THE LUMINOSITY FUNCTION OF GALAXIES IN THE LAS CAMPANAS REDSHIFT SURVEY

摘要

We present the r-band luminosity function for a sample of 18,678 galaxies, with average redshift z = 0.1, from the Las Campanas Redshift Survey (LCRS). The luminosity function may be fitted by a Schechter function with M~* = -20.29 ± 0.02 + 5 log h, α = -0.70 ± 0.05, and φ~* = 0.019 ± 0.001 h~3 Mpc~(-3), for absolute magnitudes -23.0 ≤ M - 5 log h ≤ -17.5 and h = H_0/(100 km s~(-1) Mpc~(-1)). 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 = 60,000 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 2 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 that normalize at b_J ml 20. Also, we show that our faint-end slope α = -0.7, though "shallower" than typical previous values α = -1, results primarily from fitting the detailed shape of the LCRS luminosity function, rather than from any absence of intrinsically faint galaxies from our survey.