Black holes are known to merge, but a new theoretical study explores whether one could ever split into two. The researchers say extremely rapid rotation might make such a process possible, although the conditions would be unusually restrictive.
Published in Physical Review D, the study examines the physical and thermodynamic constraints that normally keep black holes from breaking apart. For a non-rotating black hole, splitting into two smaller ones would reduce total entropy, making the process thermodynamically unfavorable.
The calculations suggest that sufficiently fast rotation could open a narrow exception. However, the two resulting black holes would also have to move apart rather than fall back together. According to co-author Francesco Sannino, this requirement leaves a possible window mainly for black holes spinning close to their maximum rate.
The paper’s title, “When Black Holes Admit Pair-of-pants Topologies,” describes how the black hole’s boundary, or horizon, might look across space and time: one structure dividing into two branches. The researchers also considered theoretical models with extra dimensions, where some black-hole-like objects may be unstable and fragmentation could be thermodynamically favored in certain cases. Whether such a process can actually occur remains unresolved.
The team cannot yet estimate how likely a split would be, since the answer may depend on how gravity behaves beyond Einstein’s theory. Sannino said small primordial black holes may be more prone to splitting than larger astrophysical ones. One possible indirect clue could come from gamma-ray observations: telescopes such as Fermi-LAT could search for signals from tiny black-hole fragments that might form during mergers. No black-hole split has been confirmed.
Sources: ScienceDaily.