This project extends recent work by the PI and collaborator on the nature and spatial extent of dust around galaxies at cosmological distances. The team, by correlating the colors of quasars with the density of foreground galaxies, has established that these galaxies (on average) have dust halos extending out to on the order of 10 megaparsecs. In this project they will greatly increase the depth and wavelength coverage of the analysis, applying their existing techniques and making use of the newest archival data releases from the Sloan Digital Sky Survey, Deep Lens Survey, and the deep sample of the Canada-France-Hawaii Telescope Legacy Survey (optical), the GALEX satellite (ultraviolet), and the FIRST survey (radio). They will study the dependence of the dust extent and absorption properties on galaxy luminosity, morphological type, and redshift; constrain the physical nature of the dust and possible scenarios for the enrichment of galaxy halos; and assess the impact that extended dust will have on future measurements of the expansion and acceleration of the universe. A software package developed by the PI for analyzing multiwavelength data from disparate sources (STOMP) will be made available to the community. The PI, as one of the developers of Google Sky, will explore the development of an "astronomical wiki," through which research results can be shared with the community and the public. A graduate student will be trained through participation in the research.
