标题： 层次宇宙结构模型中的化学演化 I：早期恒星初始质量函数的限制 显示英文标题

标题： Chemical Evolution in Hierarchical Models Of Cosmic Structure I: Constraints on the Early Stellar Initial Mass Function

摘要： 我提出了一种新的银河系化学演化模型，该模型以星系形成的等级理论为基础，并由银河系的晕族合并历史表达出来。 这个模型能够精确再现今天位于银河晕中第二星族恒星的“金属丰度分布函数”（MDF）。 观测到的MDF以及晕族中真第三星族恒星的明显缺失强烈表明存在一个临界金属丰度，\( Z_\{\text\{crit\}\} \sim 10^\{-4\} Z_\{\odot\} \)，低于此值低质量恒星形成受到抑制，甚至可能是不可能的。 从晕族MDF的观测限制、银河晕恒星的相对金属丰度以及重新电离IGM所需的电离光子预算得出的约束条件共同表明，恒星初始质量函数（IMF）在经历核心坍缩超新星的大质量恒星范围内达到峰值，平均质量 \( <M> = 8 - 42 M_\{\odot\} \)。 这个质量范围与原始恒星形成模型预测的质量范围相似，这些模型考虑了形成反馈。 该模型还暗示，[Fe/H] <~ -3以下的贫金属晕族恒星只有1到10颗无金属恒星作为它们的超新星前身星，因此这些晕族恒星中的相对丰度表现出第一代超新星固有产出的初始质量函数加权平均值。 本文是连接早期恒星形成的高红移原位指示器与第一代恒星的低红移古老遗迹这一长期项目的第一个部分。 显示英文摘要

摘要： I present a new Galactic chemical evolution model motivated by and grounded in the hierarchical theory of galaxy formation, as expressed by a halo merger history of the Galaxy. This model accurately reproduces the "metallicity distribution function" (MDF) for Population II stars residing today in the Galactic halo. The observed MDF and the apparent absence of true Population III stars from the halo strongly imply that there is some critical metallicity, Z_crit <~ 10^-4 Z_sun, below which low-mass star formation is inhibited, and perhaps impossible. The observed constraints from the halo MDF, relative metal abundances from Galactic halo stars, and the ionizing photon budget needed to reionize the IGM together imply a stellar IMF that is peaked in the range of massive stars that experience core-collapse supernovae, with mean mass <M> = 8 - 42 Msun. This mass range is similar to the masses predicted by models of primordial star formation that account for formation feedback. The model also implies that metal-poor halo stars below [Fe/H] <~ -3 had only 1 - 10 metal-free stars as their supernova precursors, such that the relative abundances in these halo stars exhibit IMF-weighted averages over the intrinsic yields of the first supernovae. This paper is the first part of a long term project to connect the high-redshift in situ indicators of early star formation with the low-z, old remnants of the first stars.