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The complete Lyman-alpha absorption seen in the spectra of z > 6
quasars suggest that cosmological reionization may have completed as
late as z = 6.2. However, this late reionization scenario remains
controversial due in part to studies of high-redshift galaxy
luminosity functions, which favor a highly-ionized IGM out to z > 6.5.
Low-ionization metal absorption systems provide an alternative means
to probe a wide range of IGM neutral fractions. To this end, we have
conducted a search for O I in the first high-resolution spectra of
quasars at 5 < z < 6.4. The high-resolution data do reveal an
overabundance of O I at z > 6 towards SDSS J1148+5251. However, the
nature of these remains something of a mystery. I will present these
new systems and discuss their implications for the IGM at z ~ 6.
These absorbers may represent the last pockets of neutral gas to be
reionized at z ~ 6. Alternatively, they may be caused by enriched gas
in galaxy halos.
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