The evolution of GHz-peaked-spectrum radio sources

Observations of extended radio emission in some GPS sources suggest that they may not be a young version of the classical doubles. The compact source would be confined by the presence of a dense medium in the center of the galaxy. The existence of such a dense environment is supported by the observation of disturbed optical morphologies indicating galaxy-galaxy interaction or mergers. A simple model is formulated to calculate the velocity of advance of the jet as it propagates in a cloudy medium. Different forms of interaction of the jet with the clouds are studied as well as the distribution of gas and clouds on scales smaller than 1kpc around the central engine. It is found that the age of these GPS sources is of the same order as that of the extended radio sources and that the jet propagates either by scattering clouds or by drilling its way through them.