On the selection of damped Lyman α systems using Mg II absorption at 2 < zabs < 4
The XQ-100 survey provides optical and near-infrared coverage of 36 blindly selected, intervening damped Lyman α systems (DLAs) at 2 < z < 4, simultaneously covering the MgII doublet at λλ2796, 2803Å, and the Ly α transition. Using the XQ-100 DLA sample, we investigate the completeness of sele...
| Autores: | , , , , , , , , , , |
|---|---|
| Tipo de recurso: | artículo |
| Estado: | Versión publicada |
| Fecha de publicación: | 2017 |
| País: | España |
| Institución: | Consejo Superior de Investigaciones Científicas (CSIC) |
| Repositorio: | DIGITAL.CSIC. Repositorio Institucional del CSIC |
| OAI Identifier: | oai:digital.csic.es:10261/376295 |
| Acceso en línea: | http://hdl.handle.net/10261/376295 |
| Access Level: | acceso abierto |
| Palabra clave: | Galaxies: abundances Galaxies: high-redshift Galaxies: ISM Quasars: absorption lines |
| Sumario: | The XQ-100 survey provides optical and near-infrared coverage of 36 blindly selected, intervening damped Lyman α systems (DLAs) at 2 < z < 4, simultaneously covering the MgII 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 MgII restframe equivalent width (W ) at these redshifts. Of the 29 DLAs with clean MgII profiles, we find that six (20 per cent of DLAs) have W < 0.6 Å. The DLA incidence rate of W < 0.6Å absorbers is a factor of ~5 higher than what is seen in z ~ 1 samples, indicating a potential evolution in the MgII properties of DLAs with redshift. All of the W < 0.6Å DLAs have low metallicities (-2.5 < [M/H] < -1.7), small velocity widths (v < 50 km s), and tend to have relatively low N(H I). We demonstrate that the exclusion of these low W 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 HI of DLAs at 2 < z < 4; and that this exclusion has a minimal effect on the HI-weighted mean metallicity. © 2016 The Authors |
|---|