Dynamical description of a quintom cosmological model nonminimally coupled with gravity
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Regular Article - Theoretical Physics
Dynamical description of a quintom cosmological model nonminimally coupled with gravity Mihai Marciua Faculty of Physics, University of Bucharest, 405 Atomi¸stilor, POB MG-11, 077125 Bucharest-M˘agurele, Romania
Received: 4 August 2020 / Accepted: 13 September 2020 © The Author(s) 2020
Abstract In this work we have studied a cosmological model based on a quintom dark energy model non-minimally coupled with gravity, endowed with a specific potential energy of the exponential squared type. For this specific type of potential energy and non-minimal coupling, the dynamical properties are analyzed and the corresponding cosmological effects are discussed. Considering the linear stability method, we have investigated the dynamical properties of the phase space structure, determining the physically acceptable solutions. The analysis showed that in this model we can have various cosmological epochs, corresponding to radiation, matter domination, and de Sitter eras. Each solution is investigated from a physical and cosmological point of view, obtaining possible constraints of the model’s parameters. In principle the present cosmological setup represent a possible viable scalar tensor theory which can explain various transitional effects related to the behavior of the dark energy equation of state and the evolution of the Universe at large scales.
1 Introduction In the present days the cosmological context reached a golden age epoch by overturning the fundamental concepts related to the evolution and the major constituents of the Universe, fracturing our understanding of time and space. The accelerated expansion of the Universe [1] represent an enigma to theorists and cosmologists, with deep ramifications in various branches of physics. The basic evidence of the accelerated expansion has been probed through various astrophysical studies [2,3] which included observation from type Ia supernovae [4,5], baryon acoustic oscillations [6–10] and cosmic microwave background radiation [11–13]. The simplest scenario of dark energy is represented by the cosmological constant [14] added to the Einstein field equation, a proposal which lead to a constant equation of state for the a e-mail:
dark energy sector. In order to explain the dynamical evolution of the dark energy equation of state various theoretical directions have been proposed [15–21] in the form of single or multiple scalar fields, minimally or non-minimally coupled with gravity or other possible invariants [22]. The behavior of the dark energy equation of state [23–25] represents an important aspect when constructing a viable scalar tensor theory of gravitation [26,27] which can explain various physical quantities associated to the known Universe. In this case the strange issue related to the crossing over the phantom divide line (the cosmological constant barrier) [25, 28] by the dark energy equation of state has been explained by adopting a possible extension to the Einstein–Hilbert action which adds two scalar fields [29,30], an a
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