Conclusion

While the Universe is dominated by dark matter and this determines the large-scale structure of the dark halos that surround galaxies, the gas fraction is sufficiently large to play an important role in galaxy formaton. In particular, the gas that is the progenitor of the disk is likely to be self-gravitating in many protogalaxies. This means that gas processes played a major role in determining the structure of the visible parts of those galaxies. Until we have a well developed theory for the behaviour of the gas, especially for star formation, we will not have a good understanding of the process of galaxy formation.

© Copyright Astronomical Society of Australia 1997