The fraction of such a gas which is able to radiatively cool settles into a rotationally supported disk with gas mass $m_c$; the disk radius $r_d$ and rotation velocity $r_d$ are computed after the model by Mo, Mao & White (1998). The merging histories of the host haloes, and the dynamical friction and binary aggregations acting on the included sub-halos, are computed adopting the canonical Monte Carlo technique as in Menci et al. (2005). We keep the implementation of gas cooling, star formation and feedback described in the above paper with the same choice of free parameters (the normalization of the star formation timescale and of the feedback efficiency).

The integrated stellar emission from galaxies is computed convolving the star formation rate resulting from our model with the synthetic spectral energy distributions from Bruzual & Charlot (1993), adopting a Salpeter IMF. The dust extinction affecting the intrinsic galactic luminosities is computed assuming the dust optical depth to be proportional to the metallicity of the cold phase (computed assuming a constant effective yield) and to the disk surface density (see Menci et al. 2002 for further details). When no otherwise specified, we assume a Galaxy extinction curve. We have shown in 