Our Chandra observation of the FRI radio galaxy 3C 66B has resulted in the first detection of an X-ray counterpart to the previously known radio , infra-red and optical jet .
The X-ray jet is detected up to 7 arcsec from the core and has a steep X-ray spectrum , \alpha \approx 1.3 \pm 0.1 .
The overall X-ray flux density and spectrum of the jet are consistent with a synchrotron origin for the X-ray emission .
However , the inner knot in the jet has a higher ratio of X-ray to radio emission than the others .
This suggests that either two distinct emission processes are present or that differences in the acceleration mechanism are required ; there may be a contribution to the inner knot ’ s emission from an inverse-Compton process or it may be the site of an early strong shock in the jet .
The peak of the brightest radio and X-ray knot is significantly closer to the nucleus in the X-ray than in the radio , which may suggest that the knots are privileged sites for high-energy particle acceleration .
3C 66B ’ s jet is similar both in overall spectral shape and in structural detail to those in more nearby sources such as M87 and Centaurus A .