The Density Structure of a Galaxy Influenced by a Massive Companion

Abstract

The tidal influence of a massive galaxy on a non-rotating spherical companion is studied using numerical simulations. The simulations use various values of mass ratio and velocity of collision while the pericentric distance is kept constant. The half-mass radius of the final equilibrium system remains almost the same as that of the initial system with which the simulations started. The central region becomes more compact and the outer region shows expansion. Maximum tidal distension is observed when galaxies undergo collision on parabolic orbits. The surface density profile of the remnant follows an r^1/4^ law up to r = 4R_h_, where R_h_ is the half-mass radius. The profile shows evidence for a tendency to develop bulges in the outer parts in encounters in which the masses of the stellar systems are comparable.