The age and chemical evolution of high-redshift QSOs

Details The age and chemical evolution of high-redshift QSOs The age and chemical evolution of high-redshift QSOs

Jun 1992

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1992apj...391l..53h&link_type=abstract

Astrophysical Journal, Part 2 - Letters (ISSN 0004-637X), vol. 391, no. 2, June 1, 1992, p. L53-L57.

Astronomy and Astrophysics

Astrophysics

124

Chemical Evolution, Galactic Evolution, Interstellar Chemistry, Quasars, Abundance, Astronomical Models, Astronomical Spectroscopy, Carbon, Nitrogen, Red Shift

Scientific paper

Observed N V/C IV line ratios in QSOs are used to estimate the N/C abundances, infer the metallicities, and constrain the chemical history of the broad-line gas. Spectral synthesis calculations suggest that nitrogen is overabundant by factors of about 2-9 in the high-redshift (z greater than about 2) sources. Chemical enrichment models indicate that highly evolved gas, with metallicities reaching about 3-14 times solar, is needed to produce the N overabundance. Initial mass functions favoring high-mass stars are also required. The chemical evolution must occur in less than about 0.5 Gyr for the z is about 4 objects (if q(0) is about 1/2), implying that QSOs are associated with vigorous star formation. These results are consistent with the starburst model of AGNs.

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