Physics of the Dark Universe最新文献

{"title":"Anisotropic compact stars under quintessence field with vanishing gravitational complexity factor","authors":"S. Khan ,&nbsp;Javlon Rayimbaev ,&nbsp;Sarvar Iskandarov ,&nbsp;Aybek Seytov ,&nbsp;Inomjon Ibragimov ,&nbsp;Sokhibjan Muminov","doi":"10.1016/j.dark.2026.102220","DOIUrl":"10.1016/j.dark.2026.102220","url":null,"abstract":"<div><div>This work studies the construction of anisotropic self-gravitating star models influenced by a surrounding quintessence field described by a parameter <em>ω_q</em> with <span><math><mrow><mo>−</mo><mn>1</mn><mo>&lt;</mo><msub><mi>ω</mi><mi>q</mi></msub><mo>&lt;</mo><mo>−</mo><mfrac><mn>1</mn><mn>3</mn></mfrac></mrow></math></span>, under the theoretical requirement of a vanishing gravitational complexity factor. The complexity-free constraint, originally proposed as a measure of the structural inhomogeneity and pressure anisotropy of relativistic stellar fluids, is employed to obtain astrophysically relevant solutions of general relativistic field equations. By considering a suitable metric potential, we derive exact expressions for the matter density, principal stresses, and anisotropy factor. The influence of the quintessence field on stellar structure is analyzed in detail, highlighting its role in tuning the pressure anisotropy and energy distribution within the stellar distribution. To ensure realistic stellar modeling, we examine central regularity, positivity of density and principal stresses, energy conditions, causality, and stability requirements. Furthermore, matching conditions with the exterior spacetime are imposed to determine the unknown constants. The resulting stellar configurations are shown to be consistent with observational data of compact stars, thereby demonstrating that the combined effects of the quintessence field and the vanishing complexity condition provide an elegant framework for modeling anisotropic relativistic configuration.</div></div>","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"51 ","pages":"Article 102220"},"PeriodicalIF":6.4,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146077979","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":"Dual impact of matter coupling on LMC X-4 pulsar observations and stability","authors":"Asifa Ashraf ,&nbsp;Tayyab Naseer ,&nbsp;Hammad Afzal ,&nbsp;Chengxun Yuan ,&nbsp;Ozodbek Rahimov ,&nbsp;Ahmadjon Abdujabbarov","doi":"10.1016/j.dark.2026.102230","DOIUrl":"10.1016/j.dark.2026.102230","url":null,"abstract":"<div><div>This study examines the behavior of compact astrophysical objects within a matter-geometry coupled <em>f</em>(<em>R</em>) gravity model. The modified field equations are expressed for a static interior spacetime with an anisotropic matter distribution. Applying two well-defined radial components of the metric ansatz and anisotropic pressures allows for analytical solutions to these equations. In both theoretical models, integrating the differential equations introduces constants, which are fixed using boundary conditions. Furthermore, the condition of null radial pressure at the boundary is used to determine these constants. Additionally, we visually assess certain important features that ensure the physical acceptability of the proposed model and support our analysis with observational data from LMC X-4. Our theoretical research shows that both models meet the physical viability and stability requirements. Further, our investigation also contributes to the knowledge of how the modified gravity model influences the interior structure of compact stars, paving the way for future studies.