Mapping the large-angle deviation from Gaussianity in simulated CMB maps

Centro Brasileiro de Pesquisas F´isicas, Rua Dr. Xavier Sigaud 150, 22290-180 Rio de Janeiro – RJ, Brazil(Dated: September 29, 2011)The detection of the type and level of primordial non-Gaussianity in the CMB data is essentialto probe the physics of the early universe. Since one does not expect that a single statisticalestimator can be sensitive to all possible forms of non-Gaussianity which may be present in thedata, it is important to employ different statistical indicators to study non-Gaussianity of CMB. Inrecent works we have proposed two new large-angle non-Gaussianity indicators based on skewnessand kurtosis of patches of CMB sky-sphere, and used them to find out significant deviation fromGaussianity in frequency bands and foreground-reduced CMB maps. Simulated CMB maps withassigned type and amplitude of primordial non-Gaussianity are important tools to determine thestrength, sensitivity and limitations of non-Gaussian estimators. Here we investigate whether andto what extent our non-Gaussian indicators have sensitivity to detect non-Gaussianity of local type,particularly with amplitude within the seven-year WMAP bounds. We make a systematic study byemploying our statistical tools to generate maps of skewness and kurtosis from several thousandsof simulated maps equipped with non-Gaussianity of local type of various amplitudes. We showthat our indicators can be used to detect large-angle local-type non-Gaussianity only for relativelylarge values of the non-linear parameter f