrium points as well as of the stability region. Two symmetric out-of-plane equilibrium points are identified in the <span><math><mrow><mi>x</mi><mi>z</mi></mrow></math></span>-plane and are examined across the defined ranges of assumed perturbing parameters <span><math><mi>γ</mi></math></span>, <span><math><mi>κ</mi></math></span>, <span><math><mi>ρ</mi></math></span> and <span><math><msub><mrow><mi>M</mi></mrow><mrow><mi>h</mi></mrow></msub></math></span> except for <span><math><mrow><mi>ρ</mi><mo>=</mo><mfrac><mrow><mi>μ</mi></mrow><mrow><mi>κ</mi><mrow><mo>(</mo><mn>1</mn><mo>−</mo><mi>μ</mi><mo>)</mo></mrow></mrow></mfrac></mrow></math></span> and <span><math><mrow><mi>κ</mi><mo>=</mo><mfrac><mrow><mi>μ</mi></mrow><mrow><mi>ρ</mi><mrow><mo>(</mo><mn>1</mn><mo>−</mo><mi>μ</mi><mo>)</mo></mrow></mrow></mfrac></mrow></math></span>. Moreover, these points either shift their respective quadrants or align to the <span><math><mi>z</mi></math></span>-axis at critical values of <span><math><mi>ρ</mi></math></span> and <span><math><mi>κ</mi></math></span> and vanish under certain conditions. Further, linear stability analysis indicates that these equilibrium points are unstable for all values of perturbing parameters (including mass parameter <span><math><mi>μ</mi></math></span>) within their defined ranges. The obtained results will help to study similar problem with different perturbations.</div></div>","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"48 ","pages":"Article 101940"},"PeriodicalIF":5.0,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143928420","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":"Thermodynamical properties of nonsingular universe","authors":"Ahmad Sheykhi ,&nbsp;Leila Liravi ,&nbsp;Kimet Jusufi","doi":"10.1016/j.dark.2025.101931","DOIUrl":"10.1016/j.dark.2025.101931","url":null,"abstract":"<div><div>We disclose the thermodynamical properties of the apparent horizon in a nonsingular universe. We take into account the zero-point length correction to the gravitational potential and derive the modified entropy expression that includes zero-point length correction terms. We apply the first law of thermodynamics on the apparent horizon as well as the emergent gravity scenario to derive the modified Friedmann equations. Further, we examine the time evolution of the total entropy, including the entropy of the apparent horizon and the matter field entropy inside the horizon and find out that the generalized second law of thermodynamics is satisfied. We also investigate the cosmological implications of the modified cosmology through zero-point length. We observe that the zero-point length correction does not change the general profile of the universe evolution, however, it shifts the time of the phase transition in a universe filled with matter and cosmological constant. We explore the age of the universe for our model and observe that the predicted age of the universe becomes larger compared to the standard cosmology. By calculating the explicit form of Ricci and Kretschmann invariants, we confirm that in our model, the initial singularity of the universe is removed. This is an expected result, because the main motivation for considering zero-point length correction in the gravitational potential is to remove singularity at the origin.</div></div>","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"48 ","pages":"Article 101931"},"PeriodicalIF":5.0,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143886430","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 signals of self-interacting dark matter core collapse in Hi-rich galaxies","authors":"Demao Kong,&nbsp;Hai-Bo Yu","doi":"10.1016/j.dark.2025.101939","DOIUrl":"10.1016/j.dark.2025.101939","url":null,"abstract":"<div><div>We analyze rotation curves of five <span>Hi</span>-rich galaxies recently discovered with MeerKAT. These galaxies exhibit sharply rising rotation curves, while their baryonic components are not dynamically dominant, suggesting that their dark matter halos have high inner densities. When fitting the standard Navarro–Frenk–White (NFW) halo model, four galaxies require extremely high halo concentrations, exceeding the cosmological median by <span><math><mrow><mn>5</mn><mi>σ</mi></mrow></math></span>. In contrast, self-interacting dark matter (SIDM) halos in the core-collapse phase naturally account for the high densities in these galaxies. For halos with masses around <span><math><mrow><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mn>11</mn></mrow></msup><mspace></mspace><msub><mrow><mi>M</mi></mrow><mrow><mo>⊙</mo></mrow></msub></mrow></math></span>, those in cosmic filaments exhibit concentrations consistent with the cosmological average, while halos in cosmic nodes show relatively higher concentrations that align with the SIDM fits but remain insufficient for the NFW fits. Our analysis indicates that these <span>Hi</span>-rich galaxies may have formed in cosmic nodes of dark matter with significant self-interactions.