Far Ultraviolet Spectroscopy of the Intergalactic and Interstellar Absorption Toward 3 C 273

We present Far Ultraviolet Spectroscopic Explorer observations of the molecular, neutral atomic, weakly ionized, and highly ionized components of the interstellar and intergalactic material toward the quasar 3C 273. We identify Lyβ absorption in 8 of the known intergalactic Lyα absorbers along the sight line with rest-frame equivalent widths Wr(Lyα) & 50 mÅ. Refined estimates of the H I column densities and Doppler parameters (b) of the clouds are presented. We find a range of b ≈ 16− 46 km s−1. We detect multiple H I lines (Lyβ – Lyθ) in the 1590 km s−1 Virgo absorber and estimate logN(H I) = 15.85±0.10 0.08, ten times more H I than all of the other absorbers along the sight line combined. The Doppler width of this absorber, b ≈ 16 km s−1, implies T . 15, 000 K. We detect O VI absorption at 1015 km s−1 at the 2− 3σ level that may be associated with hot, X-ray emitting gas in the Virgo Cluster. We detect weak C III and O VI absorption in the IGM at z = 0.12007; this absorber is predominantly ionized and has N(H+)/N(H I) ≥ 4000Z−1, where Z is the metallicity. Strong Galactic interstellar O VI is present between −100 and +100 km s−1, with an additional high-velocity wing containing about 13% of the total O VI between ∼ +100 and ∼ +240 km s−1. The Galactic O VI, N V, and C IV lines have similar shapes, with roughly constant ratios across the –100 to +100 km s−1 velocity range. The high velocity O VI wing is not detected in other species. Much of the interstellar high ion absorption probably occurs within a highly fragmented medium within the Loop IV remnant or in the outer cavity walls of the remnant. Multiple hot gas production mechanisms are required. The broad O VI absorption wing likely traces the expulsion of hot gas out of the Galactic disk into the halo. A flux limit of 5.4×10−16 erg cm−2 s−1 on the amount of diffuse O VI emission present ∼ 3.5 off the 3C 273 sight line combined with the observed Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, MD 21218 Department of Astronomy, University of Wisconsin, Madison, WI 53706 CASA and JILA, Department of Astrophysical and Planetary Sciences, University of Colorado, Boulder, CO 80309 Laboratory for Astronomy and Solar Physics, Code 681, Goddard Space Flight Center, Greenbelt, MD 20771