UvA

We will discuss implications of correlations between the X-ray and optical properties of globular clusters in early-type galaxies. The probability that a globular cluster contains an X-ray binary depends primarily on the cluster's mass and metallicity, with at most weak dependences on its age. The X-ray properties of the globular cluster X-ray sources also show a dependence on metallicity, with the metal poor clusters hosting sources with systematically harder X-ray spectra than the metal rich clusters.