9 - Young radio sources: evolution and broad-band emission

Summary

Introduction

Radio galaxies represent ideal laboratories to investigate the triggering, maintenance, and fading of AGN activity, as well as the link between these processes and the physical conditions of the environment, from sub- to super-galactic scales. In this context, key sources for the study of the very first phases of the evolution of radio galaxies are the gigahertz-peaked-spectrum (GPS) sources associated with galaxies. From sub-kpc scales, their jet-lobe structures propagate through the host-galaxy interstellar medium (ISM), evolving into sub-galactic (compact-steep-spectrum, CSS) sources, which then expand to super-galactic scales (see O'Dea 1998 for a review). However, this scenario still has several open issues, such as the absorption mechanism responsible for the characteristic turnover in the radio spectrum, the details of the dynamical evolution and interaction with the ISM, the parameters of the central engine, and the origin of the high-energy emission. We recently proposed a model that addresses some of these issues through the analysis of the broad-band emission of GPS galaxies (Stawarz et al. 2008). Here we show that our model satisfactorily reproduces a number of observed properties of X-ray emitting GPS galaxies.

The model: dynamical and spectral evolution

In the following, we recall the main features of our dynamical-radiative model; a more comprehensive discussion can be found in our original paper (Stawarz et al. 2008), and references therein.