Strong Clustering of High-Redshift Lyα Forest Absorption Systems

We use new observations of very weak CIV absorption lines associated withhigh-redshift Lyman-alpha absorption systems to measure the high-redshiftLyman-alpha line two-point correlation function (TPCF). These very weak CIVabsorption lines trace small-scale velocity structure that cannot be resolvedby Lyman-alpha absorption lines. We find that (1) high-redshift Lyman-alphaabsorption systems with N(HI) > 3.10^14 cm^{-2} are strongly clustered inredshift, (2) previous measurements of the Lyman-alpha line TPCF underestimatedthe actual clustering of the absorbers due to unresolved blending ofoverlapping velocity components, (3) the present observations are consistentwith the hypothesis that clustering of Lyman-alpha absorption systems extendsto lower column densities, but maybe with smaller amplitude in the correlationfunction, and (4) the observed clustering is broadly compatible with thatexpected for galaxies at z \sim 2-3. We interpret these results as suggestingthat many or most Lyman-alpha absorbers may arise in galaxies even at highredshifts, and, therefore, that the Lyman-alpha forest probes processes ofgalaxy formation and evolution for redshifts \lesssim 5.Comment: 12 pages, includes 4 figures, uses AASTEX style file aaspp4.tex. Accepted for publication in ApJLetter