A Molecular Hydrogen Production Model from Li and LiH in the Early Universe

Neutral isotopes and ions of H, He and Li define the chemistry of the early universe by collisional and radiative process, where under low temperature and radiation regime, only neutral species were essential in the cooling mass that gave origin to the first proto star structures. Nevertheless, up to now, in every kinetic model Li is permanently discarded from fundamental reactions due to its extremely low density. Contrarily to these previous models we have developed a novel kinetic model based on two consecutive reactions of Li and LiH with H, in order to generate a recursive process that fit well H sub(2) production to temperatures as low as 200 K, according to the cosmological time at the end of the dark epoch. Our results show how Li and LiH merge as first catalyzers of the H to H sub(2) chemical reaction and permit us to explain the expected abundance of H sub(2) as the main coolant in the early universe as well as in cold regions of the cosmos.