The Properties of Intergalactic CivAbsorption. II. Which Systems Are Associated with Galaxy Outflows?

Using the extremely high S/N quasar absorption-line sample described in thefirst paper of the series, we investigate which intergalactic CIV absorptionline systems could be directly associated with galactic outflows at z = 2 - 3.5from an analysis of the velocity widths of the CIV absorption line systems.Only about half the systems with a peak tau(CIV) above 0.4 in the 1548 Angstromline (roughly a column density of CIV above about 2 x 10^13 cm^-2) havevelocity widths large enough to originate in this way, and very few of theweaker systems do. The median velocity full width at a tenth max is found to be50 km/s for systems with peak tau(CIV) in the range 0.1--0.4 and 160 km/s forsystems with a peak tau(CIV) in the range 0.4--3. We show that this criticalvalue of tau(CIV) also separates systems that could be ionized by galaxy-likespectra from those in which the ionization is clearly AGN-dominated. Togetherthe results are consistent with a picture in which almost all the lower columndensity, and at least half the higher column density, systems lie in the moregeneral IGM whereas about half of the higher column density systems could beproduced directly by the outflows and possibly be ionized by their parentgalaxies.Comment: 25 pages, 12 figures. Accepted for publication in A