New 3D map of massive galaxies and black holes offers clues to dark matter, dark energy

October 3, 2012, New York University

(—Astronomers have constructed the largest-ever three-dimensional map of massive galaxies and distant black holes, which will help the investigation of the mysterious "dark matter" and "dark energy" that make up 96 percent of the universe.

The map was produced by the Sloan Digital Sky Survey III (SDSS-III).

Early last year, the SDSS-III released the largest-ever image of the sky, which covered one-third of the . The new data, "Data Release 9" (DR9), which publicly releases the data from the first two years of this six-year project, begins expansion of this earlier image into a full three-dimensional map.

"What really makes me proud of this survey is our commitment to creating a legacy for the future," says Michael Blanton, an NYU physics professor who led the team that prepared DR9. "Our goal is to create a that will be used long after we are done, by of astronomers, , 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 Spectroscopic Survey (BOSS), which will eventually measure the positions of 1.5 million over the past seven billion years of cosmic time, as well as 160,000 quasars—giant actively feeding on stars and gas—from as long ago as 12 billion years ago.

With such a map, scientists can retrace the history of the universe over the last seven 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 even more mysterious force that drives the accelerating .

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. Spectra show how much light a galaxy gives off at different wavelengths. Because this light is shifted to longer, redder wavelengths as the universe expands, spectra allow scientists to figure out how much the universe has expanded since the light left each galaxy. The galaxy images, plus these measurements of expansion, are combined by SDSS-III scientists to create the three-dimensional map released with DR9.

Distant quasars provide another way to measure the distribution of matter in the universe. Quasars are the brightest objects in the distant universe and their spectra show intricate patterns imprinted by the large-scale clumping of intergalactic gas and underlying dark matter that lies between each quasar and the Earth.

These new data are not only helping us understand the distant universe, but also our own cosmic backyard, the Milky Way galaxy. DR9 includes better estimates for the temperatures and chemical compositions of more than half a million stars in our own galaxy.

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2.8 / 5 (4) Oct 03, 2012
This news would be much more useful if you provided more hard data - who can actually access the database (free/paid?), where can we find it, does it have it's own software layer or is it purely coordinates database, etc.

It's like NASA's Curiosity reports: "we analysed a rock, here's a picture". And no information about the actual mineral composition.
2.3 / 5 (3) Oct 03, 2012
The PR guy that penned this puff piece didn't spend five years in Journalism school to provide you with hard data.
1 / 5 (2) Oct 03, 2012
The PR guy that penned this puff piece didn't spend five years in Journalism school to provide you with hard data.

I guess it was written specifically for people who will never ever have anything to do with described project. After another 5 years he may be qualified to write for dogs and other house pets.
5 / 5 (1) Oct 03, 2012
It's not hard to find:

For example


There's a tutorial at the bottom of the left hand panel.
5 / 5 (1) Oct 04, 2012
who can actually access the database, where can we find it, does it have it's own software layer or is it purely coordinates database, etc.

Everybody can access it. Just go to their website. They also have free tools for viewing.

Google is your friend. (At least it should be before shooting your mouth off)
not rated yet Oct 06, 2012
I'm an amateur astronoom, acces too the SDDS data is very simply. You can use the tools discribed by Fleetfoot.
Or you can download TOPCAT ( ), this is a FREE software for handling the astronomical FITS files. The fits files gives position (RA, Dec and z), magnitude and more for 100 000 sometimes 1 000 000 objects.
Most of all the "FITS" files do have an arxiv paper. The latest data release from SDDS is made in end of Juli, the arxiv paper you can find on The FITS file you can download at http://www.sdss3....cess.php , take the specObj-dr9.fits file.
Also interesting are the FITS on http://www.sdss.o...dex.html Most of these have also arxiv papers. My favorite for the moment is A Catalog of Quasar Properties from SDSS DR7.
Greatings, Wouter

not rated yet Oct 06, 2012
Sorry for my writing.
It's SDSS and not SDDS.
Also astronomer and not Dutch "astronoom" :-)

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