Deficit of Luminous and Normal Red Galaxies in Cosmic Voids

We construct a sample of 10,680 wall galaxies and 3,064 void galaxies with $M_R \lesssim -20$ by cross referencing a void catalog from literature with Baryon Oscillation Spectroscopic Survey (BOSS) CMASS and WiggleZ galaxies, where the CMASS survey targets redder galaxies and the WiggleZ survey targets bluer galaxies. Comparing the density profiles of the red and blue galaxies as a function of the void radius, we find that the number ratio of red-to-blue galaxies increases with distances from the void centers, suggesting a deficit of luminous and normal red galaxies in voids. We find a mean (g -- r) magnitude color of 1.298 and 1.210 for the wall and void galaxies, respectively, when considering the combined red and blue sample, which is found to be a significant difference. However, when considering the blue and red samples separately, we find no significant color difference. We conclude that the constituents galaxies of each population, rather than intrinsic color difference, is the main driver in the apparent average color difference of galaxies in voids and walls, indicating a deficit of luminous and normal red galaxies in voids. Our analysis suggests that the primary environmental-dependence effect on galaxy evolution for normal and luminous galaxies between void and wall regions is manifested in the number of red galaxies, which depends on the environmental-dependent merger history. Using a semi-analytic simulation model, we can successfully reproduce the apparent color difference between the void and wall galaxies.
Comment: 11 pages, 10 figures, accepted to MNRAS