Rapid HeII->HeI recombination and radiation concerned with this process

Abstract

Recombination of the primordial helium plasma (HeII->HeI, $z\simeq 1500-3000$) is considered. This process has an effect on the CMBR anisotropy and CMBR spectrum distortion. In this work an influence of neutral hydrogen on kinetics of HeII->HeI recombination is investigated in the frame of the standard cosmological model. It is shown that small amount of neutral hydrogen ($10^{-5}-10^{-2}$ of total number of hydrogen ions and atoms) leads to acceleration of HeII->HeI recombination at $z\lesssim 2000$ and at $z\lesssim 1600$ quasi-equilibrium HeII->HeI recombination (according to the Saha formula) becomes valid.

submitted to MNRAS Letters 23.01.2007, accepted 15.03.2007, 5 pages, 5 figures, 1 table

References in corpus (4)

• Lines in the Cosmic Microwave Background Spectrum from the Epoch of Cosmological Hydrogen Recombination
• The effect of forbidden transitions on cosmological hydrogen and helium recombination
• Two-Photon 2s<->1s Transitions during Recombination of Hydrogen in the Universe
• Perturbations of ionization fractions at the cosmological recombination epoch

Cited by in corpus (7)

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• Is there a need and another way to measure the Cosmic Microwave Background temperature more accurately?
• Uncertainties in Theoretical HeI Emissivities: HII Regions, Primordial Abundance, and Cosmological Recombination
• Time-Dependent Corrections to the Ly-alpha Escape Probability During Cosmological Hydrogen Recombination
• WMAP 5-year constraints on time variation of $\alpha$ and $m_e$ in a detailed recombination scenario