Study of quasar variability

The Palomar-QUEST Variability Survey has been completed. This thesis has analyzed the data set with the goal of determining the variability of a large sample of quasars.;We construct light curves for each individual quasar. We interpret the light curves in terms of a structure function analysis. A slope is extracted from the scaling of the structure function to measure the power law of the quasar optical variability, taking the power spectral density to behave as a power law of the frequency of variation, f-alpha. Monte carlo simulations are used to estimate the errors on the model and the final data quality. With these estimates, individual quasars are assigned a chi2 value and nearly every event has a reduced chi 2 less than 10. The first 100 light curves and structure functions with errors are shown in the Appendix.;We have shown that the final distribution of power law coefficients alpha of 1944 quasars is inconsistent with a model with a simple value of alpha. Several models with different alpha are required to explain the behavior of the sample.;We find that quasars are less variable on all time scales for increasing luminosity. We also find that the quasars with black hole masses below 10 8 show a lower power law then the average. This means less massive quasars are less variable at long time scales.