RUI: Galaxy Construction and Destruction

星系的起源是现代天体物理学中最突出的问题之一。星系是如何形成的，又是什么时候形成的？随着时间的推移，这些星系是如何进化的？环境如何影响星系的性质？揭开星系形成秘密的一种方法是研究它们的球状星系团。球状星团是由多达100万颗恒星组成的致密聚集体，存在于大多数星系的光晕中。它们被认为是宇宙中最古老的恒星群之一，很可能早于其母星系的形成。因此，这些来自早期宇宙的化石遗骸可能为星系的诞生提供重要线索。一旦星系形成，它们就会受到碰撞、合并，以及与其他星系相互作用造成的部分甚至全部毁灭。例如，大星系可能会通过吞噬较小的星系同伴来生长，这是一种银河系自相残杀的行为。此外，碰撞期间从星系中撕裂出来的物质最终可能会被并入其他新的或现有的星系中，这是一种宇宙尺度上的循环。因此，星系的诞生和灭亡似乎是交织在一起的。在过去的几年里，天文学家们一直在探索一些原创的研究路线，包括观测和理论研究，以了解星系的构建和毁灭。这项研究项目的目标是在以往成功的基础上继续和扩大。这个研究项目的具体目标是：分析大样本星系中球状星系团的金属丰度分布，以便对这些星系以前的合并历史施加定量约束。使用最近采用的建模技术，现在可以确定一个星系今天的光度中有多少是通过合并和/或吸收潮汐剥离物质从其他星系继承而来的。使用球状星团作为诊断，现在可以更准确地确定这种合并是如何发生的。寻找预期的星际球状星团群体，这些星系团不属于任何特定的星系，而是在处女座和彗星等丰富的星系团的核心自由漫游。这种星际球状星团的群体肯定存在，这是银河系潮汐相互作用的结果，这种相互作用会移走恒星和球状星团，并将它们扩散到整个星际空间。该项目的目标是利用主要地面天文台的数据和即将进行的哈勃太空望远镜观测来寻找这一预期的星际球状星系团。目前正在进行的对尾巴星系团的多色成像调查将继续进行，这是有史以来最雄心勃勃的星系团调查。目标之一是提供对彗星团星系光度函数的明确测量，并寻找因穿过彗星核心而受到潮汐干扰的星系的微弱残骸。这项调查将提供一个非常丰富的数据库，可供多年使用。这项研究计划将涉及不同大学的许多合作者，并将包括夏威夷大学希洛分校的本科生天文学专业的学生。该项目由天文科学部资助。

AST-0071149WESTThe genesis of galaxies is one of the great outstanding problems in modern astrophysics. How and when did galaxies form? How have the galaxies evolved over time? How does environment influence galaxy properties? One way to unravel the secrets of galaxy formation is by studying their globular cluster systems. Globular clusters are dense aggregates of up to a million stars that are found in the halos of most galaxies. They are believed to be among the oldest stellar ensembles in the universe, most likely predating the formation of their parent galaxies. As such, these fossil remains from the early universe may provide important clues about the birth of galaxies. Once galaxies have formed, they are subject to collisions, mergers, and partial or even total destruction from interactions with other galaxies. For example, large galaxies may grow by devouring smaller galaxy companions in an act of galactic cannibalism. Furthermore, material torn from galaxies during collisions may eventually be incorporated into other new or existing galaxies, a sort of recycling on cosmic scales. The birth and death of galaxies thus appear to be interwoven. Over the past few years, astronomers have been pursuing a number of original lines of research, both observational and theoretical, to understand the construction and destruction of galaxies. The goals of this research project are to continue and expand upon previous successes. Specific goals of this research project are:To analyze the globular cluster metallicity distributions in a large sample of galaxies in order to place quantitative constraints on the previous merger histories of these galaxies. Using a recently adapted modeling technique, it is now possible to determine what fraction of the present-day luminosity of a galaxy has been inherited from other galaxies via mergers and/or accretion of tidally stripped material. It is now possible to determine more precisely how of this sort of merging has occurred, using globular clusters as a diagnostic.To search for an expected population of intergalactic globular clusters which do not belong to any particular galaxy, but rather roam freely throughout the cores of rich galaxy clusters such as Virgo and Coma. Such a population of intergalactic globular clusters must surely exist, a consequence of galaxy tidal interactions, which remove stars and globular clusters and spread them throughout intergalactic space. This goal of the project is to search for this expected population of intergalactic globular clusters using data from major ground-based observatories and upcoming Hubble Space Telescope observations.An ongoing wide-field, multi-color imaging survey of the Coma cluster of galaxies, the most ambitious cluster survey ever undertaken, will be continued. Among the goals are to provide a definitive measurement of the luminosity function of the Coma cluster galaxies, and to search for the faint remains of galaxies, which have been tidally disrupted by their passage through Coma's core. This survey will provide an extremely rich database that can be used for many years.The research program will involve a number of collaborators at different universities and will include undergraduate astronomy students at the University of Hawaii at Hilo.This project is funded by the Division of Astronomical Sciences.***