• [1]

    K. Akiyama et al., Astrophys. J. Lett. 875, L1 (2019), arXiv:1906.11238

  • [2]

    K. Akiyama et al., Array and Instrumentation. Astrophys. J. Lett. 875(1), L2 (2019), arXiv:1906.11239

  • [3]

    K. Akiyama et al., Data Processing and Calibration. Astrophys. J. Lett. 875(1), L3 (2019), arXiv:1906.11240

  • [4]

    K. Akiyama et al., Astrophys. J. Lett. 875(1), L4 (2019), arXiv:1906.11241

  • [5]

    K. Akiyama et al., Astrophys. J. Lett. 875(1), L5 (2019), arXiv:1906.11242

  • [6]

    K. Akiyama et al., Astrophys. J. Lett. 875(1), L6 (2019), arXiv:1906.11243

  • [7]

    K. Akiyama et al., Astrophys. J. Lett. 910(1), L12 (2021), arXiv:2105.01169

  • [8]

    K. Akiyama et al., Astrophys. J. Lett. 910(1), L13 (2021), arXiv:2105.01173

  • [9]

    K. Akiyama et al., Astrophys. J. Lett. 930(2), L12 (2022), arXiv:3847/2041-8213/ac6674

  • [10]

    K. Akiyama et al., Astrophys. J. Lett. 930(2), L13 (2022), arXiv:3847/2041-8213/ac6675

  • [11]

    K. Akiyama et al., Astrophys. J. Lett. 930(2), L14 (2022), arXiv:3847/2041-8213/ac6429

  • [12]

    K. Akiyama et al., Astrophys. J. Lett. 930(2), L15 (2022), arXiv:3847/2041-8213/ac6736

  • [13]

    K. Akiyama et al., Astrophys. J. Lett. 930(2), L16 (2022), arXiv:3847/2041-8213/ac6672

  • [14]

    K. Akiyama et al., Astrophys. J. Lett. 930(2), L17 (2022), arXiv:3847/2041-8213/ac6756.I

  • [15]

    C. M. Will, Living Rev. Rel. 17, 4 (2014), arXiv:1403.7377

  • [16]

    Roy P. Kerr, Phys. Rev. Lett. 11, 237 (1963), arXiv:1103/PhysRevLett.11.237.I

  • [17]

    R. Penrose, Phys. Rev. Lett. 14, 57 (1965)

  • [18]

    J. L. Synge, Mon. Not. Roy. Astron. Soc. 131(3), 463 (1966), arXiv:1093/mnras/131.3.463.I

  • [19]

    J. M. Bardeen, W. H. Press, and S. A. Teukolsky, Astrophys. J. 178, 347 (1972), arXiv:1086/151796

  • [20]

    J. M. Bardeen, Timelike and null geodesics in the Kerr metric, In Les Houches Summer School of Theoretical Physics: Black Holes, 1973

  • [21]

    K. S. Virbhadra and G. F. R. Ellis, Phys. Rev. D 62, 084003 (2000), arXiv:astro-ph/9904193

  • [22]

    C.-M. Claudel, K. S. Virbhadra, and G. F. R. Ellis, J. Math. Phys. 42, 818 (2001), arXiv:gr-qc/0005050

  • [23]

    K. S. Virbhadra, Phys. Rev. D 79, 083004 (2009), arXiv:0810.2109

  • [24]

    Valerio Bozza, Gen. Rel. Grav. 42, 2269 (2010), arXiv:0911.2187

  • [25]

    K. S. Virbhadra, Phys. Rev. D 106(6), 064038 (2022), arXiv:2204.01879

  • [26]

    F. Schmidt, Phys. Rev. D 78, 043002 (2008), arXiv:0805.4812

  • [27]

    J. Guzik, Phys. Rev. D 81, 023503 (2010), arXiv:0906.2221

  • [28]

    K. Liao, Z. Li, S. Cao et al., Astrophys. J. 822(2), 74 (2016), arXiv:1511.01318

  • [29]

    P. Goulart, Class. Quant. Grav. 35(2), 025012 (2018), arXiv:1708.00935

  • [30]

    J. R. Nascimento, A. Yu. Petrov, P. J. Porfirio et al., Phys. Rev. D 102(4), 044021 (2020), arXiv:2005.13096

  • [31]

    S. UI Islam, J. Kumar, and S. G. Ghosh, JCAP 10, 013 (2021), arXiv:2104.00696

  • [32]

    N. Tsukamoto, Phys. Rev. D 104(6), 064022 (2021), arXiv:2105.14336

  • [33]

    H. C. D. Lima Junior, J.-Z. Yang, L. C. B. Crispino et al., Phys. Rev. D 105(6), 064070 (2022), arXiv:2112.10802

  • [34]

    G. J. Olmo, D. Rubiera-Garcia, and D. S.-C. Gómez, Phys. Lett. B 829, 137045 (2022), arXiv:2110.10002

  • [35]

    S. Ghosh and A. Bhattacharyya, JCAP 11, 006 (2022), arXiv:2206.09954

  • [36]

    D. Ayzenberg et al., arXiv: 2312.02130 [astro-ph.HE]

  • [37]

    S. L. Shapiro and S. A. Teukolsky, Phys. Rev. Lett. 66, 994 (1991), arXiv:1103/PhysRevLett.66.994.I

  • [38]

    P. S. Joshi and I. H. Dwivedi, Phys. Rev. D 47, 5357 (1993), arXiv:gr-qc/9303037

  • [39]

    T. Harada, H. Iguchi, and K.-i. Nakao, Phys. Rev. D 58, 041502 (1998), arXiv:gr-qc/9805071

  • [40]

