Quintessence scalar field and cosmological constant: Dynamics of a multi-component dark energy model

TL;DR

This paper analyzes a multi-component dark energy model combining a scalar field and a cosmological constant, identifying various stable late-time behaviors and their implications for cosmic evolution.

Contribution

It provides a comprehensive dynamical system analysis of the combined scalar field and cosmological constant model, revealing new stable attractors and early scalar field activity.

Findings

Late-time attractors are either cosmological constant dominated or mixed scalar field and constant.

Scalar field can become active early in the matter era, but after recombination.

Multiple fixed points with different cosmological behaviors identified and analyzed.

Abstract

This study explores the dynamics and phase-space behavior of a multi-component dark energy model, where the dark sector consists of a minimally coupled canonical scalar field and the cosmological constant, using a dynamical system analysis setup for various types of potential for which a general parameterization of the scalar field potentials has been considered. Several fixed points with different cosmological behaviors have been identified. A detailed stability analysis has been done and possible late-time attractors have been found. For this multi-component dark energy model, the late-time attractors are either fully dominated by the cosmological constant or represent a scenario where a combination of the scalar field and the cosmological constant dominates the universe. In this type of model, there is a possibility that the scalar field can become dynamical quite early compared to the standard era of dark energy domination. However, our analysis indicates that this early time contribution of the scalar field occurs deep in the matter-dominated era, not before the recombination era.