J/ApJS/250/3 Variable MgII NALs in SDSS DR14 (Chen+, 2020)
The variable MgII narrow absorption line systems.
Chen Z.-F., Qin H.-C., Gui R.-J., Yi S.-X., Chen Z.-G., Gao Y.-C.,
Pang T.-T., Mo X.-H.
<Astrophys. J. Suppl. Ser., 250, 3 (2020)>
=2020ApJS..250....3C 2020ApJS..250....3C
ADC_Keywords: QSOs; Spectra, optical; Redshifts; Equivalent widths
Keywords: Astronomy data analysis ; Active galaxies ; Quasars ; Galaxies ;
Quasar absorption line spectroscopy
Abstract:
Compared to high ionization CIV absorption lines, variable MgII
absorption lines are rare. Using spectra from the Sloan Digital Sky
Survey, we investigate the variations in MgII narrow absorption lines
(NALs) for quasars with multi-epoch observations. We have compiled
8958 MgII NALs in the spectral regions from the red wings of CIV
emission lines to the red wings of MgII emission lines. Among these
8958 MgII NALs, 22 variable NALs are detected with
|ΔWrλ2796|≥3σW and with velocity offsets
ranging from υr=522 to 145513km/s. We find that: (1) the
detected frequency of MgII NALs with υr≤10000km/s is
significantly larger than the uniformly random value expected for the
MgII NALs with υr>10000km/s, (2) the incidence rates of the
variable MgII NALs with υr≤10000km/s are much larger than
those with υr>10000km/s, (3) the velocity offsets of
variable MgII NALs with υr≤10000km/s are much smaller than
the maximum velocities expected from radiation-driven outflows, and
(4) the variations of variable MgII NALs with υr≤10000km/s
are obviously correlated with the changes in the quasar radiative
output. Therefore, the 16 variable MgII NALs, whose velocities are
smaller than the maximum velocities expected from radiation-driven
outflows, are likely related to quasar outflows, while the 6 variable
MgII NALs, whose velocities are much larger than the maximum
velocities expected from radiation-driven outflows, possibly
originated in intervening gas. We also find that both the variations
and fractional variations in absorption strengths are not related to
the velocity offsets of MgII NALs and the time intervals between the
two epochs of observations. Also, the fractional variations in
absorption strengths are inversely correlated with absorption
strengths. In addition, both the associated and intervening MgII NALs
can significantly vary on a timescale of days.
Description:
In this work, we make use of the quasars with multi-epoch observations
of the SDSS to investigate the variations of MgII NALs. We take the
visual inspection redshifts from the DR14Q catalog (Paris+ 2018, VII/286)
as the quasar redshifts, which have been confirmed to be robust
(Chen+ 2019ApJS..244...36C 2019ApJS..244...36C).
After screenings described in Section 2.1, we compile 34406 quasars,
whose spectra can be downloaded from http://data.sdss.org/sas/dr14/
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 110 22746 Catalog of Mg II absorption line systems
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See also:
VII/269 : SDSS Quasar Catalog, DR9Q (Paris+, 2012)
V/147 : The SDSS Photometric Catalogue, Release 12 (Alam+, 2015)
VII/286 : SDSS quasar catalog, fourteenth data release (Paris+, 2018)
J/AJ/106/848 : QSO MgII absorption line systems (Drinkwater+, 1993)
J/A+AS/108/287 : Atomic data (Verner+, 1994)
J/MNRAS/354/L25 : MgII absorbers in SDSS QSOs (Bouche+, 2004)
