On Cosmological Evolution of Quasars

Abstract

Hereafter the term “quasar” is applied to both optically selected (and/or spectroscopically confirmed) UVX objects, and to radio-detected objects of that kind. A recent attempt to model number-counts of radio-selected QSOs (Condon, private communication) has revealed that the counts cannot be modelled by simply translating the general radio luminosity function (RLF) leaving the cosmological evolution unchanged. While it may be true that the radio sources in QSOs evolve in the same way as do all radio sources (i.e. translation function), the radio sources are probably not always in QSOs. In particular, it may be that increasing the luminosity (especially the core luminosity) of a radio source increases the probability that it is in a QSO. If that is true, a radio detection rate of optical QSOs should be strongly dependent on the optical (core) luminosity, i.e. on the absolute magnitude.