Modelling the Gravitationally Lensed Quasar PKS 1830-211

Abstract

The two lines of sight towards the gravitationally lensed quasar PKS 1830-211 have been used as a probe for a number of cosmological parameters like the temperature of the cosmic microwave background, variations in the fundamental constants, and the Hubble constant. Apart from being used as a cosmological probe, this gravitational lens system also offers a unique opportunity to study both the interstellar medium of lens galaxy and the radio jet of the background quasar. Although numerous high resolution observations have been performed towards the source quasar, there is no one single lens model that can account for all the observed characteristics of this system. As a first step towards achieving a unified model for both the background source and the lens galaxy, in this thesis, we have built a refined lens model using high resolution observations performed over the last decade. Using the new lens model, we estimate a value for the Hubble constant (H0 = 76+/-28 km=s=Mpc). Though the uncertainty of H0 is large, we found that it scales linearly with the uncertainty on the lens position and better constraints on the lens position through future observation could improve our H0 estimate. We have also discussed several new methods – both observational and theoretical – with which the refined lens model can be greatly improved.