Filippo Camilloni: Moving away from the Near-Horizon Attractor of the Extreme Kerr Force-Free Magnetospheres


Force-free electrodynamics is a non-linear regime of Maxwell’s equations often employed to provide a minimal non-trivial level of description for pulsar and black hole magnetospheres. For a solution of this system to be physically meaningful the field has to be magnetically dominated, F= B2 - E2 > 0, however no analytic solution is known to respect this requirement in the background of a highly-spinning black hole. In this talk I will show how the Near-Horizon Extreme Kerr (NHEK) region might play a crucial role for the construction of sensible models of extreme Kerr magnetospheres . Any stationary and axisymmetric force-free solution in the extreme Kerr background is observed to converge to an attractor in the NHEK region. We used this attractor as an universal starting point to develop a new perturbative approach, showing that at the second order in perturbation theory it is possible to find magnetically-dominated force-free fields. A similar attractor mechanism occurs in the Near-Horizon Near-Extreme Kerr (near-NHEK) region of a nearly-extreme Kerr black hole, thus providing a way to extend this formalism outside extremality.


Event organized by CEICOCentral European Institute for Cosmology and Fundamental Physics.
Please contact Roberto Oliveri or Gizem Sengor for further info.