Polarized image of an equatorial emitting ring around a Konoplya-Zhidenko rotating non-Kerr black hole

TL;DR

This paper studies how the polarization images of light around a rotating non-Kerr black hole are affected by a deformation parameter, providing potential observational tests for deviations from standard black hole models.

Contribution

It introduces the impact of a deformation parameter on polarized images around a non-Kerr black hole, extending the analysis beyond Kerr black holes.

Findings

Polarization intensity decreases monotonically with deformation parameter for equatorial magnetic fields.

Polarization varies non-monotonically with deformation parameter for perpendicular magnetic fields.

Deformation parameter influences the shape of Stokes Q-U loops, aiding in black hole spacetime testing.

Abstract

We investigate the polarized images of an equatorial emitting ring around a Konoplya-Zhidenko rotating non-Kerr black hole, which introduces an additional deformation parameter. The deformation parameter $\eta$ allows the spin parameter to extend beyond the bounds imposed by the standard Kerr black hole. The results indicate that the polarized images depend not only on the magnetic field configuration, fluid velocity, and observer inclination angle, but also on the deformation parameter and the spin parameter. As the deformation parameter increases, the polarization intensity decreases monotonically when the magnetic field lies in the equatorial plane, whereas it does not vary monotonically when the magnetic field is perpendicular to the equatorial plane. The variation of the electric vector position angle with the deformation parameter is complex. For a fixed deformation parameter, the polarization intensity exhibits a non-monotonic dependence on the spin parameter and varies with azimuthal angle. We also investigate the impact of the deformation parameter on the Stokes Q-U loops. The imprint of the deformation parameter in polarized images may serve as a high-precision observational probe for detecting deviations of black hole spacetime from the Kerr geometry and testing general relativity.