Studies of the Cloud Structure, Ionization Structure, and Elemental Abundances in High Redshift QSO BAL Region Gas

Abstract

The nature of QSO broad absorption line (BAL) gas in terms of its cloud structure, ionization structure, and elemental abundances is discussed. HST-FOS spectroscopy of the individual components of a gravitationally lensed BAL QSO is used to place constraints on BAL cloud structure, with the finding that the average lineof-sight column densities are generally constant to within ±10% across a region which is likely to be approximately the size of the continuum source. Also, HST-FOS and ground-based spectroscopy of different ions of the same element in BAL QSOs reveal information that can be used to model ionization structure and elemental abundances. Analysis indicates that the absorbing clouds have non-uniform ionization and high elemental abundances. Outflows from QSOs with BAL regions may influence the chemical evolution of the universe at high redshift.