Globular Cluster Systems in Extreme Environments: Origins and History

球状星团是由恒星组成的致密、巨大、受引力束缚的星团，在所有大型星系中普遍存在。 它们是最古老的恒星系统之一，形成于宇宙历史的最初几个千兆年，来自早期星系中最密集、最大、最猛烈的恒星形成地点。虽然在今天的宇宙中，GC只占星系中所有恒星质量的百分之一或更少，但它们在追踪恒星和星系演化的巨大过程中发挥着关键作用。 我的研究建议旨在三个这样的路径： (1)在丰富的星系团中，球状星团也存在于星系之间的广阔空间中，这些星系际GC的特征以独特的方式追踪了星系团中星系之间相互作用和相遇的历史。 为了探索这一新领域，我正在领导一个新的观测计划，利用哈勃太空望远镜和斯巴鲁望远镜对英仙座星系团中的星系际GC种群进行全面调查。 (2)最大数量的球状星团存在于最大的星系中：布里渊星系团（BCGs）。 这些星系通过吸收周围较小的卫星星系而成长到今天，但环境对这些巨大星系演化的影响尚未完全了解。 它们的GC种群拥有了解其早期历史的独特线索，因为GC的性质在很大程度上取决于它们起源的星系类型。 作为我正在进行的研究巨型星系中GC系统的计划的一部分，我们将使用我们来自哈勃太空望远镜的新数据，系统地调查BCGs在整个巨大的环境范围内，以了解这些星系的生长速度，以及什么类型的星系有助于它们的生长和组装。 这项工作将填补宇宙中最大星系起源的主要谜团。 (3)一个众所周知的新发现是，一个球状星团内可能有多个恒星种群，它们都具有相同的年龄，但轻元素的比例不同。 目前的观测结果已经很好地证实了这一点，但很难理解它们是如何在如此小的（以银河系的标准）恒星系统中产生的。 目前关于这种效应的起源的想法是有争议的。 基于我们以前的一位博士生的理论工作，我们将追踪星团中最早的大质量恒星对其星星形成气体的内部丰度混合物的影响。 这是一个有前途的和令人兴奋的新途径，了解多个人口的起源，坚实的基础上，我们严格的和定量的理论星星集群的形成。 这项工作有可能塑造社区的研究方向，在早期宇宙中形成巨大的星星集群。

Globular clusters are dense, massive, gravitationally bound clusters of stars that are found universally in all large galaxies. They are among the oldest stellar systems, having formed in the first few Gigayears of the universe's history, out of the densest, most massive, and most violent star-forming sites within early galaxies. Although in the present-day universe GCs make up just a percent or less of all stellar mass in galaxies, they play key roles for tracing a huge range of processes in stellar and galactic evolution. My research proposal aims at three such paths: (1) In rich clusters of galaxies, globular clusters are also found in the vast space between the galaxies, and the characteristics of these intergalactic GCs trace, in a unique way, the histories of interactions and encounters among the galaxies in the cluster. To pursue this new frontier I am leading a new observational program with the Hubble Space Telescope and with the Subaru telescope for a comprehensive survey of the intergalactic GC population in the rich Perseus cluster. (2) The largest numbers of globular clusters are found in the largest galaxies: the Brightest Cluster Galaxies (BCGs). These galaxies grow right up to the present day by absorbing the smaller satellite galaxies around them, but the effects of environment on the evolution of these giant galaxies are not completely understood. Their GC populations hold unique clues to their early history, because GCs have properties that depend strongly on the type of galaxy they originated in. As part of my ongoing program to study the GC systems in giant galaxies, we will use our new data from the Hubble Space Telescope to systematically survey BCGs over their entire huge range of environments to find out how quickly these galaxies grew, and what types of galaxies contributed to their growth and assembly. This work will fill in a major piece of the puzzle for the origin of the largest galaxies in the universe. (3) A well known new discovery is that a single globular cluster may have within it multiple stellar populations that all have the same age but different ratios of the light elements. These are well established by current observations to be present, but it has been difficult to understand how they arose in such small (by galactic standards) stellar systems. Current ideas for the origin of this effect are controversial. Building on theoretical work by one of our former PhD students, we will trace the effects of the earliest massive stars in the cluster on the internal abundance mixture of its star forming gas. This is a promising and exciting new avenue for understanding the origin of multiple populations, based solidly on our rigorous and quantitative theory for star cluster formation. This work has the potential to shape the community's direction of research into the formation of massive star clusters in the early universe.