Geometry & Topology Seminar

**Note time change**​

Henri Roesch, Columbia University

"Horizon Stability and the Null Penrose Inequality"

We introduce a new quasi-local mass with interesting properties along null flows off of a 2-sphere in space-time or, equivalently, foliations of a null cone. We also show how certain convexity assumptions on the null cone allow for a proof of the Penrose Inequality. On a MOTS, we find these convexity assumptions need to be sharp; therefore, we explore existence within a Weakly Isolated Horizon. Building on a lemma of S. Alexakis, this allows us to show that the Penrose Inequality is stable under small perturbations of the Schwarzschild null cone.

MC 5403