Cosmic Chemical Evolution Based on the Hierarchical Galaxy Formation Scenario

贫金属恒星的氧/铁丰度比提供了大质量恒星的核合成产额的信息，这些恒星最终会发生II型超新星爆炸。利用银河系化学演化的标准模型，我们重现了太阳邻区丰度数据，并估算了真正的SnII起源的氧和铁的产额。将估计的产额与理论产额进行比较，得出每一代恒星的质量下限和上限与IMF斜率之间的关系。在不考虑这个关系的情况下，我们进一步从太阳近邻的恒星质量与光比出发，导出了低质量直线与IMF斜率之间的关系。这些独立关系明确地确定了m&lt；@d2u@&gt；d2=50(]sy的质量上限。-.国际货币基金组织的斜率指数为1.3-1.6，高于1 M&lt；@D2(]SY.sun.[)@&gt；D2。这一质量上限对应于恒星以黑洞形式结束而不向星际介质喷射经过处理的物质的质量。我们还发现，IMF斜率指数低于0.5M&lt；@D2(]SY.sun.[)@&gt；D2不可能比0.8浅得多。

Oxygen to iron abundance ratios of metal-poor stars provide information on nucleosynthesis yields from massive stars which end in Type II supernova explosions. Using a standard model of chemical evolution of the Galaxy we have reproduced the solar neighborhood abundance data and estimated the oxygen and iron yields of genuine SN II origin. The estimated yields are compared with the theoretical yields to derive the relation between the lower and upper mass limits in each generation of stars and the IMF slope. Independently of this relation, we furthermore derive the relation between the lower mass linit and the IMF slope from the stellar mass to light ratio in the solar neighborhood. These independent relations unambiguously determine the upper mass limit of m<@D2u@>D2=50(]SY.+-。[)10 M<@D2(]SY.sun.[)@>D2 and the IMF slope index of 1.3-1.6 above 1 M<@D2(]SY.sun.[)@>D2. This upper mass limit corresponds to the mass beyond which stars end as black holes without ejecting processed matter into the interstellar medium. we also find that the IMF slope index below 0.5 M<@D2(]SY.sun.[)@>D2 cannot be much shallower than 0.8.