Gravitational decoupling and aerodynamics: black holes and analog gravity in a jet propulsion lab

A connection is established between transonic sound waves propagating along a de Laval nozzle and quasi- normal modes emitted from hairy black holes obtained with the gravitational decoupling method applied to the Reissner– Nordström geometry. Aerodynamical features provide an analogue setup to test experimentally perturbations of fluid flows in a de Laval nozzle producing quasinormal modes. In particular, nozzle shape, pressure, Mach number, tempera- ture, density, and thrust coefficient profiles are determined as functions of the black hole parameters for several multi- pole numbers. The black hole quasinormal mode frequencies are also investigated for different overtones, evaluating the quality factor of the nozzle.