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http://hdl.handle.net/20.500.12386/29184
Titolo: | On the selection of damped Lyman α systems using Mg II absorption at 2 < z<SUB>abs</SUB> < 4 | Autori: | Berg, T. A. M. Ellison, S. L. Prochaska, J. X. Sánchez-Ramírez, R. Lopez, S. D'ODORICO, Valentina Becker, G. Christensen, L. CUPANI, Guido Denney, K. Worseck, G. |
Data pubblicazione: | 2017 | Rivista: | MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY | Numero: | 464 | Fascicolo: | 1 | Da pagina:: | L56 | Abstract: | The XQ-100 survey provides optical and near-infrared coverage of 36 blindly selected, intervening damped Lyman α systems (DLAs) at 2 < z<SUB>abs</SUB> < 4, simultaneously covering the Mg II doublet at λλ2796, 2803Å, and the Ly α transition. Using the XQ-100 DLA sample, we investigate the completeness of selecting DLA absorbers based on their Mg II rest-frame equivalent width (W<SUB>0</SUB>^{2796}) at these redshifts. Of the 29 DLAs with clean Mg II profiles, we find that six (20 per cent of DLAs) have W<SUB>0</SUB>^{2796} < 0.6 Å. The DLA incidence rate of W<SUB>0</SUB>^{2796} < 0.6 Å absorbers is a factor of ∼5 higher than what is seen in z ∼ 1 samples, indicating a potential evolution in the Mg II properties of DLAs with redshift. All of the W<SUB>0</SUB>^{2796} < 0.6 Å DLAs have low metallicities (-2.5 < [M/H] < -1.7), small velocity widths (v<SUB>90</SUB> < 50 km s<SUP>-1</SUP>), and tend to have relatively low N(H I). We demonstrate that the exclusion of these low W<SUB>0</SUB>^{2796} DLAs results in a higher mean N(H I) which in turn leads to an ∼7 per cent increase in the cosmological gas density of H I of DLAs at 2 < z<SUB>abs</SUB> < 4; and that this exclusion has a minimal effect on the H I-weighted mean metallicity. | URI: | http://hdl.handle.net/20.500.12386/29184 | URL: | https://academic.oup.com/mnrasl/article/464/1/L56/2891003 | ISSN: | 0035-8711 | DOI: | 10.1093/mnrasl/slw185 | Bibcode ADS: | 2017MNRAS.464L..56B | Fulltext: | open |
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