Skewness as a test of non-Gaussian primordial density fluctuations

We investigate the evolution of the skewness of the distribution of densityfluctuations in CDM models with both Gaussian and non--Gaussian initialfluctuations. We show that the method proposed by Coles \& Frenk (1991), whichuses the skewness of galaxy counts to test the hypothesis of Gaussianprimordial density fluctuations, is a potentially powerful probe of initialconditions. As expected, the mass distribution in models with initiallynon--Gaussian fluctuations shows systematic departures from the Gaussianbehaviour on intermediate to large scales. We investigate the effect ofpeculiar velocity distortions and normalisation upon the relationship betweenskewness and variance. These effects are generally small for the models weconsider. Comparing our results to the QDOT measurements of the skewness, wefind that our initially positive--skew models are clearly excluded by thisanalysis, but the available data do not rule out the negative--skew models.Comment: 1+12 pages (in Latex), 3 figures available upon request, DAPD-20