Nasa’s Wide-Field Infrared Survey Explorer (WISE) sees in wavelengths correlated with heat, which has enabled the discovery of “a bonanza of black holes in the universe,” according to astronomer Daniel Stern of NASA’s Jet Propulsion Laboratory. WISE showed up three times as many black holes as have been found by comparable surveys, adding 2.5 million new sources across the sky. “We’ve got the black holes cornered,” added Stern
Scientists already know that most large galaxies have black holes at their centres that can suck in gas, dust and stars. But these new finds will help them work out how galaxies and black holes form and how the two evolve together.
The black holes that WISE has been so successful in seeking out aren’t the small, dense objects created by the collapse of dead stars, but rather “supermassive” black holes that feed on matter falling into them. Called ‘quasars’ these are some of the brightest objects in the universe because of light given off by the matter that falls in.
“We expected that there should be this large population of hidden quasars in the universe, but WISE can now identify them across the sky,” Stern said. “We think these quasars are really important for shaping how galaxies look today.”
In addition to the mega black holes, WISE has also shown turned up a smaller population of rarer hot, dust-obscured galaxies, which are nicknamed “hot DOGs.” These are also thought to be extremely bright, but appear very faint to us because their light is shrouded by dust.