J/ApJ/872/81 The COS CGM Compendium (CCC). II. Lyman limit syst. (Wotta+, 2019)
The COS CGM Compendium.
II. Metallicities of the partial and Lyman limit systems at z≤1.
Wotta C.B., Lehner N., Howk J.C., O'Meara J.M., Oppenheimer B.D.,
Cooksey K.L.
<Astrophys. J., 872, 81 (2019)>
=2019ApJ...872...81W 2019ApJ...872...81W
ADC_Keywords: Spectra, ultraviolet; Intergalactic medium; Abundances; Redshifts;
H I data
Keywords: cosmology: observations ; galaxies: abundances ; galaxies: evolution ;
galaxies: halos ; intergalactic medium ; quasars: absorption lines
Abstract:
We present the results from our COS circumgalactic medium (CGM)
compendium (CCC), a survey of the CGM at z≲1 using HI-selected
absorbers with 15<logNHI<19. We focus here on 82 partial Lyman limit
systems (pLLSs, 16.2≤logNHI<17.2) and 29 LLSs (17.2≤logNHI<19).
Using Bayesian techniques and Markov Chain Monte Carlo sampling of a
grid of photoionization models, we derive the posterior probability
distribution functions (PDFs) for the metallicity of each absorber in
CCC. We show that the combined pLLS metallicity PDF at z≲1 has two
main peaks at [X/H]~-1.7 and -0.4, with a strong dip at [X/H]~-1. The
metallicity PDF of the LLSs might be more complicated than a unimodal
or bimodal distribution. The pLLSs and LLSs probe a similar range of
metallicities -3≲[X/H]≲+0.4, but the fraction of very metal-poor
absorbers with [X/H]≲-1.4 is much larger for the pLLSs than the LLSs.
In contrast, absorbers with logNHI≥19 have mostly -1≲[X/H]≲0 at
z≲1. The metal-enriched gas probed by pLLSs and LLSs confirms that
galaxies that have been enriching their CGM over billions of years.
Surprisingly, despite this enrichment, there is also abundant
metal-poor CGM gas (41%-59% of the pLLSs have [X/H]≲-1.4),
representing a reservoir of near-pristine gas around z≲1 galaxies. We
compare our empirical results to recent cosmological zoom simulations,
finding some discrepancies, including an overabundance of metal-
enriched CGM gas in simulations.
Description:
In Paper I (Lehner+, 2018, J/ApJ/866/33), we assembled a sample of 224
HI-selected absorbers with 15<logNHI<19 at z≲1. The data were
retrieved from the HST/COS G130M and/or G160M archive with
supplementary ground-based observations of MgII and FeII with
high-resolution Keck/HIRES and VLT/UVES spectra. An additional 39
absorbers are available from our two first surveys (Lehner+, 2013,
J/ApJ/770/138 and Wotta+ 2016ApJ...831...95W 2016ApJ...831...95W). Most of these extra
absorbers were observed with HST/STIS, FUSE, and HST/COS G140L.
In this paper, we focus solely on the partial Lyman limit systems
(pLLSs) and LLSs.
As part of our survey, we acquired new high-resolution observations of
MgII (and FeII; see Paper I) for 113 absorbers. Data for three of
these absorbers were also initially obtained with low-resolution
spectra (R∼4000).
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table6.dat 113 111 Metallicities of the partial Lyman limit systems
(pLLSs) and LLSs in the COS circumgalactic medium
(CGM) Compendium (CCC) sample
table9.dat 67 570 Summary of the MCMC inputs for the 82 pLLSs
(16.2≤logNHI<17.2)
table10.dat 67 144 Summary of the MCMC inputs for the 29 LLSs
(17.2≤logNHI<19)
--------------------------------------------------------------------------------
See also:
B/hst : HST Archived Exposures Catalog (STScI, 2007)
J/ApJS/164/1 : IGM absorbers toward HE 0226-4110 (Lehner+, 2006)
J/ApJ/636/610 : Damped Lyα systems at z<1.65 (Rao+, 2006)
J/ApJS/168/213 : Ionization states and cooling efficiencies (Gnat+, 2007)
J/ApJ/676/262 : PKS1302-102 intergalactic absorption system (Cooksey+, 2008)
J/ApJS/177/39 : Survey of low-redshift OVI absorbers (Tripp+, 2008)
J/ApJ/700/1299 : Gas-phase element depletions in the ISM (Jenkins, 2009)
J/ApJS/193/28 : Galaxy survey around 20 UV-bright quasars (Prochaska+, 2011)
