Reproducing cosmic evolution of galaxy population from z = 4 to 0

Abstract

Abstract We present cosmological hydrodynamic simulations performed to study the evolution of galaxy population. The simulations follow timed release of mass, energy, and metals by stellar evolution and employ phenomenological treatments of supernova feedback, pre-supernova feedback modeled as feedback by radiation pressure from massive stars, and quenching of gas cooling in large halos. We construct the fiducial model so that it reproduces the observationally estimated galaxy stellar mass functions and the relationships between the galaxy stellar mass and the host halo mass from z = 4 to 0. We find that the fiducial model constructed this way naturally explains the cosmic star-formation history, the galaxy downsizing, and the star-formation rate and metallicity of the star-forming galaxies. The simulations without the quenching of the gas cooling in large halos overproduce massive galaxies at z < 2 and fail to reproduce galaxy downsizing. The simulations that do not employ the radiation pressure feedback from young stars predict too strong redshift evolution of the mass–metallicity relation. Furthermore, the slope of the relation becomes too steep at low redshift without the radiation pressure feedback. The metallicity dependence in the radiation pressure feedback is a key to explain the observed mass–metallicity relation. These facts indicate that these two processes in addition to supernova feedback are essential for galaxy evolution. Our simple phenomenological model is suitable to construct a mock galaxy sample to study physical properties of observed galaxy populations.