On the relative abundance of LiH and LiH+ molecules in the early universe: new results from quantum reactions

TL;DR

This paper uses accurate quantum calculations to reassess the chemical pathways affecting LiH and LiH+ molecules in the early universe, revealing higher LiH abundances than previously estimated across relevant redshifts.

Contribution

It provides new quantum reaction rates that revise the predicted relative abundances of LiH and LiH+ in the early universe, improving understanding of primordial molecular chemistry.

Findings

LiH abundances are higher than LiH+ at all redshifts.

Significant differences from previous calculations in molecular abundance predictions.

Enhanced understanding of molecular cooling processes in early universe conditions.

Abstract

The relative efficiencies of the chemical pathways that can lead to the destruction of LiH and LiH+ molecules, conjectured to be present in the primordial gas and to control molecular cooling processes in the gravitational collapse of the post-recombination era, are revisited by using accurate quantum calculations for the several reactions involved. The new rates are employed to survey the behavior of the relative abundance of these molecules at redshifts of interest for early universe conditions. We find significant differences with respect to previous calculations, the present ones yielding LIH abundances higher than LiH+ at all redshifts.