On-axis absorption and scattering of charged massive scalar waves by Kerr-Newman black-bounce spacetime

Abstract: We investigate the absorption and scattering of charged massive scalar waves by Kerr-Newman black-bounce spacetime when the waves are incident along the rotation axis. We calculate the geometrical and glory scattering cross sections using the classical analytical method and the corresponding absorption and scattering cross sections using the partial wave method, and show that they are in excellent agreement. Our findings indicate that a faster (slower) rotating spacetime or a more repulsive (attractive) electric force tends to reduce (increase) the absorption cross section and result in larger (smaller) angular widths of the scattered wave oscillations. Additionally, the rotation parameter exerts a suppressive influence on superradiance, which contrasts with the enhancing effect of the repulsive electric force. The regularization parameter $k$ is found to modify the absorption or scattering cross sections only weakly, but can cause a noticeable reduction of the superradiance. For the effect of field mass, it is found that a heavier scalar field leads to a larger absorption cross section and a wider interference fringe of the differential scattering cross section. When superradiance happens, i.e., the absorption cross section becomes negative, it is also found that the differential scattering cross section only changes smoothly, with no apparent qualitative feature showing up.