The important role of evolution in the Planck Y_{SZ}-mass calibration

In light of the tension between cosmological parameters from Planck cosmic microwave background and galaxy clusters, we revised the Planck analysis of the $Y_{SZ}$-mass calibration to allow evolution to be determined by the data instead of being imposed as an external constraint. Our analysis uses the very same data and Malmquist bias corrections as used by the Planck team in order to emphasize that differences in the results come from differences in the assumptions. The evolution derived from 71 calibrating clusters, with $0.05<z<0.45$, is proportional to $E^{2.5\pm0.4}(z)$, so inconsistent with the self-similar evolution ($E^{2/3}$) assumed by previous analyses. When allowing for evolution, the slope of $Y_{SZ}$-mass relation turns out to be $1.51\pm0.07$, which is shallower by $4.8\sigma$ than the value derived when assuming self-similar evolution, introducing a mass-dependent bias. The non-self-similar evolution of $Y_{SZ}$ has to be accounted for in analyses aimed to establish the biases of Planck masses.