J/ApJ/887/5 COS CGM compendium (CCC). III. z≤1 Lyα syst. (Lehner+, 2019)
The COS CGM compendium.
III. Metallicity and physical properties of the cool circumgalactic medium
at z≤1.
Lehner N., Wotta C.B., Howk J.C., O'Meara J.M., Oppenheimer B.D.,
Cooksey K.L.
<Astrophys. J., 887, 5 (2019)>
=2019ApJ...887....5L 2019ApJ...887....5L
ADC_Keywords: QSOs; Spectra, ultraviolet; H I data; Redshifts; Abundances;
Intergalactic medium
Keywords: Quasar absorption line spectroscopy ; Metallicity ;
Galaxy environments ; Circumgalactic medium
Abstract:
We characterize the metallicities and physical properties of cool,
photoionized gas in a sample of 152 z≤1 strong Lyα forest
systems (SLFSs, absorbers with 15<logNHI<16.2). The sample is drawn
from our Cosmic Origins Spectrograph (COS) circumgalactic medium
compendium (CCC), an ultraviolet survey of HI-selected circumgalactic
gas around z≤1 galaxies that targets 261 absorbers with
15<logNHI<19. We show that the metallicity probability distribution
function of the SLFSs at z≤1 is unimodal, skewed to low metallicities
with a mean and median of [X/H]=-1.47 and -1.18dex. Very metal-poor
gas with [X/H]<-1.4 represents about half of the population of
absorbers with 15<logNHI≤18, while it is rare at higher NHI.
Thus, there are important reservoirs of primitive (though not
pristine) diffuse ionized gas around z≤1 galaxies. The photoionized
gas around z≤1 galaxies is highly inhomogeneous based on the wide
range of metallicities observed (-3≤[X/H]≤+0.4) and the fact that
there are large metallicity variations (factors of 2 to 25) for most
of the closely spaced absorbers (Δv≤300km/s) along the same
sightlines. These absorbers show a complex evolution with redshift and
HI column density, and we identify subtle cosmic evolution effects
that affect the interpretation of metallicity distributions and
comparison with other absorber samples. We discuss the physical
conditions and cosmic baryon and metal budgets of the CCC absorbers.
Finally, we compare the CCC results to recent cosmological zoom
simulations and explore the origins of the 15<logNHI<19 absorbers
within the Evolution and Assembly of GaLaxies and their Environments
(EAGLE) high-resolution simulations.
Description:
As presented in Paper I (Lehner+, 2018, J/ApJ/866/33), the QSO spectra
for the strong Lyα forest system (SLFS) sample were retrieved
from the HST/COS G130M and/or G160M archive. Several of these QSOs
were also observed from the ground with high-resolution Keck/HIRES and
Very Large Telescope (VLT)/UVES spectra.
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table2.dat 115 261 Metallicities of the absorbers in the
circumgalactic medium compendium (CCC) sample
table5.dat 124 261 Physical properties of the CCC sample
table8.dat 74 2248 Summary of the MCMC inputs for the absorbers in CCC
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See also:
J/ApJ/559/654 : Lyα absorption systems. V. (Chen+, 2001)
J/ApJ/635/123 : The SDSS-DR3 damped Lyα survey (Prochaska+, 2005)
J/ApJ/676/262 : PKS1302-102 intergalactic absorption system (Cooksey+, 2008)
J/ApJ/721/1 : Keck ESI observations of Lyα systems (Penprase+, 2010)
J/ApJ/718/392 : SDSS Lyman limit systems at z∼3.5 (Prochaska+, 2010)
J/ApJS/195/16 : HST survey for Lyman limit systems. I. (O'Meara+, 2011)
J/ApJ/740/91 : Lyα and OVI in galaxies around QSOs (Prochaska+, 2011)
J/ApJ/755/89 : Metallicities of damped Lyα systems (Rafelski+, 2012)
J/ApJ/770/138 : Metallicities of Lyman limit systems and DLA (Lehner+, 2013)
J/ApJ/765/137 : HST survey for Lyman limit systems. II. (O'Meara+, 2013)
J/MNRAS/445/2061 : Absorption in multiphase circumgal. medium (Liang+, 2014)
J/MNRAS/437/2017 : HI-galaxy cross-correlation at z≲1 (Tejos+, 2014)
J/ApJ/817/111 : HST/COS survey of z<0.9 AGNs. I. (Danforth+, 2016)
J/ApJ/833/270 : Lyman limit system metallicities (Glidden+, 2016)
J/ApJ/833/283 : HI-selected Lyman limit system metallicities (Lehner+, 2016)
J/MNRAS/458/4074 : UVES Advanced Data Products QSO Sample. VI. (Quiret+, 2016)
J/ApJS/230/6 : HST -COS & -STIS absorption-line sp. II. (Keeney+, 2017)
J/ApJ/866/33 : The COS CGM compendium. I. Initial results (Lehner+, 2018)
J/ApJ/872/81 : COS CGM Compendium (CCC). II. Lyman syst. (Wotta+, 2019)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 19 A19 --- QSO QSO identifier (JHHMMSS.ss+DDMMSS.s)
21 A1 --- Prox [a] Proximity flag (1)
23- 30 F8.6 --- zabs [0.08/1.1] Redshift of the absorber
