Can a supervoid explain the Cold Spot?

Understand

The discovery of a void of size $\sim200\;h^{-1}$Mpc and average density contrast of $\sim-0.1$ aligned with the Cold Spot direction has been recently reported.

• It has been argued that, although the first-order integrated Sachs-Wolfe (ISW) effect of such a void on the CMB is small, the second-order Rees-Sciama (RS) contribution exceeds this by an order of magnitude and can entirely explain the observed Cold Spot temperature profile.
• In this paper we examine this surprising claim using both an exact calculation with the spherically symmetric Lema\^itre-Tolman-Bondi metric, and perturbation theory about a background Friedmann-Robertson-Walker (FRW) metric.
• We show that both approaches agree well with each other, and both show that the dominant temperature contribution of the postulated void is an unobservable dipole anisotropy.