The important role of evolution in the Planck Y_SZ-mass calibration

INAF-Osservatorio Astronomico di Brera, via Brera 28, 20121 Milano, Italy
e-mail: stefano.andreon@brera.inaf.it

Received: 12 June 2014
Accepted: 29 September 2014

Abstract

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 ± 0.4}(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 ± 0.07, which is shallower by 4.8σ 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.