17 September 2020, 13:15 (EET), online seminar

• Vasil Dimitrov (KU Leuven)
• Title: Gravitational Waves, Holography, and Black Hole Microstates
• Abstract: Gravitational wave observations of the near-horizon region of black holes lend insight into the quantum nature of gravity. In particular, gravitational wave echoes have been identified as a potential signature of quantum gravity-inspired structure near the horizon. In this talk, we connect such observables to the language of black hole microstates in string theory and holography. To that end, we propose a toy model describing the AdS_3 near-horizon region of five-dimensional black holes, inspired by earlier work of Solodukhin. This model captures key features of recently constructed microstate geometries, such as the presence of echoes, and allows us to make two observations. First, we relate the language of AdS/CFT, in particular the holographic retarded two-point correlator, to effective parameters modeling the structure that are used in flat space gravitational wave literature. Second, using a microcanonical ensemble average over geometries, we find support for the claim that the gravitational wave echo amplitude in a typical quantum microstate of the black hole is exponentially suppressed by the black hole entropy.