For refcode 2007ApJS..168....1K: Retrieve 118 NED objects in this reference. Please click here for ADS abstract
NED Abstract
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 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 MBH. Simulation was
used to assess how the distribution of MBH 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{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 RL
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: activeline: profilesmethods: data
analysismethods: statisticalquasars: emission lines
Retrieve 118 NED objects in this reference. Please click here for ADS abstract
