Relativistic images in Randall-Sundrum II braneworld lensing

Abstract

In this paper, we explore the properties of gravitational lensing by black holes in the Randall-Sundrum II braneworld. We use numerical techniques to calculate lensing observables using the tidal Reissner-Nordstrom (TRN) and Garriga-Tanaka metrics to examine supermassive black holes and primordial black holes. We introduce a new way to parametrize tidal charge in the TRN metric which results in a large increase in image magnifications for braneworld primordial black holes compared to their 4-dimensional analogs. Finally, we offer a mathematical analysis that allows us to assess the validity of the logarithmic approximation of the bending angle for any static, spherically symmetric metric. We apply this to the TRN metric and show that it is valid for any amount of tidal charge.