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 counterjets were detected. The core spectra are fitted by power law spectra with photon index $Gamma_x$ whose distribution is consistent with a normal distribution with mean 1.61{+0.04}{-0.05} and dispersion 0.15{+0.04}{-0.03}. We show that the distribution of $alpha_{rx}$, the spectral index between the X-ray and radio band jet fluxes, fits a Gaussian with mean 0.974 $pm$ 0.012 and dispersion 0.077 $pm$ 0.008. We test the model in which kpc-scale X-rays result from inverse Compton scattering of cosmic microwave background photons off the jets 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 $Q propto (1+z)^{a}$, finding $a = 0.88 pm 0.90$ 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 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 kpc-scale jets, then the jets must decelerate on average: bulk Lorentz factors should drop from about 15 to 2-3 between pc and kpc scales. Our results compound the problems that the IC-CMB model has in explaining the X-ray emission of kpc-scale jets.
تحميل البحث