Cosmic Microwave Background temperature and polarization anisotropies
  from the large-N limit of global defects
  We determine the full C_l spectra and correlation functions of the
temperature and polarization anisotropies in the CMB, generated by a source
modeled by the large N limit of spontaneously broken global O(N)-theories. We
point out a problem in the standard approach of treating the radiation-matter
transition by interpolating the eigenvectors of the unequal-time correlators of
the source energy-momentum tensor. This affects the CMB predictions from all
type of cosmic defects. We propose a method to overcome this difficulty, and
find that in the large-N global model that we study, differences in the final
CMB power spectra amplitudes reach up to 25%, when compared to implementations
of the eigenvector interpolation technique. We discuss as well how to optimally
search for the contribution in the CMB from active sources such as cosmic
defects, in experiments like Planck, COrE and PRISM.
