Analytical modelling of linear size evolution of powerful radio sources

Krzysztof T. Chyzy

Astronomical Observatory, Jagiellonian University, ul. Orla 171, 30-244 Krakow, Poland

It is assumed that two plasma beams propagate from the core through the ambient medium, create a front shock and expand adiabatically and sideways only, thus producing a lob. Description of global efficiency of conversion of beam bulk energy into other kinds of energy by scaling parameters provides the time evolution of source energy and synchrotron emission. The model predicts a power- law dependence of linear size on spectral radio luminosity and redshift in quantitative agreement with the observed trends for radio galaxies and quasars. The derived linear sizes also depend on the beam characteristics, details of the beam interaction with external medium and the source age, which enable a study of the influence of particular physical processes on the global radio source structure.