AAS 201st Meeting, January, 2003
Session 79. Intergalactic Material: Its Structure and Composition
Poster, Wednesday, January 8, 2003, 9:20am-6:30pm, Exhibit Hall AB

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[79.10] A Detailed Investigation of the Intergalactic Medium Toward PG1116+215

K. R. Sembach (STScI), T. M. Tripp (Princeton), B. D. Savage (U. Wisconsin)

We present Far Ultraviolet Spectroscopic Explorer (FUSE) and Space Telescope Imaging Spectrograph (STIS) observations of the intergalactic absorption systems toward the QSO PG1116+215 (l=223\fdg36, b=62\fdg21,z=0.177). These datasets have spectral resolutions R \equiv \lambda/\Delta\lambda \approx 15,000 and 45,000, respectively. We detect at least 14 Ly\alpha absorbers with rest frame equivalent widths W\lambda > 50 mÅ, as well as numerous metal-line features in the z=0.1386 and z=0.166 systems. \ion{O}{6} \lambda1031.926 absorption is clearly detected in both of these metal-line systems. We present a detailed analysis of the kinematical structure and ionization properties of the two \ion{O}{6} absorbers, and discuss the results in conjunction with the results available from investigations of other \ion{O}{6} systems. Both \ion{O}{6} absorbers occur at redshifts similar to those of groups of galaxies in the general direction of PG1116+215. We compare these new high-resolution spectra to previous low-resolution observations, and we describe the relationship of the absorbers with galaxies at similar redshifts. Our results add to the growing base of available information that suggests that the intergalactic \ion{O}{6} absorption traces a substantial reservoir of baryonic material in the low-redshift universe.

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