Abstract
We describe the general problem of estimating black hole masses of active galactic nuclei (AGNs) by calculating the conditional probability distribution of M_{BH} given some set of observables. Special attention is given to the case where one uses the AGN continuum luminosity and emission line widths to estimate M_{BH}, and we outline how to set up the conditional probability distribution of M_{BH} given the observed luminosity, line width, and redshift. We show how to combine the broadline estimates of M _{BH} with information from an intrinsic correlation between M _{BH} and L, and from the intrinsic distribution of M_{BH}, in a manner that improves the estimates of M_{BH}. Simulation was used to assess how the distribution of M_{BH} inferred from the broadline mass estimates differs from the intrinsic distribution, and we find that this can lead to an inferred distribution that is too broad. We use these results and a sample of 25 sources that have recent reverberation mapping estimates of AGN black hole masses to investigate the effectiveness of using the C IV emission line to estimate M_{BH} and to indirectly probe the C IV region sizeluminosity (RL) relationship. A linear regression of log L _{λ} (1549 Å) on log M_{BH} found that L _{1549} ∝ M_{BH}^{1.17±0.22}. A linear regression also found that M_{BH} ∝ L_{1549} ^{0.41±0.07}FWHM_{C IV}^{2}, implying a C IV RL relationship of the form R_{C IV} ∝ L_{1549} ^{0.41±0.07}. Including the C IV line FWHM resulted in a reduction of a factor of ∼ 1/3 in the error in the estimates of M _{BH} over simply using the continuum luminosity, statistically justifying its use. We estimated M_{BH} from both C IV and Hβ for a sample of 100 sources, including new spectra of 29 quasars. We find that the two emission lines give consistent estimates if one assumes R ∝ L _{UV}^{1/2} for both lines.
Original language  English (US) 

Pages (fromto)  118 
Number of pages  18 
Journal  Astrophysical Journal, Supplement Series 
Volume  168 
Issue number  1 
DOIs  
State  Published  Jan 2007 
Externally published  Yes 
Keywords
 Galaxies: active
 Line: profiles
 Methods: data analysis
 Methods: statistical
 Quasars: emission lines
ASJC Scopus subject areas
 Astronomy and Astrophysics
 Space and Planetary Science
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Black hole mass estimates
Kelly, B. C. (Creator) & Bechtold, J. (Creator), Centre de Donnees Strasbourg (CDS), 2009
DOI: 10.26093/cds/vizier.21680001, https://cdsarc.cds.unistra.fr/vizbin/cat/J/ApJS/168/1
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