Sunyaev-Zeldovich effects, free-free emission, and imprints on the cosmic microwave background

The signatures from Sunyaev-Zeldovich effects and free-free emission in the intergalactic and intracluster medium and at galactic scales probe the structure evolution at various cosmic times. The detection of these sources and, possibly, the precise imaging of their spatial structure at the high resolution and sensitivity achievable with SKA will greatly contribute to the comprehension of crucial cosmological and astrophysical aspects, as the physical conditions of early ionized halos, quasars and proto-galactic gas and the mapping of the thermal and density structure of clusters of galaxies, with an extremely accurate control of extragalactic radio sources, which represents also a useful by-product for future cosmic microwave background spectrum experiments devoted to probe the thermal plasma history at early times. (C) 2004 Elsevier B.V. All rights reserved.