The Luminosity Function of Galaxies in the Las CampanasRedshift

We present the R-band luminosity function for a sample of 18678 galaxies, with average redshift z = 0:1, from the Las Campanas Redshift Survey (LCRS). The luminosity function may be t by a Schechter function with Over the same absolute magnitude range, the mean galaxy density is 0:029 0:002 h 3 Mpc ?3 for a volume extending to cz = 60000 km s ?1. We compare our luminosity function to that from other redshift surveys; in particular our luminosity function normalization is consistent with that of the Stromlo-APM survey, and is therefore a factor of two below the normalization implied by the b J 20 bright galaxy counts. Our normalization thus indicates that much more evolution is needed to match the faint galaxy count data, compared to minimal evolution models which normalize at b J 20. Also, we show that our faint-end slope = ?0:7, though \shallower" than typical previous values = ?1, results primarily from tting the detailed shape of the LCRS luminosity function, rather than from any absence of intrinsically faint galaxies from our survey. Finally, we nd that the faint end of the luminosity function is dominated by galaxies with emission lines. Using OII] 3727 equivalent width W = 5 A as the dividing line, we nd signiicant diierences in the luminosity functions of emission and non-emission galaxies, particularly in their values; emission galaxies have Schechter parameters M = ?20:03 0:03 + 5 log h and = ?0:9 0:1, while non-emission galaxies are described by M = ?20:22 0:02 + 5 log h and = ?0:3 0:1. The average OII] 3727 equivalent widths do not change signii-cantly with redshift, consistent with a star formation rate which stays constant over the depths sampled by the LCRS. This result holds for galaxies of diierent luminosities, and over the respective redshift ranges that these galaxies may be observed, in particular up to about z = 0:2 for galaxies brighter than M .