changes in the temperature ($\Delta T/T\lesssim 0.1$) and hot gas mass ($\Delta m/m_h \lesssim 0.05$) remain much smaller than one.

The Bimodal Color Distribution of Galaxies
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The effect of the energy injection from AGNs on the color distribution of local galaxies is shown in fig. 4 for three luminosity bins, and compared with the data from the Sloan survey (SDSS) given in Baldry et al. (2004) for the $u-r$ colors; details on the SDSS $u$ and $r$ bands are given by the above authors. As expected, the AGN feedback affects only the color distribution of luminous galaxies; this is due to their larger cross section for interactions (triggering the AGN activity) and to the larger fraction of destabilized gas accreted by the SMBH (powering the AGN activity). Note also that both the [*bimodal partition*]{} and the [*downsizing*]{} (i.e., the correlation bewetten the age of the stellar population, or the color, and the galaxy luminosity) are not determined by the AGN feedback, as we showed in our previuous paper and as confirmed by the recent results by Croton et al.(2006). Rather, the AGN feedback affects the partition of galaxies between the blue and the red population, enhancing the fraction of 