A STATISTICAL-ANALYSIS OF THE BROAD-BAND 0.1 TO 3.5 KEV SPECTRAL PROPERTIES OF X-RAY-SELECTED ACTIVE GALACTIC NUCLEI

We survey the broadband spectral properties of similar to 500 X-ray-se lected active galactic nuclei (AGNs) observed with the Einstein Observ atory. Included in this survey are the similar to 450 AGNs in the Exte nded Medium Sensitivity Survey of Gioia et al. (1990) and the similar to 50 AGNs in the Ultrasoft Survey of Cordova et al. (1992). We presen t a revised version of the latter sample, based on the post publicatio n discovery of a software error in the Einstein Rev-lb processing. We find that the mean spectral index of the AGNs between 0.1 and 0.6 keV is softer, and the distribution of indices wider, than previous estima tes based on analyses of the X-ray spectra of optically selected AGNs. A subset of these AGNs exhibit flux variability, some on timescales a s short as 0.05 days. A correlation between radio and hard X-ray lumin osity is confirmed, but the data do not support a correlation between the radio and soft X-ray luminosities, or between radio loudness and s oft X-ray spectral slope. Evidence for physically distinct soft and ha rd X-ray components is found, along with the possibility of a bias in previous optically selected samples toward selection of AGNs with flat ter X-ray spectra.