期刊
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
卷 458, 期 4, 页码 4074-4121出版社
OXFORD UNIV PRESS
DOI: 10.1093/mnras/stw524
关键词
galaxies: abundances; galaxies: evolution; galaxies: formation; intergalactic medium; galaxies: ISM; quasars: absorption lines
资金
- ESO at the European Southern Observatory (ESO) Very Large Telescope (VLT) [91.A-0300]
- Agence Nationale de la Recherche (ANR) [ANR-08-BLAN-0316-01]
- Labex (Laboratoire d'Excellence) OCEVU ('Origines, Constituants et Evolution de l'Univers')
- OCEVU Labex [ANR-11-LABX-0060]
- A*MIDEX project - 'Investissements d'Avenir' French government program [ANR-11-IDEX-0001-02]
- CNRS
- CNES
- ESO science visitor program
- NSF [AST/1108830]
- NASA [NNX14AG74G]
- NASA/STScI grant [GO 12536]
- Division Of Astronomical Sciences
- Direct For Mathematical & Physical Scien [1108830] Funding Source: National Science Foundation
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 alpha absorbers (sub-DLAs, defined as absorbers with 19.0 < logN(HI) < 20.3) with redshift 0.584 <= 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 modelled Voigt profile features. The correlation between the velocity width Delta V-90 of the absorption profile and themetallicity 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.
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