Black holes just became more terrifying and impressive than they already are, as recent research shows that they consume at much faster rates than previously expected.
Changing the way astrophysicists understand black holes, a study from a team at Northwestern University used supercomputer simulations to more accurately track the consumption rates of black holes.
These high-resolution 3D simulations show spinning black holes twisting up the surrounding space-time, ripping apart the whirlpool of gas that both encircles and feeds the black hole. This results in the gas whirlpool tearing into inner and outer disks.
These whirlpools of gas are known as accretion disks. As the name suggests, they take the shape of a disk, flowing with gas, plasma, dust, and other particles orbiting a gravitational field of an object – in this case, the black hole.
First, the black hole devours the inner disk, and then debris from the outer disk spills inwards, refilling the gap left behind with the process repeating.
The 3D simulations showed one cycle of this process takes just a few months – a far shorter process compared to the hundreds of years that have previously been suggested by researchers.
This new research could help to explain the erratic behaviour of bright objects in the night sky, including quasars – bright galactic cores falling into black holes – which abruptly flare up and then vanish.
“Classical accretion disk theory predicts that the disk evolves slowly,” said Nick Kaaz, who led the study. “But some quasars – which result from black holes eating gas from their accretion disks – appear to drastically change over time scales of months to years.
“This variation is so drastic. It looks like the inner part of the disk – where most of the light comes from – gets destroyed and then replenished. Classical accretion disk theory cannot explain this drastic variation. But the phenomena we see in our simulations potentially could explain this.”
Changing the way we understand black holes
Previous studies suggested that accretion disks, while dramatic in nature, are relatively orderly. This research posed that gas and particles swirled around black holes, gradually feeding the black hole over a process of hundreds of thousands of years.
“For decades, people made a very big assumption that accretion disks were aligned with the black hole’s rotation,” Kaaz said.
“But the gas that feeds these black holes doesn’t necessarily know which way the black hole is rotating, so why would they automatically be aligned? Changing the alignment drastically changes the picture.”
These new simulations demonstrate that the tearing region – where the inner and outer sub-disks disconnect – is the location of a black hole feeding frenzy. While friction tries to keep the disk together, the twisting space-time by the black hole wants to pull it apart.
“There is competition between the rotation of the black hole and the friction and pressure inside the disk,” Kaaz said. “The tearing region is where the black hole wins. The inner and outer disks collide with each other. The outer disk shaves off layers of the inner disk, pushing it inwards.”
Not only do these simulations potentially explain quasars, but they could also answer ongoing questions about the nature of black holes including how they form, how long for, and what we are actually seeing via telescopes when black holes are observed.
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