Backreaction on an infinite helical cosmic string

TL;DR

This paper analytically investigates how gravitational wave emission affects an infinite helical cosmic string, revealing length loss, phase advancement, and implications for cosmic string network structures.

Contribution

It provides the first analytical calculation of gravitational backreaction on a helical cosmic string, including length loss and phase shift effects.

Findings

Length of the string decreases at a rate matching emitted gravitational power.

The string's oscillation phase advances due to backreaction effects.

The results support understanding of cosmic string network evolution.

Abstract

To understand the properties of a possible cosmic string network requires knowledge of the structures on long strings, which control the breaking off of smaller loops. These structures are influenced by backreaction due to gravitational wave emission. To gain an understanding of this process, we calculate the effect of gravitational backreaction on the "helical breather": an infinite cosmic string with a helical standing wave. We do the calculation analytically to first order in the amplitude of the oscillation. Our results for the rate of loss of length agree with the total power emitted from this system as calculated by Sakellariadou. We also find a rotation of the generators of the string that leads to an advancement of the phase of the oscillation in addition to that produced by the loss of length.