THAT sure is a flaming big hole. Astronomers have discovered a black hole with a mass 12 billion times that of the sun. It seems to have reached that size when the universe was less than a billion years old, which creates a puzzle. Current models suggest that it could not have grown so big so soon after the big bang.
of Peking University in Beijing, China, and his colleagues found the black hole by searching through data from sky surveys, looking for bright objects called quasars.
One candidate, J0100+2802, looked particularly promising, so the team used telescopes in China and the US to analyse its light. By measuring how much the light had been stretched out by the expansion of the universe, they calculated that it is 12.8 billion light years from Earth.
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Quasars, which emit vast quantities of light, are thought to surround black holes and be powered by gas heating up and glowing as it falls into the hole. Measuring the properties of this gas can in turn determine the black hole鈥檚 mass. J0100+2802 is about four times as bright as the previous brightest quasar at this distance, and its black hole is a monster at 12 billion times the mass of our sun (Nature ).
There are bigger black holes out there, but it is the age of this one that鈥檚 troubling. It reached this size just 900 million years after the big bang 鈥� which in black hole terms isn鈥檛 very long.
鈥淓veryone thinks of black holes as these great dangerous things that swallow up anything in their vicinity,鈥� says of Imperial College London. But that鈥檚 not the case. 鈥淚f you try to force-feed it you get a traffic jam on the way in and it gets very dense.鈥�
聯If you try to force-feed a black hole, you get a traffic jam on the way in and everything heats up聰
This heating creates quasars, but if too much material falls in too quickly, it becomes hot enough to force new material out of the gravitational pull of the black hole. Such an early giant breaks the theorised growth limits, says Wu. 鈥淚t either requires very special ways to grow the black hole, or requires that a huge seed black hole existed when the universe was less than 300 million years old.鈥�
Another explanation is that small black holes somehow form in clusters in the early universe, and grow massive by merging with each other rather than sucking up gas, says Mortlock. But large black holes made this way won鈥檛 glow, so we can鈥檛 see them.
None of these solutions is fully supported by existing theories, says Mortlock, so we will probably need bigger telescopes to peer even further back into the past. 鈥淵ou鈥檙e coming up with theories to try to explain what are pretty close to the most distant objects we can see,鈥� he says.
This article appeared in print under the headline 鈥淕iant black hole grew too fast鈥�
