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

早期宇宙尘埃颗粒的形成及其对观测的影响。

基本信息

批准号：
13640229
负责人：
KOZASA Takashi
金额：
$ 1.15万
依托单位：
HOKKAIDO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2003
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-13640229/
关键词：
dust formation supernoave population III dust early universe 星間物質宇宙論 presolar grains

项目摘要

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.

研究了第三星族超新星（包括核心坍缩超新星（CCSNe）和对不稳定超新星（PISNE））喷出物中尘埃的形成。两个极端的情况下被认为是在喷出物的元素组成，未混合和均匀混合的情况下，在他的核心。CCSNe和PISNe的计算结果概括如下：（1）在未混合的喷出物中凝聚了各种颗粒物质，反映了喷出物中形成位置元素组成的差异;（2）除未混合的Mg-Si、MgO、Si和FeS以及Al_2O_3外，其它颗粒的粒度分布函数均近似于对数正态分布。对所有颗粒种类求和的粒度分布函数近似于幂律公式，其指数对于较大半径为-3.5，对于较小半径为-2.5;交叉点处的半径范围为0.004至0.1μm，取决于原始质量。（3）随着原始质量的增加，被锁入尘埃颗粒的质量分数增加：CCSNe为原始质量的2%~ 5%，PISNe为原始质量的15%~ 30%，原始质量范围为140 ~ 260 M。在计算超新星尘埃产量的基础上，以初始质量函数、星星形成率和星际激波对尘埃的破坏效率为参数，应用封闭箱模型估算了早期宇宙中尘埃颗粒的数量。计算结果表明，粉尘量对除尘效率的影响很敏感。