Rotating black holes in a draining bathtub: superradiant scattering of gravity waves

Abstract

In a draining rotating fluid flow background, surface perturbations behave as a scalar field on a rotating effective black hole spacetime. We propose a new model for the background flow which takes into account the varying depth of the water. Numerical integration of the associated Klein-Gordon equation using accessible experimental parameters shows that gravity waves in an appropriate frequency range are amplified through the mechanism of superradiance. Our numerical results suggest that the observation of this phenomenon in a common fluid mechanical system is within experimental reach. Unlike the case of wave scattering around Kerr black holes, which depends only on one dimensionless background parameter (the ratio $a/M$ between the specific angular momentum and the mass of the black hole), our system depends on two dimensionless background parameters, namely the normalized angular velocity and surface gravity at the effective black hole horizon.

v3: 13 pages, 4 figures. Revised version with minor updates and journal reference

References in corpus (6)

• Fiber-optical analogue of the event horizon
• Measurement of stimulated Hawking emission in an analogue system
• Observation of self-amplifying Hawking radiation in an analog black hole laser
• Hawking radiation from ultrashort laser pulse filaments
• Observation of negative-frequency waves in a water tank: A classical analogue to the Hawking effect?
• Experimental demonstration of the supersonic-subsonic bifurcation in the circular jump: A hydrodynamic white hole

Cited by in corpus (17)

• Detecting Rotational Superradiance in Fluid Laboratories
• Slowly-rotating curved acoustic black holes: Quasinormal modes, Hawking-Unruh radiation and quasibound states
• Analog Schwarzschild black holes of Bose-Einstein condensates in a cavity: Quasinormal modes and quasibound states
• Analogue gravity and the Hawking effect: historical perspective and literature review
• Understanding superradiant phenomena with synthetic vector potentials in atomic Bose-Einstein condensates
• Superradiance in dispersive black hole analogues
• AdS and dS black hole solutions in analogue gravity: The relativistic and non-relativistic cases
• Analogue Quantum Simulation: A New Instrument for Scientific Understanding
• Perturbing the vortex: quasinormal and quasibound spectra of rotating acoustic geometries
• Analogue model for anti-de Sitter as a description of point sources in fluids
• Rotational superradiance with Bogoliubov dispersion
• Imperfect draining vortex as analogue extreme compact object
• Dispersive censor of acoustic spacetimes with a shock-wave singularity
• Vortices without inflow: bound spectra in horizonless rotational analogs
• Mimicking a rotating black hole with nonlinear electrodynamics
• Quasibound states of analytic black-hole configurations in three and four dimensions
• On the analogy between black holes and bathtub vortices