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

研究了包括核心塌缩超新星(CCSNe)和对不稳定超新星(PISNE)在内的三族超新星喷出物中尘埃的形成。对于喷出物中的元素组成，考虑了两种极端情况：氦核内的非混合情况和均匀混合情况。CCSNe和PISNE的计算结果如下：(1)在未混合的喷射物中，多种颗粒凝聚在一起，反映了喷射物中形成位置的元素组成的差异；否则，只有硅酸盐和氧化物颗粒在均匀混合的喷射物中凝聚。(2)除未混合的硅酸盐、氧化镁、硅和FeS，以及两种情况下的Al_2O_3外，所有颗粒的粒度分布函数均近似为对数正态分布。所有颗粒的粒度分布函数可用幂函数近似，其指数分别为-3.5和-2.5，交叉点的半径范围为0.004.1~0.1μm，具体取决于前驱粒子的质量。(3)随着星体质量的增加，尘埃粒子所占质量的比例增加：CCSNe星云的星体质量为2%~5%，PISNE星云的星体质量为15%~30%，星际激波的初始质量函数、恒星形成率和尘埃破坏效率为参数，根据计算的超新星尘埃产生量，估算了早期宇宙中尘埃粒子的数量。计算结果表明，粉尘量对除尘效率非常敏感。

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.