The new map produced by Sloan Digital Sky Survey III pinpoints the locations and distances of over a million galaxies. It covers a total volume equivalent to that of a cube four billion light-years on a side.
"We want to map the largest volume of the universe yet, and to use that map to understand how the expansion of the universe is accelerating," said Daniel Eisenstein, (Harvard-Smithsonian Center for Astrophysics), the director of Sloan Digital Sky Survey III.
With such a map, scientists can retrace the history of the universe over the last six billion years. With that history, they can get better estimates for how much of the universe is made up of dark matter- matter that we can't directly see because it doesn't emit or absorb light - and dark energy.
The map is the centerpiece of Data Release 9 (DR9), which publicly releases the data from the first two years of a six-year survey project.
The release includes images of 200 million galaxies and spectra of 1.35 million galaxies.
"Our goal is to create a catalog that will be used long after we are done," Michael Blanton, who led the team that prepared Data Release 9 said in a statement.
The ongoing SDSS-III Baryon Oscillation Spectroscopic Survey (BOSS), will measure the positions of massive galaxies up to six billion light-years away, as well as quasars - giant black holes actively feeding on stars and gas - up to 12 billion light-years from Earth.
BOSS is targeting these big, bright galaxies because they live in the same places as other galaxies and they're easy to spot. Mapping these big galaxies thus provides an effective way to make a map of the rest of the galaxies in the universe.
