Quasinormal modes of black holes and Borel summation

Understand

We propose a simple and efficient way to compute quasinormal frequencies of spherically symmetric black holes.

• We revisit an old idea that relates them to bound state energies of anharmonic oscillators by an analytic continuation.
• This connection enables us to achieve remarkable high-order computations of WKB series by Rayleigh-Schr\"odinger perturbation theory.
• The known WKB results are easily reproduced.