The oscillating dark energy: future singularity and coincidence problem

TL;DR

This paper explores oscillating dark energy models that unify early inflation and late acceleration, address the coincidence problem, and analyze potential future singularities in the universe.

Contribution

It introduces oscillating dark energy models in fluid and scalar-tensor forms, showing their ability to unify cosmic acceleration phases and solve the coincidence problem.

Findings

Oscillating dark energy can unify inflation and late-time acceleration.

Models describe transitions between different cosmic eras.

Finite-time future singularities are possible in oscillating phantom universes.

Abstract

We consider the oscillating dark energy with periodic equation of state in two equivalent formulations: ideal fluid or scalar-tensor theory. It is shown that such dark energy suggests the natural way for the unification of early-time inflation with late-time acceleration. We demonstrate how it describes the transition from deceleration to acceleration or from non-phantom to phantom era and how it solves the coincidence problem. The occurence of finite-time future singularity for the oscillating (phantom) universe is also investigated.