Abstract
Classical phenomenological aspects of acoustic perturbations on a draining bathtub geometry where a surface with a reflectivity is set at a small distance from the would-be acoustic horizon, which is excised, are addressed. Like most exotic compact objects featuring an ergoregion but not a horizon, this model is prone to instabilities when . However, stability can be attained for sufficiently slow drains when . It is shown that the superradiant scattering of acoustic waves is more effective when their frequency approaches one of the system’s quasinormal mode frequencies.
- Received 26 February 2019
DOI:https://doi.org/10.1103/PhysRevD.99.084029
© 2019 American Physical Society