Radio-loud AGNs without iron Kα lines:: Pictor A and 3C 111

We present the X-ray spectra of the broad-line radio galaxies Pictor A and 3C 111 as observed by ASCA. The main objective of the observations was to detect and study the profiles of the Fe K alpha lines. For Pictor A in particular, the motivation was the fact that the Balmer lines of this object show twin, well-separated peaks, suggesting an origin in an accretion disk. The X-ray spectra of both objects are described very well by a model consisting of a power law modified by interstellar photoelectric absorption. We find evidence for neither a soft nor a hard (Compton reflection) excess. More importantly, we do not detect an Fe K alpha line, in marked contrast with the spectra of typical Seyfert 1 galaxies. The 99%-confidence upper limits on the line equivalent widths are a factor of 2 lower than in Seyfert galaxies of comparable luminosity. We speculate that the absence of a Compton reflection hump and an iron line is an indication of an accretion disk structure that is different from that of Seyfert galaxies.