Feedback from the First Stars: Chemical Abundances in the First Billion Years after the Big Bang

要了解宇宙中第一批恒星是如何形成的，以及它们的形成和生命周期如何影响宇宙中第一批星系的形成，还有大量的工作要做。了解这些基本细节将为了解我们银河系和许多其他星系的形成和生命历史提供重要线索。该项目旨在追踪星系际介质（IGM）中重化学元素在非常高红移时的时间历史。因为大多数研究人员认为，来自超新星和/或活动星系核（AGN）的加热在星系组装中起着至关重要的作用，首席研究员（PI）选择研究重元素，这是这种加热“反馈”的副产品。PI将解决以下具体的科学问题：(1)随着再电离时代的临近，C - IV丰度是否会下降？(2)在红移6左右重元素体系的电离结构是否有变化？(3)在红移6处，QSO视线吸收特性的巨大差异反映了宇宙的变化还是随机早期恒星形成的特征？(4)星系晕在早期以冷重子（见Mg II）填充的机制是什么？这个项目更广泛的影响包括重要的教育组成部分。一名研究生将获得三年的资助，PI将与他所在的机构密切合作，指导本科生进行研究和天文观测活动。在与来自物理科学领域代表性不足的群体的学生合作方面，PI也有着出色的记录。

A great deal of work remains to understand how the first stars in the Universe formed and how their formation and life cycles affected the formation of the first galaxies in the Universe. Understanding these essential details will provide important clues to understanding the formation and life history of our own Galaxy and many others. This project aims to track the time history of heavy chemical elements in the intergalactic medium (IGM) at very high redshift. Because most researchers believe that heating from supernovae and/or active galactic nuclei (AGN) played a vital role in galaxy assembly, the principal investigator (PI) has chosen to study the heavy elements, which are a byproduct of this heating "feedback." The PI will address the following specific scientific questions: (1) Is there a decline in the C IV abundance as the epoch of reionization is approached? (2) Is there a change in the ionization structure of heavy element systems at redshift around 6? (3) Do the large differences in absorption properties between QSO sightlines at redshift 6 reflect cosmic variance or a signature of stochastic early star formation? (4) What mechanism populates galaxy haloes with cold baryons (seen in Mg II) at early times?The broader impacts of this project include important educational components. A graduate student will be supported for the three years of this grant, and the PI works closely with his institution to mentor undergraduates in research and astronomical observing activities. The PI also has an excellent track record in working with students from groups underrepresented in the physical sciences.