Galaxy size-mass relation

We explore the environmental dependence of size for a mass-limited subset of our sample at z<0.05, based on distance to the nearest cluster center. We obtain size-luminosity and size-mass relations in good agreement with previous studies. By separating galaxies according to color and morphology, we show that the environmental variation of the overall size-mass relation on megaparsec scales can be understood as the consequence of a changing mixture of subpopulations, rather than `direct' size transformation.

For example, at fixed mass, quiescent (red) late-type galaxies within 2Mpc of a cluster have the same size as quiescent late-type galaxies 30Mpc from the nearest cluster. Our results support individual galaxy assembly histories as the primary determinant of galaxy size. The existence of significantly different, environment-insensitive size mass relations for subpopulations separated by color (star formation rate) and Sersic index (morphology) provides a clear target for calibration of the baryon cycle in cosmological simulations.