The fundamental plane of galaxy clusters.

In the three—dimensional space defined by the logarithms of central velocity dispersion σ, effective radius R e and mean effective surface brightness I e, elliptical galaxies are confRned in a narrow plane (Dressler et al. 1987; Djorgovski & Davis 1987). Here we discuss the observational evidence for the existence of an analogous relation for galaxy clusters (Schaeffer et al., 1993).