Looking for non-Gaussianity in the COBE-DMR data with spherical wavelets
R.B.BARREIRO (a), M.P.HOBSON (a) , A.N.LASENBY (a), A.J.BANDAY (b), K.M. G\'ORSKI (c) and G. HINSHAW (d)
(a) Astrophysics Group, Cavendish Laboratory, Madingley Road, Cambridge CB3 0HE, UK
(b) Max-Planck Institut fuer Astrophysik (MPA), Karl-Schwarzschild Str.1, D-85740, Garching, Germany (c) European Southern Observatory (ESO), Karl-Schwarzschild Str.2, D-85740, Garching, Germany (d) NASA/GSFC, Greenbelt, MD 20771, USA


Abstract:
We present an analysis of the Gaussianity of the 4-year COBE-DMR data (in HEALPix pixelisation) based on spherical wavelets. The skewness, kurtosis and scale-scale correlation spectra are computed from the detail wavelet coefficients at each scale. The sensitivity of the method to the orientation of the data is also taken into account. We find a single detection of non-Gaussianity at the $>99\%$ confidence level in one of our statistics. We use Monte-Carlo simulations to assess the statistical significance of this detection and find that the probability of obtaining such a detection by chance for an underlying Gaussian field is as high as $0.69$. Therefore, our analysis does not show evidence of non-Gaussianity in the COBE-DMR data.