Radio and optical studies of high luminosity IRAS galaxies

Abstract

Follow-up observations of the complete sample of IRAS galaxies are used to identify and describe high luminosity galaxies in the sample. It is found that between 3 and 9 percent of the sample are ultraluminous (IR luminosity greater than 10 to the 12th solar luminosities). VLA observations at 20 cm of the complete IRAS sample indicate that 85 percent of the galaxies are detected above 1 mJy and that the radio emission is, for the most part, centrally located. The linear relation between radio and IR luminosities is valid at the highest luminosities. Of the 11 most luminous objects, one is shown to be a quasar. The other 10 are either close but resolved mergers or double galaxies. Radio observations of the 10 original field sources for this sample indicate that 4 of these are fainter galaxies just outside the IRAS error ellipse with high L(IR)/L(B) values.