A cosmic virial theorem

A new type of cosmic virial theorem is derived, representing a relation among the two-point and three-point galaxy correlation functions and the mean square relative peculiar velocity <γ2(r)> averaged over pairs of galaxies separated by distance r. The two correlation functions seem to be fairly well known, but <γ2(r)> at best is only very roughly estimated from available data. It might be possible to improve the estimate through a systematic program of redshift measurements in sample areas. If so, the cosmic virial theorem might yield an interesting measure of the mean mass density due to galaxies. (Auth.)