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Session 122 - Galaxies, Clusters of Galaxies & IGM.
Oral session, Saturday, January 10
In principle, lines of sight toward quasars can be used as probes of galaxy evolution over the entire redshift interval, 0 < z < 5, that quasars are observed. High resolution Mg \sc ii absorption profiles contain diagnostic information of the structures and processes in galaxies over the epoch of observation.
We consider the variety of complex structure apparent in a sample of 26 HIRES/Keck Mg \sc ii absorbers at 0.4 < z < 1.0. Particularly, we address the question of what fraction of this absorption is produced in halos and what fraction arises from galaxy disks. Ensembles of synthetic spectra are generated from model galaxies with rotating thick disk and with radial infall kinematics. We apply a battery of statistical tests to compare these model profiles to the data, and find that pure disk and pure halo models can be ruled out. However, various models with rotating disk and infall/halo contributions produce ensembles of profiles that are consistent with the data. One important discrepancy is the existence in the data of a kinematic component that is intermediate between a halo and a thick disk. This component could indicate material that is being ejected from the disk, or that is in the process of joining the rotation of the disk in an infall model. We conclude that the variety of Mg \sc ii profiles can be explained by the gas in disks and halos of galaxies not very much different than galaxies in the local Universe.
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