Searching for nonGaussianity in the WMAP data.pdf

Searching for non-Gaussianity in the WMAP data A. Bernui1, ∗ and M.J. Rebou¸cas2, † 1Instituto Nacional de Pesquisas Espaciais – Divis˜ao de Astrof´ısica Av. dos Astronautas 1758 12227-010 S˜ao Jos´e dos Campos – SP, Brazil 2 Centro Brasileiro de Pesquisas F´ısicas Rua Dr. Xavier Sigaud 150 22290-180 Rio de Janeiro – RJ, Brazil (Dated: June 23, 2008) Some analyses of recent cosmic microwave background (CMB) data have provided hints that there are deviations from Gaussianity in the WMAP CMB temperature fluctuations. Given the far 8 reaching consequences of such a non-gaussianity for our understanding of the physics of the early 0 universe, it is important to employ alternative indicators in order to determine whether the reported 0 non-Gaussianity is of cosmological origin, and/or extract further information that may be helpful 2 for identifying its causes. We propose two new non-Gaussianity indicators, based on skewness and kurtosis of large-angle patches of CMB maps, which provide a measure of departure from Gaussianity n u on large angular scales. A distinctive feature of these indicators it that they provide sky maps of J non-Gaussianity of the C