Abstract
We use a radiation hydrodynamic simulation of the hydrogen reionization
epoch to study O I absorbers at z ˜ 6. The intergalactic medium
(IGM) is reionized before it is enriched; hence, O I absorption
originates within dark matter haloes. The predicted abundance of O I
absorbers is in reasonable agreement with observations. At z = 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
108.4 M⊙, 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. O I
absorbers have neutral hydrogen columns of
1019-1021 cm-2, suggesting a close
resemblance between objects selected in O I and H I 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
H I column density is enriched enough to violate the upper limits on the
O I 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 language | English |
---|---|
Pages (from-to) | 1818-1835 |
Journal | Monthly Notices of the Royal Astronomical Society |
Volume | 436 |
Issue number | 2 |
DOIs | |
Publication status | Published - 1 Oct 2013 |
Keywords
- galaxies: evolution
- galaxies: formation
- galaxies: haloes
- galaxies: high-redshift
- quasars: absorption lines
- cosmology: theory