We present a comparison of the properties of galaxies in the most underdense regions of the Universe , where the galaxy number density is less than 10 % of the mean density , with galaxies from more typical regions .
We have compiled a sample of galaxies in 46 large nearby voids that were identified using the Sloan Digital Sky Survey DR4 , which provides the largest coverage of the sky .
We study the u - r color distribution , morphology , specific star formation rate , and radial number density profiles for a total of 495 galaxies fainter than M _ { r } = -20.4 + 5 \log h located inside the voids and compare these properties with a control sample of field galaxies .
We show that there is an excess of blue galaxies inside the voids .
However , inspecting the properties of blue and red galaxies separately , we find that galaxy properties such as color distribution , bulge-to-total ratios , and concentrations are remarkably similar between the void and overall sample .
The void galaxies also show the same specific star formation rate at fixed color as the control galaxies .
We compare our results with the predictions of cosmological simulations of galaxy formation using the Millennium Run semi-analytic galaxy catalog .
We show that the properties of the simulated galaxies in large voids are in reasonably good agreement with those found in similar environments in the real Universe .
To summarize , in spite of the fact that galaxies in voids live in the least dense large-scale environment , this environment makes very little impact on properties of galaxies .