https://doi.org/10.1140/epjc/s10052-020-08570-y
Regular Article – Theoretical Physics
Tidal-charge effects on the superradiance of rotating black holes
Faculdade de Física, Universidade Federal do Pará, 66075-110, Belém, Pará, Brazil
Received:
1
July
2020
Accepted:
16
October
2020
Published online:
12
November
2020
The changes a (negative) tidal charge causes at the phenomenon of superradiance which occurs around rotating black holes are investigated. This is made by computing the amplification factors of massless scalar waves being scattered by the black hole. It is shown that the increase of the tidal-charge intensity leads to a considerable enhancement of energy extraction from near-extreme black holes. Such improvement results from the fact that extreme black holes with more negative tidal charges spin faster. Maximum amplification decreases with the increase of the tidal charge intensity if the angular momentum of the black hole per unit mass is fixed. The tidal charge may also change crucially the superradiance phenomenon of massless scalar waves causing maximum amplification to occur for 
differently from the case of Kerr black holes.
© The Author(s) 2020
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