Dynamics of Colliding Galaxies
Simulations allow us to watch galaxies collide
Galaxy Merger Animation
(Warning: 2.6 Mb mpeg)
What can we learn from them?
Galaxies merge via dynamical friction against
dark matter halos
- Galaxies plow through one another's dark matter halo,
setting up a trailing wake.
- This wake acts as a ``drag'' on the orbital motion,
causing orbit to decay.
- Galaxies fall together and merge.
Halos ``soak up'' the
orbital energy and angular momentum, essentially making galaxy collisions
Tidal Tails can probe the structure of dark matter
- Tails form when tidal forces ``stretch'' galaxies,
imparting kinetic energy to disk particles.
- The length and mass of tidal tails is sensitive to
the gradient of the gravitational potential.
- Tails can map the potential well of the dark halo.
Studies of tidal tails can constrain
dark matter theories.
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