Gravitational smoothing of kinks on cosmic string loops

TL;DR

This paper investigates how gravitational back reaction influences the shape and evolution of cosmic string loops with kinks, affecting their potential observability and the formation of cusps over their lifetimes.

Contribution

It provides an analysis of gravitational back reaction effects on cosmic string loops with kinks, highlighting conditions under which kinks are straightened or preserved.

Findings

Kinks are not rounded off but may be straightened by back reaction.

Loops with certain symmetries can preserve kinks and evaporate self-similarly.

Example analysis of the rectangular Garfinkle-Vachaspati loop illustrates these effects.

Abstract

We analyze the effect of gravitational back reaction on cosmic string loops with kinks, which is an important determinant of the shape, and thus the potential observability, of string loops which may exist in the universe today. Kinks are not rounded off, but may be straightened out. This means that back reaction will only cause loops with kinks to develop cusps after some potentially large fraction of their lifetimes. In some loops, symmetries prevent even this process, so that the loop evaporates in a self-similar fashion and the kinks are unchanged. As an example, we discuss back-reaction on the rectangular Garfinkle-Vachaspati loop.