Pre-galactic shocks: influence on density perturbations

The fate of spherically symmetric, homogeneous density perturbations passed by shock waves from early generations of supernovae is investigated. It is shown that a shock can only influence pre-galactic perturbations if the explosion is rather large, or if the initial density contrast is fairly low. For isothermal external or internal shocks perturbation growth may be triggered by the shock. In most other cases perturbations under influence will be heated to Jeans stability. For the most intense shocks the perturbations will subsequently evaporate. Otherwise the gas cools radiatively or by Compton cooling. Results are primarily given for an Ω = 1 Universe without non-baryonic matter, but deviations from this are discussed as well. (author)