Molecular fluorine chemistry in the early Universe

¹ Université des Sciences Montpellier II, Groupe de Recherche en Astronomie et Astrophysique du Languedoc, GRAAL CC72, 34095 Montpellier, France e-mail: Denis.Puy@graal.univ-montp2.fr
² SPb Branch of Special Astrophysical Observatory, RAS, St Petersburg, Russia
³ Centro de Investigación en Física, UNISON, Rosales y Blvd. Transversal, Col. Centro, Edif. 3-I, Hermosillo, Sonora, 83000 Mexico, México

Received: 14 December 2006
Accepted: 15 August 2007

Abstract

Context.Some models of Big Bang nucleosynthesis suggest that very high baryon density regions were formed in the early Universe, and generated the production of heavy elements other than lithium such as fluorine F.

Aims.We present a comprehensive chemistry of fluorine in the post-recombination epoch.

Methods.Calculation of F, F^- and HF abundances, as a function of redshift z, are carried out.

Results.The main result is that the chemical conditions in the early Universe can lead to the formation of HF. The final abundance of the diatomic molecule HF is predicted to be close to when the initial abundance of neutral fluorine F is 10^-15.

Conclusions. These results indicate that molecules of fluorine HF were already present during the dark age. This could have implications on the evolution of proto-objects and on the anisotropies of cosmic microwave background radiation. Hydride of fluorine HF may affect enhancement of the emission line intensity from the proto-objects and could produce spectral-spatial fluctuations.