How structure formed in the Universe is a very active area of astronomy research and still generates a huge amount of debate between astronomers.
The generally accepted model at present is that smaller objects formed first in the Universe, at high redshifts, and that through a series of mergers, began forming the larger galaxies which we see today, as illustrated in Figure 1 below. At redshifts greater than about 0.5, corresponding to an age when the Universe was about 8.5 billion years old, the normal and barred spirals which we see today, disappear, since at these high redshifts, galaxies are still in the process of forming by a series of mergers of smaller galaxies.
It is thought that the ellipitical galaxies which are observed in galaxy clusters, formed through the long process of two galaxies of similar mass, merging together. Even now, our Galaxy, the Milky Way, is in the process of tearing apart some of the smaller galaxies which surround us, leaving faint trails of stars for astronomers to study.
Observations of interacting galaxies give a snap-shot in time of collisions which actually last billions of years. By using computer simulations to model these interactions, astronomers can look into the past and the future of these encounters and look at how structure formed in the Universe.
In this project you will use the Java applet applet, 'Galaxy Crash' (written by Chris Mihos, Case Western University, USA - http://burro.astr.cwru.edu/JavaLab/), to simulate interactions of galaxies. By changing the parameters of each galaxy, you will create tidal tails and elliptical galaxies, and reproduce the types of galaxy interactions which we observe today.
Below are the documents and data files which you will need to carry out this project - start by downloading and reading through the 'Interacting Galaxies Project Instructions' document, then follow the instructions for running the Galaxy Crash applet and producing your own galaxy simulations.