The metals in the intergalactic gas are one of our primary constraints on star formation in the early Universe, and on the processes by which forming galaxies feed back into and modify their environments, but interpretation of the metals is complex. One of the principal goals of studying intergalactic metals is to put limits on the earliest star formation, making it important to trace the metals as far back as possible. This project will obtain the highest possible signal-to-noise observations of the brightest known quasars between redshifts four and six, to determine the distributions of intergalactic ions to the deepest possible level. The new HIRES spectrograph implementation on the Keck 10-meter telescope has outstanding red sensitivity and wide wavelength coverage, providing the best available spectra for this study. Optimal analysis techniques developed under the principal investigator's previous NSF award can then be used to measure the ion densities, distributions, and ionizations at these high redshifts.
These results will have a broad impact on physical cosmology and theoretical modeling of the formation of the first stars and galaxies. Both the metallicity derivations and the spectra will be made available to theorists and to groups undertaking numerical simulations of star and galaxy formation. Research results will be spread through web pages and talks accessible to the general public. As with previous grants, graduate student support will emphasize the training of women, particularly Asian women, to assist in developing a cadre of women astronomers in these communities.
