Photo-z distributions for the whole (passive and star-forming) population of log(M/M_⊙) > 10.9 galaxies within an aperture of r< 600 kpc from the three passive overdensities as labeled (red lines, errors as from Gehrels 1986). Galaxies and photo-zs used here are from Muzzin et al. (2013b) for CC1003+0223 and CC0958+0158, and from Ilbert et al. (2009) for CC1002+0134 (see text). In each panel, the blue line and dotted area show the median and 16th−84th percentiles of the photo-z distribution (from the same catalogs) in r< 600 kpc apertures at 100 random positions in the COSMOS field, while the grayed-out region shows the redshift range where the sample is no longer mass-complete. Black filled (empty) circles scattered above the histograms (at random y-axis coordinates) show our photo-z determinations for the passive sample used in this work within 300 kpc (600 kpc) from the overdensity center (larger/smaller symbols show galaxies more/less massive than log(M/M_⊙) = 10.9).