Supermassive black holes discovered

By Paul Harper

Artist’s concept illustration of a quasar, or feeding black hole. Credit: NASA/ESA
Artist’s concept illustration of a quasar, or feeding black hole. Credit: NASA/ESA

A NASA telescope has unearthed a "bonanza" of new supermassive black holes and extreme galaxies called hot DOGs.

Images from the Wide-field Infrared Survey Explorer (WISE) mission have revealed millions of possible dusty black holes and about 1,000 even dustier objects believed to be among the brightest galaxies ever found, NASA said.

The powerful galaxies burn brightly with infrared light and are nicknamed hot DOGs - or dust-obscured galaxies.

"WISE has exposed a menagerie of hidden objects," WISE program scientist Hashima Hasan said. "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."

NASA said the findings are helping astronomers better understand how galaxies and the giant black holes at their centre evolve together.

The giant black hole at the centre of our Milky Way galaxy, Sagittarius A*, for example, 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, may even shut down star formation in galaxies, NASA said.

Astronomers have used WISE to identify 2.5 million actively feeding supermassive black holes across the full sky, some more than 10 billion light-years away. About two-thirds of these black holes have never been detected before because dust blocks their visible light, NASA said. However the WISE telescope can identify them as the black holes warm the dust, causing it to glow in infrared light.

Researchers hunting for the bright hot DOGs have also identified about 1,000 candidates.

NASA said the extreme galaxies can pour out more than 100 trillion times as much light as our own sun. However they are so dusty they only appear in the longest wavelengths of infrared light captured by WISE.

NASA's Spitzer Space Telescope followed up on the discoveries in more detail and found the DOGs are churning out new stars, as well as hosting supermassive black holes.

"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 galaxies, and project scientist for WISE at Jet Propulsion Laboratory. "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'."

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