X‐Ray Spectra of Intermediate‐Luminosity, Radio‐loud Quasars

Abstract

We present new hard X-ray spectra of three radio-loud active galactic nuclei (AGNs) of moderately high X-ray luminosity (LX ≈ 1045 ergs s-1; PKS 2349-01, 3C 323.1, and 4C 74.26) obtained with ASCA and BeppoSAX. The X-ray continua are described in all three cases with a power-law model with photon indices Γ ≈ 1.85, modified at low energies by absorption in excess of the galactic value, which appears to be due to neutral gas. At higher energies, an Fe Kα emission line is detected in PKS 2349-01 and 4C 74.26 and is tentatively detected in 3C 323.1. The equivalent widths of the lines are consistent, albeit within large uncertainties, with the values for radio-quiet AGNs of comparable X-ray luminosity. The Fe Kα line is unresolved in 4C 74.26. In the case of PKS 2349-01, however, the inferred properties of the line depend on the model adopted for the continuum: if a simple power-law model is used, the line is resolved at more than 99% confidence with a full width at half-maximum corresponding to approximately 50,000 km s-1 and a rest-frame equivalent width of 230 ± 120 eV; however, if a Compton reflection model is used, the line is found to be a factor of 2 weaker for an assumed full width at half-maximum of 50,000 km s-1. In 4C 74.26, a strong Compton reflection component is detected. Its strength suggests that the scattering medium subtends a solid angle of 2π to the illuminating source. Overall, the spectral indices of these radio-loud quasars are remarkably similar to those of their radio-quiet counterparts. On the other hand, if the absorber is indeed neutral, as our results suggest, this would be consistent with the typical properties of radio-loud AGNs.