Galaxies in the local Universe show a remarkable diversity from giant ellipticals, to impressive grand design spirals, to small and diffuse dwarf systems. The aim of the topic of galaxy formation and evolution is to understand the physical processes responsible for changing galaxies from the irregular balls of gas observed at high redshift, into the diverse but well defined population seen around us today. For example, how important are mergers of galaxies in forming the elliptical population or building the bulges of local spirals? What is the relative importance of gas-rich vs. poor mergers, and major vs. minor mergers, and mergers vs. secular evolution? Do AGN play a role in “quenching” star formation in galaxies? Is radio-mode heating, or mechanical expulsion of gas by AGN more important to the evolution of galaxies?

Here at St Andrews we are involved in a number of major observational surveys. In the very local Universe CALIFA (Calar Alto Legacy Integral Field spectroscopy Area survey) is providing spatially resolved optical spectra for 600 local galaxies - the largest ever integral field survey to cover a representative sample of the local galaxy population. At slightly higher redshift, the GAMA (Galaxy And Matter Assembly ) survey will combine good quality optical spectroscopic observations with the AAT, with multi-wavelength imaging from both ground-based and space-based facilities. Alongside the star formation rates, dust absorption, star formation histories, AGN content and stellar and gas-phase metallicities available from the optical spectra, the multi-wavelength aspect of the survey will provide information on e.g. cold gas from ASKAP (an SKA pathfinder), dust emission from Herschel (ATLAS survey), near-IR morphologies from VISTA (Viking). In the first half of cosmic time (z>1)  CANDELS is obtaining high spatial resolution, deep, NIR imaging of galaxies with the Hubble Space Telescope. At these redshifts, NIR observations are vital for obtaining a complete picture of the stellar populations of galaxies. Using optical wavelengths alone, only the very youngest stars and least dusty galaxies are visible.  To build a complete picture of galaxy evolution we will need to combine knowledge from all these different wavelengths and surveys, probing different physical processes and different cosmic times. In the future the JWST, a replacement for Hubble Space Telescope due to be launched later this decade, and the next generation of extremely large telescopes such as the E-ELT, will provide high quality NIR spectroscopic observations of galaxies just as they are forming.

With the many complex physical processes affecting how we see galaxies, models are important for interpreting our observations. On the theoretical side we are developing sophisticated models of galaxies, using hydrodynamic simulations that capture the important physics of star formation, dust attenuation and nebular emission (see this page). We are developing methods to turn simulations of galaxies into mock observations which can be compared directly to real observations.

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