| Abstract |
We present a semi-analytic model for the formation and evolution of high-redshift galaxies. We investigate cosmic star formation rates and the reionization history, using our galaxy model in which we include a novel implementation of dust size evolution and resulting molecular hydrogen (H_2) formation on dust grains in the early universe. We show cosmic star formation efficiency of our model is low, because the H_2 formation rate on dust grains is suppressed by the dust destruction by reverse shocks in supernova remnants. Our results show need of additional reioniation sources or top-heavy IMF in z > 6 for the cosmological reionization. We conclude that not only the amount but also the size distribution of dust strongly affects the cosmic star formation efficiency and the IMF transition from Pop III to Pop II. |
