Constraining Cosmological Dynamics of Scalar-Tensor Models of Dark Energy in Teleparallel Gravity
Abstract
We consider scalar tensor theory in teleparallel gravity by non-minimally coupling of the generic function of the scalar field f(ϕ) to the torsion scalar T. Firstly, we obtain the field equations in this regime, then by considering the FRW homogenous cosmology containing a radiation and non- relativistic matter, with energy densities ρr and ρm, we study its evolution as a dynamical autonomous model of dark energy. We show that the cosmological behavior depends on the coupling function and the potential function. A constant c
We consider scalar tensor theory in teleparallel gravity by non-minimally coupling of the generic function of the scalar field f(ϕ) to the torsion scalar T. Firstly, we obtain the field equations in this regime, then by considering the FRW homogenous cosmology containing a radiation and non- relativistic matter, with energy densities ρr and ρm, we study its evolution as a dynamical autonomous model of dark energy. We show that the cosmological behavior depends on the coupling function and the potential function. A constant coupling ζ leads to the quadratic coupling term f(ϕ) ∝ (ϕ + c)2 and λ = constant gives the power law potential function V (ϕ) ∝ f(ϕ)λ in the scaler field action which is motivated by several mathematical and physical reasons. We study the phase space analysis of these models. We show that λ ≫ 1 is the necessary condition to have radiation era with equation of state and matter phase with equation of state e ≃ 0. Also, the radiation dominated in radiation era and matter dominated in the matter phase can be realized with ≪ 1. Finally, we derive the necessary conditions for the viable cosmological trajectory in this regime.
oupling ζ leads to the quadratic coupling term f(ϕ) ∝ (ϕ + c)2 and λ = constant gives the power law potential function V (ϕ) ∝ f(ϕ)λ in the scaler field action which is motivated by several mathematical and physical reasons. We study the phase space analysis of these models. We show that λ ≫ 1 is the necessary condition to have radiation era with equation of state and matter phase with equation of state e ≃ 0. Also, the radiation dominated in radiation era and matter dominated in the matter phase can be realized with ≪ 1. Finally, we derive the necessary conditions for the viable cosmological trajectory in this regime.