Non--Gaussian Effects in the Cosmic Microwave Background from Inflation

Abstract

The presence of non--Gaussian features in the Cosmic Microwave Background (CMB) radiation maps represents one of the most long--awaited clues in the search for the actual structure of the primordial radiation, still needing confirmation. These features could shed some light on the non trivial task of distinguishing the real source of the primeval perturbations leading to large scale structure. One of the simplest non--Gaussian signals to search is the (dimensionless) skewness ${\cal S}$. Explicit computations for ${\cal S}$ are presented in the frame of physically motivated inflationary models (natural, intermediate and polynomial potential inflation) in the hope of finding values in agreement with estimated quantities from large angle scale (e.g., {\em COBE} DMR) maps. In all the cases considered the non--Gaussian effects turn out to lie below the level of theoretical uncertainty (cosmic variance). The possibility of unveiling the signal for ${\cal S}$ with multiple--field models is also discussed.