ABUNDANCE AND EVOLUTION OF QUASARS IN COLD DARK-MATTER MODELS

We invoke the constraints imposed on currently viable inflationary dar k 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 densit y field. Short quasar lifetimes (t(Q) is similar to 10(7)-10(8) yr) co rresponding to quasars radiating at the Eddington limit are required i n order to account for the abundance and number evolution of quasars. Only if the quasar lifetime is approximately 10(7) yr can the tilted C DM 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 mode l, all account for the observed quasar abundance at high redshift.