The stochastic background from cosmic (super)strings: popcorn and (Gaussian) continuous regimes

TL;DR

This paper analyzes the stochastic gravitational wave background from cosmic (super)strings, focusing on popcorn and continuous regimes, and assesses the detectability with current and future gravitational wave detectors.

Contribution

It introduces a detailed study of both popcorn and continuous gravitational wave backgrounds from cosmic strings across multiple detectors, highlighting their complementarity and potential for parameter estimation.

Findings

Popcorn background can be as pronounced as continuous background in some parameter regions.

Detection of popcorn regime can improve confidence in stochastic background signals.

The study provides sensitivity estimates for LIGO/Virgo, LISA, ET, and PTA.

Abstract

In the era of the next generation of gravitational wave experiments a stochastic background from cusps of cosmic (super)strings is expected to be probed and, if not detected, to be significantly constrained. A popcorn-like background can be, for part of the parameter space, as pronounced as the (Gaussian) continuous contribution from unresolved sources that overlap in frequency and time. We study both contributions from unresolved cosmic string cusps over a range of frequencies relevant to ground based interferometers, such as LIGO/Virgo second generation (AdLV) and Einstein Telescope (ET) third generation detectors, the space antenna LISA and Pulsar Timing Arrays (PTA). We compute the sensitivity (at $2 \sigma$ level) in the parameter space for AdLV, ET, LISA and PTA. We conclude that the popcorn regime is complementary to the continuous background. Its detection could therefore enhance confidence in a stochastic background detection and possibly help determine fundamental string parameters such as the string tension and the reconnection probability.