Abstract: The spatially-unresolved sub-parsec region of quasars (rapidly accreting supermassive black holes) is a dynamic environment where the most important processes related to BH accretion and feedback are taking place. Studying this region observationally, however, requires somewhat different approaches that are not hurdled by the spatial resolution requirement. A hallmark characteristic of quasars is their ubiquitous variability over a wide range of wavelengths and timescales from intra-day to decades, which provides unique and critical constraints on the structure, dynamics, and radiative processes in the innermost emitting regions of accreting SMBHs that are otherwise difficult to probe. I will give a brief overview on variability studies to understand the inner structures of quasars, with an example of measuring the sizes of the dust torus and the gaseous broad-line region using light echos. Finally I will discuss the prospects of advancing quasar variability science in the upcoming time-domain era of LSST.
Bio: 2002 BS in physics from Tsinghua Univ.; 2009 PhD in Astrophysics from Princeton; Clay Fellow at Harvard-Smithsonian Center for Astrophysics (2009-2012) and Hubble Fellow at Carnegie Observatories (2012-2015) before joining the faculty at UIUC in 2015. Currently I am a tenured associate professor in Astronomy at UIUC.