The high A_V Quasar Survey: A z=2.027 metal-rich damped Lyman-alpha absorber towards a red quasar at z=3.21

Abstract

To fully exploit the potential of quasars as probes of cosmic chemical evolution and the internal gas dynamics of galaxies it is important to understand the selection effects behind the quasar samples and in particular if the selection criteria exclude foreground galaxies with certain properties (most importantly a high dust content). Here we present spectroscopic follow-up from the 10.4-m GTC telescope of a dust-reddened quasar, eHAQ0111+0641, from the extended High A_V Quasar (HAQ) survey. We find that the z=3.21 quasar has a foreground Damped Lyman-alpha Absorber (DLA) at z=2.027 along the line of sight. The DLA has very strong metal lines due to a moderately high metallicity (with an inferred lower limit of 25% of the solar metallicity), but a very large gas column density along the line-of-sight in its host galaxy. This discovery is further evidence that there is a dust bias affecting the census of metals, caused by the combined effect of dust obscuration and reddening, in existing samples of z>2 DLAs. The case of eHAQ0111+0641 illustrates that dust bias is not only caused by dust obscuration, but also dust reddening.

7 pages, 4 figures. Accepted for publication in A&A. A few typos have been corrected

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Cited by in corpus (6)

• Dust depletion of metals from local to distant galaxies I: Peculiar nucleosynthesis effects and grain growth in the ISM
• The effect of dust bias on the census of neutral gas and metals in the high-redshift Universe due to SDSS-II quasar colour selection
• Solving the conundrum of intervening strong MgII absorbers towards GRBs and quasars
• On the dust properties of high redshift molecular clouds and the connection to the 2175 Å extinction bump
• Gaia-assisted selection of a quasar reddened by dust in an extremely-strong Damped Lyman-α Absorber at z=2.226
• The galaxy counterpart and environment of the dusty Damped Lyman-alpha Absorber at z=2.226 towards Q1218+0832