Adiabatic versus Isocurvature Non--Gaussianity

Abstract

We study the extent to which one can distinguish primordial non--Gaussianity (NG) arising from adiabatic and isocurvature perturbations. We make a joint analysis of different NG models based on various inflationary scenarios: local-type and equilateral-type NG from adiabatic perturbations and local-type and quadratic-type NG from isocurvature perturbations together with a foreground contamination by point sources. We separate the Fisher information of the bispectrum of CMB temperature and polarization maps by l for the skew spectrum estimator introduced by Munshi & Heavens (2009) to study the scale dependence of the signal-to-noise ratio of different NG components and their correlations. We find that the adiabatic and the isocurvature modes are strongly correlated, though the phase difference of acoustic oscillations helps to distinguish them. The correlation between local-and equilateral-type is weak, but the two isocurvature modes are too strongly correlated to be discriminated. Point source contamination, to the extent to which it can be regarded as white noise, can be almost completely separated from the primordial components for l>100. Including correlations among the different components, we find that the errors of the NG parameters increase by 20-30% for the WMAP 5-year observation, but 5% for Planck observations.

7 pages, 3 figures

References in corpus (15)

• Five-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Cosmological Interpretation
• Five-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Likelihoods and Parameters from the WMAP data
• Detection of primordial non-Gaussianity (fNL) in the WMAP 3-year data at above 99.5% confidence
• Optimal limits on f_{NL}^{local} from WMAP 5-year data
• Fast Estimator of Primordial Non-Gaussianity from Temperature and Polarization Anisotropies in the Cosmic Microwave Background
• Constraining Isocurvature Initial Conditions with WMAP 3-year data
• Non-Gaussianities from ekpyrotic collapse with multiple fields
• A New Approach to Probing Primordial Non-Gaussianity
• On the Initial Conditions in New Ekpyrotic Cosmology
• Isocurvature, non-gaussianity and the curvaton model
• Limits on Isocurvature Perturbations from Non-Gaussianity in WMAP Temperature Anisotropies
• Non-Gaussianity and Baryonic Isocurvature Fluctuations in the Curvaton Scenario
• Non-Gaussianity from Symmetry
• Non-Gaussianity from Baryon Asymmetry
• Right-handed neutrinos as the source of density perturbations

Cited by in corpus (10)

• Review of local non-Gaussianity from multi-field inflation
• CMB constraint on non-Gaussianity in isocurvature perturbations
• Primordial Non-Gaussianity in Models with Dark Matter Isocurvature Fluctuations
• Isocurvature perturbations in extra radiation
• Non-Gaussian isocurvature perturbations in dark radiation
• Primordial Non-Gaussianity from a Joint Analysis of Cosmic Microwave Background Temperature and Polarization
• Extended analysis of CMB constraints on non-Gaussianity in isocurvature perturbations
• Natural Hybrid Inflation Model with Large Non-Gaussianity
• Principal Components of CMB non-Gaussianity
• Smooth hybrid inflation in a supersymmetric axion model