HST/COS Spectra of Three QSOs that Probe the Extended Gaseous Halo of a Single Galaxy

Type Conference Paper
Names Brian A. Keeney, J. T. Stocke, J. L. Rosenberg, C. W. Danforth, J. M. Shull, B. D. Savage, J. C. Green
Proceedings Title Bulletin of the American Astronomical Society
Conference Name American Astronomical Society, AAS Meeting #217, #345.12
Volume 43
Date January 1, 2011
URL http://adsabs.harvard.edu/abs/2011AAS...21734512K
Library Catalog NASA ADS
Abstract We present moderate-resolution Cosmic Origins Spectrograph (COS) far-UV spectra of three QSOs that probe the extended gaseous halo of the nearby spiral galaxy ESO 157-G049 (cz = 1673 km/s; L = 0.1 L*) at impact parameters of 53, 66, and 124 kpc. H I Lyman-alpha absorption is detected at the galaxy redshift in the spectra of all three QSOs and metal lines of Si III, Si IV, and C IV are detected in two of the three spectra. No metals are detected in the sight line that probes ESO 157-G049 along its minor axis at an impact parameter of 124 kpc, implying that there is no galactic wind that reaches these radii. Further, no low ions (i.e., C II, Si II) associated with ESO 157-G049 are detected in any of the QSO spectra so its gaseous halo is highly ionized even at radii of 50 kpc. These spectra allow us to probe the three-dimensional structure of low- and intermediate-ionization gas in nearby galaxy halos for the first time and begin to map the distribution of metals and energy as a function of impact parameter and position angle with respect to the galaxy.
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