Supervoid Origin of the Cold Spot in the Cosmic Microwave Background

Abstract

We use a WISE-2MASS-Pan-STARRS1 galaxy catalog to search for a supervoid in the direction of the Cosmic Microwave Background Cold Spot. We obtain photometric redshifts using our multicolor data set to create a tomographic map of the galaxy distribution. The radial density profile centred on the Cold Spot shows a large low density region, extending over 10's of degrees. Motivated by previous Cosmic Microwave Background results, we test for underdensities within two angular radii, $5^{\circ }$, and $15^{\circ }$. Our data, combined with an earlier measurement by Granett et al 2010, are consistent with a large $R_{\mathrm{void}}=(192\pm 15)h^{-1}Mpc$ $(2\ddot{I}ƒ)$ supervoid with $\hat{I}´\simeq -0.13\pm 0.03$ centered at $z=0.22\pm 0.01$. Such a supervoid, constituting a $\sim 3.5\ddot{I}ƒ$ fluctuation in the $\hat{I}›CDM$ model, is a plausible cause for the Cold Spot.

4 pages, 2 figures, Proceedings of IAU 306 Symposium: Statistical Challenges in 21st Century Cosmology