Scalar superradiance in the charged black-bounce spacetimes

TL;DR

This paper numerically studies how a quantum parameter affects superradiance in charged black-bounce spacetimes, revealing suppression effects and new eigen-modes, with implications for black hole bomb models.

Contribution

It introduces the impact of a quantum parameter on superradiance and eigen-modes in charged black-bounce spacetimes, including novel findings in black hole bomb configurations.

Findings

Superradiance is weakened by the quantum parameter in scattering and bomb models.

A new eigen-mode appears in high quantum parameter regimes in Type I black hole bombs.

No amplification occurs for heavy fields in Type II black hole bomb configurations.

Abstract

We numerically investigate the superradiant amplification effect of a charged scalar filed in the scattering experiment and the black hole bomb model in a charged black-bounce spacetime. Due to the shallowing effect on the effective potential by the introduced quantum parameter $\l$, superradiance in both the above cases are verified to be weakened. In a scattering experiment, the quantum parameter and the field mass suppress the amplification in all frequency ranges, while the black hole and field charge influence it differently in high and low frequencies. In a Type I black hole bomb model, where the reflective mirror is placed outside the ergo-region, we find a new distinct eigen-mode for the scalar field evolution in a high $\l$ value, which is however absent in the case of Type II black bomb where the mirror is set inside the ergo-region. Moreover, we investigate the heavy field mass scenario in a Type II black hole bomb and find no amplification effect in this confined configuration.