Black Holes with Multiple Photon Spheres

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Recently, asymptotically-flat black holes with multiple photon spheres have been discovered and found to produce distinctive observational signatures.

• In this paper, we focus on whether these black hole solutions are physically viable, e.g., satisfying energy conditions of interest.
• Intriguingly, black hole and naked singularity solutions with two photon spheres and one anti-photon sphere are shown to exist in physically reasonable models, which satisfy the null, weak, dominant and strong energy conditions.
• Our findings reveal that black holes with multiple photon spheres may not be frequent, but they are not exotic.