X‐Ray Properties of an Unbiased Hard X‐Ray–detected Sample of Active Galactic Nuclei

The Swift gamma-ray observatory's Burst Alert Telescope (BAT) has detected a sample of AGNs based solely on their hard X-ray flux (14-195 keV). In this paper we present for the first time XMM-Newton X-ray spectra for 22 BAT AGNs with no previously analyzed X-ray spectra. If our sources are a representative sample of the BAT AGNs, as we claim, our results present for the first time global X-ray properties of an unbiased toward absorption ( n H < 3 × 10 25 cm −2 ), local ( = 0.03), AGN sample. We find 9/22 low-absorption ( n H < 10 23 cm −2 ), simple power-law model sources, where 4 of these sources have a statistically significant soft component. Among these sources, we find the presence of a warm absorber statistically significant for only one Seyfert 1 source, contrasting with the ASCA results of Reynolds and George and coworkers, who find signatures of warm absorption in half or more of their Seyfert 1 samples at similar redshifts. In addition, the remaining sources (13/22) have more complex spectra, well fitted by an absorbed power law at E > 2.0 keV . Five of the complex sources are classified as Compton-thick candidates. Further, we find four more sources with properties consistent with the hidden/buried AGNs reported by Ueda and coworkers. Finally, we include a comparison of the XMM-Newton EPIC spectra with available Swift X-Ray Telescope (XRT) observations. From these comparisons, we find 6/16 sources with varying column densities, 6/16 sources with varying power-law indices, and 13/16 sources with varying fluxes, over periods of hours to months. Flux and power-law index are correlated for objects where both parameters vary.