Globular Cluster Systems in Extreme Environments: Origins and History

极端环境中的球状星团系统：起源和历史

• 批准号: RGPIN-2019-05421
• 负责人: Harris, William
• 金额: $ 2.99万
• 依托单位: McMaster University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2021
• 资助国家: 加拿大
• 起止时间: 2021-01-01 至 2022-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=738268
• 关键词: Globular; Cluster; Systems; Extreme; Environments

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.

球状星团是密度大、质量大、受引力束缚的星团，普遍存在于所有大型星系中。它们是最古老的恒星系统之一，形成于宇宙历史的最初几千年，形成于早期星系中密度最大、质量最大、形成恒星最剧烈的地方。尽管在当今的宇宙中，GCs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一系列过程中发挥着关键作用。我的研究计划主要针对三条路径：(1)在丰富的星系团中，在星系之间的广阔空间中也发现了球状星团，这些星系间gc的特征以独特的方式记录了星系团中星系之间相互作用和相遇的历史。为了探索这个新领域，我正在领导一个新的观测项目，使用哈勃太空望远镜和斯巴鲁望远镜，对丰富的英仙座星系团中的星系间GC群进行全面调查。(2)在最大的星系中发现了数量最多的球状星团：最亮的星团星系（BCGs）。这些星系通过吸收周围较小的卫星星系而成长到今天，但是环境对这些巨大星系演化的影响还没有完全被理解。它们的GC群为它们的早期历史提供了独特的线索，因为GC的特性在很大程度上取决于它们所处星系的类型。作为我正在进行的研究巨型星系中GC系统的项目的一部分，我们将使用哈勃太空望远镜的新数据系统地调查bcg的整个巨大环境范围，以找出这些星系的生长速度，以及哪些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之谜的一个主要部分。(3)一个著名的新发现是，在一个球状星团内可能有多个恒星群，它们的年龄相同，但轻元素的比例不同。目前的观测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（按银河系标准）恒星系统中出现的。目前关于这种效应起源的观点是有争议的。在我们一位前博士生的理论工作基础上，我们将追踪星团中最早的大质量恒星对其恒星形成气体内部丰度混合物的影响。这是一个有希望的和令人兴奋的新途径来理解多种群的起源，坚实地基于我们对星团形成的严格和定量理论。这项工作有可能塑造社区对早期宇宙中大质量星团形成的研究方向。