STUDIES OF DARK ENERGY WITH X-RAY OBSERVATIONS OF GALAXY CLUSTERS

This paper reviews the studies of Dark Energy using observations of galaxy clusters. There are two broad classes of observable effects of dark energy: evolution of the expansion rate of the Universe, and slow-down in the rate of growth of cosmic structures. X-ray observations of galaxy clusters has detected and characterized both of these effects. Combination of the X-ray cluster results with other cosmological datasets leads to 5% constraints on the dark energy equation-of-state parameter, and limits possible deviations of gravity on large scales from General Relativity.