Exact inhomogeneous Einstein-Maxwell-Dilaton cosmologies

TL;DR

This paper develops solution generating methods to construct exact inhomogeneous and anisotropic cosmological models within string theory, revealing diverse singularity behaviors and late-time evolution involving gravitational, dilatonic, and electromagnetic waves.

Contribution

It introduces new techniques for generating exact inhomogeneous Einstein-Maxwell-Dilaton cosmologies, including explicit solutions with Gowdy-type universes and analysis of their asymptotic behaviors.

Findings

Exact inhomogeneous solutions with Gowdy symmetry obtained.

Near-singularity behavior exhibits spatially varying Kasner form.

Late-time evolution characterized by a universe with weakly interacting waves.

Abstract

We present solution generating techniques which permit to construct exact inhomogeneous and anisotropic cosmological solutions to a four-dimensional low energy limit of string theory containing non-minimally interacting electromagnetic and dilaton fields. Some explicit homogeneous and inhomogeneous cosmological solutions are constructed. For example, inhomogeneous exact solutions presenting Gowdy - type EMD universe are obtained. The asymptotic behaviour of the solutions is investigated. The asymptotic form of the metric near the initial singularity has a spatially varying Kasner form. The character of the space-time singularities is discussed. The late evolution of the solutions is described by a background homogeneous and anisotropic universe filled with weakly interacting gravitational, dilatonic and electromagnetic waves.