The evolutionary unified scheme. I. Quasars and radio galaxies in the viewing angle-redshift plane

We present a study of the distribution of quasars and radio galaxies in the viewing-angle-redshift plane in the framework of the evolutionary unified scheme (Vagnetti, Giallongo, and Cavaliere 1991). Results are presented for some illustrative cases, including a distribution of the Lorentz factors and appropriate luminosity functions for quasars and their host galaxies. A cosmologically increasing [Gamma] is found, in agreement with the previous paper. It is argued that the appearance of sources as quasars or radio galaxies can depend on the viewing angle and on the redshift, due to the balance between the beamed component and the luminosity of the host galaxy. Within the assumptions of our evolutionary unified scheme, we find that low-Gamma objects can be observed as quasars mainly at z greater than or similar to 0.3, while a substantial fraction of the low-z radio galaxies could consist of quasar remnants.