Self-amplifying Hawking radiation and its background: a numerical study

TL;DR

This numerical study investigates an analogue black hole with two horizons, revealing the evolution of self-amplifying Hawking radiation on a background with a zero-frequency ripple, and clarifying its features and background dynamics.

Contribution

It demonstrates the existence of self-amplifying Hawking radiation on a complex background, distinguishing it from the background evolution and aligning with recent experimental observations.

Findings

Hawking radiation exists on a background with a zero-frequency ripple.

Self-amplifying Hawking radiation develops from spontaneous emission.

Background ripple appears before the inner horizon forms.

Abstract

We numerically study an analogue black hole with two horizons with similar parameters to a recent experiment. We find that the Hawking radiation exists on a background which contains a density oscillation, a zero-frequency ripple. The Hawking radiation evolves from spontaneous to self-amplifying, while the background ripple grows steadily with no qualitative change. It is seen that the self-amplifying Hawking radiation has a non-zero frequency. The background ripple appears even before the inner horizon is created, in contrast to predictions. This work is in agreement with the recent observation of self-amplifying Hawking radiation, and explains some of the features seen. In contrast to recent works, our study differentiates between the Hawking radiation observed, and the evolution of the background.