The red-sequence cluster survey: cosmology and galaxy cluster evolution

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The discovery that that the universe is accelerating forced astronomers to hypothesize the existence of dark energy.  Understanding dark energy, the most dominant and least understood component of the universe, is the single most important goal in modern cosmology.  A first step in this direction is to measure the equation of state (the ratio between the pressure and density of this mysterious component), encapsulated by the parameter w. Dark energy produces subtle effects on geometry of the universe and the rate of growth of structures such as galaxies and cluster of galaxies.  Several observational experiments are underway, e.g., using the distance of supernovae, to attempt to measure w.  This is proposal to image a large area on the sky (1000 sq. deg) to use the number of rich galaxy clusters, the most massive structure in the universe, to derive w.  The observation will be done using the large mosaic CCD camera on the Canada-France-Hawaii Telescope.  The 1000 sq. deg. of images will provide data on ~100 million galaxies, from which about 30000 galaxy clusters will be discovered.  The project will also carry out extensive follow-up observational programs to estimate the mass of clusters in order to derive the mass function of the clusters.  By estimating the number of clusters and their masses during different epochs in the universe, we will be able to constrain various cosmological parameters, including w.  These follow-up programs will also allow us to study the formation and evolution of galaxy clusters.