J/MNRAS/440/799 Low Ionization BALQSOs MgII and AlIII variability (Vivek+, 2014)
Variability in Low Ionization Broad Absorption Line outflows.
Vivek M., Srianand R., Petitjean P., Mohan V., Mahabal A., Samui S.
<Mon. Not. R. Astron. Soc., 440, 799-820 (2014)>
=2014MNRAS.440..799V 2014MNRAS.440..799V
ADC_Keywords: QSOs ; Spectroscopy
Keywords: galaxies: active - quasars: absorption lines - quasars: general
Abstract:
We present results of our time variability studies of MgII and AlIII
absorption lines in a sample of 22 Low Ionization Broad Absorption
Line QSOs (LoBAL QSOs) at 0.2≤zem≤2.1 using the 2-m
telescope at IUCAA Girawali Observatory over a time-scale of 10d to
7.69years in the QSO's rest frame. Spectra are analysed in conjunction
with photometric light curves from Catalina Real-Time Transient
Survey. Long time-scale (i.e. ≥1-year) absorption line variability
is seen in eight cases (36 per cent systems) while only four of them
(i.e. 18 per cent systems) show variability over short time-scales
(i.e. <1-year). We notice a tendency of highly variable LoBAL QSOs to
have high ejection velocity, low equivalent width and low redshift.
The detection rate of variability in LoBAL QSOs showing Fe
fine-structure lines (FeLoBAL QSOs) is less than that seen in non-Fe
LoBAL QSOs. Absorption line variability is more frequently detected in
QSOs having continuum dominated by Fe emission lines compared to rest
of the QSOs. Confirming these trends with a bigger sample will give
vital clues for understanding the physical distinction between
different BAL QSO sub-classes. We correlate the absorption line
variability with various parameters derived from continuum light
curves and find no clear correlation between continuum flux and
absorption line variabilities. However, sources with large absorption
line variability also show large variability in their light curves. We
also see appearance/disappearance of absorption components in two
cases and clear indications for profile variations in four cases. The
observed variability can be best explained by a combination of process
driven by continuum variations and clouds transiting across the line
of sight.
Description:
Our LoBAL QSO sample consists of 22 QSOs brighter than i=17.5mag
that are accessible from IUCAA Girawali Observatory (IGO). Five of
these sources show broad FeII absorption in the resonance lines and
in the excited fine-structure lines.
All the new observations presented here were carried out using the 2-m
telescope at IUCAA Girawali Observatory (IGO). The spectra were
obtained using the IUCAA Faint Object Spectrograph (IFOSC). We have
been observing the sample from the year 2006 with the aim of studying
the time variability in the BALs over a range of time-scales.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 110 22 Source parameters measured from the data
table1.dat 83 105 Log of observations
table4.dat 80 131 Equivalent width measurements
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See also:
J/ApJ/698/1095 : The FIRST-2MASS red QSO survey. II. (Urrutia+, 2009)
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 QSO SDSS name (JHHMMSS.ss+DDMMSS.s)
21- 30 A10 --- SName Short name (JHHMM+DDMM)
31- 32 A2 -- n_SName [+* ] Fe emission (1)
34- 38 F5.3 --- zem [0.5/2.0] Emission redshift (2)
40- 44 F5.3 --- zabs [0.5/2.0] Absorption redshift (3)
46- 52 F7.1 km/s Vmax [1865/20747] Maximum velocity (4)
54- 58 F5.2 0.1nm [3/33]?=- Average MgII equivalent width
59 A1 --- n_ [a] a corresponds to average AlIII
equivalent width in
61- 67 E7.2 10-7W Lbol Bolometric luminosity (5)
69- 75 E7.2 Msun Mbh Black hole mass (derived from Lbol assuming
Eddington accretion)
77- 81 F5.2 mag Dm ?=- Median variability Δm value
83- 86 F4.2 mag e_Dm ?=- standard deviation of Dm
88- 93 F6.3 mag/yr Slope ?=- Slope of Δm/Δt graph
95- 99 F5.3 mag/yr e_Slope ? rms uncertainty on Slope
101-110 A10 --- Line Absorption line(s) probed in this study
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Note (1): Note as follows:
+ = FeLoBAL QSO source (showing fine-structure Fe lines)
* = source with strong Fe emission
Note (2): zem is obtained from the fitting of SDSS composite.
Note (3): zabs corresponds to the maximum optical depth.
Note (4): Vmax is calculated for the MgII line from the normalized SDSS spectra.
Vmax is identified as the maximum velocity at which source flux matches with
the continuum.
Note (5): Lbol is computed using the prescription, Lbol=7.9xνFνB, of
Marconi et al. (2004MNRAS.351..169M 2004MNRAS.351..169M).
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 19 A19 --- SDSS QSO SDSS name (JHHMMSS.ss+DDMMSS.s)
21- 30 A10 --- SName Short name
32- 42 A11 --- Inst Observatory/Instrument (2)
45- 54 A10 "date" Date Observation date
56- 60 I5 d MJD Modified Julian date
62- 63 I2 min Exp1 [5/80] Exposure time of 1 exposure
64 A1 --- --- [x]
65 I1 --- Nexp Number of exposures
67- 70 I4 0.1nm lam.min Lower value of wavelength coverage
71 A1 --- --- [-]
72- 76 I5 0.1nm lam.max Upper value of wavelength coverage
78- 80 I3 km/s Res Resolution
82- 83 I2 --- S/N [2/62] Signal-to-noise ratio (1)
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Note (1): values quoted are mean of S/N calculated per pixel over the
wavelength range 5800Å-6200Å.
Note (2): IGO = IUCAA Girawali Observatory
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- --- [SDSS]
6- 15 A10 --- SName Short name
17- 27 A11 --- n_SName Note on component
29- 33 A5 --- Ion Ion
35- 41 A7 --- Epoch Epoch identification (1)
44- 48 I5 d MJD ?=- Modified Julian date
50- 55 F6.1 0.1nm lam.min Lower value of wavelength range
56 A1 --- --- [-]
57- 62 F6.1 0.1nm lam.max Upper value of wavelength range
64- 67 F4.1 0.1nm Wrest Rest-frame equivalent width
69- 71 F3.1 0.1nm e_Wrest rms uncertainty on Wrest
73- 80 A8 --- Comment "Variable"
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Note (1): 7 and 1 in the parenthesis refer to IFOSC 7 and IFORS 1 data,
respectively.
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 21-Jan-2015