Astrophysicists at the University of Massachusetts at Dartmouth and the University of Rhode Island have disproved the popular notion of black holes called the “no hair theorem,” according to which black holes with the same mass, charge, and rotational speed have no other characteristics that distinguish them from each other. … A new property of black holes, called “gravitational hair”, can be determined by measuring gravitational waves. The article was published in the journal Physical Review D.
The researchers studied solutions to the Einstein equations corresponding to extreme Reissner-Nordstrom black holes (with zero rotation speed), as well as extreme Kerr black holes (rotating). Extreme black holes have minimum mass for a given charge or rotation rate.
For numerical simulations, scientists used several dozen high-performance graphics processors in parallel, each of which is capable of performing up to seven trillion calculations per second.
Scientists have found that there is a special additional quantity that can be used to distinguish extreme Kerr black holes. This parameter, which characterizes gravitational perturbations at the event horizon, depends on how the black hole was formed, and can, in principle, be measured by a distant observer using gravitational waves emitted by an exotic object at finite distances.