# The ESO UVES advanced data products quasar sample - VI. Sub-damped Lyman alpha metallicity measurements and the circumgalactic medium

S. Quiret, C. Peroux, T. Zafar, V. P. Kulkarni, E. B. Jenkins, B. Milliard, H. Rahmani, A. Popping, S. M. Rao, D. A. Turnshek, et al.

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S. Quiret, C. Peroux, T. Zafar, V. P. Kulkarni, E. B. Jenkins, et al.. The ESO UVES advanced data products quasar sample - VI. Sub-damped Lyman alpha metallicity measurements and the circumgalactic medium. Monthly Notices of the Royal Astronomical Society, 2016, 458 (4), pp.4074-4121. 10.1093/mnras/stw524. hal-01440154

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# The ESO UVES advanced data products quasar sample – VI. Sub-damped Lyman α metallicity measurements and the circumgalactic medium

S. Quiret,<fnref n="1" />* C. Péroux,<fnref n="1" />* T. Zafar,<fnref n="2" /> V. P. Kulkarni,<fnref n="3" /> E. B. Jenkins,<fnref n="4" /> B. Milliard,<fnref n="1" /> H. Rahmani,<fnref n="1" /> A. Popping,<fnref n="5" /> S. M. Rao,<fnref n="6" /> D. A. Turnshek<fnref n="6" /> and E. M. Monier<fnref n="7" />

Accepted 2016 March 2. Received 2016 March 2; in original form 2015 June 26

## ABSTRACT

The circumgalactic medium (CGM) can be probed through the analysis of absorbing systems in the line of sight to bright background quasars. We present measurements of the metallicity of a new sample of 15 sub-damped Lyman α absorbers (sub-DLAs, defined as absorbers with $19.0 < \log N(HI) < 20.3$) with redshift $0.584 \le z_{abs} \le 3.104$ from the ESO Ultra-Violet Echelle Spectrograph (UVES) Advanced Data Products Quasar Sample (EUADP). We combine these results with other measurements from the literature to produce a compilation of metallicity measurements for 92 sub-DLAs as well as a sample of 362 DLAs. We apply a multi-element analysis to quantify the amount of dust in these two classes of systems. We find that either the element depletion patterns in these systems differ from the Galactic depletion patterns or they have a different nucleosynthetic history than our own Galaxy. We propose a new method to derive the velocity width of absorption profiles, using the modelled Voigt profile features. The correlation between the velocity width $\Delta V_{90}$ of the absorption profile and the metallicity is found to be tighter for DLAs than for sub-DLAs. We report hints of a bimodal distribution in the [Fe/H] metallicity of low redshift ($z < 1.25$) sub-DLAs, which is unseen at higher redshifts. This feature can be interpreted as a signature from the metal-poor, accreting gas and the metal-rich, outflowing gas, both being traced by sub-DLAs at low redshifts.

**Key words:** galaxies: abundances – galaxies: evolution – galaxies: formation – intergalactic medium – galaxies: ISM – quasars: absorption lines.

## 1 INTRODUCTION

In-depth studies of galaxy evolution require an understanding of the complex processes occurring at the interface of the galaxy and its nearby environment, the circum-galactic medium (CGM).

On the one hand, the star formation process is believed to be fed in galaxies via accretion mechanisms (Rees & Ostriker 1977; White & Rees 1978; Prochaska & Wolfe 2009; Bauermeister, Blitz & Ma 2010). For galaxies with masses typically below $\sim 10^{11-12} M_{\odot}$, the accreting gas follows cold flows ($T \sim 10^4-5 K$) while for more massive galaxies, a second mode of accretion appears, the ‘hot

mode', where the gas is shock heated near the virial temperature ($T \sim 10^6 K$) (Rees & Ostriker 1977; Silk 1977; White & Rees 1978; Birnboim & Dekel 2003; Kereš et al. 2005; Dekel & Birnboim 2006; Ocvirk, Pichon & Teyssier 2008). Simulations show that about 40 per cent of the accretion may be genuinely smooth (Genel et al. 2010). These modes also differ in metallicity (Fumagalli et al. 2011; Shen et al. 2013). Indeed, Ocvirk et al. (2008) showed that the ‘cold mode’ accreting gas can reach metallicities up to tenth solar, while the hot mode accreting gas metallicities are usually lower and are highly dependent on the distance to the centre of the galaxy and on how well the gas is mixed. These accreting streams may also provide the galaxy with additional angular momentum (Fall & Efstathiou 1980). Observational evidences for accretion have been challenging to gather due to the low surface brightness and low

<footnote n="1">¹Aix Marseille Université, CNRS, LAM (Laboratoire d'Astrophysique de Marseille) UMR 7326, F-13388 Marseille, France</footnote>

<footnote n="2">²European Southern Observatory, Karl-Schwarschild-Strasse 2, D-85748 Garching, Germany</footnote>

<footnote n="3">³University of South Carolina, Department of Physics and Astronomy, Columbia, SC 29208 USA</footnote>

<footnote n="4">⁴Princeton University Observatory, Princeton, NJ 08544-1001, USA</footnote>

<footnote n="5">⁵International Centre for Radio Astronomy Research (ICRAR), The University of Western Australia, 35 Stirling Hwy, 6009 Crawley WA, Australia</footnote>

<footnote n="6">⁶Department of Physics and Astronomy and PITTSburgh Particle physics, Astrophysics, and Cosmology Center (PITT PACC), University of Pittsburgh, Pittsburgh, PA 15260, USA</footnote>

<footnote n="7">⁷Department of Physics, The College at Brockport, State University of New York, Brockport, NY 14420, USA</footnote>

<footnote>* E-mail: samuel.quiret@lam.fr (SQ); celine.peroux@lam.fr (CP)</footnote>
filling factor of the infalling gas and its expected low metallicity. Nevertheless, cold accretion has been recently detected in a few objects (Steidel et al. 2000; Martin et al. 2012; Rubin et al. 2012; Bouché et al. 2013). Similarly, early evidences for cold accretion on to quasars have been recently reported by Cantalupo et al. (2014) and Martin et al. (2014).

On the other hand, galaxies release energy and material in their environment (up to ~125 kpc) via supernovae (SNe), stellar winds or active galactic nucleus (AGN) activity. These outflows tend to chemically enriched the IGM (Songaila & Cowie 1996; Simcoe, Sargent & Rauch 2004; Adelberger et al. 2005; Ryan-Weber et al. 2009; D'Odorico et al. 2013; Shull, Danforth & Tilton 2014; Shull et al. 2015), and can regulate the star formation process of galaxies. Indeed, as the gas is released, it will starve the galaxy from fresh gas accreting along the galaxy major axis, quenching the star formation. It will also enhance the star formation by cooling the gas via metal line emissions. Fountains can also be created if the gas does not leave the potential well of the galaxy. In this scenario, the fully metal enriched gas recycles and falls back on to the galactic disc and contribute directly to the star-forming processes as it can cool efficiently. Simulations have shown that fountains dominate the global accretion mechanism for $z \lesssim 1$ galaxies (Oppenheimer et al. 2010). Even though outflows are ubiquitous at all redshifts around star-forming galaxies (Shapley et al. 2003; Martin 2005; Rubin et al. 2014) and their existence is confirmed by signatures of OVI found within the CGM of low-redshift star-forming galaxies (Tumlinson et al. 2011), they remain poorly understood in the context of galaxy formation models.

In the context of emission line study, Bertone et al. (2010a,b) argued that the ionization state of elements provides valuable insight on the physical state of the CGM (mainly its temperature but also its ionizing process) and can be used to study the different feedback processes taking place, including metal pollution of accreting gas via galactic fountains. Fumagalli et al. (2011) also argued that kinematic analysis of absorption lines can be used in addition to the metallicity analysis to distinguish metal-rich outflowing material from metal-poor ($\lesssim 0.01 Z_\odot$) accreting gas. Therefore, the study of metal lines (kinematics, line strengths, ionization states) might be the key diagnostic to observationally disentangle outflows from inflows and assess the level of metal enrichment of the CGM and thus galaxy evolution.

Absorbers observed in background quasar spectra are a tool to probe the low-density gas and its metallicity. Indeed, simulations predict that cold accretion on to galaxies can be observed in absorption via dense H1 absorbing systems with $\log N(H1) > 15.5$ (Faucher-Giguere & Kereš 2011; van de Voort et al. 2012; Shen et al. 2013). They predict that the cold streams could be traced with metal-poor H1 absorption systems, mostly in the Lyman Limit System (LLS) range $17.2 \le \log N(H1) < 19.0$. Recently, Lehner et al. (2013) showed observational evidence for low redshift LLS presenting a bimodal metallicity distribution, which they associated with infalls and outflows. However, the metallicities of LLS depend sensitively on model-dependent ionization corrections, since the LLS gas is highly ionized. This makes it harder to reliably detect the difference between inflows and outflows using the LLS. A more robust way of detecting the metallicity distribution of the gas around galaxies is by using the damped Lyman $\alpha$ (DLA; $\log N(H1) \ge 20.3$) and sub-damped Lyman $\alpha$ (sub-DLA; $19.0 \le \log N(H1) < 20.3$) absorbers. These systems are the primary neutral gas reservoir at $0 < z < 5$ (Storrie-Lombardi & Wolfe 2000; Péroux et al. 2005; Prochaska, Herbert-Fort & Wolfe 2005; Rao, Turnshek & Nestor 2006; Zafar et al. 2013b) and offer the most precise element abundance

measurements in distant galaxies. In particular, at $z \le 2$, Fumagalli et al. (2011) anticipate that almost half of the cross-section in the sub-DLA H1 column density range is due to streams, while at $z \sim 3$, van de Voort et al. (2012) anticipate that it is more than 80 per cent.

In an era of large quasar surveys, with samples of thousands of DLAs available (e.g. Noterdaeme et al. 2012c), sub-DLAs remain little studied. Indeed, at low H1 column densities, one requires a high spectral resolution and high signal-to-noise ratio (SNR) to derive element abundances. The large quasar samples observed with the high resolution spectrographs VLT/UVES (Zafar, Popping & Péroux 2013a) and Keck/HIRES (O'Meara et al. 2015) are therefore crucial tools for our understanding of sub-DLA properties. Here, we present a detailed study of the metallicity and kinematics of a large sample of DLAs and sub-DLAs observed at high resolution with UVES.

The paper is organized as follows. In Section 2 we present the data sample and in Section 3 we describe the abundance measurements. The results are discussed in Section 4 followed by conclusions in Section 5.

# 2 THE DATA

## 2.1 New absorbers

In order to put together a significant sample of sub-DLAs observed at high spectral resolution, we make use of the ESO UVES Advanced Data Products (EUADP) sample from Zafar et al. (2013a). This sample consists of 250 high-resolution ($R \sim 42000$) quasars spectra covering a total of 196 damped absorbers (with $\log N(H1) > 19.0$).

This data set has motivated a number of studies including a report of new H1 systems (Zafar et al. 2013a) and how they can be used to constrained the neutral gas mass density of sub-DLAs in particular (Zafar et al. 2013b), the nucleosynthetic history of Nitrogen (Zafar et al. 2014b) and the low Argon abundances observed in DLAs (Zafar et al. 2014a).

Most of the absorbers in the EUADP sample have their metallicity abundances published in the literature (Péroux et al. 2006a,b, 2008; Zafar et al. 2013b, and reference therein). We present here the analysis of 14 new EUADP sub-DLAs covering a redshift range $0.584 \le z_{abs} \le 3.104$. We also include six new DLAs for completeness. The measurements of H1 column densities and redshifts of each system in the EUADP sample are reported in Zafar et al. (2013a) and references therein.

In addition to these 14 new sub-DLAs from the EUADP sample, we present the UVES spectra of two other systems: one sub-DLA at $z_{abs} = 0.584$ and one DLA at $z_{abs} = 0.647$. These two low-redshift absorbers have been observed with the HST ACS grism from which an estimate of their H1 column densities has been derived (Turnshek et al. 2015). The quasars were subsequently observed with UVES on VLT under the programme 91.A-0300 (PI: C. Péroux) in Service Mode in 2013 August and September. Each object was observed using a combined 346+564 nm setting with two different observations with exposure times lasting 4500 + 3600 s (QSO J0018-0913) and $2 \times 4500$ s (QSO J0132-0823). The data were reduced using the most recent version of the UVES pipeline in MIDAS (uves/5.4.3). Master bias and flat images were constructed using calibration frames taken closest in time to the science frames. The science frames were extracted with the 'optimal' option and corrected to the vacuum heliocentric reference. To combine the resulting spectra, we choose to weight them by the SNR, as for the
<table><caption>**Table 1.** Properties of the 22 quasar absorbers (15 sub-DLAs and 7 DLAs) studied here. The majority of these absorbers are from the EUADP sample (Zafar et al. 2013a), but for the two systems shown in bold which have been observed recently with VLT/UVES by our group (see text for details).</caption><thead><tr><th>QSO name</th><th>Coordinates</th><th>z<sub>em</sub></th><th>z<sub>abs</sub></th><th>log (N(H<sub>I</sub>))</th><th>Wavelength coverage (Å)</th></tr></thead><tbody><tr><td>QSO J0008-2900</td><td>2.219-29.012</td><td>2.645</td><td>2.254</td><td>20.22 ± 0.10</td><td>3300-4970,5730-10420</td></tr><tr><td>QSO J0008-2901</td><td>2.24-29.024</td><td>2.607</td><td>2.491</td><td>19.94 ± 0.11</td><td>3300-4970,5730-10420</td></tr><tr><td><b>QSO J0018-0913</b></td><td>4.730-9.231</td><td>0.756</td><td>0.584</td><td>20.11 ± 0.10</td><td>3065-3875,4620-5602,5675-6650</td></tr><tr><td>QSO J0041-4936</td><td>10.381-49.603</td><td>3.24</td><td>2.248</td><td>20.46 ± 0.13</td><td>3290-4520,4620-5600,5675-6650</td></tr><tr><td>QSO B0128-2150</td><td>22.773-21.58</td><td>1.9</td><td>1.857</td><td>20.21 ± 0.09</td><td>3045-3868,4785-5755,5830-6810</td></tr><tr><td><b>QSO J0132-0823</b></td><td>23.041-8.397</td><td>1.121</td><td>0.647</td><td>20.60 ± 0.12</td><td>3065-3875,4620-5602,5675-6650</td></tr><tr><td>QSO B0307-195B</td><td>47.538-19.369</td><td>2.122</td><td>1.788</td><td>19.00 ± 0.10</td><td>3065-5758,5835-8520,8660-10420</td></tr><tr><td>QSO J0427-1302</td><td>66.78-13.048</td><td>2.166</td><td>1.562</td><td>19.35 ± 0.10</td><td>3285-4515,4780-5760,5835-6810</td></tr><tr><td>PKS 0454-220</td><td>74.037-21.986</td><td>0.534</td><td>0.474</td><td>19.45 ± 0.03</td><td>3050-3870,4170-5162,5230-6210</td></tr><tr><td>J060008.1-504036</td><td>90.033-50.677</td><td>3.13</td><td>2.149</td><td>20.40 ± 0.12</td><td>3300-4520,4620-5600,5675-6650</td></tr><tr><td>QSO B1036-2257</td><td>159.79-23.224</td><td>3.13</td><td>2.533</td><td>19.30 ± 0.10</td><td>3300-5758,5838-8525,8660-10420</td></tr><tr><td>J115538.6+053050</td><td>178.911+5.514</td><td>3.475</td><td>3.327</td><td>21.00 ± 0.10</td><td>3300-5600,5675-7500,7665-9460</td></tr><tr><td>LBQS 1232+0815</td><td>188.656+7.979</td><td>2.57</td><td>1.720</td><td>19.48 ± 0.13</td><td>3285-4520,4620-5600,5675-6650</td></tr><tr><td>QSO J1330-2522</td><td>202.717-25.372</td><td>3.91</td><td>2.654</td><td>19.56 ± 0.13</td><td>3300-4515,4780-5757,5835-6810</td></tr><tr><td>QSO J1356-1101</td><td>209.195-11.025</td><td>3.006</td><td>2.397</td><td>19.85 ± 0.08</td><td>3757-4985,6700-8520,8660-10420</td></tr><tr><td>QSO J1621-0042</td><td>245.32-0.714</td><td>3.7</td><td>3.104</td><td>19.70 ± 0.20</td><td>3300-4515,4780-5757,5835-6810</td></tr><tr><td>4C 12.59</td><td>247.938+11.934</td><td>1.792</td><td>0.531</td><td>20.70 ± 0.09</td><td>3060-3870,4780-5757,5835-6810</td></tr><tr><td>LBQS 2114-4347</td><td>319.331-43.573</td><td>2.04</td><td>1.912</td><td>19.50 ± 0.10</td><td>3050-10420</td></tr><tr><td>QSO B2126-15</td><td>322.3-15.645</td><td>3.268</td><td>2.638</td><td>19.25 ± 0.15</td><td>3300-5600,5675-6650,6695-8520,</td></tr><tr><td>-</td><td>-</td><td>-</td><td>2.769</td><td>19.20 ± 0.15</td><td>8650-10420</td></tr><tr><td>LBQS 2132-4321</td><td>324.025-43.138</td><td>2.42</td><td>1.916</td><td>20.74 ± 0.09</td><td>3290-4530,4620-5600,5675-6650</td></tr><tr><td>QSO B2318-1107</td><td>350.369-10.856</td><td>2.96</td><td>1.629</td><td>20.52 ± 0.14</td><td>3050-4515,4780-5760,5840-6810</td></tr></tbody></table>

remaining of the EUADP sample (Zafar et al. 2013a), in line with standard practice at this spectral resolution (O'Meara et al. 2015).

The absorption redshifts, which are based on the N(HI) or Mg II features, are used to analyse the associated metal lines. Table 1 summarizes the properties of the quasars and absorbers in the sample studied here. The two additional objects which were not originally published by Zafar et al. (2013a) are shown in bold.

## 2.2 Literature sample

In addition to these 15 new sub-DLA measurements (+7 DLAs), we gather metallicity estimates of sub-DLAs from the remaining part of the EUADP sample as well as other recently published samples (Meiring et al. 2006, 2009; Dessauges-Zavadsky et al. 2009; Battisti et al. 2012; Som et al. 2015). In order to compare the properties of sub-DLAs to that of DLAs, we add to the sample a collection of DLA metallicity measurements from the EUADP sample as well as from the literature (see earlier references and Berg et al. 2015b). Altogether, this literature sample is the largest and most up-to-date sub-DLA sample published today.

The table in Appendix B lists the metallicity estimates of the full sample of absorbers and associated references. Fig. 1 illustrates the distribution in redshift of the absorber sample studied for both DLAs and sub-DLAs (top and middle panels, respectively). The bottom panel presents the N(HI) distribution of the sample. We stress that the additional systems are consistent with the parent sample as they are not selected on their metal content or redshift but solely on their HI column density (see also Fig. 5).

In conclusion, the final sample, referred to as the EUADP+ sample, contains 92 sub-DLAs (with 15 new measurements) and 362 DLAs (7 new measurements). Clearly, the data presented here contribute most in the sub-DLA HI column density range.

# 3 ANALYSIS

## 3.1 Method

The continua of the quasar spectra are fitted using a spline function connecting the regions of the spectrum free from absorption features as described in Zafar et al. (2013b). The Voigt profile fits are performed with the `FIT/LYMAN` package within the `MIDAS` environment (Fontana & Ballester 1995). The routine calculates a $\chi^2$ Hessian minimization and enables fits of up to 50 free parameters including the central wavelength, the column density and the Doppler parameter of each component of the fit. This allows fitting several ions simultaneously as well as several transitions of the same species, thus making maximum use of the information available from the velocity profiles. The low-ionization species (O, Fe, Si, ... ) are fitted as a separate group from the high-ionization species (C, N, S, ... ) (e.g. Wolfe, Gawiser & Prochaska 2005; Fox et al. 2007; Milutinovic et al. 2010; Crighton, Hennawi & Prochaska 2013). The intermediate-ionization species Al III are fitted either on its own, or with the low-ionization or high-ionization species, depending on the similarity in the absorption velocity profiles.

This process allows us to identify possible blends of interloping absorbers at the positions of the features under study. In case of blending, the profiles are fitted using information on central wavelengths and Doppler parameters from other un-blended profiles, thus leading to upper limits in the column density determination. In addition, saturated transitions or components are avoided because the column density information cannot be recovered in that case. The quasar continuum solution is iteratively refined when necessary during the Voigt profile fitting process. The fits are performed minimizing the number of components. In cases where a transition is not detected, we derive a $3\sigma$ upper limit from an estimate of the SNR of the spectra at the expected position of the line. The
<figure><img src="image_4.png" /><figcaption>**Figure 1.** Absorption redshifts and N(HI) distributions of the DLAs and sub-DLAs in our sample compared with the remaining absorbers covered by the EUADP survey and the literature (referred to as EUADP+ sample). The vertical line in the bottom panel indicates the canonical DLA definition. Clearly, the data presented here contribute most in the sub-DLA H1 column density range at low redshift where few systems have been studied so far.</figcaption></figure>

laboratory wavelengths and oscillator strengths used throughout the fits are taken from Morton (2003).<fnref n="1" />

We estimate the abundance for various elements of each absorbing system by summing the column densities of the different components found in the velocity profile described above. The metallicity

[X/H] of an element X with respect to solar metallicity is derived from the following expression:

$$[X/H] = \log \left( \frac{N(X)}{N(H)} \right) - \log(X/H)_{\odot} \quad (1)$$

where $(X/H)_{\odot}$ is the photospheric solar abundance from Asplund et al. (2009) and N(X) is the column density of element X. The column density of each element is taken to be that of the dominant ion, and ionization correction is ignored here (see Section 3.2 for further discussion on this point). The error estimate on the total column density log N is calculated from the error on individual column density log N of each component through the error propagation formula:

$$\sigma_{\log(N(X))} = \frac{\sqrt{\sum_i (N(X)_i \sigma_{\log(N(X)_i)})^2}}{N(X)} \quad (2)$$

The global uncertainty on the abundance determination is then calculated from a quadratic sum of $\sigma_{\log(N(X))}$ and $\sigma_{\log(N(H))}$ since the errors in the solar abundances would introduce systematic effects which can be neglected in studies of relative abundances.

The resulting Voigt profile parameters and corresponding velocity plots for the low-, intermediate- and high-ionization species as well as a detailed description of the 22 individual systems mentioned earlier are provided in Appendix C. The column densities and abundances derived for these systems are gathered in Tables 2 (for total column densities) and 3 (for abundances).

For the different H1 and metals column densities presented in this paper, the associated error on the abundances are based on $\chi^2$ minimization. The continuum placement error is not taken into account to be consistent with other measurements from the literature.

## 3.2 The ionized fraction of sub-DLAs

Given that observationally we are sensitive to the neutral gas in quasar absorbers, it is important to quantify the fraction of gas ionized in these systems. In the DLA column density range, the ionization corrections are below the typical abundance measurement errors (Vladilo et al. 2001; Dessauges-Zavadsky et al. 2003).

The situation might differ in the sub-DLA H1 column density range given that the lower N(H1) might prevent complete self-shielding from the surrounding UV background. To address this issue, Dessauges-Zavadsky et al. (2003), Meiring et al. (2007, 2009), Som et al. (2013, 2015) among others studied the ionized fraction of sub-DLAs based on photoionization CLOUDY modelling of individual systems. These studies show that the ionized fraction of hydrogen varies greatly within the sub-DLA H1 column density range (see e.g. fig. 4 of Meiring et al. 2009 and fig. 10 of Lehner et al. 2014). Nevertheless, while sub-DLAs might have an important fraction of their gas ionized in some cases, the ionization corrections to the measured abundances for sub-DLAs are often low. The large majority of elements require an ionization correction $\epsilon < 0.3$ dex, while it is negligible for FeII but important for ZnII (Dessauges-Zavadsky et al. 2003). Based on these past results and in order to be in line with abundance measurements from the literature reported here, we choose not to apply ionization correction to the new abundances presented. A more statistical approach is now required. To this end, Fumagalli et al. (submitted) have recently built CLOUDY model grids to establish posterior probability distribution functions for different states of the gas with a Bayesian formalism and Markov Chain Monte Carlo algorithm. While such an analysis is beyond the scope of the current paper, we plan to address these issues in further publications.