</div></div>","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"48 ","pages":"Article 101939"},"PeriodicalIF":5.0,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143928421","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":"Observational constraints on cosmological parameters in the Bianchi type III Universe with f(R,T) gravity theory","authors":"Pranjal Sarmah,&nbsp;Umananda Dev Goswami","doi":"10.1016/j.dark.2025.101932","DOIUrl":"10.1016/j.dark.2025.101932","url":null,"abstract":"<div><div>Bianchi type III (BIII) metric is an interesting anisotropic model for studying cosmic anisotropy as it has an additional exponential term multiplied to a directional scale factor. Thus, the cosmological parameters obtained for this BIII metric with the conventional energy–momentum tensor within the framework of a modified gravity theory and the estimation of their values with the help of Hubble, Pantheon plus and other observational data may provide some new information in cosmic evolution. In this work, we have studied the BIII metric under 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 theory and estimated the values of the cosmological parameters for three different models of this gravity theory by using the Bayesian technique. In our study, we found that all the models show consistent results with the current observations but show deviations in the early stage of the Universe. In one model we have found a sharp discontinuity in the radiation-dominated phase of the Universe. Hence through this study, we have found that some 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> gravity models may not be suitable for studying evolutions and early stages of the Universe in the BIII metric even though they show consistent results with the current observations.</div></div>","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"48 ","pages":"Article 101932"},"PeriodicalIF":5.0,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143895791","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 study of wormhole solution using MIT bag parameter B in the framework of f(R,Lm,T) gravity","authors":"Moreshwar Tayde,&nbsp;Debasmita Mohanty,&nbsp;P.K. Sahoo","doi":"10.1016/j.dark.2025.101937","DOIUrl":"10.1016/j.dark.2025.101937","url":null,"abstract":"<div><div>In this study, we explore the existence of traversable wormholes supported by strange quark matter, modeled using the MIT bag equation of state, 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></mrow></math></span> gravity. We analyze wormhole solutions considering three distinct functional forms of the <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></mrow></math></span> model and adopting two specific shape functions with a logarithmic redshift function. The energy conditions at the throat of the wormhole, located at radius <span><math><msub><mrow><mi>r</mi></mrow><mrow><mn>0</mn></mrow></msub></math></span>, are examined to assess the influence of the parameters <span><math><mi>β</mi></math></span>, <span><math><msub><mrow><mi>γ</mi></mrow><mrow><mn>1</mn></mrow></msub></math></span> and <span><math><msub><mrow><mi>γ</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span> on the violations of the energy conditions, particularly the null energy condition. Furthermore, a stability analysis was performed using the Tolman–Oppenheimer–Volkoff (TOV) equation, which confirmed the stability of the obtained wormhole solutions. Lastly, we investigate the active gravitational mass of the wormhole to gain further insight into its physical viability. We have concluded that our wormhole solutions are stable and traversable, with NEC violation due to modified gravity. Despite exotic matter, the wormhole maintains a positive active mass, resembling the gravitational influence of ordinary matter. Our findings contribute to the broader understanding of wormhole solutions in extended theories of gravity and their astrophysical implications.