On the robustness of acoustic black hole spectra

TL;DR

This paper investigates how the emission spectrum of an acoustic black hole in Bose--Einstein condensates remains stable under flow variations, revealing the spectrum's robustness until the horizon vanishes, with new phenomena emerging in fully supersonic flows.

Contribution

It demonstrates the spectral robustness of acoustic black holes with superluminal dispersion until the horizon disappears, and identifies new pair creation channels in fully supersonic flows.

Findings

Spectrum remains Planckian until horizon disappears

New pair creation channels open in fully supersonic flows

Robustness of black hole spectra under flow variations

Abstract

We study the robustness of the spectrum emitted by an acoustic black hole by considering series of stationary flows that become either subsonic or supersonic, i.e. when the horizon disappears. We work with the superluminal Bogoliubov dispersion of Bose--Einstein condensates. We find that the spectrum remains remarkably Planckian until the horizon disappears. When the flow is everywhere supersonic, new pair creation channels open. This will be the subject of a forthcoming work.