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2007ApJS..168....1K - Astrophys. J., Suppl. Ser., 168, 1-18 (2007/January-0)

Virial masses of black holes from single epoch spectra of active galactic nuclei.


Abstract (from CDS):

We describe the general problem of estimating black hole masses of active galactic nuclei (AGNs) by calculating the conditional probability distribution of MBHgiven some set of observables. Special attention is given to the case where one uses the AGN continuum luminosity and emission line widths to estimate MBH, and we outline how to set up the conditional probability distribution of MBHgiven the observed luminosity, line width, and redshift. We show how to combine the broad-line estimates of MBHwith information from an intrinsic correlation between MBHand L, and from the intrinsic distribution of MBH, in a manner that improves the estimates of MBH. Simulation was used to assess how the distribution of MBHinferred from the broad-line 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 MBHand to indirectly probe the C IV region size-luminosity (R-L) relationship. A linear regression of logLλ(1549 Å) on logMBHfound that L1549∝M1.17±0.22BH. A linear regression also found that MBH∝L0.41±0.071549FWHM2_CIV_, implying a C IV R-L relationship of the form R_CIV∝L0.41±0.07^1549. Including the C IV line FWHM resulted in a reduction of a factor of ∼1/3 in the error in the estimates of MBHover simply using the continuum luminosity, statistically justifying its use. We estimated MBHfrom 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∝L1/2UV for both lines.

Abstract Copyright:

Journal keyword(s): Galaxies: Active - Line: Profiles - Methods: Data Analysis - Methods: Statistical - Galaxies: Quasars: Emission Lines

VizieR on-line data: <Available at CDS (J/ApJS/168/1): table5.dat>

Nomenclature: Table 5: [KB2007] JHHMMSS.s+DDMMSS.s N=100.

Simbad objects: 125

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