Annu. Rev. Astron. Astrophys. 1991. 29: 239-274 Copyright © 1991 by Annual Reviews. All rights reserved

4.4 Galaxy Formation at z = 0?

Given the difficulty in observing high redshift galaxies, we may ask which aspects of the formation process we can see in the nearby universe. Ongoing mergers of spiral galaxies provide unique laboratories for a study of the physics of encounters, and they have been modeled in detail by various authors (52, 53, 157, 334). The current simulations are very successful in reproducing most observables, and can be used to constrain the orbits and halo properties of the merging galaxies. The end results of these encounters are expected to resemble bright elliptical galaxies (15, 17).

One of the most interesting aspects of investigations of this type is that they may result in a better understanding of the gas dynamics and star formation during the encounter. Hernquist has shown that gas can be driven into the centers of galaxies during the encounter (156). This provides a natural mechanism for nuclear starbursts and/or nuclear activity. The gas masses and star formation rates in starbursts can be quite high, and these events may be typical of the events that formed the stars in most galaxies.