EXTENDED RADIO SOURCES EVOLUTION AND THE ANGULAR SIZE REDSHIFT RELATION

The angular diameter versus redshift relation in the standard FRW model is rediscussed. The present data imply that the standard FRW flat cosmology (q0 = 1/2) cannot be the best-fit model when evolution is absent. By using a simple analytical model to describe the expansion of jets in extended radio sources, a redshift dependence of the proper length of the sources is obtained. For these sources, we show that evolution contributes in such a way that the models can be compatible with the observations of the angular diameter versus redshift cosmological test.