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The interstellar medium at high redshift: the sub-DLA at z=2.06 towards the quasar J2123−0050Milutinovic, Nikola 01 September 2009 (has links)
DLAs are the primary reservoirs of neutral gas available for star formation at high redshift. However, DLAs are metal poor and lack molecular gas. In this thesis, I present a study of an extraordinary case of a z=2.06 sub-DLA towards the quasar J2123−0050, which is characterized by a metallicity that approaches solar, and a high H2 molecular fraction (log f(H2) = −2.54). Furthermore, this SDLA harbors HD molecules, only the third such detection at high redshift, and with the highest (HD/2H2) fraction of -2.75. To understand these observations, I study the effects of dust depletion and photoionization on the interpretation of raw abundance measurements. I find that the magnitude of photoionization and dust depletion effects has a profound impact on the interpretation of this SDLA. The calculated corrections lower the elemental and molecular abundances suggesting that the ISM in the SDLA towards J2123−0050 exhibits properties similar to the
gas in the local sightlines.
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