Exponential-Potential Scalar Field Universes I: The Bianchi I Models

TL;DR

This paper derives exact solutions for anisotropic Bianchi I universes with exponential-potential scalar fields, showing they typically evolve into power-law inflating universes, with inhomogeneity affecting late-time behavior.

Contribution

It provides the first exact solutions for Bianchi I models with exponential scalar fields and analyzes their late-time dynamics, extending previous isotropic studies.

Findings

Late-time behavior is power-law inflation in most cases.

Inhomogeneity alters the late-time evolution.

Exact solutions are obtained for the Einstein equations in this context.

Abstract

We obtain a general exact solution of the Einstein field equations for the anisotropic Bianchi type I universes filled with an exponential-potential scalar field and study their dynamics. It is shown, in agreement with previous studies, that for a wide range of initial conditions the late-time behaviour of the models is that of a power-law inflating FRW universe. This property, does not hold, in contrast, when some degree of inhomogeneity is introduced, as discussed in our following paper II.