Rapid HeII->HeI recombination and radiation concerned with this process
Abstract
Recombination of the primordial helium plasma (HeII->HeI, z 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 2000 and at z 1600 quasi-equilibrium HeII->HeI recombination (according to the Saha formula) becomes valid.
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