Accretion Disks, Jets and Blazar Variability

Abstract

Although blazar variability is probably dominated by emission from relativistic jets, accretion disks should be present in all blazars. These disks produce emission over most of the electromagnetic spectrum; various unstable processes operate in those disks which lead to variable emission. Here I summarize some of the most relevant disk mechanisms for AGN variability. I also discuss some aspects of jet variability, focusing on the possibility that ultrarelativisitic jets of modest opening angle can reconcile TeV blazar emission with the many subluminal VLBI knots seen in those sources. Finally, I present recently illuminated characteristics of optical microvariability of different classes of AGN which have important implications for the dominant processes involved.