Extended analysis of CMB constraints on non-Gaussianity in isocurvature perturbations

TL;DR

This paper analyzes WMAP 7-year data to constrain non-Gaussianity in isocurvature perturbations, finding consistency with Gaussian primordial fluctuations at about 2 sigma.

Contribution

It provides the first comprehensive constraints on non-Gaussianity parameters for various types of isocurvature perturbations using WMAP data.

Findings

Primordial perturbations are consistent with Gaussianity at 2 sigma

Constraints on nonlinearity parameters improve understanding of early universe

Analysis covers both correlated and uncorrelated isocurvature modes

Abstract

We study CMB constraints on non-Gaussianity from isocurvature perturbations of general types. Specifically, we study CDM/neutrino isocurvature perturbations which are uncorrelated or totally correlated with adiabatic ones. Using the data from the WMAP 7-year observation at V and W bands, we obtained optimal constraints on the nonlinearity parameters of adiabatic and isocurvature perturbations. Our result shows that primordial perturbations are consistent with Gaussian ones at around 2 sigma level for above mentioned isocurvature modes.