Relative clustering and the joint halo occupation distribution of red sequence and blue-cloud galaxies in COMBO-17
Relative clustering and the joint halo occupation distribution of red sequence and blue-cloud galaxies in COMBO-17
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DOI：
10.1111/j.1365-2966.2009.14973.x
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发表时间：
2008-05
影响因子：
4.8
通讯作者：
P. Simón;M. Hetterscheidt;C. Wolf;K. Meisenheimer;H. Hildebrandt;P. Schneider;M. Schirmer;T. Erben
中科院分区：
文献类型：
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作者：
P. Simón;M. Hetterscheidt;C. Wolf;K. Meisenheimer;H. Hildebrandt;P. Schneider;M. Schirmer;T. Erben
本文研究了红序星系和蓝云星系的相对空间分布，以及它们与COMBO-17探测中暗物质分布的关系。测量了星系团的二阶自相关函数和互相关函数，并用口径统计量表示相对偏差。还估计了星系与利用星系-星系透镜(GGL)的暗物质分布之间的关系。所有的观测数据都进一步用晕模型来解释。为了用晕模型完全解释星系团的互相关函数，我们引入了一个新的参数R，它描述了同一晕内红星系和蓝星系数量之间的统计关联。我们发现，红星系和蓝星系具有明显不同的星系团，没有发现红移的相对星系团的显著演化。有证据表明相对偏差具有尺度依赖性：线性相对偏差因子在空间尺度上分别在约100h-1kpc和7h-1mpc之间略有变化，在b~1.7±0.5和~2.2±0.1之间。星系数密度的线性相关系数从大尺度上接近1的值下降到r~0.6±0.15。这两种偏向趋势，GGL和在一些紧张的情况下，星系数字都可以在光晕模型中得到一致的解释。红色星系通常从≥1012.1±0.2h-1M⊙开始填充光晕，蓝色星系从≥1011.2±0.1h-1M⊙开始填充。对于互相关函数，需要晕圈占用分布(HOD)方差，即使对于相对较小的占用数，该方差也变为泊松。对于我们的样本，这排除了在半分析模型中发现的‘泊松卫星’情景。我们使用贝叶斯证据比较了不同的模型风格，在晕中心有星系和没有星系。结果还没有定论。然而，红色星系必须通过红色中心星系或暗物质上方的浓度参数向晕中心集中。R值取决于中心星系的存在或不存在：如果不允许有中心星系或只允许有红色中心星系，则R一致为零，而如果蓝色和红色星系都可以有中心星系，则需要正相关R=+0.5±0.2。
This paper studies the relative spatial distribution of red-sequence and blue-cloud galaxies, and their relation to the dark matter distribution in the COMBO-17 survey as function of scale down to z ~ 1. We measure the second-order auto- and cross-correlation functions of galaxy clustering and express the relative biasing by using aperture statistics. Also estimated is the relation between the galaxies and the dark matter distribution exploiting galaxy-galaxy lensing (GGL). All observables are further interpreted in terms of a halo model. To fully explain the galaxy clustering cross-correlation function with a halo model, we introduce a new parameter, R, that describes the statistical correlation between numbers of red and blue galaxies within the same halo. We find that red and blue galaxies are clearly differently clustered, a significant evolution of the relative clustering with redshift is not found. There is evidence for a scale-dependence of relative biasing: the linear relative bias factor varies slightly between b ~ 1.7 ± 0.5 and ~2.2 ± 0.1 on spatial scales between roughly 100 h -1 kpc and 7h -1 Mpc, respectively. The linear correlation coefficient of galaxy number densities drops from a value near unity on large scales to r ~ 0.6 ± 0.15. Both biasing trends, the GGL and with some tension the galaxy numbers can be explained consistently within a halo model. Red galaxies typically start to populate haloes with masses starting from ≥10 12.1 ±0.2 h -1 M ⊙ , blue galaxies from ≥10 11.2±0.1 h -1 M ⊙ . For the cross-correlation function, one requires a halo occupation distribution (HOD) variance that becomes Poisson even for relatively small occupancy numbers. This rules out for our samples with high confidence a 'Poisson satellite' scenario, as found in semi-analytical models. We compare different model flavours, with and without galaxies at the halo centres, using Bayesian evidence. The result is inconclusive. However, red galaxies have to be concentrated towards the halo centre either by a red central galaxy or by a concentration parameter above that of dark matter. The value of R depends on the presence or absence of central galaxies: if no central galaxies or only red central galaxies are allowed, R is consistent with zero, whereas a positive correlation R = +0.5 ± 0.2 is needed if both blue and red galaxies can have central galaxies.