Abstract
We study metal depletion due to dust in the interstellar medium (ISM) to
infer the properties of dust grains and characterize the metal and dust content
of galaxies, down to low metallicity and intermediate redshift z. We provide
metal column densities and abundances of a sample of 70 damped Lyman-\alpha
absorbers (DLAs) towards quasars, observed at high spectral resolution with the
Very Large Telescope (VLT) Ultraviolet and Visual Echelle Spectrograph (UVES).
This is the largest sample of phosphorus abundances measured in DLAs so far. We
use literature measurements for Galactic clouds to cover the high-metallicity
end. We discover tight (scatter <= 0.2 dex) correlations between Zn/Fe and
the observed relative abundances, which are due to dust depletion. This implies
that grain-growth in the ISM is an important process of dust production. These
sequences are continuous in Zn/Fe from dust-free to dusty DLAs, and to
Galactic clouds, suggesting that the availability of refractory metals in the
ISM is crucial for dust production, regardless of the star-formation history.
We observe S/Zn up to ~ 0.25 dex in DLAs, broadly consistent with Galactic
stellar abundances. Furthermore, we find a good agreement between the
nucleosynthetic pattern of Galactic halo stars and our observations of the
least dusty DLAs. This supports recent star formation in low-metallicity DLAs.
The derived depletions of Zn, O, P, S, Si, Mg, Mn, Cr, and Fe correlate with
Zn/Fe, with steeper slopes for more refractory elements. P is mostly not
affected by dust depletion. We present canonical depletion patterns, to be used
as reference in future studies of relative abundances and depletion. We derive
the total (dust-corrected) metallicity, typically -2 <= M/Htot <= 0 for DLAs,
and scattered around solar metallicity for the Galactic ISM. The dust-to-metals
ratio increases with metallicity... abridged
Description
[1608.08621] Dust-depletion sequences in damped Lyman-{\alpha} absorbers: a unified picture from low-metallicity systems to the Galaxy
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