 The Universe on the Large Scale: A New Observational Era Principal investigator The understanding of the large-scale behavior of the Universe has always been one of the most important objectives in Astronomy, being essential to the determination of the ultimate fate of the Universe. We would like to continue contributing to this log running quest by using our expertise in the estimation of those cosmological parameters that are most important in determining the large-scale dynamics of the Universe (e.g. the densities and equations of state of the differents types of dark matter and energy), as well as the structure formation process (e.g. the nature of the primordial density perturbations). New observational data will become available in the next two years, that will allow the estimation of these parameters with unprecedented accuracy. We are at the forefront of this challenge by being involved in some of the projects that will yield such data: the XCS serendipitous galaxy cluster survey, which uses the XMM-Newton satellite (ESA) and ground-based optical facilities like the VLT (ESO) and Keck observatories, and will allow the determination of the evolution with time of the galaxy cluster abundance; and the VSA interferometer, which will extend the accurate measurement of the amplitude of the temperature anisotropies in the cosmic microwave background radiation (CMBR) to very small scales. Other important observational data that will also become available in the next couple of years and which we plan to use in our work are: the very detailed measurement via the MAP satellite of the spectrum of temperature anisotropies in the CMBR; and the extension to higher redshifts of the Supernova type Ia magnitude-distance relation. Moreover, we expect to become involved in the preparation of 2 important future satellite missions: Planck Surveyor (ESA) and SNAP (NASA). Regarding the first, we are already in the midst of developing new analytical tools to search for possible non-gaussian primordial features in CMBR anisotropy maps, suited even for the very small scales that Planck Surveyor will probe. While, in the case of SNAP, we will be proposing the use of our XCS survey, in conjunction with both optical and sub-millimeter galaxy cluster data, to identify the best target areas in the sky for the search of supernovae type Ia. Our work will rely heavily on computer simulation software, most of it already available, but which on some instances will have to be further developed by us. We will use it for generating mock XCS catalogues of galaxy clusters, under the assumption of different values for cosmological parameters, and which we will attempt to mimick the in-flight instrumental performance of XMM-Newton. We will also use simulation software to produce maps of temperature anisotropies in the CMBR, taking into account all possible sources of such anisotropies, including those induced by our own Galaxy. Finally, we plan to improve the limits we have already been able to impose on general large-scale properties of the universe, like its degree of anisotropy and its topology, and on the possible variation with time of some fundamental physical quantities, like the fine structure parameter or the velocity of light. In order to do this, we will make use not only of some the observational data previously mentioned, but also of high signal-to-noise quasar spectra, which we will attempt to obtain though the VLT. Funding institution Start: 1 May 2002
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