The growth of correlations in an expanding universe and the clustering of galaxies.
Abstract
The paper considers the question: if the universe consisted of unclustered galaxies at some time after matter and radiation decoupled, would the instability of a gravitational system to clustering be sufficient to account for the level of galaxy clustering observed now. A theory of galaxy clustering is developed for a general system of selfgravitating point particles in an expanding homogeneous and isotropic Newtonian cosmological model. The basic equation for the early development of the pair correlation function is derived from the BBGKY hierarchy of kinetic equations, this equation is solved explicitly for the full correlation function, and the full function is used to determine the spatial correlation function as well as its regime of validity. The physical significance of the correlation functions is discussed, and the model is compared with observational data. It is concluded that the instability of a gravitational system consisting of discrete objects as massive as galaxies is probably strong enough to produce the observed level of clustering.
 Publication:

The Astrophysical Journal
 Pub Date:
 March 1976
 DOI:
 10.1086/154212
 Bibcode:
 1976ApJ...204..631F
 Keywords:

 Big Bang Cosmology;
 Correlation;
 Galactic Clusters;
 Gravitational Effects;
 Universe;
 Astronomical Models;
 Bbgky Hierarchy;
 Newton Theory;
 Spatial Distribution;
 Time Functions;
 Astrophysics