  In the standard galaxy formation scenario plasma clouds with a high thermal
energy content must exist at high redshifts since the proto-galactic gas is
shock heated to the virial temperature, and extensive cooling, leading to
efficient star formation, must await the collapse of massive halos (as
indicated by the massive body of evidence, referred to as "downsizing").
Massive plasma clouds are potentially observable through the thermal and
kinetic Sunyaev-Zel'dovich effects and their free-free emission. We find that
the detection of substantial numbers of galaxy-scale thermal SZ signals is
achievable by blind surveys with next generation radio telescope arrays such as
EVLA, ALMA and SKA. This population is even detectable with the 10% SKA, and
wide field of view options at high frequency on any of these arrays would
greatly increase survey speed. An analysis of confusion effects and of the
contamination by radio and dust emissions shows that the optimal frequencies
are those in the range 10-35 GHz. Predictions for the redshift distributions of
detected sources are also worked out.
