Non-Gaussianity of the distribution tails in CMB

We analyze statistical properties of the separate multipole moments of the CMB temperature maps and find that the distribution tails are slightly non-Gaussian. Moreover, the deviation from Gaussianity peaks sharply at around $l\sim45\pm10$. If the detected non-Gaussianities should be attributed to the remaining foreground contamination from the galactic plane, an appearance of a similar peak in different frequency bands is unexpected. The presence of the peak was also confirmed by the analysis of weighted multipoles which is less susceptible to the galactic noise. A separate analysis of the multipoles with odd and even $l+m$ shows two opposite types of non-Gaussianities which cannot be explained with only galactic foregrounds. We argue that cosmic strings or correlated gravitational waves could lead to the observed effect.