| Names |
J. Michael Shull, C. Danforth, C. Froning, J. Green, B. Keeney, J. Stocke, Y. Yao, B. Savage, A. Narayanan, K. Sembach |
| Abstract |
We present an overview of far-UV Hubble Space Telescope observations (1150-1780 A, at 17 km/s resolution) taken by the Cosmic Origins Spectrograph (COS) of the QSO PKS 0405-123 at redshift zem = 0.5726 and FUV flux 3.5x10-14 erg/s/cm2/A. This spectrum illustrates the the power of COS for studying metal-enriched gas between the galaxies, distributed throughout the multiphase intergalactic medium (IGM). We used 7 orbits with 9 FP-split positions, obtained S/N = 35-45 over much of the G130M band (1150-1440 A), and detected numerous absorption features of hydrogen (Lya, Lyb) and heavy-element probes of metallicity. Ions that can be studied include lines (O VI, N V, Ne VIII) sensitive to hot gas produced by strong shocks produced in gravitational inflows to the Cosmic Web, in circumgalactic gas, and in galactic winds. The high S/N allows a search for broad Ly-alpha possibly associated with O VI in hot gas (105 to 106 K). This sight line also intercepts a high-velocity cloud seen in Si III at 110-170 km/s (LSR) and b = -37.55 in the Galactic halo. In the absorption system at z = 0.495, the Ne VIII doublet (770.41, 780.32 A) shifts into the COS band, allowing us to probe the warm-hot IGM at log T = 5.5-6.0, several times deeper than previous (STIS) studies (Prochaska et al. 2004; Howk et al. 2009). In other posters, members of the COS science team describe the detection of O VI absorbers at redshifts z = 0.16710, 0.18292, 0.36156, 0.36332, and 0.49501, including a Lyman Limit system at z = 0.16710 with log N(HI) = 16.45 +/- 0.05. The high S/N observations allow us to measure important ions previously not detected and to evaluate the kinematical relationships and physical conditions among the detected ions. |