<footnote n="1">¹ Recently, a new set of oscillator strengths for SII and ZnII lines has been derived for studies of the interstellar medium (ISM), DLAs and sub-DLAs (Kisielius et al. 2014, 2015). A change from Morton (2003) oscillator strengths to this new study would lower [Zn/H] by about 0.1 dex.</footnote>
<table><caption>**Table 2.** Total logarithmic column densities of the newly studied systems derived from the Voigt profile fits. In column N(X), (a) refers to Ar I, (b) to O I, (c) to N I, (d) to Ti II, (e) to C I, and (f) to C II. For PKS 0454-220, the abundances with the asterisk have been derived by Som et al. (2015).</caption><thead><tr><th>QSO</th><th>z<sub>abs</sub></th><th>N(H I)</th><th>N(S II)</th><th>N(Al II)</th><th>N(Si II)</th><th>N(Cr II)</th><th>N(Mg I)</th><th>N(Mg II)</th></tr></thead><tbody><tr><td>QSO J0008-2900</td><td>2.254</td><td>20.22 ± 0.1</td><td>—</td><td>—</td><td>&lt;14.40</td><td>&lt;12.37</td><td>—</td><td>&gt;15.01</td></tr><tr><td>QSO J0008-2901</td><td>2.491</td><td>19.94 ± 0.11</td><td>13.68 ± 0.18</td><td>—</td><td>—</td><td>&lt;12.90</td><td>—</td><td>—</td></tr><tr><td><strong>QSO J0018-0913</strong></td><td>0.584</td><td>20.11 ± 0.1</td><td>—</td><td>—</td><td>—</td><td>&lt;12.97</td><td>&lt;13.04</td><td>—</td></tr><tr><td>QSO J0041-4936</td><td>2.248</td><td>20.46 ± 0.13</td><td>&lt;14.82</td><td>&gt;14.06</td><td>14.78 ± 0.03</td><td>13.12 ± 0.45</td><td>—</td><td>—</td></tr><tr><td>QSO B0128-2150</td><td>1.857</td><td>20.21 ± 0.09</td><td>14.33 ± 0.03</td><td>—</td><td>14.82 ± 0.02</td><td>—</td><td>&lt;13.21</td><td>—</td></tr><tr><td><strong>QSO J0132-0823</strong></td><td>0.647</td><td>20.60 ± 0.12</td><td>—</td><td>—</td><td>—</td><td>&lt;13.17</td><td>12.60 ± 0.04</td><td>—</td></tr><tr><td>QSO B0307-195B</td><td>1.788</td><td>19.00 ± 0.10</td><td>—</td><td>—</td><td>15.00 ± 0.01</td><td>&lt;12.77</td><td>12.54 ± 0.00</td><td>—</td></tr><tr><td>QSO J0427-1302</td><td>1.562</td><td>19.35 ± 0.10</td><td>—</td><td>11.78 ± 0.10</td><td>—</td><td>&lt;12.39</td><td>&lt;12.38</td><td>—</td></tr><tr><td>PKS 0454-220</td><td>0.474</td><td>19.45 ± 0.03</td><td>15.06 ± 0.04*</td><td>—</td><td>&gt; 14.33*</td><td>—</td><td>—</td><td>—</td></tr><tr><td>J060008.1-504036</td><td>2.149</td><td>20.40 ± 0.12</td><td>—</td><td>&gt;14.33</td><td>15.08 ± 0.01</td><td>13.10 ± 0.01</td><td>—</td><td>—</td></tr><tr><td>QSO B1036-2257</td><td>2.533</td><td>19.30 ± 0.1</td><td>—</td><td>12.52 ± 0.01</td><td>13.64 ± 0.01</td><td>&lt;12.54</td><td>—</td><td>13.57 ± 0.02</td></tr><tr><td>J115538.6+053050</td><td>3.327</td><td>21.00 ± 0.1</td><td>15.31 ± 0.01</td><td>—</td><td>15.93 ± 0.01</td><td>—</td><td>&lt;13.33</td><td>—</td></tr><tr><td>LBQS 1232+0815</td><td>1.720</td><td>19.48 ± 0.13</td><td>&lt;14.19</td><td>—</td><td>14.41 ± 0.01</td><td>&lt;12.38</td><td>&lt;12.21</td><td>—</td></tr><tr><td>QSO J1330-2522</td><td>2.654</td><td>19.56 ± 0.13</td><td>—</td><td>12.18 ± 0.02</td><td>—</td><td>—</td><td>—</td><td>—</td></tr><tr><td>QSO J1356-1101</td><td>2.397</td><td>19.85 ± 0.08</td><td>—</td><td>—</td><td>—</td><td>&lt;12.64</td><td>—</td><td>—</td></tr><tr><td>QSO J1621-0042</td><td>3.104</td><td>19.70 ± 0.2</td><td>—</td><td>—</td><td>13.78 ± 0.03</td><td>—</td><td>—</td><td>—</td></tr><tr><td>4C 12.59</td><td>0.531</td><td>20.70 ± 0.09</td><td>—</td><td>—</td><td>—</td><td>—</td><td>—</td><td>—</td></tr><tr><td>LBQS 2114-4347</td><td>1.912</td><td>19.50 ± 0.10</td><td>&lt;13.97</td><td>13.00 ± 0.01</td><td>14.39 ± 0.02</td><td>&lt;12.77</td><td>—</td><td>14.40 ± 0.01</td></tr><tr><td>QSO B2126-15</td><td>2.638</td><td>19.25 ± 0.15</td><td>—</td><td>—</td><td>14.67 ± 0.02</td><td>—</td><td>—</td><td>—</td></tr><tr><td>QSO B2126-15</td><td>2.769</td><td>19.20 ± 0.15</td><td>—</td><td>&gt;14.04</td><td>14.79 ± 0.01</td><td>&lt;12.40</td><td>—</td><td>—</td></tr><tr><td>LBQS 2132-4321</td><td>1.916</td><td>20.74 ± 0.09</td><td>&gt;14.90</td><td>—</td><td>15.55 ± 0.01</td><td>13.32 ± 0.02</td><td>—</td><td>—</td></tr><tr><td>QSO B2318-1107</td><td>1.629</td><td>20.52 ± 0.14</td><td>&lt;14.54</td><td>&lt;14.93</td><td>—</td><td>&lt;12.47</td><td>&lt;12.37</td><td>—</td></tr></tbody></table><table><thead><tr><th>QSO</th><th>N(Fe II)</th><th>N(Ni II)</th><th>N(Zn II)</th><th>N(Al III)</th><th>N(Si IV)</th><th>N(C IV)</th><th>N(Mn II)</th><th>N(X)</th></tr></thead><tbody><tr><td>QSO J0008-2900</td><td>13.78 ± 0.01</td><td>—</td><td>&lt;11.68</td><td>12.39 ± 0.04</td><td>13.72 ± 0.03</td><td>—</td><td>&lt;12.02</td><td>&lt;13.07<sup>(a)</sup></td></tr><tr><td>QSO J0008-2901</td><td>13.65 ± 0.02</td><td>&lt;13.29</td><td>&lt;12.12</td><td>&lt;12.20</td><td>—</td><td>—</td><td>—</td><td>15.31 ± 0.24<sup>(b)</sup></td></tr><tr><td><strong>QSO J0018-0913</strong></td><td>13.87 ± 0.03</td><td>—</td><td>&lt;12.41</td><td>—</td><td>—</td><td>—</td><td>—</td><td>—</td></tr><tr><td>QSO J0041-4936</td><td>14.43 ± 0.04</td><td>13.07 ± 0.07</td><td>11.70 ± 0.10</td><td>12.90 ± 0.01</td><td>—</td><td>&gt;14.56</td><td>—</td><td>14.03 ± 0.03<sup>(c)</sup></td></tr><tr><td>QSO B0128-2150</td><td>14.44 ± 0.01</td><td>13.26 ± 0.05</td><td>&lt;12.26</td><td>12.78 ± 0.01</td><td>—</td><td>—</td><td>—</td><td>—</td></tr><tr><td><strong>QSO J0132-0823</strong></td><td>14.96 ± 0.07</td><td>—</td><td>—</td><td>—</td><td>—</td><td>—</td><td>—</td><td>12.39 ± 0.11<sup>(d)</sup></td></tr><tr><td>QSO B0307-195B</td><td>14.48 ± 0.00</td><td>&lt;13.22</td><td>&lt;12.18</td><td>—</td><td>&gt;14.55</td><td>&gt;15.13</td><td>&lt;12.13</td><td>—</td></tr><tr><td>QSO J0427-1302</td><td>12.23 ± 0.04</td><td>&lt;13.23</td><td>&lt;11.75</td><td>—</td><td>13.90 ± 0.07</td><td>—</td><td>&lt;11.84</td><td>—</td></tr><tr><td>PKS 0454-220</td><td>14.71 ± 0.01</td><td>13.69 ± 0.08*</td><td>—</td><td>—</td><td>—</td><td>—</td><td>12.58 ± 0.01</td><td>—</td></tr><tr><td>J060008.1-504036</td><td>14.84 ± 0.03</td><td>13.62 ± 0.02</td><td>12.11 ± 0.03</td><td>12.78 ± 0.01</td><td>—</td><td>—</td><td>—</td><td>&lt;12.5<sup>(e)</sup></td></tr><tr><td>QSO B1036-2257</td><td>12.93 ± 0.01</td><td>&lt;12.93</td><td>&lt;11.74</td><td>—</td><td>13.71 ± 0.01</td><td>&gt;17.42</td><td>—</td><td>—</td></tr><tr><td>J115538.6+053050</td><td>—</td><td>13.74 ± 0.01</td><td>—</td><td>13.12 ± 0.01</td><td>13.56 ± 0.01</td><td>13.71 ± 0.01</td><td>—</td><td>—</td></tr><tr><td>LBQS 1232+0815</td><td>13.50 ± 0.01</td><td>&lt;13.05</td><td>&lt;11.58</td><td>13.28 ± 0.01</td><td>&gt;14.67</td><td>—</td><td>—</td><td>—</td></tr><tr><td>QSO J1330-2522</td><td>—</td><td>&lt;13.22</td><td>—</td><td>12.62 ± 0.02</td><td>—</td><td>—</td><td>—</td><td>—</td></tr><tr><td>QSO J1356-1101</td><td>13.44 ± 0.01</td><td>&lt;12.76</td><td>&lt;12.38</td><td>—</td><td>—</td><td>—</td><td>&lt;12.07</td><td>—</td></tr><tr><td>QSO J1621-0042</td><td>13.30 ± 0.04</td><td>—</td><td>—</td><td>—</td><td>14.24 ± 0.03</td><td>14.71 ± 0.01</td><td>—</td><td>&lt;14.41<sup>(f)</sup></td></tr><tr><td>4C 12.59</td><td>14.26 ± 0.08</td><td>—</td><td>—</td><td>—</td><td>—</td><td>—</td><td>—</td><td>—</td></tr><tr><td>LBQS 2114-4347</td><td>14.02 ± 0.01</td><td>&lt;12.88</td><td>&lt;12.17</td><td>&lt;12.09</td><td>13.43 ± 0.01</td><td>14.39 ± 0.01</td><td>&lt;12.24</td><td>—</td></tr><tr><td>QSO B2126-15</td><td>14.05 ± 0.01</td><td>13.15 ± 0.01</td><td>&lt;11.58</td><td>13.24 ± 0.02</td><td>—</td><td>—</td><td>—</td><td>—</td></tr><tr><td>QSO B2126-15</td><td>14.17 ± 0.00</td><td>—</td><td>&lt;11.95</td><td>13.11 ± 0.01</td><td>13.84 ± 0.13</td><td>—</td><td>&lt;12.28</td><td>—</td></tr><tr><td>LBQS 2132-4321</td><td>15.03 ± 0.02</td><td>13.77 ± 0.02</td><td>12.66 ± 0.02</td><td>13.25 ± 0.01</td><td>14.20 ± 0.01</td><td>—</td><td>—</td><td>—</td></tr><tr><td>QSO B2318-1107</td><td>14.14 ± 0.02</td><td>—</td><td>&lt;11.74</td><td>12.17 ± 0.02</td><td>—</td><td>&lt;14.10</td><td>11.78 ± 0.04</td><td>—</td></tr></tbody></table>

### 3.3 Assessing the dust content of quasar absorbers: a multi-element analysis

Refractory elements are easily incorporated on to dust (e.g. Fe, Cr, Ni), while volatile elements are less prone to locking up into dust grains (e.g. Zn, S). To estimate the level of depletion of a given line of sight, it is possible to compare the abundance of a volatile element with that of a refractive element. The quantity [Zn/Fe] is therefore an excellent tool to probe the quantity of Fe atoms locked into dust (Vladilo 1998). Indeed, Zn is thought to behave like Fe in different stages of chemical evolution, excluding the effects of dust depletion. From studies of low metallicity stars in our Galaxy, (Saito et al. 2009; Barbuy et al. 2015), [Zn/Fe] stays steady at [Zn/Fe] ~ 0 down to metallicities [Fe/H] = -3 and then

increases for lower values of [Fe/H]. Hence, [Zn/H] provides a robust metallicity indicator. Unfortunately, its low cosmic abundance and long rest-frame wavelengths make it challenging to measure in sub-DLAs, preventing from a robust dust-metallicity derivation.

Here, we propose a different approach for the study of dust depletion based on the multi-element analysis proposed by Jenkins (2009) to assess the level of dust in a given line of sight. Jenkins (2009) proposed to use the abundances of different elements (namely C, N, O, Mg, Si, P, Cl, Ti, Cr, Mn, Fe, Ni, Cu, Zn, Ge, Kr and S) to compare the dust depletion of dense neutral hydrogen systems to that of the interstellar medium (ISM) of our Galaxy. Using a sample of 243 sight lines in our Galaxy, he established a connection between the line-of-sight depletion factor F*
<table><caption>**Table 3.** Abundances with respect to solar for the 22 systems studied in this work. In column [X/H], (a) refers to Ar, (b) refers to O, (c) refers to N and (d) refers to C. For PKS 0454-220, the metallicities with the asterisk have been derived by Som et al. (2015).</caption><thead><tr><th>QSO</th><th>z<sub>abs</sub></th><th>log N(H<sub>I</sub>)</th><th>[S/H]</th><th>[Al/H]</th><th>[Si/H]</th><th>[Cr/H]</th></tr></thead><tbody><tr><td>QSO J0008-2900</td><td>2.254</td><td>20.22 ± 0.10</td><td>—</td><td>—</td><td>&lt; -1.33</td><td>&lt; -1.49</td></tr><tr><td>QSO J0008-2901</td><td>2.491</td><td>19.94 ± 0.11</td><td>-1.38 ± 0.21</td><td>—</td><td>—</td><td>&lt; -0.68</td></tr><tr><td><b>QSO J0018-0913</b></td><td>0.584</td><td>20.11 ± 0.10</td><td>—</td><td>—</td><td>—</td><td>&lt; -0.78</td></tr><tr><td>QSO J0041-4936</td><td>2.248</td><td>20.46 ± 0.13</td><td>&lt; -0.75</td><td>&gt; -0.85</td><td>-1.19 ± 0.16</td><td>-0.98 ± 0.58</td></tr><tr><td>QSO B0128-2150</td><td>1.857</td><td>20.21 ± 0.09</td><td>-1.00 ± 0.09</td><td>—</td><td>-0.90 ± 0.09</td><td>—</td></tr><tr><td><b>QSO J0132-0823</b></td><td>0.647</td><td>20.60 ± 0.12</td><td>—</td><td>—</td><td>—</td><td>&lt; -1.07</td></tr><tr><td>QSO B0307-195B</td><td>1.788</td><td>19.00 ± 0.10</td><td>—</td><td>—</td><td>0.49 ± 0.10</td><td>&lt; 0.13</td></tr><tr><td>QSO J0427-1302</td><td>1.562</td><td>19.35 ± 0.10</td><td>—</td><td>-2.02 ± 0.14</td><td>—</td><td>&lt; -0.60</td></tr><tr><td>PKS 0454-220</td><td>0.474</td><td>19.45 ± 0.03</td><td>0.49 ± 0.04*</td><td>—</td><td>&gt; -0.78*</td><td>—</td></tr><tr><td>J060008.1-504036</td><td>2.149</td><td>20.40 ± 0.12</td><td>—</td><td>&gt; -0.52</td><td>-0.83 ± 0.12</td><td>-0.94 ± 0.12</td></tr><tr><td>QSO B1036-2257</td><td>2.533</td><td>19.30 ± 0.10</td><td>—</td><td>-1.24 ± 0.10</td><td>-1.17 ± 0.10</td><td>&lt; -0.40</td></tr><tr><td>J115538.6+053050</td><td>3.327</td><td>21.00 ± 0.10</td><td>-0.81 ± 0.10</td><td>—</td><td>-0.58 ± 0.10</td><td>—</td></tr><tr><td>LBQS 1232+0815</td><td>1.720</td><td>19.48 ± 0.13</td><td>&lt; -0.41</td><td>—</td><td>-0.58 ± 0.13</td><td>&lt; -0.74</td></tr><tr><td>QSO J1330-2522</td><td>2.654</td><td>19.56 ± 0.13</td><td>—</td><td>-1.83 ± 0.13</td><td>—</td><td>—</td></tr><tr><td>QSO J1356-1101</td><td>2.397</td><td>19.85 ± 0.08</td><td>—</td><td>—</td><td>—</td><td>&lt; -0.85</td></tr><tr><td>QSO J1621-0042</td><td>3.104</td><td>19.70 ± 0.20</td><td>—</td><td>—</td><td>-1.43 ± 0.20</td><td>—</td></tr><tr><td>4C 12.59</td><td>0.531</td><td>20.70 ± 0.09</td><td>—</td><td>—</td><td>—</td><td>—</td></tr><tr><td>LBQS 2114-4347</td><td>1.912</td><td>19.50 ± 0.10</td><td>&lt; -0.65</td><td>-0.95 ± 0.10</td><td>-0.62 ± 0.10</td><td>&lt; -0.37</td></tr><tr><td>QSO B2126-15</td><td>2.638</td><td>19.25 ± 0.15</td><td>—</td><td>—</td><td>-0.09 ± 0.15</td><td>—</td></tr><tr><td>QSO B2126-15</td><td>2.769</td><td>19.20 ± 0.15</td><td>—</td><td>&gt; 0.39</td><td>0.08 ± 0.15</td><td>&lt; -0.44</td></tr><tr><td>LBQS 2132-4321</td><td>1.916</td><td>20.74 ± 0.09</td><td>&gt; -0.96</td><td>—</td><td>-0.70 ± 0.10</td><td>-1.06 ± 0.11</td></tr><tr><td>QSO B2318-1107</td><td>1.629</td><td>20.52 ± 0.14</td><td>&lt; -1.10</td><td>&lt; -0.04</td><td>—</td><td>&lt; -1.69</td></tr><tr><th>QSO</th><th>[Fe/H]</th><th>[Ni/H]</th><th>[Zn/H]</th><th>[Mg/H]</th><th>[Mn/H]</th><th>[X/H]</th></tr><tr><td>QSO J0008-2900</td><td>-1.94 ± 0.10</td><td>—</td><td>&lt; -1.10</td><td>&gt; -0.81</td><td>&lt; -1.63</td><td>&lt; -1.55<sup>(a)</sup></td></tr><tr><td>QSO J0008-2901</td><td>-1.79 ± 0.13</td><td>&lt; -0.87</td><td>&lt; -0.38</td><td>—</td><td>—</td><td>-1.32 ± 0.35<sup>(b)</sup></td></tr><tr><td><b>QSO J0018-0913</b></td><td>-1.74 ± 0.10</td><td>—</td><td>&lt; -0.26</td><td>—</td><td>—</td><td>—</td></tr><tr><td>QSO J0041-4936</td><td>-1.54 ± 0.14</td><td>-1.61 ± 0.20</td><td>-1.32 ± 0.16</td><td>—</td><td>—</td><td>-2.36 ± 0.13<sup>(c)</sup></td></tr><tr><td>QSO B0128-2150</td><td>-1.27 ± 0.09</td><td>-1.17 ± 0.10</td><td>&lt; -0.51</td><td>—</td><td>—</td><td>—</td></tr><tr><td>J013209-082349</td><td>-1.14 ± 0.14</td><td>—</td><td>—</td><td>—</td><td>—</td><td>—</td></tr><tr><td>QSO B0307-195B</td><td>-0.02 ± 0.10</td><td>&lt; 0.00</td><td>&lt; 0.62</td><td>—</td><td>&lt; -0.30</td><td>—</td></tr><tr><td>QSO J0427-1302</td><td>-2.62 ± 0.11</td><td>&lt; -0.34</td><td>&lt; -0.16</td><td>—</td><td>&lt; -0.94</td><td>—</td></tr><tr><td>PKS 0454-220</td><td>-0.24 ± 0.03</td><td>0.02 ± 0.09*</td><td>—</td><td>—</td><td>-0.30 ± 0.03</td><td>-1.34 ± 0.09<sup>(c)</sup></td></tr><tr><td><b>QSO J0132-0823</b></td><td>-1.06 ± 0.12</td><td>-1.00 ± 0.12</td><td>-0.85 ± 0.12</td><td>—</td><td>—</td><td>—</td></tr><tr><td>QSO B1036-2257</td><td>-1.87 ± 0.10</td><td>&lt; -0.59</td><td>&lt; -0.12</td><td>-1.33 ± 0.10</td><td>—</td><td>—</td></tr><tr><td>J115538.6+053050</td><td>—</td><td>-1.48 ± 0.10</td><td>—</td><td>—</td><td>—</td><td>—</td></tr><tr><td>LBQS 1232+0815</td><td>-1.48 ± 0.13</td><td>&lt; -0.65</td><td>&lt; -0.46</td><td>—</td><td>—</td><td>—</td></tr><tr><td>QSO J1330-2522</td><td>—</td><td>&lt; -0.56</td><td>—</td><td>—</td><td>—</td><td>—</td></tr><tr><td>QSO J1356-1101</td><td>-1.91 ± 0.08</td><td>&lt; -1.31</td><td>&lt; -0.03</td><td>—</td><td>&lt; -1.21</td><td>—</td></tr><tr><td>QSO J1621-0042</td><td>-1.90 ± 0.20</td><td>—</td><td>—</td><td>—</td><td>—</td><td>&lt; -1.72<sup>(d)</sup></td></tr><tr><td>4C 12.59</td><td>-1.94 ± 0.12</td><td>—</td><td>—</td><td>—</td><td>—</td><td>-5.77<sup>(d)</sup></td></tr><tr><td>LBQS 2114-4347</td><td>-0.98 ± 0.10</td><td>&lt; -0.84</td><td>&lt; 0.11</td><td>-0.70 ± 0.10</td><td>&lt; -0.69</td><td>—</td></tr><tr><td>QSO B2126-15</td><td>-0.70 ± 0.15</td><td>-0.32 ± 0.15</td><td>&lt; -0.23</td><td>—</td><td>—</td><td>—</td></tr><tr><td>QSO B2126-15</td><td>-0.53 ± 0.15</td><td>—</td><td>&lt; 0.19</td><td>—</td><td>&lt; -0.35</td><td>—</td></tr><tr><td>LBQS 2132-4321</td><td>-1.21 ± 0.11</td><td>-1.19 ± 0.11</td><td>-0.64 ± 0.11</td><td>—</td><td>—</td><td>—</td></tr><tr><td>QSO B2318-1107</td><td>-1.88 ± 0.14</td><td>—</td><td>&lt; -1.34</td><td>—</td><td>-2.17 ± 0.15</td><td>—</td></tr></tbody></table>

and the different elements' abundances of each sight line. We refer the reader to Appendix A1 for a mathematical description of the method.

Fig. 2 shows the fit for the line of sight depletion factor $F_*$ (slope) for both populations of quasar absorbers from the EUADP+ sample. For each element, we plot in cyan the median of the detections if there is at least four systems measured. The vertical error bars represent the error on the median using a bootstrap technique with a confidence level of 95 per cent.

We are confronted with a large number of non-detections, creating a bias in the sample towards metal-rich systems. A large fraction of these upper (resp. lower) limits falls below (resp. above) the associated median. To address this issue, a survival analysis is considered. A Buckley-James linear regression, from the stddas.statistics

package in IRAF, results in $F_* = -0.34 \pm 0.19$ for sub-DLAs and $F_* = -0.70 \pm 0.06$ for DLAs.

On the one hand, both populations show negative values for $F_*$, suggesting that sub-DLAs and DLAs arise in galaxies with a lower dust content than the Milky Way. On the other hand, the derived $F_*$ values for both populations are different at the $1.8\sigma$ level. The sub-DLA population is consistent with the Halo like ISM from our Galaxy<fnref n="2" /> while the DLAs are described by an $F_*$ value well below the ones measured in the Milky Way. This is counter intuitive as we expect DLAs to be self-shielded from the UV background towards

<footnote n="2">² $F_* = -0.28$ for Halo like ISM, $F_* = -0.08$ for Disc+Halo like ISM, $F_* = 0.12$ for Warm Disc like ISM and $F_* = 0.90$ for Cool Disc like ISM</footnote>
<figure><img src="image_5.png" /><figcaption>**Figure 2.** Fits of $F_*$ from equation (A5) for the DLAs (362 systems, left-hand panel), and sub-DLAs (92 systems, right-hand panel) in the EUADP+ sample. The blue crosses stand for the detections, the red triangles for the upper limits, the green triangles for lower limits, and the cyan points are the median of the detections for each element X. The fits are performed on the medians of the detections with a bisector fit (dashed line), and on the detections and the limits using a survival analysis technique, the Buckley–James method (solid line). We note that the $\alpha$-elements (Mg and Si) are below the trend lines for both DLAs and sub-DLAs. We refer the reader to Appendix A1 for a mathematical description of the fit.</figcaption></figure>

the centre of the galaxy. Indeed, numerous cosmological simulations predict DLAs to be closer to the centre of the galaxy than sub-DLAs (Fumagalli et al. 2011; Faucher-Giguere et al. 2015). They should therefore exhibit an $F_*$ value corresponding to regions within the halo.

But DLAs and sub-DLAs might not be systematically associated with spiral galaxies. They might arise from a mixture of galaxy types, hence the non-physical values of $F_*$. In addition, the method described here is based on measurements in our Galaxy at log $N(H_1) > 19.5$ to limit photoionization effects, while our quasar absorber sample goes down to log $N(H_1) = 19.0$. Furthermore, the ionization levels of the sub-DLAs and DLAs in our EUADP+ sample are higher than in the Milky Way ISM, as $F_*$ is quite different between ionized and neutral gas ($F_* = -0.1$ for the warm ionized medium and $F_* = 0.1$ for the warm neutral medium, e.g. Draine 2011). We derive $F_*$ for log $N(H_1) > 19.5$ sub-DLAs, and find similar results, suggesting that ionization effects do not affect the results much. Moreover, the quasar absorbers trace gas at high redshifts, which may differ from the Milky Way properties as a local galaxy. Overall, these results suggest that quasar absorbers differ from the Galactic depletion patterns or alternatively have a different nucleosynthetic history.

Also, the current QSO sample may suffer from dust selection bias. Indeed, it is possible that quasars in the background of dusty absorbers are not being accounted for in current selection techniques (Boissé et al. 1998). Programs to observe reddened quasars might bring valuable insights to the dust content of quasar absorbers (Maddox et al. 2012; Krogåger et al. 2015, 2016). Using the analysis from Vladilo et al. (2006),<fnref n="3" /> we recover estimates for the average extinction in our quasar absorber samples to be below 0.01, in line

with results from Frank & Péroux (2010) or Khare et al. (2012). This suggests that the dust reddening is not observed in the current quasar selection.

Given these limitations, we do not apply dust corrections to the measured abundances. There is work underway (Tchernyshyov et al. 2015) to derive the parameters $A_X$, $B_X$ and $z_X$ for the Small Magellanic Cloud, which is more in line with the expected morphological type or $H_2$ fraction of DLAs.

### 3.4 $\alpha$-elements

The production of $\alpha$-elements (O, N, Mg, Si, S, Ti, Ca, ...) and Fe-peak elements (V, Cr, Mn, Fe, Co, Ni, ...) has different origins in the history of star formation. $\alpha$-elements are mainly created during core-collapse Type II supernovae (SNe), whereas Fe-peak elements originate mainly from thermonuclear Type Ia SNe. These two processes have different time-scales, as they originate from distinct stellar populations: the Type II SNe occur from short-lived massive stars while Type Ia SNe are thought to involve binary pairs containing a white dwarf exchanging material over longer periods of time. Observations of different objects suggest an excess of $\alpha$-elements with respect to Fe-peak elements (from Wallerstein (1962) for G-dwarf stars, to Timmes, Lauroesch & Truran (1995) for QSO absorption line systems and Rafelski et al. (2012) for DLAs).

In Fig. 3, we plot [$\alpha$/Fe] versus metallicity using $\alpha = O_1$, S II, Mg II and Si II for the sub-DLA (blue) and DLA (red) populations.

