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Paper: Properties of Absorbers in Quasars at High Redshift: Towards an Understanding of the Near-Quasar Host Environment
Volume: 373, The Central Engine of Active Galactic Nuclei
Page: 299
Authors: Simon, L.E.; Hamann, F.W.; Pettini, M.
Abstract: We employ absorption-line analysis, a unique technique to determine quasar abundances as well as the properties of the physical environment around the quasars such as densities, distances and ionizations, for several high-redshift quasars. We find that 80% of the associated systems we observe show partial coverage. Densities determined from the presence of low-ionization ions and absence of excited-state absorption are very low, from < 1 to 30 cm−3. These low densities suggest very large distances from the quasar source, from 60 to 825 kpc, too far to be easily understood as instrinsic to the source, contradicting the partial coverage evidence. We contend that this may be due to shielding gas near the source, allowing the absorbing gas to remain close the source with low densities. We discuss implications of these findings for the star formation histories of the near-quasar environment.
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