Herschel-ATLAS: Evolution of the 250 µm luminosity function out to z = 0.5

We have determined the luminosity function of 250 mu m-selected galaxies detected in the similar to 14 deg(2) science demonstration region of the Herschel-ATLAS project out to a redshift of z = 0.5. Our findings very clearly show that the luminosity function evolves steadily out to this redshift. By selecting a sub-group of sources within a fixed luminosity interval where incompleteness effects are minimal, we have measured a smooth increase in the comoving 250 mu m luminosity density out to z = 0.2 where it is 3.6(-0.9)(+1.4) times higher than the local value.