 Clusters of Galaxies: A Window to the Evolution of the Universe Principal investigator Understanding the formation and evolution of large-scale structures in the Universe has always been one of the most important goals in Astronomy. One of the cornerstones of this quest is the study of clusters of galaxies, the largest gravitationally bound structures in the Universe, and tracers of the cosmic large-scale structure. The researchers involved in this project have complementary expertise in a wide range of scientific areas. This allows them to study galaxy clusters the full electromagnetic spectrum from the radio to the x-rays, and with a large array of theoretical and observation methods. We are involved in the assembly of the XCS catalogue of galaxy clusters, witch will be the largest of its kind for many years to come. It relies on the serendipitous detection of galaxy clusters in public x-ray data from the XMM-Newton satellite (ESA), followed by confirmation using imaging and spectroscopic data acquired in the optical and near-infrared, mostly with ESO telescopes. The XCS catalogue will cover 500 square degrees of sky, a third of witch is already being analyzed, yielding thousands of galaxy clusters spanning most of the age of the Universe, up to redshifts exceeding one, and with a well known selection function. The knowledge of the evolution with time of the number density of galaxy clusters will allow us to estimate those cosmological parameters that are most important in determining the large-scale dynamics of the Universe (e.g. the density and equation of state of the dark energy). Galaxy clusters observed at different epochs in the history of the Universe will be selected for a more detailed study from the XCS catalogue. We will embark on a multi-wavelength campaign to observe these galaxy clusters so that, together with existing multi-wavelength data on already know galaxy clusters, we can determine the evolution with time of the global properties of galaxy clusters, as well as of their major constituents: dark matter; galaxies; and the intracluster medium. The nature of the interactions between these constituents, and the timescale of mergers within the present hierarchial paradigm of the process of structure formation and evolution, are important open issues witch we will address with the knowledge we will thus obtain. And by combining this knowledge with observational data probing the evolutionary history of galaxies in the field we will be able to get a better perspective on the process by witch galaxies acquire their most fundamental characteristics: morphology; stellar populations; gas content; star formation rate; nuclear activity. Although there is a maximum of 3 years of funding for this project, our research interests extend beyond this timescale, being one of our objectives to lay the groundwork to take full advantage of the research opportunities that will come forth with the launch of the Planck Surveyor satellite by ESA in 2007 and the beginning of operations of ALMA at ESO in 2008. Funding institution Start: 1 January 2005
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