Researchers describe conditions for a black hole to split into two — ScienceDaily
An international group of physicists has theoretically investigated the conditions under which one black hole could split into two smaller ones. As ScienceDaily reports, such a process is not completely ruled out by the laws of physics, but it requires extremely specific conditions — above all, the black hole must rotate at nearly the maximum possible speed.
The work was published in the journal Physical Review D under the title When Black Holes Admit Pair-of-pants Topologies. Its authors are Francesco Sannino, Giacomo Cacciapaglia, Manuel Del Piano, and Vania Vellucci.
The entropy barrier
For a non-rotating black hole, splitting into two smaller black holes would be thermodynamically unfavorable. According to the scientists’ calculations, this would reduce the total entropy of the system, which explains why black holes do not normally break apart.
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The situation may change for a black hole rotating at an extremely high speed. At the same time, after splitting, the newly formed black holes must move sufficiently far away from each other; otherwise, they would immediately merge again. According to Professor Francesco Sannino, this requirement almost completely rules out the possibility of splitting, except for objects with rotation close to the maximum possible.
Additional dimensions and the search for signals
The scientists also considered theoretical models with additional spatial dimensions. Some of them contain black hole-like objects that can lose stability and begin to decay. In certain cases, such a process may be thermodynamically favorable, particularly when one of the two black holes is significantly smaller than the other.
The authors note that thermodynamic permissibility does not yet mean that fragmentation will physically occur. The probability of the process depends on the properties of gravity beyond Einstein’s theory. The researchers suggest that small primordial black holes may be more prone to splitting than large astrophysical ones. Possible signals from small fragments that could form during mergers may potentially be searched for by gamma-ray telescopes, including Fermi-LAT.
