We study the cluster of H I and O VI absorption systems and the claimed detection of O vin absorption from the intergalactic medium at z ≈ 0.0567, associated with a group of galaxies toward the BL Lac object PKS 2155-304. As measured by spectrographs on the Hubble Space Telescope, Far Ultraviolet Spectroscopic Explorer, and Chandra, this system appears to contain gas at a variety of temperatures. We analyze this multiphase gas in a clumpy-infall model. From the absence of C IV and Si in absorption in the Lyα clouds, we infer metallicities less than 2.5%-10% of solar values. The only metals are detected in two O VI absorption components, offset by ±400 km s -1 from the group barycenter (cz ≈ 16,600 km s-1)- The O VI components may signify "nearside" and "backside" infall into the group potential well, which coincides with the claimed O VIII absorption. If the claimed O VIII detection is real, our analysis suggests that clusters of strong Lyα and O VI absorbers, associated with groups of galaxies, may be the "signposts" of shock-heated metal-enriched baryons. Through combined UV and X-ray spectra of H I and O VI, O VII, and O VIII, one may be able to clarify the heating mechanism of this multiphase gas.
| Identifer | oai:union.ndltd.org:ETSU/oai:dc.etsu.edu:etsu-works-15179 |
| Date | 10 September 2003 |
| Creators | Michael Shull, J., Tumlinson, Jason, Giroux, Mark L. |
| Publisher | Digital Commons @ East Tennessee State University |
| Source Sets | East Tennessee State University |
| Detected Language | English |
| Type | text |
| Source | ETSU Faculty Works |
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