Extragalactic point-source search in WMAP 61 and 94 GHz data

We report the results of an extragalactic point-source search using the 61 and 94 GHz (V-and W-band) temperature maps from the Wilkinson Microwave Anisotropy Probe (WMAP). Applying a method that cancels the "noise'' due to the CMB anisotropy signal, we find in the vertical bar b vertical bar > 10 degrees region 31 sources in the first-year maps and 64 sources in the three-year co-added maps at a 5 sigma level. The 1 sigma position uncertainties are 1.6' and 1.4', respectively. The increased detections and improved positional accuracy are expected from the higher signal-to-noise ratio of the WMAP three-year data. All sources detected in the first-year maps are repeatedly detected in the three-year maps, which is a strong indication of the consistency of this method. Of all the sources, 97% are identified with either the WMAP three-year source catalog or plausible extrapolations of lower frequency data, which indicates that our method is also reliable. The two unidentified sources have been recently confirmed to be false detections, using the WMAP five-year data. We derive the source count distribution at the WMAP V band by combining our verified detections with sources from the WMAP three-year catalog. If we assume that the effect of source clustering is negligible, the contribution to the power spectrum from faint sources below 0.75 Jy is estimated to bed (2.4 +/- 0.8) x 10(-3) mu K-2 sr for the V band, which implies a source correction amplitude of A 0.012 +/- 0.004 mu K-2 sr.