Dark energy contraints from growth of structure: results from the 400 deg^2 X-ray cluster survey.

Alexey Vikhlinin, SAO

Observations of the evolving cluster mass function provide a sensitive cosmological test which internally combines the geometry and growth of structure components. If cluster masses can be measured reliably from observables, the statistical power of this test is comparable to that from a similar number of high-z SN Ia. I will discuss the issues which have to be solved in working with the current-generation experiments and present results from a 400 square degrees X-ray survey.