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 based on the original VoidFinder method devised by El-Ad & Piran and implemented by Hoyle & Vogeley, 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 per cent. 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 δ < − 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 8046 galaxies brighter than M_r=− 20.09 within the voids, accounting for 7 per cent of the galaxies. We compare the results of VoidFinder on SDSS DR7 to mock catalogues generated from a smoothed particle hydrodynamics (SPH) halo model simulation as well as other Λ cold dark matter (ΛCDM) simulations and find similar void fractions and void sizes in the data and simulations. This catalogue is made publicly available at http://www.physics.drexel.edu/~pan/VoidCatalog for download.