An SZ/X-ray galaxy cluster model and the X-ray follow-up of the Planck   clusters
  Sunyaev-Zel'dovich (SZ) cluster surveys will become an important cosmological tool over next few years, and it will be essential to relate these new surveys to cluster surveys in other wavebands. We present an empirical model of cluster SZ and X-ray observables constructed to address this question and to motivate, dimension and guide X-ray follow-up of SZ surveys. As an example application of the model, we discuss potential XMM-Newton follow-up of Planck clusters. 
A. Chamballu, J. G. Bartlett, J.-B. Melin and M. Arnaud