Galaxy collision (Toomre antennae)

What you are seeing: two disk galaxies on a flyby trajectory, integrated with the shared 2D Barnes-Hut quadtree at $O(N \log N)$ . Prograde-prograde geometry, so the tidal field pulls long tails (the iconic Toomre antennae) out of each disk during pericentre

Figure 1. Two-galaxy fly-by under Barnes-Hut gravity, showing the development of Toomre antennae and eventual merger. Method: leapfrog kick-drift-kick, opening angle 0.7, Plummer softening.

disk stars / galaxy1200

separation4.0

approach speed0.70

opening θ0.70

WHAT TO TRY

Vary each control and watch the rail readouts respond.

Compare the diagnostic plot against the live scene.