J/ApJ/883/163 OI abs. search in Keck and VLT spectra of 199 QSOs (Becker+, 2019)
The evolution of OI over 3.2<z<6.5: reionization of the circumgalactic medium.
Becker G.D., Pettini M., Rafelski M., D'Odorico V., Boera E.,
Christensen L., Cupani G., Ellison S.L., Farina E.P., Fumagalli M.,
Lopez S., Neeleman M., Ryan-Weber E.V., Worseck G.
<Astrophys. J., 883, 163 (2019)>
=2019ApJ...883..163B 2019ApJ...883..163B
ADC_Keywords: Intergalactic medium; QSOs; Equivalent widths; Redshifts;
Spectroscopy
Keywords: Intergalactic medium ; Quasar absorption line spectroscopy ;
Circumgalactic medium ; Reionization ; High-redshift galaxies
Abstract:
We present a survey for metal absorption systems traced by neutral
oxygen over 3.2<z<6.5. Our survey uses Keck/ESI and VLT/X-Shooter
spectra of 199 QSOs with redshifts up to 6.6. In total, we detect
74 OI absorbers, of which 57 are separated from the background QSO by
more than 5000km/s. We use a maximum likelihood approach to fit the
distribution of OIλ1302 equivalent widths in bins of redshift
and from this determine the evolution in number density of absorbers
with W1302>0.05Å, of which there are 49 nonproximate systems in
our sample. We find that the number density does not monotonically
increase with decreasing redshift, as would naively be expected from
the buildup of metal-enriched circumgalactic gas with time. The number
density over 4.9<z<5.7 is a factor of 1.7-4.1 lower (68% confidence)
than that over 5.7<z<6.5, with a lower value at z<5.7 favored with 99%
confidence. This decrease suggests that the fraction of metals in a
low-ionization phase is larger at z∼6 than at lower redshifts.
Absorption from highly ionized metals traced by CIV is also weaker in
higher-redshift OI systems, supporting this picture. The evolution of
OI absorbers implies that metal-enriched circumgalactic gas at z∼6 is
undergoing an ionization transition driven by a strengthening
ultraviolet background. This in turn suggests that the reionization of
the diffuse intergalactic medium may still be ongoing at or only
recently ended by this epoch.
Description:
Our survey includes 199 QSOs with redshifts 3.52≤zem≤6.65 observed
with either the X-Shooter spectrograph on the Very Large Telescope
(VLT) or the Echellette Spectrograph and Imager (ESI) on Keck
(see Table 1).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 50 199 QSO spectra used in this work
table2.dat 199 74 Rest-frame equivalent width measurements for
60 QSOs
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See also:
B/eso : ESO Science Archive Catalog (ESO, 1991-2021)
VII/258 : Quasars and Active Galactic Nuclei (13th Ed.) (Veron+ 2010)
VII/283 : The Million Quasars (Milliquas) catalog (6.3) (Flesch, 2019)
VII/289 : SDSS quasar catalog, sixteenth data release (DR16Q) (Lyke+, 2020)
J/A+A/473/791 : CIV absorption in DLAs and sub-DLAs systems (Fox+, 2007)
J/A+A/508/133 : Damped Lymanα absorbers in z>4 QSOs (Guimaraes+, 2009)
J/ApJ/718/392 : SDSS Lyman limit systems at z∼3.5 (Prochaska+, 2010)
J/ApJ/761/112 : High-redshift MgII abs. QSOs with FIRE (Matejek+, 2012)
J/ApJ/755/89 : Metallicities of damped Lyα systems (Rafelski+, 2012)
J/ApJ/763/37 : Metals in SDSS QSOs. I. 1.5<z<4.5 CIV abs. (Cooksey+, 2013)
J/ApJS/206/4 : SED & bol. corrections for luminous QSOs (Krawczyk+, 2013)
J/MNRAS/435/1198 : z∼6 QSOs CIV doublet absorption systems (D'Odorico+, 2013)
J/MNRAS/462/3285 : XQ-100. X-shooter quasar spectra (Perrotta+, 2016)
J/MNRAS/455/1043 : SDSS DLA and absorber quasar samples (Murphy+, 2016)
J/MNRAS/456/4488 : XQ-100 survey neutral gas (Sanchez-Ramirez+, 2016)
J/ApJS/227/11 : PS1 z>5.6 quasars follow-up (Banados+, 2016)
J/MNRAS/472/1850 : Detecting damped Lyα absorbers (Garnett+, 2017)
J/ApJ/869/123 : Keck Lyman continuum spectroscopic survey (Steidel+, 2018)
J/other/RAA/19.29 : Compilation of known QSOs for Gaia (Liao+, 2019)
J/A+A/624/A145 : Large Quasar Astrometric Catalog 5, LQAC-5 (Souchay+, 2019)
J/A+A/631/A78 : QSOs at z∼6 spectral cubes (Stanley+, 2019)
J/ApJS/249/17 : SDSS QSO DR14 spectral properties (Rakshit+, 2020)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1 I1 --- Set Subsample identifier (column added by CDS) (1)
3- 5 I3 --- Seq [1/199] Running sequence number
7- 22 A16 --- Target QSO identifier
24- 28 F5.3 --- z [3.52/6.65] QSO redshift based on the apparent
start of the Lyα forest
30- 38 A9 --- Inst Instrument used for the OI search
40- 44 F5.1 --- S/N [10.4/237.2] Signal-to-noise ratio per 30km/s
near rest wavelength 1285Å
46- 50 F5.3 0.1nm EWOI [0.019/0.22] OIλ1302 rest-frame
equivalent width in Å at which the OI search
is 50% complete (see Section 3.3)
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Note (1): The full sample is made up of three subsamples as follows:
1 = The low-redshift end (3.52<zem<4.81): 100 QSOs from the XQ-100 survey
(Lopez+ 2016A&A...594A..91L 2016A&A...594A..91L).
