174 citations · 225 across the 5 of their papers we have counts for
6 papers
Global existence for systems of nonlinear wave equations with bounded, stable asymptotic systems
Joseph Keir
Some systems of nonlinear wave equations admit global solutions for all sufficiently small initial data, while others do not. The (classical) null condition guarantees that such a…
Evanescent ergosurface instability
Joseph Keir
Some exotic compact objects possess evanescent ergosurfaces: timelike submanifolds on which a Killing vector field, which is timelike everywhere else, becomes null. We show that an…
The weak null condition and global existence using the p-weighted energy method
Joseph Keir
We prove global existence for solutions arising from small initial data for a large class of quasilinear wave equations satisfying the `weak null condition' of Lindblad and Rodnian…
Wave propagation on microstate geometries
Joseph Keir
Supersymmetric microstate geometries were recently conjectured to be nonlinearly unstable due to numerical and heuristic evidence, based on the existence of very slowly decaying so…
Slowly Decaying Waves on Spherically Symmetric Spacetimes and an Instability of Ultracompact Neutron Stars
Joseph Keir
We prove that, in a class of spherically symmetric spacetimes exhibiting stable trapping of null geodesics, linear waves cannot (uniformly) decay faster than logarithmically. When…
Stability, Instability, Canonical Energy and Charged Black Holes
Joe Keir
We use the canonical energy method of Hollands and Wald to study the stability properties of asymptotically flat, stationary solutions to a very general class of theories, consisti…