The jet-disk connection in AGNs:: Chandra and XMM-Newton observations of three powerful radio-loud quasars

The connection between the accretion process that powers AGNs and the formation of jets is still poorly understood. Here we tackle this issue using new, deep Chandra and XMM-Newton observations of the cores of three powerful radio-loud quasars, 1136-135, 1150+497 (Chandra), and 0723+679 (XMM-Newton), in the redshift range z = 0.3-0.8. These sources are known from our previous Chandra snapshot survey to have kiloparsec-scale X-ray jets. In 1136-135 and 1150+ 497, evidence is found for the presence of diffuse thermal X-ray emission around the cores, on scales of 40-50 kpc and with luminosity L(0.3-2 keV) similar to 10(43) ergs s(-1), suggesting thermal emission from the host galaxy or a galaxy group. The X-ray continua of the cores in the three sources are described by an upwardcurved (concave) broken power law, with photon indices Gamma(soft) similar to 1.8-2.1 and Gamma(hard) similar to 1: 7 below and above approximate to 2 keV, respectively. There is evidence for an unresolved Fe K alpha line with EW similar to 70 eV in the three quasars. The spectral energy distributions of the sources can be well described by a mix of jet and disk emission, with the jet dominating the radio and hard X-rays (via synchrotron and external Compton radiation) and the disk dominating the optical/UV through soft X-rays. A comparison of the kiloparsec- scale with the parsec-scale jet powers shows that the two agree within a factor of 2, confirming previous findings for gamma-ray blazars. This suggests that the power channeled into the jet is stable on timescales of the order of 10(4)-10(5) yr and that a negligible fraction of the kinetic power of the jet is dissipiated along its path from the innermost regions of the AGN to the hundreds of kiloparsec scales.