A jackpot of previously unknown black holes across the universe has been discovered by the infrared eyes of a prolific NASA sky-mapping telescope.
The cosmic find comes from data collected by NASA’s Wide-field Infrared Survey (WISE) telescope, which scanned the entire sky in infrared light from December 2009 to February 2011. The full catalog of observations by WISE during its mission was publicly released in March, and astronomers are still poring through this celestrial trove for discoveries.
“WISE has found a bonanza of black holes in the universe,” astronomer Daniel Stern of NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, Calif., said during a news briefing today (Aug. 29). WISE turned up about three times as many black holes as have been found by comparable surveys in visible light, offering up a total of 2.5 million new sources across the sky.
Professor Andrew King from the Department of Physics and Astronomy, University of Leicester, said: “Almost every galaxy has an enormously massive black hole in its centre. Our own galaxy, the Milky Way, has one about four million times heavier than the sun. But some galaxies have black holes a thousand times heavier still. We know they grew very quickly after the Big Bang.”
“These hugely massive black holes were already full—grown when the universe was very young, less than a tenth of its present age.”
Black holes grow by sucking in gas. This forms a disc around the hole and spirals in, but usually so slowly that the holes could not have grown to these huge masses in the entire age of the universe. `We needed a faster mechanism,’ says Chris Nixon, also at Leicester, “so we wondered what would happen if gas came in from different directions.”
Nixon, King and their colleague Daniel Price in Australia made a computer simulation of two gas discs orbiting a black hole at different angles. After a short time the discs spread and collide, and large amounts of gas fall into the hole. According to their calculations black holes can grow 1,000 times faster when this happens.
“If two guys ride motorbikes on a Wall of Death and they collide, they lose the centrifugal force holding them to the walls and fall,” says King. The same thing happens to the gas in these discs, and it falls in towards the hole.
This may explain how these black holes got so big so fast. “We don’t know exactly how gas flows inside galaxies in the early universe,” said King, “but I think it is very promising that if the flows are chaotic it is very easy for the black hole to feed.”
The two biggest black holes ever discovered are each about ten billion times bigger than the Sun.
A monstrous black hole at the heart of one galaxy is being devoured by a still larger black hole in another, scientists say. The discovery is the first of its kind.
At the centers of virtually all large galaxies are black holes millions to billions of times the mass of the sun. Models simulating the formation and growth of galaxies predict their black holes evolve as the galaxies do, by merging with others.
Astronomers had witnessed the final stages of the merging of galaxies of equal mass, so-called major mergers. Minor mergers between galaxies and smaller companions should be even more common, but, strangely, these had not been seen until now.