Joint X-ray/Sunyaev-Zel'dovich Analysis of the Intra-Cluster Medium
  We present results from a joint X-ray/Sunyaev-Zel'dovich modeling of the
intra-cluster gas using XMM-Newton and APEX-SZ imaging data. The goal is to
study the physical properties of the intra-cluster gas with a non-parametric
de-projection method that is, aside from the assumption of spherical symmetry,
free from modeling bias. We demonstrate a decrease of gas temperature in the
cluster outskirts, and also measure the gas entropy profile, both of which are
obtained for the first time independently of X-ray spectroscopy, using
Sunyaev-Zel'dovich and X-ray imaging data. The contribution of the APEX-SZ
systematic uncertainties in measuring the gas temperature at large radii is
shown to be small compared to the XMM-Newton and Chandra systematic
spectroscopic errors.
