THE GALAXY ENVIRONMENT OF O VI ABSORPTION SYSTEMS

摘要

We combine a FUSE sample of O VI absorbers (z < 0.15) with a database of 1.07 million galaxy redshifts to explore the relationship between absorbers and galaxy environments. All 37 absorbers with N_(O VI) ≥ 10~(13.2) cm~(-2) lie within 800 h_(70)~(-1) kpc of the nearest galaxy, with no compelling evidence for O VI absorbers in voids. The O VI absorbers often appear to be associated with environments of individual galaxies. Gas with 10% ± 5% solar metallicity (O VI and C III) has a median spread in distance of 350-500 h_(70)~(-1) kpc around L~* galaxies and 200-270 h_(70)~(-1) kpc around 0. 1L~* galaxies (ranges reflect uncertain metallicities of gas undetected in Lyα absorption). In order to match the O VI line frequency, (dN/dz) ≈ 20 for N_(O VI) ≥ 10~(13.2) cm~(-2), galaxies with L ≤ 0.1L~* must contribute to the cross section. Lyα absorbers with N_(H I) ≥ 10_(13.2) cm~(-2) cover ～50% of the surface area of typical galaxy filaments. Two-thirds of these show O VI and/or C III absorption, corresponding to a 33%-50% covering factor at 0.1 Z_☉ and suggesting that metals are spread to a maximum distance of 800 h_(70)~(-1) kpc, within typical galaxy supercluster filaments. Approximately 50% of the O VI absorbers have associated Lyα line pairs with separations (△υ)_(Lyα) = 50-200 km s~(-1). These pairs could represent shocks at the speeds necessary to create copious O VI, located within 100 h_(70)~(-1) kpc of the nearest galaxy and accounting for much of the two-point correlation function of low-z Lyα forest absorbers.