X-ray background from evolving QSOs

An analysis of the deep HEAO-2 survey has led us to predict that QSO's up to m_B=20 should emit L_x=.2 L_o if radio-quiet, as compared with 0.7 L_o resulting for catalogued radio-loud; they contribute 20% of the X-ray background at 2 keV. Fainter QSO's can fill up the remaining quota but at the cost of definite and testable predictions on faint star counts and X-ray counts in deeper surveys. Saturation of the background beyond 3 keV, then mandatory, lead to explicit predictions on the spectra of distant QSO's.