News

'Bonanza of black holes' discovered by USU-built telescope

By John Hollenhorst
KSL News
August 29, 2012

LOGAN — A Utah-made satellite has discovered a "bonanza of black holes" and has found 1,000 examples of a rare and violent phenomenon that produces the brightest objects in the universe.

NASA announced discoveries Wednesday of some of the "most extreme" features of the heavens after scientists spent months studying images obtained by the orbiting WISE telescope. The Wide-field Infrared Survey Explorer spent more than a year mapping the entire sky with its infrared cameras.

WISE was designed and built at Utah State University's Space Dynamics Laboratory. It's now getting credit for producing images of the brightest, most massive, most violent regions of space.

The spacecraft's name may live on in astronomy books. NASA scientists attached the name "WISE Hot DOGs" to a bizarre class of ultra-massive, super-bright objects. "DOG" is an acronym for "Dust-Obscured Galaxy."

"These are galaxies that we can't see any way except in the infrared" range of light, said USU astrophysicist Shane Larson. "They're absolutely the most luminous objects we've ever seen, tens of billions of times the luminosity of our sun."

Astronomers aren't sure how the WISE Hot DOGs are formed. One possibility is that they're triggered by the collision of two massive galaxies, each with its own black hole in the galactic center. As the two star-systems merge, gases are stirred over vast distances and swirl violently around and into the black holes. It's only because of such interactions that black holes can be seen at all.

The WISE telescope has found over 500 million light sources in the universe.
(Courtesy of NASA)

"We're seeing them heat up the gas in the galaxy," Larson said. "That gas is becoming warmer, hotter than it was. And that makes it visible to our instruments, like WISE."

There may be a WISE Hot DOG in Earth's future. Our own Milky Way galaxy is expected to eventually merge with the Andromeda Galaxy. It's too soon to panic, though; that cosmic collision isn't expected for about two billion years.

The infrared imagery obtained by WISE shows a total of 563 million light sources in the universe, far more than were ever observed before. They include comets, asteroids, moons, planets, stars, galaxies and a set of very cool "stars" known as brown dwarfs.

The discovery of millions of black holes is creating excitement. NASA astronomer Daniel Stern called it a bonanza. "Wise has found this jackpot of black holes," he said, "more than had been found by any previous survey."

NASA scientist Peter Eisenhardt said WISE has given scientists a huge amount of new data to study for years. "It's quite a major advance and quite a good bargain for its field," Eisenhardt said. "We released our data in March and there are now about 175 papers in the published astronomical literature based on WISE data. And that rate is climbing rapidly."

"That's the ultimate reward," said Joel Cardon who was part of the team that designed and built the WISE satellite. "We knew the instrument had survived its bumpy ride into space. And now for the science to be progressing so well is the ultimate reward."

NASA launched the WISE satellite in 2009 and it did nearly all its work in 2010. It's still in orbit, hibernating, until someone spends the money to fire it back up.

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