J/ApJ/669/791 Quasar black hole masses (Wilhite+, 2007)
The effect of variability on the estimation of quasar black hole masses.
Wilhite B.C., Brunner R.J., Schneider D.P., Vanden Berk D.E.
<Astrophys. J., 669, 791-800 (2007)>
=2007ApJ...669..791W 2007ApJ...669..791W
ADC_Keywords: Active gal. nuclei ; QSOs ; Spectroscopy ; Ultraviolet
Keywords: galaxies: active - quasars: general - techniques: spectroscopic
Abstract:
We investigate the time-dependent variations of ultraviolet (UV) black
hole mass estimates of quasars in the Sloan Digital Sky Survey (SDSS).
From SDSS spectra of 615 high-redshift (1.69<z<4.75) quasars with
spectra from two epochs, we estimate black hole masses using a
single-epoch technique, which employs an additional, automated
night-sky line removal and relies on UV continuum luminosity and CIV
λ1549 emission-line dispersion. Mass estimates show variations
between epochs at about the 30% level for the sample as a whole. We
determine that for our full sample, measurement error in the line
dispersion likely plays a larger role than the inherent variability in
terms of contributing to variations in mass estimates between epochs.
However, we use the variations in quasars with r-band spectral
signal-to-noise ratio greater than 15 to estimate that the
contribution to these variations from inherent variability is roughly
20%. We conclude that these differences in black hole mass estimates
between epochs indicate that variability does not make a large
contribution to the current factor of 2 scatter between mass estimates
derived from low- and high-ionization emission lines.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 68 615 Variable quasar sample
table2.dat 62 615 The 1450Å luminosity, CIV line dispersion,
and estimated black hole mass at both epochs
for all objects
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See also:
J/ApJ/613/682 : AGN central masses & broad-line region sizes (Peterson+, 2004)
http://www.sdss.org : SDSS Home Page
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- [WBS2007] Running quasar identification number
5- 22 A18 --- SDSS The SDSS identification (HHMMSS.ss+DDMMSS.s)
24- 28 I5 d MJDh Modified Julian Date of high-S/N ratio epoch
30- 34 I5 d MJDl Modified Julian Date of low-S/N ratio epoch
36- 40 F5.3 --- zh Redshift of high-S/N ratio epoch
42- 46 F5.3 --- e_zh Uncertainty in z-HSN
48- 52 F5.3 --- zl Redshift of low-S/N ratio epoch
54- 58 F5.3 --- e_zl Uncertainty in z-LSN
60- 63 F4.1 --- S/Nh Signal-to-Noise of high-S/N ratio epoch
65- 68 F4.1 --- S/Nl Signal-to-Noise of low-S/N ratio epoch
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- [WBS2007] Running quasar identification number
5- 8 I4 10+37W Lh High-S/N ratio epoch 1450Å luminosity (1)
10- 12 I3 10+37W e_Lh Uncertainty in Lh (1)
14- 17 I4 10+37W Ll Low-S/N ratio epoch 1450Å luminosity (1)
19- 21 I3 10+37W e_Ll Uncertainty in Ll (1)
23- 26 I4 km/s sig.h High-S/N ratio epoch CIV 1550Å
line dispersion
28- 31 I4 km/s e_sig.h Uncertainty in sig.h
33- 37 I5 km/s sig.l Low-S/N ratio epoch CIV 1550Å
line dispersion
39- 42 I4 km/s e_sig.l Uncertainty in sig.l
44- 47 F4.2 [solMass] MBHh High-S/N ratio epoch log of Black hole mass
49- 52 F4.2 [solMass] e_MBHh Uncertainty in MBHh
54- 57 F4.2 [solMass] MBHl Low-S/N ratio epoch log of Black hole mass
59- 62 F4.2 [solMass] e_MBHl Uncertainty in MBHl
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Note (1): In units of 10+44erg/s.
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History:
From electronic version of the journal
References:
Wandel et al., Paper I 1999ApJ...526..579W 1999ApJ...526..579W
Peterson et al., Paper II 2004ApJ...613..682P 2004ApJ...613..682P, Cat. J/ApJ/613/682
(End) Greg Schwarz [AAS], Patricia Vannier [CDS] 27-Jan-2010