Penn Scientists Create 3D map of Dark Matter and Dark Energy

The largest ever three dimensional map of massive galaxies and distant black holes produced by Sloan digital Sky Survey III (SDSS III), helps in investigating the mysterious "dark matter" and "dark energy" that make up 96 percent of the universe.

Prior to this new creation SDSS III had created the largest-ever image of the sky, which covered one-third of the night sky.  The new data "Data Release 9" (DR9) releases the data from the first two years of this six-year project.

"What really makes me proud of this survey is our commitment to creating a legacy for the future," said Michael Blanton, a New York University physics professor who led the team that prepared DR9. "Our goal is to create a map of the universe that will be used long after we are done, by future generations of astronomers, physicists, and the general public."

DR9 is 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 actively feeding on stars and gas from as long ago as 12 billion years in the past.

The reason why these big bright stars are a target of BOSS is because they are found along with other galaxies and are easily detectable. Mapping these big galaxies thus provides an effective way to make a map of the rest of the galaxies in the universe.

Such maps are a boon to the scientists as they can retrace the history of the universe over the last seven billion years based on which they can estimate how much of the universe is made up of "dark matter" and "dark energy".

"Dark matter and dark energy are two of the greatest mysteries of our time," said David Schlegel of Lawrence Berkeley National Laboratory, who led the SDSS-III effort to map these galaxies and quasars. "We hope that our new map of the universe can help someone solve the mystery."

That map of the universe is the centerpiece of DR9. The release includes images of 200 million galaxies and spectra of 1.35 million galaxies, including new spectra of 540,000 galaxies from when the universe was half its present age. Quasars are the brightest objects in the distant universe provide another way to measure the distribution of matter in the universe.

"With these better estimates, we can look back at the history of our galaxy," said Connie Rockosi of the University of California, Santa Cruz, who leads the SDSS-III's Milky Way study. "We can tell the story of how smaller galaxies came together to build up the Milky Way we see today."

"The most fun part of making this data available online is knowing that anyone on the Internet can now access the very same data and search tools that professional astronomers use to make exciting discoveries about our universe," said Ani Thakar of Johns Hopkins University.