red galaxies. In particular, the distribution of very luminous ($M_r<-22$) galaxies is dominated by red objects when AGN feedback is included, in agreement with observations.

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[Fig. 4. - Predicted rest-frame $u-r$ color distributions (heavy lines) for different dust extiction laws are compared with the Gaussian fit to the SDSS data (from Baldry et al. 2004, dots) for different magnitude bins. The left column refers to the model without the inclusion of AGN feedback, while right column shows the results when AGN feedback is turned on. The distributions are normalized to the total number of galaxies in the magnitude bin. ]{}

At higher redshift, we expect the effect of the AGN feedback directly related to the bright QSO phase to be even more important, due to the enhanced AGN activity at such cosmic epochs. This is first shown in fig. 5, where we show the color-magnitude relation at various redshifts for the model with no AGN energy injection and the model where the AGN feedback is included.

Note that the energy injection from AGN affects appreciably the number of red galaxies at redshifts $z\gtrsim 2$. In particular, at such redshifts, bimodality only appears in the model including the AGN feedback, 