Supernova nucleosynthesis, chemical evolution, and cosmic supernova rate
In the chemical evolution of the Galaxy, Type II supernovae (SNe II) have contributed to the early metal enrichment and later Type Ia supernovae (SNe Ia) have contributed to the delayed enrichment of Fe. In principle, hypothetical pre-galactic population III objects could cause the earliest heavy element enrichment. Here we present our two new findings. 1) The peculiar abundance pattern among iron peak elements (Cr, Mn, Co, and Fe) in the very metal poor can be reproduced with SN II nucleosynthesis yields without invoking the contribution from Pop III objects. 2) The observed chemical evolution in the solar neighborhood is well reproduced with the metallicity dependent occurrence of SNe Ia, where SNe Ia do not occur if the iron abundance of the progenitors is as low as [Fe/H] less than or similar to 1. We make the prediction that the cosmic SN Ia rate drops at z similar to 1 - 2 because of the low-iron abundance, which can be observed with the Next Generation Space Telescope.