Xth School of Cosmology
  5 -10 July 2010 at IESC, Cargèse
 The Cosmic Microwave Background at High Angular Resolution

Hunting for Primordial non-Gaussianity in the Cosmic Microwave Background

Eiichiroo KOMATSU
Department of Astronomy, The University of Texas at Austin

Course Chapters
  1. Basics of Gaussian and non-Gaussian statistics
  2. Effects of non-Gaussianity on cosmological fluctuations
  3. Measuring non-Gaussianity from the cosmological data
Abstract   
Since the first limit on the (local) primordial non-Gaussianity parameter, fNL, was obtained from COBE data in 2002, observations of the CMB have been playing a central role in constraining the amplitudes of various forms of non-Gaussianity in primordial fluctuations. The current 68% limit from the 7-year WMAP data is fNL=32+/-21, and the Planck satellite is expected to reduce the uncertainty by a factor of four in a few years from now. If fNL>>1 is found by Planck with high statistical significance, all single-field models of inflation would be ruled out. Moreover, if the Planck satellite finds fNL=30, then it would be able to test a broad class of multi-field models using the four-point function (trispectrum) test of tauNL>=(6fNL/5)^2. In this lecture, we review the basics of Gaussian and non-Gaussian statistics, learn the significance (why bispectrum and trispectrum), methods (optimal estimator), results (WMAP 7-year), and challenges (secondary anisotropy, second-order effect, and foreground) of measuring primordial non-Gaussianity from the CMB data.
Bibliography
  • Hunting for Primordial non-Gaussianity in the Cosmic Microwave Background
    Eiichiro Komatsu, Classical and Quantum Gravity, 27, 124010 (2010); arXiv:1003.6097
    and references therein.

Program