Environmental dependence of different colors in the CMASS sample of the   SDSS DR9
  In this study, I investigate the environmental dependence of galaxy colors in the CMASS sample of the Sloan Digital Sky Survey Data Release 9 (SDSS DR9). To decrease the radial selection effect, I divide the CMASS sample into subsamples with a redshift binning size of 0.01 and analyze the environmental dependence of the u-r, u-g, g-r, r-i and i-z colors for these subsamples in each redshift bin. Statistical analysis shows that all the five colors weakly correlate with the local environment, which may mean that the environmental processes responsible for a galaxy's properties proceed slowly over cosmic time. 
Xin-Fa Deng
astro-ph.CO