1999ApJ...520...97V

The origin of jets and hot spots in FR II double radio sources are explained by a model in which a supermassive black hole possessing twin beams moves out of the host galaxy with a speed greater than the escape speed. The lobe structure arises as a combination of two trails: the trail of the forward pointing beam is the lobe itself while the backward-pointing beam creates the so-called ``jet'' (narrow linear high-brightness feature). We show that the formation of the ``jet'' depends on the beam angle relative to the line of motion of the black hole. The same angle also controls the amount of entrainment of thermal gas in the lobe, and correlations between the component depolarization and the existence of a jet may arise through this common factor. The high-resolution samples of FR II radio galaxies at z<0.3 by Hardcastle et al. and a representative sample of radio quasars by Bridle et al. are studied for evidence of the beam angle correlation with the jet formation.