Semiclassical gravitational effects on the gravitational lensing in the
spacetime of topological defects

Kimet Jusufi, Farook Rahaman, Ayan Banerjee

Published:

We utilize a recent formulation to compute the deflection angle of a light
ray, namely, the Gauss-Bonnet theorem (GBT) to explore the semiclassical
gravitational effects in the spacetime of a point-like global monopole and a
cosmic string. Previously the Gauss-Bonnet theorem [Class. Quant. Grav. 25,
235009 (2008)] was proposed as an alternative way of compute the deflection
angle of light. In the present article we have used the celebrated GBT that
applied to the optical metric as well as the geodesic method in computing the
deflection angle. For an important observation, when we modify the domain of
integration we found an exact result between GBT and the standard approach up
to the third-order contributions terms for the cosmic string and global
monopole deflection angles, receptively.