Ergoregion instability in a fluid with vorticity

TL;DR

This paper explores how vorticity affects ergoregion instability in a rotating, incompressible fluid, revealing that vorticity reduces the instability through numerical analysis of quasinormal modes.

Contribution

It provides the first detailed numerical study of the impact of vorticity on ergoregion instability in fluid analogs of black holes.

Findings

Vorticity diminishes the ergoregion instability.

Two numerical methods show excellent agreement.

The study advances understanding of fluid analogs to black hole phenomena.

Abstract

We investigate perturbations in a rotational and incompressible fluid flow. Interested in the phenomenon analogous to the black hole ergoregion instability, we verify the influence of the vorticity in the instability associated with this fluid system, in the presence of a region in which the fluid flow velocity is greater than the speed of the perturbation. With this aim, we compute the quasinormal modes of the system, using two different numerical methods, obtaining an excellent numerical agreement between them. We find that the vorticity tends to diminish the ergoregion instability of the system.