Testing Gaussianity on Archeops Data

Abstract

A Gaussianity analysis using a goodness-of-fit test and the Minkowski functionals on the sphere has been performed to study the measured Archeops Cosmic Microwave Background (CMB) temperature anisotropy data for a 143 GHz Archeops bolometer. We consider large angular scales, greater than 1.8 degrees, and a large fraction of the North Galactic hemisphere, around 16%, with a galactic latitude b > 15 degrees. The considered goodness-of-fit test, first proposed by Rayner & Best (1989), has been applied to the data after a signal-to-noise decomposition. The three Minkowski functionals on the sphere have been used to construct a chi-square statistic using different thresholds. The first method has been calibrated using simulations of Archeops data containing the CMB signal and instrumental noise in order to check its asymptotic convergence. Two kind of maps produced with two different map-making techniques (coaddition and Mirage) have been analysed. Archeops maps for both Mirage and coaddition map-making, have been found to be compatible with Gaussianity. From these results we can exclude a dust and atmospheric contamination larger than 7.8% (90% CL). Also the non-linear coupling parameter f_{nl} can be constrained to be -800 < f_{nl} < 1100 at the 95% CL and on angular scales of 1.8 degrees. For comparison, the same method has been applied to data from the NASA WMAP satellite in the same region of sky. The 1-year and 3-year releases have been used. Results are compatible with those obtained with Archeops, implying in particular an upper limit for f_{nl} on degree angular scales.