Collaborative Research: Optical Confirmation, Redshifts, and Richness for Galaxy Clusters Discovered with the South Pole Telescope

该项目以光学（可见光）观测为中心，使用大型地面望远镜，旨在最大限度地利用南极望远镜（SPT）的科学回报。SPT是一项由美国国家科学基金会资助的实验，位于阿蒙森-斯科特南极站，由一个直径10米的毫米波射电望远镜组成，旨在测量多个波长下宇宙背景辐射（CBR）亮度的细微波动。作为其调查工作的一部分，SPT正在制作一份可能的星系团列表，这些星系团内部的热等离子体对CBR的影响可以探测到。这种光谱扭曲的大小，被称为Sunyaev-Zel'dovich （SZ）效应，与距离无关，为宇宙中星系团的清查提供了机会，相对不受影响其他类型观测的强烈距离偏差的影响。在这个项目中，来自史密森天体物理天文台和哈佛大学的合作小组将对候选SPT星团进行光学后续观测，以确认星团的存在，获得它们的红移，并确定成员星系。该团队将利用现有大型望远镜上的一系列现有仪器，包括PISCO，这是一种由美国国家科学基金会支持为6.5米麦哲伦望远镜开发的多带通成像相机。这项工作的主要结果将是一个前所未有的，容量有限的大约600个星系团的目录。光谱学和光谱观测的完整目录将通过一个使用完善的数据库架构的网络存档发布给天文社区。这些观测的目的是为了进行各种各样的后续调查，包括研究不同环境下的星系演化，努力进一步限制宇宙学参数，以及通过引力透镜测量星系团质量。该项目将支持博士后、研究生和本科生的工作，并将通过首席研究员与重要公共媒体项目的密切参与进行宣传。

This project centers on optical (visible-light) observations using large, ground-based telescopes, designed to maximally exploit the science return from the South Pole Telescope (SPT). The SPT, an NSF-funded experiment at the Amundsen-Scott South Pole Station, consists of a 10-meter diameter, millimeter-wave radio telescope designed to measure the subtle fluctuations in the brightness of the cosmic background radiation (CBR) at multiple wavelengths. As part of its survey operations, the SPT is producing a list of possible galaxy clusters detected by the effect the hot, intra-cluster plasma has on the CBR. The size of this spectral distortion, known as the Sunyaev-Zel'dovich (SZ) effect, is independent of distance, offering the opportunity to inventory galaxy clusters in the universe, relatively free of the strong distance bias that affects other types of observations. In this project the collaborating team (from Smithsonian Astrophysical Observatory and Harvard University) will perform optical follow-up observations of the SPT cluster candidates, to confirm the existence of the clusters, to obtain their redshifts, and to identify the member galaxies. The team will make use of an array of existing instrumentation on the current suite of large telescopes, including PISCO, a multi-bandpass imaging camera developed with NSF support for the 6.5-meter Magellan telescope. The primary result of this work will be an unprecedented, volume-limited catalog of approximately 600 galaxy clusters. The full catalog of photometric and spectroscopic observations will be released to the astronomical community through a web-accessible archive using well-developed database architectures. These observations are intended to enable a wide variety of subsequent inquiries, including studies of galaxy evolution in different environments, efforts to further constrain cosmological parameters, and cluster mass measurements through gravitational lensing. The project will support the work of a postdoctoral fellow, as well as graduate and undergraduate students, and will be publicized through the Principal Investigators' close involvement with significant public-media projects.