A big, hairy black-hole bomb?

Black holes have long been believed to have “no hair.” It’s a (somewhat peculiar) metaphor for the notion that once matter zooms past a black hole’s point-of-no-return event horizon, it leaves no trace of its existence, forever inaccessible to outside observers.

But new research suggests that certain black holes could indeed have “long hair,” in the form of a cloud of particles created through a bomb-like process.

William East of Perimeter Institute and Frans Pretorious of Princeton University recently published a paper, in Physical Review Letters, in which they describe simulations of a spinning solar-mass black hole.

They found that a process called superradiance – in which particles and electromagnetic radiation scatter and gain energy from a black hole’s angular momentum – could create a cloud of bosons that extends like hair outside the event horizon.

Check out an APS Physics Viewpoint on the subject, a summary article at Physics World, and read the team’s paper at Physical Review Letters.