Bouncing cosmology without anisotropy

TL;DR

This paper demonstrates that a smooth, isotropic bounce in the universe's early history can be achieved using a non-linear equation of state combining perfect fluid and dark energy, requiring specific conditions on the equation of state.

Contribution

It introduces a model of bouncing cosmology utilizing a non-linear equation of state with a binary mixture of perfect fluid and dark energy, ensuring isotropy and smoothness.

Findings

A smooth, isotropic bounce is possible with a non-linear equation of state.

Contraction source must have $>1$ (Ekpyrotic matter) and positive pressure dark energy.

The model maintains isotropy during the bounce.

Abstract

Using non-linear equation of state for pressure and density energy, we show that the universe is began with a smooth and isotropic bounce. We use a non-linear equation of state which is a binary mixture of perfect fluid and dark energy. We show that in order to preserve a smooth and isotropic bounce, the source for contraction before the bounce, must have an equation of state with $\omega>1$ (Ekpyrotic matter) and a dark energy with positive pressure.