The cosmic microwave background Cold Spot anomaly: the impact of sky masking and the expected contribution from the Integrated Sachs-Wolfe effect

Understand

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.