We study the effect of a massive central singularity on the structure of a triaxial galaxy using N-body simulations. Starting from a single initial model, we grow black holes with various Ðnal masses and Mh at various rates, ranging from impulsive to adiabatic. In all cases, the galaxy achieves a final shape that is nearly spherical at the center and close to axisymmetric throughout. However, the rate of change of the galaxyÏs shape depends strongly on the ratio of black hole mass to galaxy mass. When Mh/Mg the galaxy evolves in shape on a timescale that exceeds 102 orbital periods, or roughly a Mh/Mg[0.3%, galaxy lifetime. When the galaxy becomes axisymmetric in little more than a crossing Mh/MgZ2.5%, time. We propose that the rapid evolution toward axisymmetric shapes that occurs when Mh/MgZ2.5% provides a negative-feedback mechanism that limits the mass of central black holes by cutting o† their supply of fuel. (Refer to PDF file for exact formulas).
Department, Program, or Center
School of Physics and Astronomy (COS)
Astrophysical Journal 498 (26 November 1997)
RIT – Main Campus