SIGNATURE WORK
CONFERENCE & EXHIBITION 2022

Gravitational lensing comprises phenomena whereby light emitted by a distant astronomical object is bent due to the gravitational field of a massive foreground object, such as a star or a galaxy. Aside from the mass which we can observe, dark matter also has a gravitational field that distorts light. Since the nature of dark matter is an important question in cosmology, it is an interesting problem to build a gravitational lensing model that considers both luminous matter and dark matter. In this thesis, basic lensing concepts such as deflection angle, magnification factor, and caustics are introduced, and the lensing properties of the Schwarzschild lens are discussed. Then these are generalized for arbitrary smooth mass distributions. After that, the lensing properties of the Singular Isothermal Sphere (SIS) and Plummer’s model are derived using these formulae. Finally, a novel 2-component model is constructed by using Plummer’s model for the luminous mass distribution of a galaxy and a SIS to model the dark matter halo surrounding it. It is shown that the model can have at most three images and, based on the range of parameters, we explore three different cases. The relative contributions of SIS and Plummer’s model toward the overall deflection angle are also evaluated.