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Major Mergers and the Origin of Elliptical Galaxies

The formation of elliptical galaxies as a result of the merging of spiral galaxies is discussed. We analyse a large set of numerical N-Body merger simulations which show that major mergers can in principle explain the observed isophotal fine structure of ellipticals and its correlation with kinematical properties. Equal-mass mergers lead to boxy, slowly rotating systems, unequal-mass mergers produce fast rotating and disky ellipticals. However, several problems remain. Anisotropic equal mass mergers appear disky under certain projections which is not observed. The intrinsic ellipticities of remnants are often larger than observed. Finally, although unequal-mass mergers produce fast rotating ellipticals, the remnants are in general more anisotropic than expected from observations. Additional processes seem to play an important role which are not included in dissipationless mergers. Resolving these problems might provide interesting new information on the structure and gas content of the progenitors of early-type galaxies.