The role of topological photon spheres in constraining the parameters of black holes

• Published in: Astroparticle physics Vol. 162; p. 102994
• Main Authors: Sadeghi, Jafar, Afshar, Mohammad Ali S.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.10.2024
• Subjects: Black hole; Parameters of black hole; Photon sphere; Topological classification; Black hole; Topological classification; Photon sphere; Parameters of black hole
• ISSN: 0927-6505; 1873-2852
• DOI: 10.1016/j.astropartphys.2024.102994

In this paper, we investigate the topological photon sphere from two distinct perspectives. In the first view, we examine the existence and characteristics of topological photon (anti-photon) spheres for black holes with different structures, such as Einstein–Young–Mills non-minimal, AdS black holes surrounded by Chaplygin-like dark fluid, and Bardeen-like black holes in Einstein–Gauss–Bonnet gravity. Furthermore, we delve into the deeper perspective of the necessity of photon spheres for super-compact gravitational structures such as black holes. By leveraging this necessity, we propose a classification of the parameter space of black hole models based on the existence and positioning of photon spheres. This approach enables the determination of parameter ranges that delineate whether a solution represents a black hole or a naked singularity. In essence, the paper illustrates the utility of the photon sphere as a notable test for establishing the permissible and non-permissible parameter ranges within specific theories of black hole solutions.