Galaxies and Intergalactic Matter at Redshift Z ∼ 3: Overview

We present the first results from a survey of the relative spatial distributions of galaxies, intergalactic neutral hydrogen, and intergalactic metals at high redshift. We obtained high-resolution spectra of 8 bright QSOs at 3.1 < z < 4.1 and spectroscopic redshifts for 431 Lyman-break galaxies (LBGs) at slightly lower redshifts. Comparing the locations of galaxies to the absorption lines in the QSO spectra shows that the intergalactic medium contains less neutral hydrogen than the global average within r < ∼ 0.5h comoving Mpc of LBGs and more than average at slightly larger distances 1 < ∼ r < ∼ 5h comoving Mpc. The intergalactic medium within the largest overdensities at z ∼ 3, which will presumably evolve into the intracluster medium by z ∼ 0, is rich in neutral hydrogen and CIV. The lack of HI absorption at small distances from LBGs appears unlikely to be produced solely by the Lyman continuum radiation they emit; it may show that the galaxies’ supernovae-driven winds maintain their measured outflow velocities of ∼ 600km s for a few hundred million years and drive away nearby intergalactic gas. We present correlation functions of galaxies with Lyman-α forest flux decrements, with CIV systems, and with other galaxies. We describe the association of galaxies with damped Lyman-α systems and with intergalactic HeII opacity. A strong observed correlation of galaxies with intergalactic metals supports the idea that Lyman-break galaxies’ winds have enriched their surroundings. Subject headings: galaxies: formation, galaxies: high-redshift, intergalactic medium, quasars: absorption lines