| Abstract: | We use a WISE-2MASS infrared galaxy catalog matched with Pan-STARRS1 (PS1) galaxies to search for a supervoid in the direction the Cosmic Microwave Background Cold Spot. Our imaging catalog has median redshift z=0.14, and we obtain photometric redshifts from PS1 optical colours to create a tomographic map of the galaxy distribution. The radial 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 underdensity at two angular radii, 5 deg, and 15 deg. The counts in photometric redshift bins show significantly low densities at high significance, 5σ and 6σ , respectively, for the two fiducial radii. The line-of-sight position of the deepest region of the void is z = 0.15-0.25. Our data, combined with an earlier measurement by Granett et al. (2010), are consistent with a large R = (220 ± 50)h−1 Mpc supervoid with δ = -0.14 ± 0.04 centered at redshift z = 0.22 ± 0.03. Such a supervoid, constituting at least a 3.3σ fluctuation in a Gaussian distribution of the ΛCDM model, is a plausible cause for the Cold Spot. |