The Evolution of Radio Quasars with Cosmological Redshift

In this paper, we collect samples of 142 radio quasars(28 radio-quiet quasars and 114 radio-loud quasars), 43 core-dominated quasars, 82 lobe-dominated quasars, and 80 Seyfert galaxies. Based on the Logistic Regression, we analyze the relations of black-hole mass estimates, radio luminosities in 5GHz, Eddington rates, and core-dominated parameter (R) values versus redshifts. We also fit the corresponding evolution curves. Our conclusions are as follows. (1) The evolution of radio quasars is from radio-loud quasars (RLQ) to radio-quiet quasars (RQQ), and at certain stage the transition is from radio quasars to Seyfert galaxies (possibly because energy from accretion cannot maintain the accretion process carsing quasar activities to decline). This supports the view that the differences between RLQ and RQQ are not due to the orientation effect but are results of evolution, and our conclusions confirm the evolution scenario from quasars to Seyfert galaxies proposed by Punsly (1996) and Park (1988). It can explain why RLQs, which tend to have high redshifts, high luminosities, and high accretion rates, likely appear in the early stage of the universe, but all these properties show decrease trends with redshifts and quasar activities began to decline. (2) Core-dominated quasars and lobe-dominated quasars do not show obvious evolution.