Unequal-mass galaxy merger remnants: Spiral-like morphology but elliptical-like kinematics

It is generally believed that major galaxy mergers with mass ratios in the range 1: 1-3:1 result in remnants that have properties similar to elliptical galaxies, and minor mergers below 10: 1 result in disturbed spiral galaxies. The intermediate range of mass ratios 4: 1-10:1 has not been studied so far. Using N-body simulations, we show that such mergers can result in very peculiar systems, that have the morphology of a disk galaxy with an exponential profile, but whose kinematics is closer to that of elliptical systems. These objects are similar to those recently observed by Jog & Chitre (2002). We present two cases with mass ratios 4.5:1 and 7: 1, and show that the merging causes major heating and results in the appearance of elliptical-type kinematics, while surprisingly the initial spiral-like mass profile is conserved.