Long-Term Profile Variability of Double-Peaked Emmission Lines in AGNs
  An increasing number of AGNs exhibit broad, double-peaked Balmer emission lines, which arise from the outer regions of the accretion disk which fuels the AGN. The line profiles vary on timescales of 5--10 years. Our group has monitored a set of 20 double-peaked emitters for the past 8 years (longer for some objects). Here we describe a project to characterize the variability patterns of the double-peaked H alpha line profiles and compare with those of two simple models: a circular disk with a spiral arm and an elliptical disk. 
Karen T. Lewis, Michael Eracleous (Penn State), Jules P. Halpern   (Columbia), and Thaisa Storchi-Bergmann (IF-UFRGS)