Like a shaggy dog in springtime, some black holes need to be shed. New computer simulations reveal how black holes might discard their magnetic fields.
Unlike dogs with their varied fur coats, isolated black holes are mostly identical. they’re characterized by only their mass, spin, and charge. consistent with a rule referred to as the no-hair theorem, the other distinguishing characteristics, or “hair,” are quickly removed. that has magnetic fields.
The rule applies to black holes during a vacuum, where magnetic fields can simply slip away. But, says astrophysicist Ashley Bransgrove of Columbia University, “what we were brooding about is what happens during a more realistic scenario.” A magnetized region would typically be surrounded by electrically charged matter called plasma, and scientists didn’t skills — or maybe if — such black holes would undergo hair loss.
Black holes are often born with magnetic fields or gain them later, for instance by swallowing a star, a highly magnetic dead star. When Bransgrove and colleagues simulated the plasma surrounding a magnetized region, they found that a process called magnetic reconnection allows the magnetic flux to flee the region. The magnetic flux lines that map the field’s direction break apart and reconnect. Loops of magnetic flux from around blobs of plasma, a number of which blast outward, while others fall under the region. That process eliminates the black hole’s magnetic flux, the researchers report within the July 30 Physical Review Letters.
Magnetic reconnection in balding black holes could spew X-rays that astronomers could detect. So scientists may at some point glimpse a region losing its hair.