The metal enrichment of elliptical galaxies in hierarchical galaxy formation models
The metal enrichment of elliptical galaxies in hierarchical galaxy formation models
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DOI：
10.1111/j.1745-3933.2005.00078.x
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发表时间：
2005-04
影响因子：
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通讯作者：
M. Nagashima;C. Lacey;T. Okamoto;C. Baugh;C. Frenk;S. Cole
中科院分区：
文献类型：
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作者：
M. Nagashima;C. Lacey;T. Okamoto;C. Baugh;C. Frenk;S. Cole
在星系形成的层次模型框架下，我们研究了椭圆星系的金属富集。我们使用的半分析模型已被Nagashima等人用于研究团内介质（ICM）的金属富集，包括气体和金属流入和流出星系的影响，以及Ia型和II型超新星引起的金属富集过程。我们采用太阳邻域初始质量函数（IMF）的星星形成光盘，但考虑模型中，恒星爆发有一个太阳邻域IMF或头重脚轻的IMF。我们发现，只有在采用顶重IMF时，椭圆星系中的α元素丰度才与观测值一致。这一结果与我们以前对ICM金属富集的研究一致。本文还讨论了α元素与铁的丰度比随速度弥散度和金属丰度的变化。我们发现，具有头重脚轻IMF的模型与在典型L* 椭圆星系中观察到的α/Fe比相匹配，但没有一个模型再现了观察到的α/Fe随速度弥散的增加。
We investigate the metal enrichment of elliptical galaxies in the framework of hierarchical models of galaxy formation. The semi-analytical model we use, which has been used to study the metal enrichment of the intracluster medium (ICM) by Nagashima et al., includes the effects of flows of gas and metals both into and out of galaxies and the processes of metal enrichment due to both type Ia and type II supernovae. We adopt a solar neighbourhood initial mass function (IMF) for star formation in discs, but consider models in which starbursts have either a solar neighbourhood IMF or a top-heavy IMF. We find that the α-element abundance in ellipticals is consistent with observed values only if the top-heavy IMF is used. This result is consistent with our previous study on the metal enrichment of the ICM. We also discuss the abundance ratio of α elements to iron as a function of velocity dispersion and metallicity. We find that models with a top-heavy IMF match the α/Fe ratios observed in typical L* ellipticals, but none of the models reproduces the observed increase of α/Fe with velocity dispersion.