不同光度星系大尺度分布的交叉相关分析

在对不同光度星系大尺度分布进行空间两点相关函数分析的基础上,仍以CfA红移巡天资料为样本,对不同光度星系分布进行了交叉相关分析。结果表明,不同光度星系间的交叉相关函数仍可近似地以幂函数表示,说明不同光度星系在空间是一起成团的。但在较小尺度上((?)4—6Mpc),光度较高的星系间相关更强,而在更大一些尺度上光度较高的星系间相关减弱更快,甚至变得比与光度较低星系间的相关更弱。结合前面对自相关函数分析的结果可以看到,统计上看来,星系分布形成群和团。群或团中亮的星系形成更致密的分布而较暗的星系则在这些群和团中分布较弥散。此结果表明星系光度和其环境(密度)有关,从而从观测上为Biased星系形成理论提供了一个可能的证据。

Cross-Correlation Analysis of the Large Scale Distribution of Galaxies With Different Luminosity

Alter making a two-point auto-correlation analysis of galaxies with dillerent luminosities, a cross-correlation analysis of galaxies with different luminosities 'in their large scale distribution has been carried out by using the CfA redshift survey data as a parent sample. The results show that the cross-correlation functions of galaxies with different luminosities can-be approximated by a power function of r, which indicates that the galaxies with different luminosities are mixed in their distribution and clustering. But, on smaller scales (4-6 Mpc) galaxies with a higher luminosity are strongly correlated to each other, and as the scale increasing the correlation between galaxies with a higher luminosity decreases rapidly. Combining with the results obtained by the two-point auto-correlation analysis, we can see that the galaxies with a higher luminosity form more compact and dense distribution in galaxy clusters or galaxy groups, and the less luminous galaxies distribute more diffusely in galaxy clusters. This picture implies that the luminosity of galaxies is correlated to the environment. Thus, results given in this paper might supply an observational evidence for the idea of biased galaxy formation.