The cosmic microwave background Cold Spot anomaly: the impact of sky
  masking and the expected contribution from the Integrated Sachs-Wolfe effect
  We re-analyse the cosmic microwave background (CMB) Cold Spot (CS) anomaly
with particular focus on understanding the bias a mask (contaminated by
Galactic and point sources) may introduce. We measure the coldest spot, found
by applying the Spherical Mexican Hat Wavelet transform on 100 000 cut-sky
(masked) and full-sky CMB simulated maps. The CS itself is barely affected by
the mask; we estimate a 94 per cent probability that the CS is the full-sky
temperature minimum. However, approximately 48 per cent (masked fraction of the
mask) of full-sky minima are obscured by the mask. Since the observed minima
are slightly hotter than the full-sky ensemble of minima, a cut-sky analysis
would have found the CS to be significant at approximately 2.2 sigma with a
wavelet angular scale of R = 5 degrees. None the less, comparisons to full-sky
minima show the CS significance to be only approximately 1.9 sigma and less
than 2 sigma for all R. The CS on the last scattering surface may be hotter due
to the integrated Sachs-Wolfe effect in the line of sight. However, our
simulations show that this on average only approximately 10 per cent (about 10
micro K but consistent with zero) of the CS temperature profile. This is
consistent with Lambda and cold dark matter reconstructions of this effect
based on observed line-of-sight voids.
