A SIMPLE TEST FOR NON-GAUSSIANITY IN COSMIC MICROWAVE BACKGROUND-RADIATION MEASUREMENTS

We propose a set of statistics for detecting non-Gaussianity in one-di mensional cosmic microwave background radiation (CMBR) anisotropy data sets. These statistics are both simple and, according to calculations over a space of linear combinations of three-point functions, nearly optimal at detecting certain types of non-Gaussian features. We use th is statistic to analyze the anisotropy detected by the UCSB SP91 exper iment. According to this statistic the mean of the four frequency chan nels is significantly non-Gaussian. If this signal represents primordi al CMBR fluctuations, it would be highly unlikely in a Gaussian theory with a small coherence angle, such as ''standard'' (n = 1, Omega(b) = 0.05, h = 0.5, Lambda = 0) inflation. We cannot tell whether the obse rved non-Gaussian signal is cosmological in origin, but if we assume i t due instead to foreground emission, and remove the points responsibl e for the non-Gaussian behavior, the rms of the remaining fluctuations is improbably low for the ''standard'' inflation theory. Further data are clearly needed before any definitive conclusions may be drawn. We also generalize the ideas behind this statistic to non-Gaussian featu res that might be detected in other experimental schemes.