SFSU Uncovers Surprises In The Stars

According to conventional wisdom, the universe's galaxies have evolved slowly over time, as stars and groups of stars collide and merge into increasingly larger groupings. But new observations by the Gemini Deep Deep Survey (GDDS) team reveal large, mature galaxies when the universe was only 3-6 billion years old, much earlier than such galaxies were believed to have existed.

Ron Marzke, SFSU assistant professor of astronomy, is a member of the eight-organization multinational GDDS team that made the discovery, which challenges the "hierarchical" or building blocks theory of galaxy evolution. The findings were announced Jan. 5 at the 203rd meeting of the American Astronomical Society, and covered by The New York Times, Space.com, USA Today and others.

The team focused on a relatively unexplored period of the universe known as the "Redshift Desert," looking back to an era just a few billion years after the Big Bang. Spectra from more than 300 galaxies were collected, and because the team used a special technique to capture the faintest galactic light ever dissected into color spectra, this is the first sampling to include not just galaxies with bright young stars, but a range of normal, dimmer and more massive galaxies.

"It gives us a much less biased picture of what was in place when the universe was 3-6 billion years old," Marzke said.

The team could efficiently focus on the most promising and representative sampling of about 300 galaxies because of an earlier survey that was processed at SFSU and the Carnegie Observatories. Marzke was a co-principal investigator of the earlier Las Campanas Infrared Survey, a detailed and time-consuming process of detecting about 100,000 galaxies. The Las Campanas survey employed a unique approach toward astronomical observation. Rather than wait for much-sought-after time on one of the largest telescopes in the field, Marzke and colleagues pooled their time on 2.5- and 4-meter telescopes, achieving "big telescope science" by using lots of time on relatively smaller telescopes. Marzke led the processing of the survey's optical data using a powerful computing center made possible by the support of SFSU's College of Science and Engineering.

Other institutions on the GDDS team are: University of Toronto, Johns Hopkins University, Carnegie Institution of Washington, Herzberg Institute of Astrophysics, Gemini Observatory, Oxford University and Massachusetts Institute of Technology. The observations were conducted using the Frederick C. Gillett Gemini North Telescope located on Mauna Kea, Hawaii.

Ligeia Polidora, 415/338-3053, ligeia@sfsu.edu