https://doi.org/10.1140/epjc/s10052-026-15683-3
Regular Article - Theoretical Physics
Polarized radiative transfer of Kerr–Newman black hole
1
College of Physics and Optoelectronic Engineering, Chongqing Normal University, 401331, Chongqing, People’s Republic of China
2
Guangxi Key Laboratory for Relativistic Astrophysics, School of Physical Science and Technology, Guangxi University, 530004, Nanning, People’s Republic of China
3
School of Big Data and Artificial Intelligence, Fuyang University of Technology, 236000, Fuyang, People’s Republic of China
4
Universidade Federal de Campina Grande, 58429-900, Campina Grande, PB, Brazil
5
School of Physics and Astronomy, China West Normal University, 637000, Nanchong, People’s Republic of China
a
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Received:
21
February
2026
Accepted:
9
April
2026
Published online:
4
May
2026
Abstract
In this analysis, we investigate the polarization radiation imaging of Kerr–Newman black holes, with a particular focus on the impact of black hole charge on photon propagation and polarization characteristics. By extending the traditional Walker–Penrose method, which is limited by its reliance on specific symmetric structures and Killing tensors, we overcome these limitations by constructing an ordinary differential equations (ODEs) numerical framework that combines the photon orbit equation with the polarization parallel transport equation. This allows for the self-consistent evolution of photon trajectories and polarization states in any spacetime backgrounds without relying on specific symmetries. Using this framework, we analyze the effects of black hole spin and charge on the polarization characteristics of radiation from both prograde and retrograde accretion disks. Our results show that black hole charge can significantly modify photon trajectories and polarization patterns: increasing charge compresses and distorts the EVPA structure on photon-ring scales, inducing localized rotations and asymmetries that may provide a potential diagnostic of a nonzero black hole charge.
© The Author(s) 2026
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