Journal
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
Volume 318, Issue 3, Pages 875-878Publisher
BLACKWELL SCIENCE LTD
DOI: 10.1046/j.1365-8711.2000.03765.x
Keywords
molecular processes; early Universe
Categories
Ask authors/readers for more resources
We study the role of HD in the thermal balance of the primordial gas, beyond the redshift, z, at which the temperatures of radiation and matter have decoupled (z approximate to 300). Statistical arguments are used to derive the rate constants for the forward and reverse reactions, D+(H-2, HD)H+, involving reactant and product molecules in excited rotational states. The degree of chemical fractionation of HD is enhanced, compared with the value calculated by taking account of reactions between ground-state molecules only, by a factor of about 2. In spite of its low abundance (10(-3)), relative to H-2, HD contributes comparably to the rate of heating of the gas, through rotationally inelastic collisions with H and He. The much larger rate coefficients for collisional population transfer within HD, compared with H-2, and the tighter rotational level spacing are responsible for this finding. We conclude that HD is about as important as H-2 in the thermal balance of the primordial gas.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available