This project will use a specially-targeted sample of luminous early-type galaxies in the Sloan Digital Sky Survey (SDSS) to probe the large-scale correlations of galaxies with unprecedented accuracy. This will refine existing measurements of the baryon acoustic oscillations (BAO) and the matter density of the Universe. Sound waves that propagate in the first million years after the Big Bang imprint distinctive features into the anisotropies of the cosmic microwave background (CMB) and the clustering of matter today. These BAO create a sharp feature in the correlation of galaxies whose scale can be combined with information from CMB anisotropy data to place strong constraints on the curvature of the Universe and on dark energy. The SDSS Luminous Red Galaxy (LRG) sample is the best dataset by a wide margin for studying the BAO and other aspects of large-scale structure. Coupling these data with new theoretical insights should lead to significant improvements, perhaps halving the error bars on earlier results.
The acceleration of the expansion rate of the Universe is one of the central problems in modern cosmology and poses a deep challenge to physics. Both the observational and the theoretical parts of this work will have a direct impact on the design of future galaxy redshift surveys, and on the portfolio of dark energy experiments. The principal investigator will also continue to engage several students, both graduate and undergraduate, in this research.
