Boson stars and solitons confined in a Minkowski box

Abstract

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-Nordström solution. The Israel junction conditions at the box surface layer determine the stress tensor that the box must have to confine the scalar hair. These horizonless hairy solutions exist for any value of the scalar field charge and not only above the natural critical charges of the theory (namely, the critical charges for the onset of the near-horizon and superradiant instabilities of the Reissner-Nordström black hole). However, the ground state solutions have a non-trivial intricate phase diagram with a main and a secondary family of solitons (some with a Chandrasekhar mass limit but others without) and there is a third critical scalar field charge where the soliton spectra changes radically. Most of these intricate properties are not captured by a higher order perturbative analysis of the problem.

Superradiance and black resonator strings encounter helical black strings

“…We pick up three particular solutions: the MPBS/helical string at the onset of instability for Ω H /Ω ext H = 0.89 (blue MPBS), and two helical black strings (orange HBS1, and green HBS2). Specifically, the HBH1 and HBH2 helical black strings 17 Black hole resonators that bifurcate from the onset of other superradiant systems (typically, in asymptotically AdS spaces [29, 33-35, 37, 60-62] or in asymptotically flat backgrounds with bound states confined by a massive scalar [63] or by a box [64][65][66]) also have a single branching family. The non-uniform strings that bifurcate from the Gregory-Laflamme onset also have this property [51,55,[57][58][59][67][68][69][70][71][72][73][74][75][76][77].…”