Morphological clues to the X-ray emission from extragalactic jets

The mechanism responsible for the kpc-scale emission from extragalactic jets constrains an important quantity: the energy the jet feeds back into the host galaxy and the cluster. Besides spectral data, observations of X-ray/radio positional offsets in these jets’ individual components (or knots) provide an important clue. The first step in utilizing these offsets would be to establish their statistics and any trends that may emerge. We achieve this by performing a detailed comparison between deconvolved Chandra X-ray images of jets and their corresponding radio observations. In several knots of powerful jets, we find the X-rays peak and decay before the radio, questioning the applicability of the widely adopted one-zone interpretation for their observed multi-wavelength emission. The X-rays appear co-spatial with the radio in a nearly equal number of knots. However, they predominantly occur in closely aligned and distant jets, suggesting a significant role of projection and distance-related effects in reducing offsets to below the detectable level. The distribution of offsets and a near periodic inter-knot spacing suggest that knots generally follow similar structures and may be produced when slow-moving portions of the jet plasma act as obstacles to a faster outer flow.