  We perform a large parameter survey of 112 collisionless N-body simulations
of binary mergers of disk-galaxies with mass ratios of 1:1, 2:1, 3:1, and 4:1
using the special purpose hardware GRAPE. The basic properties of the remnants
correlate with the mass ratio of the progenitor disks. We find that about 80%
of the equal-mass merger simulations lead to slowly rotating remnants with
significant minor-axis rotation. One half of all projected 1:1 remnants shows
boxy and the other half shows disky isophotes. Remnants with mass ratios of 3:1
and 4:1 all rotate fast and show a small amount of minor-axis rotation. About
90% of the projected 3:1 and 4:1 remnants show disky isophotes. 2:1 remnants
show intermediate properties. Projection effects lead to a large spread in the
data in good agreement with observations. They do not change the fundamental
kinematical differences between equal-mass and unequal-mass merger remnants.
The results of this study weaken the disk merger scenario as the possible
formation mechanism of massive boxy giant ellipticals. In general, the
properties of equal-mass (and 2:1) merger remnants are consistent with the
observed population of giant ellipticals in the intermediate mass regime
between low mass fast rotating disky and bright massive boxy giant ellipticals.
3:1 and 4:1 merger remnants, however, are in very good agreement with the class
of low luminosity, fast rotating giant elliptical galaxies. Binary mergers of
disk galaxies are therefore still very good candidates for being the main
formation mechanism for intermediate and low mass giant ellipticals. The
homogeneous class of massive boxy ellipticals most likely formed by a different
process.

Astrophysics