On the dynamical evolution of hotspots in powerful radio-loud active galactic nuclei

Abstract

We describe the dynamical evolution of hotspots velocity, pressure and mass density in radioloud active galactic nuclei (AGNs), taking proper account of (1) the conservations of the mass, momentum and kinetic energy flux of the unshocked jet, (2) the deceleration process of the jet by shocks and (3) the cocoon expansion without assuming the constant aspect ratio of the cocoon. By the detailed comparison with two-dimensional relativistic hydrodynamic simulations, we show that our model well reproduces the whole evolution of relativistic jets. Our model can explain also the observational trends of the velocity, the pressure, the size and mass density of hotspots in compact symmetric objects (CSOs) and Fanaroff-Riley type II (FRII) radio galaxies. © 2006 RAS.