Assessing the Predictive Power of Galaxy Formation Models with the Rest -

— We compare recently measured rest-frame V -band luminosity functions (LFs) of galaxies at redshifts 2.0 ≤ z ≤ 3.3 to predictions of semianalytic models by De Lucia & Blaizot and Bower et al. and hydrodynamic simulations by Davé et al. The models succeed for some luminosity and redshift ranges and fail for others. A notable success is that the Bower et al. model provides a good match to the observed LF at z ∼ 3. However, all models predict an increase with time of the rest-frame V -band luminosity density, whereas the observations show a decrease. The models also have difficulty matching the observed rest-frame colors of galaxies. In all models the luminosity density of red galaxies increases sharply from z ∼ 3 to z ∼ 2.2, whereas it is approximately constant in the observations. Conversely, in the models the luminosity density of blue galaxies is approximately constant, whereas it decreases in the observations. These discrepancies cannot be entirely remedied by changing the treatment of dust and suggest that current models do not yet provide an adequate description of galaxy formation and evolution since z ∼ 3.