Relativistic Flows at the Hotspots of Radio Galaxies and Quasars?

Abstract

We review the broad band properties of X-ray detected hotspots in radio galaxies and quasars. We show that their collective properties can be unified in a framework involving frequency dependent relativistic beaming and varying orientations to the observer's line of sight. The simplest dynamic model consistent with this picture is a slowing-down relativistic flow downstream from the hotspot shock, suggesting that the jet flow remains relativistic to the hotspot distances.