Black holes rotate, as the vast majority of celestial bodies. But they are not rotating alone. Surrounding every black hole there is matter, typically in the form of dust. Black holes and matter waltz together, each one influencing the other, as described by Einstein's equations of general relativity. The complexity of these equations makes it very difficult to analyze the interaction between black holes and the surrounding matter, especially because of the black hole’s rotation. Thus, until now most studies resorted to computer simulations or to simplified models, for example, by neglecting the influence of the matter on the black hole or the rotation of space-time.
In a recent paper published in Physical Review D (R), Delsate, Rocha and Santarelli identify a novel scenario in which the full interactions can be addressed in rotating systems, and in this sense constitutes a better approximation to reality. Adopting a mathematical model that considers space-time as having five dimensions -- instead of the usual four -- they were able to treat the interplay between rotating black holes and their surrounding matter with a similar degree of simplicity as in a nonrotating context. This work introduces a framework that can be used in the future to deepen our understanding of realistic black holes.
Figure: Matter falling into a rotating black hole spacetime. Credit: JRocha.
