Black holes with magnetic field ‘hair’ shed it in loops of hot plasma

By Leah Crane

Black holes with “hair” will quickly go bald. A key theoretical prediction about black holes called the no-hair theorem states that an isolated black hole can be described by just three numbers – its mass, spin and charge – and any other properties, or “hair”, are irrelevant. Now, a set of detailed simulations has shown how black holes can shed a magnetic field to comply with the no-hair theorem.

When a black hole forms from a magnetised star, it is born with a magnetic field. How …