The Quasinormal Modes of Quasinormal Modes

Understand

Modifying black hole horizon can drastically change the spectrum of quasinormal modes.

• But if the modification is close enough to the horizon the ringdown signal remains almost unaltered, and well described by the quasinormal modes of the original GR solution.
• I show how the original quasinormal modes emerge in the sum over the new modes.