2006MNRAS.365..615S

We study the clustering properties of metals in the intergalactic medium (IGM) as traced by 619 Civ and 81 SIIV absorption components with N≥ 10¹²/cm2 and 316 MgII and 82 FeII absorption components with N≥ 10^11.5/cm2 in 19 high signal-to-noise ratio (60-100/pixel), high-resolution (R= 45000) quasar spectra. Civ and SIIV trace each other closely and their line-of-sight correlation functions ξ(v) exhibit a steep decline at large separations and a flatter profile below ~150 km/s, with a large overall bias. These features do not depend on absorber column densities, although there are hints that the overall amplitude of ξ_Civ(v) increases with time over the redshift range detected (1.5-3). Carrying out a detailed smoothed particle hydrodynamic simulation (2x320³, 57 Mpc³ comoving), we show that the Civ correlation function cannot be reproduced by models in which the IGM metallicity is constant or a local function of overdensity (Z∝Δ^2/3). However, the properties of ξ_Civ(v) are generally consistent with a model in which metals are confined within bubbles with a typical radius R_sabout sources of mass ≥M_s. We derive best-fitting values of R_s~ 2 comoving Mpc and M_s~ 10¹²M_☉at z= 3. Our lower-redshift (0.5-2) measurements of the MgII and FeII correlation functions also uncover a steep decline at large separations and a flatter profile at small separations, but the clustering is even higher than in the z= 1.5-3 measurements, and the turnover is shifted to somewhat smaller distances, ~75 km/s. Again, these features do not change with column density, but there are hints that the amplitudes of ξ_MgII(v) and ξ_FeII(v) increase with time. We describe an analytic `bubble' model for these species, which come from regions that are too compact to be accurately simulated numerically, deriving best-fitting values of R_s~ 2.4 Mpc and M_s~ 10¹²M_☉. Equally good analytic fits to all four species are found in a similarly biased high-redshift enrichment model in which metals are placed within 2.4 comoving Mpc of M_s~ 3x10⁹ sources at z= 7.5.