Black holes are heavy. They are the densest objects in the universe, so massive that their gravitational pull doesn’t even let light escape (hence the name).
But it seems even in the world of black holes there are monstrous objects that are in a league of their own.
This week, astronomers found a black hole 33 billion times heavier than our sun, approaching the upper limit of how large black holes can theoretically become. The cosmic giant sits at the centre of the supergiant elliptical galaxy Abell 1201, 2.7 billion light years from Earth.
So large is the black hole that it has been given the very rare designation: “ultramassive black hole”.
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Black holes are the collapsed cores of massive stars that have stopped producing energy.
Smaller black holes can be in the range of 10 to 100 times the mass of the sun (a solar mass). Supermassive black holes can be millions or even billions of solar masses. Ultramassive black holes are between tens of billions of solar masses.
The heaviest black hole known in the universe is the aptly named TON 618, estimated to be 66 billion times the mass of our sun.
While only half that mass, the newly discovered ultramassive black hole in the centre of Abell 1201 is still a monster. It is over 8,000 times heavier than Sagittarius A* – the supermassive black hole at the centre of our Milky Way galaxy.
The ultramassive black hole was also the first black hole to be discovered using gravitational lensing.
Gravitational lensing is when a massive object, like a galaxy, bends the light from a more distant object, thereby magnifying it.
A video showing how Astronomers used gravitational lensing to discover a black hole 30 billion times the mass of the sun in a galaxy 2 billion light years away. Credit: Durham University.
A team led by researchers at Durham University in the UK, was able to use gravitational lensing data from NASA’s Hubble telescope and supercomputer simulations at the DiRAC HPC facility, to match the images received from the telescope to the simulated effect of an ultramassive black hole.
“Most of the biggest black holes that we know about are in an active state, where matter pulled in close to the black hole heats up and releases energy in the form of light, X-rays, and other radiation,” says Dr James Nightingale from Durham University.
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“However, gravitational lensing makes it possible to study inactive black holes, something not currently possible in distant galaxies. This approach could let us detect many more black holes beyond our local universe [the area in the universe nearby to our galaxy] and reveal how these exotic objects evolved further back in cosmic time.”
The research is published in the Monthly Notices of the Royal Astronomical Society.
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