We observe a correlation between [$\alpha$/Fe] and [$\alpha$/H] for sub-DLAs. A Spearman test gives $\rho_{sub-DLA} = 0.69$ with a probability of no correlation $P(\rho_{sub-DLA}) < 10^{-7}$. This correlation spans from low- to high-metallicity systems. The total number of DLA detections adds up to 227 systems. We do not see a flattening for DLAs with [$\alpha$/H] < -1 as in Rafelski et al. (2012), who attributed this flattening to the fact that the offsets in [$\alpha$/Fe] values for [$\alpha$/H] < -1

<footnote n="3">³ see Appendix A2 for details of the calculation</footnote>
<figure><img src="image_6.png" /><figcaption>**Figure 3.** The α-enhancement of DLAs (red) and sub-DLAs (blue) versus metallicity, [α/Fe] versus [α/H], with α = O I, S II or Si II. For clarity, only one in 10 data point displays error bars and the limits have faint colours.</figcaption></figure>

are the effect of α-enhancement only. To avoid any dust extinction effects, we consider the 80 DLAs with [α/H] < −1.5 to derive a correction for α-enhancement for the EUADP+ DLAs (De Cia et al. 2013). We note that these systems might still be affected by dust depletion, as a trend is still visible between [α/Fe] and [α/H], even for [α/H] down to −3 dex. We derive a mean value of [α/Fe] = 0.32 ± 0.18 using 80 DLAs with [α/H] < −1.5, which is consistent with the value found by Rafelski et al. (2012).

DLAs and sub-DLAs may have different nucleosynthetic histo-
ries, as they may originate from galaxies of different masses (Khare
et al. 2007; Kulkarni et al. 2010) and hence experience different
star formation rates. Indeed, different [Mn/Fe] versus [Zn/H] trends
for DLAs and sub-DLAs suggest different nucleosynthetic histo-
ries for the two populations (Meiring et al. 2007; Som et al. 2015).
Therefore, one expects their α-enhancement to be statistically dif-
ferent and probably higher for sub-DLAs, which may experience
higher star formation rates. In Fig. 3, there is no apparent plateau for
sub-DLAs, probably due to the small number of detections at low
metallicities. More observations of sub-DLAs are needed to obtain
more definitive conclusions in this H I column density regime. Nev-
ertheless, to address the question of α-enhancement for sub-DLAs
at least partly, we make use of the value derived for DLAs. These
corrections add 0.32 ± 0.18 dex to every metallicity derived using
element Fe. This does not include a correction for dust extinction.

We emphasize that such a trend of [α/Fe] versus [α/H] in DLAs/sub-DLAs does not necessarily imply nucleosynthetic α-enhancement. This is because of the increasing dust depletion of Fe with increasing metallicity, a trend that is seen to hold even at metallicities below −1 dex. [α/Zn] is indeed less prone to depletion than [α/Fe], but our current sub-DLA sample has only a limited number of Zn detections (19/92). Additional Zn observations in the future will help address this question better.

4 RESULTS

4.1 Evolution of metals with redshift

Together, DLA and sub-DLA populations contain the majority of the
neutral gas mass in the Universe (Zafar et al. 2013b). Therefore, they
present a valuable tool to estimate the cosmic metallicity through-
out the ages. Models of cosmic chemical evolution claim that the

global interstellar metallicity would rise with decreasing redshift, to
reach near solar metallicity values at present day (Lanzetta, Wolfe
& Turnshek 1995; Pei & Fall 1995; Malaney & Chaboyer 1996; Pei,
Fall & Hauser 1999; Tissera, Mosconi & Cora 2001). Sub-DLAs in
particular contribute substantially to the cosmic metal budget. In-
deed, Kulkarni et al. (2007) show that the contribution of sub-DLAs
to the metal budget increases with decreasing redshift considering
a constant relative H I gas in DLAs and sub-DLAs at low and high
redshifts. Bouché et al. (2007) anticipate that ≲ 17 per cent of the
metals are in sub-DLAs at z ∼ 2.5 but this estimate is highly de-
pendent on the ionized fraction of the gas. It is therefore highly
important to compare sub-DLA metallicities with those of DLAs.
Our study adds 15 new measurements of sub-DLA metallicity. We
chose to use Zn II as our main metallicity indicator (Pettini et al.
1994) as it is nearly undepleted on to interstellar dust. Moreover,
Zn II lines are usually unsaturated, and since Zn II is the dominant
ionization state in neutral regions, it does not require strong ioniza-
tion correction. However, Zn has an overall low cosmic abundance
and the stronger lines λλ 2026 and 2062 can be blended with Mg I λ
2026 and Cr II λ 2062. When these Zn II lines are undetected, we use
the dominant ions of other elements in the following order: O I, S II,
Si II, Mg II, Fe III (corrected for the α analysis) and Ni II.

Fig. 4 shows the evolution of the metallicity [M/H] with redshift of the systems for the 92 sub-DLAs (bottom panel) and the 362 DLAs (top panel) from the EUADP+ sample, colour-coded with respect to the element used to derive the metallicity. We note that Zn is only detected up to z = 3 (but for one DLA measured at z ∼ 4), and O is only derived for metal-poor systems ([M/H] < −1) because OI λ 1302, the only O I line usually accessible to ground-based telescopes, is saturated otherwise.

Lanzetta et al. (1995) estimated the cosmic metallicity from the
gas mass density Ω_g and metal mass density Ω_m via the H I-weighted
mean metallicity 〈Z〉:

$$
\langle Z(z) \rangle = \Omega_m(z) / \Omega_g(z) = \frac{\sum_i Z_i N(H_i)_i}{\sum_i N(H_i)_i} \quad (3)
$$

Fig. 5 shows the metallicity derived in our sample, as well as the H I-weighted mean metallicity 〈Z〉 for both populations (sub-DLAs in blue and DLAs in red). The bins for 〈Z〉 are chosen such that there is an almost constant number of systems in each bin, that is 16 for the sub-DLAs and 26 for the DLAs. The vertical error bars are derived from the consideration on sampling and measurements errors. The sampling errors are calculated from a bootstrap technique as described in Rafelski et al. (2012) and the measurement errors from the propagation formula. The total errors are the quadratic sums of these two quantities for each bin. We note a large scatter for a third of the newly derived sub-DLA metallicities (blue dots). This points out to the need for a larger sample of sub-DLA measurements at all redshifts.

We measure an anti-correlation between redshift and metallicity for both populations. The Spearman coefficient for sub-DLAs is ρ = −0.49 and ρ = −0.55 for DLAs, with probabilities of no correlation P(ρ) < 10⁻⁶ for both populations. The Kendall’s τ is −0.34 for sub-DLAs and −0.38 for DLAs, with a probability of no-correlation of below 10⁻⁵ for both populations. The dotted lines in Fig. 5 show the best bisector fits for the metallicity evolution with redshift of both populations. We measure

$$
\langle Z \rangle_{\text{DLAs}} = (-0.15 \pm 0.03) z - (0.6 \pm 0.13) \quad (4)
$$

$$
\langle Z \rangle_{\text{sub-DLAs}} = (-0.30 \pm 0.07) z + (0.15 \pm 0.31) \quad (5)
$$
<figure><img src="image_7.png" /></figure>

<figure><img src="image_8.png" /><figcaption>**Figure 4.** Evolution of [M/H] with redshift, colour-coded with respect to the element used to derive the metallicity for DLAs (top panel) and sub-DLAs (bottom panel) from the EUADP+ sample.</figcaption></figure>

The fit has been performed shifting the y-axis to z = 3 to minimize the error on the intercept and ignoring the last DLA bin which presents a rapid decline in metallicity (Rafelski et al. 2014). The evolution with redshift is steeper for sub-DLAs than for DLAs. Previous authors (Khare et al. 2007; Kulkarni et al. 2010) argued that this effect might arise from the fact that sub-DLAs are more massive than DLAs.

Our results are in agreement with previous work (Kulkarni et al. 2007, 2010; Som et al. 2015), with a more significant result in the sub-DLA regime thanks to the larger sample presented here. The slope remains unchanged with respect to earlier studies. However, the significance of the result increases indicating a convergence towards a realistic value of the slope.

<figure><img src="image_9.png" /><figcaption>**Figure 5.** Evolution of the N(H I)-weighted mean metallicity 〈Z〉 with redshift. Clearly, both DLA and sub-DLA populations show an increase of 〈Z〉 with decreasing redshift, but sub-DLAs have a steeper evolution of 〈Z〉 with redshift than DLAs. We also note a floor at [X/H] = -3 below which no metals are detected.</figcaption></figure>

## 4.2 Kinematics

In addition to the different abundances derived from Voigt profile fitting, information on the kinematics of the absorbers can be derived from the UVES high-resolution spectra.

### 4.2.1 Voigt profile optical depth method

We use the definition of the velocity interval $\Delta V_{90}$ as defined by Prochaska & Wolfe (1997b), based on the integrated optical depth $\tau_{tot} = \int \tau(v)dv$ and considering the velocity interval from 5 per cent to 95 per cent of this quantity.

In this paper, we do not consider the apparent optical depth (AOD) $\tau_{app} = -\log(I/I_c)$ to derive the velocity interval, as is usually done, but we use instead the optical depth derived from the Voigt profile fits (see Appendix C for a description of the fits for every system individually). This method, which we refer to as Voigt profile optical depth (VPOD) method, makes use of the information gathered from the fits. The saturation and contamination issues are then considered when deriving $\Delta V_{90}$. This is the main difference with the AOD method, which might provide $\Delta V_{90}$ measurements affected by blends. In the VPOD method, we use simultaneously the information on several transitions to derive the velocity interval for any ion. Indeed, the only quantity that differs between transitions of the same ion is the oscillator strength, which has no impact on the velocity axis. Fig. 6 shows an example of the derivation of the velocity interval for an Fe II line. Table 4 summarizes the $\Delta V_{90}$ measurements for the 22 systems studied here. For 20 of them, we use the information from the Fe II lines as it is the ion most detected in our sample.

One of the sub-DLA in our sample, towards PKS 0454-220, has already been studied by Som et al. (2015). They use $\mathrm{SII}\ \lambda\ 1250$ from an HST/COS spectrum and derive $\Delta V_{90} = 155\ \mathrm{km}\ \mathrm{s}^{-1}$ based on the AOD method. However, we find with the VPOD method described above a value almost twice smaller. We use the AOD method on the UVES spectrum with $\mathrm{FeII}\ \lambda\ 2374$ and derive $\Delta V_{90} \sim 85.0\ \mathrm{km}\ \mathrm{s}^{-1}$,
<figure><img src="image_10.png" /><figcaption>**Figure 6.** An example illustrating the computation of the velocity interval $\Delta V_{90}$. The black curve is the normalized spectrum of PKS 0454-220 centred on the Fe II λ 2374 line, the red curve is the Voigt profile fit of the absorption and the blue curve is the integrated optical depth derived from the Voigt profile. The vertical dotted lines indicate the 5 per cent and 95 per cent thresholds for the integrated optical depth, defining the velocity width $\Delta V_{90}$.</figcaption></figure>

<table><caption>**Table 4.** Measures of $\Delta V_{90}$ in our sample derived from Voigt profile fits to the Fe II lines (except for two systems with no Fe coverage, for which we used Si II (a) and Al II (b)).</caption><thead><tr><th>QSO</th><th>z<sub>abs</sub></th><th>log N(H i) [cm<sup>-2</sup>]</th><th>Δv<sub>90</sub> [km s<sup>-1</sup>]</th></tr></thead><tbody><tr><td>QSO J0008-2900</td><td>2.254</td><td>20.22</td><td>53.7</td></tr><tr><td>QSO J0008-2901</td><td>2.491</td><td>19.94</td><td>12.4</td></tr><tr><td>QSO J0018-0913</td><td>0.584</td><td>20.11</td><td>192.6</td></tr><tr><td>QSO J0041-4936</td><td>2.248</td><td>20.46</td><td>21.2</td></tr><tr><td>QSO B0128-2150</td><td>1.857</td><td>20.21</td><td>53.7</td></tr><tr><td><b>QSO J0132-0823</b></td><td>0.647</td><td>20.60</td><td>76.5</td></tr><tr><td>QSO B0307-195B</td><td>1.788</td><td>19.00</td><td>204.8</td></tr><tr><td>QSO J0427-1302</td><td>1.562</td><td>19.35</td><td>7.8</td></tr><tr><td>PKS 0454-220</td><td>0.474</td><td>19.45</td><td>78.7</td></tr><tr><td>J060008.1-504036</td><td>2.149</td><td>20.40</td><td>79.9</td></tr><tr><td>QSO B1036-2257</td><td>2.533</td><td>19.30</td><td>220.4</td></tr><tr><td>J115538.6+053050</td><td>3.327</td><td>21.00</td><td>186.8<sup>a</sup></td></tr><tr><td>LBQS 1232+0815</td><td>1.72</td><td>19.48</td><td>167.6</td></tr><tr><td>QSO J1330-2522</td><td>2.654</td><td>19.56</td><td>21.0<sup>b</sup></td></tr><tr><td>QSO J1356-1101</td><td>2.397</td><td>19.85</td><td>337.7</td></tr><tr><td>QSO J1621-0042</td><td>3.104</td><td>19.70</td><td>161.9</td></tr><tr><td>4C 12.59</td><td>0.531</td><td>20.70</td><td>62.4</td></tr><tr><td>LBQS 2114-4347</td><td>1.912</td><td>19.50</td><td>135.9</td></tr><tr><td>QSO B2126-15</td><td>2.638</td><td>19.25</td><td>62.3</td></tr><tr><td>QSO B2126-15</td><td>2.769</td><td>19.20</td><td>121.2</td></tr><tr><td>LBQS 2132-4321</td><td>1.916</td><td>20.74</td><td>233.4</td></tr><tr><td>QSO B2318-1107</td><td>1.629</td><td>20.52</td><td>13.8</td></tr></tbody></table>

consistent with the result from the VPOD method. We note that the Line Spread Function (LSF) derived from the COS consortium is responsible for the reported large value. To overcome this problem, we exclude COS measurements from our analysis.

In conclusion, the VPOD $\Delta V_{90}$ values are not sensitive to blending and saturation effects, to the shape of the instrument's LSF, its resolution and to the SNR of the derived spectrum. We note that depletion of refractory elements contributes to the error in the $\Delta V_{90}$ because the different components can be affected differently by dust depletion. In the present study, Fe II has been used because it is uniformly detected among the 22 new systems presented here. In the remaining of the sample there is no object in common between the EUADP and the already derived $\Delta V_{90}$ found in the literature.

### 4.2.2 $\Delta V_{90}$ versus metallicity relation

Recently, Som et al. (2015) compared for the first time the sub-DLA metallicity versus velocity width trend over a statistically significant sample of 31 sub-DLAs at $0.1 \le z_{abs} \le 3.1$. We propose here to extend their analysis to a wider sub-DLA sample using our new 15 sub-DLAs. We consider a different sample than the one used in the remaining of the paper (EUADP+) as the velocity widths are not provided by all authors. We consider the data from Ledoux et al. (2006) (52 DLAs and 14 sub-DLAs at redshifts $1.7 \le z_{abs} \le 4.3$, corrected for Asplund et al. (2009) photospheric solar abundances), observations from Meiring et al. (2009) (29 sub-DLAs at redshifts $z_{abs} > 1.5$, corrected for Asplund et al. (2009) photospheric solar abundances), observations from Neeleman et al. (2013) (98 DLAs at redshifts $1.6613 \le z_{abs} \le 5.0647$), observations from Moller et al. (2013) (4 DLAs at redshifts $1.9 \le z_{abs} \le 3.1$), as well as results from this study (see Table 4). We only consider the systems with detected [α/H] (11/15 sub-DLAs and 4/7 DLAs). The resulting sample gathers 54 sub-DLAs and 162 DLAs.

Fig. 7 shows the trend between the metallicity and the velocity width $\Delta V_{90}$ for sub-DLAs (bottom panel) and DLAs (top panel) from this $\Delta V_{90}$ sample.

We fit both populations with the best bisector fits:

$$[X/H]_{\text{DLA}} = (1.52 \pm 0.08) \log \Delta V_{90} - (4.20 \pm 0.16) \quad (6)$$

$$[X/H]_{\text{sub-DLA}} = (1.61 \pm 0.22) \log \Delta V_{90} - (3.94 \pm 0.45) \quad (7)$$

The fits are performed shifting the y-axis to $\log \Delta V_{90} = 2$ to minimize the error on the intercept.

Som et al. (2015) find a higher intercept and a shallower slope for the sub-DLA population, using only Zn and S with ionization corrections. Although this result is free from dust depletion effect on the metallicity estimation, it might be biased towards higher metallicity sub-DLAs, where Zn or S can be measured. A larger Zn-based metallicity sub-DLAs samples is required to recover the metallicity-$\Delta V_{90}$ relation free from the effects of dust bias.

A larger Zn-based metallicity sub-DLAs samples is required to recover the metallicity-Delta v relation free from the effects of dust bias.

As in previous studies, the DLA sample is well correlated. The Spearman coefficient is $\rho = 0.63$, with a probability of no correlation $<10^{-6}$. The Kendall's $\tau$ is 0.46 with a probability of no correlation $<10^{-6}$. The sub-DLA sample is less correlated than the DLA sample, in agreement with Som et al. (2015). The Spearman coefficient is $\rho = 0.39$, with a probability of no correlation of 0.004. The Kendall's $\tau$ is 0.25 with a probability of no correlation of 0.007. Adding more sub-DLAs to the $\Delta V_{90}$-metallicity relation does not improve the correlation. Som et al. (2015) showed that the ionization correction also does not improve this correlation. This indicates a larger spread for the sub-DLAs, which may originate from more complex kinematic behaviours in sub-DLA clouds. However, the determination of $\Delta V_{90}$ appears to be sensitive to the resolution, the LSF and the SNR of the data. This might contribute to the observed scatter, although an intrinsic scatter is expected from CGM regions.

### 4.2.3 Is $\Delta V_{90}$ a reliable tracer of mass?

A mass-metallicity relation (hereafter MZR) has been reported at low redshifts (Lequeux et al. 1979; Tremonti et al. 2004), intermediate redshifts (Savaglio et al. 2005) and high redshifts (Erb et al. 2006). It relates the stellar mass of galaxies to the metallicity of
<figure><img src="image_11.png" /><figcaption>**Figure 7.** [X/H] versus $\Delta V_{90}$ for the newly derived systems, the systems from Ledoux et al. (2006), Neeleman et al. (2013), Som et al. (2015), Meiring et al. (2009), and Moller et al. (2013) in blue, red, green, cyan, magenta and yellow, respectively. The upper panel shows the DLAs and the bottom panel the sub-DLAs. The data points measured with COS (stars) are not considered for the fit due to the discussion in Section 4.2.1. The open triangles represent the sub-DLAs and the dots the DLAs. The dashed blue line reproduces the bisector fit of the sub-DLAs, the dashed red line is the bisector fit for all the DLAs and the green dashed line in the lower panel represents the Som et al. (2015) sub-DLA fit.</figcaption></figure>

their ISM. This relation is crucial in our understanding of galaxy evolution as it supports the theory of metal ejection from galactic outflows in low-mass (and hence low potential well) galaxies and their enrichment with accreting metal-poor IGM gas, diluting the galactic metallicity.

For quasar absorbers, some simulations indicate that the origin of the velocity width, $\Delta V_{90}$, could be strongly related to the gravitational potential well of the absorption system's host galaxy (e.g. Prochaska & Wolfe 1997b; Haehnelt, Steinmetz & Rauch 1998; Pontzen et al. 2008). Similarly, assuming a scaling of the galaxies luminosity with dark matter haloes, Ledoux et al. (2006) and later

Moller et al. (2013) proposed to interpret the $\Delta V_{90}$ versus metallicity relation of quasar absorbers as an MZR. Such a picture does not take into account the complex gas processes at play now known to take place in CGM regions. In other words, the $\Delta V_{90}$ may reflect bulk motions of the absorbing gas rather than motions governed by the gravitational potential well.

Observationally, a measurement of mass and $\Delta V_{90}$ has been possible in few individual systems. Infra-red IFU SINFONI observations of the galaxy hosts of three DLAs and two sub-DLAs in Péroux et al. (2011) and Péroux, Kulkarni & York (2014) allow one to determine the mass of the systems from a detailed kinematic study. In addition, Christensen et al. (2014) has used photometric information of the galaxy hosts and spectral energy distribution (SED) fits to estimate the stellar mass of 13 DLAs. Combined together, these findings suggest that, individually, the absorption systems align well with the MZR reported at these redshifts.

In addition to these measurements in a few specific systems, several authors have put constraints on the mass estimates of quasar absorbers in a statistical manner. Interestingly, the local analogues to DLAs, the 21cm $z=0$ emitting galaxies studied with HIPASS by Zwaan et al. (2008) show that the quantity $\Delta V_{90}$ correlates little with mass. Similarly, Bouché et al. (2007) (and later Lundgren et al. 2009; Gauthier et al. 2014) have used the ratio of Mg II systems autocorrelation with a correlation with luminous red galaxies (LRG) at the same redshifts to derive an estimate of the overall mass of quasar absorbers. Their findings show an anti-correlation between equivalent width, a proxy for $\Delta V_{90}$, and metallicity. Admittedly, the populations of absorbers do not completely overlap, the Ledoux et al. (2006) sample contains mostly DLAs, while the Mg II sample of Bouché et al. (2007) might have at most 25 per cent of DLAs (according to the criterion of Rao et al. (2006): 50 per cent meet the Fe II/Mg II criteria and 35–50 per cent of these are DLAs). In fact, Bouché et al. (2007) and Schroetter et al. (2015) argue that Mg II absorbers can be used to trace superwinds as they are not virialized in the gaseous halo of the host galaxies. Bouché et al. (2012) also show that the inclination of the galaxy has a direct impact on the absorption profile and therefore on the velocity width. Put together, these many lines of evidence question the interpretation of the velocity width as a proxy for the mass of the host galaxy and the interpretation of the $\Delta V_{90}$/metallicity correlation as an MZR for quasar absorbers.

## 4.3 Tracing the CGM with sub-DLAs

Our understanding of galaxy formation and evolution is tightly linked with the study of two opposite processes that take place within the CGM. Indeed, to create stars, the galaxy requires a continuous input of cold gas, that is believed to accrete along the filamentary structures from the cosmic web. In addition, cosmological simulations fail to reproduce the observed SFR without invoking feedback processes from star formation itself or AGN activity. These outflowing processes and their large scale impact have been confirmed observationally (Steidel et al. 2010; Bouché et al. 2012; Kacprzak et al. 2014), but there is still little observational evidence for accretion of cool material (Bouché et al. 2013; Cantalupo et al. 2014; Martin et al. 2014). Quasar absorbers with H I column densities in the range of LLS and sub-DLAs are believed to be good probes of this CGM (Fumagalli et al. 2011; van de Voort & Schaye 2012). Lehner et al. (2013, 2014) report a bimodality in the metallicity distribution of $29 < z < 1$ LLS, which they interpret as the signatures of outflows (metal-rich) and infalls (metal-poor).
Lehner et al. (2013) extended their analysis on 29 sub-DLAs and 26 DLAs, but do not report a bimodality distribution in the metallicity of these systems based on α-elements. Clearly, larger samples of quasar absorbers are required to perform such studies.

Here, we perform similar analysis on a larger sample of sub-DLAs and DLAs with a broad redshift range.

Fig. 8 shows the bimodal metallicity distribution in $z < 1$ LLS by Lehner et al. (2013) and the α-element metallicity distribution for DLAs (316 systems) and sub-DLAs (68 systems) derived from our EUADP+ sample at all redshifts. The sub-DLA [$\alpha$/H] distribution in the middle panel of Fig. 8 also suggests bimodality.

In Fig. 9, we plot the distribution of the α abundances (left-hand panels) and Fe abundances (right-hand panels) for the EUADP+ sub-DLAs in three redshift bins ($z_{abs} > 2.4$ for the upper panels, $1.25 \le z_{abs} \le 2.4$ for the middle panels and $z_{abs} < 1.25$ for the bottom panels). We consider the metallicity traced by Fe II as we have more detections with this ion and it is little affected by photoionization effect, even though Fe has an inclination to lock up on to dust grains. These histograms reveal the strong metallicity evolution with redshift for sub-DLAs. The sub-DLAs in the high redshift bin, $z_{abs} > 2.4$, present an unimodal distribution centred around [M/H]~−1.6, similar to the metal-poor LLS population derived by Lehner et al. (2013). At intermediate redshifts, $1.25 \le z_{abs} \le 2.4$, a transition from low to higher metallicities appears. At low redshifts, $z_{abs} < 1.25$, however, the distribution presents hints of a bimodal distribution. This trend is more pronounced for the [Fe/H] distribution. A DIP test rejects the unimodal distribution at a significance level of 83 per cent, taking the upper limit as a detection. The peaks of the distribution are located at [Fe/H] = −1.12 and [Fe/H] = −0.29, from a Gaussian Mixture Modelling. These values are compared with what is expected from simulations in terms of metallicity of accreting or outflowing gas. The prediction for the cold-mode accretion metallicity is above a hundredth solar, which is in line with the metal poor population in our distribution (Ocvirk et al. 2008; Shen et al. 2013). Therefore, the metal rich population should trace either outflowing gas or gas directly associated with the galaxy’s ISM. However, this is not seen in the [$\alpha$/H] distribution, where the DIP test rejects the unimodal distribution at a significance level of 31 per cent, still taking upper limits as detections. But these limits are located at the high metallicity end of the distribution, and therefore do not contradict the possible bimodal distribution seen in [Fe/H].

These results indicate a similar behaviour for low redshift sub-DLAs as for low redshift LLS. However, we expect the position of the peaks to be higher than those derived for the $z < 1$ LLS, as the [Fe/H] metallicity is underestimated due to depletion of Fe on to dust grains. Lehner et al. (in prep.) show that the bimodal distribution for LLS disappears at higher redshifts, similarly to what we find with sub-DLAs at higher redshifts. We note however that the bimodality in LLS could perhaps be incorrect, given that there are larger uncertainties in the metallicity determination of LLS (due to ionization corrections).

We note that the effect of redshift plays an essential role in such an analysis, as illustrated in Fig. 9.

Altogether, larger samples of both LLS and sub-DLAs at low-redshifts are required to distinguish between metal-poor gas accreting on to the galaxy and metal-rich gas being expelled.

