Holography of the photon ring

Abstract Space-based next-generation interferometers propose to measure the Lyapunov exponents of nearly bound geodesics that comprise photon ring surrounding black hole M87*. We argue these classical equal quantum Ruelle resonances describing late-time approach thermal equilibrium microstate holographically dual any Kerr such as Moreover, we identify ‘near-ring regions’ in phase space fields propagating on exhibit critical behavior, including emergent conformal symmetries. These are analogues for sub-extremal much-studied ‘near-horizon (near-)extremal holes. The symmetries greatly constrain observational predictions fine substructure around M87* and quasinormal gravitational-wave ringdowns, well proposal a holographic hole. More generally, hope our identification several universal features spectroscopy provides useful starting point bottom-up holography astrophysical