Schwinger-Regulated Electromagnetic Evolution in Kerr-Newman Black Holes

We present a complete theoretical framework describing how the Schwinger effect-vacuum pair production in strong electric fields-dynamically regulates the electromagnetic properties of Kerr-Newman black holes. Beginning from first principles in general relativity and quantum field theory, we derive the coupled evolution of charge and magnetic fields during discharge. The key result is a self-consistent discharge equation whose exact solution, the Aasmaan-Schwinger discharge function, shows that black hole charge decays as Q(t) ∝ 1/ ln t at late times. Crucially, because the intrinsic magnetic field of a Kerr-Newman black hole scales as B ∝ Qa, Schwinger-driven charge loss inevitably forces magnetic field decay, preserving the ratio B 2 /E 2 throughout the process. This provides a novel, unified mechanism that explains why astrophysical black holes are observed as near-neutral objects and why their intrinsic magnetic fields cannot be sustained independently of charge. The work highlights Schwinger discharge as a natural enforcer of cosmic censorship, preventing black holes from reaching extremal charge limits