## 5 CONCLUSION

We present in this paper physical properties of 15 new sub-damped Lyman α absorbers seen in absorption in background quasar’s

<figure><img src="image_12.png" /></figure>

<figure><img src="image_13.png" /></figure>

<figure><img src="image_14.png" /><figcaption>**Figure 8.** Metallicity [$\alpha$/H] distribution of LLSs (top panel), sub-DLAs (middle panel) and DLAs (bottom panel). The histogram for LLSs has been taken from Lehner et al. (2013) and indicates a bimodality in the metallicity distribution for LLS at $z < 1$. The black vertical dashed lines represent the mean values derived from the $z_{abs} < 1$ LLS sub-groups by Lehner et al. (2013).</figcaption></figure>
<figure><img src="image_15.png" /><figcaption>**Figure 9.** Metallicity (left-hand panels: [α/H], right-hand panels: [Fe/H]) distribution of sub-DLAs for different redshift bins: $z > 2.4$ (top panels), $1.25 < z < 2.4$ (middle panels) and $z < 1.25$ (bottom panels). The black vertical dashed lines represent the mean values derived from the $z_{abs} < 1$ LLS sub-groups by Lehner et al. (2013). The black areas represent upper limits. The metallicity distribution is a strong function of redshift and only the lowest redshift range presents hints of a bimodal distribution for the [Fe/H] metallicity.</figcaption></figure>
high-resolution UVES spectra. These systems cover a wide redshift range ($0.584 \le z_{\text{abs}} \le 3.104$). The metallicity measurements were performed using Voigt profile fitting of the normalized high resolution UVES quasar spectra. Our sub-DLA measurements add significantly to previous studies since high-resolution spectroscopy is required to study these systems.

We apply a multi-element based method to assess the level of dust depletion in the line of sight to the quasar. This study appears to be promising as it uses the combined information from several ions, and is relative to measurements of our Galaxy's ISM. With a survival analysis, we derive the best fit of the depletion factor $F_*$ for the DLAs and sub-DLAs and find negative values, statistically different, for both groups: $F_{*}^{\text{sub-DLA}} = -0.34 \pm 0.19$ and $F_{*}^{\text{DLA}} = -0.70 \pm 0.06$. In comparison with values derived in our Galaxy, DLAs lie outside the halo and the sub-DLAs are associated with Halo like stars, in terms of depletion patterns. This is counter-intuitive as we expect DLAs to be more self-shielded to the UV background than sub-DLAs. We conclude that quasar absorbers differ from the Galactic depletion patterns or alternatively have a different nucleosynthetic history. Future analysis with the Small Magellanic Cloud will enable comparisons to a galaxy more in line with the morphology or the $H_2$ fraction of DLAs. Moreover, we derive the averaged rest frame extinction $A_V$ for both populations to be below 0.01, suggesting that dust reddening is not observed in the current quasar selection.

We then examine the relative abundances of Fe and $\alpha$-elements. We derived an offset in [$\alpha$/Fe] for the DLAs in our sample of $0.32 \pm 0.18$, excluding systems with [$\alpha$/H] > -1.5 to be less sensitive to dust depletion. This value is similar to that derived by Rafelski et al. (2012). However, we cannot derive a similar parameter for the sub-DLA population as we can not disentangle dust depletion effects from the $\alpha$-enhancement. We therefore apply the DLA corrections to the sub-DLAs.

We study the evolution of the cosmic metallicity $\Omega_m$, also described by the mean $H_1$-weighted metallicity ($Z$). We confirm the steeper evolution of sub-DLAs than DLAs eventually reaching a solar metallicity at low redshifts as expected from chemical evolution models. We note that a third of the newly derived sub-DLA abundances appear as outliers from the previous data.

We measure the velocity width of the absorption systems in our new sample, $\Delta V_{90}$, with a new method using the information from the Voigt profile fits. We confirm that there is a correlation between $\Delta V_{90}$ and metallicity for sub-DLAs. Indeed, sub-DLAs are potentially probing a different mass range than DLAs. Sub-DLAs could have a more important feedback mechanism than DLAs, thus increasing the scatter and weakening the possible velocity width/metallicity correlation.

Finally, we look at the metallicity distribution of sub-DLAs. At low redshifts, $z_{\text{abs}} < 1.25$, we see a hint of a bimodal distribution which peaks at $\sim -1.1$ and $\sim -0.3$. This indicates that low-redshift sub-DLAs are tracing different mechanisms at play within the CGM, such as cold-mode accretion and outflows. Larger samples of sub-DLAs and LLS abundances at low redshifts are required to better identify their connection to gas inflow/outflow processes.

## ACKNOWLEDGEMENTS

This study includes observations collected during programme ESO 91.A-0300 at the European Southern Observatory (ESO) Very Large Telescope (VLT) with UVES on the 8.2 m telescopes operated at the Paranal Observatory, Chile. We thank N. Lehner, C. Howk, M. Fumagalli, M. Rafelski, M. Pieri, R. Bordoloi, J. O'Meara, D. Som and P. Møller for useful discussions. This work has been funded within

the BINGO! ('history of Baryons: Intergalactic medium/Galaxies cO-evolution') project by the Agence Nationale de la Recherche (ANR) under the allocation ANR-08-BLAN-0316-01 as well as within the REGAL ('what REgulates the growth of GALaxies?') project by the Labex (Laboratoire d'Excellence) OCEVU ('Origines, Constituants et Evolution de l'Univers'). This work has been carried out thanks to the support of the OCEVU Labex (ANR-11-LABX-0060) and the A*MIDEX project (ANR-11-IDEX-0001-02) funded by the 'Investissements d'Avenir' French government program managed by the ANR. We thanks Pierre Mege for contributing in the development of the VPOD method. SQ acknowledges CNRS and CNES support for the funding of his PhD. CP thanks the ESO science visitor program for support. VPK acknowledges partial support from the NSF grant AST/1108830, with additional support from NASA grant NNX14AG74G and NASA/STScI grant for program GO 12536. EJ thanks Aix-Marseille University and Cécile Gry for a visit where part of this work was undertaken.

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## SUPPORTING INFORMATION

Additional Supporting Information may be found in the online version of this article:

**Table B1.** Partial list of damped and sub-damped absorbers identified in the EUADP+, with the column densities of Zn II, Fe II and S II, as well as estimates of their metallicity based on the ion specified (http://www.mnras.oxfordjournals.org/lookup/suppl/doi:10.1093/mnras/stw524/-/DC1).

Please note: Oxford University Press is not responsible for the content or functionality of any supporting materials supplied by the authors. Any queries (other than missing material) should be directed to the corresponding author for the article.

## APPENDIX A: MULTI-ELEMENT ANALYSIS

### A1 Derivation of F*

Jenkins (2009) proposed to use the abundances of different elements (namely C, N, O, Mg, Si, P, Cl, Ti, Cr, Mn, Fe, Ni, Cu, Zn, Ge, Kr and S) to compare the dust depletion of dense neutral hydrogen systems to that of the ISM of our Galaxy. Specifically, the depletion [X<sub>gas</sub>/H] described in Jenkins (2009) is the difference between the observed abundance of element X normalized to the total hydrogen abundance in both neutral and molecular phases, N(H) = N(H<sub>1</sub>) + 2N(H<sub>2</sub>), and its intrinsic abundance (assumed to be solar, initially):

$$[X_{\text{gas}}/\text{H}] = \log(\text{X/H})_{\text{obs}} - \log(\text{X/H})_{\odot} \quad (\text{A1})$$

Using 243 sight lines in our Galaxy, Jenkins (2009) linearly fits the following formula:

$$[X_{\text{gas}}/\text{H}]_{\text{fit}} = [X_{\text{gas}}/\text{H}]_{0} + A_{X}F_{*} \quad (\text{A2})$$

where F* is defined as the line-of-sight depletion factor,<fnref n="4" /> A<sub>X</sub> as the propensity of the element X to increase the absolute value of its particular depletion level as F* becomes larger and [X<sub>gas</sub>/H]<sub>0</sub> as the depletion for element X when F* = 0. This equation can linearly be rewritten as

$$[X_{\text{gas}}/\text{H}]_{\text{fit}} = B_{X} + A_{X}(F_{*} - z_{X}) \quad (\text{A3})$$

where F* has its zero-point reference displaced to an intermediate value z<sub>X</sub> (unique to element X), B<sub>X</sub> being the depletion at F* = z<sub>X</sub>. The three parameters, A<sub>X</sub>, B<sub>X</sub> and z<sub>X</sub>, are then solved for each element (table 4 of Jenkins 2009).

In the case of DLAs and sub-DLAs,<fnref n="5" /> releasing the hypothesis of solar metallicity, equation (A1) can be rewritten as follows:

$$[X_{\text{gas}}/\text{H}] = \log(\text{X/H})_{\text{obs}} - \log(\text{X/H})_{\text{intrinsic}} \quad (\text{A4})$$

where log(X/H)<sub>intrinsic</sub> is the abundance of element X in the absence of depletion. Equation (A3) then becomes:

$$[X/H]_{\text{obs}} - B_{X} + A_{X}z_{X} = [X/H]_{\text{intrinsic}} + A_{X}F_{*} \quad (\text{A5})$$

where [X/H]<sub>obs</sub> is the metallicity compared to solar as we measure it (hence affected by depletion) and [X/H]<sub>intrinsic</sub> is the intrinsic metallicity compared to solar of the system derived from element X (corrected for depletion). We derive F* by linearly fitting the left hand side of equation (A5) as a function of A<sub>X</sub>, thus providing an estimate of the intrinsic metallicity.

### A2 Derivation of A<sub>V</sub>

Our study relates to the rest frame extinction A<sub>V</sub> through equation 3 of Vladilo et al. (2006), which scales A<sub>V</sub> to the dust-phase column density of iron N̄<sub>Fe</sub>. Assuming that zinc is completely undepleted, and that the intrinsic ratio Zn/Fe ratio in DLAs and sub-DLAs is solar, we can express N̄<sub>Fe</sub> as the following:

$$\widehat{N}_{\text{Fe}} = f_{\text{Fe}}N_{\text{Zn}} \left( \frac{\text{Fe}}{\text{Zn}} \right)_{\odot} \quad (\text{A6})$$

where f<sub>Fe</sub> = 1 - 10<sup>δFe</sup> is the fraction of iron in dust form. We can assume δFe = [Fe/Zn]<sub>obs</sub>. To recover N<sub>Zn</sub>, we use the assumption that [Zn/H] = [X/H], with [X/H] being the metallicity derived for each system using the ion X (when Zn is not detected). We obtain the following expression:

$$\log \widehat{N}_{\text{Fe}} = \log (1 - 10^{[\text{Fe/Zn}]_{\text{obs}}}) + \log(N_{\text{X}}) - \log \left( \frac{N_{\text{X}}}{\widehat{N}_{\text{Fe}}} \right)_{\odot} \quad (\text{A7})$$

where N<sub>X</sub> is the column density of the ion used for the metallicity derivation for a given system.

We can use equation A5 to derive an estimate of the quantity [Fe/Zn]<sub>J</sub> from the Jenkins analysis:

$$[\text{Fe/Zn}]_{J} = (-1.01 \pm 0.07) + (-0.68 \pm 0.08)F_{*} \quad (\text{A8})$$

This results in 〈[Fe/Zn]〉<sub>J, sub-DLA</sub> = -0.78 ± 0.15 and 〈[Fe/Zn]〉<sub>J, DLA</sub> = -0.53 ± 0.10. Using a bootstrap method, we derive 〈log N̄<sub>Fe</sub>〉<sub>sub-DLA</sub> = 14.38 ± 0.80 and 〈log N̄<sub>Fe</sub>〉<sub>DLA</sub> = 14.73 ± 0.85. Based on fig. 4 from Vladilo et al. (2006), we can estimate the rest frame extinction log A<sub>V</sub> from log N̄<sub>Fe</sub>. For both populations, the value of 〈log N̄<sub>Fe</sub>〉 falls below the range of MW data used to derive the correlation, giving low values of 〈log A<sub>V</sub>〉 ≲ -2 mag. This suggests that the dust reddening is not observed in the current quasar selection.

## APPENDIX B: SAMPLE

This appendix presents the list of the first 10 damped and sub-damped absorbers identified in the EUADP+. We compile estimates of abundances from various references in the literature, as specified in the last column. We list the column density of Zn II, Fe II and S II, as well as estimates of their metallicity based on the ion specified.

<footnote n="4">⁴ We stress that this definition is based on calibration of F* against the descriptive summary definitions reported in the review article by Savage & Sembach (1996).</footnote>

<footnote n="5">⁵ We note that the measured molecular hydrogen fraction for DLAs is rather low and that this fraction is not correlated with the H<sub>I</sub> column density (Ledoux, Petitjean & Srianand 2003; Noterdaeme et al. 2008a). Therefore, the definition N(H) = N(H<sub>1</sub>) + 2N(H<sub>2</sub>) still holds for this study.</footnote>
<table><caption>**Table B1.** Partial list of damped and sub-damped absorbers identified in the EUADP+, with the column densities of Zn II, Fe II and S II, as well as estimates of their metallicity based on the ion specified. The full table (with all absorbers and ions) is available online.</caption><thead><tr><th>QSO name</th><th>z<sub>abs</sub></th><th>log N(HI)</th><th>log N(Zn)</th><th>log N(Fe)</th><th>log N(S)</th><th>[X/H]</th><th>X</th><th>Ref</th></tr></thead><tbody><tr><td>CTQ418</td><td>2.5100</td><td>20.50 ± 0.07</td><td>–</td><td>14.07 ± 0.03</td><td>13.99 ± 0.06</td><td>-1.63 ± 0.09</td><td>S II</td><td>43</td></tr><tr><td>CTQ418</td><td>2.4300</td><td>20.68 ± 0.07</td><td>–</td><td>13.91 ± 0.05</td><td>13.97 ± 0.03</td><td>-1.83 ± 0.08</td><td>S II</td><td>43</td></tr><tr><td>QXO0001</td><td>3.0000</td><td>20.70 ± 0.05</td><td>–</td><td>&lt;15.09</td><td>–</td><td>-1.62 ± 0.05</td><td>O II</td><td>92</td></tr><tr><td>Q0000-262</td><td>3.3900</td><td>21.41 ± 0.08</td><td>12.01 ± 0.05</td><td>14.87 ± 0.03</td><td>–</td><td>-1.96 ± 0.09</td><td>Zn II</td><td>62, 90</td></tr><tr><td>QSO J0003-2323</td><td>2.1870</td><td>19.60 ± 0.40</td><td>&lt;11.04</td><td>13.22 ± 0.12</td><td>&lt;13.12</td><td>-1.76 ± 0.42</td><td>O II</td><td>103</td></tr><tr><td>Q0005+0524</td><td>0.8514</td><td>19.08 ± 0.04</td><td>&lt;11.24</td><td>13.79 ± 0.01</td><td>–</td><td>-0.47 ± 0.18</td><td>Fe II</td><td>60</td></tr><tr><td>PSS0007+2417</td><td>3.5000</td><td>21.10 ± 0.10</td><td>&lt;12.39</td><td>&gt;14.63</td><td>–</td><td>-1.53 ± 0.11</td><td>Si II</td><td>94</td></tr><tr><td>PSS0007+2417</td><td>3.8400</td><td>20.85 ± 0.15</td><td>–</td><td>13.91 ± 0.03</td><td>–</td><td>-2.12 ± 0.24</td><td>Fe II</td><td>94</td></tr><tr><td>J0007+0041</td><td>4.7300</td><td>20.65 ± 0.20</td><td>–</td><td>–</td><td>–</td><td>-2.19 ± 0.20</td><td>Si II</td><td>99</td></tr><tr><td>QSO J0008-2900</td><td>2.2540</td><td>20.22 ± 0.10</td><td>&lt;11.68</td><td>13.78 ± 0.01</td><td>–</td><td>-1.33 ± 0.14</td><td>Si II</td><td>114</td></tr><tr><td>...</td><td>...</td><td>...</td><td>...</td><td>...</td><td>...</td><td>...</td><td>...</td><td>...</td></tr></tbody></table>

**References:** 1: Akerman et al. (2005), 2: Battisti et al. (2012), 3: Berg et al. (2013), 4: Berg et al. (2015a), 5: Berg et al. (2015b), 6: Bergeron & Dodorico (1986), 7: Blades et al. (1982), 8: Boissé et al. (1998), 9: Bowen et al. (2005), 10: Carswell et al. (1996), 11: Centurion et al. (2000), 12: Centurion et al. (2003), 13: Chen, Kennicutt & Rauch (2005), 14: Churchill et al. (2000), 15: Cooke et al. (2010), 16: Cooke et al. (2011b), 17: Cooke et al. (2011a), 18: Cooke, Pettini & Murphy (2012), 19: Dessauge-Zavadsky (unpublished), 20: Dessauges-Zavadsky et al. (2001), 21: Dessauges-Zavadsky, Prochaska & D'Odorico (2002), 22: Dessauges-Zavadsky et al. (2003), 23: Dessauges-Zavadsky et al. (2004), 24: Dessauges-Zavadsky et al. (2006), 25: Dessauges-Zavadsky et al. (2007), 26: Dessauges-Zavadsky, Ellison & Murphy (2009), 27: D'Odorico & Molaro (2004), 28: Dutta et al. (2014), 29: Ellison et al. (2001), 30: Ellison & Lopez (2001), 31: Ellison et al. (2007), 32: Ellison et al. (2008), 33: Ellison & Lopez (2009), 34: Ellison et al. (2010), 35: Ellison et al. (2012), 36: Fox et al. (2007), 37: Fox et al. (2009), 38: Fynbo et al. (2011), 39: Fynbo et al. (2013), 40: Ge, Bechtold & Kulkarni (2001), 41: Guimarães et al. (2012), 42: Heinmueller et al. (2006), 43: Henry & Prochaska (2007), 44: Herbert-Fort et al. (2006), 45: Kanekar et al. (2014), 46: Krogager et al. (2013), 47: Kulkarni et al. (2005), 48: Kulkarni et al. (2012), 49: Ledoux, Srianand & Petitjean (2002a), 50: Ledoux, Bergeron & Petitjean (2002b), 51: Ledoux et al. (2003), 52: Ledoux et al. (2006), 53: Lopez et al. (1999), 54: Lopez et al. (2002), 55: Lopez & Ellison (2003), 56: Lopez et al. (2005), 57: Lu et al. (1996), 58: Meiring et al. (2006), 59: Meiring et al. (2007), 60: Meiring et al. (2009), 61: Meyer, Lanzetta & Wolfe (1995), 62: Molaro et al. (2000), 63: Nestor et al. (2008), 64: Noterdaeme et al. (2007b), 65: Noterdaeme et al. (2007a), 66: Noterdaeme et al. (2008b), 67: Noterdaeme et al. (2008a), 68: Noterdaeme et al. (2012b), 69: Noterdaeme et al. (2012a), 70: Penprase et al. (2010), 71: Peroux et al. (2002), 72: Péroux et al. (2006b), 73: Péroux et al. (2007), 74: Péroux et al. (2008), 75: Petitjean, Srianand & Ledoux (2000), 76: Petitjean, Srianand & Ledoux (2002), 77: Petitjean, Ledoux & Srianand (2008), 78: Pettini et al. (1994), 79: Pettini et al. (1997a), 80: Pettini et al. (1997b), 81: Pettini et al. (1999), 82: Pettini et al. (2000), 83: Pettini et al. (2002), 84: Pettini et al. (2008b), 85: Pettini et al. (2008a), 86: Pettini & Cooke (2012), 87: Prochaska & Wolfe (1996), 88: Prochaska & Wolfe (1997a), 89: Prochaska & Wolfe (1999), 90: Prochaska & Wolfe (2002), 91: Prochaska, Gawiser & Wolfe (2001), 92: Prochaska et al. (2002), 93: Prochaska et al. (2003a), 94: Prochaska, Castro & Djorgovski (2003b), 95: Prochaska et al. (2007), 96: Prochter et al. (2010), 97: Quast, Reimers & Baade (2008), 98: Rafelski et al. (2012), 99: Rafelski et al. (2014), 100: Rao & Turnshek (2000), 101: Rao et al. (2005), 102: Rao et al. (2006), 103: Richter, Westmeier & Bruens (2005), 104: Rix et al. (2007), 105: Som et al. (2015), 106: Songaila & Cowie (2002), 107: Srianand & Petitjean (1998), 108: Srianand, Petitjean & Ledoux (2000), 109: Srianand & Petitjean (2001), 110: Srianand et al. (2005), 111: Srianand, Gupta & Petitjean (2007), 112: Srianand et al. (2012), 113: Steidel et al. (1997), 114: this work, 115: Tripp et al. (2005), 116: Turnshek et al. (2004), 117: Vladilo et al. (2011), 118: Zafar et al. (2011), 119: Zafar et al. (2014b), 120: Zafar et al. (2014a), 121: Zafar et al. (in preparation), 122: Zych et al. (2009), 123: de la Varga et al. (2000).

The online version of this table includes a more complete list of ions and the complete list of absorbers.

## APPENDIX C: INDIVIDUAL OBJECTS

This appendix summarizes a description of the individual systems as well as figures and tables providing the Voigt profile parameters for the low, intermediate and high-ionization species when available. For the following figures, we use $z_{abs}$ from the literature as the zero velocity component.

$$ \text{C1 QSOJ0008-2900 } z_{\text{em}} = 2.645, z_{\text{abs}} = 2.254, \log N(\text{HI}) = 20.22 \pm 0.10 $$

The EUADP spectrum for this absorber covers multiple low-ionization transitions including FeII λλλλλ 2374, 2382, 2586, 2600, Si II λ 1526, and the saturated Mg II doublet λλ 2796, 2803. The velocity profiles are well fitted with five components. The fit to the Fe lines is found to be consistent with the non-detection of Fe II λ 2260. The resulting total column density of Fe is $log N(Fe II) = 13.78 \pm 0.01$. By comparing the detected Si II λ 1526 line with the weak Si II λ 1808 transition, we deduce that the former is slightly

contaminated. An estimation on the column density based on Si II λ 1808 gives $log N(Si II) = 14.40 \pm 0.1$. This total column density is confirmed with the apparent optical depth method applied on Si II λ 1808 from $v = -72 \text{ km s}^{-1}$ and $v = +10 \text{ km s}^{-1}$. Because it is saturated, the Mg II doublet is fitted fixing the number of components and parameters to the low-ionization lines. The result provides a lower limit to the Mg column density of $log N(Mg II) > 15.1$. The non-detection of Cr II λ 2062, Zn II λ 2026 and Mn II λ 2576 leads to the determination of the following upper limits: $log N(Cr II) < 12.37, log N(Zn II) < 11.68$ and $log N(Mn II) < 12.02$.

In addition to these low-ionization ions, the quasar spectrum covers high-ionization species including the Si IV doublet λλλ 1393 and 1402. However, the bluest Si IV line lies on the Ly α emission line of the quasar thus complicating the quasar continuum placement. Therefore the reddest component of the Si IV doublet is used to model the Voigt profile. In addition, the intermediate-ionization lines of Al III λλ 1854 and 1862 present a similar velocity profile to the Si IV doublet. Therefore, the fit is performed using these transitions simultaneously. A satisfactory three-component fit leads to the following column densities: $log N(Si IV) = 13.72 \pm 0.03$ and $log N(Al III) = 12.39 \pm 0.04$.

The parameter fits are summarized in Table C1 and Voigt profile fits are shown in Fig. C1.
<table><caption>**Table C1.** Voigt profile fit parameters to the low- and high-ionization species for the $z_{abs} = 2.645 \log N(HI) = 20.22 \pm 0.10$ absorber towards QSO J0008-2900. In this table and in the following ones, the values with no uncertainties have been manually fixed to improve the fitting process.</caption><thead><tr><th>Comp.</th><th>z<sub>abs</sub></th><th>b<br>km s<sup>-1</sup></th><th>Ion</th><th>log N<br>cm<sup>-2</sup></th></tr></thead><tbody><tr><td>1</td><td>2.253 37</td><td>4.5 ± 0.2</td><td>Fe II<br>Si II</td><td>12.95 ± 0.01<br>13.70</td></tr><tr><td>2</td><td>2.253 52</td><td>2.8 ± 0.2</td><td>Fe II<br>Si II</td><td>13.00 ± 0.01<br>13.80</td></tr><tr><td>3</td><td>2.253 67</td><td>4.0 ± 0.2</td><td>Fe II<br>Si II</td><td>13.24 ± 0.01<br>13.85</td></tr><tr><td>4</td><td>2.253 80</td><td>5.0 ± 0.3</td><td>Fe II<br>Si II</td><td>13.20 ± 0.02<br>13.40</td></tr><tr><td>5</td><td>2.253 92</td><td>5.3 ± 0.3</td><td>Fe II<br>Si II</td><td>12.91 ± 0.02<br>13.60</td></tr><tr><td>1</td><td>2.253 32</td><td>16.1 ± 2.7</td><td>Si IV<br>Al III</td><td>13.19 ± 0.05<br>11.74 ± 0.10</td></tr><tr><td>2</td><td>2.253 66</td><td>9.0 ± 1.1</td><td>Si IV<br>Al III</td><td>13.42 ± 0.05<br>12.07 ± 0.06</td></tr><tr><td>3</td><td>2.253 89</td><td>9.2 ± 1.9</td><td>Si IV<br>Al III</td><td>13.05 ± 0.08<br>11.88 ± 0.08</td></tr></tbody></table>

$$ \begin{aligned} \text{C2 QSOJ0008-2901} & z_{\text{em}} = 2.607, z_{\text{abs}} = 2.491, \\ \log N(\text{HI}) = 19.94 \pm 0.11 \end{aligned} $$

In this case, the quasar spectrum is of modest SNR. The wavelength coverage includes low-ionization lines of Fe II λλλλλ 2260, 2344, 2382, 2586, S II λ 1259 and O I λ 1039. A two-component fit is used given the asymmetrical shape of the Fe II and S II lines. The resulting column densities are log N(Fe II)=13.65 ± 0.02, log N(O I)=15.31 ± 0.24 and log N(S II)=13.68 ± 0.18. Finally, we used the non-detection of the following transitions to derive upper limits on the column densities: Cr II λ 2062 log N(Cr II)<12.9, Ni II λ 1741 log N(Ni II)<13.29, Zn II λ 2026 log N(Zn II)<12.12 and Al III λ 1854 log N(Al II)<12.2.

The EUADP quasar spectrum does not cover the C IV doublet for this absorber. In addition, the high-ionization Si IV doublet λλλ 1393 and 1402 is covered but no satisfactory fit could be determined given the low SNR of the quasar spectrum in this region.

The resulting parameter fits are summarized in Table C2 and Voigt profile fits are shown in Fig. C2.

