LARGE-SCALE MODES OF CLEANED THREE-YEAR WMAP CMB MAP

Abstract

We have produced a cleaned map of the WMAP three-year data using an improved version of an internal linear combination (ILC) method to subtract the Galactic foreground emission. We divide the whole sky into hundreds of pixel groups with similar foreground spectral indices over a range of WMAP frequencies, apply the ILC for each group, and obtain a CMB map with foreground emission effectively reduced. With the resulting foreground-reduced ILC map, we have investigated the known anomalies in CMB maps at large scales, and confirmed that the quadrupole power is low and the quadrupole and the octopole are strongly aligned and are planar. Although our estimates are consistent with the previous measurements, ILC simulation implies that the observed low quadrupole power and the alignment between the quadrupole and the octopole are marginally statistically significant, and the observed planarity is not statistically significant.