The CMB cold spot: texture, cluster or void?

TL;DR

This paper evaluates different models explaining the CMB cold spot, finding that a cosmic texture is the most probable cause based on Bayesian analysis, while voids and clusters are unlikely.

Contribution

It provides a Bayesian comparison of texture, void, and cluster models for the CMB cold spot, favoring the texture hypothesis with realistic priors.

Findings

Texture model is favored over void and cluster models.

Void and cluster effects are negligible with realistic parameters.

Bayesian posterior ratios support the cosmic texture explanation.

Abstract

The non-Gaussian cold spot found in the WMAP data has created controversy about its origin. Here we calculate the Bayesian posterior probability ratios for three different models that could explain the cold spot. A recent work claimed that the Spot could be caused by a cosmic texture, while other papers suggest that it could be due to the gravitational effect produced by an anomalously large void. Also the Sunyaev-Zeldovich effect caused by a cluster is taken into account as a possible origin. We perform a template fitting on a 20 degrees radius patch centered at Galactic coordinates (b = -57circ, l = 209) and calculate the posterior probability ratios for the void and Sunyaev-Zeldovich models, comparing the results to those obtained with textures. Taking realistic priors for the parameters, the texture interpretation is favored, while the void and Sunyaev-Zeldovich hypotheses are discarded. The temperature decrement produced by voids or clusters is negligible considering realistic values for the parameters.