The SZ-observations are effectively probing the pressure of the intracluster medium, which can be combined with X-ray observations providing complementary information on the emission measure and temperature. While in the past the combination of the two sets of observations was used to infer the Hubble constant, it has now become more important to use the well constrained Hubble constant to study the state of the intracluster medium, with one of the most important goals being a precise measurement of the cluster mass, which is important also for the analysis of cluster surveys, since for the cosmological modeling of the results a precise link between the observable parameters and the cluster mass is essential.
The most detailed comparison of an X-ray and SZ map was done by a Japanese group. It shows evidence for a remarkably different distribution, which may be due to density or temperature structure. Such strong differences can affect distance and mass estimates significantly, making detailed cluster maps important supplements to cosmological SZ surveys.
Details on RX J1347:
T = 9.3 keV, Lx=2e46 erg/s, ne(center)=0.09 cm-3, core radius=8", M=1.e15, strong cooling flow, does not follow T-L relation.