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Scientists detect biggest ever merger of two massive black holes just beyond the Milky Way

The collision of two black holes
The collision of two black holes - an event detected for the first time by the Laser Interferometer Gravitational-Wave Observatory, or LIGO - is seen in this still from a computer simulation from 2017. Picture: Alamy

By Rebecca Henrys

Scientists have detected the collision of two massive black holes merging beyond the Milky Way.

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The two black holes, each with a mass more than 100 times that of the sun, had been circling each other for a while before finally colliding to form an even bigger black hole about 10 billion light years from Earth.

The new black hole is believed to be up to 265 times more massive than the sun.

It was discovered by scientists at the Laser Interferometer Gravitational-wave Observatory (Ligo) and is the biggest merger ever recorded.

"These are the most violent events we can observe in the universe, but when the signals reach Earth, they are the weakest phenomena we can measure," said Prof Mark Hannam, the head of the Gravity Exploration Institute at Cardiff University.

"By the time these ripples wash up on Earth they are tiny."

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The signal was recorded when it hit detectors on Earth sensitive enough to detect shudders in space-time thousands of times smaller than the width of a proton.

Evidence for the collision arrived in November when two detectors in Washington and Louisiana, operated by Ligo, twitched at the same time.

The detectors stretched and squeezed for one-tenth of a second due to the sudden spasm in space-time caused by a new black hole being formed by the two merging.

"These are the highest masses of black holes we’ve confidently measured with gravitational waves," said Hannam, a member of the Ligo scientific collaboration.

"And they’re strange, because they are slap bang in the range of masses where, because of all kinds of weird things that happen, we don’t expect black holes to form."