CMB Anisotropies at Second-Order II: Analytical Approach
  We provide an analytical approach to the second-order Cosmic Microwave Background (CMB) anisotropies generated by the non-linear dynamics taking place at last scattering. We study the acoustic oscillations of the photon-baryon fluid in the tight coupling limit and we extend at second-order the Meszaros effect. We allow for a generic set of initial conditions due to primordial non-Gaussianity and we compute all the additional contributions arising at recombination. Our results are useful to provide the full second-order radiation transfer function at all scales necessary for establishing the level of non-Gaussianity in the CMB. 
Nicola Bartolo (ICTP Trieste and Physics Department Padova, Italy),   Sabino Matarrese (Physics Department Padova, Italy) an...