Models and ideas for the interpretation of the variability of double-peaked emission lines

We describe the effort undertaken by our group to interpret the observed variations of the double-peaked emission lines found in a small fraction of AGNs. We describe the application of perturbed disk models to long time series of spectra and their successes and shortcomings. We also summarize our calculations of the observational appearance of the debris released by the tidal disruption of a star by a black hole in an attempt to explain the abrupt appearance of double-peaked lines in AGNs that did not previously have them. We close with a summary of observed variations that cannot be readily explained with the above models and briefly mention additional ideas that appear promising and warrant further exploration..