Simulations of Galaxy Mergers.
Abstract
This work is a theoretical investigation of the mechanisms and results of mergers of elliptical galaxies. An N-body code is developed to simulate the dynamics of centrally concentrated collisionless systems. It is used for N-body simulations of the mergers of galaxies with mass ratios of 1:1, 2:1 and 3:1 with a total of 1200 or 2400 particles. The initial galaxies are spherical and non-rotating with Hubble type profiles and isotropic velocity distributions. The remnants are flattened (up to E4) and are oblate, triaxial or prolate depending on the impact parameter. Equal mass megers are more flattened than unequal mass mergers and have significant velocity anisotropies. The remnants have Hubble type profiles with decreased central surface brightness and increased core radii and tidal radii. In some unequal mass mergers "isothermal" haloes tend to form. The density profiles are inconsistent with De Vaucouleurs profiles even though the initial profiles were not. The central velocity dispersion increases in 1:1 and 2:1 mass mergers but decreases in 3:1 mass mergers. Near head-on mergers lead to prolate systems with little rotation while high angular momentum mergers lead to oblate systems with strong rotation. The rotation curves show solid body rotation out to the half mass radius followed by a slow decline. Radial mixing is strong in equal mass mergers where it will weaken radial gradients. In unequal mass mergers there is little radial mixing but matter from the smaller galaxy ends up in the outer parts of the system where it can give rise to a colour gradient.
- Publication:
-
Ph.D. Thesis
- Pub Date:
- March 1982
- Bibcode:
- 1982PhDT.........2V
- Keywords:
-
- Physics: Astronomy and Astrophysics;
- Computerized Simulation;
- Elliptical Galaxies;
- Galactic Structure;
- Interactions;
- Angular Momentum;
- Density Distribution;
- Galactic Rotation;
- Hubble Diagram;
- Radii;
- Velocity Distribution;
- Astrophysics