QED and accretion flow models effect on optical appearance of Euler-Heisenberg black holes

TL;DR

This paper studies how quantum electrodynamics effects and different accretion flows influence the optical appearance and shadow of Euler-Heisenberg black holes, revealing that shadow size depends on spacetime geometry while luminosity depends on accretion flow type.

Contribution

It provides a detailed analysis of the optical appearance of Euler-Heisenberg black holes considering QED effects and various accretion models, highlighting the dominance of direct emission in the observed flux.

Findings

Magnetic charge reduces shadow radius.

Shadow size remains unaffected by EH parameter variations.

Direct emission dominates the optical appearance.

Abstract

Taking the quantum electrodynamics (QED) effect into account, we investigate the geometrical-optics appearance of the Euler-Heisenberg (EH) black hole (BH) under the different accretion flows context, which depends on the BH space-time structure and different sources of light. The more significant magnetic charge leads to the smaller shadow radius for the EH BH, while the different values of the EH parameter do not ruin it. Different features of the corresponding two-dimensional shadow images are derived for the three optically thin accretion flow models. It is shown that the total observed intensity in the static spherical accretion flow scenario leads than that of the infalling spherical accretion flow under same parameters, but the size and position of the EH BH shadows do not change in both of these accretions flows, implying that the BH shadow size depends on the geometric space-time and the shadows luminosities rely on the accretion flow morphology. Of particular interest is that a thin disk accretion model illuminated the BH, we found that the contribution of the lensing ring to the total observed flux is less than 5\%, and the photon ring is less than 2\%, indicating that the direct emission dominates the optical appearance of the EH BH. It is also believed that the optical appearance of the BH image depends on the accretion disk radiation position in this scenario, which can serve as a probe for the disk structure around the active galactic nucleus (AGN) of M87^{*} like.