http://arxiv.org/abs/1806.06979
A low-frequency gravitational-wave background (GWB) from the cosmic merger history of supermassive black holes is expected to be detected the next few years by pulsar timing arrays. A GWB induces distinctive correlations in the pulsar residuals (the expected arrival time of the pulse minus its actual arrival time). Previously, simplifying assumptions were made in order to write an analytic expression for this correlation function, called the Hellings and Downs curve for an isotropic GWB, which depends on the angular separation of the pulsar pairs, the gravitational-wave frequency considered, and the distance to the pulsars. Here we prove analytically and generally that the Hellings and Downs curve can be recovered without making the usual assumption that the pulsars are all at the same distance from Earth. In fact, we show that the Hellings and Downs curve can be recovered for pulsars even at formally infinite distances from Earth.
C. Mingarelli and A. Mingarelli
Wed, 20 Jun 18
45/58
Comments: 10 pages, 2 figures