Resonant Hawking radiation as an instability

TL;DR

This paper models a black-hole laser using a Bose-Einstein condensate with horizons, demonstrating that it exhibits laser-like instabilities and emits both Hawking and trans-Planckian radiation.

Contribution

It introduces a simple model for black-hole lasers showing how instabilities lead to radiation emission, including trans-Planckian tunneling effects.

Findings

Black-hole laser exhibits discrete unstable modes.

Amplification of waves between horizons mimics laser cavity behavior.

Trans-Planckian radiation tunnels out of the system.

Abstract

We consider a simple model for a black-hole laser: a Bose-Einstein condensate with uniform speed of sound and partially uniform flow, establishing two horizons, a black-hole and a white-hole horizon. Waves confined between the horizons are amplified similar to radiation in a laser cavity. Black-hole lasing appears as an instability with discrete sets of modes given approximately by a round-trip condition. We found that, in addition to the regular Hawking radiation, trans-Planckian radiation does tunnel out of the black-hole laser.