Small scale contributions to the cosmic microwave background: a coherent analysis

¹ LATT, 14 avenue Édouard Belin, 31400 Toulouse, France e-mail: douspis@ast.obs-mip.fr
² Institut d'Astrophysique Spatiale (IAS), Université Paris-Sud 11, CNRS (UMR 8617), Bâtiment 121, 91405 Orsay, France

Received: 26 January 2006
Accepted: 22 May 2006

Abstract

We re-analyse Cosmic Microwave Background data from experiments probing both large and small scales. We assume that measured anisotropies are due not only to primary fluctuations but also, especially at small scales, to secondary effects (namely the Sunyaev-Zel'dovich effect) and possible point source contamination. We first consider primary and secondary anisotropies. For the first time in such analyses, the cosmological dependence of secondary fluctuations is fully taken into account. We show that in that case a higher value of the normalisation is preferred, as found by previous studies, but also higher values of the optical depth τ and power spectrum index n_s are needed. In the second part, we include possible contaminations from unresolved and unremoved point sources. We discuss the effects on the cosmological parameters. We further obtain the best combination of relative contributions of the three kinds of sources to the measured microwave power on small scales at each frequency. Our method allows us to simultaneously obtain cosmological parameters and explain the so-called small scale power excess in a consistent way.