Shadows and optical appearance of black bounces illuminated by a thin accretion disk

TL;DR

This paper investigates the shadows and optical appearances of a family of black bounce geometries, which interpolate between black holes and wormholes, revealing broader photon regions compared to Schwarzschild black holes.

Contribution

It introduces a detailed ray-tracing analysis of black bounce spacetimes and their optical signatures under thin accretion disk illumination.

Findings

Broader photon ring regions in black bounce solutions.

Distinct shadow features compared to Schwarzschild black holes.

Optical appearances depend on accretion disk models.

Abstract

We study the light rings and shadows of an uniparametric family of spherically symmetric geometries interpolating between the Schwarzschild solution, a regular black hole, and a traversable wormhole, and dubbed as black bounces, all of them sharing the same critical impact parameter. We consider the ray-tracing method in order to study the impact parameter regions corresponding to the direct, lensed, and photon ring emission, finding a broadening of all these regions for black bounce solutions as compared to the Schwarzschild one. Using this, we determine the optical appearance of black bounces when illuminated by three standard toy models of optically and geometrically thin accretion disks viewed in face-on orientation.