The Sunyaev–Zeldovich Effect: Recent Work

Scattering of the cosmic microwave background (CMB) radiation by hot gas in clusters of galaxies produces a unique spectral signature – the Sunyaev–Zeldovich (S–Z) effect – that constitutes an important cosmological probe. The effect has been sensitively measured in more than 40 clusters, mostly with ground-based interferometric arrays operating at low microwave frequencies. These measurements have already yielded important information on cluster masses, and the Hubble constant. The scientific yield will be greatly increased when spectral and high-resolution spatial measurements of the effect in a large sample of nearby clusters will be made with stratospheric telescopes equipped with bolometric arrays. I review the current status of observational and theoretical S–Z work, and describe the main goals and challenges of using the effect as a more precise probe of cluster properties and cosmological parameters.