Simulations of mergers between disc-halo galaxies

Abstract

A series of more than 30 simulations of the collision and merging of pairs of similar disk-halo galaxies was carried out, the initial systems in these experiments containing equal amounts of mass in a nearexponential disk and in a centrally concentrated nonrotating spheroidal component. The formation of bridges and tails, and the loss and transfer of mass, energy, and angular momentum within the galaxy pair are analyzed in detail. Also examined is the shape and velocity structure of the resulting merger remnants and their dependence upon the initial conditions of the galaxy encounter. It is shown that, if most elliptical galaxies are remnants of single mergers between comparable systems, the initial orbits of these pairs must predominantly have had low angular momenta, and the observed galaxies must be prolate objects.