SIMBAD references

We calculate nucleosynthesis in core collapse explosions of massive Population III stars and compare the results with abundances of metal-poor halo stars to constrain the parameters of Population III supernovae. We focus on iron peak elements, and, in particular, we try to reproduce the large [Zn/Fe] observed in extremely metal-poor stars. The interesting trends of the observed ratios [Zn, Co, Mn, Cr, V/Fe] can be related to the variation of the relative mass of the complete and incomplete Si-burning regions in supernova ejecta. We find that [Zn/Fe] is larger for deeper mass cuts, smaller neutron excess, and larger explosion energies. The large [Zn/Fe] and [O/Fe] observed in the very metal-poor halo stars suggest deep mixing of complete Si-burning material and a significant amount of fallback in Type II supernovae. Furthermore, large explosion energies (E₅₁≳2 for M∼13 M_☉ and E₅₁≳20 for M≳20 M_☉) are required to reproduce [Zn/Fe]∼0.5. The observed trends of the abundance ratios among the iron peak elements are better explained with this high-energy (``hypernova'') model than with the simple ``deep'' mass cut effect because the overabundance of Ni can be avoided in the hypernova models. We also present the yields of pair instability supernova explosions of M≃130-300 M_☉ stars and discuss that the abundance features of very metal-poor stars cannot be explained by pair instability supernovae.