In this paper we test the performance of explicit simulations of groups of galaxies, (i.e simulations in which each galaxy is treated as a mass point and the physics of the interactions is modelled by specific analytical prescriptions for merging conditions), by comparing them with fully self-consistent simulations starting from identical initial conditions. The quality of the explicit simulations is very unequal. For some prescriptions the results are in complete disagreement with the self-consistent simulations. The inclusion of other dynamical effects like dynamical friction gives, in some cases, better agreement. We also propose a new merging criterion, which, combined with dynamical friction, gives much better agreement with self-consistent simulations in a variety of initial conditions, but even this criterion has a limited range of applicability.
Astronomy and Astrophysics
- Pub Date:
- September 1996
- GALAXIES: KINEMATICS AND DYNAMICS;
- GALAXIES: INTERACTIONS;
- METHODS: NUMERICAL;
- 17 pages LaTex, 10 Postscript figures, uses a4.sty, a4wide.sty. To appear in A&