    P. S. Joshi, N. Dadhich, and R. Maartens, Phys. Rev. D 65, 101501 (2002), arXiv:gr-qc/0109051

  • [41]

    R. Goswami and P. S. Joshi, Phys. Rev. D 76, 084026 (2007), arXiv:gr-qc/0608136

  • [42]

    N. Banerjee and S. Chakrabarti, Rev. D 95(2), 024015 (2017), arXiv:1701.04235

  • [43]

    K. Bhattacharya, D. Dey, A. Mazumdar et al., Phys. Rev. D 101(4), 043005 (2020), arXiv:1709.03798

  • [44]

    J. Wagner, arXiv: 2301.13210 [astro-ph.CO]

  • [45]

    K. S. Virbhadra and G. F. R. Ellis, Phys. Rev. D 65, 103004 (2002), arXiv:1103/PhysRevD.65.103004.I

  • [46]

    K. S. Virbhadra and C. R. Keeton, Phys. Rev. D 77, 124014 (2008), arXiv:0710.2333

  • [47]

    G. N. Gyulchev and S. S. Yazadjiev, Phys. Rev. D 78, 083004 (2008), arXiv:0806.3289

  • [48]

    S. Sahu, M. Patil, D. Narasimha et al., Phys. Rev. D 86, 063010 (2012), arXiv:1206.3077

  • [49]

    R. Shaikh, P. Banerjee, S. Paul et al., Phys. Rev. D 99(10), 104040 (2019), arXiv:1903.08211

  • [50]

    S. Paul, Phys. Rev. D 102(6), 064045 (2020), arXiv:2007.05509

  • [51]

    V. I. Zhdanov and O. S. Stashko, Phys. Rev. D 101(6), 064064 (2020), arXiv:1912.00470

  • [52]

    O. S. Stashko, V. I. Zhdanov, and A. N. Alexandrov, Phys. Rev. D 104(10), 104055 (2021), arXiv:2107.05111

  • [53]

    O. Stashko and V. I. Zhdanov, Galaxies 9(4), 72 (2021), arXiv:2109.01931

  • [54]

    N. Tsukamoto, Phys. Rev. D 104(12), 124016 (2021), arXiv:2107.07146

  • [55]

    M. Wang, G. Guo, P. Yan et al., arXiv: 2307.16748 [gr-qc]

  • [56]

    Y. Chen, P. Wang, H. Wu et al., arXiv: 2305.17411 [gr-qc]

  • [57]

    J. Dexter et al., Mon. Not. Roy. Astron. Soc. 497(4), 4999 (2020), arXiv:2006.03657

  • [58]

    N. Scepi, J. Dexter, and M. C. Begelman, Mon. Not. Roy. Astron. Soc. 511(3), 3536 (2022), arXiv:2107.08056

  • [59]

    I. EI Mellah, B. Cerutti, B. Crinquand et al., Astron. Astrophys. 663, A169 (2022), arXiv:2112.03933

  • [60]

    G. Witzel et al., Astrophys. J. 917(2), 73 (2021), arXiv:2011.09582

  • [61]

    J. M. Michail, M. Wardle, F. Yusef-Zadeh et al., Astrophys. J. 923(1), 54 (2021), arXiv:2107.09681

  • [62]

    R. Abuter et al., Astron. Astrophys. 654, A22 (2021), arXiv:2107.01096

  • [63]

    M. Wielgus, M. Moscibrodzka, J. Vos et al., Astron. Astrophys. 665, L6 (2022), arXiv:2209.09926

  • [64]

    N. Hamaus, T. Paumard, T. Muller et al., Astrophys. J. 692, 902 (2009), arXiv:0810.4947

  • [65]

    R. Abuter et al. (GRAVITY Collaboration), Astron. Astrophys. 618, L10 (2018)

  • [66]

    Jo?ao Luís Rosa, Paulo Garcia, Frédéric H. Vincent, and Vitor Cardoso, Phys. Rev. D 106(4), 044031 (2022), arXiv:2205.11541

  • [67]

    J. L. Rosa, C. F. B. Macedo, and D. Rubiera-Garcia, Phys. Rev. D 108(4), 044021 (2023), arXiv:2303.17296

  • [68]

    H. L. Tamm and J. L. Rosa, Phys. Rev. D 109, 044062 (2023)

  • [69]

    J. L. Rosa, D. S. J. Cordeiro, C. F. B. Macedo et al., Phys. Rev. D 109, 084002 (2023)

  • [70]

    D. Pugliese, H. Quevedo, and R. Ruffini, Phys. Rev. D 83, 024021 (2011), arXiv:1012.5411

  • [71]

    D. Pugliese, H. Quevedo, and R. Ruffini, Phys. Rev. D 83, 104052 (2011), arXiv:1103.1807

  • [72]

    D. Chen, Y. Chen, P. Wang et al., arXiv: 2309.00905 [gr-qc]

  • [73]

    S. Trippe, T. Paumard, T. Ott et al., Mon. Not. Roy. Astron. Soc. 375, 764 (2007), arXiv:astro-ph/0611737

  • [74]

    A. E. Broderick and A. Loeb, Mon. Not. Roy. Astron. Soc. 367, 905 (2006), arXiv:astro-ph/0509237

  • [75]

    Y. Chen, P. Wang, and H. Yang, arXiv: 2309.04157 [gr-qc]

  • [76]

    L. I. Gurvits et al., Exper. Astron. 51(3), 559 (2021), arXiv:1908.10767

  • [77]

    L. I. Gurvits et al., Acta Astronaut. 196, 314 (2022), arXiv:2204.09144

  • [78]

    S. S. Doeleman et al., Galaxies 11(5), 107 (2023), arXiv:2306.08787