A needlet ILC analysis of WMAP 7-year data: estimation of CMB temperature map and power spectrum

TL;DR

This paper presents a needlet ILC method to extract a cleaner CMB temperature map and power spectrum from WMAP 7-year data, reducing foreground and noise contamination.

Contribution

The paper introduces a needlet-based ILC approach for improved CMB map and power spectrum estimation from WMAP data.

Findings

Produced a cleaner CMB map with lower foreground contamination.

Estimated a CMB power spectrum slightly lower on large scales.

Results are compatible with WMAP's published spectrum, with some systematic differences.

Abstract

The WMAP 7-year temperature maps have been re-analized to extract a CMB map and CMB power spectrum with reduced contamination by astrophysical foregrounds and noise. The method used is based on linear combinations of WMAP data and foreground templates, implemented on a decomposition of the observations onto a needlet frame. We obtain a clean CMB map with low contamination from foregrounds and noise, as well as a new estimate of the CMB temperature power spectrum. The latter is essentially compatible with the power spectrum published by the WMAP collaboration, although it is slightly but systematically lower on large scales. The exact origin of this discrepancy is not clear.