1996A&A...310..757S

This is the second article of a series devoted to the dynamical study of nearly radial collisions between an elliptical galaxy and a small satellite. We here present a set of restricted and full N-body simulations which complement our analytical work (Seguin & Dupraz 1994) and emphasise the role played by the various parameters of the collision. Using a "Particle-Mesh" code, we follow the orbital decay of the satellite in the course of the collision and show that the two processes responsible for the accretion - dynamical friction and tidal stripping - have a concurrent rather than complementary influence on the sinking satellite. Shell formation around the elliptical is discussed in the light of this competition. Special attention is paid to highly eccentric collisions. Our results indicate that dynamical friction is much less sensitive to the value of the impact parameter than tidal forces. If the core of the satellite is to survive and merge with the galaxy, the optimal configuration involves a compact dwarf on a slightly non-radial encounter. We also stress the inadequacy of Chandrasekhar's formula as an empirical description of dynamical friction along head-on encounters. In contrast with the circular case, the phenomenon is dominated by the transient nature of the galactic response. This and some astrophysical implications will be discussed in a forthcoming article (Seguin & Dupraz 1995, in preparation).