Luminosity-dependent effects on the hot spots in extended double radio sources

Abstract

Following a simple approach based on the beam model for the formation of extended extragalactic double radio sources and assuming that the usual equipartition condition prevails inside their hot spots which are roughly spherical in shape, the authors attempt to explain the observed trend that the hot spots found in sources of lower luminosities are generally more diffuse. It is further argued, that non-relativistic beam velocities (≤0.1c) can only give rise to hot spots of luminosities up to ≡1044erg s-1. For hot spots powered by relativistic beams, much higher luminosities are attainable but a qualitative change in morphology should occur above a luminosity of around 1046erg s-1.