Remnants of Strong Tidal Interactions

This paper examines the properties of stellar systems that have recently undergone a strong tidal shock, i.e., a shock which removes a significant fraction of the particles in the system, and where the shocked system has a much smaller mass than the producer of the tidal field. N-body calculations of King models shocked in a variety of fashions were performed, and the consequences of such shocks were investigated. The energy distributions of both stripped particles and those of the remnants are examined, as well as the density profiles of the remnants. Simple density profiles, which are based upon an understanding of the tidal shock as causing essentially random perturbations in energy, appear to fit the resulting profiles relatively well with ρ is proportional to r^-4^ and a relatively flat N(E). Although the remnant systems are round, the orbits of the remnant particles appear to be only weakly dependent on the angular momentum integrals. These results confirm the prediction of Jaffe for shocked systems. His analytic results are extended beyond the special case he considered. Several models were also run where the tidal forces on the system were constant, simulating a circular orbit around a primary, and the development of tidal radii under these static conditions appears to be a mild process which does not dramatically affect material that is not stripped. The tidal radii are approximately twice as large classical formulae would predict. The parameters of the core of the system are negligibly affected by stripping of as much as 30% of the exterior. Whether a particle is stripped does not appear to be much affected by its angular momentum, although there is some dependence on whether the orbit is retrograde or prograde. Remnant density profiles were compared with a sample of elliptical galaxies, and some of the galaxies which might be expected to show tidal effects do show outer profiles similar to those of the simulations, particularly the fainter elliptical galaxies. The implications of these results for the development of the globular cluster system and older stellar population in our Galaxy, and for the evolution of companion galaxies and of galaxies in crowded environments, are discussed.