Near-horizon Kerr Magnetosphere

TL;DR

This paper uses near-horizon conformal symmetry of rapidly spinning black holes to derive universal properties of their magnetospheres, revealing conditions for the black hole Meissner effect and implications for high-energy particle collisions.

Contribution

It provides analytic expressions for the near-horizon magnetosphere and clarifies the conditions under which the black hole Meissner effect occurs or is violated.

Findings

Meissner effect holds for free Maxwell fields

Meissner effect is violated for force-free fields

Near-horizon plasma particles are infinitely boosted in the extremal limit

Abstract

We exploit the near-horizon conformal symmetry of rapidly spinning black holes to determine universal properties of their magnetospheres. Analytic expressions are derived for the limiting form of the magnetosphere in the near-horizon region. The symmetry is shown to imply that the black hole Meissner effect holds for free Maxwell fields but is generically violated for force-free fields. We further show that in the extremal limit, near-horizon plasma particles are infinitely boosted relative to accretion flow. Active galactic nuclei powered by rapidly spinning black holes are therefore natural sites for high-energy particle collisions.