Physics of the Dark Universe最新文献

{"title":"Absorption, scattering, geodesics, shadows and lensing phenomena of black holes in effective quantum gravity","authors":"N. Heidari ,&nbsp;A.A. Araújo Filho ,&nbsp;R.C. Pantig ,&nbsp;A. Övgün","doi":"10.1016/j.dark.2025.101815","DOIUrl":"10.1016/j.dark.2025.101815","url":null,"abstract":"<div><div>In this work, we investigate the signatures of black holes within an effective quantum gravity framework recently proposed in the literature (Cong et al., 2024). We begin by outlining the general setup, highlighting the two distinct models under consideration. This includes a discussion of their general properties, interpretations, and the structure of the event and inner horizons. We then examine the behavior of light in this context, analyzing geodesics, the photon sphere, and shadow formation. To validate our results, we estimate lower bounds for the shadow radius based on observational data from Sgr A<span><math><msup><mrow></mrow><mrow><mo>∗</mo></mrow></msup></math></span> and M87<span><math><msup><mrow></mrow><mrow><mo>∗</mo></mrow></msup></math></span>. Subsequently, we derive the partial radial wave equation for scalar perturbations, enabling us to study the absorption cross-section in both low- and high-frequency regimes. Additionally, we evaluate the greybody factors and provide bounds for both bosonic and fermionic fields. Finally, we present a detailed analysis of gravitational lensing in both the weak and strong deflection limits. For the weak deflection regime, the <em>Gauss–Bonnet</em> theorem is employed, while for the strong deflection limit, the <em>Tsukamoto</em> approach is utilized.</div></div>","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"47 ","pages":"Article 101815"},"PeriodicalIF":5.0,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143155703","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 evidence for elastic interactions in the dark sector","authors":"Jose Beltrán Jiménez ,&nbsp;Dario Bettoni ,&nbsp;David Figueruelo ,&nbsp;Florencia A. Teppa Pannia","doi":"10.1016/j.dark.2024.101761","DOIUrl":"10.1016/j.dark.2024.101761","url":null,"abstract":"<div><div>The increasing quality of cosmological data has revealed some tensions that could be signalling the necessity of incorporating new physics into our cosmological model. One particularly intriguing possibility is the existence of elastic interactions between dark matter and dark energy. Not only do these interactions provide a natural mechanism to relief cosmological tensions, but there is also compelling observational evidence for them, to the extent that a detection could even be claimed. We review the potential of these scenarios in relation to the cosmological tensions and discuss distinctive signatures that can be probed with future data, thus providing a smoking gun for these interactions.</div></div>","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"47 ","pages":"Article 101761"},"PeriodicalIF":5.0,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143156717","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":"Preheating and gravitational waves production in hybrid metric-Palatini model","authors":"Brahim Asfour,&nbsp;Aatifa Bargach,&nbsp;Yahya Ladghami,&nbsp;Ahmed Errahmani,&nbsp;Taoufik Ouali","doi":"10.1016/j.dark.2025.101812","DOIUrl":"10.1016/j.dark.2025.101812","url":null,"abstract":"<div><div>In this study, we investigate the preheating era and the production of gravitational waves during this stage within the Higgs inflation hybrid metric-Palatini framework. In this setup, the Higgs field is supposed to be non-minimally coupled to the Palatini curvature through the coupling constant <span><math><mi>ξ</mi></math></span>. To study the evolution of the preheating process in terms of the reheating, characterized by the equation of state <span><math><mi>ω</mi></math></span>, and inflationary parameters, we use a parameter <span><math><mi>δ</mi></math></span>, which characterizes this process by relating the energy density at the end of inflation to the preheating one. We establish a link between gravitational wave density, preheating duration, and the spectral index by considering different specific values of the gravitational wave density spectrum. Additionally, we compare our results with the sensitivity curves of future experiments, analyzing the impact of preheating duration and the equation of state on the gravitational wave spectrum. We find that the Higgs hybrid metric-Palatini model can effectively explain both preheating and the production of gravitational waves during this era, with results that consistently agree with Planck data in the case where the coupling constant <span><math><mrow><mi>ξ</mi><mo>=</mo><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mo>−</mo><mn>4</mn><mo>.</mo><mn>1</mn></mrow></msup></mrow></math></span>, the equation of state <span><math><mrow><mi>ω</mi><mo>=</mo><mn>1</mn><mo>/</mo><mn>4</mn></mrow></math></span> and the parameter <span><math><mrow><mi>δ</mi><mo>=</mo><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mn>3</mn></mrow></msup></mrow></math></span> or <span><math><mrow><mi>δ</mi><mo>=</mo><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mn>7</mn></mrow></msup></mrow></math></span>.