An X-Ray Imaging Survey of Quasar Jets: The Complete Survey

H. L. Marshall, J. M. Gelbord, D. M. Worrall, M. Birkinshaw, D. A. Schwartz, D. L. Jauncey, G. Griffiths, J. E.J. Lovell, E. S. Perlman, L. Godfrey

Research output: Contribution to journalReview article (Academic Journal)peer-review

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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 Γx, whose distribution is consistent with a normal distribution, with a mean of 1.61+0.04 -0.05 and dispersion of 0.15+0.04 -0.03. We show that the distribution of α 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+α. We fit Q ∝ (1 + z)a, finding a = 0.88 ±0.90, and reject at 99.5% confidence the hypothesis that the average α 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.

Original languageEnglish
Article number66
JournalAstrophysical Journal
Issue number1
Publication statusPublished - 20 Mar 2018


  • galaxies: active
  • galaxies: jets
  • quasars: general


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