  We examine a systematic comparison of jet-knots, hotspots and radio lobes
recently observed with Chandra and ASCA. This report will discuss the origin of
their X-ray emissions and investigate the dynamics of the jets. The data was
compiled at well sampled radio (5GHz) and X-ray frequencies (1keV) 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 -- mostly jet-knots in nearby low-luminosity
radio galaxies -- X-ray photons are produced by ultrarelativistic electrons
with energies 10-100 TeV that must be accelerated in situ. For the other
objects, conservatively classified as SSC or EC sources, a simple formulation
of calculating the ``expected'' X-ray 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 examined two
possibilities to account for the discrepancy in a framework of the
inverse-Compton model: (1) magnetic field is much smaller than the
equipartition value, and (2) the jets are highly relativistic on kpc/Mpc
scales. We concluded, that if the inverse-Compton model is the case, the X-ray
bright jet-knots are most likely far from the minimum-power condition. We also
briefly discuss the other possibility, namely that the observed X-ray emission
from all of the jet-knots is synchrotron in origin.
