We study the evolution of galaxy populations around the spectroscopic WiggleZ sample of star-forming galaxies at 0.25 \leq z \leq 0.75 using the photometric catalog from the Second Red-Sequence Cluster Survey ( RCS2 ) .
We probe the optical photometric properties of the net excess neighbor galaxies .
The key concept is that the marker galaxies and their neighbors are located at the same redshift , providing a sample of galaxies representing a complete census of galaxies in the neighborhood of star-forming galaxies .
The results are compared with those using the RCS WiggleZ Spare-Fibre ( RCS-WSF ) sample as markers , representing galaxies in cluster environments at 0.25 \leq z \leq 0.45 .
By analyzing the stacked color-color properties of the WiggleZ neighbor galaxies , we find that their optical colors are not a strong function of indicators of star-forming activities such as EW ( [ OII ] ) or GALEX NUV luminoisty of the markers .
The galaxies around the WiggleZ markers exhibit a bimodal distribution on the color-magnitude diagram , with most of them located in the blue cloud .
The optical galaxy luminosity functions ( GLF ) of the blue neighbor galaxies have a faint-end slope \alpha of \sim - 1.3 , similar to that for galaxies in cluster environments drawn from the RCS-WSF sample .
The faint-end slope of the GLF for the red neighbors , however , is \sim - 0.4 , significantly shallower than the \sim - 0.7 found for those in cluster environments .
This suggests that the build-up of the faint-end of the red sequence in cluster environments is in a significantly more advanced stage than that in the star-forming and lower galaxy density WiggleZ neighborhoods .
We find that the red galaxy fraction ( f _ { red } ) around the star-forming WiggleZ galaxies has similar values from z \sim 0.3 to z \sim 0.6 with f _ { red } \sim 0.28 , but drops to f _ { red } \sim 0.20 at z \lower 0.43 pt \hbox { \hbox to 0.0 pt { \raise 2.58 pt \hbox { { { $ \scriptscriptstyle > $ } % } } } \kern - 1.72 pt { { $ \scriptscriptstyle \sim$ } } } 0.7 .
This change of f _ { red } with redshift suggests that there is either a higher rate of star-forming galaxies entering the luminosity-limited sample at z \lower 0.43 pt \hbox { \hbox to 0.0 pt { \raise 2.58 pt \hbox { { { $ \scriptscriptstyle > $ } % } } } \kern - 1.72 pt { { $ \scriptscriptstyle \sim$ } } } 0.7 , or a decrease in the quenching rate of star formation at that redshift .
Comparing to that in dense cluster environment , the f _ { red } of the WiggleZ neighbors is both considerably smaller and has a more moderate change with redshift , pointing to the stronger and more prevalent environmental influences on galaxy evolution in high-density regions .