The CMB cold spot: texture, cluster or void?

The non-Gaussian cold spot found in the Wilkinson Microwave Anisotropy Probe (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. Furthermore, the Sunyaev–Zeldovich effect caused by a cluster is taken into account as a possible origin. We perform a template fitting on a 20° radius patch centred at coordinates (b=−57°, l= 209°) and calculate the posterior probability ratios for the void and Sunyaev–Zeldovich models, comparing the results to those obtained with texture. Taking realistic priors for the parameters, the texture interpretation is favoured, 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.