2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/12960The rate at which galaxy halos form is thought to play a key role in explaining many observable cosmological phenomena such as the initial epoch at which luminous matter forms and the distribution of active galaxies. Here we show how Press-Schechter theory can be used to provide a simple, completely analytic model of the halo formation rate. This model shows good agreement with both Monte-Carlo and N-body simulation results.2 pages, 1 figure, to appear in proceedings of the Xth Recontres de Blois, "The Birth of Galaxies," LaTeX style file includedAstrophysicstext