Supervoids in the WISE-2MASS catalogue imprinting Cold Spots in the
  Cosmic Microwave Background
  The Cold Spot (CS) is a clear feature in the Cosmic Microwave Background
(CMB); it could be of primordial origin, or caused by a intervening structure
along the line of sight. We identified a large projected underdensity in the
recently constructed WISE-2MASS all-sky infrared galaxy catalogue aligned with
the Cold Spot direction at $(l,b)\approx(209^\circ,-57^\circ)$. It has an
angular size of tens of degrees, and shows a $\sim20\%$ galaxy underdensity in
the center. Moreover, we find another large underdensity in the projected
WISE-2MASS galaxy map at $(l,b)\approx(101^\circ,46^\circ)$ (hereafter Draco
Supervoid), also aligned with a CMB decrement, although less significant than
that of the CS direction. Motivated by these findings, we develop spherically
symmetric Lemaitre-Tolman-Bondi (LTB) compensated void models to explain the
observed CMB decrements with these two underdensities, or "supervoids". Within
our perturbative treatment of the LTB voids, we find that the Integrated
Sachs-Wolfe and Riess-Sciama effects due to the Draco Supervoid can account for
the CMB decrement observed in the same direction. On the contrary, the
extremely deep CMB decrement in the CS direction is more difficult to explain
by the presence of the CS supervoid only. Nevertheless, the probability of a
random alignment between the CS and the corresponding supervoid is disfavored,
and thus its contribution as a secondary anisotropy cannot be neglected. We
comment on how the approximations used in this paper, in particular the
assumption of spherical symmetry, could change quantitatively our conclusions
and might provide a better explanation for the CMB CS.
