Comparison of cosmic string and superstring models to NANOGrav 12.5-year results

We compare the spectrum of the stochastic gravitational wave background produced in several models of cosmic strings with the common-spectrum process recently reported by NANOGrav. We discuss theoretical uncertainties in computing such a background, and show that despite such uncertainties, cosmic strings remain a good explanation for the potential signal, but the consequences for cosmic string parameters depend on the model. Superstrings could also explain the signal, but only in a restricted parameter space where their network behavior is effectively identical to that of ordinary cosmic strings.

Automated summary

This study compares the spectrum of stochastic gravitational wave background produced in various models of cosmic strings and discusses the theoretical uncertainties in computing such a background. Despite the uncertainties, cosmic strings are seen as a plausible explanation for the potential signal, with the consequences for cosmic string parameters depending on the specific model. Superstrings could also explain the signal, but only within a restricted parameter space where their network behavior is effectively the same as ordinary cosmic strings.