Stability Analysis of Anisotropic Inflationary Cosmology

TL;DR

This paper investigates the stability of an anisotropic inflationary universe in a string cosmology model, showing that it tends to evolve towards an isotropic flat universe under certain conditions.

Contribution

It provides a stability analysis of anisotropic inflationary solutions in string cosmology, demonstrating their tendency to evolve into isotropic universes.

Findings

Accelerating expansion solutions are stable against dilaton and axion perturbations.

The universe tends to evolve from anisotropic to isotropic space.

Stable against anisotropic spatial perturbations.

Abstract

The stability analysis of an anisotropic inflationary universe of the four dimensional Neveu-Schwarz--Neveu-Schwarz string model with a nonvanishing cosmological constant is discussed in this paper. The accelerating expansion solution found earlier is shown to be stable against the perturbations with respect to the dilaton and axion fields once the dilaton field falls close to the local minimum of the symmetry-breaking potential. This indicates that the Bianchi I space tends to evolve to an isotropic flat Friedmann-Robertson-Walker space. This expanding solution is also shown to be stable against the perturbation with respect to anisotropic spatial directions.