2 = 41 QSOs over 5.0<zem<5.7 from X-Shooter program 098.A-0111
(PI: M. Rafelski).
3 = 58 QSOs over 5.62<zem<6.65 drawn from our own programs and the VLT
and Keck archives.
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 6 F6.4 --- z [3.24/6.26] Absorber redshift
8- 10 A3 --- f_z Flag(s) on z (1)
12- 27 A16 --- Target QSO identifier
29- 33 F5.3 0.1nm OI-1302 [0.02/0.9] Rest-frame OIλ1302
equivalent width (2)
35- 39 F5.3 0.1nm e_OI-1302 [0.001/0.04] Uncertainty in OI-1302
41 A1 --- f_OI-1302 Flag on OI-1302 (3)
43 A1 --- l_CII-1334 Limit flag on CII-1334
44- 48 F5.3 0.1nm CII-1334 [0.02/1.2]? Rest-frame CIIλ1334
equivalent width (2)
50- 54 F5.3 0.1nm e_CII-1334 [0.001/0.04]? Uncertainty in CII-1334
56 A1 --- f_CII-1334 Flag on CII-1334 (3)
58 A1 --- l_SiII-1260 Limit flag on SiII-1260
59- 63 F5.3 0.1nm SiII-1260 [0.04/1.1]? Rest-frame SiIIλ1260
equivalent width (2)
65- 69 F5.3 0.1nm e_SiII-1260 [0.001/0.03]? Uncertainty in SiII-1260
71 A1 --- f_SiII-1260 Flag on SiII-1260 (3)
73 A1 --- l_SiII-1304 Limit flag on SiII-1304
74- 78 F5.3 0.1nm SiII-1304 [0.007/0.8] Rest-frame SiIIλ1304
equivalent width (2)
80- 84 F5.3 0.1nm e_SiII-1304 [0.001/0.04]? Uncertainty in SiII-1304
86 A1 --- f_SiII-1304 Flag on SiII-1304 (3)
88 A1 --- l_SiII-1526 Limit flag on SiII-1526
89- 93 F5.3 0.1nm SiII-1526 [0.008/0.9]? Rest-frame Si II 1526
equivalent width (2)
95- 99 F5.3 0.1nm e_SiII-1526 [0.001/0.07]? Uncertainty in SiII-1526
101 A1 --- f_SiII-1526 Flag on SiII-1526 (3)
103-107 F5.3 0.1nm MgII-2796 [0.1/2.5]? Rest-frame MgIIλ2796
equivalent width (2)
109-113 F5.3 0.1nm e_MgII-2796 [0.002/0.09]? Uncertainty in MgII-2796
115-119 A5 --- f_MgII-2796 Flag(s) on MgII-2796 (3)
121 A1 --- l_MgII-2803 Limit flag on MgII-2803
122-126 F5.3 0.1nm MgII-2803 [0.07/2]? Rest-frame MgIIλ2803
equivalent width (2)
128-132 F5.3 0.1nm e_MgII-2803 [0.002/0.15]? Uncertainty in MgII-2803
134 A1 --- f_MgII-2803 Flag on MgII-2803 (3)
136 A1 --- l_SIV-1393 Limit flag on SIV-1393
137-141 F5.3 0.1nm SIV-1393 [0.009/0.7]? Rest-frame SIVλ1393
equivalent width (2)
143-147 F5.3 0.1nm e_SIV-1393 [0.002/0.1]? Uncertainty in SIV-1393
149 A1 --- f_SIV-1393 Flag on SIV-1393 (3)
151 A1 --- l_SiIV-1402 Limit flag on SiIV-1402
152-156 F5.3 0.1nm SiIV-1402 [0.006/0.65]? Rest-frame SIVλ1402
equivalent width (2)
158-162 F5.3 0.1nm e_SiIV-1402 [0.003/0.04]? Uncertainty in SiIV-1402
164 A1 --- f_SiIV-1402 Flag SiIV-1402 (3)
166 A1 --- l_CIV-1548 Limit flag on CIV-1548
167-171 F5.3 0.1nm CIV-1548 [0.004/1]? Rest-frame CIVλ1548
equivalent width (2)
173-177 F5.3 0.1nm e_CIV-1548 [0.002/0.08]? Uncertainty in CIV-1548
179-181 A3 --- f_CIV-1548 Flag(s) on CIV-1548 (3)
183 A1 --- l_CIV-1550 Limit flag on CIV-1550
184-188 F5.3 0.1nm CIV-1550 [0.003/0.7]? Rest-frame CIVλ1550
equivalent width (2)
190-194 F5.3 0.1nm e_CIV-1550 [0.002/0.08]? Uncertainty in CIV-1550
196 A1 --- f_CIV-1550 Flag on CIV-1550 (3)
198-199 I2 --- FNum [11/84] Corresponding figure number
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Note (1): Note as follows:
a = Proximate absorber within 5000km/s of the QSO redshift.
b = See notes on this system in Appendix C.
Note (2): In units of Angstroms.
Note (3): Flag as follows:
c = Blended line;
d = Measurement from a de-blended line;
e = Missing data due to contamination from telluric residuals;
f = MgIIλ2796 equivalent width derived from MgIIλ2803 line;
g = CIVλ1548 equivalent width derived from CIVλ1550 line;
h = Formal detection with large error. Should be treated with caution.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 10-Mar-2021