TY - JOUR
T1 - The sloan digital sky survey reverberation mapping project
T2 - Estimating masses of black holes in Quasars with single-epoch spectroscopy
AU - Bontà, Elena Dalla
AU - Peterson, Bradley M.
AU - Bentz, Misty C.
AU - Brandt, W. N.
AU - Ciroi, S.
AU - De Rosa, Gisella
AU - Alvarez, Gloria Fonseca
AU - Grier, Catherine J.
AU - Hall, P. B.
AU - Santisteban, Juan V.Hernández
AU - Ho, Luis C.
AU - Homayouni, Y.
AU - Horne, Keith
AU - Kochanek, C. S.
AU - Li, Jennifer I.Hsiu
AU - Morelli, L.
AU - Pizzella, A.
AU - Pogge, R. W.
AU - Schneider, D. P.
AU - Shen, Yue
AU - Trump, J. R.
AU - Vestergaard, Marianne
N1 - Funding Information:
The authors are grateful to the referee for suggestions that improved the presentation. E.D.B. is supported by Padua University through grants DOR1715817/17, DOR1885254/ 18, and DOR1935272/19 and by MIUR grant PRIN 2017 20173ML3WW-001. E.D.B. and B.M.P. are grateful for the hospitality of STScI early in this investigation. J.V.H.S. and K.H. acknowledge support from STFC grant ST/R000824/1. Y.S. acknowledges support from an Alfred P. Sloan Research Fellowship and NSF grant AST-1715579. C.J.G., W.N.B., J.R.T., and D.P.S. acknowledge support from NSF grants AST-1517113 and AST-1516784. K.H. acknowledges support from STFC grant ST/R000824/1. P.B.H. acknowledges support from NSERC grant 2017-05983. Y.H. acknowledges support from NASA through STScI grant HST-GO-15650. S.W., L.J., and L.C.H. acknowledge support from the National Science Foundation of China (11721303, 11890693, 11991052) and the National Key R&D Program of China (2016YFA0400702, 2016YFA0400703). M.V. gratefully acknowledges support from the Independent Research Fund Denmark via grant No. DFF 8021-00130.
Publisher Copyright:
© 2020 The Author(s).
PY - 2020/11/10
Y1 - 2020/11/10
N2 - It is well known that reverberation mapping of active galactic nuclei (AGNs) reveals a relationship between AGN luminosity and the size of the broad-line region, and that use of this relationship, combined with the Doppler width of the broad emission line, enables an estimate of the mass of the black hole at the center of the active nucleus based on a single spectrum. An unresolved key issue is the choice of parameter used to characterize the line width, either FWHM or line dispersion σline (the square root of the second moment of the line profile). We argue here that use of FWHM introduces a bias, stretching the mass scale such that high masses are overestimated and low masses are underestimated. Here we investigate estimation of black hole masses in AGNs based on individual or "single-epoch"observations, with a particular emphasis in comparing mass estimates based on line dispersion and FWHM. We confirm the recent findings that, in addition to luminosity and line width, a third parameter is required to obtain accurate masses, and that parameter seems to be Eddington ratio. We present simplified empirical formulae for estimating black hole masses from the Hβ λ4861 and C IV λ1549 emission lines. While the AGN continuum luminosity at 5100 A is usually used to predict the Hβ reverberation lag, we show that the luminosity of the Hβ broad component can be used instead without any loss of precision, thus eliminating the difficulty of accurately accounting for the host-galaxy contribution to the observed luminosity.
AB - It is well known that reverberation mapping of active galactic nuclei (AGNs) reveals a relationship between AGN luminosity and the size of the broad-line region, and that use of this relationship, combined with the Doppler width of the broad emission line, enables an estimate of the mass of the black hole at the center of the active nucleus based on a single spectrum. An unresolved key issue is the choice of parameter used to characterize the line width, either FWHM or line dispersion σline (the square root of the second moment of the line profile). We argue here that use of FWHM introduces a bias, stretching the mass scale such that high masses are overestimated and low masses are underestimated. Here we investigate estimation of black hole masses in AGNs based on individual or "single-epoch"observations, with a particular emphasis in comparing mass estimates based on line dispersion and FWHM. We confirm the recent findings that, in addition to luminosity and line width, a third parameter is required to obtain accurate masses, and that parameter seems to be Eddington ratio. We present simplified empirical formulae for estimating black hole masses from the Hβ λ4861 and C IV λ1549 emission lines. While the AGN continuum luminosity at 5100 A is usually used to predict the Hβ reverberation lag, we show that the luminosity of the Hβ broad component can be used instead without any loss of precision, thus eliminating the difficulty of accurately accounting for the host-galaxy contribution to the observed luminosity.
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U2 - 10.3847/1538-4357/abbc1c
DO - 10.3847/1538-4357/abbc1c
M3 - Article
AN - SCOPUS:85095509541
SN - 0004-637X
VL - 903
JO - Astrophysical Journal
JF - Astrophysical Journal
IS - 2
M1 - 112
ER -