X-ray Emission Mechanism

Even if the metal abundance is left as a free parameter, a Raymond-Smith thermal plasma model provides a poor fit to the jet's spectrum (Section 3.3.2, Tab. 2). Since there is no information on the radio polarization of the jet, we cannot argue against a thermal model on grounds of internal Faraday depolarization, as we did for the western hot spot. The X-ray absorbing column within the jet must be $\lesssim$ 8.4 $\times$ 10$^{20}$ atoms cm$^{-2}$ (the maximum allowed column [Tab. 2] minus the Galactic column), which implies a density n$_{\rm {e}}$ $<$ 0.15 cm$^{-3}$. For the observed X-ray emission to be thermal, the average density of hot gas in the jet (taken to be a cylinder of radius 1 $^{\prime\prime}$ and length 1.'9) is n$_{\rm {e}}$ $\simeq$ 0.05 cm$^{-3}$, compatible with the limits from the absorbing column. Thus the only argument against thermal emission is the poor description of the spectrum by a Raymond-Smith model. We will discuss non-thermal models for the jet in Section 4.3.2.