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The X-ray emission of radio-loud (RL) AGNs is a powerful tool for probing the structure of the accretion flow in these objects. We review recent spectral and variability studies of RL AGNs, which show that these systems have systematically different X-ray properties than their radio-quiet (RQ) counterparts. Specifically, RL AGNs have weaker and narrower Fe Kα lines and weaker Compton reflection components above 10 keV. The nuclear continuum of RL AGNs in the 2-10 keV band is well described by a power law with photon indices ∼ 1.8, similar to RQ AGNs of comparable X-ray luminosity. RL AGNs have little or no flux variability on short time scales (... 0.5 days); however, flux and spectral variations are observed on time scales of weeks in two well-monitored objects, 3C 390.3 and 3C 120. These properties strongly suggest that the central engines of the two AGNs classes are different. We discuss the implications of these observational results, in particular the possibility that the central engines of RL AGNs are harbor an ion torus (also known as an Advection-Dominated Accretion Flow or ADAF). We show that a beamed component from the jet is unlikely in the majority of sources. Moreover, the X-ray data provide evidence that the circumnuclear environs of RL and RQ AGNs also differ: large amounts of cold gas are detected in BLRGs and QSRs, contrary to Seyfert galaxies of similar X-ray luminosity where an ionized absorber seems to be the norm. The role of future X-ray missions in advancing our understanding of the central engines of RL AGNs is briefly highlighted. [ABSTRACT FROM AUTHOR]

We present five spectra of the quasar HS1603+3820 (zem=2.542) taken over intervals of 0.2–1.6 years (0.7–5.4 months in the quasar rest frame) with the High Dispersion Spectrograph on the Subaru telescope, for the purpose of studying its intrinsic narrow absorption lines (NALs). This quasar shows a rich complex of C IV NALs near the emission redshift (dN/dz ∼ 12). We perform time variability analysis as well as covering factor analysis to separate intrinsic NALs, which are physically related to the quasar, from intervening NALs in 8 C IV systems. Only one of them, at zabs ∼ 2.43, shows both partial coverage and large variation in line strength, width, and position. Assuming that a change in the ionization state of the absorber causes the variability, a lower limit can be placed on the electron density (ne > 3.2 × 104 cm-3) and an upper limit on the distance from the continuum source (r < 6 kpc). On the other hand, if motion of clumpy gas causes the variability, the crossing velocity and the distance from the continuum source are estimated to be νcross > 8,000 km s-1 and r < 3 pc, assuming that the observed shift velocity does not exceed the escape velocity at that radius. If we adopt the dynamical model of Murray et al. (1995), we can obtain a much more strict constraint on the radius of the gas parcel, r < 0.2 pc. We are planning to monitor this quasar for several years so as to use intrinsic absorber’s behavior as a direct check of wind models. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

A long XMM-Newton observation of the mini-BAL QSO PG 1126-041 allowed us to detect a highly ionized phase of X-ray absorbing gas outflowing at ν∼15000 km s-1. Physical implications are briefly discussed. [ABSTRACT FROM AUTHOR]