Phase diagrams of the boson stars and shells of the $U(1)$ gauged $\mathbb{C}{P}^N$ nonlinear sigma model are studied. The solutions of the model exhibit both the ball- and the shell-shaped charge density depending on $N$. There appear four independent regions of the solutions which are essentially caused from the coexistence of electromagnetism and gravity. We examine several phase diagrams of the boson stars and the shells and discuss what and how the regions are emerged. A coupling with gravity allows for harboring of the charged black holes for the $Q$-shell solutions. Some solutions are strongly affected by the presence of the black holes and they allow to be smoothly connected. As a result, the regions are integrated by the harboring black holes.

• Received 17 March 2021
• Accepted 7 April 2021

DOI:https://doi.org/10.1103/PhysRevD.103.125018

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Published by the American Physical Society