Gravitational Lensing by Black Holes in General Relativity and R2 Gravity

Abstract

The phenomenon of gravitational lensing in both strong and weak deflection limits is discussed in this thesis. Solutions of Buchdahl’s ODE in R2 gravity are considered as spacetimes in this work. Weak deflection angle by the ap plication of Gauss Bonnet theorem for asymptotically flat special Buchdahl inspired metric was found and the magnification and image distortions are observed modeling M87* black hole as a lens. Also, analytic expression for strong deflection angle is determined followed by modeling black holes Sgr A* and M87* as lens. On the basis of which image positions and separa tions are investigated. For the stationary axi-symmetric SBI solution in R2 gravity, weak deflection angle is computed. Magnifications for primary and secondary images are explored by considering M87* as a lens.