</div></div>","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"47 ","pages":"Article 101812"},"PeriodicalIF":5.0,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143156836","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":"ΛCDM model against redshift-binned data: A mock analysis based on SNIa and Cosmic Chronometers","authors":"Saeed Pourojaghi,&nbsp;Mohammad Malekjani","doi":"10.1016/j.dark.2025.101822","DOIUrl":"10.1016/j.dark.2025.101822","url":null,"abstract":"<div><div>Despite the broad successes of the flat <span><math><mi>Λ</mi></math></span>CDM model and its fitness to the various cosmological observations, it confronts challenges stemming from anomalies in the measurements of the Hubble constant (<span><math><msub><mrow><mi>H</mi></mrow><mrow><mn>0</mn></mrow></msub></math></span>) and the amplitude of matter fluctuations (<span><math><msub><mrow><mi>σ</mi></mrow><mrow><mn>8</mn></mrow></msub></math></span>). These inconsistencies have necessitated a reassessment of the model parameters, with a particular focus on their potential dependence on redshift. This study pioneers a new investigation to probe this redshift dependency by generating mock data simulated from observational data of Type Ia supernovae (SNIa) and cosmic chronometers (CC), thereby increasing the data density in this field. By sorting the data into high-redshift and low-redshift bins, we aim to refine the cosmological constraints on the parameters of the <span><math><mi>Λ</mi></math></span>CDM model and determine whether the noted dependence on redshift is due to a lack of high-redshift observational data or if they signify intrinsic issues within the model itself. Our approach employs the Markov Chain Monte Carlo (MCMC) algorithm to minimize the <span><math><msup><mrow><mi>χ</mi></mrow><mrow><mn>2</mn></mrow></msup></math></span> function, thus tightening the cosmological constraints. Our findings within the mock analysis reveal discrepancies between the values of <span><math><msub><mrow><mi>Ω</mi></mrow><mrow><mi>m</mi><mn>0</mn></mrow></msub></math></span> and <span><math><msub><mrow><mi>H</mi></mrow><mrow><mn>0</mn></mrow></msub></math></span> derived from the mock data bins with high redshift and low redshift, indicating the potential deviation of the standard <span><math><mi>Λ</mi></math></span> CDM cosmology from the high-redshift SNIa and CC data. If this deviation proposes a new physics beyond the standard model, then with better quality future data tracking the new physics, these discrepancies will be statistically significant.</div></div>","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"47 ","pages":"Article 101822"},"PeriodicalIF":5.0,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143100663","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":"Observable signatures of RN black holes with dark matter halos via strong gravitational lensing and constraints from EHT observations","authors":"Niyaz Uddin Molla ,&nbsp;Himanshu Chaudhary ,&nbsp;Salvatore Capozziello ,&nbsp;Farruh Atamurotov ,&nbsp;G. Mustafa ,&nbsp;Ujjal Debnath","doi":"10.1016/j.dark.2024.101804","DOIUrl":"10.1016/j.dark.2024.101804","url":null,"abstract":"&lt;div&gt;&lt;div&gt;We explore the influence of dark matter halos on gravitational lensing produced by electrically charged, spherically symmetric black holes in the strong-field regime. This study delves into the strong gravitational lensing effects within the context of two significant dark matter models: the Universal Rotation Curve Model and the cold dark matter model. Initially, we derive the coefficients for the strong deflection limit and numerically analyze the substantial variations of the deflection angle. Additionally, we present graphical representations of these results. We find that the strong deflection angle, denoted as &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;α&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;D&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt;, increases with the rising charge parameter magnitude &lt;span&gt;&lt;math&gt;&lt;mi&gt;Q&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt; in presence of a dark matter halo. Furthermore, we examine the various astrophysical consequences of the compact objects &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;M&lt;/mi&gt;&lt;mn&gt;8&lt;/mn&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mn&gt;7&lt;/mn&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mo&gt;∗&lt;/mo&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; and &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;S&lt;/mi&gt;&lt;mi&gt;g&lt;/mi&gt;&lt;mi&gt;r&lt;/mi&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mi&gt;A&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mo&gt;∗&lt;/mo&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;, as charged black holes, and compare results with those for other astrophysical black holes such as standard Reissner–Nordström (RN) and Schwarzschild black holes, via strong gravitational lensing observations. From our study, the observations point out that it may be possible to quantitatively differentiate and characterize charged black holes with dark matter halos from astrophysical black holes, such as the standard Reissner–Nordström and Schwarzschild black holes. Finally, We