REIONIZATION AND THE COSMIC MICROWAVE BACKGROUND IN AN OPEN UNIVERSE

If the universe was reionized at high redshift (z greater-than-or-simi lar-to 30) or never recombined, then photon-electron scattering can er ase fluctuations in the cosmic microwave background at scales greater- than-or-similar-to 1-degree. Peculiar motion at the surface of last sc attering will then have given rise to new anisotropy at the 1' level t hrough the Vishniac effect. Here the observed fluctuations in galaxy c ounts are extrapolated to high redshifts using linear theory, and the expected anisotropy is computed. The predicted level of anisotropies i s a function of OMEGA0 and the ratio of the density in ionized baryons to the critical density and is shown to depend strongly on the large- and small-scale power. It is not possible to make general statements about the viability of all reionized models based on current observati ons, but it is possible to rule our specific models for structure form ation, particularly those with high baryonic content or small-scale po wer. The induced fluctuations are shown to scale with cosmological par ameters and optical depth.