Evolution of the luminosity function and colours of galaxies in a Λ cold dark matter universe

The luminosity function of galaxies is derived from a cosmological hydrodynamic simulation of a A cold dark matter universe with the aid of a stellar population synthesis model. At z = 0, the resulting B-band luminosity function has a flat faint-end slope of alpha approximate to -1.15 with the characteristic luminosity and the normalization in fair agreement with observations, while the dark matter halo mass function is steep with a slope of alpha approximate to -2. The colour distribution of galaxies also agrees well with local observations. We also discuss the evolution of the luminosity function, and the colour distribution of galaxies from z = 0 to 5. A large evolution of the characteristic mass in the stellar mass function as a result of number evolution is compensated by luminosity evolution; the characteristic luminosity increases only by 0.8 mag from z = 0 to 2, and then declines towards higher redshift, while the B-band luminosity density continues to increase from z = 0 to 5 (but only slowly at z > 3).