IS THE DENSITY DISTRIBUTION OF CLUSTERS NON-GAUSSIAN ?

The one-point probability distribution function (pdf) is computed for the $25\hmpc$-smoothed density field of rich clusters of galaxies in the Abell/\aco\ catalogs. The observed pdf is compared to the pdf s drawn similarly from mock catalogs of clusters in cosmological simulations of Gaussian and several non-Gaussian initial conditions. Several statistics allow significant rejection of the non-Gaussian models tested here, and fail to reject the Gaussian model. A comparison with the predictions of second-order perturbation theory and a log-normal model for cdm Gaussian initial conditions yield a linear biasing factor $b_c/b_o \simeq 4$ and $b_c/b_o\simeq 3.7$ for $R\geq 0$ clusters.