X-ray emission properties of large scale jets, hotspots and lobes in active galactic nuclei

We examine a systematic comparison of jet-knots, hotspots and radio lobes recently observed with Chandra and ASCA. The data was compiled at radio (5 GHz) and X-ray frequencies (1 keV) for more than 40 radio galaxies. We examined three models for the X-ray production: synchrotron (SYN), synchrotron self-Compton (SSC) and external Compton on CMB photons (EC). For the SYN sources, X-ray photons are produced by ultrarelativistic electrons with energies 10-100 TeV that must be accelerated in situ. For the other objects, a simple formulation of calculating the "expected" SSC or EC fluxes under an equipartition hypothesis is presented. We confirmed that the observed X-ray fluxes are close to the expected ones for non-relativistic emitting plasma velocities in the case of radio lobes and majority of hotspots, whereas considerable fraction of jet-knots is too bright at X-rays to be explained in this way. We concluded, if the inverse-Compton model is the case, the X-ray bright jet-knots are most likely far from the minimum-power condition. We however prefer the other possibility, namely that the observed X-ray emission from all of the jet-knots is synchrotron in origin.