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Space

Two huge black holes merged into one and went flying across the cosmos

A supermassive black hole that doesn't appear to be where we would expect seems to be travelling at more than a thousand kilometres per second – the result of a giant cosmic collision

By Alex Wilkins

6 March 2025

An image of the quasar 3C 186, taken by the Hubble Space Telescope

NASA’s Goddard Space Flight Center

A rare collision between two supermassive black holes (SMBH) appears to have sent the resulting merger speeding through the universe, making it one of the fastest-moving black holes we have ever seen.

Astronomers have long puzzled over how the gargantuan black holes at the centres of galaxies can grow to be so large. One possible route is for smaller – but still extremely massive – black holes to merge together, but there has been little direct evidence of this happening.

Article amended on 18 March 2025

We have clarified the blueshift of the light from the black hole

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