Dust in the Early Universe : Dust Formation in the Ejecta of Population III Supernovae

Dust grains play a crucial role on formation and evolution history of stars and galaxies in the early universe. We investigate the formation of dust grains in the ejecta of population III supernovae including pair–instability supernovae which are expected to occur in the early universe, applying a theory of non–steady state nucleation and grain growth. Dust formation calculations are performed for core collapse supernovae with the progenitor mass Mpr ranging from 13 to 30 M⊙ and for pair–instability supernovae with Mpr = 170 and 200 M⊙. In the calculations, the time evolution of gas temperature in the ejecta, which strongly affects the number density and size of newly formed grains, is calculated by solving the radiative transfer equation taking account of the energy deposition of radio active elements. Two extreme cases are considered for the elemental composition in the ejecta; unmixed and uniformly mixed cases within the He–core, and formation of CO and SiO molecules is assumed to be complete. The results of calculations for core collapse supernovae and pair–instability supernovae are summarized as the followings; in the unmixed ejecta, a variety of grain species condense, reflecting the difference of the elemental composition at the formation site in the ejecta, otherwise only oxide grains condense in the uniformly mixed ejecta. The average size of newly formed grains spans the range