Infinitesimally thin static scalar shells surrounding charged Gauss-Bonnet black holes

We reveal the existence of a new form of spontaneously scalarized black-hole configurations. In particular, it is proved that Reissner-Nordstrom black holes in the highly charged regime Q/M > (Q/M)(crit) = root 21/5 can support thin matter shells that are made of massive scalar fields with a non-minimal coupling to the Gauss-Bonnet invariant of the curved spacetime. These static scalar shells, which become infinitesimally thin in the dimensionless large-mass M mu >> 1 regime, hover a finite proper distance above the black-hole horizon [here {M, Q} are respectively the mass and electric charge of the central supporting black hole, and mu is the proper mass of the supported scalar field]. In addition, we derive a remarkably compact analytical formula for the discrete resonance spectrum {eta(Q/M, M mu; n)}(n=0)(n=infinity )of the non-trivial coupling parameter which characterizes the bound-state charged-black-hole-thin-massive-scalar-shell cloudy configurations of the composed Einstein-Maxwell-scalar field theory.

Automated summary

The study reveals the existence of a new form of spontaneously scalarized black-hole configurations, showing that highly charged Reissner-Nordstrom black holes can support thin matter shells made of massive scalar fields. A compact analytical formula for the resonance spectrum of the coupling parameter characterizing the bound-state charged-black-hole-thin-massive-scalar-shell cloudy configurations is derived. These static scalar shells can hover a finite distance above the black-hole horizon under certain conditions.