The local radio luminosity function of galaxies at 843 MHz

Abstract

Following the investigation of the radio luminosity function by Harnett, two samples of galaxies have been observed with the Molonglo Observatory Synthesis Telescope at 843 MHz. These comprise 176 E and S0 galaxies from the sample by Sadler, and 21 galaxies with δ ≤ -45°, a subset of Harnett's sample. The resulting local radio luminosity function (LRLF) has been extended to radio powers of ≡1018W Hz-1sr-1. At such low luminosities, the irregular galaxies apparently begin to dominate the LRLF. Spirals on the other hand, continue to be confined to radio powers in the range 1019-22W Hz-1sr-1. E and S0 galaxies appear unimportant to the LRLF at low radio luminosities but behave like similar standard candles above powers of ≡1022.5W Hz-1sr-1. The radio properties of S0 galaxies depend on their absolute optical luminosities and hence their masses. The most massive appear similar to radio ellipticals, but at lower optical luminosities comparable to those of spirals, S0 galaxies resemble early-type spirals closely both in their detection rate and correlation between radio and optical luminosities.