The Linear Stability of Weakly Charged and Slowly Rotating Kerr-Newman Family of Charged Black Holes

In this paper, we prove the linear stability of weakly charged and slowly rotating Kerr-Newman black holes under coupled gravitational and electromagnetic perturbations. We show that the solutions to the linearized Einstein-Maxwell equations decay at an inverse polynomial rate to a linearized Kerr-Newman solution plus a pure gauge term. This work builds on the framework developed in Häfner (Invent Math 223(3):1227–1406, 2021) for the study of the Einstein vacuum equations. We work in the generalized wave map and Lorenz gauge. The proof involves the analysis of the resolvent of the Fourier transformed linearized Einstein-Maxwell operator on asymptotically flat spaces, which relies on recent advances in microlocal analysis and non-elliptic Fredholm theory developed in Vasy (Invent Math 194(2):381–513, 2013). The most delicate part of the proof is the description of the resolvent at low frequencies.