Strong Clustering of High-Redshift Lyα Forest Absorption Systems

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Abstract
We use new observations of very weak C IV absorption lines associated with high-redshift Lyα absorption systems to measure the high-redshift Lyα line two-point correlation function (TPCF). These very weak C IV absorption lines trace small-scale velocity structure that cannot be resolved by Lyα absorption lines. We find that (1) high-redshift Lyα absorption systems with N(H I) > 3 × 1014 cm-2 are strongly clustered in redshift, (2) previous measurements of the Lyα line TPCF underestimated the actual clustering of the absorbers due to unresolved blending of overlapping velocity components, (3) the present observations are consistent with the hypothesis that clustering of Lyα absorption systems extends to lower column densities, but maybe with smaller amplitude in the correlation function, and (4) the observed clustering is broadly compatible with that expected for galaxies at z ~ 2-3. We interpret these results as suggesting that many or most Lyα absorbers may arise in galaxies even at high redshifts, and, therefore, that the Lyα forest probes processes of galaxy formation and evolution for redshifts z 5.
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