Contribution of Very Massive Population III Stars to the Chemical Enrichment

摘要

The first chemical enrichment has been made by supernovae (SNe) of metal-free Population (Pop) III stars. The first generation stars predicted to be as massive as >300 M_☉. Although such very massive stars (VMSs) had been considered to directly collapse to black holes, the VMSs are suggested to be able to explode as gamma-ray bursts (GRBs). In order to clarify whether such VMSs can contribute to the chemical enrichment, we present explosive nucleosynthesis in VMS explosions and compare the abundance patterns of their yields with those of the extremely metal-poor (EMP) stars. It is shown that the yields of VMS explosions with explosion energy of 6.3 × 10~(54) erg cannot reproduce [C/Fe], [Mg/Fe], and [Zn/Fe] simultaneously. This implies that the VMSs are likely not to dominantly contribute to the chemical enrichment in the early universe.