High-Redshift Superclustering of Quasi-stellar Object Absorption-Line Systems on 100 [ITAL]h[/ITAL][TSUP]−1[/TSUP] Mpc Scales

We have analyzed the clustering of C IV absorption line systems in anextensive new catalog of heavy element QSO absorbers. The catalog permitsexploration of clustering over a large range in both scale (from about 1 toover 300 Mpc) and redshift (z from 1.2 to 4.5). We find significant evidence(5.0 sigma) that C IV absorbers are clustered on comoving scales of 100 Mpc andless --- similar to the size of voids and walls found in galaxy redshiftsurveys of the local universe --- with a mean correlation function $\xi = 0.42\pm 0.10$ over these scales. We find, on these scales, that the meancorrelation function at low (z=1.7), medium (z=2.4), and high redshift (z=3.0)is $\xi=0.40 \pm 0.17$, $0.32 \pm 0.14$, and $0.72 \pm 0.25$, respectively.Thus, the superclustering is present even at high redshift; furthermore, itdoes not appear that the superclustering scale, in comoving coordinates, haschanged significantly since then. We find 7 QSOs with rich groups of absorbers(potential superclusters) that account for a significant portion of theclustering signal, with 2 at redshift $z\sim 2.8$. We find that thesuperclustering is just as evident if we take $q_0=0.1$ instead of 0.5;however, the inferred scale of clustering is then 240 Mpc , which is largerthan the largest scales of clustering known at present. This discrepancy may beindicative of a larger value of $q_0$, and hence $\Omega_0$. The evolution ofthe correlation function on 50 Mpc scales is consistent with that expected incosmologies with density parameter ranging from $\Omega_0 = $ 0.1 to 1.Finally, we find no evidence for clustering on scales greater than 100 Mpc($q_0=0.5$) or 240 Mpc ($q_0=0.1$).Comment: 16 LaTeX pages with 3 encapsulated Postscript figures included, uses AASTeX (v. 4.0) available at ftp://ftp.aas.org/pubs/ , to appear in The Astrophysical Journal Letter