Galaxy Evolution and Environment

星系的形成和演化与其所处的环境和大尺度结构密切相关。 星系群和星系团提供了一个独特的实验室来研究一系列环境（直到宇宙中最密集的环境）对星系演化和恒星形成历史的影响。星团演化的研究，包括星系族群、星团形态、合并、星团质量函数和巨型中央星系（称为最亮星团星系，或 BGC）的形成，为许多与星系形成和演化、大尺度结构的增长和宇宙学直接相关的问题提供了信息。 ***我的建议将基于三项大型星团调查，旨在优化红移 (z) 大于 1 的星团研究（或者，当宇宙小于当前年龄的一半时）。已经完成数据采集和缩减的两项巡天是： SpARCS（斯皮策红序星团巡天改编）巡天，利用斯皮策太空望远镜的红外成像与地面望远镜的光学成像相结合，生成 z>1 时超过 200 个星团的目录； GCLASS（双子星团天体物理科学巡天），从 SpARCS z~1 处获得了 9 个丰富星团中 400 多个星团星系的光谱。第三个是正在进行的GoGreen项目（早期丰富环境中的双子座星系观测），这是双子座天文台批准的大型项目，它将获得21个星系团和星系团中约1000个星系团成员的光谱，z>1。***我提案的一个关键科学目标是使用这些大型光谱和光度目录来探索星系团和星系团中恒星形成抑制的时间尺度。这将通过检查星团不同位置的星系的各种恒星形成指标来完成。另一个主要项目是研究星团和不同星系密度区域中合并星系的频率和类型，使我们能够深入了解合并对恒星形成的诱导和猝灭的贡献。***我还将使用非常广泛的星团和星系目录来研究星系团的形状作为历元的函数，并探讨星系团的形态与星团演化和星团星系种群之间的联系，并将这些结果与模拟进行比较。目标是研究星团形态与星团质量积累和星团恒星含量之间的关系。

The formation and evolution of galaxies is intimately tied to the environment and large scale structure in which they reside. Galaxy groups and clusters provide a unique laboratory to study the effects of a range of environments, up to that of the densest in the universe, on galaxy evolution and the history of star formation. The study of cluster evolution, including the galaxy population, cluster morphology, mergers, cluster mass function and the build-up of the giant central galaxy (called Brightest Cluster Galaxy, or BGC) informs many issues directly related to both galaxy formation and evolution, the growth of large-scale structure, and cosmology. ***My proposal will be based on three large surveys of clusters designed to optimize the study of clusters at redshift (z) greater than 1 (or, when the universe was less than half of its current age). The two surveys already completed their data acquisition and reduction are: the SpARCS (Spitzer Adaptation of the Red-Sequence Cluster Survey) survey, which uses infrared imaging from the Spitzer Space Telescope combined with optical imaging from ground-based telescopes to produce a catalog of over 200 clusters at z>1; and GCLASS (Gemini Cluster Astrophysical Science Survey), which obtained spectra for over 400 cluster galaxies in 9 of the riches clusters from SpARCS at z~1. The third is the on-going GoGreen Project (Gemini Observations of Galaxies in Early Rich Environments), an approved large program at the Gemini Observatory, which will obtain spectra for ~1000 cluster members in 21 galaxy clusters and groups at z>1.***One key scientific goal of my proposal is to use these large spectroscopic and photometric catalogs to explore the time scale of the suppression of star formation in galaxies in-falling into groups and clusters. This will be done by examining various star-formation indicators for galaxies in different locations of the clusters. Another main project is to investigate the frequency and types of merging galaxies in clusters and different galaxy density regions, allowing us to gain insights into the contribution of mergers to both inducing and the quenching of star formation.***I will also use the very extensive cluster and galaxy catalogs to investigate the shape of galaxy clusters as a function of epoch and probe the connections between the morphology of galaxy clusters to cluster evolution and the cluster galaxy population, comparing these results with simulations. The goal is to investigate how cluster morphology correlates with the mass build-up of clusters and stellar contents of clusters.