ASTRONOMY AND ASTROPHYSICS 1.4 GHz luminosity function of galaxies in the Las Campanas redshift survey and its evolution

The sample of 1157 radio-identified galaxies from the Las Campanas Redshift Survey (LCRS) (Machalski & Condon 1999) is used to derive the 1.4 GHz luminosity functions of both star-forming (starburst) galaxies with the mean redshift 〈z〉 ≈ 0.07, and AGN-type ones with 〈z〉 ≈ 0.18. These functions are used as a direct measure of their evolution inferred from the evolutionary models of the entire population of radio sources. Comparing these measured functions with the corresponding local luminosity functions determined by Condon (1989) and Cotton & Condon (1998), we found that assuming the ‘translation evolution’ form of Condon (1984) (also Saunders et al. 1990), the amount of luminosity and/or density evolution in the LCRS sample is of the same order as the uncertainty in determination of the local functions, although the data available do not exclude mild evolution at the rate predicted by the evolutionary models. The above is supported by the starbursttype and AGN-type LCRS galaxies from the bright part of their luminosity functions which produce a spectral power density evidently higher than corresponding UGC galaxies, though the spatial densities of these UGC and LCRS galaxies are comparable. This is consistent with luminosity evolution of galaxies, at least those very luminous within their type.