The Initial Mass Function of the First Stars Inferred from Extremely Metal-poor Stars

Abstract

We compare the elemental abundance patterns of ∼200 extremely metal-poor (EMP; [Fe/H] < 40 M ⊙ , and that more than than half of the stars are best-fitted by the M  = 25 M ⊙ hypernova ( E 51 = 10) models. The results also indicate that the majority of the primordial supernovae have ejected 10 −2 –10 −1 M ⊙ of 56 Ni, leaving behind a compact remnant (either a neutron star or a black hole), with a mass in the range of ∼1.5–5 M ⊙ . These results suggest that the masses of the first stars responsible for the first metal enrichment are predominantly <40 M ⊙ . This implies that the higher-mass first stars were either less abundant, directly collapsed into a black hole without ejecting heavy elements, or a supernova explosion of a higher-mass first star inhibits the formation of the next generation of low-mass stars at [Fe/H] < −3.