Cosmological hydrogen recombination: Lyn line feedback and continuum escape
Abstract
We compute the corrections to the cosmological hydrogen recombination history due to delayed feedback of Lyman-series photons and the escape in the Lyman-continuum. The former process is expected to slightly delay recombination, while the latter should allow the medium to recombine a bit faster. It is shown that the subsequent feedback of released Lyman-n photons on the lower lying Lyman-(n-1) transitions yields a maximal correction of DNe/Ne 0.22% at z~ 1050. Including only Lyman-β feedback onto the Lyman-α transition, accounts for most of the effect. We find corrections to the cosmic microwave background TT and EE power spectra with typical peak to peak amplitude |DCTTl/CTTl|~0.15% and | CEEl/CEEl|~0.36% at l<~3000. The escape in the Lyman-continuum and feedback of Lyman-α photons on the photoionization rate of the second shell lead to modifications of the ionization history which are very small (less than |DNe/Ne|~few x 10-6).
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