Boson stars and solitons confined in a Minkowski box

Understand

We consider the static charged black hole bomb system, originally designed for a (uncharged) rotating superradiant system by Press and Teukolsky.

• A charged scalar field confined in a Minkowski cavity with a Maxwell gauge field has a quantized spectrum of normal modes that can fit inside the box.
• Back-reacting non-linearly these normal modes, we find the hairy solitons, a.k.a boson stars (depending on the chosen $U(1)$ gauge), of the theory.
• The scalar condensate is totally confined inside the box and, outside it, we have the Reissner-Nordstr\"om solution.