LOOKING FOR A COSMOLOGICAL CONSTANT WITH THE REES-SCIAMA EFFECT

In models with a cosmological constant a significant component of the cosmic microwave background (CMB) anisotropy is produced at rather low redshifts z less than or similar to 1. In these models, the gravitati onal potential perturbations begin to evolve at late times, shifting t he frequencies of photons passing though them. Since the potential ref lects the matter density, the latter should be correlated with the CMB anisotropy. We examine this correlation and discuss the prospects for using an x-ray/COBE comparison to detect a cosmological constant.