We present a method, based on the correlation function of excursion sets above a given threshold, to test the Gaussianity of the cosmic microwave background (CMB) temperature fluctuations in the sky. In particular, this method can be applied to discriminate between standard inflationary scenarios and those producing non-Gaussianity such as topological defects. We have obtained the normalized correlation of excursion sets, including different levels of noise, for two-point probability density functions constructed from the Gaussian, Xn2 and Laplace one-point probability density functions in two different ways. Considering subdegree angular scales, we find that this method can distinguish between different distributions even if the corresponding marginal probability density functions and/or the radiation power spectra are the same.

EMG, JL Sand RBB acknowledge financial support from the Spanish DGES, project PB95-1132-C0202, CICYT, project ESP96-2798-E and from Comision Mixta Caja Cantabria-Universidad de Cantabria. RBBacknowledges a Spanish M.E.C. PhD scholarship.

Peer reviewed