I will summarize some key results from a recent paper (Arzoumanian et al 2020 ApJL 905 L34) by the NANOGrav pulsar timing collaboration. Their analysis of 12.5-years of pulsar timing data shows strong evidence of a stochastic process common to all pulsars. However, there is no statistically significant evidence of quadrupolar cross-correlations, which would be needed to claim detection of a gravitational-wave background consistent with the predictions of general relativity. Attributing the signal seen by NANOGrav to an astrophysical gravitational-wave background will require verification on larger data sets and independent analyses.
Orateur: Joseph Romano (NANOGrav collaboration - Texas Tech University)