Abstract Both the Wilkinson Microwave Anisotropy Probe (WMAP) and Planck missions have reported an extremely cold spot (CS) centered at Galactic coordinate (l = 209°, b = -57°) in the cosmic microwave background map. We study the local non-Gaussianity of the CS by defining local Minkowski functionals. We find that the third Minkowski functional ν2 is quite sensitive to the non-Gaussianity caused by the CS. Compared with random Gaussian simulations, the WMAP CS deviates from Gaussianity at more than a 99% confidence level with a scale of R ~ 10°. Meanwhile, we find that cosmic texture provides an excellent explanation for these anomalies related to the WMAP CS, which could be further tested by future polarization data.
Keywords cosmology: cosmic microwave background
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