Research Repository

See what's under the surface


Quasi-normal modes and fermionic vacuum decay around a Kerr black hole (2019)
Journal Article
Coutant, A., & Millington, P. (2019). Quasi-normal modes and fermionic vacuum decay around a Kerr black hole. Classical and Quantum Gravity, 36(3), 035005. doi:10.1088/1361-6382/aaf679

We analyze the instability of the non-rotating fermion vacuum in Kerr spacetimes. We describe how the co-rotating Fermi sea is formed as a result of a spontaneous vacuum decay. Most significantly, and drawing upon intuition gained from analogous elec... Read More

Waves on a vortex: rays, rings and resonances (2018)
Journal Article
Torres, T., Coutant, A., Dolan, S., & Weinfurtner, S. (2018). Waves on a vortex: rays, rings and resonances. Journal of Fluid Mechanics, 857, 291-311. doi:10.1017/jfm.2018.752

We study the scattering of surface water waves with irrotational draining vortices. At small depth, this system is a mathematical analogue of a rotating black hole and can be used to mimic some of its peculiar phenomena. Using ray-tracing methods, we... Read More

Black hole quasibound states from a draining bathtub vortex flow (2018)
Journal Article
Patrick, S., Coutant, A., Richartz, M., & Weinfurtner, S. (2018). Black hole quasibound states from a draining bathtub vortex flow. Physical Review Letters, 121(6), doi:10.1103/physrevlett.121.061101. ISSN 0031-9007

Quasinormal modes are a set of damped resonances that describe how an excited open system is driven back to equilibrium. In gravitational physics these modes characterize the ringdown of a perturbed black hole, e.g., following a binary black hole mer... Read More

Low-frequency analogue Hawking radiation: The Bogoliubov-de Gennes model (2018)
Journal Article
Coutant, A., & Weinfurtner, S. (2018). Low-frequency analogue Hawking radiation: The Bogoliubov-de Gennes model. Physical Review D, 97(2), doi:10.1103/PhysRevD.97.025006. ISSN 2470-0010

We analytically study the low-frequency properties of the analogue Hawking effect in Bose-Einstein condensates. We show that in one-dimensional flows displaying an analogue horizon, the Hawking effect is dominant in the low-frequency regime. This hap... Read More

Low-frequency analogue Hawking radiation: the Korteweg–de Vries model (2018)
Journal Article
Coutant, A., & Weinfurtner, S. (2018). Low-frequency analogue Hawking radiation: the Korteweg–de Vries model. Physical Review D, 97(2), doi:10.1103/PhysRevD.97.025005. ISSN 2470-0010

We derive analytic expressions for the low-frequency properties of the analogue Hawking radiation in a general weak-dispersive medium. A thermal low-frequency part of the spectrum is expected even when dispersive effects become significant. We consid... Read More

Rotational superradiant scattering in a vortex flow (2017)
Journal Article
Torres, T., Patrick, S., Coutant, A., Richartz, M., Tedford, E. . W., & Weinfurtner, S. (2017). Rotational superradiant scattering in a vortex flow. Nature Physics, 13, doi:10.1038/nphys4151. ISSN 1745-2473

When an incident wave scatters off of an obstacle, it is partially reflected and partially transmitted. In theory, if the obstacle is rotating, waves can be amplified in the process, extracting energy from the scatterer. Here we describe in detail th... Read More

Detecting rotational superradiance in fluid laboratories (2016)
Journal Article
Cardoso, V., Coutant, A., Richartz, M., & Weinfurtner, S. (2016). Detecting rotational superradiance in fluid laboratories. Physical Review Letters, 117(27), doi:10.1103/PhysRevLett.117.271101. ISSN 0031-9007

Rotational superradiance was predicted theoretically decades ago, and is chiefly responsible for a number of important effects and phenomenology in black-hole physics. However, rotational superradiance has never been observed experimentally. Here, wi... Read More

The imprint of the analogue Hawking effect in subcritical flows (2016)
Journal Article
Coutant, A., & Weinfurtner, S. (2016). The imprint of the analogue Hawking effect in subcritical flows. Physical Review D, 94(6), doi:10.1103/PhysRevD.94.064026. ISSN 2470-0010

We study the propagation of low-frequency shallow water waves on a one-dimensional flow of varying depth. When taking into account dispersive effects, the linear propagation of long-wavelength modes on uneven bottoms excites new solutions of the disp... Read More