Gravitational Wave Bursts from Cosmic Superstring Reconnections

TL;DR

This paper calculates gravitational wave bursts from cosmic superstring reconnections, finding they are undetectable by current and future detectors despite optimistic parameters.

Contribution

It introduces a method to compute gravitational wave signals from superstring reconnections using the string path integral approach.

Findings

Bursts are below detection thresholds of Advanced LIGO.

Even optimistic parameters yield undetectable signals.

The stochastic background from these events is also undetectable.

Abstract

We compute the gravitational waveform produced by cosmic superstring reconnections. This is done by first constructing the superstring reconnection trajectory, which closely resembles that of classical, instantaneous reconnection but with the singularities smoothed out due to the string path integral. We then evaluate the graviton vertex operator in this background to obtain the burst amplitude. The result is compared to the detection threshold for current and future gravitational wave detectors, finding that neither bursts nor the stochastic background would be detectable by Advanced LIGO. This disappointing but anticipated conclusion holds even for the most optimistic values of the reconnection probability and loop sizes.