Determining the mechanism behind the current cosmic acceleration constitutes a major question nowadays in theoretical physics. If the dark energy route is taken, this problem may potentially bring to light new insights not only in Cosmology but also in high energy physics theories. Following this approach, we explore in this paper some cosmological consequences of a new time-dependent parameterization for the dark energy equation of state (EoS), which is a well behaved function of the redshift $z$ over the entire cosmological evolution, i.e., $z\in [-1,\infty)$. This parameterization allows us to divide the parametric plane $(w_0,w_1)$ in defined regions associated to distinct classes of dark energy models that can be confirmed or excluded from a confrontation with current observational data. A statistical analysis involving the most recent observations from type Ia supernovae, baryon acoustic oscillation peak, Cosmic Microwave Background shift parameter and Hubble evolution $H(z)$ is performed to check the observational viability of the EoS parameterization here proposed.Comment: 6 pages, 3 figures, LaTe
The accelerated expansion of the Universe is one of the greatest challenges of modern physics. One candidate to explain this phenomenon is a new field called dark energy. In this work we have used the Tsallis nonextensive statistical formulation of the Friedmann equation to explore the BarbozaAlcaniz and Chevalier-Polarski-Linder parametric dark energy models and the Wang-Meng and Dalal vacuum decay models. After that, we have discussed the observational tests and the constraints concerning the Tsallis nonextensive parameter.PACS numbers: 98.80. Es, 98.80.Jk
Based on the relationship between thermodynamics and gravity we propose, with the aid of Verlinde's formalism, an alternative interpretation of the dynamical evolution of the Friedmann-Robertson-Walker Universe. This description takes into account the entropy and temperature intrinsic to the horizon of the universe due to the information holographically stored there through non-gaussian statistical theories proposed by Tsallis and Kaniadakis. The effect of these nongaussian statistics in the cosmological context is change the strength of the gravitational constant.In this paper, we consider the wCDM model modified by the non-gaussian statistics and investigate the compatibility of these non-gaussian modification with the cosmological observations. In order to analyze in which extend the cosmological data constrain these non-extensive statistics, we use type Ia supernovae, baryon acoustic oscillations, Hubble expansion rate function and the linear growth of matter density perturbations data.There are theoretical evidences that the understanding of gravity has been greatly benefited from a possible connection to thermodynamics. Pioneering works of Bekenstein [1] and Hawking [2] have described this issue. For example, quantities as area and mass of black holes are associated with entropy and temperature respectively. Working on this subject, Jacobson [3] interpreted Einstein field equations as a thermodynamic identity. Padmanabhan [4] gave an interpretation of gravity as an equipartition theorem. Recently, Verlinde [5] brought an heuristic derivation of gravity, both Newtonian and relativistic, at least for static spacetime. The equipartition law of energy has also played an important role. The analysis of the dynamics of an inflationary universe ruled out by the entropic gravity concept was investigated in [6]. On the other hand, one can ask: what is the point of view of gravitational models coupled with thermostatistical theories and vice-versa?The concept introduced by Verlinde is analogous to Jacobson's [3] one, who proposed a thermodynamic derivation of Einstein's equations. The result has shown that the gravitation law derived by Newton can be interpreted as an entropic force originated by perturbations in the information "manifold" caused by the motion of a massive body when it moves away from the holographic screen. An holographic screen can be understood as a storage device for information which is constituted by bits. Bits are the smallest units of information. Verlinde used this idea together with the Unruh result [7] and he obtained Newton's second law. The idea of a entropic gravity/cosmology has been extensively investigated in different contexts, see [8,9] for recent results Moreover, assuming the holographic principle together with the equipartition law of energy, the Newton law of gravitation could be derived. The connection between nonextensive statistical theory and the entropic gravity models [10, 11] make us to realize an arguably bridge between nonextensivity and gravity theories. In this paper...
A generalized parameterization w β (z) for the dark energy equation of state (EoS) is proposed and some of its cosmological consequences are investigated. We show that in the limit of the characteristic dimensionless parameter β → +1, 0 and -1 some well-known EoS parameterizations are fully recovered whereas for other values of β the proposed parameterization admits a wider and new range of cosmological solutions. We also discuss possible constraints on the w β (z) parameters from current observational data. PACS numbers: 98.80.Es, 98.80.-k, 98.80.Jk * Electronic address: edesio@on.br † Electronic address: alcaniz@on.br ‡ Electronic address: zhuzh@bnu.edu.cn § Electronic address: raimundosilva@dfte.ufrn.br 1 The possibility ω(z) = −1 still leads to two different routes, i.e., either the so-called quintessence if −1 < ω(z) < −1/3 [2] or phantom fields if ω(z) < −1 [3]. Both cases violate the strong energy condition ρ + 3p > 0, but the latter goes even further and also violates the null energy condition ρ + p > 0 [4].
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.