An X-Ray imaging survey of Quasar Jets: the complete survey

We present Chandra X-ray imaging of a flux-limited sample of flat spectrum radio-emitting quasars with jet-like structure. X-rays are detected from 59% of 56 jets. No counter-jets were detected. The core spectra are fitted by power-law spectra with a photon index Gamma(x), whose distribution is consistent with a normal distribution, with a mean of 1.61(-0.05)(+0.04) and dispersion of 0.15(-0.03)(+0.04). We show that the distribution of alpha(rx), the spectral index between the X-ray and radio band jet fluxes, fits a Gaussian with a mean of 0.974 +/- 0.012 and dispersion of 0.077 +/- 0.008. We test the model in which kiloparsec-scale X-rays result from inverse Compton scattering of cosmic microwave background photons off the jet's relativistic electrons (the IC-CMB model). In the IC-CMB model, a quantity Q computed from observed fluxes and the apparent size of the emission region depends on redshift as (1 + z)(3+alpha). We fit Q proportional to (1 + z)(a), finding a = 0.88 +/- 0.90, and reject at 99.5% confidence the hypothesis that the average alpha(rx) depends on redshift in the manner expected in the IC-CMB model. This conclusion is mitigated by a lack of detailed knowledge of the emission region geometry, which requires deeper or higher resolution X-ray observations. Furthermore, if the IC-CMB model is valid for X-ray emission from kiloparsec-scale jets, then the jets must decelerate on average: bulk Lorentz factors should drop from about 15 to 2-3 between parsec and kiloparsec scales. Our results compound the problems that the IC-CMB model has in explaining the X-ray emission of kiloparsec-scale jets.