Three steps to accelerated expansion

TL;DR

This paper analyzes the evolution of a non-minimally coupled scalar field cosmology using dynamical systems theory, identifying key universe stages and deriving the equation of state parametrization directly from the model.

Contribution

It introduces a comprehensive dynamical systems framework for scalar field cosmology with non-minimal coupling, deriving epoch-specific equations of state without prior assumptions.

Findings

Identified fixed points for radiation, matter, and quintessence domination.

Derived explicit formulas for the effective equation of state at different epochs.

Formulated the $w(z)$ parametrization directly from dynamical equations.

Abstract

We study the dynamics of a non-minimally coupled scalar field cosmology with a potential function. We use the framework of dynamical systems theory to investigate all evolutional paths admissible for all initial conditions. Additionally, we assume the presence of barotropic matter and show that the dynamics can be formulated in terms of an autonomous dynamical system. We have found fixed points corresponding to three main stages of the evolution of the universe, namely, radiation, matter and quintessence domination epochs. Using the linearization of the dynamical systems in the vicinity of the critical points we explicitly obtain formulas determining the effective equation of state parameter for the universe at different epochs. In our approach the form of $w(z)$ parametrisation is derived directly from the dynamical equations rather than postulated {\it a priori}.