Quintessence

TL;DR

This paper reviews different types of quintessence models for dark energy, using dynamical systems methods to analyze their global behavior and relationships, providing new insights into late-time cosmic acceleration.

Contribution

It introduces a dynamical systems approach to analyze various quintessence models, including new potentials, clarifying their properties and initial conditions.

Findings

Dynamical systems methods reveal global features of quintessence models.

New scalar field potentials are analyzed within this framework.

Clear visualizations illustrate relationships among different quintessence types.

Abstract

Recent observations suggest that the accelerated expansion of the Universe at late times is caused by a temporally changing dark energy component, rather than the constant one in the standard $\Lambda$CDM scenario. In this context quintessence, i.e. a canonical scalar field minimally coupled to gravity, plays a prominent role. There are, however, three main types of quintessence models: thawing quintessence, scaling freezing quintessence, and tracking quintessence. Dynamical systems reformulations of the field equations for a broad set of scalar field potentials, including some new ones, allow us to use dynamical systems methods to derive global and asymptotic features, visualised in bounded state space pictures clearly illustrating the relationships and properties of the different types of quintessence, clarifying initial data issues, and yielding simple and accurate approximations.