Quasinormal modes of the BTZ black hole under scalar perturbations with a non-minimal coupling: Exact spectrum

Understand

We perturb the non-rotating BTZ black hole with a non-minimally coupled massless scalar field, and we compute the quasinormal spectrum exactly.

• We solve the radial equation in terms of hypergeometric functions, and we obtain an analytical expression for the quasinormal frequencies.
• In addition, we compare our analytical results with the 6th order semi-analytical WKB method, and we find an excellent agreement.
• The impact of the nonminimal coupling as well as of the cosmological constant on the quasinormal spectrum is briefly discussed.