The Nature of QSO Absorption Lines: Abundances, Physical Conditions, and Environment

Details The Nature of QSO Absorption Lines: Abundances, Physical Conditions, and Environment The Nature of QSO Absorption Lines: Abundances, Physical Conditions, and Environment

Jun 1997

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1997phdt........12t&link_type=abstract

Thesis (PHD). THE UNIVERSITY OF WISCONSIN - MADISON , Source DAI-B 57/12, p. 7571, Jun 1997, 528 pages.

Computer Science

1

Metallicity, Galaxies, Lyman Alpha

Scientific paper

This dissertation presents spectroscopic studies of HS1946+7658, HS1700+6416, and H1821+643, three radio-quiet QSOs at redshifts of 3.05, 2.72, and 0.297 respectively. High resolution (20 km s-1) high signal-to-noise spectroscopy of HS1946+7658 and HS1700+6416 yields the following results. (1) Several of the C IV absorbers are narrow implying that T < 50000 K, and therefore these absorbers are probably photoionized. (2) The abundance patterns of two damped Lyman α absorbers are similar to those of low metallicity Milky Way stars suggesting early stages of chemical enrichment. (3) Photoionization modeling of the HS1946+7658 associated absorber near the QSO redshift indicates that the metallicity is high, comparable to solar, but the models also indicate that the absorbing gas is at least a few hundred kpc away from the QSO. Modeling of the HS1700+6416 associated absorber indicates that the metallicity must be at least 1/5 solar, but the single zone photoionization model may be too simplistic. (4) Two C IV doublets in a dense C IV cluster show the weak line of one C IV doublet apparently aligned with the strong line of a different C IV doublet, i.e., line locked, but this may be coincidental. (5) The metallicities of the HS1700+6416 Lyman limit absorbers are constrained. Finally, we have studied the relationship between low redshift $/rm Lyα clouds and galaxies in the direction of H1821+643. We find: (1) The O VI doublet is unambiguously detected at z = 0.2250 along with H I Lyα and Lyβ . Two emission line galaxies are close to the sight line at this redshift, so the O VI could arise in the intracluster medium of a group of galaxies or the large gaseous halo of the closer galaxy. (2) The number of Lyα clouds per unit redshift is significantly greater than the number observed in lower sensitivity surveys. (3) Some Lyα clouds are associated with single galaxies or groups of galaxies, and some are apparently located in voids. However, there are no strong Lyα clouds in the vicinity of the two most prominent galaxy clusters.

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