9315368 Bahcall This research will support work in cosmology, large-scale structure, and clusters of galaxies. The goal of the research is the determination of the structure in the universe and the discrimination among various cosmological models. They will perform analyses of observational data, and use some of the largest cosmological model simulations available to date to address the following topics: (1) Investigate the large-scale structure in the universe using galaxy clusters, superclusters, quasars, radio galaxies, and pencil-beam surveys as tracers, and integrate the results into a unified picture; (2) Use large-scale computer simulations of cosmological models to compare the observations with predictions from different models; and, (3) Study the detailed properties--in optical, X-ray, and optical-to-X-ray cross-correlations of clusters of galaxies, the largest bound systems known. Implications regarding the cluster potential and dark-matter distribution, galaxy and hot gas distribution, velocity bias, and the nature of the intracluster medium will be derived and compared with cosmological simulations. The observational analysis and modeling will clarify the nature of galaxy clusters and of larger scale structure and constrain cosmological models. The Principal Investigator and her collaborators have successfully worked in these fields and are regarded as highly experienced in these research areas. ***
