The Sunyaev Zel'dovich contribution in CMB power spectra analysis : from contaminant to usefull signal

Abstract

The Sunyaev Zel'dovich effect is expected to be one of the major contaminants at arcminutes scales in CMB analysis. I will present a method we developed at IAS to quantify the biases on parameter determination when any additive signal is not taken into account in the analysis. I will then present an application of this method in order to quantify the biases induced on cosmological parameter estimation when the SZ residuals are not properly taken into account in the analysis of the CMB. The important biases that would result from such a treatment encouraged us to developed a joint analysis of the CMB plus SZ signal that consists in determining the cosmological parameters fitting both signals. I will compare various methods to carry out such an analysis and will emphasize that only the coherent method that takes into account the dependency of the SZ spectrum with all the cosmological parameters allows an unbiased determination of the parameters. I will conclude by discussing the improvement on parameters error bars du to the extra information included in the SZ power spectrum and by pointing out the difficulties that our incomplete understanding of the intra cluster gas physics can set.