J/ApJ/862/22 CIV broad abs. line SDSS QSO obs. with Gemini (Rogerson+, 2018)
Emergence and variability of broad absorption line quasar outflows.
Rogerson J.A., Hall P.B., Ahmed N.S., Hidalgo P.R., Brandt W.N., Ak N.F.
<Astrophys. J., 862, 22 (2018)>
=2018ApJ...862...22R 2018ApJ...862...22R
ADC_Keywords: QSOs; Spectra, optical; Redshifts
Keywords: galaxies: active ; quasars: absorption lines
Abstract:
We isolate a set of quasars that exhibit emergent CIV broad absorption
lines (BALs) in their spectra by comparing spectra in the Sloan
Digital Sky Survey (SDSS) Data Release 7 and the SDSS/BOSS Data
Releases 9 and 10. After visually defining a set of emergent BALs,
follow-up observations were obtained with the Gemini Observatory for
105 quasars. We find an emergence rate consistent with the previously
reported disappearance rate of BAL quasars given the relative numbers
of non-BAL and BAL quasars in the SDSS. We find that candidate newly
emerged BALs are preferentially drawn from among BALs with smaller
balnicity indices, shallower depths, larger velocities, and smaller
widths. Within two rest-frame years (average) after a BAL has emerged,
we find it equally likely to continue increasing in equivalent width
in an observation 6 months later (average) as it is to start
decreasing. From the time separations between our observations, we
conclude that the coherence timescale of BALs is less than 100
rest-frame days. We observe coordinated variability among pairs of
troughs in the same quasar, likely due to clouds at different
velocities responding to the same changes in ionizing flux, and the
coordination is stronger if the velocity separation between the two
troughs is smaller. We speculate that the latter effect may be due to
clouds having on average lower densities at higher velocities owing to
mass conservation in an accelerating flow, causing the absorbing gas
in those clouds to respond on different timescales to the same
ionizing flux variations.
Description:
The SDSS used a dedicated 2.5m f/5 Ritchey-Chretien altitude-azimuth
telescope located at Apache Point Observatory in New Mexico, USA. The
telescope was outfitted with a photometric camera and a multi-object,
fiber-fed spectrograph with a wavelength coverage of 3800-9200Å and
a resolving power from 1500 to 3000.
We leveraged the multi-epoch nature of the DR7, DR9, and DR10 catalogs
to search for a set of quasars that had been spectroscopically
observed at least twice over all three data releases.
We obtained data on 105 targets from the candidate emergence sample
using the twin Gemini telescopes. We used the Gemini Multi-object
Spectrograph (GMOS) (one on each telescope), outfitted with a 1.0"
wide long slit to observe individually each target in our sample.
Our Gemini follow-up of the 105 targets was spread over three
observing semesters: 2013A, 2013B, and 2014A.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 104 105 *List of the observations made for each of
the 105 quasars in this work
table4.dat 60 105 The rest-frame time between successive
observations of a given quasar
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Note on table3.dat: the spectra are only available on demand to the author.
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See also:
II/183 : UBVRI Photometric Standards (Landolt 1992)
II/294 : The SDSS Photometric Catalog, Release 7 (Adelman-McCarthy+, 2009)
VII/260 : The SDSS-DR7 quasar catalog (Schneider+, 2010)
V/139 : The SDSS Photometric Catalog, Release 9 (Adelman-McCarthy+, 2012)
VII/270 : SDSS quasar catalog: tenth data release (Paris+, 2014)
VII/279 : SDSS quasar catalog: twelfth data release (Paris+, 2017)
J/ApJ/641/78 : CIV variability in 105 SDSS quasars (Wilhite+, 2006)
J/ApJS/165/1 : BAL QSOs from SDSS DR3 (Trump+, 2006)
J/MNRAS/410/860 : Redshift dependence of BAL QSOs (Allen+, 2011)
J/A+A/548/A66 : SDSS Quasar Catalog, DR9Q (Paris+, 2012)
J/ApJ/763/37 : Metals in SDSS QSOs. I. 1.5<z<4.5 CIV abs. (Cooksey+, 2013)
J/ApJ/777/168 : CIV and SiIV broad abs. line troughs in SDSS (Filiz+, 2013)
J/ApJ/788/123 : IRTF J-band spectrum of Mrk 231 (Leighly+, 2014)
J/MNRAS/454/3962 : 188 CIV BAL QSOs from SDSS DR7 (He+, 2015)
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/ApJS/236/39 : CIV narrow abs. line systems in SDSS-DR14 (Chen+, 2018)
J/ApJS/239/23 : CIV NAL systems from SDSS-DR14 quasar spectra (Chen+, 2018)
J/A+A/616/A114 : CIV BAL disappearance in SDSS QSOs (De Cicco+, 2018)
http://www.sdss3.org/ : SDSS-III home page
Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 18 A18 --- SDSS SDSS DR7 designation (HHMMSS.ss+DDMMSS.s; J2000)
20- 23 F4.2 --- zspec [1.7/4.2] Spectroscopic redshift
25- 32 F8.2 d SDSS1 ? Modified Julian Date, SDSS Observation 1
34- 41 F8.2 d SDSS2 ? Modified Julian Date, SDSS Observation 2
43- 50 F8.2 d BOSS1 ? Modified Julian Date, BOSS Observation 1
52- 59 F8.2 d BOSS2 ? Modified Julian Date, BOSS Observation 2
61- 68 F8.2 d GEM1 ? Modified Julian Date, Gemini Observation 1
70- 77 F8.2 d GEM2 ? Modified Julian Date, Gemini Observation 2
79- 86 F8.2 d GEM3 ? Modified Julian Date, Gemini Observation 3
88- 95 F8.2 d GEM4 ? Modified Julian Date, Gemini Observation 4
97-104 F8.2 d GEM5 ? Modified Julian Date, Gemini Observation 5
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 18 A18 --- SDSS SDSS DR7 object designation
20- 26 F7.2 d delta12 [2.8/1208]? Rest-frame days
between 1st and 2nd observation
28- 34 F7.2 d delta23 [1.9/1080]? Rest-frame days
between 2nd and 3rd observation
36- 41 F6.2 d delta34 [18.7/353]? Rest-frame days
between 3rd and 4th observation
43- 48 F6.2 d delta45 [6/306.6]? Rest-frame days
between 4th and 5th observation
50- 54 F5.2 d delta56 [4/37.4]? Rest-frame days
between 5th and 6th observation
56- 60 F5.2 d delta67 [5.8/10.4]? Rest-frame days
between 6th and 7th observation
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 17-Jul-2019