Laboratory measurements of primordial chemistry

Abstract

Molecular hydrogen plays a key role in structure formation during the early Universe, sometimes cooling the gas and at other times heating it. We discuss three of the key chemical reactions controling the formation of H 2 during the epoch of primordial galaxy and first star formation. These are the associative detachment (AD) reaction H − + H → H 2 + e − , the mutual neutral (MN) reaction H − + H + → H + H, and the three body association (TBA) process H + H + H → H 2 + H. For each reaction we discuss the cosmological implications due to uncertainties in the relevant rate coefficients. In the case of AD we also present our recent experimental work to remove these uncertainties. For MN we discuss our ongoing experimental work. Lastly, for TBA we discuss the theoretical and experimental challenges facing attempts to improve the required reaction data.

Laboratory studies of primordial chemistry and implications for first star formation

“…Uncertainties in the rate coefficients for all three of these reactions have limited our understanding of structure formation in the early Universe. In Savin [1], we present recent measurements which largely remove the uncertainties for the AD and MN reactions. There, we also discuss the experimental challenges of attempting to measure the TBA reaction.…”