Slow-roll freezing quintessence

TL;DR

This paper analyzes the evolution of slow-roll quintessence models with specific potentials, deriving an analytic approximation for the equation of state parameter that matches numerical results and describes a characteristic freezing and thawing behavior.

Contribution

It provides an analytic approximation for the evolution of w in slow-roll quintessence models with nonzero initial velocity, highlighting their freezing and thawing phases.

Findings

Analytic approximation matches numerical evolution of w.

Models exhibit initial freezing followed by slow thawing.

Behavior resembles constant-V models at early times.

Abstract

We examine the evolution of quintessence models with potentials satisfying (V'/V)^2<<1 and V"/V<<1, in the case where the initial field velocity is nonzero. We derive an analytic approximation for the evolution of the equation of state parameter, w, for the quintessence field. We show that such models are characterized by an initial rapid freezing phase, in which the equation of state parameter w decreases with time, followed by slow thawing evolution, for which w increases with time. These models resemble constant-V models at early times but diverge at late times. Our analytic approximation gives results in excellent agreement with exact numerical evolution.