Generation of Microwave Background Fluctuations from Nonlinear Perturbations at the ERA of Galaxy Formation

The production of temperature distortions of the microwave background by primordial galaxy formation is investigated theoretically. The temperature anisotropies induced by the presence of hot ionized gas during the formation of structure are roughly approximated and found to be greater than the initial anisotropies predicted by hierarchical models, and close to the present upper limit (delta (T/T = about 0.00001 at angular scale 1 arcmin) for standard cold-dark-matter models with Omega(0) = Omega(b) = H/(100 km/s) = 1. It is suggested that sensitive small-scale microwave-fluctuation measurements can impose significant constraints on models of primordial galaxy formation.