The Luminosity Function of Morphologically Classified Galaxies in the Sloan Digital Sky Survey

The morphological dependence of the luminosity function is studied, using a sample containing approximately 1500 bright galaxies classified into Hubble types by visual inspection, for a homogeneous sample obtained from the Sloan Digital Sky Survey northern equatorial stripes. Early-type galaxies are shown to have a characteristic magnitude 0.45 mag brighter than that of spiral galaxies in the r* band, consistent with the "universal characteristic luminosity" in the B band. The shape of the luminosity function differs rather little among different morphological types: we do not see any symptoms of the sharp decline in the faint end of the luminosity function for early-type galaxies at least 2 mag fainter than the characteristic magnitude, although the faint-end behavior shows a slight decline (α ≲ -1) compared with the total sample. We also show that the rather flat faint-end slope for early-type galaxies is not due to an increasing mixture of dwarf galaxies, which have softer cores. This means that there are numerous faint early-type galaxies with highly concentrated cores.