The CMB cold spot: texture, cluster or void?

ABSTRACT The non-Gaussian cold spot found in the WMAP data has created controversyabout its origin. Here we calculate the Bayesian posterior probability ratios for threedifferent models that could explain the cold spot. A recent work claimed that theSpot could be caused by a cosmic texture, while other papers suggest that it couldbe due to the gravitational effect produced by an anomalously large void. Also theSunyaev-Zeldovich effect caused by a cluster is taken into account as a possible origin.We perform a template fitting on a 20 ◦ radius patch centered at Galactic coordi-nates (b = −57 ◦ ,l = 209 ◦ ) and calculate the posterior probability ratios for the voidand Sunyaev-Zeldovich models, comparing the results to those obtained with texture.Taking realistic priors for the parameters, the texture interpretation is favored, whilethe void and Sunyaev-Zeldovich hypotheses are discarded. The temperature decre-ment produced by voids or clusters is negligible considering realistic values for theparameters.Key words: methods: data analysis - cosmic microwave background

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