Deriving the Hubble constant using Planck and XMM-Newton observations of
  galaxy clusters
  The possibility of determining the value of the Hubble constant using
observations of galaxy clusters in X-ray and microwave wavelengths through the
Sunyaev Zel\'dovich (SZ) effect has long been known. Previous measurements have
been plagued by relatively large errors in the observational data and severe
biases induced, for example, by cluster triaxiality and clumpiness. The advent
of \textit{Planck} allows us to map the Compton parameter y, that is, the
amplitude of the SZ effect, with unprecedented accuracy at intermediate
cluster-centric radii, which in turn allows performing a detailed spatially
resolved comparison with X-ray measurements. Given such higher quality
observational data, we developed a Bayesian approach that combines informed
priors on the physics of the intracluster medium obtained from hydrodynamical
simulations of massive clusters with measurement uncertainties.
  We apply our method to a sample of 61 galaxy clusters with redshifts up to z
< 0.5 observed with Planck and XMM-Newton observations and find H_0=67 \pm 3 km
s^{-1} Mpc^{-1}.