<figure><img src="image_16.png" /><figcaption>**Figure C1.** Fit to the low-ionization transitions of the $z_{abs} = 2.254$, log N(HI) = 20.22 ± 0.10 absorber towards QSOJ0008-2900 (see Table C1). In this and the following figures, the Voigt profile fits are overlaid in red above the observed quasar spectrum (black) and the green horizontal line indicates the normalized flux level to one. The zero velocity corresponds to the absorption redshift listed in Table 1 and the vertical dotted lines correspond to the redshift of the fitted components. We warn the reader that the y-axis varies from one panel to another in order to optimise for each transitions so that weaker lines can be readily seen.</figcaption></figure>
<table><caption>**Table C2.** Voigt profile fit parameters to the low-ionization species for the $z_{abs} = 2.491 \log N(Hi) = 19.94 \pm 0.11$ absorber towards QSO J0008-2901.</caption><thead><tr><th>Comp.</th><th>z<sub>abs</sub></th><th>b<br>km s<sup>-1</sup></th><th>Ion</th><th>log N<br>cm<sup>-2</sup></th></tr></thead><tbody><tr><td rowspan="3">1</td><td rowspan="3">2.49046</td><td rowspan="3">1.6 ± 0.2</td><td>Fe II</td><td>12.60 ± 0.07</td></tr><tr><td>S II</td><td>12.98 ± 0.91</td></tr><tr><td>O I</td><td>13.32 ± 1.54</td></tr><tr><td rowspan="3">2</td><td rowspan="3">2.49054</td><td rowspan="3">4.1 ± 0.1</td><td>Fe II</td><td>13.61 ± 0.02</td></tr><tr><td>S II</td><td>13.58 ± 0.02</td></tr><tr><td>O I</td><td>15.31 ± 0.24</td></tr></tbody></table>

$$ \begin{array}{l} \text{C3 QSO J0018-0913 } z_{\text{em}} = 0.75593, z_{\text{abs}} = 0.584, \\ \log N(\text{HI}) = 20.11 \pm 0.10 \end{array} $$

We detect in this low-redshift absorber's spectrum the following low-ionization ions: Fe II λλλ 2344 2374 and 2382. The profile is fitted using 11 components, spread over a velocity range of about 200 km s⁻¹, resulting in an abundance for Fe II of log N(Fe II) = 13.87 ± 0.03. The main component is located on the blue edge of the profile and is accounting for about 40 per cent of the total abundance. Also, we derive upper limits from non detection of Zn II λ 2026, log N(Zn II) < 12.41, Cr II λ 2056, log N(Cr II) < 12.97, Ti II λ 3384, log N(Ti II) < 11.57, Mg I λ 2026, log N(Mg I) < 13.04, Na I λ 3303.3 and log N(Na I) < 13.15.

<figure><img src="image_17.png" /><figcaption>**Figure C2.** QSOJ0008-2901.</figcaption></figure>
<table><caption>**Table C3.** Voigt profile fit parameters to the low-ionization species for the $z_{abs} = 0.584 \log N(H\text{i}) = 20.11 \pm 0.1$ absorber towards QSO J0018-0913.</caption><thead><tr><th>Comp.</th><th>z<sub>abs</sub></th><th>b<br>km s<sup>-1</sup></th><th>Ion</th><th>log N<br>cm<sup>-2</sup></th></tr></thead><tbody><tr><td>1</td><td>0.583 04</td><td>5.4 ± 0.3</td><td>Fe II</td><td>13.51 ± 0.04</td></tr><tr><td>2</td><td>0.583 22</td><td>13.0 ± 5.4</td><td>Fe II</td><td>12.60 ± 0.14</td></tr><tr><td>3</td><td>0.583 32</td><td>2.5 ± 0.7</td><td>Fe II</td><td>12.90 ± 0.09</td></tr><tr><td>4</td><td>0.583 39</td><td>3.1 ± 5.3</td><td>Fe II</td><td>12.28 ± 0.13</td></tr><tr><td>5</td><td>0.583 46</td><td>3.3 ± 1.2</td><td>Fe II</td><td>12.78 ± 0.06</td></tr><tr><td>6</td><td>0.583 53</td><td>3.5 ± 3.5</td><td>Fe II</td><td>11.96 ± 0.17</td></tr><tr><td>7</td><td>0.583 65</td><td>13.4 ± 14.9</td><td>Fe II</td><td>12.15 ± 0.43</td></tr><tr><td>8</td><td>0.583 78</td><td>3.8 ± 2.1</td><td>Fe II</td><td>12.69 ± 0.10</td></tr><tr><td>9</td><td>0.583 86</td><td>2.0 ± 3.1</td><td>Fe II</td><td>12.33 ± 0.19</td></tr><tr><td>10</td><td>0.583 97</td><td>6.7 ± 0.8</td><td>Fe II</td><td>12.98 ± 0.03</td></tr><tr><td>11</td><td>0.584 06</td><td>3.8 ± 1.2</td><td>Fe II</td><td>12.57 ± 0.05</td></tr></tbody></table>

The metallicity for this low-redshift sub-DLA is surprisingly low (even considering the $\alpha$-enhancement correction of ~.4 dex), $[Fe/H] = -1.70 \pm 0.13$. It may be an effect of dust depletion, but we are unable to conclude on this particular issue due to the low number of detected ions. The metallicity derived here is therefore to be considered as a lower limit.

There is no coverage of the high-ionization ions due to the low redshift of the absorber.

The parameter fits of the individual components are listed in Table C3 and the corresponding Voigt profile fits are shown in Fig. C3.

<figure><img src="image_18.png" /><figcaption>**Figure C3.** QSOJ0018-0913.</figcaption></figure>

$$ \begin{array}{l} \text{C4 QSOJ0041-4936 } z_{\text{em}} = 3.24, z_{\text{abs}} = 2.248, \\ \log N(\text{HI}) = 20.46 \pm 0.13 \end{array} $$

This spectrum covers many low-ionization transitions associated with the absorber: S II $\lambda$ 1259, Zn II $\lambda$ 2026, Fe II $\lambda$ 1608, Si II $\lambda\lambda$ 1808, 1526 and Al II $\lambda$ 1670. The velocity profile can be conveniently separated into a group of red and blue components. The overall profile is well fitted with four components. Interestingly, the blue group which is weaker than its red counterpart is only detected in S II $\lambda$ 1259, Si II $\lambda$ 1526 and Al II $\lambda$ 1670. Conversely, the red group of components is saturated in the case of the last two transitions. Therefore, these two groups are fitted separately: the blue-component group is fitted with two components using the lines of Si II $\lambda$ 1526 and Al II $\lambda$ 1670. The S II $\lambda$ 1259 line is too blended to provide useful information and we derive an upper limit of $\log N(S\text{i}) < 14.82$. The red-component group includes Zn II $\lambda$ 2026, Fe II $\lambda$ 1608 and Si II $\lambda$ 1808. It is also fitted with two components given the asymmetrical profile of Fe II $\lambda$ 1608. A fifth component redwards of the profile is considered for S II $\lambda$ 1526 and Al II $\lambda$ 1670. The resulting column densities are: $\log N(Fe\text{i}) = 14.43 \pm 0.04$, $\log N(Zn\text{i}) = 11.70 \pm 0.10$, $\log N(Si\text{i}) = 14.78 \pm 0.03$, $\log N(Ni\text{i}) = 13.07 \pm 0.07$ and $\log N(Cr\text{i}) = 13.12 \pm 0.45$. We detect four N I absorption lines N I $\lambda\lambda\lambda\lambda\lambda$ 1199.5, 1134.1, 1134.4 and 1134.9. The profile is fitted with the low-ionization profile in this case. In spite of the modest SNR, a satisfactory fit is found for N I $\lambda\lambda\lambda$ 1134.1, 1134.9 and 1199.5, while the remaining line (N I $\lambda$ 1134.4) appears to be blended. The resulting column density is $\log N(N\text{i}) = 14.03 \pm 0.03$. Finally, the Al II $\lambda$ 1670 line is saturated thus providing a lower limit on the column density: $\log N(Al\text{i}) > 14.06$.

Regarding the high-ionization ions, the C IV doublet $\lambda\lambda$ 1548 and 1550 is covered by the EUADP spectrum. In addition, the
intermediate-ionization Al III transitions $\lambda\lambda$ 1854 and 1862 are present and match well the high-ionization profile. In the case of the C IV doublet, the C IV $\lambda$ 1550 is blended with a broad line in the blue part ($v < -120$ km s$^{-1}$), whereas C IV $\lambda$ 1548 seems blended in the red part ($v > -120$ km s$^{-1}$). In addition, the Al III transition shows absorption features in the red part of the profile only. A six-component profile is used to fit the red part of the profile (using transitions from C IV $\lambda$ 1550, Al III $\lambda\lambda$ 1862 and 1854) and one-component is used to fit the blue part of the profile (using C IV $\lambda$ 1548 at $v \sim -240$ km s$^{-1}$). This results in an estimated column density of Al III log N(Al III) = 12.90 ± 0.01 and a lower limit (blending) for C IV log N(C IV) > 14.56.

The parameter fits are summarized in Table C4 and Voigt profile fits are shown in Fig. C4.

### C5 QSO B0128-2150 $z_{em} = 1.9$, $z_{abs} = 1.857$, $\log N(HI) = 20.21 \pm 0.09$

For this low-redshift absorber, the EUADP spectrum covers a number of the low-ionization ions including Fe II $\lambda\lambda\lambda$ 2374 2260 2249, Ni II $\lambda\lambda\lambda$ 1751 1741 1709, S II $\lambda\lambda\lambda$ 1259 1253 1250 and Si II $\lambda$ 1808. The detected intermediate-ionization transitions, Al III $\lambda\lambda$ 1854 and 1862 show the same velocity profile as the low-ionization ions. A five-component Voigt profile is used to fit Fe II $\lambda\lambda$ 2374 2249, Si II $\lambda$ 1808 S II $\lambda$ 1259, Al III $\lambda$ 1854 and Ni II $\lambda$ 1709. The full absorption profile extends to a velocity range of about 100 km s$^{-1}$. The resulting total column densities are log N(Fe II) = 14.44 ± 0.01, log N(Si II) = 14.82 ± 0.02, log N(S II) = 14.33 ± 0.03, log N(Ni II) = 13.26 ± 0.05 and log N(Al III) = 12.78 ± 0.01. In addition, C II $\lambda$ 1334 is detected but, as often in DLAs, heavily saturated. Finally, the non-detection of both Zn II $\lambda$ 2062 and Mg I $\lambda$ 1827 provides robust column density upper limits: log N(Zn II) < 12.26, and log N(Mg I) < 13.21.

We note that no high-ionization species are covered by this spectrum.

The parameter fits are summarized in Table C5 and Voigt profile fits are shown in Fig. C5.

### C6 QSO J0132-0823 $z_{em} = 1.121$, $z_{abs} = 0.6467$, $\log N(HI) = 20.60 \pm 0.12$

A few ions are covered and detected in this low-redshift absorber's spectrum: Fe II $\lambda\lambda$ 2249 2260, Mg I $\lambda$ 2582 and Ti II $\lambda\lambda$ 3242 and 3384. The absorption is weak, we use the Mg I profile to derive the two main components. The saturated Fe II $\lambda$ 2344 unveils two weak components on either side of the profile. This results in abundances of Fe II log N(Fe II) = 14.96 ± 0.07, of Ti II log N(Ti II) = 12.39 ± 0.11 and of Mg I log N(Mg I) = 12.60 ± 0.04.

The overall SNR (<10) gives a reasonable upper limit for Cr II, using Cr II $\lambda$ 2056, of log N(Cr II) < 13.17. Zn II and C II are also covered, but the best upper limits we can derive are above 16.30.

There is no coverage of the high-ionization ions due to the low redshift of the absorber.

The parameter fits of the individual components are listed in Table C6 and the corresponding Voigt profile fits are shown in Fig. C6.

### C7 QSO B0307-195B $z_{em} = 2.122$, $z_{abs} = 1.788$, $\log N(HI) = 19.0 \pm 0.10$

Many low-ionization ions are detected in this low-redshift absorber including Mg I $\lambda$ 2852, Fe II $\lambda\lambda\lambda\lambda\lambda$ 2374, 1608, 2586, 2344, 2382,

<table><caption>**Table C4.** Voigt profile fit parameters to the low-, intermediate- and high-ionization species for the $z_{abs} = 2.248 \log N(HI) = 20.46 \pm 0.13$ absorber towards QSO J0041-4936.</caption><thead><tr><th>Comp.</th><th>z<sub>abs</sub></th><th>b<br>km s<sup>-1</sup></th><th>Ion</th><th>log N<br>cm<sup>-2</sup></th></tr></thead><tbody><tr><td rowspan="10">1</td><td rowspan="10">2.247 85</td><td rowspan="10">4.6 ± 0.8</td><td>Fe II</td><td>12.01 ± 0.35</td></tr><tr><td>Zn II</td><td>—</td></tr><tr><td>Si II</td><td>12.85 ± 0.04</td></tr><tr><td>Ni II</td><td>—</td></tr><tr><td>Cr II</td><td>—</td></tr><tr><td>Al II</td><td>11.28 ± 0.05</td></tr><tr><td>S II</td><td>&lt;13.24</td></tr><tr><td>N I</td><td>12.38 ± 0.17</td></tr><tr><td>Fe II</td><td>12.01 ± 0.35</td></tr><tr><td>Zn II</td><td>—</td></tr><tr><td>Si II</td><td>13.12 ± 0.02</td></tr><tr><td>Ni II</td><td>—</td></tr><tr><td>Cr II</td><td>—</td></tr><tr><td rowspan="10">2</td><td rowspan="10">2.247 99</td><td rowspan="10">7.3 ± 0.4</td><td>Al II</td><td>11.78 ± 0.02</td></tr><tr><td>S II</td><td>&lt;14.04</td></tr><tr><td>N I</td><td>12.80 ± 0.07</td></tr><tr><td>Fe II</td><td>13.71 ± 0.05</td></tr><tr><td>Zn II</td><td>11.03 ± 0.36</td></tr><tr><td>Si II</td><td>14.35 ± 0.06</td></tr><tr><td>Ni II</td><td>12.80 ± 0.10</td></tr><tr><td>Cr II</td><td>12.73 ± 0.91</td></tr><tr><td>Al II</td><td>&gt;13.11</td></tr><tr><td>S II</td><td>&lt;14.38</td></tr><tr><td>N I</td><td>12.58 ± 0.15</td></tr><tr><td rowspan="10">3</td><td rowspan="10">2.248 40</td><td rowspan="10">10.2 ± 0.9</td><td>Fe II</td><td>14.33 ± 0.05</td></tr><tr><td>Zn II</td><td>11.59 ± 0.09</td></tr><tr><td>Si II</td><td>14.54 ± 0.04</td></tr><tr><td>Ni II</td><td>12.74 ± 0.09</td></tr><tr><td>Cr II</td><td>12.89 ± 0.44</td></tr><tr><td>Al II</td><td>&gt;15.13</td></tr><tr><td>S II</td><td>&lt;14.48</td></tr><tr><td>N I</td><td>14.25 ± 0.04</td></tr><tr><td>Fe II</td><td>—</td></tr><tr><td>Zn II</td><td>—</td></tr><tr><td>Si II</td><td>13.13 ± 0.02</td></tr><tr><td>Ni II</td><td>—</td></tr><tr><td>Cr II</td><td>—</td></tr><tr><td rowspan="10">4</td><td rowspan="10">2.248 52</td><td rowspan="10">3.8 ± 0.2</td><td>Al II</td><td>12.09 ± 0.02</td></tr><tr><td>S II</td><td>—</td></tr><tr><td>N I</td><td>—</td></tr><tr><td>Fe II</td><td>12.84 ± 0.02</td></tr><tr><td>Zn II</td><td>—</td></tr><tr><td>Si II</td><td>13.21 ± 0.01</td></tr><tr><td>Ni II</td><td>—</td></tr><tr><td>Cr II</td><td>—</td></tr><tr><td>Al II</td><td>11.25 ± 0.06</td></tr><tr><td>Si II</td><td>14.32 ± 0.01</td></tr><tr><td>Ni II</td><td>12.28 ± 0.01</td></tr><tr><td rowspan="4">5</td><td rowspan="4">2.248 66</td><td rowspan="4">8.0 ± 0.3</td><td>Al II</td><td>13.58 ± 0.10</td></tr><tr><td>Si II</td><td>12.37 ± 0.01</td></tr><tr><td>Ni II</td><td>13.87 ± 0.01</td></tr><tr><td>Cr II</td><td>12.36 ± 0.01</td></tr><tr><td rowspan="2">6</td><td rowspan="2">2.248 45</td><td rowspan="2">19.6 ± 0.4</td><td>Al II</td><td>12.36 ± 0.01</td></tr><tr><td>Cr II</td><td>—</td></tr><tr><td rowspan="2">7</td><td rowspan="2">2.248 53</td><td rowspan="2">2.6 ± 0.7</td><td>Al II</td><td>12.08 ± 0.01</td></tr><tr><td>Cr II</td><td>—</td></tr></tbody></table>

2600, Si II $\lambda\lambda\lambda$ 1808, 1304, 1526, Mg II $\lambda\lambda$ 2803, 2796, Al II $\lambda$ 1670, Al III $\lambda\lambda$ 1862, 1854, C IV $\lambda\lambda$ 1550, 1548 and Si IV $\lambda\lambda$ 1402, 1393. The absorption profile presents two distinct parts, one in the red (five components), the other one in the blue (three components), with a total velocity ranging about 300 km s$^{-1}$. The fit is
<figure><img src="image_19.png" /><figcaption>Figure C4. QSOJ0041-4936.</figcaption></figure>

<table><caption>**Table C5.** Voigt profile fit parameters to the low-ionization species for the $z_{abs} = 1.857 \log N(H\alpha) = 20.21 \pm 0.09$ absorber towards QSO B0128-2150.</caption><thead><tr><th>Comp.</th><th>z<sub>abs</sub></th><th>b<br>km s<sup>-1</sup></th><th>Ion</th><th>log N<br>cm<sup>-2</sup></th></tr></thead><tbody><tr><td rowspan="5">1</td><td rowspan="5">1.856 10</td><td rowspan="5">11.8 ± 2.1</td><td>Fe II</td><td>12.91 ± 0.06</td></tr><tr><td>Si II</td><td>13.93 ± 0.10</td></tr><tr><td>S II</td><td>12.98 ± 0.29</td></tr><tr><td>Al III</td><td>12.02 ± 0.05</td></tr><tr><td>Ni II</td><td>—</td></tr><tr><td rowspan="5">2</td><td rowspan="5">1.856 27</td><td rowspan="5">4.5 ± 0.7</td><td>Fe II</td><td>13.16 ± 0.04</td></tr><tr><td>Si II</td><td>13.71 ± 0.12</td></tr><tr><td>S II</td><td>13.23 ± 0.12</td></tr><tr><td>Al III</td><td>11.76 ± 0.07</td></tr><tr><td>Ni II</td><td>11.80 ± 0.67</td></tr><tr><td rowspan="5">3</td><td rowspan="5">1.856 41</td><td rowspan="5">4.3 ± 0.3</td><td>Fe II</td><td>13.82 ± 0.01</td></tr><tr><td>Si II</td><td>14.19 ± 0.04</td></tr><tr><td>S II</td><td>13.77 ± 0.04</td></tr><tr><td>Al III</td><td>11.94 ± 0.03</td></tr><tr><td>Ni II</td><td>12.66 ± 0.1</td></tr><tr><td rowspan="5">4</td><td rowspan="5">1.856 55</td><td rowspan="5">7.0 ± 0.2</td><td>Fe II</td><td>14.14 ± 0.01</td></tr><tr><td>Si II</td><td>14.44 ± 0.01</td></tr><tr><td>S II</td><td>13.94 ± 0.03</td></tr><tr><td>Al III</td><td>12.37 ± 0.01</td></tr><tr><td>Ni II</td><td>12.89 ± 0.06</td></tr><tr><td rowspan="5">5</td><td rowspan="5">1.856 76</td><td rowspan="5">4.6 ± 0.2</td><td>Fe II</td><td>13.69 ± 0.01</td></tr><tr><td>Si II</td><td>13.99 ± 0.05</td></tr><tr><td>S II</td><td>13.60 ± 0.05</td></tr><tr><td>Al III</td><td>12.08 ± 0.02</td></tr><tr><td>Ni II</td><td>12.73 ± 0.08</td></tr></tbody></table>

performed using the transitions which are free from any saturation i.e. Fe II λλλλ 2374 1608 2586, Si II λ 1808 and Mg I λ 2852. The Fe II λ 2586 line in particular is not considered for the final fits given the medium quality of the EUADP spectrum around $v = 50$ km s$^{-1}$. The resulting total column densities are: log N(Fe II) = 14.48 ± 0.004, log N(Si II) = 15.0 ± 0.01 and log N(Mg I) = 12.54 ± 0.01. In addition to these measures, the non-detection of Cr II λ 2056, Mn II λ 2594, Ni II λ 1751, and Zn II λ 2062 is used to derive the following upper limits log N(Cr II) < 12.77, log N(Mn II) < 12.13, log N(Ni II) < 13.22 and log N(Zn II) < 12.18.

The high-ionization doublets of C IV λλ 1548 1550 and Si IV λλ 1393 and 1402 are detected in the spectrum albeit indicating strong saturation. A seven-component profile is used to fit these four transitions resulting in lower limits to the total column densities of log N(Si IV) > 14.55 and log N(C IV) > 15.13. Interestingly, in this absorber, the velocity range of the high-ionization ion profile matches the one from the low-ionization ions extending to about 300 km s$^{-1}$.

The resulting parameter fits for the low- and high-ionization profiles are listed in Table C7 and the corresponding Voigt profile fits are shown in Fig. C7.

$$ \begin{array}{l} \textbf{C8 QSO J0427-1302} z_{\text{em}} = 2.166, z_{\text{abs}} = 1.562, \\ \log N(\text{HI}) = 19.35 \pm 0.10 \end{array} $$

The low-ionization transitions in this low-redshift system are well fitted with two components, the redshift and Doppler parameter of which are fixed by a simultaneous fit of Fe II λλλλλ 2344, 2382, 2586,
<figure><img src="image_20.png" /><figcaption>Figure C5. QSOB0128-2150.</figcaption></figure>

<table><caption>**Table C6.** Voigt profile fit parameters to the low-ionization species for the $z_{abs} = 0.647 \log N(HI) = 20.60 \pm 0.12$ absorber towards QSO J0132-0823.</caption><thead><tr><th>Comp.</th><th>z<sub>abs</sub></th><th>b<br>km s<sup>-1</sup></th><th>Ion</th><th>log N<br>cm<sup>-2</sup></th></tr></thead><tbody><tr><td rowspan="3">1</td><td rowspan="3">0.646 12</td><td rowspan="3">10.7 ± 2.3</td><td>Fe II</td><td>13.38 ± 0.08</td></tr><tr><td>Ti II</td><td>11.53 ± 0.44</td></tr><tr><td>Mg I</td><td>10.62 ± 1.76</td></tr><tr><td rowspan="3">2</td><td rowspan="3">0.646 35</td><td rowspan="3">15.6 ± 1.2</td><td>Fe II</td><td>14.72 ± 0.09</td></tr><tr><td>Ti II</td><td>12.15 ± 0.10</td></tr><tr><td>Mg II</td><td>12.37 ± 0.04</td></tr><tr><td rowspan="3">3</td><td rowspan="3">0.646 58</td><td rowspan="3">14.4 ± 2.1</td><td>Fe II</td><td>14.52 ± 0.11</td></tr><tr><td>Ti II</td><td>11.75 ± 0.21</td></tr><tr><td>Mg I</td><td>12.13 ± 0.06</td></tr><tr><td rowspan="3">4</td><td rowspan="3">0.646 77</td><td rowspan="3">10.8 ± 3.0</td><td>Fe II</td><td>13.35 ± 0.13</td></tr><tr><td>Ti II</td><td>11.12 ± 0.77</td></tr><tr><td>Mg I</td><td>11.43 ± 0.19</td></tr></tbody></table>

2600 and Al II λ 1670. The two-component fit shows an interesting asymmetric distribution of Fe II and Al II abundances: the blue component is stronger for Fe II while the red component is stronger for Al II. The resulting column densities are log N(Fe II) = 12.23 ± 0.04 and log N(Al II) = 11.78 ± 0.1. In addition, the non detection of Cr II λ 2056, Mg I λ 2026, Mn II λ 2576, Ni II λ 1741, and Zn II λ 2026 leads to the following upper limits: log N(Cr II) < 12.39,

log N(Mg I) < 12.38, log N(Mn II) < 11.84, log(Ni II) < 13.23 and log N(Zn II) < 11.75.

In addition to these low-ionization transitions, the EUADP spectrum covers several high-ionization species. The doublet of C IV λλλ 1550, 1548 and Si IV λλλ 1393 and 1402 expand a velocity range of about 250 km s⁻¹. The C IV transitions are strongly saturated and Si IV λ 1402 appears to be blended (greater absorption in spite of a lower oscillation factor than Si IV λ 1393). Thus the fit is performed using the Si IV λ 1393 line, considering a total of 12 components, with the redder one being associated with the low-ionization profile (v ~140 km s⁻¹). Many of the strongest components fitted for Si IV λ 1393 match the velocity profiles of the C IV doublet. We obtain log N(Si IV) = 13.9 ± 0.07.

The parameter fits are listed in Table C8 and the corresponding Voigt profile fits are shown in Fig. C8.

$$ \begin{array}{l} \text{C9 QSO PKS0454-220 } z_{\text{em}} = 0.534, z_{\text{abs}} = 0.474, \\ \log N(\text{HI}) = 19.45 \pm 0.03 \end{array} $$

This low-redshift absorption system contains a great number of transitions including three Mn II lines: Mn II λλλλ 2576, 2594, 2606, and seven Fe II lines (four of which are saturated): Fe II λλλλλλλλλ 2249, 2260, 2374, 2344, 2382, 2586 and 2600. It is interesting to notice the presence of a component in the blue part of the saturated lines which is not detected in the weaker transitions. Therefore, the fit is performed in two separate steps: on one hand the unsaturated
<figure><img src="image_21.png" /><figcaption>Figure C6. QSOJ0132-0823.</figcaption></figure>

lines are used to constrain the strongest components, on the other hand, this solution is applied to the saturated profiles to check its validity and to constrain the blue component. The absorption profile results in a total of seven components (five strong components as well as one blue and one red additional weaker components), spread in a velocity range of about 150 km s⁻¹. The column densities derived are log N(Fe II) = 14.71 ± 0.01 and log N(Mn II) = 12.58 ± 0.01.

In this EUADP spectrum, no high-ionization transitions are covered for this low-redshift absorber.

