COS Observations Of Intergalactic O VI Systems In The Spectrum Of PKS 0405-123

Type Conference Paper
Names Blair D. Savage, A. Narayanan, B. Wakker, C. Danforth, C. Froning, J. Green, B. Keeney, K. Sembach, M. Shull, J. Stocke, Y. Yao
Conference Name Bulletin of the American Astronomical Society
Volume 42
Pages 502
Date January 1, 2010
Library Catalog NASA ADS
Abstract Signal-to-noise > 35 observations with the COS of the QSO PKS 0405-123 (z em = 0.5726) at a resolution of 15 to 20 km/s from 1150 to 1780 A are analyzed to study the physical conditions in the prominent O VI absorption systems at z = 0. 16710, 0.18292, 0.36156, 0.36332 and 0.49501. These systems have previously been studied in STIS and FUSE spectra with S/N 10 to 15. The system at z = 0.16710 is a Lyman limit system with logN(HI) = 16.45 +/-0.05 (Prochaska et al. 2004). Chen and Mulchaey (2009) have found Galaxies with impact parameters of 81, 165 and 77 kpc associated with the z = 0.16710, O.36156, and 0.49501 absorbers. No galaxies with impact parameters < 1 Mpc have been found associated with the other two absorbers. The high S/N of the observations allows the measurement of important ions not previously detected and permits a careful evaluation of the kinematical relationships among the detected ions. The observations are being used to determine the origin of the ionization of O VI in simple and complex absorption systems. The high S/N allows a search for broad Ly alpha possibly associated with O VI if it is collisonally ionized at T 3x105 K. The multi-phase system at z = 0.16710 may be tracing a high velocity cloud in the halo of the associated galaxy. The UV properties of this absorber are similar to that for the high velocity clouds in the Milky Way halo where O VI is likely produced in interface regions between hot halo gas with T >1x106 K and the cooler gas of the HVC. The observations show that COS is extremely well suited for studies at low redshift of the surroundings of galaxies and their connection to the cosmic web.
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