Primordial non-Gaussian signatures in CMB polarization

TL;DR

This paper investigates how local primordial non-Gaussianity affects CMB polarization, using statistical tools like PDFs, Minkowski Functionals, and Betti numbers, and finds that E-mode polarization can constrain non-Gaussianity as effectively as temperature data.

Contribution

It introduces a detailed analysis of non-Gaussian signatures in CMB polarization using multiple statistical measures, highlighting the potential of E-mode polarization for constraining primordial non-Gaussianity.

Findings

E-mode polarization provides constraints on $nl$ comparable to temperature fluctuations.

Non-Gaussian deviations in total polarization intensity are weak and dominated by cosmic variance.

The lowest order non-Gaussian deviation in the PDF is at order $(nl \sigma)^2$.

Abstract

We study the signatures of local type primordial non-Gaussianity, parametrized by $\fnl$, of scalar perturbations in CMB polarization using the probability distribution functions, Minkowski Functionals and Betti numbers. We show that the lowest order non-Gaussian deviation of the PDF of the total polarization intensity is at order $(\fnl\sigma)^2$. We calculate the non-Gaussian deviations of Minkowski Functionals and Betti numbers from simulated polarization maps. We find that $E$ mode polarization provides independent and equally strong constraint on $\fnl$ as temperature fluctuations. The non-Gaussian signal in the total polarization intensity, however, is much weaker and has a relatively large cosmic variance and hence may not be useful for detecting local type non-Gaussianity.