Cosmic Star Formation History from Local Observations and an Outline for Galaxy Formation and Evolution

Abstract

The goal of this investigation is to reconstruct the cosmic star formation rate density history from local observations and in doing so to gain insight into how galaxies might have formed and evolved. A new chemical evolution model is described which accounts for the formation of globular clusters as well as the accompanying field stars. When this model is used in conjunction with the observed age metallicity relations for the clusters and with input which allows for the formation of the nearly universally observed bimodal distribution of globular clusters, star formation rates are obtained. By confining attention to a representative volume of the local universe, these rates allow a successful reconstruction of the Madau plot while complementary results similtaneously satisfy many local cosmological constraints. A physical framework for galaxy formation is presented which incorporates the results from this chemical evolution model and assumes an anisotropic collapse. In addition to providing the `classical' halo, bulge and disk components, the model also predicts a new stellar halo component with peak [Fe/H] ~ -0.8 and disk-like angular momentum and allows for the formation of a thick disk as outlined by the group of metal rich globular clusters. Milky Way counterparts of the latter two components are identified.