Quasi-normal mode analysis in BEC acoustic black holes

TL;DR

This paper investigates quasi-normal modes in Bose-Einstein condensate black hole analogs using the full Bogoliubov dispersion relation, revealing continuous spectra absent in hydrodynamic approximations.

Contribution

It demonstrates the existence of continuous quasi-normal mode spectra in BEC black hole analogs when considering the full dispersion relation, contrasting with hydrodynamic predictions.

Findings

Quasi-normal modes do not exist in hydrodynamic approximation.

Full dispersion relation reveals continuous quasi-normal mode spectrum.

Quasi-normal modes are present in BEC black hole configurations with step-like discontinuities.

Abstract

We perform a quasi-normal mode analysis of black hole configurations in Bose-Einstein condensates (BEC). In this analysis we use the full Bogoliubov dispersion relation, not just the hydrodynamic or geometric approximation. We restrict our attention to one-dimensional flows in BEC with step-like discontinuities. For this case we show that in the hydrodynamic approximation quasi-normal modes do not exist. The full dispersion relation, however, allows the existence of quasi-normal modes. Remarkably, the spectrum of these modes is not discrete but continuous.