J/ApJ/788/119 Properties of the highly ionized gas of quasars (Lehner+, 2014)
Galactic and circumgalactic O VI and its impact on the cosmological metal
and baryon budgets at 2<z≲3.5.
Lehner N., O'Meara J.M., Fox A.J., Howk J.C., Prochaska J.X., Burns V.,
Armstrong A.A.
<Astrophys. J., 788, 119 (2014)>
=2014ApJ...788..119L 2014ApJ...788..119L (SIMBAD/NED BibCode)
ADC_Keywords: QSOs ; Redshifts ; Atomic physics ; Line Profiles
Keywords: galaxies: halos - galaxies: high-redshift - galaxies: starburst -
intergalactic medium - quasars: absorption lines
Abstract:
We present the first results from our NASA Keck Observatory Database
of Ionized Absorbers toward Quasars (KODIAQ) survey which aims to
characterize the properties of the highly ionized gas of galaxies and
their circumgalactic medium (CGM) at 2<z<4. We select absorbers
optically thick at the Lyman limit (τLL>1, logNHI>17.3) as
probes of these galaxies and their CGM where both transitions of the O VI
doublet have little contamination from the Lyα, β forests.
We found 20 absorbers that satisfy these rules: 7 Lyman limit systems
(LLSs), 8 super-LLSs (SLLSs) and 5 damped Lyα (DLAs). The O VI
detection rate is 100% for the DLAs, 71% for the LLSs, and 63% for the
SLLSs. When O VI is detected, log(N_O VI_)=14.9±0.3, an average
O VI column density substantially larger and with a smaller dispersion
than found in blind O VI surveys at similar redshifts. Strong O VI
absorption is therefore nearly ubiquitous in the CGM of z∼2-3 galaxies.
The total velocity widths of the O VI profiles are also large
(200≤ΔυO VI_≤400 km/s). These properties are
quite similar to those seen for O VI in low-z star-forming galaxies,
and therefore we hypothesize that these strong CGM O VI absorbers
(with τLL>1) at 2<z≲3.5 also probe outflows of star-forming
galaxies. The LLSs and SLLSs with no O VI absorption have properties
consistent with those seen in cosmological simulations tracing cold
streams feeding galaxies. When the highly ionized (Si IV and O VI) gas
is taken into account, we determine that the τLL>1 absorbers
could contain as much as 3%-14% of the cosmic baryon budget at z∼2-3,
only second to the Lyα forest. We conservatively show that
5%-20% of the metals ever produced at z∼2-3 are in form of highly
ionized metals ejected in the CGM of galaxies.
Description:
All data in this sample were acquired with the HIgh Resolution Echelle
Spectrometer (HIRES; Vogt et al. 1994SPIE.2198..362V 1994SPIE.2198..362V) on the Keck I
telescope on Mauna Kea. These data were obtained by different PIs from
different institutions with Keck access, and hundreds of spectra of
QSOs at 0<z<6, most being at z∼2-4, were collected. This provides one
of the richest assortments of high-z QSO spectra at high spectral
resolution (6-8 km/s) and high signal-to-noise (many with S/N>20-50).
We were awarded a NASA Astrophysics Data Analysis Program (ADAP) grant
(PI Lehner) to perform the data reduction and coaddition of the individual
exposures of the entire KOA QSO database to study in detail the highly
ionized plasma associated with τLL>1 absorbers at 2<z<4. We plan
to release the entire KODIAQ database to the scientific community in 2015.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 77 20 Data Sample Summary
table8.dat 67 256 Results from the Profile Fits
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See also:
VII/23 : Absorption Lines in QSO Spectra (Ellis+ 1978)
VII/69 : Asiago Catalogue of QSOs (Barbieri+ 1983)
J/AJ/112/62 : Quasar absorption-line systems (Tanner+ 1996)
J/ApJ/508/200 : QSO low-z Lyα absorbers (Tripp+, 1998)
J/MNRAS/346/1103 : Redshifts of damped Lymanα absorbers (Peroux+, 2003)
J/ApJ/635/123 : The SDSS-DR3 damped Lyα survey (Prochaska+, 2005)
J/ApJS/177/39 : Survey of low-redshift OVI absorbers (Tripp+, 2008)
J/ApJ/775/78 : Lyman limit absorption systems in z∼3 QSOs
(Fumagalli+, 2013)
J/AJ/150/111 : KODIAQ DR1 (O'Meara+, 2015)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 11 A11 --- ID Source identifier
13- 14 I2 h RAh Hour of Right Ascension (J2000)
16- 17 I2 min RAm Minute of Right Ascension (J2000)
19- 23 F5.2 s RAs Second of Right Ascension (J2000)
25 A1 --- DE- Sign of the Declination (J2000)
26- 27 I2 deg DEd Degree of Declination (J2000)
29- 30 I2 arcmin DEm Arcminute of Declination (J2000)
32- 35 F4.1 arcsec DEs Arcsecond of Declination (J2000)
37- 51 A15 --- PI The original PI who acquired the data
53- 54 I2 10+3 Res [36/72] Spectral resolution
55 A1 --- n_Res [d] Note on Res (1)
57- 58 I2 --- S/N [6/54] Signal-to-noise ratio (2)
60- 64 F5.3 --- z QSO redshift
66- 72 F7.5 --- zabs Absorber redshift (3)
74- 77 F4.1 10+3km/s deltav Velocity difference (4)
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Note (1): Note as follows:
d = Also, R=36000 in the red (C IV, as well Si IV at high S/N).
Note (2): Signal to noise (S/N) near O VI λ1031; generally, the S/N is
higher at higher wavelengths.
Note (3): The absorber redshift is determined by the centroid relative to the
neutral (e.g., H I or O I) or low ionization (e.g., C II or Si II) species
and will not generally match the exact redshift of the centroid to the
observed O VI.
Note (4): deltav=c(zem-zabs)/(1+zabs).
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Byte-by-byte Description of file: table8.dat
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Bytes Format Units Label Explanations
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1- 11 A11 --- ID Source identifier
13- 19 F7.5 --- z Redshift of the absorber
21 A1 --- f_z [ip] Flag on z (1)
23- 27 A5 --- Ion Fitted ion
29- 30 I2 --- Num [1/16] Component number
32- 37 F6.1 km/s Vel Velocity
39- 42 F4.1 km/s e_Vel Uncertainty in Vel
44- 48 F5.1 km/s b Doppler parameter
50- 53 F4.1 km/s e_b Uncertainty in b
55- 59 F5.2 [cm-2] logN Log column density
61- 64 F4.2 [cm-2] e_logN Uncertainty in logN
67 I1 --- Flag [0/3]? Fit flag (2)
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Note (1): Flag as follows:
i = intervening;
p = proximate.
Note (2): Flag as follows:
0 = result is robust;
1 = uncertain owing to the complexity of the absorption profile or on the
necessity to rely on only one transition of the doublet;
2 = uncertain owing to the relative low S/N;
3 = uncertain results because the component is saturated in both transitions
of the fitted doublet.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Tiphaine Pouvreau [CDS] 12-Jul-2017