Black hole lasers

TL;DR

This paper investigates how superluminal dispersion in black hole analogs with inner and outer horizons causes exponential growth or suppression of Hawking radiation, revealing new dynamical effects beyond standard predictions.

Contribution

It demonstrates that superluminal dispersion with an inner horizon leads to significant modifications of Hawking radiation, including exponential growth or damping, unlike the standard effect.

Findings

Superluminal dispersion causes exponential growth or damping of Hawking radiation.

Negative energy partners return to the outer horizon, affecting radiation.

Observable effects may occur in condensed matter black hole analogs.

Abstract

High frequency dispersion does not alter the low frequency spectrum of Hawking radiation from a single black hole horizon, whether the dispersion entails subluminal or superluminal group velocities. We show here that in the presence of an inner horizon as well as an outer horizon the superluminal case differs dramatically however. The negative energy partners of Hawking quanta return to the outer horizon and stimulate more Hawking radiation if the field is bosonic or suppress it if the field is fermionic. This process leads to exponential growth or damping of the radiated flux and correlations among the quanta emitted at different times, unlike in the usual Hawking effect. These phenomena may be observable in condensed matter black hole analogs that exhibit "superluminal" dispersion.