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We present the X-ray properties of a sample of 17 radio sources observed with the ChandraX-ray Observatory as part of a project aimed at studying the X-ray emission from their radio jets. In this paper, we concentrate on the X-ray properties of the unresolved cores. The sample includes 16 quasars (11 core-dominated and 5 lobe-dominated) in the redshift range $z=0.30$–1.96, and one low-power radio-galaxy at $z=0.064$. No diffuse X-ray emission is present around the cores of the quasars, except for the nearby low-power galaxy that has diffuse emission on a scale and with a luminosity consistent with other FRIs. No high-amplitude, short-term variability is detected within the relatively short Chandraexposures. However, 1510-089 shows low-amplitude flux changes with a timescale of ~25 min. The X-ray spectra of the quasar cores are generally well described by a single power law model with Galactic absorption. However, in six quasars we find soft X-ray excess emission below 1.6 keV. Interestingly, we detect an Fe K-shell emission line, consistent with fluorescent Kαemission from cold iron, in one lobe- and two core-dominated sources. The average X-ray photon index for the quasars in the sample is $\Gamma_{\rm sample}=1.66$and dispersion $\sigma_{\rm sample}=0.23$. The average spectral slope for our sample is flatter than the slope found for radio-quiet quasars and for radio-loud AGNs with larger jet orientations; this indicates that beaming affects the X-ray emission from the cores in our sample of quasars.

Our spatial and spectral analysis of a recent deep Chandra observation of H1413+117 confirms a microlensing event in a previous Chandra observation of this object performed about 5 years earlier. We present constraints on the structure of H1413+117 based on the time-scale of this microlensing event. The analysis of the combined spectrum of the images indicates the presence of two emission line peaks at rest-frame energies of 5.35 keV and 6.32 keV and detected at the ≳97% and ≳99% confidence levels, respectively. The double peaked Fe emission is fit well with an accretion disk-line model, however, the best-fit accretion disk model parameters are neither well constrained nor unique. Another possible interpretation of the Fe emission is fluorescent Fe emission from the back-side of the wind. Additional observations are required to constrain better the model parameters. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Analysis of several recent ROSATHigh-Resolution Imager (HRI) observations of the gravitationally lensed system Q0957+561 has led to the detection at the 3 ? level of the cluster lens containing the primary galaxy G1. The total mass was estimated by applying the equation of hydrostatic equilibrium to the detected hot intracluster gas for a range of cluster core radii, cluster sizes, and for different values of the Hubble constant. X-ray estimates of the lensing cluster mass provide a means to determine the cluster contribution to the deflection of rays originating from the quasar Q0957+561. The present mass estimates were used to evaluate the convergence parameter ?, the ratio of the local surface mass density of the cluster to the critical surface mass density for lensing. The convergence parameter ?, calculated in the vicinity of the lensed images, was found to range between 0.07 and 0.21, depending on the assumed cluster core radius and cluster extent. This range of uncertainty in ? does not include possible systematic errors arising from the estimation of the cluster temperature through the use of the cluster luminosity-temperature relation and the assumption of spherical symmetry of the cluster gas. Applying this range of values of ? to the lensing model of Grogin & Narayan for Q0957+561 but not accounting for uncertainties in that model yields a range of values for the Hubble constant: 67 < H0< 82 km s-1Mpc-1, for a time delay of 1.1 yr.

Context.X-ray studies of active galactic nuclei (AGN) with powerful nuclear winds are important for constraining the physics of the inner accretion/ejection flow around supermassive black holes (SMBHs) and for understanding the impact of such winds on the AGN environment.

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