092022

The high redshift (z=6.18) quasar CFHQS J142952+544717 shows an extreme X-rayluminosity which is caused by inverse Compton scattering of cosmic Microwavebackground (CMB) photons by the relativistic electrons of the quasars radio jet. As the density of CMB photons increases with increasing redshift such sourcesare more X-ray luminous at higher redshifts to an amount which compensates foreffects of larger distance i.e. XMM-Newton should be able to detect suchCMB-driven X-ray luminous quasars at any redshift. We aim to measure X-rayluminosities of 24 high redshift (z>5.5) radio-detected quasars with the aim tocharacterize the luminosity distribution and establishing further evidence forCMB-driven X-ray emission. [truncated! Please see actual data for full text]