The Rise and Fall of the Quasars
  The coherent rise and fall of the quasar population is discussed in terms of gas accretion onto massive black holes, governed by the hierarchically growing environment. The rise is related to plentiful accretion during the assemblage of the host galaxies; the fall to intermittent accretion when these interact with companions in a group. The LFs are computed out to z=6, and are related to the mass distribution of relict BH found in local galaxies. The histories of the QS and of the star light are compared. 
A. Cavaliere and V. Vittorini (Astrofisica, Dip. Fisica 2a   Universit\`a, Roma)