Quasinormal modes in Lorentz violating black hole analogues

TL;DR

This paper explores how Lorentz symmetry violations in black hole analogue models affect quasinormal modes, revealing significant changes in mode frequencies and decay rates, especially under superluminal modifications.

Contribution

It provides a detailed analysis of the impact of Lorentz violations on quasinormal modes in draining vortex black hole analogues, highlighting new behaviors under sub- and superluminal dispersion modifications.

Findings

Co-rotating mode frequencies and decay rates are significantly altered by Lorentz violations.

Superluminal modifications eliminate certain quasinormal modes above or below critical rotations.

Counter-rotating modes are minimally affected by Lorentz violations.

Abstract

Analogue models of black holes typically have collective excitations with a dispersion relation that breaks the effective Lorentz symmetry at high energy. We investigate the consequences of such Lorentz violations on the quasinormal modes (QNMs) of the system, that is, the modes of energy dissipation. The model involves low frequency capillary-gravity waves (whose dispersion relation can be adjusted between sub- and superluminal modifications) around a draining vortex, which mimics a rotating black hole spacetime. For a subluminal/superluminal modification, the frequency and decay rate of co-rotating modes can be reduced/increased substantially, whilst counter-rotating modes are barely affected. A further consequence of the superluminal modification is that there are no corotating QNMs above a critical rotation and no counter-rotating ones below a critical rotation for strong enough Lorentz violations.