David C. Koo
UC Observatories/Lick Observatory
David Koo’s research in observational cosmology uses large optical telescopes as time machines to peer billions of years into the past history of our universe. He is interested in exploring the creation, nature, distribution, and evolution of distant galaxies, quasars, and gas clouds. His current research relies mainly on data from the Hubble Space Telescope (HST) and the twin Keck 10-meter Telescopes in Hawaii, but his surveys also include data from other telescopes as well as observations in the X-ray, radio, and infrared wavelengths. The most ambitious project is a major, nearly completed, redshift survey of 40,000 faint galaxies using the Keck Telescope, 10,000 that have been complemented with sharp images from HST. Called DEEP (Deep Extragalactic Evolutionary Probe), this project started in year 2000, and aims to tackle many fundamental questions in the evolution of distant galaxies, the development of clustering in the universe, and the curvature of space via several cosmological tests. The survey is distinguished by its attempt to measure the masses of distant galaxies as well as their light. This is a collaborative project with astronomers from several institutions and included construction of a new powerful spectrograph for Keck. Faber, Guhathkurta, and Miller are other UCSC faculty members of DEEP. Another major research program involves participation in the NSF Science and Technology Center for Adaptive Optics awarded to UC Santa Cruz in summer of 1999 (only five awarded in the nation and the only one in the physical sciences). Adaptive optics is a technique designed to provide diffraction limited images for ground-based telescopes by correcting for the blur of the atmosphere. Such a system, already working on Keck, provides image quality sharper than that from the HST. This project is also a team effort and is also aimed towards studying the morphologies and masses of distant galaxies. Koo typically works with one or more graduate students and 3-5 postdocs at Santa Cruz. Recent work with graduate students includes exploring galaxy star formation histories from multicolor photometry; tracking the evolution of distant cluster and field galaxies; and studying the sizes and shapes of distant galaxies using the HST.