Exotic compact object behavior in black hole analogues

Abstract

Classical phenomenological aspects of acoustic perturbations on a draining bathtub geometry where a surface with reflectivity $\mathcal{R}$ 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 $|\mathcal{R}{|}^2\approx 1$. However, stability can be attained for sufficiently slow drains when $|\mathcal{R}{|}^2\lesssim 70\%$. It is shown that the superradiant scattering of acoustic waves is more effective when their frequency approaches one of the system's quasi-normal mode frequencies.

12 pages, 6 figures. Accepted for publication as a Regular Article in Physical Review D

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Cited by in corpus (1)

• Acoustic black holes in curved spacetime and emergence of analogue Minkowski metric