The positive feedback of population III objects on galaxy formation

We study the formation of molecular hydrogen in cooling gas behind shocks produced during the blow-away process thought to occur in the first collapsed, luminous (Population III) objects in the early universe. We find that for a wide range of physical parameters, the H-2 fraction is f approximate to 6 x 10(-3). The H, mass produced in such explosions can exceed the amount of relic H-2 destroyed inside the photodissociation region surrounding a given Population III object. We conclude, differently from the suggestion of Haiman et al., that these first objects might have a net positive feedback on subsequent galactic formation. We discuss the effects of radiation and the implications of our results for the soft-UV background.