Non-Gaussianity in the Cosmic Microwave Background Anisotropies at Recombination in the Squeezed limit

TL;DR

This paper analytically estimates second-order CMB temperature anisotropies at recombination in the squeezed limit, finding the contamination to primordial non-Gaussianity is below current experimental sensitivity.

Contribution

It provides an analytical estimate of second-order effects on CMB anisotropies, clarifying the level of contamination to primordial non-Gaussianity in the squeezed limit.

Findings

Contamination level f_NL^{con} is approximately O(1).

Contamination is below current experimental sensitivity.

Results challenge recent claims of higher contamination levels.

Abstract

We estimate analytically the second-order cosmic microwave background temperature anisotropies at the recombination epoch in the squeezed limit and we deduce the contamination to the primordial local non-Gaussianity. We find that the level of contamination corresponds to f_NL^{con}=O(1) which is below the sensitivity of present experiments and smaller than the value O(5) recently claimed in the literature.