The Luminosity and Color Dependence of the Galaxy Correlation Function
The Luminosity and Color Dependence of the Galaxy Correlation Function
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DOI：
10.1086/431891
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发表时间：
2004-08
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通讯作者：
I. Zehavi;Z. Zheng;D. Weinberg;J. Frieman;A. Berlind;M. Blanton;R. Scoccimarro;R. Sheth;M. St
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作者：
I. Zehavi;Z. Zheng;D. Weinberg;J. Frieman;A. Berlind;M. Blanton;R. Scoccimarro;R. Sheth;M. St
我们在斯隆数字巡天中研究了星系两点相关函数的光度和颜色相关性，从2500°2以上的大约20万个星系的样本开始。我们将分析集中在特定光度范围的体积受限的子样本上，对于这些子样本，我们测量投影的关联函数wp(Rp)，它与真实空间的关联函数ξ(R)直接相关。从MR≈-17.5到MR≈-22.5，wp(Rp)的幅度随着光度的增加而不断增加，最快的增加出现在特征光度L*(MR≈-20.5)以上。在尺度上，0.1h~(-1)MPC-22可以用幂函数ξ(R)=(r/R0)-γ来近似，γ≈为1.8，R0(L*)≈为5.0h~(-1)MPC。最亮的亚样-23<；mr<；-22的ξ(R)要陡峭得多。当我们按颜色划分样本时，越红的星系在所有光度下都表现出更高的幅度和更陡峭的关联函数。蓝星系的相关幅度随光度的增加而不断增大，但红星系的光度依赖关系不那么规律性，亮红星系在大尺度上表现出最强的星系团，暗红星系在小尺度上表现出最强的星团。我们用假设协调宇宙学参数的晕占据分布(HOD)模型解释了这些结果。对于大多数样品，带两个可调参数的HOD模型对wp(Rp)数据的拟合要好于幂定律，它将Rp~1-3h-1Mpc处的拐点解释为ξ(R)的单晕和双晕区域之间的转变。对于一个拥有比L更亮的中央星系的晕，隐含的最小质量稳步增长，Mmin∝L在低亮度下，对L的依赖更大*。在所有光度下，一个晕平均比L亮一个卫星星系的质量是M1≈23 Mmin(L)。这些结果暗示了一个条件光度函数(在固定晕质量下)，其中中心星系位于卫星群的谢克特函数外推法之上。HOD模型很好地解释了wp(Rp)的颜色相关性以及红星系和蓝星系之间的相互关联。对于有MR<；-21的星系，Mmin上方的晕有蓝色的中心星系，而质量较大的晕有红色的中央星系和主要的红色卫星群。蓝色中心星系的比例随着光度和宿主晕质量的降低而稳步增加。暗红色星系的强烈成团源于这样一个事实，即几乎所有这些星系都是大质量晕中的卫星系统。HOD拟合结果与星系形成的数值模型和半解析模型的预测在定性上是一致的。
We study the luminosity and color dependence of the galaxy two-point correlation function in the Sloan Digital Sky Survey, starting from a sample of ~200,000 galaxies over 2500 deg2. We concentrate our analysis on volume-limited subsamples of specified luminosity ranges, for which we measure the projected correlation function wp(rp), which is directly related to the real-space correlation function ξ(r). The amplitude of wp(rp) rises continuously with luminosity from Mr ≈ -17.5 to Mr ≈ -22.5, with the most rapid increase occurring above the characteristic luminosity L* (Mr ≈ -20.5). Over the scales 0.1 h-1 Mpc -22 can be approximated, imperfectly, by power-law three-dimensional correlation functions ξ(r) = (r/r0)-γ with γ ≈ 1.8 and r0(L*) ≈ 5.0 h-1 Mpc. The brightest subsample, -23 < Mr < -22, has a significantly steeper ξ(r). When we divide samples by color, redder galaxies exhibit a higher amplitude and steeper correlation function at all luminosities. The correlation amplitude of blue galaxies increases continuously with luminosity, but the luminosity dependence for red galaxies is less regular, with bright red galaxies exhibiting the strongest clustering at large scales and faint red galaxies exhibiting the strongest clustering at small scales. We interpret these results using halo occupation distribution (HOD) models assuming concordance cosmological parameters. For most samples, an HOD model with two adjustable parameters fits the wp(rp) data better than a power law, explaining inflections at rp ~ 1-3 h-1 Mpc as the transition between the one-halo and two-halo regimes of ξ(r). The implied minimum mass for a halo hosting a central galaxy more luminous than L grows steadily, with Mmin ∝ L at low luminosities and a steeper dependence above L*. The mass at which a halo has, on average, one satellite galaxy brighter than L is M1 ≈ 23Mmin(L), at all luminosities. These results imply a conditional luminosity function (at fixed halo mass) in which central galaxies lie far above a Schechter function extrapolation of the satellite population. The HOD model fits nicely explain the color dependence of wp(rp) and the cross correlation between red and blue galaxies. For galaxies with Mr < -21, halos slightly above Mmin have blue central galaxies, while more massive halos have red central galaxies and predominantly red satellite populations. The fraction of blue central galaxies increases steadily with decreasing luminosity and host halo mass. The strong clustering of faint red galaxies follows from the fact that nearly all of them are satellite systems in high-mass halos. The HOD fitting results are in good qualitative agreement with the predictions of numerical and semianalytic models of galaxy formation.