Sensitivity of Hawking radiation to superluminal dispersion relations

TL;DR

This paper investigates how superluminal modifications to dispersion relations affect Hawking radiation during gravitational collapse, revealing significant qualitative and quantitative changes in the radiation spectrum.

Contribution

It demonstrates that superluminal dispersion relations cause the horizon to become frequency-dependent, leading to altered Hawking radiation spectra with measurable effects.

Findings

Radiation spectrum depends on measurement time and frequency

Significant modifications occur even with critical frequencies above the Planck scale

Horizon becomes a frequency-dependent concept due to superluminal dispersion

Abstract

We analyze the Hawking radiation process due to collapsing configurations in the presence of superluminal modifications of the dispersion relation. With such superluminal dispersion relations, the horizon effectively becomes a frequency-dependent concept. In particular, at every moment of the collapse, there is a critical frequency above which no horizon is experienced. We show that, as a consequence, the late-time radiation suffers strong modifications, both quantitative and qualitative, compared to the standard Hawking picture. Concretely, we show that the radiation spectrum becomes dependent on the measuring time, on the surface gravities associated with different frequencies, and on the critical frequency. Even if the critical frequency is well above the Planck scale, important modifications still show up.