constrain the charge parameter &lt;span&gt;&lt;math&gt;&lt;mi&gt;Q&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt; with the observational data by the Event Horizon Telescope Collaboration for the supermassive black holes &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;M&lt;/mi&gt;&lt;mn&gt;8&lt;/mn&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mn&gt;7&lt;/mn&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mo&gt;∗&lt;/mo&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; and &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;S&lt;/mi&gt;&lt;mi&gt;g&lt;/mi&gt;&lt;mi&gt;r&lt;/mi&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mi&gt;A&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mo&gt;∗&lt;/mo&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;. We constrain the charge parameter &lt;span&gt;&lt;math&gt;&lt;mi&gt;Q&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt; of the charged black holes with universal rotation curve dark matter halo as &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;mo&gt;≤&lt;/mo&gt;&lt;mrow&gt;&lt;mo&gt;|&lt;/mo&gt;&lt;mi&gt;Q&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;366&lt;/mn&gt;&lt;mi&gt;M&lt;/mi&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; for &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;M&lt;/mi&gt;&lt;mn&gt;8&lt;/mn&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mn&gt;7&lt;/mn&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mo&gt;∗&lt;/mo&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;, &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;mo&gt;≤&lt;/mo&gt;&lt;mrow&gt;&lt;mo&gt;|&lt;/mo&gt;&lt;mi&gt;Q&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;586&lt;/mn&gt;&lt;mi&gt;M&lt;/mi&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; for &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;S&lt;/mi&gt;&lt;mi&gt;g&lt;/mi&gt;&lt;mi&gt;r&lt;/mi&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mi&gt;A&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mo&gt;∗&lt;/mo&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;. The charged black hole with cold dark matter halo can be constrained with &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;mo&gt;≤&lt;/mo&gt;&lt;mrow&gt;&lt;mo&gt;|&lt;/mo&gt;&lt;mi&gt;Q&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","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"47 ","pages":"Article 101804"},"PeriodicalIF":5.0,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143155704","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":"Stability analysis of a f(Q) cosmological model along with EBEC dark matter equation of state","authors":"Purnima Zala ,&nbsp;Chetan Likhar ,&nbsp;Aaqid Bhat ,&nbsp;P.K. Sahoo","doi":"10.1016/j.dark.2024.101772","DOIUrl":"10.1016/j.dark.2024.101772","url":null,"abstract":"<div><div>This work aim to investigate the mysterious components of the universe, specifically dark energy and dark matter. To characterize the origin of dark energy, we investigate alternative gravity theory to general relativity exhibiting a flat background framework that is based entirely on non-metricity. Specifically, we consider the <span><math><mrow><mi>f</mi><mrow><mo>(</mo><mi>Q</mi><mo>)</mo></mrow></mrow></math></span> functional from as <span><math><mrow><mi>f</mi><mrow><mo>(</mo><mi>Q</mi><mo>)</mo></mrow><mo>=</mo><mi>γ</mi><msup><mrow><mi>Q</mi></mrow><mrow><mn>2</mn></mrow></msup></mrow></math></span>, where <span><math><mi>γ</mi></math></span> serves as a free parameter in the model, whereas to describe the dark matter, we assume the relation <span><math><mrow><mi>p</mi><mo>=</mo><mi>α</mi><mi>ρ</mi><mo>+</mo><mi>β</mi><msup><mrow><mi>ρ</mi></mrow><mrow><mn>2</mn></mrow></msup></mrow></math></span> known as the Extended Bose–Einstein Condensate (EBEC) dark matter equation of state. We obtain the motion equations and the continuity relation incorporating both dark matter and dark energy fluid, along with an interaction term, particularly, <span><math><mrow><mi>I</mi><mo>=</mo><mn>3</mn><mi>b</mi><mi>H</mi><mi>ρ</mi></mrow></math></span>, where <span><math><mrow><mi>b</mi><mo>&gt;</mo><mn>0</mn></mrow></math></span> represents the strength of the energy exchange from dark energy to dark matter. Further, we invoke a set of dimensionless phase space variables that enables us to transform the dynamics of the cosmological system into an autonomous system. Then we perform a detail stability analysis of the considered cosmological model, and we conclude that the cosmological model under consideration effectively captures the dynamics of the universe from a decelerated matter-dominated era to a stable phase of accelerated expansion.