More accurate gravitational wave backgrounds from cosmic strings

TL;DR

This paper develops a new method to accurately compute the gravitational wave background from cosmic strings with evolving shapes, showing that previous estimates overpredicted the signals by up to 30%.

Contribution

It introduces a general procedure for calculating GWBs from backreacted cosmic strings with evolving shapes, improving accuracy over prior models.

Findings

GWBs are 5-30% lower than previous predictions.

The method applies to a range of string tensions and frequencies.

Results inform detection prospects with current and future GW detectors.

Abstract

We derive a general procedure for calculating the gravitational wave background (GWB) from cosmic string loops whose typical shape evolves over time, as in gravitational backreaction. Using the results of a large-scale study of numerical gravitational backreaction on Nambu-Goto cosmic string loops, we construct GWBs of backreacted cosmic strings for a range of tensions and frequencies of cosmological interest, and compare them to current and upcoming gravitational wave detectors. The GWBs are lower than prior predictions by anywhere from a few percent to around 30\%, depending on the frequency and tension in question.