Extragalactic Point Source Search in Five-year WMAP 41, 61 and 94 GHz Maps

TL;DR

This paper reports a new search for extragalactic point sources in five-year WMAP data using a CMB-free technique, identifying 381 sources including 89 new ones, with high reliability demonstrated through simulations.

Contribution

The study introduces a novel CMB-free method for detecting extragalactic point sources in WMAP data, improving source identification accuracy and revealing new sources.

Findings

Identified 381 sources at >5 sigma, including 89 new sources.

Achieved 96.3% identification rate for detected sources.

Validated detection method with simulations showing consistent results.

Abstract

We present the results of an extragalactic point source search using the five-year WMAP 41, 61 and 94 GHz (Q-, V- and W-band) temperature maps. This work is an extension of our point source search in the WMAP maps applying a CMB-free technique. An internal linear combination (ILC) map has been formed from the three-band maps, with the weights chosen to remove the CMB anisotropy signal as well as to favor a selection of flat-spectrum sources. We find 381 sources at the > 5 sigma level outside the WMAP point source detection mask in the ILC map, among which 89 are "new" (i.e., not present in the WMAP catalog). Source fluxes have been calculated and corrected for the Eddington bias. We have solidly identified 367 (96.3%) of our sources. The 1 sigma positional uncertainty is estimated to be 2'. The 14 unidentified sources could be either extended radio structure or obscured by Galactic emission. We have also applied the same detection process on simulated maps and found 364+/-21 detections on average. The recovered source distribution N(>S) agrees well with the simulation input, which proves the reliability of this method.