Hierarchical Object Formation in the Peculiar Velocity Field

Using the initial peculiar-velocity field, we analytically study the hierarchical formation of gravitationally bound objects. The field is smoothed over a scale that corresponds to the mass of a given class of objects. Through the Zel’dovich approximation, the smoothed field determines how the objects cluster together to form a new class of more massive objects. The standard cosmological parameters lead to the evolution of primordial clouds with ≤ 10M⊙ → galaxies with 10M⊙ → clusters of galaxies with 10M⊙ → superclusters of galaxies with 10M⊙. The epochs obtained for the formation of these classes of objects are consistent with observations. Subject headings: cosmology: theory — galaxies: formation — large scale structure of universe