Neutral-Gas-Phase Metal Abundances in ZnII-Selected Quasar Absorption Line Systems near Redshift $z=1.2$

Abstract

We present ten metallicity measurements for quasar absorbers near $z=1.2$ that were selected for having unusually significant ZnII absorption in their SDSS spectra. Follow-up UV space spectroscopy of the Ly$\alpha$ region shows that all ten have damped Ly$\alpha$ (DLA) absorption, corresponding to neutral hydrogen column densities in the range $2.4\times 10^{20}$ $\le$ N(HI) $\le$ $2.5\times 10^{21}$ atoms cm${}^{-2}$, and indicating that the gas is very optically thick and essentially neutral. The sample is a very small subset of systems compiled by searching the University of Pittsburgh catalog of $\approx 30,000$ intervening MgII absorption line systems in SDSS quasar spectra up to DR7. We started by isolating $\approx 3,000$ that had strong MgII absorption in the redshift interval $1.0<z<1.5$ in brighter background quasars. Of these, 36 exhibited significant absorption near ZnII. Space UV spectroscopy was then obtained for nine of these (25% of the total), and a tenth system in a fainter quasar was found in the HST archives. The result is a representative sample of the highest Zn${}^{+}$ columns of gas within the DLA population. These ZnII-selected systems define the upper envelope of DLA metallicities near $z=1.2$. They show a tight anti-correlation between N(HI) and [Zn/H], with the higher metallicity systems clearly exhibiting more depletion based on [Cr/Zn] values. The various metal-line measurements (Zn, Cr, Si, Fe, Mn) indicate evolved neutral gas with $-0.9\le$ [Zn/H] $\le +0.4$.

arXiv commentAccepted for publication in MNRAS

References in corpus (16)

• The chemical composition of the Sun
• Damped Lyman Alpha Systems at z<1.65: The Expanded SDSS HST Sample
• The large-scale structure of the halo of the Andromeda Galaxy Part I: global stellar density, morphology and metallicity properties
• Discovery of Damped Lyman-Alpha Systems at Redshifts Less Than 1.65 and Results on their Incidence and Cosmological Mass Density
• The most metal-poor damped Lyman-alpha systems: Insights into chemical evolution in the very metal-poor regime
• Ionization Properties and Elemental Abundances in Damped Ly alpha Systems
• A Homogeneous Sample of Sub-DLAs I: Construction of the Sample and Chemical Abundance Measurements
• Consensus report on 25 years of searches for damped Ly$\alpha$ galaxies in emission: Confirming their metallicity-luminosity relation at $z\gtrsim 2$
• A 2dF spectroscopic study of globular clusters in NGC 5128: Probing the formation history of the nearest giant Elliptical
• The ESO UVES Advanced Data Products Quasar Sample - VI. Sub-Damped Lyman-$\alpha$ Metallicity Measurements and the Circum-Galactic Medium
• Manganese Abundances in Cluster and Field Stars
• The Statistical Properties of Neutral Gas at z<1.65 from UV Measurements of Damped Lyman Alpha Systems
• Interstellar Gas-phase Element Depletions in the Small Magellanic Cloud: A Guide to Correcting for Dust in QSO Absorption Line Systems
• The difference in metallicity distribution functions of halo stars and globular clusters as a function of galaxy type: A tracer of globular cluster formation and evolution
• A scaling law for interstellar depletions
• The early phases of Milky Way's chemical evolution

Cited by in corpus (1)

• The distribution and properties of DLAs at z $\le$ 2 in the EAGLE simulations