SDSS-III 3-D Map of Massive Galaxies, Distant Black Holes Offers Clues to Dark Matter and Energy

The Sloan Digital Sky Survey III (SDSS-III) has released the largest-ever three-dimensional map of massive galaxies and distant black holes, helping astronomers better explain the mysterious “dark matter” and “dark energy” that make up 96 percent of the universe. According to SDSS-III scientific spokesperson and University of Pittsburgh assistant professor of physics and astronomy Michael Wood-Vasey, scientists using the map—titled Data Release 9 (DR9)—can retrace the Universe’s history over the last seven billion years. Wood-Vasey cowrote the DR9 summary paper featured on the arXiv database.

“This is science at its collaborative best,” said Wood-Vasey. “SDSS-III scientists work together to address big questions extending from our own galaxy to distant reaches of the Universe, and then they share that data with the world to allow anyone to make the next big discovery.”

The new DR9 map of the Universe includes images of 200 million galaxies and spectra measurements of how much light galaxies gives off at different wavelengths—of 1.35 million galaxies, including new spectra of 540,000 galaxies dating from when the universe was half its present age. Researchers at SDSS-III say that studying spectra is important because it allows scientists to figure out how much the Universe has expanded since the light left each galaxy.

Additionally, having this new data to analyze not only helps researchers understand the distant Universe, but also the Earth’s own cosmic backyard—the Milky Way Galaxy. DR9 includes better estimates regarding the temperatures and chemical compositions of more than a half million stars in the Milky Way.

DR9 represents the latest in a series of data releases stretching back to 2001. This release includes new data from the ongoing SDSS-III Baryon Oscillation Spectroscopic Survey (BOSS), which will eventually measure the positions of 1.5 million massive galaxies over the past seven billion years of cosmic time, as well as 160,000 quasars—giant black holes feeding on stars and gas—from as long ago as 12 billion years.

While all of these new images and spectra contain the promise of new discoveries about the universe, SDSS-III is only in the middle of its six-year survey and will release three times as much data by the time it has completed its work, in 2014.

All the newly released data is now available on the DR9 Web site, at www.sdss3.org/dr9. Additionally, the SkyServer Web site (http://skyserver.sdss3.org) includes lesson plans for teachers who use DR9 data to teach astronomy and other topics in science, technology, and mathematics.