Supervoid Origin of the Cold Spot in the Cosmic Microwave Background
  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_{\rm
void}=(192 \pm 15)h^{-1} Mpc $ $(2\sigma)$ supervoid with $\delta \simeq -0.13
\pm 0.03$ centered at $z=0.22\pm0.01$. Such a supervoid, constituting a
$\sim3.5 \sigma$ fluctuation in the $\Lambda CDM$ model, is a plausible cause
for the Cold Spot.
