Linking radio to infrared: a radio source count model

Abstract

We investigate the populations and evolution of normal and active galaxies by extending the infrared source count model of Rowan-Robinson (2001) into the radio. The FIR-radio correlation is used to extend the SEDs to the radio region and it is assumed that there are two distinct populations of quasar: radio loud and radio quiet. It is found that the radio luminosity function and source count data are best fit when the fraction of quasars that are radio loud is allowed to increase with optical luminosity. This implications for this are discussed, as are the possible causes for the variation in radio loud fraction.