|Figure 15: Contours of constant number of X-ray binaries as a function of the “Verbunt parameters”.
Here , , is the average stellar density, is the core radius and
the core velocity dispersion. describes the two-body stellar encounter rate and describes the
rate of encounters between a single binary with the stellar background. The squares represent the
location of various Galactic globular clusters in the plane and the number in parentheses is
the number of X-ray binaries observed in the cluster. Plot reproduced by permission from Banerjee
and Ghosh , copyright by IOP.