Extragalactic Point Source Search in WMAP 61 and 94 GHz Data

TL;DR

This study identifies extragalactic point sources in WMAP 61 and 94 GHz data, improving detection reliability and positional accuracy, and estimates their contribution to the CMB power spectrum.

Contribution

Introduces a noise-canceling method for point source detection in WMAP data, revealing new sources and confirming previous detections with higher accuracy.

Findings

Detected 31 sources in first-year maps and 64 in three-year maps.

Identified 21 new sources not in previous catalogs.

Estimated the contribution of faint sources to the power spectrum.

Abstract

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 $|b| > 10\degr$ 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' each. The increased detections and improved positional accuracy are expected from the higher signal-to-noise ratio of WMAP three-year data. All sources detected in the first-year maps are repeatedly detected in the three-year maps, which is a strong proof of the consistency and reliability of this method. Among all the detections, 21 are new, i.e. not in the WMAP three-year point source catalog. We associate all but two of them with known objects. The two unidentified sources are likely to be variable or extended as observations through VLA, CARMA and ATCA all show non-detection at the nominal locations. We derive the source count distribution at WMAP V-band by combining our verified detections with sources from the WMAP three-year catalog. Assuming the effect of source clustering is negligible, the contribution to the power spectrum from faint sources below 0.75 Jy is estimated to be $(2.4\pm0.8) \times 10^{-3} \mu K^2$ sr for V-band, which implies a source correction amplitude $A = 0.012\pm0.004 \mu K^2$ sr.