Influence of Accretion Flow and Magnetic Charge on the Observed Shadows and Rings of the Hayward Black Hole

TL;DR

This study investigates how accretion flows and magnetic charge influence the observable shadows and rings of Hayward black holes, revealing dependencies of shadow size and luminosity on these factors through ray-tracing simulations.

Contribution

It provides a detailed analysis of the effects of magnetic charge and accretion flow models on black hole shadow features, highlighting the role of space-time geometry and accretion properties.

Findings

Shadow radii decrease with increasing magnetic charge.

Luminosity of shadows and rings depends on accretion flow type and magnetic charge.

Photon ring emission has a weak effect on observed luminosity in thin disk accretion.

Abstract

The feature of the observed shadows and rings of an astrophysical black hole (BH) may depend on its accretion flows and magnetic charge. We find that the shadow radii and critical impact parameters of the Hayward BH are decreased with the increase of the magnetic charge. Comparing the Schwarzschild BH with the Hayward BH using the ray-tracing method, we show that the density and deflection of lights increase with the magnetic charge, and the BH singularity does not affect the generation of the shadow. Based on three optically thin accretion flow models, the two-dimensional shadows in celestial coordinates are derived. It is found that the shadow and photon ring luminosities of a Hayward BH surrounded by infalling spherical accretion flow are dimmer than that of a static spherical accretion flow. Taking three kinds of inner radii at which the accretion flow stops radiating, we find that the observed luminosity of a Hayward BH surrounded by a thin disk accretion flow is dominated by the direct emission, and the photon ring emission has a weak influence on it. These results suggest that the size of the observed shadow is related to the space-time geometry, and the luminosities of both the shadows and rings are affected by the accretion flow property and the BH magnetic charge.