A Measurement of the Three‐dimensional Clustering of CivAbsorption‐Line Systems on Scales of 5–1000h⁻¹Mpc

Abstract

We examine the three-dimensional clustering of C IV absorption-line systems using an extensive catalog of QSO heavy-element absorbers drawn from the literature. We measure clustering by a volumeweighted integral of the correlation function called the reduced second-moment measure, and include information from both along and across QSO lines of sight, thus enabling a full determination of the three-dimensional clustering of absorbers, as well as a comparison of alongÈ and acrossÈline-of-sight clustering properties. Here we present the three-dimensional reduced second-moment estimator for a three-dimensional point process probed by one-dimensional lines of sight, and apply our algorithm to a sample of 345 C IV absorbers with median redshift SzT \ 2.2, drawn from the spectra of 276 QSOs. We conÐrm the existence of signiÐcant clustering on comoving scales of up to 100 h~1 Mpc and (q 0 \ 0.5), Ðnd that the additional acrossÈline-of-sight information strengthens the evidence for clustering on scales from 100 to 150 h~1 Mpc. There is no evidence of absorber clustering along or across lines of sight for scales from 150 to 1000 h~1 Mpc. We show that with a 300 times larger catalog, such as that to be compiled by the Sloan Digital Sky Survey (100,000 QSOs), use of the full three-dimensional estimator and acrossÈline-of-sight information will substantially increase clustering sensitivity. We Ðnd that standard errors are reduced by a factor of 2È20 on scales of 30È200 h~1 Mpc, in addition to the factor of (300)1@2 reduction from the larger sample size, e †ectively increasing the sample size by an extra factor of 4È400 at large distances. Subject headings : cosmology : observations È intergalactic medium È large-scale structure of universe È methods : statistical È quasars : absorption lines

An excess of damped Lyman galaxies near quasi-stellar objects

“…Söchting, Clowes & Campusano 2004, and references therein) whilst QSOs themselves seem to cluster over similar distances (Croom et al 2004; Porciani, Magliocchetti & Norberg 2004). Even larger scale structures have been reported ranging from tens (Steidel et al 1998; Söchting, Clowes & Campusano 2002; Haines et al 2003) to hundreds (Quashnock, Vanden Berk & York 1996; Loh, Quashnock & Stein 2001; Haines, Campusano & Clowes 2004) of comoving Mpc. Large‐scale structures of many Mpc are therefore pervasive from the lowest (e.g.…”

Metal absorption systems in spectra of pairs of QSOs: how absorbers cluster around QSOs and other absorbers

“…Tytler, Sandoval & Fan (1993) saw no sign of periodicity on 10–210 Mpc scales in the 3D distribution of 268 Mg ii absorption systems. Loh, Quashnock & Stein (2001) examined the 3D distribution of 345 C iv systems from 276 QSOs and found evidence for clustering on scales up to 220 Mpc ( q 0 = 0.5). Vanden Berk et al (2000) found four metal‐line absorption systems towards QSOs near to the HDF, two of which have redshifts that place them in the second most populated peak in the galaxy redshift distribution.…”

Size estimates for intervening C IV absorbers from high-resolution spectroscopy of APM 0827+5255

“…Line parameters are consistent with a photoionized gas (Rauch et al 1996). The C iv absorbers appear to be highly clustered (Sargent, Boksenberg & Steidel 1988; Petitjean & Bergeron 1994; Loh, Quashnock & Stein 2001) and have been thought to originate in gas clouds orbiting in galactic haloes (Sargent et al 1979; Steidel 1993; Petitjean & Bergeron 1994; Mo & Miralda‐Escudé 1996). Hydrodynamical simulations also support a picture in which high‐redshift C iv arises in protogalactic clumps (PGCs), i.e.…”