University of Leicester astronomer discovers millions of black holes

Posted by pt91 at Sep 07, 2012 01:40 PM |
Professor Andrew Blain contributes to NASA’s WISE mission discoveries
University of Leicester astronomer discovers millions of black holes

This image zooms in on one small region of the WISE sky, covering an area about three times larger than the moon. The WISE quasar candidates are highlighted with yellow circles. Image credit: NASA/JPL-Caltech/UCLA

Issued by University of Leicester Press Office on 31 August 2012

A University of Leicester astronomer has helped uncover a wealth of previously-hidden supermassive black holes along with some of the largest galaxies ever found.

Professor Andrew Blain, of the University of Leicester’s Department of Physics and Astronomy, has been directly involved in the NASA’s Wide-field Infrared Survey Explorer (WISE) mission, which published new findings this week.

Images from the WISE telescope have revealed millions of dusty black hole candidates across the universe and about 1,000 even dustier objects thought to be among the brightest galaxies ever found. These powerful galaxies that burn brightly with infrared light are nicknamed hot DOGs (dust-obscured galaxies). 

WISE scanned the whole sky twice in infrared light, completing its survey in early 2011. Like night-vision goggles probing the dark, 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. 

Professor Blain has been involved in the project since its inception in 2001, and since coming to Leicester has continued to examine and validate the data from the WISE telescope.

Professor Blain said: “When the WISE mission produces new discoveries, it is not just that it is a good scientific result in itself – it’s a reward for a lot of hard work, and it is always good to find something new and unrecognised.

“The results will help us find out how black holes affect their surroundings – and give us a full measure of how black holes affect the galaxy formation process.

“We hope to use the ALMA telescope in Chile to study in detail various objects which have been found through WISE’s scan.”

The latest findings are helping astronomers better understand how galaxies and the behemoth black holes at their centres grow and evolve together. 

For example, the giant black hole at the centre of our Milky Way galaxy, called Sagittarius A*, has 4 million times the mass of our sun and has gone through periodic feeding frenzies where material falls towards the black hole, heats up, and irradiates its surroundings. Bigger central black holes, up to a billion times the mass of our sun, even may shut down star formation in galaxies. 

Professor Blain contributed to three WISE papers detailing the latest discoveries that were subject of a NASA press conference this week. 

In one study, astronomers used WISE to identify about 2.5 million actively feeding supermassive black holes across the full sky, stretching back to distances more than 10 billion light-years away. About two-thirds of these black holes never had been detected before because dust blocks their visible light. WISE easily sees these monsters because their powerful, accreting black holes heat the dust, causing it to glow in infrared light. 

In two other WISE papers, researchers report finding what are among the brightest galaxies known, one of the main goals of the mission. So far, they have identified about 1,000 candidates. 

These extreme objects can pour out more than 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. NASA's Spitzer Space Telescope followed up on the discoveries in more detail and helped show that, in addition to hosting supermassive black holes feverishly snacking on gas and dust, these DOGs are busy churning out new stars.

"These dusty, cataclysmically forming galaxies are so rare WISE had to scan the entire sky to find them," said Peter Eisenhardt, lead author of the paper on the first of these bright, dusty galaxies, and project scientist for WISE at NASA’s Jet Propulsion Laboratory (JPL). "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.'"

More than 100 of these objects, located about 10 billion light-years away, have been confirmed using the W.M. Keck Observatory on Mauna Kea, Hawaii, as well as the Gemini Observatory in Chile, Palomar's 200-inch Hale telescope near San Diego, and the Multiple Mirror Telescope Observatory near Tucson, Ariz.

The WISE observations combined with data at even longer infrared wavelengths from Caltech's Submillimeter Observatory atop Mauna Kea, Hawaii, revealed that these extreme galaxies are more than twice as hot as other infrared-bright galaxies. One theory is their dust is being heated by an extremely powerful burst of activity from the supermassive black hole.

"We may be seeing a new, rare phase in the evolution of galaxies," said Jingwen Wu of JPL, lead author of the study on the submillimeter observations. All three papers are being published in the Astrophysical Journal. 

Ends

Notes:

For more information, please contact Professor Blain on 0116 223 1772 or at: ab520@le.ac.uk

For the full NASA press release visit: http://www.jpl.nasa.gov/news/news.php?release=2012-265

About WISE

The three technical journal articles, including PDFs, can be found at http://arxiv.org/abs/1205.0811,http://arxiv.org/abs/1208.5517 and http://arxiv.org/abs/1208.5518 .

JPL manages and operates WISE for NASA's Science Mission Directorate, Washington. The principal investigator, Edward Wright, is at UCLA. The mission was competitively selected under NASA's Explorers Program managed by the Goddard Space Flight Center, Greenbelt, Md. The science instrument was built by the Space Dynamics Laboratory, Logan, Utah, and the spacecraft was built by Ball Aerospace & Technologies Corp., Boulder, Colo. Science operations and data processing and archiving take place at the Infrared Processing and Analysis Center at the California Institute of Technology in Pasadena. Caltech manages JPL for NASA. 

For more information about WISE, visit: 
http://www.nasa.gov/wise

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