Simon Driver, Paul Allen, Alister Graham, Jochen Liske, Nicholas Cross, Ewan Cameron.

Galaxies show a remarkable diversity from giant ellipticals which dominate the cores of rich clusters to very small and diffuse dwarf systems. Quantifying this diversity is still underway with new galaxy populations being discovered (e.g., Ultra-Compact Dwarfs and Blue Spheroids). Making sense of this diversity is perhaps harder. The basic starting point is to associate different 'aspects' of galaxies to distinct formation processes. For examples the collision of two large galaxies is believed to give rise to the giant spheroids whereas gas infall builds 'discs' and secular evolution 'pseudo-bulges'.



Here at St Andrews we are involved in a number of major surveys and in particular the Millennium Galaxy Catalogue, which combines the latest imaging and spectroscopic surveys from both ground-based (INT, UKIRT, VST, VISTA) and space-based facilities (HST, GALEX, SPITZER, JWST). These data are being used to explore new parameter space to identify new galaxy populations, to characterise the known galaxy populations and to provide empirical insight through comparative studies of galaxy samples at different redshifts (lookback times). The core aim is to quantify everything thats out there and identify the key milestones along the galaxy evolution path.

The formation scenario which is emerging from our work is that of a two-stage formation process. With galaxy bulges forming at early times via direct collapse leading to the formation of central super massive black holes and active galactic nuclei. Discs then form later around these bulges through processes such as 'splashback' and 'infall'. Over the next few years we expect to lead a key new survey called GAMA (Galaxy And Matter Assembly) which will build upon the Millennium Galaxy Catalogue to test this theory.