Weak gravitational lensing by Kerr-MOG Black Hole and Gauss-Bonnet theorem

TL;DR

This paper investigates how modified gravity (MOG) affects light deflection by Kerr black holes using the Gauss-Bonnet theorem, revealing that MOG increases the deflection angle significantly, which has implications for gravitational lensing observations.

Contribution

It introduces a novel application of the Gauss-Bonnet theorem to analyze weak gravitational lensing by Kerr-MOG black holes, highlighting the impact of MOG parameters on light deflection.

Findings

Deflection angle increases with MOG parameter $\alpha$

MOG effects are significant in gravitational lensing

Method extends optical metric analysis to Kerr-MOG black holes

Abstract

The deflection angle of Kerr-MOG black holes is studied for different values of the parameter in modified gravity (MOG). To this end, we employ the Gauss-Bonnet theorem, which was first studied by Gibbons and Werner and then extended by Ono, Ishihara and Asada, who use a generalized optical metric where the deflection of light for an observer and source at finite distance. By using this method, we study the weak gravitational lensing by Kerr-MOG black hole. Our computations show that with an increase in the MOG parameter ($\alpha$), the deflection angle becomes significantly larger than that of Kerr black hole. The results obtained show that MOG effect could be taken into account in the gravitational lensing experiments.