Isotropisation of Bianchi class A models with a minimally coupled scalar field and a perfect fluid

TL;DR

This paper investigates the conditions under which anisotropic Bianchi class A cosmological models with a scalar field and perfect fluid evolve towards isotropy, emphasizing scalar field dominance and accelerated expansion.

Contribution

It identifies the necessary conditions for isotropisation in Bianchi models with a scalar field, including scalar field dominance and specific geometric and dynamic properties.

Findings

Isotropisation occurs only when the scalar field dominates the energy content.

The universe develops flat spacelike sections during isotropisation.

Accelerated expansion is a key feature in the isotropisation process.

Abstract

We look for the necessary conditions allowing the Universe isotropisation in presence of a minimally coupled and massive scalar field with a perfect fluid. We conclude that it arises only when the Universe is scalar field dominated, leading to flat spacelike sections and accelerated expansion, and examine the case of a SUGRA theory.