The Impact of Secondary non-Gaussianities in the CMB on Cosmological Parameter Estimation

TL;DR

This paper investigates how secondary non-Gaussian effects like lensing and the Sunyaev-Zel'dovich effect influence the covariance of CMB temperature anisotropy spectra, affecting the precision of cosmological parameter estimation.

Contribution

It introduces a method to incorporate secondary non-Gaussian contributions into the covariance analysis of CMB data, highlighting their impact on future experiments.

Findings

Secondary non-Gaussianities can degrade parameter estimates by up to 30%.

Current experiments are less affected by these effects.

Future high-precision measurements must account for non-Gaussian covariance.

Abstract

We consider corrections to the underlying cosmology due to secondary contributions from weak gravitational lensing, the integrated Sachs-Wolfe effect, and the Sunyaev-Zel'dovich effect contained in the trispectrum. We incorporate these additional contributions to the covariance of a binned angular power spectrum of temperature anisotropies in the analysis of current and prospective data sets. Although recent experiments such as ACBAR and CBI are not particularly sensitive to these additional non-Gaussian effects, the interpretation of Planck and CMBPol anisotropy spectra will require an accounting of non-Gaussian covariance leading to a degradation in cosmological parameter estimates by up to 20% and 30%, respectively.