G. Migliori, A. Siemiginowska, A. Celotti
We present the X-ray analysis of a deep ~200 ksec Chandra observation of the
compact steep spectrum radio-loud quasar 3C 186 (z=1.06) and investigate the
contribution of the unresolved radio jet to the total X-ray emission. The
spectral analysis is not conclusive on the origin of the bulk of the X-ray
emission. In order to examine the jet contribution to the X-ray flux, we model
the quasar spectral energy distribution (SED), adopting several scenarios for
the jet emission. For the values of the main physical parameters favored by the
observables, a dominant role of the jet emission in the X-ray band is ruled out
when a single zone (leptonic) scenario is adopted, even including the
contribution of the external photon fields as seed photons for inverse Compton
emission. We then consider a structured jet, with the blazar component that-
although not directly visible in the X-ray band - provides an intense field of
seed synchrotron photons Compton-scattered by electrons in a mildly
relativistic knot. In this case the whole X-ray emission can be accounted for
if we assume a blazar luminosity within the range observed from flat spectrum
radio quasars. The X-ray radiative efficiency of such (structured) jet is
intimately related to the presence of a complex velocity structure. The jet
emission can provide a significant contribution in X-rays if it decelerates
within the host galaxy, on kiloparsec scales. We discuss the implications of
this model in terms of jet dynamics and interaction with the ambient medium.
View original:
http://arxiv.org/abs/1202.3153
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