M. Kunz et R. Durrer, COSMIC MICROWAVE BACKGROUND ANISOTROPIES INDUCED BY GLOBAL SCALAR FIELDS - THE LARGE N-LIMIT, Physical review. D. Particles and fields, 55(8), 1997, pp. 4516-4520
We present an analysis of cosmic microwave background (CMB) anisotropi
es 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 corr
esponding functions in the texture model. This leads us to the conclus
ion that the large N limit provides a ''cheap approximation'' to the t
exture model of structure formation.