</div></div>","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"51 ","pages":"Article 102230"},"PeriodicalIF":6.4,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146077972","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":"Late-time cosmology in Weyl-type f(Q, T) modified gravity: Analytic background solutions and observational constraints from H(z), Pantheon+, and DESI","authors":"Aylin Çalışkan","doi":"10.1016/j.dark.2026.102231","DOIUrl":"10.1016/j.dark.2026.102231","url":null,"abstract":"&lt;div&gt;&lt;div&gt;We study the late-time cosmological implications of Weyl-type &lt;em&gt;f&lt;/em&gt;(&lt;em&gt;Q, T&lt;/em&gt;) modified gravity in a spatially flat FLRW background. Working in Weyl geometry, where non-metricity is sourced by a gauge field &lt;em&gt;w&lt;sub&gt;μ&lt;/sub&gt;&lt;/em&gt;, we enforce the vanishing Weyl scalar condition &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mover&gt;&lt;mi&gt;R&lt;/mi&gt;&lt;mo&gt;¯&lt;/mo&gt;&lt;/mover&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; through a Lagrange multiplier, which yields modified field equations containing both a Proca-like vector contribution and a matter-geometry coupling via &lt;em&gt;f&lt;/em&gt;(&lt;em&gt;Q, T&lt;/em&gt;). By adopting the linear ansatz &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;Q&lt;/mi&gt;&lt;mo&gt;,&lt;/mo&gt;&lt;mi&gt;T&lt;/mi&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/mrow&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mi&gt;α&lt;/mi&gt;&lt;mi&gt;Q&lt;/mi&gt;&lt;mo&gt;+&lt;/mo&gt;&lt;mfrac&gt;&lt;mi&gt;β&lt;/mi&gt;&lt;mrow&gt;&lt;mn&gt;6&lt;/mn&gt;&lt;msup&gt;&lt;mi&gt;κ&lt;/mi&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/msup&gt;&lt;/mrow&gt;&lt;/mfrac&gt;&lt;mi&gt;T&lt;/mi&gt;&lt;mo&gt;+&lt;/mo&gt;&lt;mi&gt;γ&lt;/mi&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; and a homogeneous Weyl vector &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;msub&gt;&lt;mi&gt;w&lt;/mi&gt;&lt;mi&gt;μ&lt;/mi&gt;&lt;/msub&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mrow&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mi&gt;ψ&lt;/mi&gt;&lt;mrow&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mi&gt;t&lt;/mi&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;0&lt;/mn&gt;&lt;mo&gt;,&lt;/mo&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/mrow&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; (so that &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;6&lt;/mn&gt;&lt;msup&gt;&lt;mi&gt;ψ&lt;/mi&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/msup&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;), we derive the generalized Friedmann equations and close the system under the approximation &lt;em&gt;λ&lt;/em&gt; ≃ &lt;em&gt;κ&lt;/em&gt;&lt;sup&gt;2&lt;/sup&gt;. The Weyl constraint admits the branch &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;ψ&lt;/mi&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mi&gt;H&lt;/mi&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;, and consistency with the generalized Proca equation selects the massless effective mode &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;msubsup&gt;&lt;mi&gt;m&lt;/mi&gt;&lt;mrow&gt;&lt;mrow&gt;&lt;mi&gt;e&lt;/mi&gt;&lt;/mrow&gt;&lt;mi&gt;f&lt;/mi&gt;&lt;mi&gt;f&lt;/mi&gt;&lt;/mrow&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/msubsup&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;, fixing &lt;em&gt;α&lt;/em&gt; and leaving (&lt;em&gt;β, γ&lt;/em&gt;) as the relevant phenomenological parameters. For a dust sector (&lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;p&lt;/mi&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;), the dynamics reduces to a Riccati-type equation that can be integrated analytically, leading to a closed-form expression for the Hubble function &lt;em&gt;H&lt;/em&gt;(&lt;em&gt;z&lt;/em&gt;) and well-defined viability conditions (notably &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;β&lt;/mi&gt;&lt;mo&gt;≠&lt;/mo&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; and &lt;em&gt;H&lt;/em&gt;&lt;sup&gt;2&lt;/sup&gt;(&lt;em&gt;z&lt;/em&gt;) ≥ 0). We then confront the model with current late-time data using an affine-invariant MCMC analysis with cosmic chronometer &lt;em&gt;H&lt;/em&gt;(&lt;em&gt;z&lt;/em&gt;) measurements, Pantheon+ SNe Ia, and DESI BAO. The combined dataset yields &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;msub&gt;&lt;mi&gt;H&lt;/mi&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;/msub&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;67.86&lt;/mn&gt;&lt;mo&gt;±&lt;/mo&gt;&lt;mn&gt;0.37&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;, &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;β&lt;/mi&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;mo&gt;.