Formation of ellipticals by unequal mass mergers

Abstract

Collisionless N-body simulations of merging disk-galaxies with mass ratios ($η$) of 1:1, 2:1, 3:1, and 4:1 have been performed using direct summation with the special purpose hardware GRAPE. The simulations are used to examine whether the formation of elliptical galaxies can be explained in the context of the merger scenario. The photometric, kinematical and isophotal properties of the merger remnants are investigated and turn out to be in very good agreement with observations of giant elliptical galaxies. We conclude that equal mass mergers lead to slowly rotating, anisotropic remnants having predominantly boxy isophotes. Mergers with a mass ratio of 3:1 and 4:1, on the other hand, are fast isotropic rotators with disky isophotes. Projection effects can explain the observed scatter in the kinematical and isophotal properties of elliptical galaxies.