Retrolensing by a charged black hole

TL;DR

This paper analytically calculates the deflection angle for retrolensing by charged black holes in Reissner-Nordstrom spacetime, exploring observable light curves and image separations near the light sphere.

Contribution

It provides an exact analytical expression for the deflection angle in strong deflection limit without approximations in electric charge.

Findings

Derived the deflection angle analytically in strong deflection limit.

Analyzed retrolensing light curves and double image separation.

Applicable to charged black holes near the solar system.

Abstract

Compact objects with a light sphere such as black holes and wormholes can reflect light rays like a mirror. This gravitational lensing phenomenon is called retrolensing and it is an interesting tool to survey dark and compact objects with a light sphere near the solar system. In this paper, we calculate the deflection angle analytically in the strong deflection limit in the Reissner-Nordstrom spacetime without Taylor expanding it in the power of the electric charge. Using the obtained deflection angle in the strong deflection limit, we investigate the retrolensing light curves and the separation of double images by the light sphere of Reissner-Nordstrom black holes.