Mystery of enormous black hole collision solved through magnetic forces, say scientists

A snapshot from a computer simulation showing how a black hole forms and evolves. (Image: Ore Gottleib/Simons Foundation)

Astronomers may have finally solved a cosmic mystery that puzzled them for a year. The strange event, detected in 2023, showed two enormous black holes colliding about 7 billion light-years away. The black holes were far too massive and fast-spinning to fit into any existing theories. Now, scientists believe magnetic fields might hold an answer.

How did astronomers discover the black hole collision?

The event, dubbed GW231123, was the first to be identified by the collaboration working with LIGO, Virgo, and KAGRA. Their detectors picked up the gravitational waves emitted by the violent crash of two enormous black holes. At first, astronomers didn't think such large and rapidly spinning black holes could exist.

These massive stars usually die in colossal explosions called supernovae and leave black holes behind. However, if a star is between 70 and 140 times the Sun’s mass, it is thought to explode in a pair-instability supernova, which completely destroys the star, leaving nothing. “We don’t expect black holes in this mass range,” said Ore Gottlieb, an astrophysicist at the Flatiron Institute’s Center for Computational Astrophysics (CCA) and lead author of the new study. The findings were published in The Astrophysical Journal Letters.

What Role Do Magnetic Fields Play?
To understand the origins of GW231123, Gottlieb and his team ran advanced computer simulations that followed a massive star’s entire life. The first simulation modelled a giant star about 250 times heavier than the Sun. By the time it exploded, it had reduced to about 150 solar masses—just above the mass gap thought to prevent black hole formation.

The second simulation included magnetic fields, which earlier studies had ignored. When a spinning star collapses, it leaves a cloud of gas and dust around the new black hole. Magnetic pressure within this cloud can push some of the material away at nearly light speed, preventing it from falling into the black hole. This process lowers the black hole’s final mass.

Gottlieb said, “No one had looked at these systems this way before. Once you include magnetic fields, everything begins to make sense.” The simulations showed that magnetic fields could eject up to half the star’s mass, leaving a lighter black hole that fits within the observed mass gap.

What Does This Mean for Future Discoveries?
The research also found that the strength of magnetic fields affects a black hole's spin. Stronger magnetic forces eject more material and produce slower-spinning black holes. Weaker fields allow faster rotation and greater mass. This pattern may link a black hole’s weight with its spin rate.

Gottlieb said this discovery could reveal a new connection in black hole physics. “Rotation and magnetic fields may fundamentally change how black holes form,” he explained. The simulations further suggested that such events could emit short bursts of gamma rays, which astronomers might detect with future telescopes.

Finding more systems like GW231123 would help confirm this theory and explain how some of the universe’s most massive and energetic black holes are born. For the time being, the research gives scientists a clearer picture of what happens when stars collapse, spin, and unleash the magnetic power of their final moments.