Non-Gaussianity in the HILC foreground-reduced three-year WMAP CMB map

TL;DR

This paper investigates the non-Gaussian features in the three-year WMAP CMB maps using new indicators, finding significant deviations from Gaussianity in full-sky maps that diminish when applying the KQ75 mask, aiding understanding of early universe physics.

Contribution

The study introduces and applies two new large-angle non-Gaussianity indicators to analyze three-year WMAP data, extending previous five-year analyses and providing insights into the Gaussianity of foreground-reduced CMB maps.

Findings

Full-sky foreground-reduced maps show significant non-Gaussianity.

Applying the KQ75 mask reduces non-Gaussianity to consistent levels.

Results support the importance of masking in CMB Gaussianity analysis.

Abstract

A detection or nondetection of primordial non-Gaussianity in the CMB data is essential not only to test alternative models of the physics of the early universe but also to discriminate among classes of inflationary models. Given this far reaching consequences of such a non-Gaussianity detection for our understanding of the physics of the early universe, it is important to employ alternative indicators in order to have further information about the Gaussianity features of CMB that may be helpful for identifying their origins. In this way, a considerable effort has recently gone into the design of non-Gaussianity indicators, and in their application in the search for deviation from Gaussianity in the CMB data. Recently we have proposed two new large-angle non-Gaussianity indicators which provide measures of the departure from Gaussianity on large angular scales. We have used these indicators to carry out analyses of Gaussianity of the single frequency bands and of the available foreground-reduced {\it five-year} maps with and without the KQ75 mask. Here we extend and complement these studies by performing a new analysis of deviation from Gaussianity of the {\it three-year} harmonic ILC (HILC) foreground-reduced full-sky and KQ75 masked maps obtained from WMAP data. We show that this full-sky foreground-reduced maps presents a significant deviation from Gaussianity, which is brought down to a level of consistency with Gaussianity when the KQ75 mask is employed.