Weak field limit of Reissner-Nordstrom black hole lensing

TL;DR

This paper analyzes gravitational lensing effects caused by a charged Reissner-Nordstrom black hole in the weak field limit, deriving analytical formulas for image positions and magnifications.

Contribution

It provides new analytical expressions for lensing observables considering the black hole's charge, highlighting how charge affects image separation.

Findings

Image separation increases with charge

Total magnification remains unchanged by charge

Analytical formulas for deflection and time delay are derived

Abstract

We study gravitational lensing by a Reissner-Nordstrom (RN) black hole in the weak field limit. We obtain the basic equations for the deflection angle and time delay and find analytical expressions for the positions and amplifications of the primary and secondary images. Due to a net positive charge, the separation between images increases, but no change in the total magnification occurs.