Correlations among color,morphology, and luminosity for the luminous red galaxy (LRG) sample of the SDSS data release 5

We have investigated the correlations among color, morphology and luminosity for all LRGs, cut I LRGs, cut II LRGs, and Main galaxies that are also classified as LRGs. It is found that the morphology of LRGs is tightly correlated with luminosity. The rest-frame u-g color of cut I LRGs and cut II LRGs is nearly independent of luminosity, but the color of Main galaxies is correlated with luminosity. For cut I LRGs and Main galaxies, the early type proportion apparently changes with color: at the rest-frame u-g < 1.3 it increases strongly with increasing color, while at the rest-frame u-g > 1.3 it decreases with increasing color. We also notice that the morphology of cut II LRGs is only a weak function of color. Published in Astrofizika, Vol. 50, No. 3, pp. 335–345 (August 2007).