</div></div>","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"48 ","pages":"Article 101937"},"PeriodicalIF":5.0,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143895792","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":"Generalized logarithmic modification of Barrow–Tsallis entropy can alleviate the Hubble tension","authors":"M. Yarahmadi,&nbsp;A. Salehi","doi":"10.1016/j.dark.2025.101923","DOIUrl":"10.1016/j.dark.2025.101923","url":null,"abstract":"<div><div>This study investigates the generalized Barrow–Tsallis entropy, characterized by the quantum-gravitational deformation parameter <span><math><mi>Δ</mi></math></span>, the Tsallis nonextensivity parameter <span><math><mi>q</mi></math></span>, and the logarithmic correction parameter <span><math><mi>α</mi></math></span>, as a framework for addressing the Hubble tension within a modified cosmological model. By incorporating the Barrow entropy, <span><math><mrow><mi>S</mi><mo>∝</mo><msup><mrow><mi>A</mi></mrow><mrow><mi>Δ</mi></mrow></msup></mrow></math></span>, and Tsallis entropy, <span><math><mrow><msub><mrow><mi>S</mi></mrow><mrow><mi>q</mi></mrow></msub><mo>=</mo><mfrac><mrow><mi>A</mi></mrow><mrow><mn>4</mn><mi>G</mi></mrow></mfrac><mo>+</mo><mover><mrow><mi>α</mi></mrow><mrow><mo>̃</mo></mrow></mover><msub><mrow><mo>ln</mo></mrow><mrow><mi>q</mi></mrow></msub><mfrac><mrow><mi>A</mi></mrow><mrow><mn>4</mn><mi>G</mi></mrow></mfrac><mo>+</mo><mover><mrow><mi>β</mi></mrow><mrow><mo>̃</mo></mrow></mover></mrow></math></span>, we derive modified Friedmann equations in a Friedmann–Robertson–Walker (FRW) universe, introducing an effective dark energy component. The model is constrained using a comprehensive combination of observational datasets, including Planck 2018 Cosmic Microwave Background (CMB) data, Baryon Acoustic Oscillations (BAO), Cosmic Chronometers (CC), Pantheon Supernovae, and Planck lensing data. Our analysis reveals that the inclusion of these datasets significantly mitigates the Hubble tension, achieving a <span><math><mrow><mn>1</mn><mo>.</mo><mn>21</mn><mi>σ</mi></mrow></math></span> agreement with Planck 2018 and <span><math><mrow><mn>0</mn><mo>.</mo><mn>98</mn><mi>σ</mi></mrow></math></span> with the R22 local measurement. The parameter <span><math><mi>α</mi></math></span> indicates subtle deviations from classical entropy, while <span><math><mi>Δ</mi></math></span> is tightly constrained to <span><math><mrow><mi>Δ</mi><mo>&lt;</mo><mn>0</mn><mo>.</mo><mn>002</mn></mrow></math></span>, suggesting minimal quantum-gravitational corrections on cosmological scales. Furthermore, the Tsallis parameter <span><math><mi>q</mi></math></span> stabilizes at <span><math><mrow><mi>q</mi><mo>≈</mo><mn>0</mn><mo>.</mo><mn>41</mn></mrow></math></span>, demonstrating the robustness of the model in fitting observational data. This work demonstrates that the generalized entropy framework serves as a compelling alternative to the standard <span><math><mi>Λ</mi></math></span>CDM model, offering competitive performance in reconciling the Hubble tension and explaining late-time cosmic acceleration.</div></div>","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"48 ","pages":"Article 101923"},"PeriodicalIF":5.0,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143886329","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":"Modified f(R,T) theory in light of gravitational wave standard sirens","authors":"Mahnaz Asghari,&nbsp;Ahmad Sheykhi","doi":"10.1016/j.dark.2025.101928","DOIUrl":"10.1016/j.dark.2025.101928","url":null,"abstract":"<div><div>In this paper, we ponder observational constraints on the modified <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 the gravitational action is a function of Ricci scalar <span><math><mi>R</mi></math></span> plus the trace of the energy–momentum tensor <span><math><mi>T</mi></math></span>, regarding the functional form <span><math><mrow><mi>f</mi><mrow><mo>(</mo><mi>R</mi><mo>,</mo><mi>T</mi><mo>)</mo></mrow><mo>=</mo><mi>R</mi><mo>+</mo><mn>2</mn><mi>f</mi><mrow><mo>(</mo><mi>T</mi><mo>)</mo></mrow></mrow></math></span> with <span><math><mrow><mi>f</mi><mrow><mo>(</mo><mi>T</mi><mo>)</mo></mrow><mo>=</mo><mn>8</mn><mi>π</mi><mi>G</mi><mi>λ</mi><mi>T</mi></mrow></math></span>. For this purpose, we utilize recently available data, including cosmic microwave background, weak lensing, supernovae, baryon acoustic oscillations, and redshift-space distortions measurements, together with forcasted gravitational wave (GW) data from Laser Interferometer Space Antenna (LISA). Notably, we examine the potentiality of simulated GW data from LISA standard sirens (SS) sources to enhance cosmological constraints on 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 parameters. In this regard, we create three LISA mock catalogs, namely Pop III, Delay, and No Delay, to improve the obtained constraints on cosmological parameters 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 from current observations. Numerical analysis reveals that mock GW data from LISA SS sources make marginal improvements on constraining 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 cosmological parameters.</div></div>","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"48 ","pages":"Article 101928"},"PeriodicalIF":5.0,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143886328","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}