32- 36 F5.2 [cm-2] logNHI [15/19] log H I column density
38- 41 F4.2 [cm-2] e_logNHI [0.01/0.3] Uncertainty in logNHI
43 A1 --- lb[X/H] Limit flag on lo[X/H]
45- 49 F5.2 [-] b_[X/H] [-4.75/0.11] Lower bound in [X/H] (2)
51 A1 --- l_[X/H] Limit flag on [X/H]
53- 57 F5.2 [-] [X/H] [-3.76/1.1] Median log absorber metallicity
59 A1 --- lB[X/H] Limit flag on up[X/H]
61- 65 F5.2 [-] B_[X/H] [-2.9/2.3] Upper bound in [X/H] (2)
67 A1 --- lblogU Limit flag on lologU
69- 73 F5.2 [-] b_logU [-4.5/-0.79] Lower bound in logU (2)
75 A1 --- l_logU Limit flag on logU
77- 81 F5.2 [-] logU [-4.4/-0.65] Median log ionization parameter
82 A1 --- u_logU [:] Prior flag on logU (3)
84 A1 --- lBlogU Limit flag on uplogU
86- 90 F5.2 [-] B_logU [-4.3/-0.6] Upper bound in logU (2)
92 A1 --- lb[C/a] Limit flag on lo[C/a]
94- 98 F5.2 [-] b_[C/a] [-0.97/0.74]? Lower bound in [C/a] (2)
100 A1 --- l_[C/a] Limit flag on [C/a]
102-106 F5.2 [-] [C/a] [-0.84/0.9]? Median log C/α abundance
ratio
107 A1 --- u_[C/a] [:] Prior flag in [C/a] (4)
109 A1 --- lB[C/a] Limit flag on up[c/a]
111-115 F5.2 [-] B_[C/a] [-0.66/0.98]? Upper bound in [C/a] (2)
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Note (1):
a = Proximate absorbers, i.e., absorbers with
Δv=(zem-zabs)/(1+zabs)c<3000km/s (see Paper I;
Lehner+, 2018, J/ApJ/866/33).
Note (2): The lower to upper bounds for each quantity represent the 68% CI for
detections and the 80% CI for the upper or lower limits.
Note (3): Implies that a logU Gaussian prior was used to determine the
properties of the absorber.
Note (4): Implies that a [C/alpha] prior was used to determine the
properties of the absorber.
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 19 A19 --- QSO QSO identifier (JHHMMSS.ss+DDMMSS.s)
21- 28 F8.6 --- zabs [0.08/1.1] Redshift of the absorber
30- 34 F5.2 [cm-2] logNHI [15/19] log neutral hydrogen column density
36- 39 F4.2 [cm-2] e_logNHI [0.01/0.3] Uncertainty in logNHI
41- 45 F5.2 [cm-2] b_logNH [16.7/21.42] Lower bound in logNH (1)
47- 51 F5.2 [cm-2] logNH [17/21.53] Median log hydrogen column density
53- 57 F5.2 [cm-2] B_logNH [17.2/21.6] Upper bound in logNH (1)
59 A1 --- lblognH Limit flag on b_lognH
61- 65 F5.2 [cm-3] b_lognH [-4.5/-0.88] Lower bound in lognH (1)
67 A1 --- l_lognH Limit flag on lognH
69- 73 F5.2 [cm-3] lognH [-4.5/-0.8] Median log hydrogen density
74 A1 --- u_lognH [:] Prior flag on lognH (2)
76 A1 --- lBlognH Limit flag on uplognH
78- 82 F5.2 [cm-3] B_lognH [-4.32/-0.73] Upper bound in lognH (1)
84- 87 F4.2 [K] b_logT [2.1/4.75] Lower bound in logT (1)
89- 92 F4.2 [K] logT [2.6/4.77] Median log temperature
94- 97 F4.2 [K] B_logT [3.75/4.77] Upper bound in logT (1)
99-106 F8.2 kpc b_Scale [0/19869] Lower bound on Scale (1)
108-115 F8.2 kpc Scale [0/32058] Median linear scale
117-124 F8.2 kpc B_Scale [0/37862] Upper bound on Scale (1)
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Note (1): The lower to upper bounds for each quantity represent the 68% CI for
detections and 80% CI for the upper or lower limits.
Note (2): Implies that a logU Gaussian prior was used to determine the
properties of the absorber (see Section 2.2).
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Byte-by-byte Description of file: table8.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 A5 --- Type Absorber type (1)
7- 25 A19 --- QSO Quasar identifier (JHHMMSSss+DDMMSS.s)
26- 35 A10 --- ID Unique identifier within QSO names
(with zN.NNNNNN = zabs)
37- 44 F8.6 --- zabs [0.08/1.1] Redshift of the absorber
46- 53 F8.6 --- e_zabs [1e-6/0.001] Uncertainty in zabs
55- 60 A6 --- Ion Ion identifier
62- 66 F5.2 [cm-2] logN [10.87/19] log Ion column density
68- 71 F4.2 [cm-2] e_logN [0.01/0.6] Uncertainty in logN
73- 74 I2 --- Flag [-3/0]? Column density flag (2)
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Note (1): Type as follows:
SLFSs = strong Lyα forest systems (1535 occurrences)
pLLSs = partial Lyman limit systems (572 occurrences)
LLSs = Lyman limit systems (141 occurrences)
Note (2): Flag as follows:
0 = detection (not saturated or contaminated; 648 occurrences);
-1 = upper limit;
-2 = lower limit (due to saturation of the line).
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History:
From electronic version of the journal
References:
Lehner et al. Paper I. 2018ApJ...866...33L 2018ApJ...866...33L Cat. J/ApJ/866/33
Wotta et al. Paper II. 2019ApJ...872...81W 2019ApJ...872...81W Cat. J/ApJ/872/81
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 05-May-2021