&lt;/mo&gt;&lt;msubsup&gt;&lt;mn&gt;27&lt;/mn&gt;&lt;mrow&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mn&gt;0.13&lt;/mn&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mo&gt;+&lt;/mo&gt;&lt;mn&gt;0.11&lt;/mn&gt;&lt;/mrow&gt;&lt;/msubsup&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;, and &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;γ&lt;/mi&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mn&gt;1.8&lt;/mn&gt;&lt;mo&gt;×&lt;/mo&gt;&lt;msup&gt;&lt;mn&gt;10&lt;/mn&gt;&lt;mn&gt;4&lt;/mn&gt;&lt;/msup&gt;&lt;mo&gt;±&lt;/mo&gt;&lt;mn&gt;1.0&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;, with a goodness of fit comparable to ΛCDM (&lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;msubsup&gt;&lt;mi&gt;χ&lt;/mi&gt;&lt;mrow","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"51 ","pages":"Article 102231"},"PeriodicalIF":6.4,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146077976","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":"Search for spatial coincidence between magnetars and IceCube detected neutrinos","authors":"Fathima Shifa M․ ,&nbsp;Shantanu Desai","doi":"10.1016/j.dark.2026.102234","DOIUrl":"10.1016/j.dark.2026.102234","url":null,"abstract":"<div><div>We implement a search for spatial coincidence between high energy neutrinos detected by the IceCube neutrino detector (using the publicly available 10-year muon track data) and 37 magnetars, including six extragalactic sources. We use the unbinned maximum likelihood method for our analysis. We do not find any such spatial association between any of the known magnetars and IceCube-detected neutrinos. Therefore, we conclude that none of the known galactic or extragalactic magnetars contribute to the diffuse neutrino flux observed in IceCube. A stacked analysis also does not show a statistically significant excess.</div></div>","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"51 ","pages":"Article 102234"},"PeriodicalIF":6.4,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146077973","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":"Predictive one-zero with vanishing sub-trace texture in neutrino mass matrix in light of dark matter and neutrinoless double beta decay","authors":"Ankush Choudhary ,&nbsp;Sangeeta Dey ,&nbsp;Rishu Verma ,&nbsp;Manoj Kumar ,&nbsp;B.C. Chauhan ,&nbsp;Mahadev Patgiri","doi":"10.1016/j.dark.2026.102228","DOIUrl":"10.1016/j.dark.2026.102228","url":null,"abstract":"<div><div>In this work, we investigate a predictive class of neutrino mass matrices characterized by one texture zero and one vanishing sub-trace within the framework of the scotogenic model, wherein neutrino masses, dark matter, and neutrinoless double beta decay are intrinsically correlated. We analyze twelve viable texture structures—namely <em>B</em>_1,4,5, <span><math><msub><mi>C</mi><mrow><mn>1</mn><mo>,</mo><mn>2</mn><mo>,</mo><mo>…</mo><mo>,</mo><mn>5</mn></mrow></msub></math></span>, <em>D</em>_4,5, and <em>F</em>_5,6—and examine their implications for the effective Majorana mass (|<em>M_ee</em>|) governing neutrinoless double beta decay (0<em>νββ</em>). Remarkably, all non-zero entries of the neutrino mass matrix can be parametrized in terms of this effective Majorana mass, establishing a direct theoretical link between low-energy observables and high-scale parameters of the model. Among the twelve textures, eleven predict dark matter masses of order TeV and yield correlated bounds on |<em>M_ee</em>|—making them testable in current and forthcoming 0<em>νββ</em> experiments—while the textures <em>D</em>₄ and <em>F</em>_5,6 exhibit comparatively weaker correlations. In contrast, the texture <em>C</em>₅ is excluded due to its requirement of unrealistically large Yukawa couplings and its inability to realize dark matter in the TeV regime. Our analysis thus identifies a subset of predictive neutrino mass textures that consistently relate dark matter phenomenology and neutrinoless double beta decay observables within the scotogenic paradigm.