Constraints on the processes of non standard recombination from anisotropies of the CMB
Master Thesis manuscript (205 pages, in English), pdf available upon demand (email).
The cosmic microwave background (CMB) radiation is an excellent instrument to obtain information about the early universe and its components. It was created at recombination, when free electrons became bound into hydrogen and helium atoms, ending their interactions with photons: the universe became neutral and transparent and photons could finally propagate freely across it.
In this work I studied a model of delayed recombination by taking into account the possibility that alternative processes might have produced extra Lyman-α photons and ionizing photons and delayed the formation of neutral matter. I analysed
the effects of the introduction of these extra sources of photons with seven-year WMAP data and obtained new constraints for the delayed recombination parameters: εα <0.25 and εi < 0.0035 (95% c.l). The result of the introduction of εα is that recombination is delayed: the acoustic peaks of the power spectrum are shifted to smaller multipoles and their amplitude is reduced. The parameter εi changes the amplitude of the power spectrum peaks and the reionization peak of the polarization spectrum.
I also analyze degeneracies of the delayed recombination parameters with parameters of the cosmological model.