</div></div>","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"47 ","pages":"Article 101772"},"PeriodicalIF":5.0,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143095537","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":"Frequency shifts induced by light scalar fields","authors":"Christian Käding","doi":"10.1016/j.dark.2024.101788","DOIUrl":"10.1016/j.dark.2024.101788","url":null,"abstract":"<div><div>Light scalar fields are frequently used in modern physics, for example, as candidates for dark energy or dark matter. Open quantum dynamical effects, like frequency shifts, induced by such fields in probe particles used in interferometry experiments might open up new perspectives for constraining such models. In this article, we consider a probe scalar particle as a rough approximation for an atom in matter wave interferometry and discuss the frequency shifts induced by interactions with an environment comprising either one of two screened scalar field models: chameleons or symmetrons. For the <span><math><mrow><mi>n</mi><mo>=</mo><mo>−</mo><mn>4</mn></mrow></math></span> chameleon, we revise a previously obtained expression for the induced frequency shift, but confirm that it can likely not be used to obtain new constraints. However, for symmetrons, we find that induced frequency shifts have the potential to tightly constrain previously unreachable parts of the parameter space.</div></div>","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"47 ","pages":"Article 101788"},"PeriodicalIF":5.0,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143155698","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Geodesics and thermodynamics of Einstein-Power-Yang–Mills AdS black holes","authors":"Saheb Soroushfar ,&nbsp;Ali Iloon Kashkooli ,&nbsp;Hoda Farahani ,&nbsp;Prabir Rudra ,&nbsp;Behnam Pourhassan","doi":"10.1016/j.dark.2024.101800","DOIUrl":"10.1016/j.dark.2024.101800","url":null,"abstract":"<div><div>In this paper, we investigate the geodesic equations in the spacetime of Einstein-Power–Yang–Mills anti-de Sitter (AdS) black holes. We obtain analytical solutions to the geodesic equations using Weierstrass elliptic and Kleinian sigma hyperelliptic functions. We classify possible orbits such as flyby, bound, terminating bound, and terminating escape orbits based on the analytical solutions and effective potential. We also briefly study the thermodynamics of these black holes, plotting the horizon radius versus mass to demonstrate the possibility of having one or three horizons. We derive expressions for temperature, entropy, pressure, and volume, and interpret the results. We find that there is a possibility of van der Waals-like behavior for the holographic dual fluid corresponding to these Einstein-Power-Yang–Mills AdS black holes.</div></div>","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"47 ","pages":"Article 101800"},"PeriodicalIF":5.0,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143155701","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The distances of high-redshift Type Ia supernovae as possible evidence for a variable speed of light","authors":"Si-Na Wei","doi":"10.1016/j.dark.2024.101779","DOIUrl":"10.1016/j.dark.2024.101779","url":null,"abstract":"<div><div>Exploration of the variable speed of light as an alternative explanation for the observed dimming of high-redshift Type Ia supernovae (SNe Ia) was conducted, a phenomenon traditionally interpreted as evidence for dark energy. To begin, differences in distance modulus between models that include dark energy and those that do not were derived based on the assumption of dark energy’s existence. Next, calculations were made on how the absolute magnitudes of SNe Ia at different redshifts change with variations in the speed of light. Results indicate that a decrease in the speed of light with increasing redshift could account for the observed dimming of SNe Ia without requiring the introduction of dark energy. Furthermore, estimates suggest that the time required for the speed of light to increase by 1 m/s in the current universe would be less than 186 years.</div></div>","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"47 ","pages":"Article 101779"},"PeriodicalIF":5.0,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143099708","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":"Analysis of initial singularity admitting viable bounce models","authors":"M. Sharif ,&nbsp;M. Zeeshan Gul ,&nbsp;Nusrat Fatima","doi":"10.1016/j.dark.2024.101760","DOIUrl":"10.1016/j.dark.2024.101760","url":null,"abstract":"<div><div>This research investigates the non-singular cosmic bounce models corresponding to Bianchi type-I spacetime in the framework of symmetric teleparallel theory. A specific functional form of this modified theory is used to examine the dynamics of bouncing cosmology. This study formulates the modified field equations and considers various parametric values to obtain feasible solutions. We examine the behavior of different cosmic bounce models corresponding to different scale factors and Hubble parameters, which resolves the big bang singularity as these parameters support the cyclic universe, there is a transition from an earlier contraction phase to another expansion phase. Furthermore, we investigate the behavior of energy density and pressure to comprehend the attributes of dark energy. The comprehensive analysis of equation of state parameter is also studied to determine the evolutionary eras of the universe. Our results indicate that the symmetric teleparallel theory describes cosmic expansion near the bouncing point.</div></div>","PeriodicalId":48774,"journal":{"name":"Physics of the Dark Universe","volume":"47 ","pages":"Article 101760"},"PeriodicalIF":5.0,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143100015","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}