The parameter fits are summarized in Table C9 and Voigt profile fits are shown in Fig. C9.

$$ \text{C10 QSOJ0600-5040 } z_{\text{em}} = 3.13, z_{\text{abs}} = 2.149, \\ \log N(\text{HI}) = 20.4 \pm 0.12 $$

The EUADP spectrum for this absorber covers many low-ionization transitions including Fe II λλλ 1608, 1611, Al II λ 1670, Si II λλλλλ 1193, 1526, 1304, 1808, Zn II λ 2062, Cr II λλλ 2062, 2026, Ni II λλλλ 1709, 1741 and 1751. The absorption profile is clearly multicomponent and covers a large velocity range of about 100 km s⁻¹ based on the strongest transitions (namely Al II λ 1670, Fe II λ 1608, Si II λλλλλ 1193, 1526 and 1304). The profile is well fitted with four components. This velocity profile is then applied to the weakest Zn II λ 2026 line. It reveals a blend in the first two components related to the Cr II λ 2062 line which is therefore fitted simultaneously. The Al II λ 1670 line is saturated, leading to a lower limit estimate in the column density of log N(Al II) > 14.33 based on the four component profile (redshifts and Doppler parameters) described above. The Al III λλλ 1854 and 1862 profiles follow the low-ionization ions. However, a blend in Al III λ 1854 complicates the fit so that the ve-

locity of the first component is fixed to the value derived above. The resulting column densities are: log N(Fe II) = 14.84 ± 0.03, log N(Si II) = 15.08 ± 0.01, log N(Ni II) = 13.62 ± 0.02, log N(Cr II) = 13.10 ± 0.01, log N(Zn II) = 12.11 ± 0.03 and log N(Al III) = 12.78 ± 0.01.

In this EUADP spectrum, the high-ionization ions Si IV λλλ 1393, 1402, and C IV λλλ 1548 and 1550 are covered but are located in the forest, and hence suffer from important blending.

The parameter fits are summarized in Table C10 and Voigt profile fits are shown in Fig. C10.

$$ \text{C11 QSO B1036-2257 } z_{\text{em}} = 3.13, z_{\text{abs}} = 2.533, \\ \log N(\text{HI}) = 19.3 \pm 0.10 $$

A large number of low-ionization elements are detected in the EUADP spectrum including Si II λλλλλ 1190, 1193, 1260, 1526, C II λλλ 1036, 1334, Mg II λλλ 2803 and 2796, Al II λ 1670, Al III λ 1862 and Fe II λλλ 2382, 2600. Based on the Si II λλλ 1193 and 1260 lines which are free from any saturation and blending, 11 components are used to fit the absorption profile. The low-ionization transitions for this system cover a large velocity range of about 200 km s⁻¹. The strongest components of this profile are used to fit Al II λ 1670, Fe II λλλ 2600, 2382 and Al III λ 1862. The resulting column densities are log N(Si II) = 13.64 ± 0.01, log N(Al II) = 12.52 ± 0.01, log N(Al III) = 12.89 ± 0.02 and log N(Fe II) = 12.93 ± 0.01. The profile estimated from the weakest transition is then used to fit the saturated C II λ 1334 revealing a 12th component around v = 0 km s⁻¹. A manual fit using C II λλλ 1036 and 1334 and the previous solution provides the following lower limit for C II log N(C II) > 15.98. Nevertheless, both lines are contaminated
<table><caption>**Table C7.** Voigt profile fit parameters to the low- and high-ionization species for the $z_{\text{abs}} = 1.788$ log N(HI) = 19.00 ± 0.10 absorber towards QSO B0307-195B.</caption><thead><tr><th>Comp.</th><th>z<sub>abs</sub></th><th>b<br>km s<sup>-1</sup></th><th>Ion</th><th>log N<br>cm<sup>-2</sup></th></tr></thead><tbody><tr><td rowspan="3">1</td><td rowspan="3">1.787 44</td><td rowspan="3">7.8 ± 0.1</td><td>Fe II</td><td>13.99 ± 0.01</td></tr><tr><td>Si II</td><td>14.53 ± 0.01</td></tr><tr><td>Mg I</td><td>11.83 ± 0.01</td></tr><tr><td rowspan="3">2</td><td rowspan="3">1.787 63</td><td rowspan="3">4.3 ± 0.1</td><td>Fe II</td><td>13.61 ± 0.01</td></tr><tr><td>Si II</td><td>14.14 ± 0.03</td></tr><tr><td>Mg I</td><td>11.90 ± 0.01</td></tr><tr><td rowspan="3">3</td><td rowspan="3">1.787 88</td><td rowspan="3">8.6 ± 0.4</td><td>Fe II</td><td>13.54 ± 0.01</td></tr><tr><td>Si II</td><td>13.99 ± 0.04</td></tr><tr><td>Mg I</td><td>11.16 ± 0.03</td></tr><tr><td rowspan="3">4</td><td rowspan="3">1.788 47</td><td rowspan="3">9.9 ± 0.1</td><td>Fe II</td><td>13.42 ± 0.02</td></tr><tr><td>Si II</td><td>13.60 ± 0.11</td></tr><tr><td>Mg I</td><td>11.61 ± 0.01</td></tr><tr><td rowspan="3">5</td><td rowspan="3">1.788 63</td><td rowspan="3">8.2 ± 0.2</td><td>Fe II</td><td>13.58 ± 0.01</td></tr><tr><td>Si II</td><td>14.31 ± 0.02</td></tr><tr><td>Mg I</td><td>11.87 ± 0.01</td></tr><tr><td rowspan="3">6</td><td rowspan="3">1.788 85</td><td rowspan="3">8.2 ± 0.2</td><td>Fe II</td><td>13.64 ± 0.01</td></tr><tr><td>Si II</td><td>14.25 ± 0.02</td></tr><tr><td>Mg I</td><td>11.72 ± 0.01</td></tr><tr><td rowspan="3">7</td><td rowspan="3">1.789 29</td><td rowspan="3">7.0 ± 0.7</td><td>Fe II</td><td>13.11 ± 0.03</td></tr><tr><td>Si II</td><td>13.13 ± 0.26</td></tr><tr><td>Mg I</td><td>11.14 ± 0.03</td></tr><tr><td rowspan="3">8</td><td rowspan="3">1.789 49</td><td rowspan="3">8.9 ± 2.0</td><td>Fe II</td><td>12.95 ± 0.05</td></tr><tr><td>Si II</td><td>—</td></tr><tr><td>Mg I</td><td>10.90 ± 0.07</td></tr><tr><td rowspan="2">1</td><td rowspan="2">1.787 48</td><td rowspan="2">19.8 ± 0.3</td><td>Si IV</td><td>13.27 ± 0.01</td></tr><tr><td>C IV</td><td>13.68 ± 0.01</td></tr><tr><td rowspan="2">2</td><td rowspan="2">1.787 96</td><td rowspan="2">15.1 ± 0.6</td><td>Si IV</td><td>13.10 ± 0.03</td></tr><tr><td>C IV</td><td>13.46 ± 0.03</td></tr><tr><td rowspan="2">3</td><td rowspan="2">1.788 26</td><td rowspan="2">18.6 ± 1.1</td><td>Si IV</td><td>13.50 ± 0.03</td></tr><tr><td>C IV</td><td>14.08 ± 0.03</td></tr><tr><td rowspan="2">4</td><td rowspan="2">1.788 65</td><td rowspan="2">19.8 ± 0.5</td><td>Si IV</td><td>14.37 ± 0.02</td></tr><tr><td>C IV</td><td>14.89 ± 0.02</td></tr><tr><td rowspan="2">5</td><td rowspan="2">1.789 21</td><td rowspan="2">32.5 ± 1.3</td><td>Si IV</td><td>13.58 ± 0.02</td></tr><tr><td>C IV</td><td>14.42 ± 0.01</td></tr><tr><td rowspan="2">6</td><td rowspan="2">1.789 70</td><td rowspan="2">18.9 ± 0.6</td><td>Si IV</td><td>13.15 ± 0.02</td></tr><tr><td>C IV</td><td>13.97 ± 0.02</td></tr><tr><td rowspan="2">7</td><td rowspan="2">1.789 81</td><td rowspan="2">5.0 ± 0.3</td><td>Si IV</td><td>12.78 ± 0.02</td></tr><tr><td>C IV</td><td>13.25 ± 0.04</td></tr></tbody></table>

with unrelated absorbers, which prevents us from deriving a robust estimate of the lower limit in CII.

A great number of high-ionization lines are detected in this EUADP spectra including O vi λλ 1031, 1037, N v λλ 1238, 1242, C iv λλ 1548, 1550, Si iv λλ 1393 and 1402. A number of these lines are located in the Lyman α forest (Si iv doublet, N v λ 1242 and O vi λ 1031) and therefore appear to be blended. The C iv doublet is saturated in this case, such that only a lower limit is derived. Only the O vi λ 1037 and N v λ 1238 lines appear free from any saturation or blending, preventing from performing a reasonable fit. A three-component profile is used to fit Si iv λ 1393. The resulting component velocities and Doppler parameters are then used to fit the other lines available. The resulting column densities are log N(Si iv) = 13.71 ± 0.01, log N(C iv) > 17.42.

The parameter fits of the individual components are listed in Table C11 and the corresponding Voigt profile fits are shown in Fig. C11.

$$ \begin{array}{l} \text{C12 QSO J115538.6+053050 z}_{\text{em}} = 3.475, z_{\text{abs}} = 3.327, \\ \log \text{N(HI)} = 21.0 \pm 0.10 \end{array} $$

Many ions are detected in this absorber, such as Si ii λ 1808, S ii λλλλ 1259 1253 1250, Al iii λλ 1854 1862, Ni ii λλ 1370 1317, C iv λλ 1548 1550 and Si iv λλ 1393 and 1402. The low- and intermediate-ionization ions show a similar profile (strong absorption line near v = 65 km s⁻¹) and are therefore fitted together with a seven-component profile. Only the non-saturated lines, Ni ii λλ 1370 1317, Si ii λ 1808 and S ii λ 1253 are used in the derivation of the parameter. The ions Al ii λ 1670, C ii λλλλ 1036 and 1334 are also detected but not fitted due to strong saturation. Al iii have not been fitted due to a blend in the Al iii λ 1862 line. The resulting abundances for the low-ionization ions are log N(Si ii) = 15.93 ± 0.01, log N(S ii) = 15.31 ± 0.01 and log N(Ni ii) = 13.74 ± 0.01. A non-detection from MgI λ 1827 gives the following upper limit: log N(Mg I) < 13.33.

The high-ionization ions C iv λλ 1548 1550 and Si iv λλλλ 1402 are fitted using a three-component profile, extending to about 200 km s⁻¹. Si iv λ 1393 is not considered for the fit as it is blended bluewards the bluest component of the fit (v ~ 150 km s⁻¹). This gives the following abundances for the high-ionization transitions: log N(C iv) = 13.71 ± 0.01 and log N(Si iv) = 13.56 ± 0.01. We note that, although the reddest components for both low- and high-ionization profiles have velocities that differ by about 20 km s⁻¹, they both stand out from the bluer absorption profile.

The parameter fits of the individual components are listed in Table C12 and the corresponding Voigt profile fits are shown in Fig. C12.

$$ \begin{array}{l} \text{C13 QSO LBQS 1232+0815 z}_{\text{em}} = 2.57, z_{\text{abs}} = 1.72, \\ \log \text{N(HI)} = 19.48 \pm 0.13 \end{array} $$

The EUADP spectrum for this DLA absorber covers the following low- and intermediate-ionization transitions: Fe ii λλλλλ 2382, 2374, 2344, 1608, Al iii λλλλ 1862, 1854, Si ii λλλλ 1526 (blended) and 1808. It also covers C ii λ 1334, which is saturated. The low- and intermediate-ionization profiles are well fitted together with the transitions Fe ii λλ 2382, 2344, Al iii λλλλ 1854, 1862 and Si ii λ 1808 using six components spread over ~200 km s⁻¹, resulting in the following abundances log N(Fe ii) = 13.50 ± 0.01, log N(Si ii) = 14.41 ± 0.01 and log N(Al iii) = 13.28 ± 0.01. We derived upper limits from non detection for S ii λ 1253, log N(S ii) < 14.18, Cr ii λ 2056, log N(Cr ii) < 12.38, Mg i λ 2026, log N(Mg i) < 12.21, Ni ii λ 1751, log N(Ni ii) < 13.05, and Zn ii λ 2026, log N(Zn ii) < 11.58.

The high-ionization ions detected in the spectrum are Si iv λλλλ 1393, 1402, C iv λλλλ 1548 and 1550. The C iv transition lines are highly saturated and contaminated by an apparent blend, they are therefore not consider for the fit. From the less saturated Si iv transition lines, a five-component profile provides the following lower limit log N(Si iv) > 14.67. We notice that the low- and high-ionization ions seem to share the same components.

The parameter fits of the individual components are listed in Table C13 and the corresponding Voigt profile fits are shown in Fig. C13.

$$ \begin{array}{l} \text{C14 QSO J1330-2522 z}_{\text{em}} = 3.91, z_{\text{abs}} = 2.654, \\ \log \text{N(HI)} = 19.56 \pm 0.13 \end{array} $$

This EUADP spectrum covers six ions, Si iv λλλλ 1393, 1402, Si ii λ 1526, Al ii λ 1670, Al iii λλλλ 1854 and 1862. Many of these transitions
<figure><img src="image_22.png" /><figcaption>Figure C7. QSOB0307-195B.</figcaption></figure>

<table><caption>**Table C8.** Voigt profile fit parameters to the low- and high-ionization species for the $z_{abs}$ = 1.562 log N(HI) = 19.35 ± 0.10 absorber towards QSO J0427-1302.</caption><thead><tr><th>Comp.</th><th>z<sub>abs</sub></th><th>b<br>km s<sup>-1</sup></th><th>Ion</th><th>log N<br>cm<sup>-2</sup></th></tr></thead><tbody><tr><td>1</td><td>1.563 1845</td><td>7.2 ± 1.4</td><td>Al II</td><td>11.78 ± 0.10</td></tr><tr><td></td><td></td><td></td><td>Fe II</td><td>–</td></tr><tr><td>2</td><td>1.563 2172</td><td>2.9 ± 0.6</td><td>Al III</td><td>–</td></tr><tr><td></td><td></td><td></td><td>Fe II</td><td>12.23 ± 0.04</td></tr><tr><td>1</td><td>1.56065</td><td>17.4 ± 2.7</td><td>Si IV</td><td>12.96 ± 0.08</td></tr><tr><td>2</td><td>1.56075</td><td>3.1 ± 2.4</td><td>Si IV</td><td>12.31 ± 0.22</td></tr><tr><td>3</td><td>1.56089</td><td>4.6 ± 1.0</td><td>Si IV</td><td>12.73 ± 0.06</td></tr><tr><td>4</td><td>1.56101</td><td>1.5 ± 0.7</td><td>Si IV</td><td>12.93 ± 0.62</td></tr><tr><td>5</td><td>1.56126</td><td>23.8 ± 8.3</td><td>Si IV</td><td>12.85 ± 0.12</td></tr><tr><td>6</td><td>1.56143</td><td>1.2 ± 2.0</td><td>Si IV</td><td>12.13 ± 0.39</td></tr><tr><td>7</td><td>1.56165</td><td>12.8 ± 1.0</td><td>Si IV</td><td>13.27 ± 0.03</td></tr><tr><td>8</td><td>1.56197</td><td>12.7 ± 1.8</td><td>Si IV</td><td>12.81 ± 0.04</td></tr><tr><td>9</td><td>1.56228</td><td>6.4 ± 2.5</td><td>Si IV</td><td>12.33 ± 0.08</td></tr><tr><td>10</td><td>1.56270</td><td>25.4 ± 5.2</td><td>Si IV</td><td>12.49 ± 0.08</td></tr><tr><td>11</td><td>1.56309</td><td>2.0 ± 2.0</td><td>Si IV</td><td>12.35 ± 0.17</td></tr><tr><td>12</td><td>1.56321</td><td>6.4 ± 0.6</td><td>Si IV</td><td>13.15 ± 0.03</td></tr></tbody></table>

are blended and/or saturated, such that only Al II λ 1670 and Al III λ 1854 have been fitted. The asymmetry of both lines suggests a two-component profile, resulting in the following abundances: log N(Al III) = 12.62 ± 0.02 and log N(Al II) = 12.18 ± 0.2. We derive

an upper limit from non detection of Ni II λ 1741: log N(Ni II) < 13.22.

In this spectrum, the high-ionization ions Si IV λλ 1393, 1402 and C IV λλ 1548 and 1550 are covered but suffer from severe blending, such that no fit has been performed.

The parameter fits of the individual components are listed in Table C14 and the corresponding Voigt profile fits are shown in Fig. C14.

$$ \text{C15 QSO J1356-1101 } z_{\text{em}} = 3.006, z_{\text{abs}} = 2.397, \\ \log \text{N(HI)} = 19.85 \pm 0.08 $$

The spectrum covers four Fe II lines and two Si IV lines associated with the absorber: Fe II λλλλλ 2600 2344 2382 2586 and Si IV λλ 1393 and 1402. The low-ionization profile is well fitted with a six-component profile in the red, and a single blue component isolated from the red group of components by about 250 km s⁻¹. The resulting column density is log N(Fe II) = 13.44 ± 0.01. We derived upper limits from the non-detection of several transitions: Cr II λ 2056, log N(Cr II) < 12.64, Mn II λ 2576, log N(Mn II) < 12.07, Ni II λ 1317, log N(Ni II) < 12.76, and Zn II λ 2062, log N(Zn II) < 12.38.

The high-ionization ion Si IV λλ 1393 and 1402 is detected but not fitted because it is heavily saturated.

The parameter fits of the individual components are listed in Table C15 and the corresponding Voigt profile fits are shown in Fig. C15.
<figure><img src="image_23.png" /><figcaption>Figure C8. QSOJ0427-1302.</figcaption></figure>

<table><caption>**Table C9.** Voigt profile fit parameters to the low-ionization species for the $z_{abs} = 0.474 \log N(H\alpha) = 19.45 \pm 0.03$ absorber towards QSO PKS 0454-220.</caption><thead><tr><th>Comp.</th><th>z<sub>abs</sub></th><th>b<br>km s<sup>-1</sup></th><th>Ion</th><th>log N<br>cm<sup>-2</sup></th></tr></thead><tbody><tr><td rowspan="2">1</td><td rowspan="2">0.47405</td><td rowspan="2">14.3 ± 0.6</td><td>Fe II</td><td>12.39 ± 0.02</td></tr><tr><td>Mn II</td><td>11.12 ± 0.07</td></tr><tr><td rowspan="2">2</td><td rowspan="2">0.47422</td><td rowspan="2">14.5 ± 0.2</td><td>Fe II</td><td>13.38 ± 0.01</td></tr><tr><td>Mn II</td><td>11.46 ± 0.03</td></tr><tr><td rowspan="2">3</td><td rowspan="2">0.47432</td><td rowspan="2">4.0 ± 0.1</td><td>Fe II</td><td>14.00 ± 0.02</td></tr><tr><td>Mn II</td><td>11.65 ± 0.02</td></tr><tr><td rowspan="2">4</td><td rowspan="2">0.47439</td><td rowspan="2">10.0 ± 0.2</td><td>Fe II</td><td>14.26 ± 0.01</td></tr><tr><td>Mn II</td><td>12.09 ± 0.01</td></tr><tr><td rowspan="2">5</td><td rowspan="2">0.47448</td><td rowspan="2">18.5 ± 0.2</td><td>Fe II</td><td>14.12 ± 0.01</td></tr><tr><td>Mn II</td><td>12.03 ± 0.01</td></tr><tr><td rowspan="2">6</td><td rowspan="2">0.47466</td><td rowspan="2">6.5 ± 0.1</td><td>Fe II</td><td>13.81 ± 0.01</td></tr><tr><td>Mn II</td><td>11.48 ± 0.04</td></tr><tr><td rowspan="2">7</td><td rowspan="2">0.47468</td><td rowspan="2">14.9 ± 0.3</td><td>Fe II</td><td>13.11 ± 0.04</td></tr><tr><td>Mn II</td><td>11.50 ± 0.06</td></tr></tbody></table>

$$ \textbf{C16 QSO J1621-0042} \quad z_{em} = 3.7, \quad z_{abs} = 3.104, \\ \log N(H\alpha) = 19.7 \pm 0.20 $$

The EUADP spectrum probing this high-redshift subDLA covers many transitions associated with the absorber such as Fe II λλλ 1608, 1611, C II λλλ 1036, 1334, S II λλλλ 1250, 1253, 1259, Si II λλλλλλ 1190, 1193, 1260, 1304, 1526, Si IV λλλ 1393, 1402(partly), C IV λλλ 1548 and 1550. Most of these lines are heavily blended (Si II λλλλ 1190, 1304, 1260) or saturated (C II λλλ 1334 and 1036), but the wide coverage and SNR of the spectrum provide enough elements to derive the different parameters.

The low-ionization ions are fitted with a 12-component profile, with a broad velocity range (about 400 km s⁻¹). The component with the highest velocity (v ~ 400 km s⁻¹) is identified in three transitions: Si II λλλ 1190 and C II λ 1334. The low velocity components are less affected by the blending and are therefore well fitted, but the

information about the group of component between v ~ 100 km s⁻¹ and v ~ 250 km s⁻¹ are only derived from Fe II λ 1608 and Si II λ 1526. For C II in particular, this group of component is saturated so that a lower limit is derived based on the low velocity components log N(C II) < 14.41. The S II line is most probably blended as its profile does not match the other low-ionization ions. The resulting abundances for the low-ionization ions are log N(Fe II) = 13.30 ± 0.04 and log N(Si II) = 13.78 ± 0.03.

The high-ionization ion components are also detected with a broad velocity range (400 km s⁻¹). The EUADP spectrum does not fully cover the Si IV λ 1402 transition, thus preventing a proper fit. However, the blue part of Si IV λ 1402 matches the blue parts of Si IV λ 1393 and the C IV lines, confirming the detection of Si IV and C IV. It is interesting to note that in this case no satisfactory solutions could be found to fit simultaneously the Si IV and C IV doublets. To check the wavelength calibration of the spectrum, the Si II λλλ 1526 and 1190 lines (which fall on two different arm of the spectrograph) are fitted independently. The redshifts determined for these transitions are consistent with each other (z = 3.10408 and z = 3.10409) thus indicating no systematic shift in the spectrum. Therefore, the Si IV and C IV transitions are fitted separately, with different Doppler parameters and velocities as seen in Table C16. The 14-component fit results in log N(Si IV) = 14.24 ± 0.03 and log N(C IV) = 14.71 ± 0.01.

The parameter fits of the individual components are listed in Table C16 and the corresponding Voigt profile fits are shown in Fig. C16.

$$ \textbf{C17 QSO 4C12.59} \quad z_{em} = 1.792, \quad z_{abs} = 0.531, \\ \log N(H\alpha) = 20.7 \pm 0.09 $$

This very low-redshift DLA absorber presents a few absorption features in the EUADP spectrum partly due the limited wavelength coverage and an overall low SNR. The Fe II ion is detected in the following transitions Fe II λλλλ 2344, 2382 and 2374. The Fe II λ 2382 line is saturated. A satisfactory fit for the remaining transitions
<figure><img src="image_24.png" /><figcaption>Figure C9. QSOPKS0454-220.</figcaption></figure>

Fe II λλλ 2374 and 2344 is found with six components. The resulting column density is log N(Fe II) = 14.26 ± 0.08. The C II λ 2325 line is covered but not detected. The resulting upper limit is log N(C II) < 11.36.

No high-ionization ions are covered in this EUADP spectrum.

The parameter fits of the individual components are listed in Table C17 and the corresponding Voigt profile fits are shown in Fig. C17.

$$
\begin{array}{l}
\text{C18 QSO LBQS2114-4347 } z_{\text{em}} = 2.04, z_{\text{abs}} = 1.912, \\
\log N(\text{HI}) = 19.5 \pm 0.10
\end{array}
$$

The EUADP spectrum of this quasar covers the following low-ionization ions: Si II λλλ 1304 1526, Mg II λλλ 2796 2803, Fe II λλλλλλλλλ 2600 1608 2260 2344 2374 2586, Al II λλλ 1670 and C II λλλ 1334. An 11-component fit is used to describe the lines free from saturations and blends, namely Si II λλλ 1526 1304 and Fe II λλλλλ 1608 2374 and 2586.

This results in the following column densities: log N(Si II) = 14.39 ± 0.02, log N(Fe II) = 14.02 ± 0.01, log N(Al II) = 13.00 ± 0.01 and log N(Mg II) = 14.40 ± 0.01. In addition, the non-

detections in the spectrum provide further upper limits as follows: Al III λ 1854, log N(Al III) < 12.09, Cr II λ 2056, log N(Cr II) < 12.77, Mn II λ 2576, log N(Mn II) < 12.24, Ni II λ 1317, log N(Ni II) < 12.88, S II λ 1253, log N(S II) < 13.97, and Zn II λ 2026, log N(Zn II) < 12.17.

A four-component profile is used to fit the high-ionization ions: C IV λλλ 1548 1550 and Si IV λλλ 1393 and 1402. The resulting column densities are log N(Si IV) = 13.43 ± 0.01 and log N(C IV) = 14.39 ± 0.01.

The parameter fits of the individual components are listed in Table C18 and the corresponding Voigt profile fits are shown in Fig. C18.

$$
\begin{array}{l}
\text{C19 QSO B2126-15 } z_{\text{em}} = 3.268, z_{\text{abs}} = 2.638, \\
\log N(\text{HI}) = 19.25 \pm 0.15
\end{array}
$$

This EUADP spectrum covers the following transitions associated with the absorber: Ni II λλλλλ 1709 1741 1751, Si II λλλ 1808, Fe II λλλλλλλλ 2586 1608 2249 2600 2382 and Al III λλλI 1854 and 1862. The good quality of the spectrum and the presence of non blended lines enables a robust 3-component fit of the low-ionization ions
<table><caption>**Table C10.** Voigt profile fit parameters to the low- and intermediate-ionization species for the $z_{abs} = 2.533 \log N(HI) = 20.4 \pm 0.12$ absorber towards QSO J060008.1-504036.</caption><thead><tr><th>Comp.</th><th>z<sub>abs</sub></th><th>b<br>km s<sup>-1</sup></th><th>Ion</th><th>log N<br>cm<sup>-2</sup></th></tr></thead><tbody><tr><td rowspan="7">1</td><td rowspan="7">2.14895</td><td rowspan="7">2.2 ± 0.7</td><td>Fe II</td><td>13.22 ± 0.04</td></tr><tr><td>Si II</td><td>—</td></tr><tr><td>Ni II</td><td>12.06 ± 0.18</td></tr><tr><td>Cr II</td><td>11.50 ± 0.22</td></tr><tr><td>Zn II</td><td>—</td></tr><tr><td>Al III</td><td>11.60 ± 0.02</td></tr><tr><td>Al II</td><td>>14.2</td></tr><tr><td rowspan="7">2</td><td rowspan="7">2.14917</td><td rowspan="7">14.1 ± 0.4</td><td>Fe II</td><td>14.1 ± 0.01</td></tr><tr><td>Si II</td><td>14.55 ± 0.02</td></tr><tr><td>Ni II</td><td>13.16 ± 0.03</td></tr><tr><td>Cr II</td><td>12.33 ± 0.06</td></tr><tr><td>Zn II</td><td>—</td></tr><tr><td>Al III</td><td>12.20 ± 0.01</td></tr><tr><td>Al II</td><td>>13.1</td></tr><tr><td rowspan="7">3</td><td rowspan="7">2.14959</td><td rowspan="7">9.1 ± 0.3</td><td>Fe II</td><td>14.58 ± 0.01</td></tr><tr><td>Si II</td><td>14.84 ± 0.01</td></tr><tr><td>Ni II</td><td>13.29 ± 0.02</td></tr><tr><td>Cr II</td><td>12.83 ± 0.01</td></tr><tr><td>Zn II</td><td>11.97 ± 0.03</td></tr><tr><td>Al III</td><td>12.54 ± 0.01</td></tr><tr><td>Al II</td><td>>13.50</td></tr><tr><td rowspan="7">4</td><td rowspan="7">2.14986</td><td rowspan="7">4.7 ± 0.3</td><td>Fe II</td><td>14.26 ± 0.06</td></tr><tr><td>Si II</td><td>14.21 ± 0.03</td></tr><tr><td>Ni II</td><td>12.81 ± 0.04</td></tr><tr><td>Cr II</td><td>12.54 ± 0.02</td></tr><tr><td>Zn II</td><td>11.56 ± 0.06</td></tr><tr><td>Al III</td><td>11.79 ± 0.02</td></tr><tr><td>Al II</td><td>>13.10</td></tr></tbody></table>

with Fe II λλλ 1608 2586, Si II λ 1808 and Ni II λλλλ 1741 1751 and 1709. The apparent shift in Fe II λ 2586 is thought to originate from a poor continuum fit. The resulting abundances are log N(Fe II) = 14.05 ± 0.01, log N(Si II) = 14.67 ± 0.02, log N(Ni II) = 13.15 ± 0.01. We derive an upper limit from the non detection of Zn II λ 2026: log N(Zn II) < 11.58.

