An evolutionary model for GHz peaked spectrum sources - Predictions for high frequency surveys

We have explored, in the general framework of the "young source" scenario, evolutionary models for GHz Peaked Spectrum (GPS) galaxies and quasars whic h reproduce the observed counts, redshift and peak frequency distributions of currently available samples. Substantially different cosmological evolut ion properties are found for the two populations: the quasar luminosity fun ction must evolve strongly up to z similar to 1, while the data on galaxies may be consistent with no evolution. The models show that GPS sources (mos tly quasars) may comprise quite a significant fraction of bright (S > 1 Jy) radio sources at v greater than or equal to 30 GHz if the intrinsic distri bution of peak frequencies extends up to similar to 1000 GHz. In any case, however, their fraction decreases rapidly with decreasing flux and their co ntribution to small scale fluctuations in the frequency range covered by th e forthcoming space missions MAP and Planck Surveyor is expected to be mino r.