N-Body Simulation of a Deeply Penetrating Collision Between Unequal Galaxies

We study the tidal effects of a deeply penetrating collision between two spherical galaxies, one twice massive but less dense than the other, by numerical simulations. We consider the relative motion of the galaxies to be initially in a hyperbolic orbit. The collision parameters are so chosen that the primary (bigger) galaxy is just below the limit of disruption and the relative velocity of the pair is slightly in excess of the escape limit and the primary suffer greater tidal damage than the secondary. The primary develops a core halo structure and shows over all expansion while the secondary while the secondary shows contraction in the inner region and less significant expansion in the outer parts. The initially hyperbolic orbit is transformed into a parabolic orbit as a result of the collision. The result also indicate that the tidal interaction does not induce appreciable rotation in hyperbolic collision. We calculate the angle of deflection of the orbit and compare it with that computed using analytical work. The numerical work shows larger angle of deflection which is attributed to the large tidal effects of the bigger galaxy in the interpenetrating collision. This revised version was published online in July 2006 with corrections to the Cover Date.