Position-space description of the cosmic microwave background and its temperature correlation function.

Abstract

We suggest that the cosmic microwave background (CMB) temperature correlation function C(theta) as a function of angle provides a direct connection between experimental data and the fundamental cosmological quantities. The evolution of inhomogeneities in the prerecombination universe is studied using Green's functions in position space. We find that a primordial adiabatic point perturbation propagates as a sharp-edged spherical acoustic wave. Density singularities at its wave fronts create a feature in the CMB correlation function distinguished by a dip at theta approximately 1.2 degrees. Characteristics of the feature are sensitive to the values of cosmological parameters, in particular to the total and the baryon densities.