Correlations of Richness and Global Properties in Galaxy Clusters
Correlations of Richness and Global Properties in Galaxy Clusters
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星系团中丰富度与全局属性的相关性
DOI：
10.1086/345929
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发表时间：
2002
期刊：
影响因子：
--
通讯作者：
E. Ellingson
中科院分区：
文献类型：
--
作者：
H. Yee;H. Yee;E. Ellingson;E. Ellingson
丰富度是星系团的一个关键特征。我们利用星系团中心相关幅值Bgc测量了加拿大观测宇宙团红移巡天网络中星系团的光学丰富度。研究表明，利用光度表测量的Bgc值与红移表测量的Bgc值一致，表明即使在~0.6的中等红移下，仅用光度数据也可以可靠地测量丰富度。我们建立了光学丰富度与星系团其他重要属性（如速度色散、质量、半径、x射线温度和光度）之间的相关性。我们发现这些量与丰富度的标度关系与假设ρ ~ r-1.8在0.5 h Mpc时的简单质量密度曲线所得到的结果完全一致。Bgc与速度色散和x射线温度之间的良好相关性允许人们使用丰富度，这是一个容易测量的数量，仅使用相对较浅的光学成像数据，作为中度红移的这些数量的预测因子。Bgc参数可用于估计星团的速度色散，精度约为15%(~±100 km s-1)， x射线温度约为20%。丰富度与集群的特征半径和质量之间也有类似的相关性，但散点较大。我们比较了Bgc、TX和LX作为动态质量预测器的相对优点，发现它们是可比较的，提供的估计精度约为30%。我们还对低红移Abell集群样本的丰富度和速度色散、TX和LX之间的相关性进行了类似的分析，并发现了一致的结果，但散点较大，这可能是数据库不太均匀或样本依赖效应的结果。
Richness is a key defining characteristic of a galaxy cluster. We measure the optical richness of galaxy clusters from the Canadian Network for Observational Cosmology Cluster Redshift Survey using the galaxy cluster center correlation amplitude Bgc. We show that the Bgc values measured using photometric catalogs are consistent with those derived from redshift catalogs, indicating that richness can be measured reliably from photometric data alone, even at moderate redshifts of ~0.6. We establish the correlations between optical richness and other important attributes of a galaxy cluster, such as velocity dispersion, mass, radius, and X-ray temperature and luminosity. We find that the scaling relations of these quantities with richness are entirely consistent with those derived by assuming a simple mass density profile at 0.5 h Mpc of ρ ~ r-1.8. The excellent correlations between Bgc and velocity dispersion and X-ray temperature allow one to use richness, an easily measurable quantity using relatively shallow optical imaging data alone, as a predictor of these quantities at moderate redshifts. The Bgc parameter can be used to estimate the velocity dispersion of a cluster to a precision of approximately 15% (~±100 km s-1) and X-ray temperature to about 20%. Similar correlations, but with larger scatter, are also obtained between richness and the characteristic radius and mass of the clusters. We compare the relative merits of Bgc, TX, and LX as predictors of the dynamical mass and find that they are comparable, providing estimates at an accuracy of ~30%. We also perform similar analyses of correlations between richness and velocity dispersion, TX, and LX with a sample of low-redshift Abell clusters and find consistent results, but with larger scatter, which may be the result of a less homogeneous database or sample-dependent effects.