Dynamical Evolution of Elliptical Galaxies with Central Singularities
Abstract
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 final masses Mh and 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 galaxy's shape depends strongly on the ratio Mh/Mg of black hole mass to galaxy mass. When Mh/Mg <~ 0.3%, the galaxy evolves in shape on a timescale that exceeds 102 orbital periods, or roughly a galaxy lifetime. When Mh/Mg >~ 2.5%, the galaxy becomes axisymmetric in little more than a crossing time. We propose that the rapid evolution toward axisymmetric shapes that occurs when Mh/Mg >~ 2.5% provides a negative-feedback mechanism that limits the mass of central black holes by cutting off their supply of fuel.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- May 1998
- DOI:
- 10.1086/305579
- arXiv:
- arXiv:astro-ph/9709106
- Bibcode:
- 1998ApJ...498..625M
- Keywords:
-
- BLACK HOLE PHYSICS;
- GALAXIES: ELLIPTICAL AND LENTICULAR;
- CD;
- GALAXIES: NUCLEI;
- GALAXIES: STRUCTURE;
- METHODS: NUMERICAL;
- Black Hole Physics;
- Galaxies: Elliptical and Lenticular;
- cD;
- Galaxies: Nuclei;
- Galaxies: Structure;
- Methods: Numerical;
- Astrophysics
- E-Print:
- 27 Latex pages, 9 Postscript figures, uses aastex.sty. Accepted for Publication in The Astrophysical Journal, Nov. 26, 1997