Roger J. V. Brissenden

Twenty-two emission-line AGNs from the HEAO-1 X-ray survey

We report 22 emission-line AGN as bright, hard X-ray sources. All of them appear to be new classifications with the exception of one peculiar IRAS source which is a known quasar and has no published spectrum. This sample exhibits a rich diversity in optical spectral properties and luminosities, ranging from a powerful broad-absorption-line quasar to a weak nucleus embedded in a nearby NGC galaxy. Two cases confer X-ray luminosities in excess of 10 exp 47 erg/s. However, there is a degree of uncertainty in the X-ray identification for the AGN fainter than V about 16.5. Optically, several AGN exhibit very strong Fe II emission. One Seyfert galaxy with substantial radio flux is an exception to the common association of strong Fe II emission and radio-quiet AGN. The previously recognized IRAS quasar shows extreme velocities in the profiles of the forbidden lines; the 0 III pair is broadened to the point that the lines are blended. Several of these AGN show evidence of intrinsic obscuration, illustrating the effectiveness of hard X-ray surveys in locating AGN through high column density.

Quasars Contributing to the Extragalactic X-Ray Flux: The Deep X-Ray Survey in Pavo

The nature of discrete x-ray sources contributing to the all-sky x-ray background has been investigated. X-ray selected quasars account directly for ~ 30% of the all-sky x- ray background in the energy range of the Einstein Observatory. Quasars which were not detected in x-rays may account for a further 10–20% of the x-ray background. No examples have yet been found of any class of sources, other than quasars, which might make a comparable or substantial contribution to the extragalactic x-ray background.