Abundances in broad-line regions of QSOs

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Session 24 -- AGNs/QSOs - High Luminosity
Display presentation, Tuesday, June 13, 1995, 9:20am - 6:30pm

[24.06] Abundances in broad-line regions of QSOs

James Merleau (University of Victoria, Dept. of Astronomy, Box 3055, MS 770, Victoria, BC, V8W 3P6)

Information on the chemical composition and history of the gas in Quasars can be obtained from the ratios of broad emission lines. Hamann and Ferland(1993, ApJ), working with data from the literature, found a trend for higher metallicities at higher redshifts. This seems to imply IMFs favouring high-mass stars in the high redshift quasars, and also high star formation rates and short timescales for infall. Similar conditions are thought to be present during the formation of giant ellipticals. The purpose of the present study is to verify the Hamann and Ferland results and also to try to automate the line measuring process. The abundances of broad-line regions in a sample of 304 QSOs from the Large Bright Quasar Survey are studied. The relative abundances are estimated via NV/CIV and NV/HeII. The line intensities are measured in an automated fashion from the digital spectra, integrating the flux above the continuum in fixed(rest) wavelength windows. The results are compared with line intensities obtained by gaussian fitting. The same process is followed with IUE data to verify the redshift-metallicity relation.

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