A Model for the Offsets between X-ray and Radio Emission from Large Scale AGN Jets

We investigate apparent internal structure of kiloparsec scale jets of AGNs arising from the energy dependent cooling of accelerated electrons and light travel time effect for relativistically moving sources. Using a simple cylindrical shell model, we find that the offsets between the peaks of X-ray, optical and radio brightness distributions observed for many cases are basically explained with this model. Assuming that electrons in the moving shell are instantaneously accelerated, X-rays are emitted for a shorter time scale and observed at the side nearer to the nucleus, while radio emission continues to the far side of the nucleus because of longer cooling time. The resultant offset turns out to be order of the jet diameter owing to the light travel time effect.