The Sunyaev-Zeldovich MITO project

Compton scattering of the cosmic microwave background radiation by electron s in the hot gas in clusters of galaxies the Sunyaev-Zeldovich (S-Z) effect - has long been recognized as a uniquely important feature, rich in cosmol ogical and astrophysical information. We briefly describe the effect, and e mphasize the need for detailed S-Z and X-ray measurements of nearby cluster s in order to use the effect as a precise cosmological probe. This is the g oal of the MITO project, whose first stage consisted of observations of the S-Z effect in the Coma cluster. We report the results of these observation s. (C) 2001 Elsevier Science B.V. All rights reserved.