Previous | Session 27 | Next
S. Gezari, J. P. Halpern (Columbia.University), M. Eracleous (Penn-State University), A. V. Filippenko (UC Berkeley)
We present the results of 15 years of spectroscopic monitoring of broad, double-peaked H\alpha and H\beta lines in a sample of 10 broad-line radio galaxies. Double-peaked emitters are a new class of AGN that exhibit extremely broad, double-peaked line profiles that are well modeled by emission from photoionized gas in a relativistic Keplerian accretion disk around a central black hole. A ubiquitous property of double-peaked broad emission lines is variability of the profile shape on the timescale of months to years. This slow, systematic variability of the line profile is on the same timescale as dynamical changes in an accretion disk, and is unrelated to the shorter timescale variability (~ days) seen in the overall flux in the line due to reverberation of the variable ionizing continuum. Variability in the profile shape provides important constraints on models for the dynamics of the line-emitting gas in the disk. We use the long-term profile variability to definitively rule out alternative ``non-accretion disk'' scenarios for the source of the broad double-peaked line emission, test models for dynamical processes in the accretion disk, and measure physical parameters of the accretion disk and its central black hole.
Previous | Session 27 | Next
Bulletin of the American Astronomical Society, 36 5
© 2004. The American Astronomical Society.