J/ApJ/814/150 Variability of SDSS broad absorption line QSOs (Wang+, 2015)
Evidence for photoionization-driven broad absorption line variability.
Wang T., Yang C., Wang H., Ferland G.
<Astrophys. J., 814, 150 (2015)>
=2015ApJ...814..150W 2015ApJ...814..150W (SIMBAD/NED BibCode)
ADC_Keywords: QSOs ; Spectroscopy
Keywords: line: formation; quasars: absorption lines; quasars: emission lines
Abstract:
We present a qualitative analysis of the variability of quasar broad
absorption lines using the large multi-epoch spectroscopic data set of
the Sloan Digital Sky Survey Data Release 10. We confirm that
variations of absorption lines are highly coordinated among different
components of the same ion or the same absorption component of
different ions for CIV, SiIV, and NV. Furthermore, we show that the
equivalent widths (EWs) of the lines decrease or increase
statistically when the continuum brightens or dims. This is further
supported by the synchronized variations of emission and
absorption-line EWs when the well-established intrinsic Baldwin effect
for emission lines is taken into account. We find that the emergence
of an absorption component is usually accompanied by the dimming of
the continuum while the disappearance of an absorption-line component
is accompanied by the brightening of the continuum. This suggests that
the emergence or disappearance of a CIV absorption component is only
the extreme case, when the ionic column density is very sensitive to
continuum variations or the continuum variability the amplitude is
larger. These results support the idea that absorption-line
variability is driven mainly by changes in the gas ionization in
response to continuum variations, that the line-absorbing gas is
highly ionized, and in some extreme cases, too highly ionized to be
detected in UV absorption lines. Due to uncertainties in the
spectroscopic flux calibration, we cannot quantify the fraction of
quasars with asynchronized continuum and absorption-line variations.
Description:
We searched the SDSS DR10 archive for quasars that were observed two
or more times. We merged the quasar catalog of SDSS data release 7
(DR7; Schneider et al. 2010, VII/260) with that of DR10 (Paris et al.
2014, VII/270). Duplicated entries are removed. We compared this
catalog with the SDSS spectroscopic catalog and selected quasars with
multi-spectroscopic observations.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 69 1084 Variable absorption line components
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See also:
VII/270 : SDSS quasar catalog: tenth data release (Paris+, 2014)
VII/260 : The SDSS-DR7 quasar catalog (Schneider+, 2010)
II/294 : The SDSS Photometric Catalog, Release 7 (Adelman-McCarthy+, 2009)
J/ApJS/217/11 : HeI* in broad absorption line QSOs (Liu+, 2015)
J/MNRAS/440/799 : Low Ionization BALQSO MgII & AlIII variability (Vivek+, 2014)
J/MNRAS/434/163 : QSOs narrow absorption line variability (Hacker+, 2013)
J/ApJ/777/168 : CIV & SiIV broad absorption line in SDSS (Filiz+, 2013)
J/ApJS/194/45 : QSO properties from SDSS-DR7 (Shen+, 2011)
J/A+A/525/A37 : QSO variability indexes in SDSS Stripe 82 (Meusinger+, 2011)
J/AJ/142/78 : New 2.2<z<3 quasars from SDSS and UKIDSS (Wu+, 2011)
J/ApJ/696/924 : UV and X-Ray radio-quiet QSOs (Gibson+, 2009)
J/ApJ/641/78 : CIV variability in 105 SDSS quasars (Wilhite+, 2006)
J/ApJS/167/334 : Radiative recombination data for plasmas (Badnell+, 2006)
J/ApJS/165/1 : BAL QSOs from SDSS DR3 (Trump+, 2006)
J/ApJ/633/638 : Variable quasar sample from SDSS (Wilhite+, 2005)
J/ApJ/613/129 : Equivalent widths of QSOs (Wise+, 2004)
J/ApJ/475/469 : Composite HST Spectrum of Quasars (Zheng+ 1997)
http://www.sdss3.org/ : SDSS-III home page
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 19 A19 --- SDSS SDSS identifier (JHHMMSS.ss+DDMMSS.s)
20 A1 --- f_SDSS [*] Flag on SDSS (1)
22- 25 I4 --- Plate SDSS plate number
27- 31 I5 d MJD [51578/56104] Modified Julian Date of
SDSS exposure
33- 36 I4 --- Fiber SDSS Fiber identifier
38- 43 I6 km/s Vel1 [-45900/-2400]? Lower range of velocity
45 A1 --- --- [~]
47- 52 I6 km/s Vel2 [-42700/0]? Upper range of velocity
54 A1 --- Ref r = Plate-MJD-Fiber reference spectrum
56- 57 I2 --- CIV ? The C IV variability sign (2)
59- 60 I2 --- SiIV ? The Si IV variability sign (2)
62- 63 I2 --- NV ? The N V variability sign (2)
65- 66 I2 --- Cont ? The continuum variability sign (2)
68- 69 I2 --- Em ? The emission line variability sign (2)
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Note (1):
* = An object with appearance or disappearance of one or more absorption
line components with respect to the reference spectrum.
Note (2): Relative to the reference spectrum. Code as follows:
1 = either equivalent width of an absorption line or emission line
strengthens or continuum brightens in comparison with the reference
spectrum,
-1 = an absorption or emission line weakens or continuum dims,
0 = insignificant variation,
Blank for no available data.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 03-Mar-2016