Circular orbits and observational signatures in regular black hole spacetimes
Errehymy A. Mustafa G. Rasheed A.S. Boshkayev K. Maurya S.K. Alessa N. Abdel-Aty A.-H.
24 October 2025World Scientific
International Journal of Geometric Methods in Modern Physics
2025#23Issue 2
Investigating the motion of matter near black holes (BHs) provides a powerful avenue to probe the extremes of gravity and the foundational properties of spacetime. This study explores in detail the motion of test particles in the vicinity of a static, spherically symmetric regular BH, defined by two key parameters: the mass M and a spacetime deformation factor β. Through an effective potential approach, we derive exact analytical expressions for the energy and angular momentum of particles on circular orbits, revealing how orbital stability is influenced by deviations from the Schwarzschild geometry. Our analysis encompasses the innermost stable circular orbits (ISCOs) and the associated dynamical forces acting on test particles, offering critical insights into the structure of the BH’s near-horizon geometry. We extend our analysis to the numerical integration of the geodesic equations, revealing intricate orbital structures such as epicyclic motion confined to the equatorial plane. Additionally, we derive closed-form expressions for the radial, vertical, and orbital frequencies, all expressed explicitly in terms of the deformation parameter β, allowing for direct confrontation with observational QPO data. We also investigate the periastron precession frequency and demonstrate how these frequency modes may serve as observational probes of the underlying spacetime. Finally, we analyze particle collisions near the event horizon, calculating the center-of-mass energy to assess the potential for high-energy interactions in regular BH environments. These results offer a unified framework for connecting BH geometry, particle dynamics, and QPO observables, advancing our understanding of both theoretical and astrophysical aspects of regular BHs.
circular orbits , particle motion , QPOs , Regular BH
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Astrophysics Research Centre, University of KwaZulu-Natal, School of Mathematics Statistics and Computer Science, Private Bag X54001, Durban, 4000, South Africa
Center for Theoretical Physics, Khazar University, 41 Mehseti Str., Baku, AZ1096, Azerbaijan
Department of Physics, Zhejiang Normal University, Jinhua, 321004, China
Department of Physics, Babeş-Bolyai University, Kogălniceanu Street, Cluj-Napoca, 400084, Romania
Ministry of Higher Education and Scientific Research, Rusafa Street 52, Baghdad, 55509, Iraq
Al-Farabi Kazakh National University, Al-Farabi Avenue 71, Almaty, 050040, Kazakhstan
Department of Mathematical and Physical Sciences, College of Arts and Sciences, University of Nizwa, Nizwa 616, Oman
Department of Mathematical Sciences, College of Science, Princess Nourah bint Abdulrahman University, P.O. Box 84428, Riyadh, 11671, Saudi Arabia
Department of Physics, College of Science, University of Bisha, P.O. Box 344, Bisha, 61922, Saudi Arabia
Astrophysics Research Centre
Center for Theoretical Physics
Department of Physics
Department of Physics
Ministry of Higher Education and Scientific Research
Al-Farabi Kazakh National University
Department of Mathematical and Physical Sciences
Department of Mathematical Sciences
Department of Physics
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