Superradiance or total reflection?

Understand

Numerical evolution of massless scalar fields on Kerr background is studied.

• The initial data specifications are chosen to have compact support separated from the ergoregion and to yield nearly monochromatic incident wave packets.
• The initial data is also tuned to maximize the effect of superradiance.
• Evidences are shown indicating that instead of the anticipated energy extraction from black hole the incident radiation fail to reach the ergoregion rather it suffers a nearly perfect reflection.