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Abstract
This article presents a comprehensive analysis of the optical properties of axially symmetric black holes, including photon motion, photon spheres, gravitational lensing, and the formation of black hole shadows. Within the framework of General Relativity, the Kerr solution is considered alongside alternative approaches such as the Kerr–Sen metric, γ-metric, rotating regular black holes, Finsler extensions, Rastall gravity theory, Einstein–Maxwell–Dilaton–Axion (EMDA) gravity, and Quantum Einstein Gravity (QEG). Particular attention is devoted to observable quantities, including the average shadow radius RsR_sRs, distortion parameter δs\delta_sδs, photon deflection angle α^\hat{\alpha}α^, as well as relativistic images and time delays in the strong-field regime. Constraints on axially symmetric spacetime parameters are obtained through comparison with observational results from the Event Horizon Telescope (EHT) for M87* and Sgr A*. The results demonstrate that the spin parameter and additional spacetime quantities significantly influence the shape and size of the black hole shadow, making them powerful tools for testing gravitational theories in strong gravity regimes.
References
[1] EHT Collaboration, Astrophys. J. Lett. 875, L1 (2019).
[2] EHT Collaboration, Astrophys. J. Lett. 930, L12 (2022).
[3] V. P. Frolov, I. D. Novikov, Black Hole Physics, Springer (1998).
[4] B. Narzilloev et al., Eur. Phys. J. Plus 137, 645 (2022).
[5] G. N. Gyulchev, S. S. Yazadjiev, Phys. Rev. D 81, 023005 (2010).
[6] A. B. Abdikamalov et al., Phys. Rev. D 100, 024014 (2019).
[7] F. Ahmed et al., Eur. Phys. J. C 85, 795 (2025).
[8] P. Rastall, Phys. Rev. D 6, 3357 (1972).
[9] K. Hioki, K. Maeda, Phys. Rev. D 80, 024042 (2009).
[10] X. Li et al., Phys. Rev. D 109, 064049 (2024).
[11] V. Vertogradov, A. Övgün, R. C. Pantig, arXiv:2405.05077 (2024).
[12] K. Salehi, A. E. Broderick, B. Georgiev, Astrophys. J. 960, 143 (2024).
[13] C.-H. Xie et al., JCAP 05, 121 (2024).
[14] S. K. Sahoo, N. Yadav, I. Banerjee, Phys. Rev. D 109, 044008 (2024).
[15] X. Xu et al., arXiv:2409.03975 (2024).
[16] M. Shahzadi et al., Phys. Dark Universe 46, 101599 (2024).
[17] R. Shaikh et al., Eur. Phys. J. C 82, 696 (2022).
[18] S. Vagnozzi et al., arXiv:2408.03241 (2024).
[19] A. Övgün et al., Eur. Phys. J. C 84, 1240 (2024).
[20] H. Jia, E. Quataert, Bull. AAS 56(2), 339.07 (2024).
[21] A. E. Broderick et al., Proc. SPIE (2024).
[22] V. Bozza, Phys. Rev. D 66, 103001 (2002).
[23] A. A. Araújo Filho et al., arXiv:2411.04674 (2024).