Characterization of H-beta and [OIII] for Determining Black Hole Masses of Quasars

Type Conference Paper
Names Mallory Molina, M. J. Wolf, E. J. Hooper, A. I. Sheinis, P. H. Sell
Proceedings Title Bulletin of the American Astronomical Society
Conference Name American Astronomical Society, AAS Meeting #219, #243.12
Volume 219
Date January 1, 2012
URL http://adsabs.harvard.edu/abs/2012AAS...21924312M
Library Catalog NASA ADS
Abstract We analyze the spectra of nearby, luminous quasars to calculate the black hole masses based on an empirical method by Vestergaard and Peterson (2006, ApJ, 641, 689), as well as to look at the forbidden [OIII] line for its credibility as a surrogate for estimating the stellar velocity dispersion of the host galaxy. Our initial measurements of the widths of the narrow [OIII] line in the quasar spectra preliminarily show no strong correlation to the measured stellar velocity dispersions of the host galaxies. For the black hole estimates we specifically concentrate on the H-beta spectral line. We use a multiple Gaussian fitting routine to isolate the broad lines from the narrow lines around H-beta. We measure the full width half maximum (FWHM) of the broad line and use that to solve for the black hole mass. While fitting the multiple Gaussians, we noted in some objects a shelf on the red side of H beta. This feature, which we suspect to be due to iron, complicates determination of the H-beta FWHM. To resolve this issue we are working with Brad Peterson from the Ohio State University to apply an iron template from Kovacevic, Popovic, and Dimitrijevic (2010, ApJS, 189, 15) that will be used to subtract this iron shelf from the H beta line. If we are able to sufficiently remove the shelf, we can then get a more accurate measure of the line width, and thus calculate more accurate black hole masses. This work was supported by the National Science Foundation's REU program through NSF Award AST-1004881.
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