The formation of disks in elliptical galaxies

We investigate detailed kinematical properties of simulated collisionless m erger remnants of disk galaxies with mass ratios of 1 : 1 and 3 : 1. The si mulations are performed by direct summation using the new special hardware device GRAPE-5. In agreement with observations, the shape of the line-of-si ght velocity distribution (LOSVD) is Gaussian with small deviations. For mo st cases, we find that the retrograde wings of the LOSVD are steeper than t he prograde ones. This is in contradiction with observations that show broa d retrograde and steep prograde wings. This serious problem in the collisio nless formation scenario of massive elliptical galaxies can be solved if al l rotating elliptical galaxies, even boxy ones, contain an additional stell ar disk component of approximately 15% of the total stellar mass and a scal e length of order the effective radius of the spheroid. We propose that the progenitor galaxies of massive elliptical galaxies must have contained a s ignificant amount of gas that did not condense into stars during the merger process itself but formed an extended gaseous disk before the star formati on epoch. The heating source that prevented the gas from forming stars earl y and the origin of the large specific angular momentum required for the ga s component to form an extended disk are still unsolved problems.