Using the COBE/DMR data as a test-bed for normality assessments

Abstract

A very important property of a statistical distribution is to know whether it obeys Gaussian statistics or not. On the one hand, it is of paramount importance in the context of CMB anisotropy studies, since deviations from a Gaussian distribution could indicate the presence of uncorrected measurement systematics, of remaining fluctuations contributed by foregrounds, of deviations from the simplest models of inflation or of topological defects. On the other hand, looking for a non-Gaussian signal is a very ill-defined task and performances of various assessment methods may differ widely when applied in different contexts. In previous studies, we introduced a sensitive wavelet-based method which we apply here to the COBE/DMR data set, already extensively studied, using different approaches. This provides an objective way to compare methods. It turns out that our multi-scale wavelet decomposition is a sensitive method. Yet we show that the results are rather sensitive to the choice of both the decomposition scheme and the wavelet basis. We find that the detection of the non-Gaussian signature is ``marginal'' with a probability of at most 99%.

6 pages, 1 figure, accepted for publication in Astronomy & astrophysics

References in corpus (5)

• A Flat Universe from High-Resolution Maps of the Cosmic Microwave Background Radiation
• On the Non-Gaussianity Observed in the COBE-DMR Sky Maps
• New non-Gaussian feature in COBE-DMR Four Year Maps
• Is the cosmic microwave background really non-Gaussian?
• Searching for non-gaussianity: Statistical tests

Cited by in corpus (18)

• Non-Gaussianity from Inflation: Theory and Observations
• First Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Tests of Gaussianity
• Non-Gaussian Signatures in the Temperature Fluctuation Observed by the Wilkinson Microwave Anisotropy Probe
• The performance of spherical wavelets to detect non-Gaussianity in the CMB sky
• Spherical Mexican Hat wavelet: an application to detect non-Gaussianity in the COBE-DMR maps
• A low CMB variance in the WMAP data
• COBE-DMR constraints on the nonlinear coupling parameter: a wavelet based method
• Gaussianity of Degree-Scale Cosmic Microwave Background Anisotropy Observations
• The discriminating power of wavelets to detect non-Gaussianity in the CMB
• Window Function for Non-Circular Beam CMB Anisotropy Experiment
• Long range correlation in cosmic microwave background radiation
• Probing CMB Non-Gaussianity Using Local Curvature
• Characteristic Angular Scales in Cosmic Microwave Background Radiation
• Testing non-Gaussianity in CMB Maps by Morphological Statistic
• Non-Gaussianity due to Possible Residual Foreground Signals in WMAP 1st-year Data Using Spherical Wavelet Approaches
• Finite volume effects for non-Gaussian multi-field inflationary models
• Effect of component separation on the temperature distribution of the CMB
• Cosmic Microwave Background anisotropies: the power spectrum and beyond