Self-Similar Evaporation of a Rigidly-Rotating Cosmic String Loop

TL;DR

This paper investigates the weak-field gravitational back-reaction on a rigidly-rotating cosmic string loop, demonstrating that it undergoes self-similar evaporation while maintaining its shape.

Contribution

It provides the first detailed calculation of the self-acceleration and back-reaction effects on this specific cosmic string loop, showing its evolution by self-similar shrinking.

Findings

Loop experiences finite net back-reaction over an oscillation period.

Back-reaction causes uniform shrinkage, preserving the loop's shape.

Loop evolves through self-similar evaporation.

Abstract

The gravitational back-reaction on a certain type of rigidly-rotating cosmic string loop, first discovered by Allen, Casper and Ottewill, is studied at the level of the weak-field approximation. The near-field metric perturbations are calculated and used to construct the self-acceleration vector of the loop. Although the acceleration vector is divergent at the two kink points on the loop, its net effect on the trajectory over a single oscillation period turns out to be finite. The net back-reaction on the loop over a single period is calculated using a method due to Quashnock and Spergel, and is shown to induce a uniform shrinkage of the loop while preserving its original shape. The loop therefore evolves by self-similar evaporation.