On Models for the Ionization Structure of BAL Region Gas

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Session 105 -- Broad Absorption Line Quasars
Display presentation, Saturday, January 1, 9:30-6:45, Salons I/II Room (Crystal Gateway)

[105.05] On Models for the Ionization Structure of BAL Region Gas

M. Kopko, Jr., D.A. Turnshek, B.R. Espey (University of Pittsburgh)

A number of results on the column densities of Broad Absorption Line (BAL) region gas in QSOs have been derived under the assumptions that the clouds completely cover the background continuum source and no unresolved velocity structure exists. With the aid of spectra extending into the UV, these results may include column densities for different ions of the same element. Analysis of these results with Ferland's photoionization code CLOUDY shows that they are inconsistent with single-zone models for the ionization structure. Thus, some method for incorporating ionization structure into the gas appears to be necessary (e.g. Williams 1992, ApJ, 392, 99). We have incorporated density fluctuations into the photoionization calculations as a means of altering the ionization structure of BAL region clouds at a given line-of-sight velocity. Using this model we consider observational constraints on the density fluctuations.

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