GRAVITATIONAL CLUSTERING OF GALAXIES - COMPARISON OF THERMODYNAMIC THEORY AND N-BODY SIMULATIONS .2. THE EFFECTS OF DIFFERENT MASS COMPONENTS

The thermodynamic theory of gravitational galaxy clustering gives a good description of the galaxy distribution for both N-body simulations and observations. This theory and our previous N-body simulations, however, assume that all the galaxies have the same mass m. We now investigate the effects of mass spectra using new N-body simulations with two mass components (m1 and m2) and find that thermodynamic theory is applicable to two-component systems as long as the mass ratio of two components is in the approximate range of m1:m2 = 1:1-1:10. Our analyses show that the massive galaxies provide nuclei for clusters and speed up clustering in early stages, but these individual effects disappear and collective interactions dominate in late stages. The number of massive galaxies which are contained in clusters tends to increase as the mass ratio becomes larger. We describe the quantitative role that massive galaxies play in seeding clusters. The single-component thermodynamic theory does not describe the N-body simulations for extreme mass ranges of m2/m1 ≳ 15.