The Evolution of Radio Sources at Large Redshifts

Abstract

Evolutionary cosmological models in which the radio source population can extend to large redshifts are discussed. Models incorporating exponential and power-law forms of evolution of the average properties of radio sources with cosmological epoch have been computed for world models with Λ = 0; Ω = 1 and Ω = 0. These are compared with the latest observational data and previous analyses of the source counts. It is shown that exponential models are compatible with the observations and do not require a sharp cut-off in the radio source distribution at large redshifts. The luminosity function of radio sources at large redshifts must exhibit a marked maximum-minimum behaviour. The physical interpretation of different laws of cosmological evolution is discussed.