Study explores whether rapidly spinning black holes could split
Theoretical calculations suggest a possible opening near maximum rotation, but no black hole has been confirmed to divide.
A theoretical study in Physical Review D suggests that a black hole rotating near its maximum possible rate might be able to divide into two. The researchers have not established whether such fragmentation can physically occur, and there are no confirmed observations of it.
The team examined the restrictions that normally prevent division. Splitting a nonrotating black hole would lower its total entropy, making the change unfavorable under thermodynamics. Their calculations suggest sufficiently rapid rotation could overcome that restriction.
Another constraint sharply limits the possibility: the resulting black holes would have to separate without merging again. Co-author Francesco Sannino, a physics professor at the University of Naples Federico II and the University of Southern Denmark's Quantum Field Theory Center, said accounting for this leaves little room except potentially near maximum rotation.
The researchers also considered theories with extra spatial dimensions. In some cases, division could be thermodynamically favorable, particularly if the resulting objects differed greatly in size. That does not establish that it would happen.
Sannino said the team cannot yet assign a probability because the answer depends on gravity beyond Einstein's theory. He suggested gamma-ray instruments, including Fermi-LAT, could look for indirect signals from tiny fragments potentially produced during black hole mergers.
