Charged-particle motion around a rotating non-Kerr black hole immersed in a uniform magnetic field

We present analytical solutions of Maxwell's equations around a rotating non-Kerr black hole immersed in an external uniform magnetic field. The influence of a magnetic field on the effective potential of the radial motion of a charged test particle around a rotating non-Kerr black hole immersed in an external magnetic field are investigated by using the Hamilton-Jacobi equation of motion. The dependence of the minimal radius of the circular orbits r(mc) and the radius of the innermost stable circular orbits (ISCOs) from the deformation and the magnetic parameters for the motion of charged particles around a rotating non-Kerr black hole are also presented. An increase of the magnetic field decreases the ISCO radius, while the negative deformation parameter may lead to a larger ISCO radius. A comparison of the numerical results of ISCOs around a non-Kerr black hole with the observational data for the ISCO radius of rapidly rotating black holes [R. Shafee et al., Astrophys. J. 636, L113 (2006)] provides the upper limit for the deformation parameter as epsilon <= 22. DOI: 10.1103/PhysRevD.87.064042