Cosmological Microwave Background

Abstract

A large number of theorists have been investigating the properties of inhomogeneities in the primordial universe, in particular their dynamics during the hundreds of thousands of years before decoupling. This chapter aims to explain why this dynamic is so interesting and leave such a characteristic trace in the cosmic microwave background (CMB) map, revealed by a statistical analysis of this map. To understand the anisotropies of the CMB, we need to develop a mathematical framework in order to calculate the evolution of density fluctuations in the universe. The chapter introduces the theory of cosmological perturbations. In the CMB literature, Thomson scattering is often presented as an interaction between photons and baryons. Within the framework of linear cosmological perturbation theory, any problem breaks down into two parts, the calculation of the primordial spectrum and that of transfer functions.

Authors 1

1. Julien Lesgourgues corresponding Aachen Institute for Theoretical Particle Physics and Cosmology

   RWTH Aachen University

   Affiliation as printed

   Institute for Theoretical Particle Physics and Cosmology, RWTH University, Aachen, Germany