A high-significance detection of non-Gaussianity in the WMAP 5-year data using directional spherical wavelets

TL;DR

This paper confirms a significant non-Gaussian signal in the WMAP 5-year data using directional spherical wavelets, consistent with previous findings, and shows it disappears when localized regions are excluded.

Contribution

It applies directional spherical wavelet analysis to the WMAP 5-year data, confirming non-Gaussianity detection with increased significance and consistency with earlier data releases.

Findings

Non-Gaussianity detected at 99% significance in 5-year data

Localized regions contributing to non-Gaussianity are consistent with earlier data

Excluding these regions removes the non-Gaussian signal

Abstract

We repeat the directional spherical real Morlet wavelet analysis, used to detect non-Gaussianity in the Wilkinson Microwave Anisotropy Probe (WMAP) 1-year and 3-year data (McEwen et al. 2005, 2006a), on the WMAP 5-year data. The non-Gaussian signal detected previously is present in the 5-year data at a slightly increased statistical significance of approximately 99%. Localised regions that contribute most strongly to the non-Gaussian signal are found to be very similar to those detected in the previous releases of the WMAP data. When the localised regions detected in the 5-year data are excluded from the analysis the non-Gaussian signal is eliminated.