Determination of the Central Mass in Active Galactic Nuclei Using Cross‐Correlation Lags and Velocity Dispersions
Open Access
- 10 April 2000
- journal article
- research article
- Published by American Astronomical Society in The Astrophysical Journal
- Vol. 533 (1) , 172-175
- https://doi.org/10.1086/308671
Abstract
We here estimate the mass M of the central object in five active galactic nuclei (AGNs), using the most recent reverberation data obtained by the AGN Watch Consortium. The cross-correlation function (CCF) centroids of the broad Lyα λ1216 and C IV λ1549 lines are used to estimate the size of the broad-line region (BLR) in these sources. We calculate the velocity dispersions of these lines in the root mean square (rms) spectra and then use our results to estimate M. We argue that our technique of calculating the velocity dispersion should work in the general case of an arbitrary line profile, unlike methods that depend on the measurement of the full-width at half-maximum (FWHM) of the broad line. We also show that our results agree with the FWHM method in the limit of a normal (Gaussian) line profile. The masses calculated here are considerably smaller than those calculated with the previous generation of reverberation data.Keywords
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