The NANOGrav 11 Year Data Set: Pulsar-Timing Constraints on the Stochastic Gravitational-Wave Background
Z. Arzoumanian et al 2018 ApJ 859 47
11 years of data from NanoGRAV place constraints on a population of inspiraling supermassive black hole binaries, a network of decaying cosmic strings, and a primordial gravitational-wave background.