title: Cosmic microwave background bispectrum from recombination.
abstract: We compute the cosmic microwave background temperature bispectrum generated by nonlinearities at recombination on all scales. We use CosmoLib2nd, a numerical Boltzmann code at second order to compute cosmic microwave background bispectra on the full sky. We consistently include all effects except gravitational lensing, which can be added to our result using standard methods. The bispectrum is peaked on squeezed triangles and agrees with the analytic approximation in the squeezed limit at the few percent level for all the scales where this is applicable. On smaller scales, we recover previous results on perturbed recombination. For cosmic-variance limited data to l(max)=2000, its signal-to-noise ratio is S/N=0.47, corresponding to f(NL)(eff)=-2.79, and will bias a local signal by f(NL)(loc) ~/= 0.82.
authors.affiliation: CEA, Institut de Physique Théorique, F-91191 Gif-sur-Yvette cédex, France, CNRS, Unité de recherche associée-2306, F-91191 Gif-sur-Yvette cédex, France.
authors.forename: Zhiqi
authors.initials: Z
authors.lastname: Huang
authors.forename: Filippo
authors.initials: F
authors.lastname: Vernizzi