The Sunyaev-Zeldovich Effect as Microwave Foreground and Probe of Cosmology

The Sunyaev-Zel'dovich (SZ) effect from clusters of galaxies should yield a significant signal in cosmic microwave background(CMB) experiments at small angular scales ($\ell \ga 1000$). Experiments with sufficient frequency coverage should be able to remove much of this signal in order to recover the primary anisotropy. The SZ signal is interesting in its own right; the amplitude and angular dependence are sensitive to both cosmology and the evolution of the gas. Combining CMB measurements with planned non-targeted SZ surveys could isolate the cosmological effects, providing CMB experiments with a low-redshift test of cosmology as a consistency check. Improvements in the determination of the angular diameter distance as a function of redshift from SZ and X-ray observations of a large sample of clusters will also provide a probe of cosmology.