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Session 49 - Elliptical Galaxies & Bulges.
Display session, Thursday, January 08
The survival of dense secondaries in simulations of purely stellar mergers presents a formidible problem for the persistence of the core fundamental plane. As we presented in our last set of experiments, the subtle effects of resonant heating and tidal stripping are not enough to destroy the dense secondaries which lie on this plane. In this paper, we demonstrate the effect that central black holes have upon mergers with high density constrasts. The large dynamic range in density between the two galaxies makes this an expensive problem to investigate with a traditional N-body approach. Therefore, we have developed an efficient technique which is well-suited to simulate mergers of systems with widely varying densities. This technique takes advantage of the high density of the secondary by approximating this galaxy as a point particle in the frame of the accretor. In this inertial frame, we can determine the orbital decay of the center of the secondary due to dynamical friction. The secondary can then be followed in a separate, inertial frame simulation that includes the external force of the primary on each secondary particle. Preliminary results of our experiments indicate that it is the excellent scattering ability of black holes at the centers of primaries that causes the canibalization of dense, fundamental plane galaxies. The persistence of the core fundamental plane, then, may be a statement that central black holes are a common feature of large galaxies.
Program listing for Thursday