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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
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:

       FileName      Lrecl  Records   Explanations

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


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

   Bytes Format Units   Label     Explanations

   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


Byte-by-byte Description of file: table2.dat

   Bytes Format Units      Label     Explanations

   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

Note (1): In units of 10+44erg/s.



History:
    From electronic version of the journal

References:
    Wandel et al.,     Paper I     1999ApJ...526..579W
    Peterson et al.,   Paper II    2004ApJ...613..682P, Cat. J/ApJ/613/682
(End)                  Greg Schwarz [AAS], Patricia Vannier [CDS]    27-Jan-2010