arXiv 0710.37802007-10-22astro-ph

SDSS星系团和星系群的星系含量

The Galaxy Content of SDSS Clusters and Groups

Sarah M. Hansen, Erin S. Sheldon, Risa H. Wechsler, Benjamin P. Koester

备注：: 22 pages, 14 figures, submitted to ApJ
发表信息：: Astrophys.J.699:1333-1353,2009
DOI：: 10.1088/0004-637X/699/2/1333

摘要：

斯隆数字巡天的成像数据被用来描述MaxBCG算法探测到的星系群和星系团的特征。本文研究了在红移0.1 < z < 0.3的范围内，亮星系团的光度、伴星系光度和伴星系色的分布与星系团性质的关系。数据集的大小允许我们在许多箱中测量星系团的丰富度，半径和红移。我们发现，在r_200范围内，质量大于3e ~（13）h ~（-1）M_sun的星团，红、蓝卫星的光度函数对丰富度的依赖性都很弱。我们进一步发现，当亮度大于^{0.25}M_i - 5log（h）<-19时，卫星光度函数的形状不依赖于星团中心距离。然而，微弱的红色和蓝色星系的混合发生了巨大的变化。卫星的红色部分取决于星系团的中心距离、星系光度和星系团质量，并且在红移0.28和0.2之间增加约5%，与丰富度无关。我们发现BCG光度与星系团的丰富度密切相关，标度为L_{BCG} ~ M_{200} ^{0.3}，并且在固定的丰富度下具有高斯分布，对于大质量星系团，sigma_{log L} sigma_{log L} ~ 0.17。BCG光度与总星系团光度和特征卫星光度的比值与星系团丰富度密切相关：在较丰富的系统中，BCG贡献的总光的比例较小，但与典型卫星相比更亮。这项研究证明了互相关技术的力量，用于测量星系人口在纯粹的光度数据。

英文摘要：

Imaging data from the Sloan Digital Sky Survey are used to characterize the population of galaxies in groups and clusters detected with the MaxBCG algorithm. We investigate the dependence of Brightest Cluster Galaxy (BCG) luminosity, and the distributions of satellite galaxy luminosity and satellite color, on cluster properties over the redshift range 0.1 < z < 0.3. The size of the dataset allows us to make measurements in many bins of cluster richness, radius and redshift. We find that, within r_200 of clusters with mass above 3e13 h-1 M_sun, the luminosity function of both red and blue satellites is only weakly dependent on richness. We further find that the shape of the satellite luminosity function does not depend on cluster-centric distance for magnitudes brighter than ^{0.25}M_i - 5log(h) < -19. However, the mix of faint red and blue galaxies changes dramatically. The satellite red fraction is dependent on cluster-centric distance, galaxy luminosity and cluster mass, and also increases by ~5% between redshifts 0.28 and 0.2, independent of richness. We find that BCG luminosity is tightly correlated with cluster richness, scaling as L_{BCG} ~ M_{200}^{0.3}, and has a Gaussian distribution at fixed richness, with sigma_{log L} ~ 0.17 for massive clusters. The ratios of BCG luminosity to total cluster luminosity and characteristic satellite luminosity scale strongly with cluster richness: in richer systems, BCGs contribute a smaller fraction of the total light, but are brighter compared to typical satellites. This study demonstrates the power of cross-correlation techniques for measuring galaxy populations in purely photometric data.

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