Cosmic Superstrings Revisited in Light of NANOGrav 15-Year Data

Abstract

We analyze cosmic superstring models in light of NANOGrav 15-year pulsar timing data. A good fit is found for a string tension $G\hat{I}¼\sim 10^{-12}-10^{-11}$ and a string intercommutation probability $p\sim 10^{-3}-10^{-1}$. Extrapolation to higher frequencies assuming standard Big Bang cosmology is compatible at the 68\% CL with the current LIGO/Virgo/KAGRA upper limit on a stochastic gravitational wave background in the 10 to 100 Hz range. The superstring interpretation of the NANOGrav data would be robustly testable by future experiments even in modified cosmological scenarios.

7 pages 4 figures. Typos fixed and new references added