Collaborative Research: Addressing the Burning Questions in the Baryon Cycle at z~2

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Astronomers want to understand how galaxies grow. In particular they want to know why the rate of star formation was highest when the Universe was young. Shapley, Reddy, and Steidel will analyze observations of thousands of distant galaxies obtained with the Keck Telescopes. They will investigate how material flowing into and out of a galaxy can affect the rate of star formation and other key galaxy properties. In partnership with the WorldWide Telescope Ambassadors Program the PIs will develop interactive tours across the night sky. One tour will demonstrate how telescopes act as time machines. Local high school students and their teachers will be invited to participate in a Summer Research Connection program at Caltech. The PI and her team will train the students to be future scientists.Shapley, Reddy, and Steidel have identified a representative sample of galaxies at the epoch of peak star formation in the universe (z~1.5-3.5) in the Keck Baryonic Structure Survey (KBSS) and the MOSFIRE Deep Evolution Field (MOSDEF) Survey. A subset of ~20% also have deep Keck/LRIS rest-UV spectra, and ~100 galaxies have integral- field unit maps from the Keck KCWI instrument. The co-PIs will establish robust metallicity measurements of gas and stars within galaxies at this epoch; they will determine the kinematics and geometry of gas outflow and inflow based on "down the barrel" galaxy spectroscopy; they will map the gas distribution and kinematics in the more extended circumgalactic medium (CGM), connecting the CGM-scale properties with those on the galaxy scale. Collectively, these results will test and inform forefront models of baryonic cycling in galaxy evolution. A legacy dataset consisting of the reduced Keck MOSFIRE, LRIS, and KCWI spectroscopic data will be available in a public archive.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.