Cosmic microwave background and foregrounds in Wilkinson Microwave Anisotropy Probe first-year data

We perform a blind multicomponent analysis of the Wilkinson Microwave Anisotropy Probe (WMAP) 1-yr foreground-cleaned maps using Spectral Matching Independent Component Analysis (SMICA). We provide a new estimate of the cosmic microwave background (CMB) power spectrum as well as the amplitude of the CMB anisotropies across frequency channels. We show that the CMB anisotropies are compatible with temperature fluctuations as expected from the standard paradigm. The analysis also allows us to identify and separate a weak residual Galactic emission, present significantly in the Q band outside of the Kp2(1) mask limits, and mainly concentrated at low Galactic latitudes. We produce a map of this residual component by Wiener filtering using estimated parameters. The level of contamination of CMB data by this component is compatible with the WMAP-team estimation of foreground residual contamination. In addition, the multicomponent analysis allows us to estimate jointly the power spectrum of unresolved point-source emission.