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Scientists have explained the “impossible” black hole merger
The collision took place seven billion years ago. In 2023, gravitational wave detectors recorded the merger of two black holes located seven billion light-years away. However, analysis revealed that this event seemed to defy the known laws of physics, reports Science Alert.
The black holes were moving faster than any previously observed, and their masses fell within a range where black holes were not expected to exist.
When massive stars reach the end of their lives, they explode as supernovae, leaving behind black holes. But stars with masses between 70 and 140 times that of the Sun experience a different fate: they explode so violently that nothing remains—no black hole is formed, only empty space.
The merger, known as GW231123, broke this fundamental rule. Both black holes had masses within this forbidden range and rotated near the speed of light, twisting spacetime like whirlpools.
Ore Gottlieb and colleagues at the Flatiron Institute’s Center for Computational Astrophysics discovered what others had overlooked: magnetic fields.
The team simulated the life of a 250-solar-mass star. By the end of its life, nuclear burning reduces the mass to about 150 solar masses. When the star collapses, a rotating disk of stellar remnants forms around the newborn black hole, threaded with strong magnetic fields.
At this stage, the magnetic fields change everything. Normally, the disk feeds matter into the black hole, but strong magnetic fields exert pressure, ejecting up to half of the star’s mass at nearly the speed of light.
This drastically reduces the final mass of the black hole and affects its rotation rate. Simulations showed that stronger magnetic fields produce lighter black holes with slower spins, while weaker fields create heavier, faster-spinning black holes.
This relationship suggests a pattern linking black hole mass and rotation, offering a new way to understand the formation of these cosmic giants.
