Accretion Disk for regular black holes with sub-Planckian curvature

TL;DR

This paper studies the optical features of accretion disks around regular black holes with sub-Planckian curvature and Minkowskian cores, highlighting observable differences from other black hole types.

Contribution

It derives null geodesics and analyzes light ray features for a new class of regular black holes, proposing observational distinctions based on optical signatures.

Findings

Brightness mainly from direct emission

Limited contribution from lensed and photon rings

Distinct optical features compared to Bardeen black holes

Abstract

We investigate the accretion disk for a sort of regular black holes which are characterized by sub-Planckian curvature and Minkowskian core. We derive null geodesics outside the horizon of such regular black holes and analyze the feature of the light rays from the accretion disk which can be classified into direct emission, lensed rings, and photon rings. We find that the observed brightness under different emission models is mainly determined by direct emission, while the contribution from the flux of the lensed and photon rings is limited. By comparing with Bardeen black hole with a dS core, it is found that the black hole with a Minkowskian core exhibits distinct astronomical optical features when surrounded by accretion disk, which potentially provides a way to distinguish these two sorts of black holes by astronomical observation.