Cosmic Star Formation: a simple model of the SFRD(z)
  We investigate the evolution of the cosmic star formation rate density (SFRD)
from redshift z=20 to z=0 and compare it with the observational one by Madau
and Dickinson derived from recent compilations of UV and IR data. The
theoretical SFRD(z) and its evolution are obtained using a simple model which
folds together the star formation histories of prototype galaxies designed to
represent real objects of different morphological type along the Hubble
sequence and the hierarchical growing of structures under the action of gravity
from small perturbations to large scale objects in \Lambda-CDM cosmogony, i.e.
the number density of dark matter halos N(M,z). Although the overall model is
very simple and easy to set up, it provides results that well mimic those
obtained from large scale N-body simulations of great complexity. The
simplicity of our approach allows us to test different assumptions for the star
formation law in galaxies, the effects of energy feedback from stars to
interstellar gas and the efficiency of galactic winds, and also the effect of
N(M,z). The result of our analysis is that in the framework of the hierarchical
assembly of galaxies the so-called time-delayed star formation under plain
assumptions mainly for the energy feedback and galactic winds can reproduce the
observational SFRD(z).
