Conclusions


Clusters are the most massive objects in the Universe
The "mountain peaks" of the large scale structure
Ultra non-linear regime - abundance is exponentially sensitive to the cosmology
Particularly to the expansion history
If we can "inventory" the number of clusters as function of redshift and mass can constrain cosmology

SZ effect seems to be an excellent observable
Closely related to halo mass
Independent of redshift
SZ surveys are underway - expect results soon