# Stefanos Aretakis: Observational signatures for extremal black holes

**Time: **
Tue 2019-11-26 10.00 - 11.00

**Lecturer: **
Stefanos Aretakis, University of Toronto

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

Abstract

The event horizon and the Cauchy horizon of an extremal black hole admit conserved charges associated with scalar perturbations. We will see that these charges are externally measurable from null infinity. This suggests that these charges have the potential to serve as an observational signature for extremal black holes. The proof of this result is based on obtaining precise late-time asymptotics for the radiation field of outgoing perturbations.