From observations to physics: Cosmological evolution of radio galaxies

Recent theoretical progress has allowed us to determine the influence of the intrinsic properties of radio galaxies and their environments on their luminosity and size evolution. There are still, however, considerable uncertainties regarding our understanding of radio source evolution, in particular the relationship between CSS and GPS sources and larger radio galaxies. Here, we present our preliminary results on the cosmological evolution of the entire radio galaxy population. We use recent analytical models for the dynamical and luminosity evolution of FR II radio galaxies to convert observational data into distributions of source properties such as pressure of the source lobes. As input parameters we use the observed P-D (radio power-linear size) diagrams built up from flux-limited radio samples with complete redshift information. This allows us to examine the environments of evolving radio sources, and to shed more light on the (early) evolutionary tracks of radio galaxies. (C) 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim