Analytic treatment of the black-hole bomb

Understand

A bosonic field impinging on a rotating black hole can be amplified as it scatters off the hole, a phenomena known as superradiant scattering.

• If in addition the field has a non-zero rest mass then the mass term effectively works as a mirror, reflecting the scattered wave back towards the black hole.
• In this physical system, known as a black-hole bomb, the wave may bounce back and forth between the black hole and some turning point amplifying itself each time.
• Consequently, the massive field grows exponentially over time and is unstable.