NASA/IPAC EXTRAGALACTIC DATABASE
Date and Time of the Query: 2019-08-24 T00:52:55 PDT
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For refcode 2007ApJS..168....1K:
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Copyright by American Astronomical Society. Reproduced by permission
2007ApJS..168....1K Virial Masses of Black Holes from Single Epoch Spectra of Active Galactic Nuclei Brandon C. Kelly and Jill Bechtold ABSTRACT We describe the general problem of estimating black hole masses of active galactic nuclei (AGNs) by calculating the conditional probability distribution of MBH 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 MBH given the observed luminosity, line width, and redshift. We show how to combine the broad-line 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 MBH. Simulation was used to assess how the distribution of MBH inferred 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 M_BH_ and to indirectly probe the C IV region size-luminosity (R-L) relationship. A linear regression of log L{lambda} (1549 Angstrom) on log M_BH_ found that L_1549_{propto} M^1.17+-0.22^_BH_. A linear regression also found that M_BH_{propto} L^0.41+-0.07^_1549_ FWHM^2^_CIV, implying a C IV R-L relationship of the form R _CIV_{propto} L^0.41+-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 MBH over simply using the continuum luminosity, statistically justifying its use. We estimated M_BH_ from both C IV and H{beta} 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 {propto} L^1/2^_UV_ for both lines. Subject headings: galaxies: active-line: profiles-methods: data analysis-methods: statistical-quasars: emission lines
Retrieve 118 NED objects in this reference.
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