Large-Scale Structure in the Local Universe

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Studies of large-scale structure of the universe are providing, at the present time, the strongest constraints on models of the early universe. There is good evidence for complex structure on the scale of 30 to 60 million light years that may be compatible with current models, however, the larger 150 to 300 million light year structures, still controversial, pose a much greater difficulty. A chief ambiguity in interpretation is that galaxy distributions may present a biased mapping of the distribution of mass. However, velocity mapping - measuring deviations from a smooth Hubble flow - makes it possible to infer all the mass and allows simple comparison with theory and model simulations. Three programs that follow from the mapping of the local Hubble flow with elliptical galaxies will be carried out. The original study found a large-scale flow pattern pointing toward the intersection of the galactic and supergalactic planes. One of the programs is a redshift survey to map the "Great Attractor", an enormous overdensity in the galaxy distribution that may be responsible for the flow pattern. The second program is to carry out more measurements of deviations from pure Hubble flow in this direction by finding distances to elliptical and spherical galaxies using a distance relation and by infering distances to spiral galaxies with the (optical) Tully-Fisher relation. The third program is a further investigation of the suitability of the distance relation to measurement of the Hubble constant. The Hubble constant provides a relation between the redshift and the distance of a galaxy.