Future Directions

As is clear from the previous discussions, while NGC 4038/9 has been modeled with some success, the simulated encounters have failed to reproduce some of the key characteristics of the system. In his 1998 review of galaxy interactions, Josh Barnes outlined four key elements that any improved model of the Antennae must include:

• Matching the observed velocity field - radial velocities of the two galaxies differ by only 40 kms , much lower than those produced in previous models.
• Reconciling the adopted orbit with cosmological expectations - whereas previous simulations adopted elliptical (e ) orbits, parabolic orbits would seem to be more plausible.
• Reproducing the gas rich ring in NGC 4038 - this ring is clearly visible in both the mid-IR and HI maps, and contains many young star clusters.
• Explaining the ``overlap region'' - this dusty region is brighter than either disk in mid-IR wavebands according to recent ISO observations. (Mirabel et al., 1998)