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The Absorption Lines in Quasi-Stellar Objects

Cohen, Judith G. (1973) The Absorption Lines in Quasi-Stellar Objects. Astrophysical Journal, 181 . pp. 619-625. ISSN 0004-637X. doi:10.1086/152076.

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The gas producing the absorption lines seen in the spectra of some high-redshift QSOs can be physically related to the QSO or it can be located by chance on the line of sight to the quasar. If it is physically adjacent to the quasar, it will be photoionized and the observed pattern of absorption lines can be produced. However, an ejection model has great difficulty explaining the sharpness of the observed absorption features compared with the large difference between absorption and emission redshift. A model in which the gas is part of the intergalactic medium or the extreme outer parts of galaxies is discussed. In this case, the gas may be collisionally ionized. To produce the observed ions C iv, N v, and O vi in absorption, the temperature must be about 10^5 °K. For solar metal abundance, it is then surprising that La is the strongest line in absorption. An attempt to enhance the La absorption by adding a cool region in which hydrogen is predominantly neutral fails as this region is photoionized by radiation from the hot region. Therefore, the metal abundance in the absorbing gas must be less than solar if the gas is not photoionized.

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Cohen, Judith G.0000-0002-8039-4673
Additional Information:© American Astronomical Society • Provided by the NASA Astrophysics Data System. Received 1972 August 9; revised 1972 December 6. We are very grateful to Professor J. Silk for many illuminating conversations. We are grateful to the Miller Institute for Basic Research for financial support.
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Miller Institute for Basic Research in ScienceUNSPECIFIED
Subject Keywords:abundances — intergalactic medium — quasi-stellar sources or objects
Record Number:CaltechAUTHORS:20190529-103834357
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:95878
Deposited By: George Porter
Deposited On:29 May 2019 20:15
Last Modified:16 Nov 2021 17:16

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