Cooling of Pre-Galactic Gas Clouds by Hydrogen Molecule (original) (raw)

According to the expanding hot universe model, neutralization of the cosmic plasma ceases at the stage of radiation temperature Tr::::::4000oK. After then, a density contrast in the uniform medium grows into a contracting gas cloud with mass greater than 10 5-6 M3• Hydrogen molecule is formed in the cloud after the stage of Tr:::::'300oK, and the thermal evolution is largely affected by the cooling through H 2 , whose processes are studied quantitatively in this paper. The present paper is a preliminary one for a more interesting problem of galaxy formation.