J/MNRAS/502/4009 Sub-damped Lyman α systems in XQ-100 II (Berg+, 2021)
Sub-damped Lyman α systems in the XQ-100 survey - II.
Chemical evolution at 2.4=<z=<4.3.
Berg T.A.M., Fumagalli M., D'Odorico V., Ellison S.L., Lopez S.,
Becker G.D., Christensen L., Cupani G., Denney K.D., Sanchez-Ramirez R.,
Worseck G.
<Mon. Not. R. Astron. Soc., 502, 4009-4025 (2021)>
=2021MNRAS.502.4009B 2021MNRAS.502.4009B (SIMBAD/NED BibCode)
ADC_Keywords: QSOs ; Redshifts ; Abundances, peculiar ; Spectra, optical
Keywords: galaxies: high-redshift - galaxies: ISM - quasars: absorption lines
Abstract:
We present the measured gas-phase metal column densities in 155
sub-damped Ly α systems (subDLAs) with the aim to investigate
the contribution of subDLAs to the chemical evolution of the Universe.
The sample was identified within the absorber-blind XQ-100 quasar
spectroscopic survey over the redshift range 2.4=<zabs=<4.3. Using
all available column densities of the ionic species investigated
(mainly CIV, SiII, MgII, SiIV, AlII, FeII, CII, and OI; in order of
decreasing detection frequency), we estimate the ionization-corrected
gas-phase metallicity of each system using Markov chain Monte Carlo
techniques to explore a large grid of CLOUDY ionization models.
Without accounting for ionization and dust depletion effects, we find
that the HI-weighted gas-phase metallicity evolution of subDLAs is
consistent with damped Ly α systems (DLAs). When ionization
corrections are included, subDLAs are systematically more metal poor
than DLAs (between ∼0.5σ and ∼3σ significance) by up to
∼1.0dex over the redshift range 3=<zabs=<4.3. The correlation of gas
phase [Si/Fe] with metallicity in subDLAs appears to be consistent
with that of DLAs, suggesting that the two classes of absorbers have a
similar relative dust depletion pattern. As previously seen for Lyman
limit systems, the gas phase [C/O] in subDLAs remains constantly solar
for all metallicities indicating that both subDLAs and Lyman limit
systems could trace carbon-rich ejecta, potentially in circumgalactic
environments.
Description:
The XQ-100 Legacy Survey (Lopez et al. 2016A&A...594A..91L 2016A&A...594A..91L) observed
100 QSO sightlines between redshifts 3.5=<zem=<4.5 with the
X-Shooter Spectrograph (Vernet et al. 2011A&A...536A.105V 2011A&A...536A.105V) on the Very
Large Telescope (VLT). Each QSO was observed for ∼0.5 or ∼1h based on
the QSO's brightness; providing a median signal-to-noise ratio of ∼30
per pixel. As the QSOs were purposefully chosen to be blind to any
intervening absorption line systems, the XQ-100 data set provides a
randomly selected sample of subDLAs and DLAs to assess their
cosmological contribution to the evolution of neutral gas at redshifts
modestly probed in past surveys (Sanchez-Ramirez et al.
2016MNRAS.456.4488S 2016MNRAS.456.4488S, Cat. J/MNRAS/456/4488; Berg et al.
2016MNRAS.463.3021B 2016MNRAS.463.3021B, 2017MNRAS.464L..56B 2017MNRAS.464L..56B, Cat. J/MNRAS/464/L56,
2019MNRAS.488.4356B 2019MNRAS.488.4356B; Christensen et al. 2017A&A...608A..84C 2017A&A...608A..84C).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 84 5041 XQ-100 subDLA metal column densities
table3.dat 86 155 XQ-100 subDLA metallicities
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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- 10 A10 --- Name Name of the quasar sightline (JHHMM+DDMM)
12- 18 F7.5 --- zabs Redshift of the absorber
20- 24 A5 --- Ion Ionic species
26- 29 I4 0.1nm lambda ? Wavelength of the line
31- 34 I4 km/s vmin ? Starting velocity of the AODM
integration
36- 39 I4 km/s vmax ? End velocity of the AODM integration
41- 45 F5.2 [cm-2] logN ? Logarithm of the column density for the
absorption line
47- 52 F6.2 [cm-2] e_logN ? Error on logN
54- 55 I2 --- f_logN ? Flag indicating whether the absorption
is adopted for logN (1)
57- 61 F5.2 [cm-2] logNadop ? Logarithm of the adopted column density
63- 66 F4.2 [cm-2] e_logNadop ? Error on logNadop
68 I1 --- f_logNadop ? Flag indicating whether the absorption
is adopted for logNadop (1)
70- 74 F5.2 [cm-2] logNadopIC ? Logarithm of the adopted column density
with ionization correction
76- 79 F4.2 [cm-2] e_logNadopIC ? Lower error on logNadopIC
81- 84 F4.2 [cm-2] E_logNadopIC ? Upper error on logNadopIC
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Note (1): Flag as follows:
1 = absorption adopted
2 = absorption saturated or lower limit
4 = absorption undetected
8 = absorption blended
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- Name Name of the quasar sightline (JHHMM+DDMM)
12- 18 F7.5 --- zabs Redshift of the absorber
20- 24 F5.2 [cm-2] logNHI Logarithm of the HI column density
26- 29 F4.2 [cm-2] e_logNHI Error on logNHI
31 A1 --- l_[M/H] Limit flag on [M/H]
33- 37 F5.2 [-] [M/H] Total gas-phase metallicity of the system
39- 42 F4.2 [-] e_[M/H] ? Error on [M/H]
44- 47 A4 --- Ion Ion used to compute [M/H]
49- 53 F5.2 [-] [M/H]IC Total gas-phase metallicity of the system
with ionization correction
55- 59 F5.2 [-] b_[M/H]IC Lower bound on [M/H]IC
61- 65 F5.2 [-] B_[M/H]IC Upper bound on [M/H]IC
67- 71 F5.2 [cm-2] lognH Logarithm of the gas density nH
73- 77 F5.2 [cm-2] b_lognH Lower bound on lognH
79- 83 F5.2 [cm-2] B_lognH Upper bound on lognH
85- 86 A2 --- Sample Sample name (1)
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Note (1): We split the XQ-100 subDLA absorbers into two samples: the full
catalogue of subDLAs (abbreviated FS) and those with at least one
confirmed detection of a metal species from the method outlined in
Section 2.2 (referred to as the metal-selected sample, MS)
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History:
From electronic version of the journal
References:
Berg et al., Paper I 2019MNRAS.488.4356B 2019MNRAS.488.4356B
(End) Ana Fiallos [CDS] 30-Oct-2023