NOAO >   Observing Info >   Approved Programs >   2003B-0030

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Proposal Information for 2003B-0030


PI: Karen T. Lewis, Pennsylvania State University, lewis@astro.psu.edu
Address: Astronomy Department, 525 Davey Lab, University Park, PA 16803, USA

CoI: Michael Eracleous, Pennsylvania State University
CoI: Steinn Sigurdsson, Pennsylvania State University

Title: Black Hole Masses in Double-Peaked Emission-Line AGNs

Abstract: Over the past decade, our group has been actively monitoring a subset of radio-loud AGNs which exhibit double-peaked emission lines. These lines, thought to originate in the outer regions of the accretion disk, provide an excellent means for studying the dynamics of the disk. The line profiles are observed to vary on timescales from a few years to decades and their variations are un-related to the more rapid fluctuations of the ionizing continuum. However, the physical timescales associated with the accretion disk - the thermal, dynamical, and sound-crossing times - depend sensitively on the mass of the black hole (M_\bullet). Within the range of possible black hole masses, it is difficult to distinguish these physical timescales, and thus the physical processes which are the source of these variations. Thus we propose to determine the masses of the black holes in these double- peaked emitters, by exploiting the correlation between M_\bullet and \sigma, the stellar velocity dispersion measured on length scales comparable to the effective radius of the galaxy. These observations will complement our ongoing program to determine M_\bullet in the northern targets from our sample using the \it Hobby-Eberly Telescope. Equipped with this crucial piece of information we will be able to make rapid progress towards understanding the physical mechanisms which are driving the variability in these double-peaked emission-line AGNs.


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