The linear stability of Reissner-Nordström spacetime: the full subextremal range
Elena Giorgi
TL;DR
This work establishes the linear stability of subextremal Reissner–Nordström spacetimes to gravitational and electromagnetic perturbations for the full subextremal range |Q|<M. It introduces a symmetric mixed spin ±1/±2 Regge–Wheeler system built from gauge-invariant perturbation quantities, and defines a combined energy-momentum tensor that enables cancellations without assuming small charge. Through physical-space analysis, the authors prove uniform energy bounds, Morawetz (integrated decay), and an r^p-hierarchy that yields decay rates for the coupled perturbations, thereby completing the linear stability program in this regime. The approach leverages the adjoint-sphere structure of the coupling to obtain a positive, conserved energy and robust decay estimates, integrating prior results on gauge-invariant quantities with a new symmetric formulation. The results are significant for understanding perturbative dynamics around RN black holes and provide a foundation for potential nonlinear stability analyses in the subextremal setting.
Abstract
We prove the linear stability of subextremal Reissner-Nordström spacetimes as solutions to the Einstein-Maxwell equation. We make use of a novel representation of gauge-invariant quantities which satisfy a symmetric system of coupled wave equations. This system is composed of two of the three equations separately derived in previous works, where the estimates required arbitrary smallness of the charge. Here, the estimates are obtained by defining a combined energy-momentum tensor for the system in terms of the symmetric structure of the right hand sides of the equations. We obtain boundedness of the energy, Morawetz estimates and decay for the full subextremal range |Q|<M, completely in physical space. Such decay estimates, together with the estimates for the gauge-dependent quantities of the perturbations previously obtained, settle the problem of linear stability to gravitational and electromagnetic perturbations of Reissner-Nordström solution in the full subextremal range |Q|< M.
