NASA's WISE Survey Reveals Millions of Black Holes and About 1,000 Hot DOGs

Posted on August 31, 2012

A NASA's Wide-field Infrared Survey Explorer (WISE) mission has led to the discovery of millions of black holes. The survey also found about 1,000 extreme galaxies called hot DOGs, or dust-obscured galaxies. The powerful galaxies, which burn brightly with infrared light, are nicknamed hot DOGs.

Hashima Hasan, WISE program scientist at NASA Headquarters in Washington, says, "WISE has exposed a menagerie of hidden objects. We've found an asteroid dancing ahead of Earth in its orbit, the coldest star-like orbs known and now, supermassive black holes and galaxies hiding behind cloaks of dust."

WISE scanned the whole sky twice in infrared light, completing its survey in early 2011. The telescope captured millions of images of the sky. All the data from the mission have been released publicly, allowing astronomers to dig in and make new discoveries.

In one study, astronomers used WISE to identify about 2.5 million supermassive black holes across the full sky, stretching back to distances more than 10 billion light-years away. About two-thirds of these objects never had been detected before because dust blocks their visible light.

Daniel Stern of NASA's Jet Propulsion Laboratory, Pasadena, Calif., lead author of the WISE black hole study, says, "We've got the black holes cornered. WISE is finding them across the full sky, while NuSTAR is giving us an entirely new look at their high-energy X-ray light and learning what makes them tick."

In two other WISE papers, researchers report finding what are among the brightest galaxies known. So far, they have identified about 1,000 candidates. These extreme objects can pour out over 100 trillion times as much light as our sun. They are so dusty, however, that they appear only in the longest wavelengths of infrared light captured by WISE. Data from NASA's Spitzer Space Telescope indicates these DOGs are also busy churning out new stars.

Peter Eisenhardt, lead author of the paper on the first of these bright, dusty galaxies, and project scientist for WISE at JPL, says, "These dusty, cataclysmically forming galaxies are so rare WISE had to scan the entire sky to find them. We are also seeing evidence that these record setters may have formed their black holes before the bulk of their stars. The 'eggs' may have come before the 'chickens.'"

Three papers describing the findings are being published in the Astrophysical Journal. The three technical journal articles, including PDFs, can be found here, here and here.

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BLACK HOLES