Chemical Abundances in the Intergalactic Medium: Evolution and Constraints on Feedback From Galaxy Formation

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Dr. Simcoe will use instruments on the Magellan telescopes in Chile to study the buildup of carbon and oxygen in the intergalactic gas early in cosmic history, before and during the period when the galaxies made most of their stars. These 'heavy' chemical elements are produced inside stars, and released into interstellar gas as the stars die. In young galaxies, both their active nuclei and violent starbirth can eject heavy-element-rich gas into intergalactic space. Thus the amount of carbon and oxygen in the intergalactic gas traces the formation of the galaxies. The strongest spectral lines of highly-ionized carbon and oxygen are in the ultraviolet. But in the spectra of distant quasars, cosmic expansion means that we observe these lines at wavelengths longer by the redshift factor 1+z, so they are seen at visible or even infrared wavelengths. Dr. Simcoe will take high-quality optical spectra to derive carbon and oxygen abundances for gas that lies between us and luminous quasars in the redshift range 2.5z4.5. Studies of the 14 known quasars with z5.8 that are accessible from the Southern-hemisphere Magellan telescopes will be a first science project for the FIRE infrared spectrograph, which Dr. Simcoe has built under an earlier NSF grant. FIRE should be ready to go to the telescope in late 2009. A graduate student will be trained by working on this project. Dr. Simcoe will continue to train undergraduate students through MIT's UROP program; he has already mentored five students through this program, four of whom were members of groups under-represented in the physical sciences. During this early science project with FIRE, Dr. Simcoe and his team will optimize the reduction and analysis tools, and make them available to the Magellan user community.