# Oliver Lindblad Petersen: Cauchy horizons in vacuum spacetimes

**Time: **
Tue 2019-11-19 10.00 - 11.00

**Location: **
Seminar Hall Kuskvillan, Institut Mittag-Leffler

**Participating: **
Oliver Lindblad Petersen, Universität Hamburg

### Abstract

Moncrief and Isenberg conjectured in 1983 that any compact Cauchy horizon in a smooth vacuum spacetime is a smooth Killing horizon. They have proven the conjecture (in dimension 3+1), under the assumptions that the spacetime metric is analytic and the generators are “non-ergodic”. In this talk, we prove that any compact Cauchy horizon with constant non-zero surface gravity in a smooth (as opposed to analytic) vacuum spacetime is a smooth Killing horizon. The method relies on new energy estimates and Carleman estimates for wave equations close to compact Cauchy horizons. This is partly joint work with I. Racz.