Cosmic strings and strings in gravitational waves

TL;DR

This paper derives exact solutions for strings with Nambu action sharing symmetries in various gravitational backgrounds, enhancing understanding of string dynamics in cosmological and gravitational wave spacetimes.

Contribution

It provides new exact solutions for strings in Friedmann, Kasner, and gravitational wave backgrounds, using symmetry-based dimensional reduction.

Findings

Exact solutions for straight and circle-like strings in Friedmann backgrounds

Solutions for straight strings in Kasner backgrounds

String configurations in gravitational wave metrics

Abstract

We consider strings with the Nambu action as extremal surfaces in a given space-time, thus, we ignore their back reaction. Especially, we look for strings sharing one symmetry with the underlying space-time. If this is a non-null symmetry, the problem of determining the motion of the string can be dimensionally reduced. We get exact solutions for the following cases: straight and circle-like strings in a Friedmann background, straight strings in an anisotropic Kasner background, different types of strings in the metric of a gravitational wave. The solutions will be discussed.