PROBING BARYONIC PROCESSES AND GASTROPHYSICS IN THE FORMATION OF THE MILKY WAY DWARF SATELLITES. I. METALLICITY DISTRIBUTION PROPERTIES
PROBING BARYONIC PROCESSES AND GASTROPHYSICS IN THE FORMATION OF THE MILKY WAY DWARF SATELLITES. I. METALLICITY DISTRIBUTION PROPERTIES
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DOI：
10.1088/0004-637x/791/1/8
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发表时间：
2014-06
期刊：
影响因子：
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通讯作者：
Jun-Peng Hou;Qingjuan Yu;Youjun Lu
中科院分区：
文献类型：
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作者：
Jun-Peng Hou;Qingjuan Yu;Youjun Lu
银河系矮卫星星系是目前宇宙中发现的最小的星系，是研究早期宇宙中星系形成过程中各种重子过程的有力工具。在本文中，我们研究了类MW宿主星系周围矮卫星中恒星的化学性质，并探讨了几种重子过程的可能影响，包括超新星（SN）反馈，宇宙的再电离和H2冷却，以及当前和未来的观测如何对这些过程施加一些限制。我们使用半解析模型来生成类MW星系，对于类MW星系，基准模型可以再现MW矮星的光度函数和恒星金属度-恒星质量相关。利用模拟的类MW星系，我们重点研究了它们的矮星的三个金属丰度性质：矮星群体的恒星金属丰度-恒星质量相关，以及单个矮星中恒星金属丰度分布的贫金属和富金属尾。结果表明：（1）恒星金属度-质量关联的斜率对SN反馈强度和再电离时期敏感;（2）富金属尾的延伸主要对SN反馈强度敏感;（3）贫金属尾的延伸主要对再电离时期敏感;（4）三种化学性质对H2冷却过程均不敏感;（5）与目前观测的恒星金属度-质量关系斜率的比较表明，局部宇宙的再电离早于宇宙平均值，局部源对局部区域的再电离可能有重要贡献，且中等到强的SN反馈强度是优选的。未来对恒星金属丰度分布的富金属和贫金属尾部的观测将进一步限制SN反馈和再电离过程。
The Milky Way (MW) dwarf satellites, as the smallest galaxies discovered in the present-day universe, are potentially powerful probes to various baryonic processes in galaxy formation occurring in the early universe. In this paper, we study the chemical properties of the stars in the dwarf satellites around the MW-like host galaxies, and explore the possible effects of several baryonic processes, including supernova (SN) feedback, the reionization of the universe, and H2 cooling, and how current and future observations may put some constraints on these processes. We use a semianalytical model to generate MW-like galaxies, for which a fiducial model can reproduce the luminosity function and the stellar metallicity–stellar mass correlation of the MW dwarfs. Using the simulated MW-like galaxies, we focus on investigating three metallicity properties of their dwarfs: the stellar metallicity–stellar mass correlation of the dwarf population, and the metal-poor and metal-rich tails of the stellar metallicity distribution in individual dwarfs. We find that (1) the slope of the stellar metallicity–stellar mass correlation is sensitive to the SN feedback strength and the reionization epoch; (2) the extension of the metal-rich tails is mainly sensitive to the SN feedback strength; (3) the extension of the metal-poor tails is mainly sensitive to the reionization epoch; (4) none of the three chemical properties are sensitive to the H2 cooling process; and (5) a comparison of our model results with the current observational slope of the stellar metallicity–stellar mass relation suggests that the local universe is reionized earlier than the cosmic average, local sources may have a significant contribution to the reionization in the local region, and an intermediate to strong SN feedback strength is preferred. Future observations of metal-rich and metal-poor tails of stellar metallicity distributions will put further constraints on the SN feedback and the reionization processes.