Photometric evolution of galaxies in cosmological scenarios

The photometric evolution of galaxies in a hierarchically clustering universe is investigated. The study is based on high-resolution numerical simulations that include the effects of gasdynamics, shock heating, radiative cooling, and a heuristic star formation scheme. The outcome of the simulations is convolved with photometric models, which enables us to predict the appearance of galaxies in the broadband colors U, B, V, R, I, and K. We demonstrate the effect of the mutual interplay of the hierarchical buildup of galaxies, photometric evolution, k-correction, and intervening absorption on the appearance of forming disk galaxies at redshift 1-3. We also discuss to what extent the numerical resolution of current computer simulations is sufficient to make quantitative predictions on surface density profiles and color gradients.