The ESO UVES Advanced Data Products Quasar Sample - VI. Sub-Damped
  Lyman-$\alpha$ Metallicity Measurements and the Circum-Galactic Medium
  The Circum-Galactic 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-$\alpha$
absorbers (sub-DLAs, defined as absorbers with 19.0 < log N(H I) < 20.3) with
redshift 0.584 < $\rm z_{abs}$ < 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 modeled
Voigt profile features. The correlation between the velocity width delta_V90 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.
