ABUNDANCE AND EVOLUTION OF QUASARS IN COLD DARK-MATTER MODELS

We invoke the constraints imposed on currently viable inflationary dark matter models by the abundance of quasars at all redshifts. A simple model for the evolution of the number density of quasars is developed by assuming that the host galaxies form at peaks of the linear density field. Short quasar lifetimes (t(Q) is similar to 10(7)-10(8) yr) corresponding to quasars radiating at the Eddington limit are required in order to account for the abundance and number evolution of quasars. Only if the quasar lifetime is approximately 10(7) yr can the tilted CDM model, with n is similar to 0.7, the scaled (OMEGA(CDM) + OMEGA(A) = 1) CDM model, and the (OMEGA(CDM) = 0.7, OMEGA(nu) = 0.3) mixed model, all account for the observed quasar abundance at high redshift.