Abstract

The way that gas collapses into dark matter potentials, and the feedback processes that are produced by the consequent star formation and accreting black holes, determine the present day appearance of galaxies. Despite decades of study, this inter-relationship is still poorly understood. We have used a carefully constructed sample of galaxies, observed in regions close to the lines of sight towards background QSOs for which we have obtained UV spectroscopy, to map out the spatial correlations between inter-galactic (and circum-galactic) gas and galaxies from z~1 to the present day. I will discuss the results of this comparison and also describe how the results can be used to test the sub-grid physics being built into the current generation of hydrodynamical models for galaxy formation, and hence improve our understanding of the dominant physical processes generating the observed galaxy luminosity function.