Large-scale modulation of star formation in void walls

We perform a statistical study of the characteristics of galaxies in voids and void walls in the Sloan Digital Sky Survey and 2dF Galaxy Redshift Survey catalogues. We investigate dependencies of the distribution of galaxy spectral types and colours as a function position to void centres for different luminosity and local density ranges. We find a trend towards bluer, star-forming galaxies in void walls beyond the local density dependence. These results indicate that luminosity and local density do not entirely determine the distribution of galaxy properties such as colours and spectral types, and point towards a large-scale modulation of star formation. We argue that this effect is due to the lower accretion rate and merger histories of galaxies that arriving at void walls from the emptier inner void regions.