Making Real Galaxies

Abstract

The final and, in many ways most difficult, part of the story is to put together the astrophysical concepts we have introduced so far in order to form galaxies as we know them at the present epoch. Many of the important processes were introduced in Chap. 16, but there we stopped short of considering, for example, the role of star formation and feedback mechanisms in accounting for the different Hubble types or equivalently, the red and blue sequences. The reason for this is simple – the formation of galaxies as we know them involves a large number of complex interlocking non-linear effects. Many key parts of the picture are poorly understood, for example, the appropriate rules for star formation and its dependence upon the physical conditions within the star-forming region, the role of supernova explosions in enhancing or inhibiting star formation, the role of the massive black holes which form in the centres of massive galaxies, and so on.