The Lithium Chemistry of the Early Universe

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Session 55 -- Early Universe
Display presentation, Tuesday, 10, 1995, 9:20am - 6:30pm

[55.01] The Lithium Chemistry of the Early Universe

P. C. Stancil, S. Lepp (UNLV), A. Dalgarno, K. Kirby (CfA)

Calculations will be presented for the abundances of Li, Li$^+$, LiH, and LiH$^+$ during the post recombination epoch of the early universe. Atomic lithium is found to remain significantly ionized with a fractional ionization $f\sim$ 0.5 to redshifts $z$ as small as 10. The abundance of LiH is determined to be $\sim 10^2$ smaller than obtained by previous calculations due to the inclusion of a new quantal radiative association rate coefficient. Inclusion of other gas-phase reactions further reduces the LiH abundance. LiH$^+$ is found to be less abundant than LiH. These low abundances suggest that Thomson scattering between cosmic background radiation (CBR) photons and primordial LiH and LiH$^+$ plays an insignificant role in erasing CBR anisotropies. Though the densities will increase in collapsing proto-clouds, the initially small abundances may severely limit searches for highly redshifted rovibrational lines and reduce their utility for constraining the cosmological Li abundance. The new LiH and LiH$^+$ radiative association rate coefficients will also be presented.

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