Dark energy with time-dependent equation of state

TL;DR

This paper investigates a flat universe with a time-dependent, oscillating equation of state, revealing that such models can lead to quasi-periodic cycles of accelerated expansion, including phantom-like phases.

Contribution

It introduces and solves models with a linear, oscillating inhomogeneous EoS, demonstrating cyclic universe behaviors not previously detailed.

Findings

Discovery of quasi-periodic universe cycles

Identification of phantom-type acceleration phases

Solutions to equations of motion with oscillating EoS

Abstract

The accelerating Friedmann flat universe, filled with an ideal fluid with a linear (oscillating) inhomogeneous equation of state (EoS) depending on time, is reviewed. The equations of motions are solved. It is shown that in some cases there appears a quasi-periodic universe, which repeats the cycles of phantom-type space acceleration.