Computer Modeling of Colliding Galaxies:
Physics and Techniques

Models must capture essential physics:

These processes are all coupled and non-linear!

Gravity: N-body Models

Hydrodynamics: Smoothed Particle Hydrodynamics

Star Formation

How to relate local properties of the gas to the star formation rate?

Not well understood, but a simple parametrization is the Schmidt (1959) law:

Feedback

How to inject energy from supernovae and stellar winds back into the interstellar gas?

We simply don't know!

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