Polarization distribution in the image of a synchrotron emitting ring around a regular black hole

TL;DR

This study analyzes the polarization images of synchrotron emitting rings around regular Hayward and Bardeen black holes, revealing how magnetic charge influences polarization features and aiding understanding of regular black holes and nonlinear electrodynamics.

Contribution

It provides a comparative analysis of polarization images in Hayward and Bardeen black holes, highlighting the effects of magnetic charge on polarization characteristics and their relation to Schwarzschild black holes.

Findings

Polarization features are similar in Hayward and Bardeen black holes.

Increasing magnetic charge enhances polarization intensity and electric vector angle.

Polarization in Hayward black holes is closer to Schwarzschild case.

Abstract

The polarized images of a synchrotron emitting ring are studied in the regular Hayward and Bardeen black hole spacetimes. These regular black holes carry a magnetic field in terms of gravity coupled to nonlinear electrodynamics. Results show that the main features of the polarization images of the emitting rings are similar in these two regular black hole spacetimes. As the magnetic charge parameter increase, the polarization intensity and the electric vector position angle in the image plane increase in Hayward and Bardeen black hole spacetimes. Moreover, the polarization intensity and electric vector position angle in the image of the emitting ring in the Hayward black hole spacetime are closer to those in the Schwarzschild case. The effects of the magnetic charge parameter on the Strokes $Q-U$ loops are also slightly smaller in the Hayward black hole spacetime. This information stored in the polarization images around Hayward and Bardeen black holes could help understand regular black holes and the gravity coupled to nonlinear electrodynamics.