Title: Optical Redshift and Richness Estimates for Galaxy Clusters Selected with the Sunyaev-Zel'dovich Effect from 2008 South Pole Telescope Observations Show Chinese title

Title: 基于2008年南极望远镜SZ效应巡测选出的星系团的光学红移和丰度估计

Abstract: We present redshifts and optical richness properties of 21 galaxy clusters uniformly selected by their Sunyaev-Zel'dovich signature. These clusters, plus an additional, unconfirmed candidate, were detected in a 178 square-degree area surveyed by the South Pole Telescope in 2008. Using griz imaging from the Blanco Cosmology Survey and from pointed Magellan telescope observations, as well as spectroscopy using Magellan facilities, we confirm the existence of clustered red-sequence galaxies, report red-sequence photometric redshifts, present spectroscopic redshifts for a subsample, and derive R_200 radii and M_200 masses from optical richness. The clusters span redshifts from 0.15 to greater than 1, with a median redshift of 0.74; three clusters are estimated to be at z > 1. Redshifts inferred from mean red-sequence colors exhibit 2% RMS scatter in sigma_z/(1+z) with respect to the spectroscopic subsample for z < 1. We show that M_200 cluster masses derived from optical richness correlate with masses derived from South Pole Telescope data and agree with previously derived scaling relations to within the uncertainties. Optical and infrared imaging is an efficient means of cluster identification and redshift estimation in large Sunyaev-Zel'dovich surveys, and exploiting the same data for richness measurements, as we have done, will be useful for constraining cluster masses and radii for large samples in cosmological analysis. Show Chinese abstract

Abstract: 我们展示了21个星系团的红移和光学丰富度性质，这些星系团是根据其太阳泽尔多维奇信号均匀选择的。 这些星系团加上一个额外的、未确认的候选者，是在2008年由南极望远镜在178平方度的区域内探测到的。 利用Blanco宇宙学调查的griz成像数据以及指向性麦哲伦望远镜观测数据，并结合使用麦哲伦设施的光谱学，我们确认了聚集的红序列星系的存在，报告了红序列的测光红移，展示了子样本的光谱红移，并从光学丰富度推导出R_200半径和M_200质量。 这些星系团的红移范围从0.15到大于1，其中位数红移为0.74；估计有三个星系团位于z > 1。 由平均红序列颜色推断的红移，在z < 1的情况下，在sigma_z/(1+z)中相对于光谱子样本表现出2%的RMS散射。 我们表明，从光学丰富度推导的M_200星系团质量与来自南极望远镜数据的推导的质量相关，并且与先前得出的比例关系在不确定性范围内一致。 光学和红外成像是大规模太阳泽尔多维奇巡天中识别星系团和估算红移的有效方法，利用相同数据进行丰富度测量，正如我们所做的那样，对于在宇宙学分析中的大样本限制星系团质量和半径将是很有用的。