Galaxy Crash
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(Advanced) Influence of Dark Halos

The dark matter halos have a big effect on the merging timescale and the evolution of tidal tails in galaxy collisions. The "Big Halo" option sets the dark matter halo to be four times bigger than in the standard galaxy models. First, make sure that the "friction" box is checked, so that dynamical friction is operating. Then:

  • Set companion mass to one, pericenter distance to 10 kpc, and inclination of both disks to 0. Now click "Big Halo" and run the simulation. How long does it take the galaxies to merge? Compare this to the standard encounter -- how has it changed, and why?
  • What about the tidal tails -- how have they changed? Why?