AAS 205th Meeting, 9-13 January 2005
Session 118 Activity in the Nuclei of Galaxies
Oral, Wednesday, January 12, 2005, 10:00-11:30am, California

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[118.05] Black Hole Masses in Double-Peaked Emission Line AGNs

K. T. Lewis, M. Eracleous (Penn State)

An increasing number of AGNs exhibit broad, double-peaked Balmer emission lines. Recent evidence strongly suggests that these lines originate in the accretion disks that fuel the AGNs. The profiles of these lines vary on timescales of a few years to decades in response to dynamical changes within the disk. As a result, these objectspresent a unique opportunity to study and model dynamical phenomena in AGN accretion disks. During the last decade, a sample of radio-loud double-peaked emitters have been monitored and we are currently modeling the profile variability with various accretion disk models. There are several promising models that account for the variability of the double-peaked emission lines, including accretion disks with precessing spiral arms and precessing elliptical disks. These models yield similar line profiles and profile variability patterns, but the expected variability timescales differ. The physical timescales are set by the black hole masses, which have been measured only very indirectly for these objects. To help us distinguish between the viable models and make more rapid progress towards understanding dynamical phenomena in AGN accretion disks, reliable estimates of the black hole masses are necessary. Furthermore, a secure measurement of the black hole mass yields an estimate of the accretion rate (relative to the Eddington rate) in these objects, and places additional constraints on the nature of the accretion flow in these objects. Thus we have been carrying out a campaign to determine the black hole masses in these AGNs using the well-known correlation between the stellar velocity dispersion and the black hole mass. Here we present black hole mass estimates for the first set of double-peaked emitters, which were observed with the CTIO Blanco 4m telescope and discuss the implications. This work was supported by a NASA GSRP fellowship.

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