Island in Charged Black Holes

We study the information problem in the eternal black hole with charges on a doubly-holographic model in general dimensions, where the charged black hole on a Planck brane is coupled to the bath on the conformal boundary. For a brane with weak tension, its backreaction to the bulk is negligible and the entropy of the radiation is dominated by the entanglement entropy of the matter. We analytically calculate the entropy of the radiation and obtain the Page-like curve with the presence of an island on the brane. The Page time is evaluated as well. For a brane with strong tension, we obtain the numerical solution with backreaction in four-dimensional space time and find the quantum extremal surface at $t=0$. It turns out that the geometric entropy related to the area term on the brane postpones the Page time.