The Intergalactic and Circumgalactic Medium Surrounding Star-Forming Galaxies at Redshifts 2<z<3

• Main Author: Rudie, Gwen Charlena
• Format: Others
• Language: en
• Published: 2013
• Online Access: https://thesis.library.caltech.edu/7728/1/thesis-final.pdf; Rudie, Gwen Charlena (2013) The Intergalactic and Circumgalactic Medium Surrounding Star-Forming Galaxies at Redshifts 2<z<3. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/Z9PZ56T6. https://resolver.caltech.edu/CaltechTHESIS:05202013-155707736 <https://resolver.caltech.edu/CaltechTHESIS:05202013-155707736>

<p>We present measurements of the spatial distribution, kinematics, and physical properties of gas in the circumgalactic medium (CGM) of 2.0&lt;z&lt;2.8 UV color-selected galaxies as well as within the 2&lt;z&lt;3 intergalactic medium (IGM). These measurements are derived from Voigt profile decomposition of the full Ly&#945; and Ly&#946; forest in 15 high-resolution, high signal-to-noise ratio QSO spectra resulting in a catalog of &#8764;6000 HI absorbers. </p> <p>Chapter 2 of this thesis focuses on HI surrounding high-z star-forming galaxies drawn from the Keck Baryonic Structure Survey (KBSS). The KBSS is a unique spectroscopic survey of the distant universe designed to explore the details of the connection between galaxies and intergalactic baryons within the same survey volumes. The KBSS combines high-quality background QSO spectroscopy with large densely-sampled galaxy redshift surveys to probe the CGM at scales of &#8764;50 kpc to a few Mpc. Based on these data, Chapter 2 presents the first quantitative measurements of the distribution, column density, kinematics, and absorber line widths of neutral hydrogen surrounding high-z star-forming galaxies. </p> <p>Chapter 3 focuses on the thermal properties of the diffuse IGM. This analysis relies on measurements of the &#8764;6000 absorber line widths to constrain the thermal and turbulent velocities of absorbing &quot;clouds.&quot; A positive correlation between the column density of HI and the minimum line width is recovered and implies a temperature-density relation within the low-density IGM for which higher-density regions are hotter, as is predicted by simple theoretical arguments. </p> <p>Chapter 4 presents new measurements of the opacity of the IGM and CGM to hydrogen-ionizing photons. The chapter begins with a revised measurement of the HI column density distribution based on this new absorption line catalog that, due to the inclusion of high-order Lyman lines, provides the first statistically robust measurement of the frequency of absorbers with HI column densities 14 ≲ log(N_HI/cm^-2) ≲ 17.2. Also presented are the first measurements of the column density distribution of HI within the CGM (50 &lt;d &lt; 300 pkpc) of high-z galaxies. These distributions are used to calculate the total opacity of the IGM and IGM+CGM and to revise previous measurements of the mean free path of hydrogen-ionizing photons within the IGM. This chapter also considers the effect of the surrounding CGM on the transmission of ionizing photons out of the sites of active star-formation and into the IGM. </p> <p>This thesis concludes with a brief discussion of work in progress focused on understanding the distribution of metals within the CGM of KBSS galaxies. Appendix B discusses my contributions to the MOSFIRE instrumentation project. </p>