Spectral properties of X-ray-selected AGNs

Included in this survey are the ~450 AGNs in the Extended Medium Sensitivity Survey of Gioia et al. (1990ApJS...72..567G) and the ~50 AGNs in the Ultrasoft Survey of Cordova et al. (1992ApJS...81..661C). We present a revised version of the latter sample, based on the post publication discovery of a software error in the Einstein Rev-1b processing.

We find that the mean spectral index of the AGNs between 0.1 and 0.6keV is softer, and the distribution of indices wider, than previous estimates based on analyses of the X-ray spectra of optically selected AGNs. A subset of these AGNs exhibit flux variability, some on timescales as short as 0.05-days. A correlation between radio and hard X-ray luminosity is confirmed, but the data do not support a correlation between the radio and soft X-ray luminosities, or between radio loudness and soft X-ray spectral slope.