ABSTRACT:
Current and future time-domain surveys will provide new insights into the physics of many astronomical objects, providing complementary and orthogonal information to spectroscopy. For quasars, variability provides a probe of the structure and physics of the accretion disk onto the supermassive black hole. In particular, the scaling of variability properties with black hole mass constrains accretion flow solutions, and provides insight into the similarities and differences between supermassive and stellar-mass black holes. In addition,variability provides an important criteria for selecting samples of quasars, facilitating studies of quasar demographics and the quasar-host galaxy connection. Unfortunately, time series of quasar flux measurements (i.e., the quasar lightcurve) often suffer from a number of problems, including irregular and sparse sampling as well as additional variability due to measurement noise. These issues significantly complicate the analysis and quantification of quasar variability. In this talk I will discuss statistical methods that I have recently developed for modeling quasar variability in the time domain which provide reliable and powerful ways of quantifying quasar variability. In addition, I will present recent results obtained from applying my methods to optical and X-ray lightcurves of quasars,including scaling relationships between quasar variability properties and black hole mass.