A needlet internal linear combination analysis of WMAP 7-year data: estimation of CMB temperature map and power spectrum

The WMAP 7-year temperature maps have been re-analized to extract a CMB map and CMB power spectrum with reduced contamination by astrophysical foregrounds and noise. The method used is based on linear combinations of WMAP data and foreground templates, implemented on a decomposition of the observations onto a needlet frame. We obtain a clean CMB map with low contamination from foregrounds and noise, as well as a new estimate of the CMB temperature power spectrum. The latter is essentially compatible with the power spectrum published by the WMAP collaboration, although it is slightly but systematically lower on large scales. The exact origin of this discrepancy is not clear.