Probing the broad emission line region of quasars using gravitational microlensing

This thesis exploits microlensing of the BLR to constrain its geometry and kinematics. BLR microlensing is investigated through two complementary methods: (i) a model-independent decomposition of the microlensed part of the quasar spectrum, and (ii) comparison of observations to simulated line profile distortions. Those two approaches are applied to high-quality spectra of the lensed quasars HE0435-1223 and QSO2237+0305. Both quadruply-imaged quasars show significant line profile distortions that can be robustly attributed to microlensing. This investigation especially focuses on the image D of quasar HE0435-1223 and on the image A of QSO2237+0305, which are affected by the largest microlensing effects.