The interstellar medium at high redshift: the sub-DLA at z=2.06 towards the quasar J2123−0050

• Main Author: Milutinovic, Nikola
• Other Authors: Ellison, Sara L.
• Language: English; en
• Published: 2009
• Subjects: DLAs; ISM; qasars; observations; ionization; abundances; UVic Subject Index::Sciences and Engineering::Physics::Astrophysics
• Online Access: http://hdl.handle.net/1828/1711

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.