Cosmic Voids in Sloan Digital Sky Survey Data Release 7

Abstract

We study the distribution of cosmic voids and void galaxies using Sloan Digital Sky Survey Data Release 7 (SDSS DR7). Using the VoidFinder algorithm as described by Hoyle 2002, we identify 1054 statistically significant voids in the northern galactic hemisphere with radii > 10 h^{-1} Mpc. The filling factor of voids in the sample volume is 62%. The largest void is just over 30 h^{-1} Mpc in effective radius. The median effective radius is 17 h^{-1} Mpc. The voids are found to be significantly underdense, with density contrast \delta < -0.85 at the edges of the voids. The radial density profiles of these voids are similar to predictions of dynamically distinct underdensities in gravitational theory. We find 8,046 galaxies brighter than M_r = -20.09 within the voids, accounting for 7% of the galaxies. We compare the results of VoidFinder on SDSS DR7 to mock catalogs generated from a SPH halo model simulation as well as other \Lambda -CDM simulations and find similar void fractions and void sizes in the data and simulations. This catalog is made publicly available at http://www.physics.drexel.edu/~pan/voidcatalog.html for download.