NGC 4038/4039 are perhaps the most famous pair of nearby interacting galaxies known for their symmetrically placed tidal tails resembling insect antennae. N-body simulations of the formation of the Antennae's tidal tails allow us to set limits on the total amount of dark matter in the interacting galaxies. Shown below are two simulations using different amounts of dark matter in the galaxy models. The low mass model only contains 4 times as much mass in dark matter as stars while the high mass model contains 30 times as much dark matter. The low mass model easily produces long tidal tails like the real pair while the high mass model fails, producing only short, stubby features. Simulations using intermediate masses show that long tails only arise when the mass of dark matter is less than 10 times the mass of the stars.

Live Antennae

Here are two animations of the collision of the low mass model galaxies - one from a view in the plane of the sky and one looking down onto the orbital plane of the collision. The simulation spans about 2 billion years.

Click to see the movie of the interaction from the observer's point of view.

Click to see the movie of the interaction in the orbital plane

John Dubinski