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Sub-damped Lyman alpha systems in the XQ-100 survey - I. Identification and contribution to the cosmological H I budget

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  • Additional Information
    • Publisher Information:
      Oxford University Press 2019-09
    • Abstract:
      Sub-damped Lyman alpha systems (subDLAs; H I column densities of 19.0 <= logN(HI) < 20,3) are rarely included in the cosmic HI census performed at redshifts z(abs) greater than or similar to 1.5, yet arc expected to contribute significantly to the overall H I mass budget of the Universe. In this paper, we present a blindly selected sample of 155 subDLAs found along 100 quasar sightlines (with a redshift path-length Delta X = 475) in the XQ-100 legacy survey to investigate the contribution of subDLAs to the H I mass density of the Universe, The impact of X-Shooter's spectral resolution on Ly alpha absorber identification is evaluated, and found to be sufficient for reliably finding absorbers down to a column density of logN(HI) >= 18.9. We compared the implications of searching for subDLAs solely using H 1 absorption versus the use of metal lines to confirm the identification, and found that metal-selection techniques would have missed 75 subDLAs. Using a bootstrap Monte Carlo simulation, we computed the column density distribution function (f(N, X)) and the cosmological Hi mass density (Omega(HI)) of subDLAs and compared with our previous work based on the XQ-100 damped Lyman 0, systems. We do not find any significant redshift evolution in f(N, X) or Omega(HI) for subDLAs. However, subDLAs contribute 10-20 per cent of the total Omega(HI) measured at redshifts 2 < z < 5, and thus have a small but significant contribution to the HI budget of the Universe.© 2019 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society
    • Subject Terms:
      Galaxies: high-redshift; Galaxies: ISM; Quasars: absorption lines; artículo
    • Availability:
      Open access content. Open access content
      openAccess
    • Note:
      English
    • Other Numbers:
      CTK oai:digital.csic.es:10261/191943
      Monthly Notices of the Royal Astronomical Society 488(3): 4356-4369 (2019)
      0035-8711
      10.1093/mnras/stz2012
      1257728408
    • Contributing Source:
      CSIC
      From OAIster®, provided by the OCLC Cooperative.
    • Accession Number:
      edsoai.on1257728408
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