Formation of Dust Grains in the Early Universe and its Effects on the Observations.

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Dust formation in the ejecta of population III supernovae including not only core-collapse supernoave (CCSNe) but also pair instability supernovae (PISNE) was investigated. Two extreme cases are considered for the elemental composition in the ejecta ; unmixed and uniformly mixed cases within He-core. The results of the calculations for CCSNe and PISNe are summarized as follows ; (1)A variety of grain species condense in the unmixed ejecta reflecting the diffeience in the elemental composition at the formation site in the ejecta ; otherwise only silicate and oxide grains condense in the uniformly mixed ejecta. (2)The size distribution function of each grain species is approximately log-normal, except for Mg-silicate, MgO,Si,and FeS in the unmixed case, and Al_2O_3 in both cases. The size distribution function summed up over all grain species is approximated by a power-law formula whose index is -3.5 for the larger radius and -2.5 for the smaller one ; the radius at the crossover point ranges from 0.004 to 0.1μm, depending on the progenitor mass. (3)The fraction of mass locked into dust grains increases with increasing the progenitor mass : 2%〜5% of the progenitor mass for CCSNe and 15%〜30% for PISNe whose progenitor mass ranges from 140 to 260 M. Based on the calculated dust yield from supernovae, the amount of dust grains in the early universe is evaluated by applying a closed box model where the initial mass function, star formation rate, and dust destruction efficiency by interstellar shock are taken as the parameters. The result of calculation shows that the amount of dust is very sensitive to the dust destruction efficiency.