Galaxies and the Intergalactic Medium at z=1.5-3.5

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AST-0307263SteidelThis project comprises several related observational programs to study the nature, large-scale distribution, and evolution of galaxies and of the diffuse intergalactic medium, and the relationship between the two, over the redshift range from 1.5 to 3.5, where new observational techniques and facilities are providing the first wholesale access to this almost unexplored era. The intent is to compile as complete as possible a picture of the baryonic universe during the most important era for galaxy and black hole growth. Using complementary galaxy surveys and high quality quasar absorption line spectroscopy will reveal the interactions between star-forming galaxies and intergalactic gas, and enable a study of the environment dependence of absorption systems, AGN activity, and galaxy formation and evolution. All sources of the ionizing photons that dictate the properties of the diffuse intergalactic medium will be detected and quantified. Deep optical and near-infrared spectroscopy will establish physical conditions and trends amongst the galaxy population. Some of the observed fields will be supplemented by unique information on the intergalactic medium in the same cosmic volumes, using multiple quasar lines of sight. In other fields, publicly available multi-wavelength and space-based data will be combined with the new observations to study the connection between galaxies and active galactic nuclei.The fundamental statistical information on early galaxies and the intergalactic medium obtained by this project will be useful to researchers in many sub-fields of astronomy, and all of the results and data will be made available to the community. An interest in the history of the Universe comes naturally to most people and can spark discussion between scientists and even the most science-phobic lay person. The PI's recent MacArthur fellowship provides an unusual opportunity to reach a larger audience through the resultant increased visibility, and there should be many chances to communicate the excitement of science and the scientific enterprise to nonscientists.