The intermediate-ionization transitions Al III λλλ 1854 and 1862 do not share the same absorption profile as the low-ionization ions (except for the strong narrow line in the middle of both profiles). These are therefore fitted separately with a five-component profile. The resulting column density is log N(Al III) = 13.24 ± 0.02.

The high-ionization transitions Si IV λλλ 1398 and 1402 are clearly detected. However these lines are both blended and saturated, so that no fit are attempted.

The parameter fits of the individual components are listed in Table C19 and the corresponding Voigt profile fits are shown in Fig. C19.

$$ \begin{array}{l} \textbf{C20 QSO B2126-15} \quad z_{\text{em}} = 3.268, z_{\text{abs}} = 2.769, \\ \log N(\text{HI}) = 19.2 \pm 0.15 \end{array} $$

Many lines associated with the absorber are detected in this EUADP spectrum: Fe II λλλλλλλλ 2586 2374 2344 1608 1144 2382 2600, Si II λλλλλ 1808 1526 1190, C II λλλ 1334 1036, Al II λ 1670, Al III λλλ 1862 1854, C IV λλλ 1550 1548 and Si IV λλλ 1402 and 1393.

The low-ionization ions are fitted considering the non blended lines, Fe II λ 2344, Si II λλλ 1808, 1526 and Al II λ 1670. This resulted in a nine-component profile with a 250 km s⁻¹ velocity range. The transition Fe II λ 2374 is not considered for the final fit due to the complexity in the continuum placement in this portion of the spectrum. The C II line is strongly saturated and

<figure><img src="image_25.png" /><figcaption>**Figure C10.** QSOJ0600-5040.</figcaption></figure>
<table><caption>**Table C11.** Voigt profile fit parameters to the low- and high-ionization species for the $z_{abs} = 2.533 \log N(H_1) = 19.3 \pm 0.10$ absorber towards QSO B1036-2257.</caption><thead><tr><th>Comp.</th><th>z<sub>abs</sub></th><th>b<br>km s<sup>-1</sup></th><th>Ion</th><th>log N<br>cm<sup>-2</sup></th><th>Comp.</th><th>z<sub>abs</sub></th><th>b<br>km s<sup>-1</sup></th><th>Ion</th><th>log N<br>cm<sup>-2</sup></th></tr></thead><tbody><tr><td rowspan="5">1</td><td rowspan="5">2.53132</td><td rowspan="5">5.4 ± 0.1</td><td>Si II</td><td>13.19 ± 0.01</td><td rowspan="5">1</td><td rowspan="5">2.53143</td><td rowspan="5">12.9 ± 0.6</td><td>C IV</td><td>12.97 ± 0.02</td></tr><tr><td>Fe II</td><td>12.65 ± 0.01</td><td>Si IV</td><td>12.83 ± 0.02</td></tr><tr><td>Al II</td><td>12.16 ± 0.01</td><td>C IV</td><td>12.98 ± 0.02</td></tr><tr><td>Mg II</td><td>13.20 ± 0.04</td><td>Si IV</td><td>12.74 ± 0.02</td></tr><tr><td>C II</td><td>14.00</td><td>C IV</td><td>12.83 ± 0.02</td></tr><tr><td rowspan="5">2</td><td rowspan="5">2.53152</td><td rowspan="5">11.3 ± 0.4</td><td>Si II</td><td>12.87 ± 0.03</td><td rowspan="5">4</td><td rowspan="5">2.53294</td><td rowspan="5">13.2 ± 2.5</td><td>Si IV</td><td>12.32 ± 0.04</td></tr><tr><td>Fe II</td><td>—</td><td>C IV</td><td>13.9 ± 0.01</td></tr><tr><td>Al II</td><td>11.77 ± 0.03</td><td>Si IV</td><td>12.91 ± 0.01</td></tr><tr><td>Mg II</td><td>12.71 ± 0.03</td><td>C IV</td><td>>13.85</td></tr><tr><td>C II</td><td>13.81 ± 0.01</td><td>Si IV</td><td>12.78 ± 0.02</td></tr><tr><td rowspan="5">3</td><td rowspan="5">2.53178</td><td rowspan="5">2.2 ± 0.2</td><td>Si II</td><td>11.80 ± 0.10</td><td rowspan="5">6</td><td rowspan="5">2.53340</td><td rowspan="5">5.4 ± 4.4</td><td>C IV</td><td>>16.57</td></tr><tr><td>Fe II</td><td>—</td><td>Si IV</td><td>12.98 ± 0.01</td></tr><tr><td>Al II</td><td>11.14 ± 0.03</td><td>C IV</td><td>>17.35</td></tr><tr><td>Mg II</td><td>11.49 ± 0.21</td><td>Si IV</td><td>13.15 ± 0.01</td></tr><tr><td>C II</td><td>12.7</td><td></td><td></td></tr><tr><td rowspan="5">4</td><td rowspan="5">2.53197</td><td rowspan="5">2.1 ± 0.2</td><td>Si II</td><td>12.47 ± 0.06</td><td rowspan="5">7</td><td rowspan="5">2.53358</td><td rowspan="5">3.0 ± 2.6</td><td></td><td></td></tr><tr><td>Fe II</td><td>—</td><td></td><td></td></tr><tr><td>Al II</td><td>11.32 ± 0.02</td><td></td><td></td></tr><tr><td>Mg II</td><td>12.37 ± 0.06</td><td></td><td></td></tr><tr><td>C II</td><td>13.60</td><td></td><td></td></tr><tr><td rowspan="5">5</td><td rowspan="5">2.53220</td><td rowspan="5">4.3 ± 2.1</td><td>Si II</td><td>11.49 ± 0.13</td><td rowspan="5"></td><td rowspan="5"></td><td rowspan="5"></td><td></td><td></td></tr><tr><td>Fe II</td><td>—</td><td></td><td></td></tr><tr><td>Al II</td><td>—</td><td></td><td></td></tr><tr><td>Mg II</td><td>11.19 ± 0.43</td><td></td><td></td></tr><tr><td>C II</td><td>13.00</td><td></td><td></td></tr><tr><td rowspan="5">6</td><td rowspan="5">2.53248</td><td rowspan="5">5.3 ± 0.9</td><td>Si II</td><td>12.09 ± 0.04</td><td rowspan="5"></td><td rowspan="5"></td><td rowspan="5"></td><td></td><td></td></tr><tr><td>Fe II</td><td>—</td><td></td><td></td></tr><tr><td>Al II</td><td>—</td><td></td><td></td></tr><tr><td>Mg II</td><td>12.11 ± 0.07</td><td></td><td></td></tr><tr><td>C II</td><td>14.00</td><td></td><td></td></tr><tr><td rowspan="5">7</td><td rowspan="5">2.53275</td><td rowspan="5">7.8 ± 2.3</td><td>Si II</td><td>11.95 ± 0.05</td><td rowspan="5"></td><td rowspan="5"></td><td rowspan="5"></td><td></td><td></td></tr><tr><td>Fe II</td><td>—</td><td></td><td></td></tr><tr><td>Al II</td><td>—</td><td></td><td></td></tr><tr><td>Mg II</td><td>11.27 ± 0.48</td><td></td><td></td></tr><tr><td>C II</td><td>>15.90</td><td></td><td></td></tr><tr><td rowspan="5">8</td><td rowspan="5">2.53291</td><td rowspan="5">7.1 ± 1.5</td><td>Si II</td><td>12.09 ± 0.04</td><td rowspan="5"></td><td rowspan="5"></td><td rowspan="5"></td><td></td><td></td></tr><tr><td>Fe II</td><td>—</td><td></td><td></td></tr><tr><td>Al II</td><td>—</td><td></td><td></td></tr><tr><td>Mg II</td><td>12.11 ± 0.07</td><td></td><td></td></tr><tr><td>C II</td><td>>15.00</td><td></td><td></td></tr><tr><td rowspan="5">9</td><td rowspan="5">2.53313</td><td rowspan="5">4.0 ± 2.0</td><td>Si II</td><td>11.60 ± 0.04</td><td rowspan="5"></td><td rowspan="5"></td><td rowspan="5"></td><td></td><td></td></tr><tr><td>Fe II</td><td>—</td><td></td><td></td></tr><tr><td>Al II</td><td>—</td><td></td><td></td></tr><tr><td>Mg II</td><td>12.14 ± 0.06</td><td></td><td></td></tr><tr><td>C II</td><td>>14.30</td><td></td><td></td></tr><tr><td rowspan="5">10</td><td rowspan="5">2.53332</td><td rowspan="5">5.6 ± 0.3</td><td>Si II</td><td>12.65 ± 0.01</td><td rowspan="5"></td><td rowspan="5"></td><td rowspan="5"></td><td></td><td></td></tr><tr><td>Fe II</td><td>12.31 ± 0.01</td><td></td><td></td></tr><tr><td>Al II</td><td>—</td><td></td><td></td></tr><tr><td>Mg II</td><td>12.52 ± 0.04</td><td></td><td></td></tr><tr><td>C II</td><td>13.8</td><td></td><td></td></tr><tr><td rowspan="5">11</td><td rowspan="5">2.53356</td><td rowspan="5">5.9 ± 0.7</td><td>Si II</td><td>12.32 ± 0.03</td><td rowspan="5"></td><td rowspan="5"></td><td rowspan="5"></td><td></td><td></td></tr><tr><td>Fe II</td><td>—</td><td></td><td></td></tr><tr><td>Al II</td><td>11.42 ± 0.02</td><td></td><td></td></tr><tr><td>Mg II</td><td>12.35 ± 0.04</td><td></td><td></td></tr><tr><td>C II</td><td>13.55</td><td></td><td></td></tr><tr><td rowspan="5">12</td><td rowspan="5">2.53382</td><td rowspan="5">5.0 ± 0.2</td><td>Si II</td><td>12.82 ± 0.01</td><td rowspan="5"></td><td rowspan="5"></td><td rowspan="5"></td><td></td><td></td></tr><tr><td>Fe II</td><td>12.30 ± 0.01</td><td></td><td></td></tr><tr><td>Al II</td><td>11.80 ± 0.01</td><td></td><td></td></tr><tr><td>Mg II</td><td>12.58 ± 0.03</td><td></td><td></td></tr><tr><td>C II</td><td>13.70</td><td></td><td></td></tr></tbody></table>
<figure><img src="image_26.png" /><figcaption>Figure C11. QSOB1036-2257.</figcaption></figure>

therefore no fit could be performed on this transition. The AlIIλ 1670 transition is saturated, therefore resulting in a lower limit for the column density (log N(AlII) < 14.05). The fit results in the following column densities: log N(FeII) = 14.17 ± 0.01 and log N(SiII) = 14.79 ± 0.01. In addition, the non-detections led to the following upper limits: CrIIλ 2056, log N(CrII) < 12.40, MnIIλ 2606, log N(MnII) < 12.28, and ZnIIλ 2062, log N(ZnII) < 11.95.

The intermediate- and high-ionization ions AlIIIλλ 1854 1862 and SiIVλ 1402 are fitted together given the similarities in their absorption profile. The SiIVλ 1393 transition is not considered because of an unidentified blending in the red part of the profile. The blending does not match any transition from the absorber at redshift $z_{abs} = 2.638$. The nine-component profile of about 200 km s⁻¹ and results in the following column densities log N(SiIV) = 13.84 ± 0.13 and log N(AlIII) = 13.11 ± 0.01. The CIV doublet is also covered by the data but the CIV λ 1548 line is saturated and both profiles show evidence for the presence of blending. It is interesting to note that the CIV doublet presents some components far in the red (up to ~240 km s⁻¹) which are not seen in SiIV. The OVIλλ 1031 and 1037 lines are also detected, but they are blended as often the case in the Ly α forest.

The parameter fits of the individual components are listed in Table C20 and the corresponding Voigt profile fits are shown in Fig. C20.

$$ \begin{array}{l} \text{C21 QSO LBQS2132-4321 } z_{\text{em}} = 2.42, z_{\text{abs}} = 1.916, \\ \log N(\text{HI}) = 20.74 \pm 0.09 \end{array} $$

This EUADP spectrum provides the coverage of many ions associated with the absorber, often free from blending and with a good SNR. The low-ionization ions detected are SiIIλλλλλλλλ 1190 1304 1808 1253 1250 1260 1193, FeIIλλλλ 1608 2260 2249, CrIIλ 2056, NiIIλλλλ 1741 1709, ZnIIλλ 2026 and SIIλλλλ 1250 and 1253. The profile presents two distinct groups of components spread over about 300 km s⁻¹: the weak components, only detected in large oscillator strength ions and the strong components, detected in all low-ionization ions and saturated otherwise. Therefore, the column densities of the strongest components are measured from the small oscillator strength ions only. We fit SiIIλ 1808, FeIIλ 2260, CrIIλλλλ 2056 2026, NiIIλλλλ 1741 1709 and ZnIIλλ 2026 with four components. The intermediate ion AlIIIλ 1854 which presents the same components (among others) is added to the fit. The remaining weak group is fitted with 3 components for SiII, AlIII and FeII. In this latter fit, some parameters such as the Doppler-parameter are fixed during the process because of a rather low SNR and/or blending. We detected a contamination in the third component of SiIIλ 1808, based on SiIIλλλλ 1526 and 1304, we therefore fitted the first three red components fixing the doppler parameter and column density of the third component of SiII. The fit results in the following column densities: log N(SiII) = 15.75 ± 0.02,
<table><caption>**Table C12.** Voigt profile fit parameters to the low- and high-ionization species for the $z_{abs} = 3.327 \log N(HI) = 21.0 \pm 0.10$ absorber towards QSO J15538.6+053050.</caption><thead><tr><th>Comp.</th><th>z<sub>abs</sub></th><th>b<br>km s<sup>-1</sup></th><th>Ion</th><th>log N<br>cm<sup>-2</sup></th></tr></thead><tbody><tr><td rowspan="3">1</td><td rowspan="3">3.325 55</td><td rowspan="3">5.9 ± 0.1</td><td>Ni II</td><td>12.84 ± 0.01</td></tr><tr><td>S II</td><td>14.14 ± 0.01</td></tr><tr><td>Si II</td><td>—</td></tr><tr><td rowspan="3">2</td><td rowspan="3">3.325 75</td><td rowspan="3">33.8 ± 0.1</td><td>Al III</td><td>—</td></tr><tr><td>Ni II</td><td>13.35 ± 0.01</td></tr><tr><td>S II</td><td>14.66 ± 0.01</td></tr><tr><td rowspan="3">3</td><td rowspan="3">3.326 06</td><td rowspan="3">13.6 ± 0.1</td><td>Si II</td><td>15.72 ± 0.01</td></tr><tr><td>Al III</td><td>12.77 ± 0.01</td></tr><tr><td>Ni II</td><td>12.88 ± 0.01</td></tr><tr><td rowspan="3">4</td><td rowspan="3">3.326 26</td><td rowspan="3">2.0 ± 0.1</td><td>S II</td><td>14.83 ± 0.01</td></tr><tr><td>Si II</td><td>15.20 ± 0.01</td></tr><tr><td>Al III</td><td>11.96 ± 0.01</td></tr><tr><td rowspan="3">5</td><td rowspan="3">3.326 63</td><td rowspan="3">10.7 ± 0.2</td><td>Ni II</td><td>12.27 ± 0.02</td></tr><tr><td>S II</td><td>14.16 ± 0.02</td></tr><tr><td>Si II</td><td>13.96 ± 0.03</td></tr><tr><td rowspan="3">6</td><td rowspan="3">3.327 00</td><td rowspan="3">11.6 ± 0.1</td><td>Al III</td><td>11.55 ± 0.04</td></tr><tr><td>Ni II</td><td>12.48 ± 0.01</td></tr><tr><td>S II</td><td>14.27 ± 0.01</td></tr><tr><td rowspan="3">7</td><td rowspan="3">3.327 97</td><td rowspan="3">13.2 ± 0.1</td><td>Si II</td><td>14.55 ± 0.01</td></tr><tr><td>Al III</td><td>11.94 ± 0.02</td></tr><tr><td>Ni II</td><td>12.71 ± 0.01</td></tr><tr><td rowspan="3">1</td><td rowspan="3">3.325 00</td><td rowspan="3">10</td><td>S II</td><td>14.25 ± 0.01</td></tr><tr><td>Si II</td><td>14.57 ± 0.01</td></tr><tr><td>Al III</td><td>12.12 ± 0.01</td></tr><tr><td rowspan="3">2</td><td rowspan="3">3.325 58</td><td rowspan="3">20</td><td>Ni II</td><td>12.93 ± 0.01</td></tr><tr><td>S II</td><td>14.45 ± 0.01</td></tr><tr><td>Si II</td><td>14.89 ± 0.01</td></tr><tr><td rowspan="3">3</td><td rowspan="3">3.327 55</td><td rowspan="3">7</td><td>Al III</td><td>12.60 ± 0.01</td></tr><tr><td>C IV</td><td>12.9 ± 0.02</td></tr><tr><td>Si IV</td><td>13.00 ± 0.01</td></tr><tr><td rowspan="2">1</td><td rowspan="2">3.325 00</td><td rowspan="2">10</td><td>C IV</td><td>13.48 ± 0.02</td></tr><tr><td>Si IV</td><td>13.40 ± 0.01</td></tr><tr><td rowspan="2">2</td><td rowspan="2">3.325 58</td><td rowspan="2">20</td><td>C IV</td><td>13.10 ± 0.01</td></tr><tr><td>Si IV</td><td>12.00 ± 0.02</td></tr></tbody></table>

$\log N(Fe II) = 15.06 \pm 0.04$, $\log N(Cr II) = 13.38 \pm 0.03$, $\log N(Ni II) = 13.80 \pm 0.03$, $\log N(Zn II) = 12.69 \pm 0.02$ and $\log N(Al III) = 13.18 \pm 0.03$. For $S II \lambda \lambda 1250$ and 1253, a blend in the blue part of the absorption prevent from fitting the full profile. However, a lower limit is derived from the fit of the strong component in the red based on the other elements. The resulting column density is $\log N(S II) > 14.90$.

The spectrum cover several high-ionization ions: C IV $\lambda \lambda 1550$, 1548 and Si IV $\lambda \lambda 1393$ and 1402. However, no satisfactory fit could

be found for the C IV doublet because of the low SNR in this portion of the spectrum. On the contrary, a four-component profile is derived for the Si IV $\lambda 1402$. It is also interesting to note that the velocity components are quite similar to the low-ionization ions components. The Si IV $\lambda 1393$ line suffers from a blend and again a limited SNR, so that the fit is performed with fix parameters but for the second Doppler-parameter. This fit results in $\log N(Si IV) = 14.2 \pm 0.01$.

The parameter fits of the individual components are listed in Table C21 and the corresponding Voigt profile fits are shown in Fig. C21.

$$ \begin{array}{l} \text{C22 QSO B2318-1107 } z_{\text{em}} = 2.96, z_{\text{abs}} = 1.629, \\ \log N(\text{HI}) = 20.52 \pm 0.14 \end{array} $$

A broad variety of ions are covered in the EUADP spectrum of this low-redshift absorber. The low-ionization ions detected are Fe II $\lambda \lambda \lambda 2260$, 22492374, Mn II $\lambda 2576$, Al II $\lambda 1670$, C II $\lambda 1334$, Si II $\lambda \lambda \lambda 1260$, 1304 and 1526. The profile of the C II line appears to be saturated and blended from a comparison with other low-ionization ions. This line is therefore not considered for a fit. Likewise, the Si II lines are saturated and are not fitted. The Al II $\lambda 1670$ line appears to be blended (strong absorption on the blue side of the line), and therefore only an upper limit is available: $\log N(Al II) < 14.93$. Fe II and Mn II are well fitted with 2 components (from the asymmetry of Fe II $\lambda 2249$): resulting in $\log N(Fe II) = 14.14 \pm 0.02$ and $\log N(Mn II) = 11.78 \pm 0.04$. Also, we derive upper limits from non detection of S II $\lambda 1250$, $\log N(S II) < 14.54$, Cr II $\lambda 2062$, $\log N(Cr II) < 12.47$, Zn II $\lambda 2026$, $\log N(Zn II) < 11.74$, Mg I $\lambda 2026$ and $\log N(Mg I) < 12.37$.

The detected intermediate-ionization transitions are Al III $\lambda \lambda 1854$ and 1862. The absorption profiles differ significantly from the high- or the low-ionization ions (red component stronger than the blue one). The fit is thus performed separately with two components. The resulting column density is $\log N(Al III) = 12.17 \pm 0.02$.

The high-ionization ions detected are Si IV $\lambda \lambda 1393$, 1402 and C IV $\lambda \lambda 1548$ (saturated) and 1550. The position of the Si IV lines (on the red wing of the Ly a absorber for $\lambda 1393$ and blended from the forest for $\lambda 1402$) prevents a robust fit for the Si IV lines. Similarly to the low-ionization ions, the asymmetry of C IV $\lambda 1550$ suggests a two-component profile. We derive an upper limit for C IV from a two-component fit of C IV $\lambda 1550$, as the saturated C IV $\lambda 1548$ brings no constraints on possible contamination of C IV $\lambda 1550$. We obtain $\log N(C IV) < 14.10$.

