Non-Gaussianity and the Cosmic Microwave Background Anisotropies

Abstract

We review in a pedagogical way the present status of the impact of non-Gaussianity (NG) on the Cosmic Microwave Background (CMB) anisotropies. We first show how to set the initial conditions at second-order for the (gauge invariant) CMB anisotropies when some primordial NG is present. However, there are many sources of NG in CMB anisotropies, beyond the primordial one, which can contaminate the primordial signal. We mainly focus on the NG generated from the post-inflationary evolution of the CMB anisotropies at second-order in perturbation theory at large and small angular scales, such as the ones generated at the recombination epoch. We show how to derive the equations to study the second-order CMB anisotropies and provide analytical computations to evaluate their contamination to primordial NG (complemented with numerical examples). We also offer a brief summary of other secondary effects. This review requires basic knowledge of the theory of cosmological perturbations at the linear level.

118 pages, 11 figures, LaTeX file. Invited Review for the special issue "Testing the Gaussianity and Statistical Isotropy of the Universe" for Advances in Astronomy

References in corpus (25)

• 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
• Gravitational Wave Spectrum Induced by Primordial Scalar Perturbations
• The cosmological gravitational wave background from primordial density perturbations
• Non-Gaussianities in Single Field Inflation and their Optimal Limits from the WMAP 5-year Data
• CMBPol Mission Concept Study: Probing Inflation with CMB Polarization
• Enhanced Non-Gaussianity from Excited Initial States
• The shape of primordial non-Gaussianity and the CMB bispectrum
• Optimal limits on f_{NL}^{local} from WMAP 5-year data
• Probing String Theory with Modulated Cosmological Fluctuations
• Constraining Running Non-Gaussianity
• Secondary anisotropies of the CMB
• CMB lensing and primordial non-Gaussianity
• Generating the Curvature Perturbation at the End of Inflation in String Theory
• Sachs-Wolfe at second order: the CMB bispectrum on large angular scales
• Impact of Secondary non-Gaussianities on the Search for Primordial Non-Gaussianity with CMB Maps
• Cosmological Perturbations at Second Order and Recombination Perturbed
• Cosmic microwave background bispectrum on small angular scales
• The impact of cosmic neutrinos on the gravitational-wave background
• Non-Gaussianity and the CMB Bispectrum: confusion between Primordial and Lensing-Rees Sciama contribution?
• Non-Gaussianity as a Probe of the Physics of the Primordial Universe and the Astrophysics of the Low Redshift Universe
• Point Source Contamination in CMB Non-Gaussianity Analyses
• Weak Lensing of the Primary CMB Bispectrum
• CMB temperature anisotropies from third order gravitational perturbations
• Impact of the 1/f noise and the asymmetric beam on non-Gaussianity searches with Planck

Cited by in corpus (57)

• Primordial Non-Gaussianities from Inflation Models
• Planck 2013 Results. XXIV. Constraints on primordial non-Gaussianity
• Resonant Non-Gaussianity
• Review of local non-Gaussianity from multi-field inflation
• Planck 2018 results. IX. Constraints on primordial non-Gaussianity
• COrE (Cosmic Origins Explorer) A White Paper
• Heavy-Lifting of Gauge Theories By Cosmic Inflation
• Implications for the non-Gaussianity of curvature perturbation from pulsar timing arrays
• A generalized local ansatz and its effect on halo bias
• Large non-Gaussianities in the Effective Field Theory Approach to Single-Field Inflation: the Bispectrum
• Large non-Gaussianities in the Effective Field Theory Approach to Single-Field Inflation: the Trispectrum
• The cosmic microwave background bispectrum from the non-linear evolution of the cosmological perturbations
• Primordial Non-Gaussianity in the Cosmic Microwave Background
• Gauge-flation Vs Chromo-Natural Inflation
• The intrinsic bispectrum of the Cosmic Microwave Background [PhD thesis]
• Non-Gaussianity in the Cosmic Microwave Background Anisotropies at Recombination in the Squeezed limit
• Insights from probability distribution functions of intensity maps
• Second-order matter perturbations in a LambdaCDM cosmology and non-Gaussianity
• Relativistic wide-angle galaxy bispectrum on the light-cone
• Unexpected Topology of the Temperature Fluctuations in the Cosmic Microwave Background
• Curvature Perturbations and non-Gaussianities from Waterfall Phase Transition during Inflation
• Impact of anisotropic stress of free-streaming particles on gravitational waves induced by cosmological density perturbations
• Impact of polarisation on the intrinsic CMB bispectrum
• Statistical Anisotropy from Vector Curvaton in D-brane Inflation
• Large Scale Anisotropic Bias from Primordial non-Gaussianity
• Computation of the Halo Mass Function Using Physical Collapse Parameters: Application to Non-Standard Cosmologies
• Local analyses of Planck maps with Minkowski Functionals
• Three and Four Point Functions of Stress Energy Tensors in D=3 for the Analysis of Cosmological Non-Gaussianities
• A Neural-Network based estimator to search for primordial non-Gaussianity in Planck CMB maps
• Forecasts on the contamination induced by unresolved point sources in primordial non-Gaussianity beyond Planck
• Impact of the free-streaming neutrinos to the second order induced gravitational waves
• Anatomy of bispectra in general single-field inflation -- modal expansions
• Reconstructing the Primary CMB Dipole
• Searching for primordial non-Gaussianity in Planck CMB maps using a combined estimator
• Evolution Equation for Non-linear Cosmological Perturbations
• Production of non-gaussianities in a bouncing phase
• Simple expressions for second order density perturbations in standard cosmology
• Second order density perturbations for dust cosmologies
• Non-Gaussianities in a two-field generalization of Natural Inflation
• Correlation of supernova redshifts with temperature fluctuations of the Cosmic Microwave Background
• Modification of the halo mass function by kurtosis associated with primordial non-Gaussianity
• Silk Damping in Scalar-Induced Gravitational Waves: A Novel Probe for New Physics
• Second order cosmological perturbations: simplified gauge change formulas
• Extension of local-type inequality for the higher order correlation functions
• Dynamics of cosmological perturbations at first and second order
• Statistical properties of polarized CMB foreground maps
• Scale-dependent Bias from the Reconstruction of Non-Gaussian Distributions
• Scalar induced gravitational waves review
• Second order cosmological perturbations: new conserved quantities and the general solution at super-horizon scale
• Impact of Instrumental Systematics on the CMB Bispectrum
• A simplified structure for the second order cosmological perturbation equations
• Diffusion of massive particles around an Abelian-Higgs string
• Principal Components of CMB non-Gaussianity
• Lecture notes on non-Gaussianity
• Phase statistics of the WMAP 7 year data
• CMB two- and three-point correlation functions from Alfvén waves
• Scalar-Induced Gravitational Waves in Palatini $f(R)$ Gravity