Exact Solutions and Constraints on the Dark Energy Model in FRW Universe

Joseph, Albin; Saha, Rajib

doi:10.48550/arxiv.1912.06782

Cited by 1 publication

(1 citation statement)

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“…Exponential potential: V (φ) = V0e −λφ As a second example of a string type configuration, we will consider the configuration generated by an exponential type potential, with V (φ) = V 0 e −λφ , where V 0 and λ > 0 are constants. The solutions of the gravitational field equations for different scalar field models with exponential potentials have been intensively investigated in the recent physical literature, including the cases of both homogeneous and inhomogeneous scalar fields [70][71][72][73][74][75][76][77]. In four-dimensional effective Kaluza-Klein or string-type theories an exponential potential is generated from the compactification of the higher dimensions [78].…”

Section: Specific Cosmic String Solutionsmentioning

confidence: 99%

Cosmic stringlike objects in hybrid metric-Palatini gravity

Harko,

Lobo,

da Silva

2020

Preprint

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We consider static and cylindrically symmetric interior string solutions in the scalar-tensor representation of the hybrid metric-Palatini modified theory of gravity. As a first step in our study, we obtain the gravitational field equations and further simplify the analysis by imposing Lorentz invariance along the t and z axes, which reduces the number of unknown metric tensor components to a single function. In this case, the general solution of the field equations can be obtained, for an arbitrary form of the scalar field potential, in an exact closed parametric form, with the scalar field φ taken as a parameter. We consider in detail several exact solutions of the field equations, corresponding to a null and constant potential, and to a power-law potential of the form V (φ) = V0φ 3/4 , in which the behavior of the scalar field, metric tensor component and string tension can be described in a simple mathematical form. We also investigate the string models with exponential and Higgs type scalar field potentials by using numerical methods. In this way we obtain a large class of novel stable stringlike solutions in the context of hybrid metric-Palatini gravity, in which the basic parameters, such as the scalar field, metric tensor and string tension, depend essentially on the initial values of the scalar field, and of its derivative, along the string axis.

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