ARIZONA CLUSTER REDSHIFT SURVEY (ACReS)

星系团是揭开星系形成和演化背后的谜团的关键参与者，了解这些谜团对于揭示我们的宇宙是如何进化的，以及了解我们自己的银河系是如何开始的是必要的。长期以来，星系团一直被认为是星系演化的活跃场所，尽管驱动这些转变的物理过程尚未确定。最近的研究表明，即使在距离星系团中心很远的地方，星系群看起来也与野外的不同，这增加了在中间环境中进行星系团星系预处理的可能性。此外，随着样本量的增加，集群合并的普遍性也变得显而易见，这是一个分层世界的自然结果，在这个世界中，集群代表着最大的虚拟对象。这个项目调查了这些事件可能对星系团星系群产生的影响-这些影响目前还没有被很好地理解。结合最近完成的亚利桑那州星系团红移调查(Acres)-一项广泛的、恒星质量精选的广域光谱调查--与现有的多波长数据(从X射线到远红外)相结合，这个项目将研究星系团的等级增长和其重子成分演化之间的联系。该项目的主要目标如下：(1)确定每个星系团的动力学状态，并将其与星系团群体的全球性质相关联；(2)通过识别丝状环境和汇编星系团周围流入星系的独特样本，探测星系团周围的质量分布；(3)将流入星系的性质与其本地环境联系起来，从而确定大范围的星系前处理的地点和必要条件，这个项目的更广泛的影响包括：(1)研究人员将为Acres项目创建一个配套的网站，目标是广泛的受众，突出使用多波长和光谱数据来加深对宇宙的了解。该网站将积极向当地学校教师宣传，供他们在课堂上使用。(2)该项目将在Mt.Lemmon SkyCenter为K-14教师提供了一个机会，让他们与亚利桑那大学的天文学家近距离接触，并将科学发现的兴奋带入亚利桑那州南部的课堂，那里的少数民族学生占学生总数的70%-80%。(3)该项目将建立一个英亩集群数据库，该数据库将在两年期末向社区发布，为今后的集群研究创造遗产。(4)首席研究员将培养本科生和博士后研究员。

Clusters of galaxies are key players in unraveling the mysteries behind galaxy formation and evolution, and understanding such mysteries is necessary to uncover how our Universe evolved and to learn how our own Milky Way Galaxy began. Galaxy clusters have long been considered active sites of galaxy evolution although the physical processes driving these transformations have yet to be established. Recent studies have revealed that, even at large distances from the cluster center, galaxy populations look different from those in the field, and they raise the possibility of cluster galaxy pre-processing in intermediate environments. Furthermore, as sample sizes have increased, the ubiquity of cluster mergers has become apparent, a natural consequence of a hierarchical universe where clusters represent the most massive virialized objects. This project investigates the effects that these events may have on the cluster galaxy population---effects that are currently not well understood.Combining the recently completed Arizona Cluster Redshift Survey (ACReS)---an extensive, stellar-mass selected, wide-field spectroscopic survey---with existing multi-wavelength data (from X-rays to far-infrared), this project will study the connections between a cluster's hierarchical growth and the evolution of its baryonic components. The project's main objectives are the following: (1) to determine each cluster's dynamical state and correlate this with global properties of the cluster galaxy population, (2) to probe the mass distribution surrounding the clusters by identifying filamentary environments and by compiling a unique sample of infalling groups around clusters, and (3) to relate infalling galaxy properties to their local environments, thereby identifying the sites and requisite conditions for galaxy pre-processing in a large, uniform sample of clusters for the first time.The broader impacts of this project include the following: (1) The investigators will create a companion web site for the ACReS project aimed at a wide audience that highlights the use of multi-wavelength and spectroscopic data for a deeper understanding of the Universe. The web site will be aggressively publicized to local school teachers for use in their classrooms. (2) The project will conduct workshops at the Mt. Lemmon SkyCenter for K-14 teachers to bring them into close contact with astronomers at The University of Arizona and bring the excitement of scientific discovery into Southern Arizona classrooms, where ethnic minorities make up to 70-80% of the student population. (3) The project will construct a database for ACReS clusters that will be released to the community at the end of the two year period to create a legacy for future cluster studies. (4) The principal investigator will train undergraduates and a postdoctoral researcher.