Gas Infall and Stochastic Star Formation in Local Galaxies

Guinevere Kauffmann

The physical processes that regulate the rate at which galaxies form stars and the timescale over which galaxies evolve from star-forming to passive systems are still not understood. I discuss how an analysis of the scatter in the colours and spectral properties of galaxies can be used to constrain their past star formation histories. I use a sample of 400,000 galaxies from the Sloan Digital Sky Survey and new high resolution numerical simulations of structure formation to construct a simple model for the rate at which galaxies have been accreting gas and forming their stars over the past few Gyr.