</div></div>","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"51 ","pages":"Article 102228"},"PeriodicalIF":6.4,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146077977","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 remedy of the trans-Planckian censorship problem with smooth slow-roll to power-law inflation transitions in scalar field theory","authors":"S.D. Odintsov ,&nbsp;V.K. Oikonomou","doi":"10.1016/j.dark.2026.102236","DOIUrl":"10.1016/j.dark.2026.102236","url":null,"abstract":"<div><div>It is known that if the standard slow-roll inflation is followed by a power-law inflationary regime, then the trans-Planckian modes may be safely be contained in the Hubble horizon and never exit it during inflation. In this work we investigate how to realize a smooth transition between a slow-roll and a power-law inflationary regime in the context of single scalar field inflation. As we show it is possible to realize such a smooth transition by generalizing the kinetic energy of single scalar field in the form <span><math><mrow><msup><mover><mi>ϕ</mi><mo>˙</mo></mover><mn>2</mn></msup><mo>=</mo><mi>β</mi><mrow><mo>(</mo><mi>ϕ</mi><mo>)</mo></mrow><mi>V</mi><mrow><mo>(</mo><mi>ϕ</mi><mo>)</mo></mrow></mrow></math></span>, where <em>β</em>(<em>ϕ</em>) is some appropriate function of the scalar field. Using two distinct approaches we show that it is possible to realize a smooth transition from a slow-roll to a power-law inflationary regime, and the two approaches produce identical results regarding the slow-roll regime. Also we show that the slow-roll regime is quite short, about <em>N</em> ∼ 30 <em>e</em>-foldings, with the flatness and horizon problems being solved with the synergistic effect of the two inflationary patches. The slow-roll era is found to be compatible with the Atacama Cosmology Telescope data.</div></div>","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"51 ","pages":"Article 102236"},"PeriodicalIF":6.4,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146077974","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":"Emergence of dark energy from topology and chiral spinors","authors":"J. Lorca Espiro ,&nbsp;Yerko Vásquez ,&nbsp;M. Le Delliou","doi":"10.1016/j.dark.2026.102227","DOIUrl":"10.1016/j.dark.2026.102227","url":null,"abstract":"<div><div>Under the existence of a massless spinor with respect to the total connection in a spacetime modeled as a Lorentzian manifold with internal boundaries, such as finite volume semi-classical Black Holes, we show that a topological mechanism naturally induces terms in the Einstein-Cartan gravitational action that can be interpreted as General Relativity with dark energy This may alleviate the problems of dark energy.. The topological information is carried by a harmonic 1-form associated to the first co-holomology group of the spacetime, which induces a spacetime contortion acting on the horizontal bundle.</div></div>","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"51 ","pages":"Article 102227"},"PeriodicalIF":6.4,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146077978","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":"Images of black holes in the center of Moore dark matter halo","authors":"Yang Cao ,&nbsp;Benrong Mu ,&nbsp;Jun Tao ,&nbsp;Xuetao Yang","doi":"10.1016/j.dark.2026.102235","DOIUrl":"10.1016/j.dark.2026.102235","url":null,"abstract":"<div><div>This paper explores the observational appearance of black holes surrounded by the Moore dark matter halo, utilizing the celestial sphere and accretion disks as light sources. We can obtain the equations for circular orbits by employing the weak-field expansion approximation of the black hole metric within a Moore dark matter halo. The study explores the variations in the visual characteristics of black holes when observed from different observational points within the celestial sphere model. For both rotating and stationary accretion disks, we investigated the effects of the radius and characteristic density of the Moore dark matter halo on observable phenomena, while examining the angular dependence in both types of disks. Our investigation shows that in rotating accretion disks, the blue shift effect of photons becomes more prominent as the observation angle increases.