Superradiance in Kerr-like black holes

Understand

Recent strong-field regime tests of gravity are so far in agreement with general relativity.

• In particular, astrophysical black holes appear all to be consistent with the Kerr spacetime, but the statistical error on current observations allows for small yet detectable deviations from this description.
• Here we study superradiance of scalar and electromagnetic test fields around the Kerr-like Konoplya--Zhidenko black hole and we observe that for large values of the deformation parameter superradiance is highly suppressed with respect to the Kerr case.
• Surprisingly, there exists a range of small values of the deformation parameter for which the maximum amplification factor is larger than the Kerr one.