Vibrational level population of H2 and H+2 in the early universe

Abstract

We formulate vibrationally resolved kinetics for molecular hydrogen and its cation in the primordial universe chemistry. Formation, destruction, and relaxation processes for each vibrational level are studied and included as chemical pathways of the present model. The fractional abundance of each vibrational level as a function of the redshift is given: a strong deviation from the Boltzmann distribution is found at low z. A discussion of the results is provided, also evaluating the effects of relaxation processes on the level populations. Analytical fits for some local thermal equilibrium rate coefficients are given in the Appendix. © 2011. The American Astronomical Society. All rights reserved.