Point-source Power in 3 Year Wilkinson Microwave Anisotropy Probe Data

Using a set of multifrequency cross spectra computed from the 3 year WMAP sky maps, we fit for the unresolved point-source contribution. For a white-noise power spectrum, we find a Q-band amplitude of A p 0.011 mK sr (antenna temperature), significantly smaller than the value of mK sr used to correct 0.001 0.017 0.002 the spectra in the WMAP release. Modifying the point-source correction in this way largely resolves the discrepancy that Eriksen et al. found between the WMAP Vand W-band power spectra. Correcting the co-added WMAP spectrum for both the low-l power excess due to a suboptimal likelihood approximation—also reported by Eriksen et al.—and the high-l power deficit due to oversubtracted point sources—presented in this Letter—we find that the net effect in terms of cosmological parameters is an ∼0.7 j shift in to larger values. For the combination ns of WMAP, BOOMERANG, and ACBAR data, we find , lowering the significance of n p 0.969 0.016 s from ∼2.7 j to ∼2.0 j. n ( 1 s Subject headings: cosmic microwave background — cosmology: observations — methods: numerical