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Paper: Intrinsic Narrow Absorption Lines in the HST/STIS Echelle Archive
Volume: 311, AGN Physics with the Sloan Digital Sky Survey
Page: 243
Authors: Ganguly, R.; Sembach, K.R.; Charlton, J.C.; Eracleous, M.; Palma, C.; Tripp, T.M.
Abstract: We are in the process of searching for intrinsic low velocity-dispersion absorbers in high spectral resolution observations of quasars with HST/STIS. Our goal is to produce a catalog of truly intrinsic absorbers, selected without explicit velocity bias, using the signature of partial coverage (i.e., dilution of absorption troughs) as a selection criterion. Thus far, we have searched though the spectra of 22 quasars and have detected 75 metal-line systems. Of the 75 systems, 15 lie within 5000 km/s of the quasar redshift ("associated" systems). So far, we have found 8 systems that exhibit the signature of partial coverage, of which 5 are associated systems. (Not all non-associated systems have been tested yet.) We conclude that samples using velocity-selection for intrinsic absorbers are: (1) contaminated by absorbers possibly not close to the central engine, and (2) incomplete to a fair fraction of absorbers which are likely to originate close to the central engine. In addition, we point out a few interesting cases of associated O VI absorption from our survey, including a possibly new class of HI + O VI-only absorber.
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