Implications of Inhomogeneous Metal Mixing for Stellar Archaeology
Implications of Inhomogeneous Metal Mixing for Stellar Archaeology
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DOI：
10.3847/1538-4357/ab960d
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发表时间：
2020-05
期刊：
影响因子：
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通讯作者：
Y. Tarumi;T. Hartwig;M. Magg
中科院分区：
文献类型：
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作者：
Y. Tarumi;T. Hartwig;M. Magg
第一颗超新星使以前的原始气体富含金属，从而形成下一代恒星。基于流体动力学模拟，我们开发了一种新的随机模型来预测第一个星系中恒星形成气体的金属丰度。平均而言，在内部富集的星系中，金属与原始气体充分混合。然而，在外部富集的星系中，金属不容易渗透到致密的气体中，这使得晕内的恒星形成气体和普通气体之间存在显着的金属丰度差异。为了研究这种效应的后果，我们将半解析模型应用于类似银河系的暗物质合并树，并使用一种新颖的现实金属混合配方跟踪从高红移直到今天的恒星化石。我们校准模型以重现低金属丰度下的金属丰度分布函数 (MDF)，并发现斜率从 2 到最佳的原始初始质量函数 (IMF) 可以重现 MDF。我们改进的不均匀混合模型可以对单个迷你晕产生很大影响，但不会显着影响 [Fe/H] ≳ -4 处的建模 MDF 或最拟合的总体 III IMF。
The first supernovae enrich the previously pristine gas with metals, out of which the next generation of stars form. Based on hydrodynamical simulations, we develop a new stochastic model to predict the metallicity of star-forming gas in the first galaxies. On average, in internally enriched galaxies, the metals are well mixed with the pristine gas. However, in externally enriched galaxies, the metals cannot easily penetrate into the dense gas, which yields a significant metallicity difference between the star-forming and average gas inside a halo. To study the consequences of this effect, we apply a semianalytical model to Milky Way–like dark matter merger trees and follow stellar fossils from high redshift until the present day with a novel realistic metal mixing recipe. We calibrate the model to reproduce the metallicity distribution function (MDF) at low metallicities and find that a primordial initial mass function (IMF) with a slope of from 2 to best reproduces the MDF. Our improved model for inhomogeneous mixing can have a large impact for individual minihalos but does not significantly influence the modeled MDF at [Fe/H] ≳ −4 or the best-fitting Population III IMF.