Radio Emission from Galaxies in the Las Campanas Redshift Survey

To increase the redshift range and look-back time over which the radio luminosity function can be measured directly, we identified 1157 galaxies in the Las Campanas Redshift Survey (LCRS) having isophotal (red) magnitudes m_iso<=18.0 with radio sources brighter than 2.5 mJy beam^-1 in the 1.4 GHz NRAO VLA Sky Survey (NVSS). Since the NVSS has 45" FWHM angular resolution, these radio and optical limits include nearly all LCRS galaxies with 1.4 GHz luminosities L>=10^22.4 W Hz^-1 at z~0.05 to L>=10^23.6 W Hz^-1 at z~0.2. The mean redshift <z>~0.14 of the radio-detected galaxies is higher than the mean redshift <z>~0.10 of the optical sample. This indicates that, statistically, the radio emission was detected from galaxies with the highest optical luminosities. Of the 1157 galaxies, 261 were also identified with far-infrared (FIR) sources in the IRAS Point Source Catalog and Faint Source Catalog. The principal radio energy sources in all identified galaxies were classified as either ``starburst'' or ``AGN'' on the basis of their FIR-radio flux ratios, FIR spectral indices, and radio-optical flux ratios. We show that the radio-optical flux ratio can be effectively used to classify the dominant energy source for the radio emission even if FIR fluxes and radio morphological data are not available.