J/ApJ/613/129 : Equivalent widths of QSOs (Wise+, 2004)
J/ApJ/633/638 : Variable quasar sample from SDSS (Wilhite+, 2005)
J/ApJ/665/990 : SDSS DR2 BAL QSOs (Ganguly+, 2007)
J/ApJS/171/1 : Census of QSOs Narrow Absorption Lines (Misawa+, 2007)
J/ApJ/679/239 : Associated MgII absorbers (Vanden+, 2008)
J/ApJ/714/1521 : Spectroscopy of galaxies around distant QSOs (Chen+, 2010)
J/AJ/141/137 : Pittsburgh SDSS Mg II QSO catalog (Quider+, 2011)
J/A+A/546/A67 : Catalog of strong MgII absorbers (Lawther+, 2012)
J/A+A/548/A66 : SDSS Quasar Catalog, DR9Q (Paris+, 2012)
J/ApJ/748/131 : MgII absorbers in SDSS-DR7 quasar catalog (Shen+, 2012)
J/ApJ/777/168 : CIV & SiIV BAL troughs in SDSS (Filiz+, 2013)
J/ApJ/779/161 : MgII absorbers in 0.4<z<2.3 SDSS QSOs (Seyffert+, 2013)
J/MNRAS/434/163 : QSOs narrow absorption line variability (Hacker+, 2013)
J/MNRAS/450/3904 : Quasars narrow absorption lines from SDSS (Chen+, 2015)
J/ApJ/814/150 : Variability of SDSS broad absorption line QSOs (Wang+, 2015)
J/ApJS/221/32 : Narrow MgII absorption lines from SDSS-DR9Q (Chen+, 2015)
J/ApJS/235/11 : Absorption features in SDSS. I. MgII doublets (Chen+, 2018)
J/ApJS/236/39 : CIV narrow absorption line syst. in SDSS-DR14 (Chen+, 2018)
J/ApJS/239/23 : CIV NAL systems from SDSS-DR14 quasar spectra (Chen+, 2018)
J/ApJ/862/22 : CIV BAL SDSS QSO obs. with Gemini (Rogerson+, 2018)
J/ApJS/242/28 : MgII-BAL quasar variability in SDSS spectra (Yi+, 2019)
J/ApJS/243/2 : SiIV & NV absorption line SDSS quasar systems (Chen+, 2019)
http://data.sdss.org/sas/dr14/ : SDSS DR14 data
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 5 I5 --- Seq [1/11373] Identification number
of NAL pair
7- 24 A18 --- SDSSo Quasar SDSS DR14Q identifier
(position based names as in VII/286,
sometimes incorrect)
26- 30 I5 --- Plate [266/10000] SDSS plate number
32- 36 I5 d MJD [51613/57520] SDSS Modified Julian Date
of the observation
38- 41 I4 --- Fiber [1/1000] SDSS fiber identifier
43- 48 F6.4 --- zem [0.54/2.34] Redshift from emission lines
50- 55 F6.4 --- zabs [0.33/2.33] Redshift of MgII NAL
57- 60 F4.2 0.1nm EW2796 [0.07/8.7] Rest frame MgII 2796Å
equivalent width; in Angstrom units
62- 66 F5.2 0.1nm e_EW2796 [0.02/13.6] Uncertainty in EW2796
68- 71 F4.2 0.1nm EW2803 [0.03/7.4] Rest frame MgII 2803Å
equivalent width; in Angstrom units
73- 77 F5.2 0.1nm e_EW2803 [0.02/17] Uncertainty in EW2803
79- 85 F7.3 10-17cW/m2/nm F3000 [0.2/241.4]?=0 Continuum flux
at rest frame 3000Å (1)
87- 91 F5.3 10-17cW/m2/nm e_F3000 [0.09/5.4]?=0 Uncertainty in F3000 (1)
93- 98 I6 km/s Vr [-5947/151956] Offset velocity of
MgII NAL relative to quasar redshift
100-103 I4 --- ID [1/8958] Identification number
of Mg II NAL
105-106 I2 --- f_EW2796 [-2/1]? Flag on EW2796 (2)
108-110 F3.1 --- SL [0/9.9]? Significance level of
the variation (3)
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Note (1): In unit of 10-17erg/s/cm2/Å, which are measured
from the pseudo-continuum.
Note (2): Flag as follows:
0 = stable Mg II NAL (11350 occurrences);
-1 = weakened Mg II NAL (10 occurrences);
1 = enhanced Mg II NAL (12 occurrences);
-2 = disappeared Mg II NAL (1 occurrence);
2 = emerged Mg II NAL (no occurrence or 11373 blanks???).
Note (3): Significance level of the variation, which is the ratio
of |ΔWrλ2796|/σW.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 27-Oct-2020