</div></div>","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"52 ","pages":"Article 102235"},"PeriodicalIF":6.4,"publicationDate":"2026-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146116670","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":"Implications of f(R) gravity on late-time cosmic structure growth through a complete description of density perturbations","authors":"Miguel Barroso Varela ,&nbsp;Álvaro de la Cruz-Dombriz","doi":"10.1016/j.dark.2026.102232","DOIUrl":"10.1016/j.dark.2026.102232","url":null,"abstract":"<div><div>We provide insight about the full form of the equations for matter density perturbations and the scalar Bardeen metric potentials in general <em>f</em>(<em>R</em>) theories of gravity. When considering viable modifications to the standard ΛCDM background, the full scale-dependent equations for the metric perturbations are provided and are shown to match the ones obtained with the quasistatic approximation. We investigate the impact of the <span><math><mrow><mi>n</mi><mo>=</mo><mn>2</mn></mrow></math></span> Hu-Sawicki model on the late-time growth of structures. We find that updated late-time growth of structure data imposes <span><math><mrow><mrow><mo>|</mo></mrow><msub><mi>f</mi><msub><mi>R</mi><mn>0</mn></msub></msub><mrow><mo>|</mo><mo>≲</mo></mrow><msup><mn>10</mn><mrow><mo>−</mo><mn>6</mn></mrow></msup><mo>−</mo><msup><mn>10</mn><mrow><mo>−</mo><mn>5</mn></mrow></msup></mrow></math></span> and thus conclude that the Hu-Sawicki <em>f</em>(<em>R</em>) model contributes no significant phenomenology at both background and perturbative level beyond the effective cosmological constant encompassed in its definition. This conclusion points to the survival of the present tension between early and late measurements of <em>σ</em>₈, as the Hu-Sawicki model can only worsen this issue or at best reproduce the results from the current concordance cosmological model. The generalized perturbative method showcased in this work can be applied to more elaborate <em>f</em>(<em>R</em>) models to isolate genuine higher-order signatures beyond the quasistatic approximation.</div></div>","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"51 ","pages":"Article 102232"},"PeriodicalIF":6.4,"publicationDate":"2026-01-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146022823","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 constraints on neutrino masses in a second-order CPL dark energy model","authors":"Shubham Barua,&nbsp;Shantanu Desai","doi":"10.1016/j.dark.2026.102229","DOIUrl":"10.1016/j.dark.2026.102229","url":null,"abstract":"<div><div>Recent DESI results indicate a strong preference for dynamical dark energy (DE) when baryon acoustic oscillation (BAO) measurements are combined with supernovae (SNe) and cosmic microwave background (CMB) data using the Chevallier-Polarski-Linder (CPL) parameterization. We analyze the exponential (EXP) parameterization, which introduces a second-order correction to CPL. We determine and compare the 95% upper bounds on the sum of neutrino masses for three dark energy (DE) models—ΛCDM, CPL, and EXP—across four neutrino mass hierarchies (1 massive/2 massless, degenerate, normal, inverted) and multiple dataset combinations (CMB + BAO, CMB + BAO + PantheonPlus, CMB + BAO + DESY5), employing both Bayesian and frequentist frameworks with physical lower limits from oscillation experiments (0.059 eV and 0.11 eV). Our results show that CPL yields tighter ( ≲ 10%) bounds compared to EXP. We further confirm earlier findings that neutrino mass constraints are only mildly sensitive to the assumed hierarchy and that the frequentist bounds are tighter than Bayesian ones. Furthermore, the imposed oscillation lower limits, the datasets used and the DE parameterizations play a crucial role in the inferred cosmological neutrino mass bounds. For the datasets, hierarchies, and DE parameterizations considered, we find no statistically significant evidence for nonzero neutrino mass consistent with oscillation lower limits.</div></div>","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"51 ","pages":"Article 102229"},"PeriodicalIF":6.4,"publicationDate":"2026-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146022821","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}