NUMERICAL SIMULATIONS OF MERGING GALAXY CLUSTERS

There are observational hints that galaxy clusters may lie close to a Fundamental plane (FP) in the space of their basic observables, total luminosity, effective radius and velocity dispersion, just as elliptic al galaxies do. Seemingly, a transformation of coordinates into the (k (1),k(2),k(3)) coordinate system is possible: for fixed Id, there appe ars to be a small dispersion of k(3) (i.e. of M/L). On the other hand merging of clusters results on temporary departures from virial equili brium, and therefore tends to increase the dispersion about the FP. By means of N-body simulations and with a set of different initial distr ibutions, we study the evolution of clusters in the Je-space during me rging processes, thus setting an upper limit for the recent merging ra te from the observed FP thickness.