Dark Energy Fluid with Time-Dependent, Inhomogeneous Equation of State

TL;DR

This paper investigates a cosmological model with a time-dependent, inhomogeneous fluid equation of state, revealing cyclic universe behaviors and potential future singularities through analytical solutions of the equations of motion.

Contribution

It introduces a novel inhomogeneous, oscillating EoS in cosmology and analyzes its effects on universe dynamics and singularity formation.

Findings

Discovery of quasi-periodic universe cycles

Identification of conditions leading to future singularities

Analytical solutions for the universe's evolution

Abstract

The four-dimensional Friedman flat universe, filled with an ideal fluid with a linear (oscillating) inhomogeneous equation of state (EoS) depending on time, is studied. The equations of motion are solved. It is shown that in some cases there appears a quasi-periodic universe, which repeats the cycles of phantom-type space acceleration. The appearance of future singularities resulting from various choices for the input parameters is discussed.