Nonlinear self-interaction induced black hole bomb

We present the first alternative mechanisms to trigger black hole bomb phenomena beyond the famous superradiant instability. By incorporating nonlinear self-interaction into the massive charged scalar field in general relativity, we discover that the allowed static solutions suggest two such novel dynamic mechanisms, which are further confirmed by our numerical simulations. The first originates from a linearly unstable hairy black hole, but the bomb can be avoided by dialing the coefficient of the tiny scalar pulse. This distinguishes it from superradiant instability, where the bomb is an inevitable destiny. The second is an intrinsically nonlinear process, which can even drive a linearly stable Reissner-Nordstr"om black hole to become a black hole bomb by releasing substantial energy to develop scalar hair. This is also in sharp contrast with superradiant instability, which can only drive an unstable black hole. These findings not only open up new avenues for black hole energy bursts, but also have potential implications for new phenomena occurring around astrophysical black holes.