paper

Extremal Charged Black Holes and Superradiantly Unstable Quasinormal Modes

arXiv:2201.11138 · doi:10.1140/epjc/s10052-022-10490-y

Abstract

It was recently shown that the extremal charged black holes in STU supergravity suffer from superradiant instability owing to the existence of the unstable (low-frequency) quasibound states associated with a charged massive scalar field. In this paper, we show numerically that for some charge configurations, these black holes can also excite the (higher-frequency) superradiantly unstable quasinormal modes. We find empirically that the unstable modes are closely related to having a volcano-shaped effective potential in the Schrödinger-like wave equation.

17 pages, 11 graphs grouped into 5 figures, typos corrected, comments added and refences updated, to appear in EPJC

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