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

Richartz, Mauricio; Prain, Angus; Liberati, Stefano; Weinfurtner, Silke

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.

Citation

Richartz, M., Prain, A., Liberati, S., & Weinfurtner, S. (2015). Rotating black holes in a draining bathtub: superradiant scattering of gravity waves. Physical Review D, 91(12), Article 124018. https://doi.org/10.1103/PhysRevD.91.124018

• Journal Article Type: Article
• Acceptance Date: May 13, 2015
• Publication Date: Jun 5, 2015
• Deposit Date: May 9, 2017
• Publicly Available Date: May 9, 2017
• Journal: Physical Review D
• Print ISSN: 2470-0010
• Electronic ISSN: 2470-0029
• Publisher: American Physical Society
• Peer Reviewed: Peer Reviewed
• Volume: 91
• Issue: 12
• Article Number: 124018
• DOI: https://doi.org/10.1103/PhysRevD.91.124018
• Public URL: https://nottingham-repository.worktribe.com/output/755145
• Publisher URL: https://doi.org/10.1103/PhysRevD.91.124018
• Additional Information: © 2015 American Physical Society
• Contract Date: May 9, 2017