We show that including the recoil upon scattering in the Ly-α line can lead to a noticeable acceleration of the primordial hydrogen recombination. Thus, for example, for the ΛCDM model, the decrease in the degree of ionization exceeds 1% at redshifts z = 800-1050, reaching ≈1.3% at z = 900. The corresponding corrections to the calculated cosmic microwave background power spectra reach 1.1% and 1.7% for TT and EE spectra, respectively. The radiative transfer in these calculations was treated in the quasi-stationary approximation.We have also obtained numerical solutions (in the diffusion approximation) to the nonstationary problem of radiative transfer in the Ly-α line for a partial frequency redistribution with recoil. We trace the evolution of the local line profile and the relative number of uncompensated transitions from the 2p state to the 1s state. We show that including the nonstationarity of the Ly-α line radiative transfer can lead to an additional acceleration of the primordial hydrogen recombination.

Original languageEnglish
Pages (from-to)439-444
Number of pages6
JournalAstronomy Letters
Volume34
Issue number7
DOIs
StatePublished - Jul 2008

    Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

    Research areas

  • Cosmic microwave background, Cosmology, Early Universe, Primordial hydrogen, Recombination epoch

ID: 74195306