Circular orbits and observational signatures in regular black hole spacetimes

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 [Formula: see text] and a spacetime deformation factor [Formula: see text]. 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 [Formula: see text], 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.