J/ApJS/242/28 MgII-BAL quasar variability in SDSS spectra (Yi+, 2019)
Variability of low-ionization broad absorption-line quasars based on multi-epoch
spectra from the Sloan Digital Sky Survey.
Yi W., Brandt W.N., Hall P.B., Vivek M., Grier C.J., Ak N.F.,
Schneider D.P., McGraw S.M.
<Astrophys. J. Suppl. Ser., 242, 28 (2019)>
=2019ApJS..242...28Y 2019ApJS..242...28Y
ADC_Keywords: QSOs; Spectra, optical; Redshifts; Equivalent widths
Keywords: galaxies: active ; quasars: absorption lines ; quasars: general
Abstract:
We present absorption variability results for 134 bona fide MgII broad
absorption-line (BAL) quasars at 0.46≤z≤2.3 covering days to ∼10yr
in the rest frame. We use multiple-epoch spectra from the Sloan
Digital Sky Survey, which has delivered the largest such BAL
variability sample ever studied. MgII-BAL identifications and related
measurements are compiled and presented in a catalog. We find a
remarkable time-dependent asymmetry in the equivalent width (EW)
variation from the sample, such that weakening troughs outnumber
strengthening troughs, the first report of such a phenomenon in BAL
variability. Our investigations of the sample further reveal that (i)
the frequency of BAL variability is significantly lower (typically by
a factor of 2) than that in high-ionization BALQSO samples, (ii)
MgII-BAL absorbers tend to have relatively high optical depths and
small covering factors along our line of sight, (iii) there is no
significant EW-variability correlation between MgII troughs at
different velocities in the same quasar, and (iv) the EW-variability
correlation between MgII and AlIII BALs is significantly stronger than
that between MgII and CIV BALs at the same velocities. These
observational results can be explained by a combined
transverse-motion/ionization-change scenario, where transverse motions
likely dominate the strengthening BALs while ionization changes and/or
other mechanisms dominate the weakening BALs.
Description:
We use spectroscopic data from the Sloan Digital Sky Survey-I/II
(hereafter SDSS) and the Baryon Oscillation Spectroscopic Survey of
SDSS-III (hereafter BOSS). SDSS and BOSS are wide-field, large sky
survey projects using the dedicated 2.5m telescope at the Apache Point
Observatory, New Mexico.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 42 134 Properties of MgII-BAL QSOs in the sample
table3.dat 107 484 MgII-BAL trough identifications and
quantitative measurements
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See also:
VII/260 : The SDSS-DR7 quasar catalog (Schneider+, 2010)
VII/279 : SDSS quasar catalog: twelfth data release (Paris+, 2017)
J/AJ/106/848 : QSO MgII absorption line systems (Drinkwater+, 1993)
J/ApJS/165/1 : BAL QSOs from SDSS DR3 (Trump+, 2006)
J/ApJ/692/758 : BAL QSOs in SDSS-DR5 (Gibson+, 2009)
J/MNRAS/405/2302 : Improved redshifts for SDSS quasar spectra (Hewett+, 2010)
J/ApJS/194/45 : QSO properties from SDSS-DR7 (Shen+, 2011)
J/ApJ/748/131 : MgII absorbers in SDSS-DR7 quasar catalog (Shen+, 2012)
J/ApJ/777/168 : CIV and SiIV BAL troughs in SDSS (Filiz+, 2013)
J/ApJ/779/161 : MgII absorbers in 0.4<z<2.3 SDSS QSOs (Seyffert+, 2013)
J/ApJ/791/88 : C IV BAL troughs properties in quasars (Filiz+, 2014)
J/MNRAS/440/799 : Low Ionization BALQSOs MgII & AlIII var. (Vivek+, 2014)
J/ApJ/814/150 : Variability of SDSS broad absorption line QSOs (Wang+, 2015)
J/ApJ/824/130 : SDSS/BOSS/TDSS CIV BAL quasars (Grier+, 2016)
J/ApJ/831/7 : SDSS-RM project: peak velocities of QSOs (Shen+, 2016)
J/MNRAS/463/2640 : SDSS-DR12 QSOs MgII absorption systems (Raghunathan+, 2016)
J/ApJS/235/11 : Absorption features in SDSS. I. MgII doublets (Chen+, 2018)
J/A+A/616/A114 : CIV BAL disappearance in SDSS QSOs (De Cicco+, 2018)
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)
21- 25 F5.3 --- z [0.4/2.3] Spectroscopic redshift
27- 28 I2 --- Ne [2/47] Number of epochs
30- 35 F6.2 --- RL [1/897]?=-1 Radio loudness
from Shen+, 2011, J/ApJS/194/45
37- 42 F6.2 mag iMag [-28.4/-22.9] Absolute i band magnitude
from Schneider+ 2010, VII/260
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 19 A19 --- SDSS SDSS identifier (JHHMMSS.ss+DDMMSS.s)
21- 29 F9.5 deg RAdeg [15.9/360] Right Ascension (J2000)
31- 39 F9.5 deg DEdeg [-11/65.1] Declination (J2000)
41- 45 I5 d MJD1 [51614/57460] First Modified Julian Date
47- 51 I5 d MJD2 [51936/58230] Second Modified Julian Date
53- 57 F5.2 --- chi2 [0.4/60.4] Model χ2
59 I1 --- Nv [0/9] Number of variable regions
in the trough pair
61- 66 I6 km/s Vmax [-25956/-1390] Maximum limits of trough velocity
68- 73 I6 km/s Vmin [-24111/1269] Minimum limits of trough velocity
75- 79 F5.2 --- d1 [-0.2/0.9] BAL depth at MJD1
81- 85 F5.2 --- d2 [-0.05/0.9] BAL depth at MJD2
87- 91 F5.1 0.1nm EW1 [0.5/110.4] First equivalent width; in Angstroms
93- 96 F4.2 0.1nm e_EW1 [0.04/4.3] Uncertainty in EW1
98-102 F5.1 0.1nm EW2 [0.1/112.3] Second equivalent width; in Angstroms
104-107 F4.2 0.1nm e_EW2 [0.03/4.3] Uncertainty in EW2
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 03-Dec-2019