N-BODY SIMULATION OF THE STEPHAN'S QUINTET

The evolution of compact groups of galaxies may represent one of the few places in the nearby universe in which massive galaxies are being forged through a complex set of processes involving tidal interaction, ram-pressure stripping, and perhaps finally dry mergers of galaxies stripped of their cool gas. Using collisionless N-body simulations, we propose a possible scenario for the formation of one of the best-studied compact groups: Stephan's Quintet. We define a serial approach which allows us to consider the history of the group as a sequence of galaxy-galaxy interactions seen as relatively separate events in time, but chained together in such a way as to provide a plausible scenario that ends in the current configuration of the galaxies. By covering a large set of parameters, we claim that it is very unlikely that both major tidal tails of the group have been created by the interaction between the main galaxy and a single intruder. We propose instead a scenario based on two satellites orbiting the main disk, plus the recent involvement of an additional interloper, coming from the background at high speed. This purely N-body study of the quintet will provide a parameter-space exploration of the basic dynamics of the group that can be used as a basis for a more sophisticated N-body/ hydrodynamic study of the group that is necessary to explain the giant shock structure and other purely gaseous phenomena observed in both the cold, warm and hot gas in the group.