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Angular Correlation Function
The angular correlation function is a function which measures the projected clustering of galaxies, due to discrepancies between their actual and expected distributions. The function may be computed as follows: w(\theta)=\frac\frac-1, where P represents the conditional probability of finding a galaxy, \Omega denotes the solid angle, and N is the mean number density. In a homogeneous universe, the angular correlation scales with a characteristic depth. References Galaxy clusters Equations of astronomy {{Galaxy-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Galaxy Cluster
A galaxy cluster, or a cluster of galaxies, is a structure that consists of anywhere from hundreds to thousands of galaxies that are bound together by gravity, with typical masses ranging from 1014 to 1015 solar masses. Clusters consist of galaxies, heated gas, and dark matter. They are the second-largest known gravitationally bound structures in the universe after superclusters. They were believed to be the largest known structures in the universe until the 1980s, when superclusters were discovered. Small aggregates of galaxies are referred to as galaxy groups rather than clusters of galaxies. Together, galaxy groups and clusters form superclusters. Basic properties Galaxy clusters typically have the following properties: * They contain 100 to 1,000 galaxies, hot X-ray emitting gas and large amounts of dark matter. Details are described in the "Composition" section. * They have total masses of 1014 to 1015 solar masses. * They typically have diameters from 1 to 5 Mpc ( ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