J/ApJ/736/42 : HST QSO Catalog (Ribaudo+, 2011)
J/ApJ/740/91 : Lyα & 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/ApJ/794/156 : MgII/FeII absorption profile for z<1.4 gal. (Rubin+, 2014)
J/MNRAS/449/3263 : Extended galaxy halo gas through HI and OVI (Johnson+, 2015)
J/ApJ/804/79 : HST/COS obs. of QSOs within 600kpc of M31 (Lehner+, 2015)
J/ApJ/833/270 : HI-selected-Lyman limit systems (Glidden+, 2016)
J/ApJ/833/283 : HI-selected Lyman limit systems (Lehner+, 2016)
J/MNRAS/458/4074 : UVES Advanced Data Products QSO Sample. VI. (Quiret+, 2016)
J/ApJS/230/6 : HST -COS & -STIS absorption-line spec. II. (Keeney+, 2017)
J/MNRAS/471/3428 : Damped Lyman Alpha systems equivalent width (Rao+, 2017)
J/A+A/607/A48 : AGN data and absorption-line measurements (Richter+, 2017)
J/A+A/606/A71 : dSph RGB abundance and velocities (Skuladottir+, 2017)
J/A+A/614/A149 : 417 Gal. bulge red giant O & Zn abund. (da Silveira+, 2018)
J/A+A/611/A76 : DLAS dust-corrected metallicity (De Cia+, 2018)
J/ApJ/866/33 : The COS CGM compendium. I. Initial results (Lehner+, 2018)
Byte-by-byte Description of file: table6.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 19 A19 --- Name Sightline name (JHHMMSS.ss+DDMMSS.s)
21- 28 F8.6 --- zabs [0.08/1.1] Absorber redshift
30- 34 F5.2 [cm-2] logNHI [16.2/19] log HI column density
36- 39 F4.2 [cm-2] e_logNHI [0.01/0.3] logNHI uncertainty
41 A1 --- lb[X/H] Limit flag on b_[X/H]
43- 47 F5.2 [-] b_[X/H] [-4.74/0.03] 68% CI lower bound on [X/H]
49 A1 --- l_[X/H] Limit flag on [X/H]
51- 55 F5.2 [-] [X/H] [-3.75/1.09] Median value of [X/H]
57 A1 --- lB[X/H] Limit flag on B_[X/H]
59- 63 F5.2 [-] B_[X/H] [-2.75/2.21] 80% CI upper bound on [X/H]
65- 69 F5.2 [-] b_logU [-4.44/-2.28] 68% CI lower bound on logU
71- 75 F5.2 [-] logU [-4.37/-1.75] Median value of ionization
parameter (log U)
76 A1 --- u_logU [:] Uncertainty flag on logU (1)
78- 82 F5.2 [-] B_logU [-4.29/-1.19] 80% CI upper bound on logU
84 A1 --- lb[C/a] Limit flag on b_[C/a]
86- 90 F5.2 [-] b_[C/a] [-0.96/0.74]? 68% CI lower bound on [C/a]
92 A1 --- l_[C/a] Limit flag on [C/a]
94- 98 F5.2 [-] [C/a] [-0.76/0.9]? Median value of [C/α]
99 A1 --- u_[C/a] [:] Uncertainty flag on [C/a]
101 A1 --- lB[C/a] Limit flag on B_[C/a]
103-107 F5.2 [-] B_[C/a] [-0.49/0.98]? 80% CI upper bound on [C/a]
109-110 I2 --- Fig24 [1/82]? Absorber identification number on
Figure 24 (82 images); column added by CDS
112-113 I2 --- Fig26 [1/29]? Absorber identification number on
Figure 26 (29 images); column added by CDS
--------------------------------------------------------------------------------
Note (1): When a colon is present after the median value of log U, this
implies that a Gaussian prior was used to determine the properties of
the absorber (see Section 3.3.2).
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table9.dat table10.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 19 A19 --- Name Sightline name (JHHMMSS.ss+DDMMSS.s)
20 A1 --- --- [_]
21- 29 A9 --- ID Identifier (z{zabs} within Name)
31- 38 F8.6 --- zabs [0.08/1.1] Redshift from absorption in Ion
40- 47 F8.6 --- e_zabs [1e-06/0.001] Uncertainty in zabs
49- 53 A5 --- Ion Ion identifier
55- 59 F5.2 [cm-2] logN [11/19] log column density in Ion
61- 64 F4.2 [cm-2] e_logN [0.01/0.6] Uncertainty in logN
66- 67 I2 --- Flag [-3/0]? Detection flag code (1)
--------------------------------------------------------------------------------
Note (1): Flag as follows:
0 = detection;
-1 = upper limit (non-detection);
-2 = lower limit due to saturation of the line.
--------------------------------------------------------------------------------
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 This catalog.
Lehner et al. Paper III. 2019ApJ...887....5L 2019ApJ...887....5L
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 03-Aug-2020