Using X-rays to probe the binary content of globular clusters

Globular clusters should harbour a large number of close binaries which are thought to be responsible for delaying the inevitable core collapse of these dense clusters. However, close binaries are hard to identify optically due to the high stellar density. Observing these clusters in X-rays, where in such a domain the compact binaries are bright, diminishes the over-crowding problem. Using the new generation of X-ray observatories, it is possible to identify populations of neutron star low mass X-ray binaries, cataclysmic variables and millisecond pulsars as well as other types of binary systems. We present X-ray and optical evidence for a variety of compact binaries that we have identified in four globular clusters observed by XMM-Newton. We show that through population studies we can begin to understand the formation of individual classes of binaries in globular clusters and hence start to unfold the complex evolutionary paths of these systems.