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Abstract

In this thesis the evolution of galaxies at redshift z < 2 was analyzed, using the COMBO-17+4 (Classifying Objects by Medium-Band Observations) survey. This survey used optical as well as near-infrared data from three different fields of view with a total area of 0.625 square degree. On the basis of an H band selected catalog the photometric redshifts, rest-frame colors and masses of 42,134 galaxies to a limiting magnitude of H = 21.7 mag were calculated. Using the color bimodality in (U280 −V) the galaxies were divided in a red (passive) and a blue (active) population, which were analyzed separately. The results verify the existence of a bimodality up to a redshift of z = 1.6. Further the evolution of the luminosity function for both galaxy populations was analyzed in ten redshift bins. In both populations a significant decrease in the characteristic magnitude M∗B from z = 2 to z = 0.2 was measured. Moreover the number density of red galaxies showed a slight increase during this time, whereas the number density of blue galaxies was decreasing. An analysis of the mass function showed a constant value of the characteristic mass for both populations and an increase of the mass density for red galaxies from z = 2 to z = 0.2.