The Chemical Enrichment of Gas in BALQSOs: Rapid Star Formation in the Early History of Galaxies

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Session 42 -- Metallicity in AGN and the Near-AGN Environment
Oral presentation, 8:30am - 12:30pm, June 14, 1995, 9:20am - 6:30pm

[42.10] The Chemical Enrichment of Gas in BALQSOs: Rapid Star Formation in the Early History of Galaxies

\def\Zsun{\ifmmode {\rm Z}_{\odot} \else Z$_{\odot}$\fi} \def\hi{H\,{\sc i}} \def\civ{\ifmmode {\rm C} \,{\sc iv} \else C\,{\sc iv} \fi} \def\ciii{\ifmmode {\rm C} \,{\sc iii} \else C\,{\sc iii} \fi} \def\niii{N\,{\sc iii}} \def\nv{N\,{\sc v}} \def\oiii{O\,{\sc iii}} \def\ovi{O\,{\sc vi}} Kirk Korista (Univ.\ of Ky), Fred Hamann (UCSD), Jason Ferguson (Univ.\ of Ky), Gary Ferland (Univ.\ of Ky)

Utilizing spectra from ground-based and Hubble Space Telescope observations, Korista et al.\ (1992) identified an unprecedented number of broad absorption lines in the BALQSO 0226$-$1024 (z$_{em} = 2.256$). Here we use many of their measured column densities to investigate the BAL gas chemical abundances. Despite the rather loose constraints on the ionizing continuum shape and fractions of the observed \hi\/ and \civ\/ column densities present in the \nv\/ -- \ovi\/ gas, photoionization calculations for the highly ionized gas in this BALQSO indicate that the metallicity of the BAL gas in 0226$-$1024 is at least solar, independent of continuum shape, but less than about 10~\Zsun\/. Although the results are more difficult to interpret, consideration of the lower ionized gas containing \ciii\/, \niii\/, and \oiii\/, yields predictions of metallicity Z~$\approx$~6--10~\Zsun\/. Because the BALs in 0226$-$1024 that are measurable from the ground have columns typical in BALQSOs, the main result, Z~$>$~\Zsun\/ should be generic to the BALQSO phenomenon. The enrichment scenario favored here is one that is expected in the cores of massive galaxies: early rapid star formation producing metal enriched gas. Metallicities enhanced over solar will increase the opacity of the outflowing BAL gas without significantly increasing the mass load of whatever is driving the outflow. This should have a significant impact on radiative acceleration models of BAL outflows which have, up to now, assumed solar abundances.

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