I propose to study the properties of the highly ionized gas in the intergalactic medium using ground-based spectroscopy of high-redshift quasars. Observations of absorption lines of the highly ionized species O VI, N V, and C IV provide a way to measure th e properties of this highly ionized gas, which is thought to harbour a significant fraction of all baryons. Using data from the UVES spectrograph on the Very Large Telescope Chile (a European facility), I aim to look for evolution in the properties of O VI absorption systems with redshift. Specifically, I will: (a) determine whether highly ionized intergalactic absorbers contain multiple gaseous phases; (b) seek an understanding of the differences between highly ionized gas at low redshift and high redshift ; c) test the predictions of cosmological simulations; and (d) investigate the origin of hot gas in Damped Lyman alpha systems (DLAs), that may represent the high-redshift precursors of galaxies like the Milky Way. This project will make use of new spectr al analysis techniques pioneered at the Institut d'Astrophysique de Paris (the host institution), which correlate the absorption in spectra separated by small angular scales on the sky. This technique will enable the spatial distribution of highly ionized gas in the high-redshift Universe to be studied for the first time.
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