The host haloes of OI absorbers in the reionization epoch

Kristian Finlator, Joseph A. Muñoz, B. D. Oppenheimer, S. Peng Oh, Feryal Özel, Romeel Davé

Research output: Contribution to journalArticlepeer-review

35 Scopus citations


We use a radiation hydrodynamic simulation of the hydrogen reionization epoch to study OI absorbers at z ~ 6. The intergalactic medium (IGM) is reionized before it is enriched; hence, OI absorption originates within dark matter haloes. The predicted abundance of OI absorbers is in reasonable agreement with observations. Atz = 10, ≈70 per cent of sightlines through atomically cooled haloes encounter a visible (NOI > 1014cm-2) column. Reionization ionizes and removes gas from haloes less massive than 108.4M, but 20 per cent of sightlines through more massive haloes encounter visible columns even at z = 5. The mass scale of absorber host haloes is 10-100 times smaller than the haloes of Lyman-break galaxies and Lyman α emitters, hence absorption probes the dominant ionizing sources more directly. OI absorbers have neutral hydrogen columns of 1019-1021 cm-2, suggesting a close resemblance between objects selected in OI and HI absorption. Finally, the absorption in the foreground of the z = 7.085 quasar ULAS J1120+0641 cannot originate in a dark matter halo because halo gas at the observed HI column density is enriched enough to violate the upper limits on the OI column. By contrast, gas at less than one-third the cosmic mean density satisfies the constraints. Hence, the foreground absorption likely originates in the IGM.

Original languageEnglish (US)
Pages (from-to)1818-1835
Number of pages18
JournalMonthly Notices of the Royal Astronomical Society
Issue number2
StatePublished - Dec 2013


  • Cosmology: theory.
  • Galaxies: evolution
  • Galaxies: formation
  • Galaxies: haloes
  • Galaxies: highredshift
  • Quasars: absorption lines

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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