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Antoinette de Vaucouleurs Memorial Lecture Cosmic Microwave Background, Clusters of Galaxies and Cosmology Dr. Rashid Sunyaev Abstract Rich clusters of galaxies contain thousands of galaxies moving in a huge potential well with velocities exceeding 1000 km/s. They are filled with dark matter and extremely hot intergalactic gas. This gas diminishes the brightness of CMB in the directions towards clusters of galaxies opening a new way to discover distant unknown clusters. The spectrum of the brightness change is unique and does not depend on the redshift. Similarly the surface brightness of the cluster in the microwave spectral band does not depend on the redshift. This opens a way to observe the most distant clusters in the Universe, to study the key parameters of our Universe, and even to measure the peculiar velocities of clusters of galaxies in respect to the unique coordinate frame where CMB is isotropic. The Planck Surveyor Spacecraft, South Pole Telescope, Atacama Cosmology Telescope, APEX, AMI and SZ-Array observed hundreds of clusters using this method. Using the data of microwave surveys and results of the new Russian-German space project SPEKTR-X/eRosita planning to map whole sky in X-Rays we will get an opportunity to construct the "curve of growth" for clusters of galaxies and to measure the baryonic acoustic oscillations in the distribution of clusters in the relatively old Universe. The X-Ray calorimeters and hot gas observations in the lithium-like Fe57 hyperfine structure line with wavelength 3.06 mm together with broad band microwave measurements will give a unique information about about turbulence and bulk motions in the hot intercluster gas. |