A Search for Intergalactic Ne VIII in the COS Spectrum of PKS0405-123

Type Conference Paper
Names Anand Narayanan, B. Savage, B. Wakker, Y. Yao, C. Danforth, C. Froning, J. Green, B. Keeney, K. Sembach, M. Shull
Proceedings Title Bulletin of the American Astronomical Society
Conference Name American Astronomical Society, AAS Meeting #215, #460.05
Volume 42
Pages 490
Date January 1, 2010
URL http://adsabs.harvard.edu/abs/2010AAS...21546005N
Library Catalog NASA ADS
Abstract The high S/N COS spectrum of the UV bright quasar PKS0405-123 provides the sensitivity required for a search of Ne VIII in QSO metal line absorption systems at z > 0.47. The EUV lines of Ne VIII 770,780 A are ideal tracers of hot collisionally ionized gas at T (0.5 - 1) x 106 K. However, detecting these weak lines require spectra of good S/N in which the effects of detector fixed pattern noise are well understood. The z = 0.49510 O VI multiphase metal line absorption system along this sight line is ideally suited for a search for Ne VIII. Chen & Mulchaey (2009) have identified an emission line galaxy of extended morphology at a projected physical separation of 77 kpc from this absorber. The COS spectrum provides coverage of O II 834, O III 833, O IV 788, C III 977 and higher order Lyman series lines associated with this absorber at a much higher S/N than the FUSE and STIS observations for this target. The improved line measurement based on the COS spectrum, combined with the information on O VI from STIS is used to derive detailed physical conditions in the multiple gas phases of this absorber. Evidence for the presence of shock-heated gas would imply that the absorber is tracing either transition temperature gas in the galaxy's halo or an intergalactic WHIM filament connecting galaxies as part of the large scale structure. This research has been supported by the NASA Cosmic Origins Spectrograph Program through a sub-contract to the University of Wisconsin from the University of Colorado.
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