Geodesics and Shadows in the Kerr-Bertotti-Robinson Black Hole Spacetime
Abstract
In this work, we investigate geodesics and black hole shadows in the Kerr-Bertotti-Robinson spacetime. We show that the equations of motion for null geodesics are separable and admit analytical treatment, whereas timelike geodesics are generally non-separable. Approximate analytical expressions for the photon sphere and the innermost stable circular orbit are derived via perturbative expansions in the magnetic field strength. We further explore the black hole shadow using both numerical and analytical methods, examining the effects of the magnetic field, the observer's inclination angle and radial position. Deviations from the standard Kerr shadow are quantified, and a physical interpretation is provided by introducing asymptotic regimes defined relative to the magnetic field strength.
Cite
@article{arxiv.2507.22494,
title = {Geodesics and Shadows in the Kerr-Bertotti-Robinson Black Hole Spacetime},
author = {Xinyu Wang and Yehui Hou and Xi Wan and Minyong Guo and Bin Chen},
journal= {arXiv preprint arXiv:2507.22494},
year = {2026}
}
Comments
21 pages, 3 figures