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

TL;DR

This paper presents a model explaining the observed offsets between X-ray, optical, and radio emission peaks in large-scale AGN jets, attributing them to energy-dependent electron cooling and light travel time effects in relativistic jets.

Contribution

It introduces a simple cylindrical shell model that accounts for the observed emission offsets based on electron cooling times and light travel effects in AGN jets.

Findings

Offsets are explained by the model as due to cooling and light travel time effects.

X-ray emission occurs nearer to the nucleus, radio farther away, consistent with observations.

Offsets are approximately the size of the jet diameter.

Abstract

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.