Mergers between elliptical galaxies and the thickening of the Fundamental Plane

We have carried out computer simulations to study the effect of merging on the Fundamental Plane (FP) relation. Initially, systems are spherical Jaffe models following a simple scaling relation (M/R²_e= constant). They have been put on the FP by imposing different M/L values. Various orbital characteristics have been considered. Our results show that the merger remnants lie very close to the FP of the progenitors. Although non-homology is introduced by the merging process, mergers among homologous galaxies leave a pre-existing FP-relation intact. As a side result we find that variations in the point of view lead to non-negligible scatter about the FP.