Cosmic String Interpretation of NANOGrav Pulsar Timing Data

Pulsar timing data used to provide upper limits on a possible stochastic gravitational wave background (SGWB). However, the NANOGrav Collaboration has recently reported strong evidence for a stochastic common-spectrum process, which we interpret as a SGWB in the framework of cosmic strings. The possible NANOGrav signal would correspond to a string tension G mu is an element of (4 x 10(-11),10(-10)) at the 68% confidence level, with a different frequency dependence from supennassive black hole mergers. The SGWB produced by cosmic strings with such values of Gu would be beyond the reach of LIGO, but could be measured by other planned and proposed detectors such as SKA, LISA, TianQin, AION-1 km, AEDGE, Einstein Telescope, and Cosmic Explorer.

Automated summary

Pulsar timing data was used to set upper limits on a stochastic gravitational wave background, but recent findings from the NANOGrav Collaboration suggest a stochastic common-spectrum process, potentially related to cosmic strings. The SGWB signal identified by NANOGrav falls within a specific range of string tension values and could be measured by various detectors beyond the capabilities of LIGO.