What We Already Know About Quintessence

TL;DR

This paper reviews the conditions for quintessence models to explain cosmic acceleration, highlighting recent developments that allow for dynamic energy domination and kinetic suppression, making our epoch unique.

Contribution

It identifies viable quintessence potentials, like SUGRA, that fit observational bounds and exhibit recent energy domination and kinetic suppression.

Findings

Constant equation of state and inverse power potentials are excluded by supernova data.

SUGRA and similar potentials are consistent with observational constraints.

Our current epoch is special due to recent quintessence energy domination.

Abstract

Good tracking requires significant quintessence energy fraction, even in the past, but a potential that is not yet truly slow-rolling. The supernova bound on cosmic acceleration excludes constant equation of state and inverse power potentials, but allows the SUGRA potential and other good trackers, in which quintessence energy domination and kinetic energy suppression {\em both} began only recently. This makes the time in which we live special in {\em two} respects.