On the selection of damped Lyman α systems using Mg II absorption at 2 < zabs < 4
Author
dc.contributor.author
Berg, T. A. M.
Author
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Ellison, S. L.
Author
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Prochaska, J. X.
Author
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Sánchez Ramírez, R.
Author
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López Morales, Sebastián
Author
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D'Odorico, V.
Author
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Becker, G.
Author
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Christensen, L.
Author
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Cupani, G.
Author
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Denney, K.
Author
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Worseck, G.
Admission date
dc.date.accessioned
2018-04-09T18:34:56Z
Available date
dc.date.available
2018-04-09T18:34:56Z
Publication date
dc.date.issued
2017-01
Cita de ítem
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MNRAS 464, L56–L60 (2017)
es_ES
Identifier
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10.1093/mnrasl/slw185
Identifier
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https://repositorio.uchile.cl/handle/2250/147222
Abstract
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The XQ-100 survey provides optical and near-infrared coverage of 36 blindly selected, intervening damped Lyman alpha systems (DLAs) at 2 < z(abs) < 4, simultaneously covering the MgII doublet at lambda lambda 2796, 2803 angstrom, and the Ly alpha transition. Using the XQ-100 DLA sample, we investigate the completeness of selecting DLA absorbers based on their MgII rest-frame equivalent width (W-0(2796) 0) at these redshifts. Of the 29 DLAs with clean MgII profiles, we find that six (20 per cent of DLAs) have W-0(2796) 0 < 0.6 angstrom. The DLA incidence rate of W-0(2796) 0 < 0.6 angstrom absorbers is a factor of similar to 5 higher than what is seen in z similar to 1 samples, indicating a potential evolution in the MgII properties of DLAs with redshift. All of the W-0(2796) 0 < 0.6 angstrom DLAs have low metallicities (-2.5 < [M/H] < -1.7), small velocity widths (v(90) < 50 km s(-1)), and tend to have relatively low N(H I). We demonstrate that the exclusion of these low W-0(2796) 0 DLAs results in a higher mean N(H I) which in turn leads to an similar to 7 per cent increase in the cosmological gas density of HI of DLAs at 2 < z(abs) < 4; and that this exclusion has a minimal effect on the H I-weighted mean metallicity.