2016/09/12 by Kathryn McKeough, Aneta Siemiginowska, C. C. Cheung +13 · 1 citation
Physics and Astronomy · #Astrophysical Phenomena and Observations #Astrophysics and Cosmic Phenomena #COSMIC cancer database #Cosmic microwave background #Galaxies: Formation, Evolution, Phenomena #Jet (fluid) #Luminosity #Quasar #Radio galaxy #Redshift #Relativistic beaming #astro-ph.HE
paper · pdf · doi:10.3847/1538-4357/833/1/123
42 pages, 14 figures, submitted to ApJ
arxiv created 2016/09/12 · openalex created_date 2016/09/23 · openalex publication_date 2016/12/10 · arxiv updated 2016/12/21 · openalex updated_date 2026/08/05
ABSTRACT We analyze Chandra X-ray images of a sample of 11 quasars that are known to contain kiloparsec scale radio jets. The sample consists of five high-redshift ( z ≥ 3.6) flat-spectrum radio quasars, and six intermediate redshift (2.1 < z < 2.9) quasars. The data set includes four sources with integrated steep radio spectra and seven with flat radio spectra. A total of 25 radio jet features are present in this sample. We apply a Bayesian multi-scale image reconstruction method to detect and measure the X-ray emission from the jets. We compute deviations from a baseline model that does not include the jet, and compare observed X-ray images with those computed with simulated images where no jet features exist. This allows us to compute p -value upper bounds on the significance that an X-ray jet is detected in a pre-determined region of interest. We detected 12 of the features unambiguously, and an additional six marginally. We also find residual emission in the cores of three quasars and in the background of one quasar that suggest the existence of unresolved X-ray jets. The dependence of the X-ray to radio luminosity ratio on redshift is a potential diagnostic of the emission mechanism, since the inverse Compton scattering of cosmic microwave background photons (IC/CMB) is thought to be redshift dependent, whereas in synchrotron models no clear redshift dependence is expected. We find that the high-redshift jets have X-ray to radio flux ratios that are marginally inconsistent with those from lower redshifts, suggesting that either the X-ray emissions are due to the IC/CMB rather than the synchrotron process, or that high-redshift jets are qualitatively different.