Influence of a quasi-molecular mechanism of recombination on the formation of hydrogen in the early Universe

Abstract

ABSTRACT In the framework of a quasi-molecular approach, the formation of hydrogen atom in the pre-recombination period of evolution of the Universe is analysed quantitatively. Calculations in an adiabatic multilevel representation enable estimates of probabilities of radiative transitions. The quasi-molecular mechanism of recombination allows the formation of hydrogen molecular ion, ${\mathrm{ H}_2}^+$, in its ground state. The probability of this process is comparable with the probability of the creation of atomic hydrogen. The participation of a second proton in the recombination increases the binding energy of an electron and decreases the rate of recombination of hydrogen.