Phase analysis of the 1-year WMAP data and its application for the CMB foreground separation

TL;DR

This paper introduces a phase analysis method for separating the cosmic microwave background from foreground signals in WMAP data, utilizing phase correlations across the entire sky without masking or dissection.

Contribution

The novel approach leverages phase correlations of all multipole modes to improve CMB and foreground separation without sky masking, differing from traditional methods.

Findings

The phase analysis reveals significant foreground correlations in WMAP data.

The resulting CMB map's power spectrum aligns with established results.

Derived CMB phases differ slightly from WMAP and TOH maps.

Abstract

We present a new method based on phase analysis for the Galaxy and foreground component separation from the cosmic microwave background (CMB) signal. This method is based on a prevailing assumption that the phases of the underlying CMB signal should have no or little correlation with those of the foregrounds. This method takes into consideration all the phases of each multipole mode (l <= 50, -l <= m <=l) from the whole sky without galactic cut, masks or any dissection of the whole sky into disjoint regions. We use cross correlation of the phases to illustrate that significant correlations of the foregrounds manifest themselves in the phases of the WMAP 5 frequency bands, which are used for separation of the CMB from the signals. Our final phase-cleaned CMB map has the angular power spectrum in agreement with both the WMAP result and that from Tegmark, de Oliveira-Costa and Hamilton (TOH), the phases of our derived CMB signal, however, are slightly different from those of the WMAP Internal Linear Combination map and the TOH map.