Redshift distributions of steep and flat-spectrum radio quasars and relativistic beaming

Abstract

Redshift distributions of almost complete samples of steep as well as flat-spectrum radio quasars are investigated. It is found that flat-spectrum (core-dominated) quasars contain a higher fraction of high redshifts (z ≳ 1.4) compared to steep-spectrum ones. The difference can be understood in the ‘unified scheme’ in which the two types of quasars differ only in the orientation of their jet axes with respect to the observer.