Tilted String Cosmologies

TL;DR

This paper uses string theory symmetries to generate new tilted Bianchi type VI_h cosmological models with dynamic dilaton fields, revealing their asymptotic plane wave states and extending to inhomogeneous Bianchi type III models.

Contribution

It introduces a method to produce tilted string cosmologies from known solutions, including inhomogeneous generalizations, and analyzes their asymptotic behaviors.

Findings

Models evolve towards plane wave solutions asymptotically.

Dilaton field varies on homogeneous surfaces.

Inhomogeneous Bianchi type III models are constructed.

Abstract

Global symmetries of the string effective action are employed to generate tilted, homogeneous Bianchi type VI_h string cosmologies from a previously known stiff perfect fluid solution to Einstein gravity. The dilaton field is not constant on the surfaces of homogeneity. The future asymptotic state of the models is interpreted as a plane wave and is itself an exact solution to the string equations of motion to all orders in the inverse string tension. An inhomogeneous generalization of the Bianchi type III model is also found.