Hellings-Downs 1983: angular-correlation in pulsar-timing residuals for stochastic-GW background; quadrupolar pattern with ~1/3 amplitude at 90 deg, peaks at 0+180 deg; signature observed by NANOGrav 15-yr 2023 (3+ sigma).
Hellings-Downs 1983: angular-correlation in pulsar-timing residuals for stochastic-GW background; quadrupolar pattern with ~1/3 amplitude at 90 deg, peaks at 0+180 deg; signature observed by NANOGrav 15-yr 2023 (3+ sigma).