  We consider simple semi-analytic models that relate the active galactic
nuclei (AGN) evolution to the merging history of their host dark matter haloes
and quantify their ability of matching the AGN luminosity function and its
spatial clustering at low and intermediate redshifts. In particular, we focus
on the recent determinations of the AGN luminosity function in the hard X-ray
band at z~0 which constitutes the most stringent observational test for our
models. Indeed, while we find an acceptable agreement between the model
bolometric luminosity function and the data at 1<z<2 and for luminosities
larger than 1e10 solar bolometric luminosities, no semi-analytic model is
capable of reproducing the number density of faint X-ray sources in the local
universe. Some improvement can be obtained by advocating energy feedback that
we model through a time-dependent Eddington ratio. Even in this case, however,
the number density of faint AGNs is significantly below observations. This
failure indicates that major mergers cannot constitute the only trigger to
accretion episodes in the local AGN population.
