QED effect on a black hole shadow

Taking QED effect into account, we investigate the shadows of a static black hole with magnetic monopoles and neutral black holes in magnetic fields through the numerical backward ray-tracing method. For a static black holes with a magnetic monopole, we obtain the relation between the shadow radius and the coupling constant. For neutral black holes in uniform magnetic fields, we find that the shadow curves deviate very little from the ellipses for an equatorial observer, and we read the linear relation between the eccentricity and the coupling constant. For theta(o) not equal pi/2, we find that the shadow curves can be well approximated by ellipses in most cases, except when the magnetic field is very strong and the observer sits around the angle theta(o) = pi/4 or 3 pi/4. Moreover, we extend our investigation to a neutral static black hole surrounded by a current loop.

Automated summary

In this study, the shadows of static black holes with magnetic monopoles and neutral black holes in magnetic fields were investigated using numerical backward ray-tracing method. The relation between shadow radius and coupling constant for black holes with magnetic monopoles, and the linear relation between eccentricity and coupling constant for neutral black holes in uniform magnetic fields were obtained. It was found that shadow curves can be well approximated by ellipses in most cases, except under certain conditions of strong magnetic fields and observer positions. The study was extended to include a neutral static black hole surrounded by a current loop.