Nonlinear evolution of density perturbations

Abstract

From the epoch of recombination (z~10³) till today, the typical density contrasts have grown by a factor of about 10⁶ in a Friedmann universe with Ω= 1. However, during the same epoch the typical gravitational potential has grown only by a factor of order unity. This fact can be exploited to provide a new, powerful, approximation scheme to study the formation of nonlinear structures in the universe by evolving the initial distribution of matter using a gravitational potential frozen in time. We carry out this scheme for several standard models and discuss the results.