New insights on the quasars central region from microlensed quasars

Our detailed understanding of the working engine of quasars is still incomplete. Several basic questions remain such as: How is the supermassive black hole in the center of quasars fed ? What is the geometry and kinematics of the gas flow near the black hole ? The slow advances in answering these questions during the last decades advocates for new research methods. The analysis of the microlensing-induced deformations of multiply-imaged quasars is one such technique. It starts to be used as a tool to measure the temperature profile of the accretion disk, to estimate the size and study the geometry of the region emitting the broad emission lines. However, up to now, these applications have concerned mostly a handful of systems. In this talk, I will discuss the occurence of microlensing in a sample known strongly-lensed quasars and present the variety of emission-line deformations which is observed. I will also explain how spectroscopic follow-up of strongly-lensed quasars in the survey era should provide important insights on the quasar structure