Jean-David Jacques (Potsdam)
Oliver Lindblad Petersen (Uni Hamburg)
In a recent paper, Ionescu and Klainerman showed that Killing vector fields on Lorentzian manifolds can be extended using only unique continuation statements for wave equations. Before their work, Killing vector fields were extended by solving linear wave equations, which is significantly more difficult in non-standard situations. In this talk, I will present a new unique continuation theorem through smooth compact characteristic hypersurfaces and discuss its consequences for rigidity of vacuum spacetimes containing compact Cauchy horizons or stationary black holes.