1995A&A...300..335D

The growing possibility of observing the thermal and kinetic (Doppler) Sunyaev-Zel'dovich (SZ) sources and their contribution to extragalactic background fluctuations from ground-based and space experiments, scheduled for the next decade, makes it timely to predict source counts as a function of flux. We present calculations of SZ source counts for unresolved cluster of galaxies, including the Doppler effect, and predictions for millimeter and submillimeter wavelengths, not included in previous works. Calculations show that future high sensitivity experiments could observe many thermal and kinetic SZ effect sources in all-sky surveys. The measurement of the kinetic effect on hundreds of clusters could yield precious information on the large scale velocity field of the Universe. We found a mean Comptonization parameter of <y≳1.2x10^–6, compatible with the COBE limit. We also calculate the contribution of these SZ effect sources to the rms temperature fluctuations relative to the Cosmic Microwave Background and find that it cannot be neglected at small angular scales at a sensitivity level δT/T ∼ 10^–6.