Cosmic microwave background anisotropies induced by global scalar fields: The largeNlimit

We present an analysis of cosmic microwave background (CMB) anisotropies induced by global scalar fields in the large $N$ limit. In this limit, the CMB anisotropy spectrum can be determined without cumbersome 3D simulations. We determine the source functions and their unequal time correlation functions and show that they are quite similar to the corresponding functions in the texture model. This leads us to the conclusion that the large $N$ limit provides a “cheap approximation” to the texture model of structure formation.