%0 Journal Article
%T Non-equilibrium H$_2$ formation in the early Universe: energy exchanges, rate coefficients and spectral distortions
%A Carla Maria Coppola
%A Roberto D'Introno
%A Daniele Galli
%A Jonathan Tennyson
%A Savino Longo
%J Physics
%D 2012
%I arXiv
%R 10.1088/0067-0049/199/1/16
%X Energy exchange processes play a crucial role in the early Universe, affecting the thermal balance and the dynamical evolution of the primordial gas. In the present work we focus on the consequences of a non-thermal distribution of the level populations of H$_2$: first, we determine the excitation temperatures of vibrational transitions and the non-equilibrium heat transfer; second, we compare the modifications to chemical reaction rate coefficients with respect to the values obtained assuming local thermodynamic equilibrium; third, we compute the spectral distortions to the cosmic background radiation generated by the formation of H$_2$ in vibrationally excited levels. We conclude that non-equilibrium processes cannot be ignored in cosmological simulations of the evolution of baryons, although their observational signatures remain below current limits of detection. New fits to the equilibrium and non-equilibrium heat transfer functions are provided.
%U http://arxiv.org/abs/1201.1720v1