The parameter fits of the individual components are listed in Table C22 and the corresponding Voigt profile fits are shown in Fig. C22.
<figure><img src="image_27.png" /><figcaption>Figure C12. QSOJ115538.6+053050 $z = 3.32$.</figcaption></figure>

<table><caption>**Table C13.** Voigt profile fit parameters to the low-ionization species for the $z_{abs} = 1.72$ log N(HI) = 19.48 ± 0.13 absorber towards QSO LBQS 1232+0815.</caption><thead><tr><th>Comp.</th><th>z<sub>abs</sub></th><th>b<br>km s<sup>-1</sup></th><th>Ion</th><th>log N<br>cm<sup>-2</sup></th></tr></thead><tbody><tr><td rowspan="3">1</td><td rowspan="3">1.71942</td><td rowspan="3">7.7 ± 0.1</td><td>Fe II</td><td>13.17 ± 0.01</td></tr><tr><td>Al III</td><td>12.61 ± 0.01</td></tr><tr><td>Si II</td><td>14.10 ± 0.01</td></tr><tr><td rowspan="3">2</td><td rowspan="3">1.71958</td><td rowspan="3">4.6 ± 0.4</td><td>Fe II</td><td>12.15 ± 0.02</td></tr><tr><td>Al III</td><td>11.96 ± 0.02</td></tr><tr><td>Si II</td><td>13.20 ± 0.02</td></tr><tr><td rowspan="3">3</td><td rowspan="3">1.71995</td><td rowspan="3">8.2 ± 0.6</td><td>Fe II</td><td>12.07 ± 0.03</td></tr><tr><td>Al III</td><td>12.04 ± 0.02</td></tr><tr><td>Si II</td><td>13.06 ± 0.02</td></tr><tr><td rowspan="3">4</td><td rowspan="3">1.72014</td><td rowspan="3">8.8 ± 0.1</td><td>Fe II</td><td>13.02 ± 0.01</td></tr><tr><td>Al III</td><td>12.90</td></tr><tr><td>Si II</td><td>14.01 ± 0.01</td></tr><tr><td rowspan="3">5</td><td rowspan="3">1.72036</td><td rowspan="3">7.1 ± 0.3</td><td>Fe II</td><td>12.16 ± 0.02</td></tr><tr><td>Al III</td><td>12.37 ± 0.01</td></tr><tr><td>Si II</td><td>—</td></tr><tr><td rowspan="3">6</td><td rowspan="3">1.72094</td><td rowspan="3">18.3 ± 0.6</td><td>Fe II</td><td>12.33 ± 0.02</td></tr><tr><td>Al III</td><td>12.41 ± 0.01</td></tr><tr><td>Si II</td><td>—</td></tr><tr><td>1</td><td>1.71946</td><td>23.3 ± 0.3</td><td>Si IV</td><td>13.47 ± 0.01</td></tr><tr><td>2</td><td>1.72008</td><td>14.5 ± 0.5</td><td>Si IV</td><td>>14.50</td></tr><tr><td>3</td><td>1.72032</td><td>14.2 ± 0.5</td><td>Si IV</td><td>>13.82</td></tr><tr><td>4</td><td>1.72089</td><td>10.5 ± 0.3</td><td>Si IV</td><td>13.49 ± 0.01</td></tr><tr><td>5</td><td>1.72104</td><td>27.8 ± 0.6</td><td>Si IV</td><td>13.41 ± 0.01</td></tr></tbody></table>
<figure><img src="image_28.png" /><figcaption>Figure C13. QSOLBQS1232+0815.</figcaption></figure>

<table><caption>**Table C14.** Voigt profile fit parameters to the low- and intermediate-ionization species for the $z_{abs} = 2.654 \log N(HI) = 19.56 \pm 0.13$ absorber towards QSO J1330-2522.</caption><thead><tr><th>Comp.</th><th>z<sub>abs</sub></th><th>b<br>km s<sup>-1</sup></th><th>Ion</th><th>log N<br>cm<sup>-2</sup></th></tr></thead><tbody><tr><td rowspan="2">1</td><td rowspan="2">2.654 14</td><td rowspan="2">6.7</td><td>Al II</td><td>12.16 ± 0.02</td></tr><tr><td>Al III</td><td>12.55 ± 0.02</td></tr><tr><td rowspan="2">2</td><td rowspan="2">2.654 33</td><td rowspan="2">2.0</td><td>Al II</td><td>10.90 ± 0.21</td></tr><tr><td>Al III</td><td>11.79 ± 0.08</td></tr></tbody></table>
<figure><img src="image_29.png" /><figcaption>Figure C14. QSOJ1330-2522 z = 2.654</figcaption></figure>

<table><caption>**Table C15.** Voigt profile fit parameters to the low-ionization species for the $z_{abs}$ = 2.397 log N(HI) = 19.85 ± 0.08 absorber towards QSO J1356-1101.</caption><thead><tr><th>Comp.</th><th>z<sub>abs</sub></th><th>b<br>km s<sup>-1</sup></th><th>Ion</th><th>log N<br>cm<sup>-2</sup></th></tr></thead><tbody><tr><td>1</td><td>2.393 39</td><td>11.0 ± 0.3</td><td>Fe II</td><td>12.81 ± 0.01</td></tr><tr><td>2</td><td>2.396 21</td><td>14.8 ± 1.4</td><td>Fe II</td><td>11.99 ± 0.08</td></tr><tr><td>3</td><td>2.396 29</td><td>4.5 ± 0.3</td><td>Fe II</td><td>12.44 ± 0.02</td></tr><tr><td>4</td><td>2.396 69</td><td>61.1 ± 5.4</td><td>Fe II</td><td>12.63 ± 0.04</td></tr><tr><td>5</td><td>2.396 77</td><td>5.8 ± 0.1</td><td>Fe II</td><td>12.95 ± 0.01</td></tr><tr><td>6</td><td>2.397 06</td><td>2.4 ± 0.3</td><td>Fe II</td><td>12.44 ± 0.02</td></tr><tr><td>7</td><td>2.397 14</td><td>2.6 ± 0.6</td><td>Fe II</td><td>12.10 ± 0.02</td></tr></tbody></table>
<figure><img src="image_30.png" /><figcaption>Figure C15. QSOJ1356-1101.</figcaption></figure>
<table><caption>**Table C16.** Voigt profile fit parameters to the low- and high-ionization species for the $z_{abs} = 3.104 \log N(H\text{i}) = 19.7 \pm 0.20$ absorber towards QSO J1621-0042.</caption><thead><tr><th>Comp.</th><th>z<sub>abs</sub></th><th>b<br>km s<sup>-1</sup></th><th>Ion</th><th>log N<br>cm<sup>-2</sup></th><th>Comp.</th><th>z<sub>abs</sub></th><th>b<br>km s<sup>-1</sup></th><th>Ion</th><th>log N<br>cm<sup>-2</sup></th></tr></thead><tbody><tr><td rowspan="3">1</td><td rowspan="3">3.10394</td><td rowspan="3">3.7 ± 0.7</td><td>Fe II</td><td>12.62 ± 0.06</td><td rowspan="3">1</td><td>3.10509</td><td>7.0 ± 1.0</td><td>Si IV</td><td>12.77 ± 0.07</td></tr><tr><td>Si II</td><td>12.95 ± 0.03</td><td>3.10541</td><td>24.6 ± 1.0</td><td>C IV</td><td>13.49 ± 0.21</td></tr><tr><td>C II</td><td>13.90 ± 0.03</td><td>3.10530</td><td>7.9 ± 3</td><td>Si IV</td><td>12.69 ± 0.18</td></tr><tr><td rowspan="3">2</td><td rowspan="3">3.10407</td><td rowspan="3">2.7 ± 0.5</td><td>Fe II</td><td>13.03 ± 0.04</td><td rowspan="3">3</td><td>3.10539</td><td>6.4 ± 3.4</td><td>C IV</td><td>12.13 ± 0.21</td></tr><tr><td>Si II</td><td>13.55 ± 0.03</td><td>3.10564</td><td>12.0 ± 2.8</td><td>Si IV</td><td>13.47 ± 0.09</td></tr><tr><td>C II</td><td>14.00 ± 0.17</td><td>3.10568</td><td>8.5 ± 1.0</td><td>C IV</td><td>13.16 ± 0.05</td></tr><tr><td rowspan="3">3</td><td rowspan="3">3.10415</td><td rowspan="3">8.4 ± 2</td><td>Fe II</td><td>12.32 ± 0.19</td><td rowspan="3">4</td><td>3.10588</td><td>6.1 ± 1.9</td><td>Si IV</td><td>13.40 ± 0.12</td></tr><tr><td>Si II</td><td>12.93 ± 0.15</td><td>3.10592</td><td>9.0 ± 0.6</td><td>C IV</td><td>13.64 ± 0.04</td></tr><tr><td>C II</td><td>13.57 ± 0.02</td><td>3.10607</td><td>7.5 ± 1.7</td><td>Si IV</td><td>13.52 ± 0.09</td></tr><tr><td rowspan="3">4</td><td rowspan="3">3.10438</td><td rowspan="3">6.0 ± 1.1</td><td>Fe II</td><td>12.28 ± 0.11</td><td rowspan="3">5</td><td>3.10612</td><td>7.9 ± 0.6</td><td>C IV</td><td>13.69 ± 0.05</td></tr><tr><td>Si II</td><td>12.73 ± 0.06</td><td>3.10631</td><td>8.1 ± 1.5</td><td>Si IV</td><td>13.16 ± 0.10</td></tr><tr><td>C II</td><td>13.47 ± 0.01</td><td>3.10632</td><td>8.6 ± 0.5</td><td>C IV</td><td>13.36 ± 0.05</td></tr><tr><td rowspan="3">5</td><td rowspan="3">3.10462</td><td rowspan="3">7.3 ± 1.4</td><td>Fe II</td><td>11.95 ± 0.21</td><td rowspan="3">7</td><td>3.10657</td><td>15.0 ± 1.6</td><td>Si IV</td><td>13.10 ± 0.06</td></tr><tr><td>Si II</td><td>12.37 ± 0.06</td><td>3.10659</td><td>21.5 ± 0.7</td><td>C IV</td><td>13.70 ± 0.02</td></tr><tr><td>C II</td><td>13.00 ± 0.01</td><td>3.10709</td><td>9.3 ± 1.2</td><td>Si IV</td><td>12.51 ± 0.04</td></tr><tr><td rowspan="3">6</td><td rowspan="3">3.10523</td><td rowspan="3">6.1 ± 0.13</td><td>Fe II</td><td>13.28 ± 0.01</td><td rowspan="3">9</td><td>3.10712</td><td>12.1 ± 0.4</td><td>C IV</td><td>13.24 ± 0.02</td></tr><tr><td>Si II</td><td>13.74 ± 0.01</td><td>3.10742</td><td>7.9 ± 1.1</td><td>Si IV</td><td>12.40 ± 0.04</td></tr><tr><td>C II</td><td>—</td><td>3.10746</td><td>9.3 ± 0.4</td><td>C IV</td><td>12.95 ± 0.02</td></tr><tr><td rowspan="3">7</td><td rowspan="3">3.10563</td><td rowspan="3">7.9 ± 0.23</td><td>Fe II</td><td>13.16 ± 0.02</td><td rowspan="3">10</td><td>3.10780</td><td>6.0 ± 0.6</td><td>Si IV</td><td>12.50 ± 0.02</td></tr><tr><td>Si II</td><td>13.73 ± 0.03</td><td>3.10785</td><td>12.2 ± 0.2</td><td>C IV</td><td>13.27 ± 0.01</td></tr><tr><td>C II</td><td>—</td><td>3.10836</td><td>6.5 ± 0.7</td><td>Si IV</td><td>12.61 ± 0.03</td></tr><tr><td rowspan="3">8</td><td rowspan="3">3.10593</td><td rowspan="3">20.0 ± 1.08</td><td>Fe II</td><td>13.07 ± 0.05</td><td rowspan="3">12</td><td>3.10842</td><td>10.4 ± 0.2</td><td>C IV</td><td>13.63 ± 0.01</td></tr><tr><td>Si II</td><td>13.73 ± 0.03</td><td>3.10859</td><td>5.7 ± 1.2</td><td>Si IV</td><td>12.49 ± 0.07</td></tr><tr><td>C II</td><td>—</td><td>3.10865</td><td>5.5 ± 0.3</td><td>C IV</td><td>13.43 ± 0.02</td></tr><tr><td rowspan="3">9</td><td rowspan="3">3.10601</td><td rowspan="3">5.0</td><td>Fe II</td><td>13.10 ± 0.02</td><td rowspan="3">13</td><td>3.10883</td><td>10.6 ± 2.1</td><td>Si IV</td><td>12.53 ± 0.07</td></tr><tr><td>Si II</td><td>13.66 ± 0.02</td><td>3.10887</td><td>10.4 ± 0.3</td><td>C IV</td><td>13.76 ± 0.01</td></tr><tr><td>C II</td><td>—</td><td>3.10922</td><td>7.5 ± 0.3</td><td>Si IV</td><td>13.47 ± 0.03</td></tr><tr><td rowspan="3">10</td><td rowspan="3">3.10618</td><td rowspan="3">0.9 ± 0.2</td><td>Fe II</td><td>—</td><td rowspan="3">14</td><td>3.10928</td><td>14.1 ± 0.1</td><td>C IV</td><td>14.12 ± 0.01</td></tr><tr><td>Si II</td><td>13.39 ± 0.25</td><td></td><td></td><td></td><td></td></tr><tr><td>C II</td><td>—</td><td></td><td></td><td></td><td></td></tr><tr><td rowspan="3">11</td><td rowspan="3">3.10743</td><td rowspan="3">6.1 ± 0.29</td><td>Fe II</td><td>12.47 ± 0.06</td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Si II</td><td>12.93 ± 0.01</td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>C II</td><td>—</td><td></td><td></td><td></td><td></td><td></td></tr><tr><td rowspan="3">12</td><td rowspan="3">3.10926</td><td rowspan="3">2.5 ± 0.25</td><td>Fe II</td><td>10.84 ± 1.99</td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Si II</td><td>12.77 ± 0.01</td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>C II</td><td>—</td><td></td><td></td><td></td><td></td><td></td></tr></tbody></table>
<figure><img src="image_31.png" /><figcaption>Figure C16. QSOJ1621-0042.</figcaption></figure>

<table><caption>**Table C17.** Voigt profile fit parameters to the low-ionization species for the $z_{abs} = 0.531$ log N(HI) = 20.7 ± 0.09 absorber towards QSO 4C 12.59.</caption><thead><tr><th>Comp.</th><th>z<sub>abs</sub></th><th>b<br>km s<sup>-1</sup></th><th>Ion</th><th>log N<br>cm<sup>-2</sup></th></tr></thead><tbody><tr><td>1</td><td>0.531 23</td><td>7.0 ± 1.3</td><td>Fe II</td><td>13.20 ± 0.08</td></tr><tr><td>2</td><td>0.531 30</td><td>4.6 ± 1.4</td><td>Fe II</td><td>13.58 ± 0.08</td></tr><tr><td>3</td><td>0.531 35</td><td>4.0 ± 1.1</td><td>Fe II</td><td>13.68 ± 0.10</td></tr><tr><td>4</td><td>0.531 43</td><td>13.9 ± 4.1</td><td>Fe II</td><td>13.59 ± 0.26</td></tr><tr><td>5</td><td>0.531 43</td><td>6.8 ± 1.4</td><td>Fe II</td><td>13.47 ± 0.28</td></tr><tr><td>6</td><td>0.531 56</td><td>6.3 ± 1.8</td><td>Fe II</td><td>13.06 ± 0.12</td></tr></tbody></table>
<figure><img src="image_32.png" /><figcaption>Figure C17. QSO4C12.59.</figcaption></figure>
<table><caption>**Table C18.** Voigt profile fit parameters to the low- and high-ionization species for the $z_{abs}$ = 1.912 log N(HI) = 19.5 ± 0.10 absorber towards QSO LBQS 2114-4347.</caption><thead><tr><th>Comp.</th><th>z<sub>abs</sub></th><th>b<br>km s<sup>-1</sup></th><th>Ion</th><th>log N<br>cm<sup>-2</sup></th></tr></thead><tbody><tr><td rowspan="3">1</td><td rowspan="3">1.910 9296</td><td rowspan="3">6.7 ± 0.1</td><td>Si II</td><td>13.16 ± 0.03</td></tr><tr><td>Fe II</td><td>12.65 ± 0.01</td></tr><tr><td>Al II</td><td>11.70 ± 0.02</td></tr><tr><td rowspan="3">2</td><td rowspan="3">1.911 1506</td><td rowspan="3">3.0 ± 0.1</td><td>Mg II</td><td>12.92 ± 0.01</td></tr><tr><td>Si II</td><td>12.53 ± 0.01</td></tr><tr><td>Fe II</td><td>12.11 ± 0.01</td></tr><tr><td rowspan="3">3</td><td rowspan="3">1.911 3052</td><td rowspan="3">4.6 ± 0.1</td><td>Al II</td><td>10.84 ± 0.01</td></tr><tr><td>Mg II</td><td>11.76 ± 0.01</td></tr><tr><td>Si II</td><td>13.44 ± 0.01</td></tr><tr><td rowspan="3">4</td><td rowspan="3">1.911 46</td><td rowspan="3">12.3 ± 0.1</td><td>Fe II</td><td>13.18 ± 0.01</td></tr><tr><td>Al II</td><td>12.10 ± 0.01</td></tr><tr><td>Mg II</td><td>13.23 ± 0.01</td></tr><tr><td rowspan="3">5</td><td rowspan="3">1.911 48</td><td rowspan="3">3.7 ± 0.1</td><td>Si II</td><td>12.96 ± 0.01</td></tr><tr><td>Fe II</td><td>—</td></tr><tr><td>Al II</td><td>11.66 ± 0.01</td></tr><tr><td rowspan="3">6</td><td rowspan="3">1.911 65</td><td rowspan="3">5.5 ± 0.1</td><td>Mg II</td><td>12.53 ± 0.01</td></tr><tr><td>Si II</td><td>12.79 ± 0.04</td></tr><tr><td>Fe II</td><td>12.38 ± 0.01</td></tr><tr><td rowspan="3">7</td><td rowspan="3">1.911 85</td><td rowspan="3">4.1 ± 0.1</td><td>Al II</td><td>11.75 ± 0.01</td></tr><tr><td>Mg II</td><td>12.69 ± 0.01</td></tr><tr><td>Si II</td><td>13.00 ± 0.03</td></tr><tr><td rowspan="3">8</td><td rowspan="3">1.912 05</td><td rowspan="3">6.7 ± 0.1</td><td>Fe II</td><td>12.30 ± 0.01</td></tr><tr><td>Al II</td><td>11.43 ± 0.02</td></tr><tr><td>Mg II</td><td>12.55 ± 0.01</td></tr><tr><td rowspan="3">9</td><td rowspan="3">1.912 21</td><td rowspan="3">4.0 ± 1.0</td><td>Si II</td><td>14.08 ± 0.02</td></tr><tr><td>Fe II</td><td>13.77 ± 0.01</td></tr><tr><td>Al II</td><td>12.69 ± 0.01</td></tr><tr><td rowspan="3">10</td><td rowspan="3">1.912 32</td><td rowspan="3">0.9 ± 0.1</td><td>Mg II</td><td>14.21 ± 0.01</td></tr><tr><td>Si II</td><td>13.37 ± 0.20</td></tr><tr><td>Fe II</td><td>12.88 ± 0.01</td></tr><tr><td rowspan="3">11</td><td rowspan="3">1.912 52</td><td rowspan="3">6.3 ± 1.0</td><td>Al II</td><td>11.73 ± 0.01</td></tr><tr><td>Mg II</td><td>13.12 ± 0.01</td></tr><tr><td>Si II</td><td>13.17 ± 0.02</td></tr><tr><td rowspan="3">12</td><td rowspan="3">1.912 73</td><td rowspan="3">16.3 ± 0.3</td><td>Fe II</td><td>12.59 ± 0.01</td></tr><tr><td>Al II</td><td>11.81 ± 0.01</td></tr><tr><td>Mg II</td><td>13.14 ± 0.01</td></tr><tr><td rowspan="3">13</td><td rowspan="3">1.911 99</td><td rowspan="3">8.5 ± 0.3</td><td>Si II</td><td>12.25 ± 0.01</td></tr><tr><td>Fe II</td><td>12.41 ± 0.01</td></tr><tr><td>Al II</td><td>10.91 ± 0.01</td></tr><tr><td rowspan="3">14</td><td rowspan="3">1.912 24</td><td rowspan="3">12.3 ± 0.8</td><td>Mg II</td><td>13.08 ± 0.01</td></tr><tr><td>Si II</td><td>13.24 ± 0.02</td></tr><tr><td>Fe II</td><td>12.78 ± 0.01</td></tr><tr><td rowspan="3">15</td><td rowspan="3">1.912 52</td><td rowspan="3">8.8 ± 0.2</td><td>Al II</td><td>11.84 ± 0.01</td></tr><tr><td>Mg II</td><td>13.05 ± 0.01</td></tr><tr><td>Si IV</td><td>14.19 ± 0.01</td></tr><tr><td rowspan="2">16</td><td rowspan="2">1.911 73</td><td rowspan="2">16.3 ± 0.3</td><td>Si IV</td><td>12.97 ± 0.01</td></tr><tr><td>Al IV</td><td>13.63 ± 0.02</td></tr><tr><td rowspan="2">17</td><td rowspan="2">1.911 99</td><td rowspan="2">8.5 ± 0.3</td><td>Si IV</td><td>12.65 ± 0.02</td></tr><tr><td>Al IV</td><td>13.18 ± 0.03</td></tr><tr><td rowspan="2">18</td><td rowspan="2">1.912 24</td><td rowspan="2">12.3 ± 0.8</td><td>Si IV</td><td>12.63 ± 0.02</td></tr><tr><td>Al IV</td><td>13.49 ± 0.01</td></tr><tr><td rowspan="2">19</td><td rowspan="2">1.912 52</td><td rowspan="2">8.8 ± 0.2</td><td>Si IV</td><td>12.97 ± 0.01</td></tr><tr><td>Al IV</td><td>13.05 ± 0.01</td></tr></tbody></table>
<figure><img src="image_33.png" /><figcaption>Figure C18. QSOLBQS2114-4347.</figcaption></figure>

<table><caption>Table C19. Voigt profile fit parameters to the low- and intermediate-ionization species for the $z_{abs} = 2.638 \log N(H_i) = 19.25 \pm 0.15$ absorber towards QSO B2126-15.</caption><thead><tr><th>Comp.</th><th>z<sub>abs</sub></th><th>b<br>km s<sup>-1</sup></th><th>Ion</th><th>log N<br>cm<sup>-2</sup></th></tr></thead><tbody><tr><td rowspan="3">1</td><td rowspan="3">2.637 67</td><td rowspan="3">17.8 ± 0.1</td><td>Fe II</td><td>13.77 ± 0.01</td></tr><tr><td>Si II</td><td>14.38 ± 0.02</td></tr><tr><td>Ni II</td><td>12.66 ± 0.02</td></tr><tr><td rowspan="3">2</td><td rowspan="3">2.637 99</td><td rowspan="3">4.1 ± 0.1</td><td>Fe II</td><td>13.39 ± 0.01</td></tr><tr><td>Si II</td><td>13.80 ± 0.05</td></tr><tr><td>Ni II</td><td>12.47 ± 0.01</td></tr><tr><td rowspan="3">3</td><td rowspan="3">2.638 07</td><td rowspan="3">19.3 ± 0.3</td><td>Fe II</td><td>13.45 ± 0.01</td></tr><tr><td>Si II</td><td>14.21 ± 0.03</td></tr><tr><td>Ni II</td><td>12.83 ± 0.02</td></tr><tr><td>1</td><td>2.637 58</td><td>9.9 ± 0.5</td><td>Al III</td><td>12.38 ± 0.02</td></tr><tr><td>2</td><td>2.637 84</td><td>13.3 ± 0.2</td><td>Al III</td><td>12.84 ± 0.01</td></tr><tr><td>3</td><td>2.638 02</td><td>4.2 ± 0.5</td><td>Al III</td><td>12.34 ± 0.05</td></tr><tr><td>4</td><td>2.638 18</td><td>10.3 ± 0.8</td><td>Al III</td><td>12.52 ± 0.08</td></tr><tr><td>5</td><td>2.638 27</td><td>11.75 ± 1.8</td><td>Al III</td><td>12.43 ± 0.11</td></tr></tbody></table>
<figure><img src="image_34.png" /><figcaption>Figure C19. QSOB2126-15 $z_{abs}$ = 2.638.</figcaption></figure>
<table><caption>**Table C20.** Voigt profile fit parameters to the low- and high- and intermediate-ionization species for the $z_{abs} = 2.769 \log N(H_i) = 19.20 \pm 0.15$ absorber towards QSO B2126-15.</caption><thead><tr><th>Comp.</th><th>z<sub>abs</sub></th><th>b<br>km s<sup>-1</sup></th><th>Ion</th><th>log N<br>cm<sup>-2</sup></th></tr></thead><tbody><tr><td rowspan="3">1</td><td rowspan="3">2.76751</td><td rowspan="3">9.4 ± 0.8</td><td>Fe II</td><td>12.78 ± 0.01</td></tr><tr><td>Si II</td><td>13.52 ± 0.01</td></tr><tr><td>Al II</td><td>12.40 ± 0.01</td></tr><tr><td rowspan="3">2</td><td rowspan="3">2.76768</td><td rowspan="3">4.4 ± 0.1</td><td>Fe II</td><td>13.23 ± 0.01</td></tr><tr><td>Si II</td><td>13.70 ± 0.01</td></tr><tr><td>Al II</td><td>13.07 ± 0.01</td></tr><tr><td rowspan="3">3</td><td rowspan="3">2.76793</td><td rowspan="3">2.1 ± 0.2</td><td>Fe II</td><td>13.06 ± 0.01</td></tr><tr><td>Si II</td><td>13.64 ± 0.07</td></tr><tr><td>Al II</td><td>13.42 ± 0.01</td></tr><tr><td rowspan="3">4</td><td rowspan="3">2.76808</td><td rowspan="3">3.7 ± 1.4</td><td>Fe II</td><td>11.91 ± 0.05</td></tr><tr><td>Si II</td><td>12.87 ± 0.01</td></tr><tr><td>Al II</td><td>11.58 ± 0.01</td></tr><tr><td rowspan="3">5</td><td rowspan="3">2.76835</td><td rowspan="3">6.2 ± 0.2</td><td>Fe II</td><td>13.19 ± 0.01</td></tr><tr><td>Si II</td><td>13.94 ± 0.05</td></tr><tr><td>Al II</td><td>12.65 ± 0.01</td></tr><tr><td rowspan="3">6</td><td rowspan="3">2.76855</td><td rowspan="3">7 ± 0.2</td><td>Fe II</td><td>13.67 ± 0.01</td></tr><tr><td>Si II</td><td>14.30 ± 0.02</td></tr><tr><td>Al II</td><td>13.13 ± 0.01</td></tr><tr><td rowspan="3">7</td><td rowspan="3">2.76879</td><td rowspan="3">6.8 ± 0.1</td><td>Fe II</td><td>13.54 ± 0.01</td></tr><tr><td>Si II</td><td>14.15 ± 0.03</td></tr><tr><td>Al II</td><td>13.70 ± 0.01</td></tr><tr><td rowspan="3">8</td><td rowspan="3">2.76913</td><td rowspan="3">3.2 ± 0.2</td><td>Fe II</td><td>12.99 ± 0.01</td></tr><tr><td>Si II</td><td>13.55 ± 0.09</td></tr><tr><td>Al II</td><td>12.45 ± 0.01</td></tr><tr><td rowspan="3">9</td><td rowspan="3">2.76949</td><td rowspan="3">4.4 ± 0.3</td><td>Fe II</td><td>12.65 ± 0.01</td></tr><tr><td>Si II</td><td>13.26 ± 0.01</td></tr><tr><td>Al II</td><td>12.10 ± 0.01</td></tr><tr><td rowspan="2">1</td><td rowspan="2">2.76751</td><td rowspan="2">4.9 ± 0.9</td><td>Si IV</td><td>12.55 ± 0.06</td></tr><tr><td>Al III</td><td>11.91 ± 0.02</td></tr><tr><td rowspan="2">2</td><td rowspan="2">2.76775</td><td rowspan="2">26.3 ± 2.5</td><td>Si IV</td><td>13.02 ± 0.04</td></tr><tr><td>Al III</td><td>12.33 ± 0.01</td></tr><tr><td rowspan="2">3</td><td rowspan="2">2.76816</td><td rowspan="2">7.3 ± 6.9</td><td>Si IV</td><td>12.37 ± 0.47</td></tr><tr><td>Al III</td><td>11.02 ± 0.11</td></tr><tr><td rowspan="2">4</td><td rowspan="2">2.76841</td><td rowspan="2">4.6 ± 2.9</td><td>Si IV</td><td>13.17 ± 0.38</td></tr><tr><td>Al III</td><td>12.01 ± 0.02</td></tr><tr><td rowspan="2">5</td><td rowspan="2">2.76851</td><td rowspan="2">12.0 ± 6.2</td><td>Si IV</td><td>13.18 ± 0.46</td></tr><tr><td>Al III</td><td>12.72 ± 0.01</td></tr><tr><td rowspan="2">6</td><td rowspan="2">2.76882</td><td rowspan="2">9.1 ± 1.7</td><td>Si IV</td><td>13.02 ± 0.10</td></tr><tr><td>Al III</td><td>12.32 ± 0.01</td></tr><tr><td rowspan="2">7</td><td rowspan="2">2.76907</td><td rowspan="2">12.4 ± 4.3</td><td>Si IV</td><td>12.88 ± 0.15</td></tr><tr><td>Al III</td><td>11.87 ± 0.02</td></tr><tr><td rowspan="2">8</td><td rowspan="2">2.76933</td><td rowspan="2">4.7 ± 3.9</td><td>Si IV</td><td>12.30 ± 0.36</td></tr><tr><td>Al III</td><td>10.70 ± 0.21</td></tr><tr><td rowspan="2">9</td><td rowspan="2">2.76947</td><td rowspan="2">7.0 ± 2.6</td><td>Si IV</td><td>12.47 ± 0.18</td></tr><tr><td>Al III</td><td>11.85 ± 0.02</td></tr></tbody></table>
<figure><img src="image_35.png" /><figcaption>Figure C20. QSOB2126-15 $z = 2.769$.</figcaption></figure>