Correlation function (astronomy)

In astronomy, a correlation function describes the distribution of galaxies in the universe. By default, 'correlation function' refers to the two-point autocorrelation function. The two-point autocorrelation function is a function of one variable (distance); it describes the excess probability of finding two galaxies separated by this distance (excess over and above the probability that would arise if the galaxies were simply scattered independently and with uniform probability). It can be thought of as a lumpiness factor - the higher the value for some distance scale, the more lumpy the universe is at that distance scale. In astronomy, a correlation function describes the distribution of galaxies in the universe. By default, 'correlation function' refers to the two-point autocorrelation function. The two-point autocorrelation function is a function of one variable (distance); it describes the excess probability of finding two galaxies separated by this distance (excess over and above the probability that would arise if the galaxies were simply scattered independently and with uniform probability). It can be thought of as a lumpiness factor - the higher the value for some distance scale, the more lumpy the universe is at that distance scale.