Location: ERC 526
Scientific Advisor: Hsiao-Wen Chen
Publications: ADS | arXiv
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Ph.D. Thesis Defense
Defense date: July 23, 2019
Multi-Pronged Studies of Diffuse Halo Gas around Massive Quiescent Galaxies"
Ph.D. Committee members: Hsiao-Wen Chen, Wendy Freedman, Nick Gnedin, Rich Kron.
"Fakhri's ground breaking research addresses long-standing puzzles concerning the formation and growth of massive galaxies. During his graduate study, Fakhri led multiple innovative and ambitious observing programs to characterize the diffuse gas content in and around distant galaxies. His thesis work casts critical new insights into the chemical enrichment in quiescent halo. Fakhri is on a great trajectory and will continue his outstanding research at Carnegie Observatories as a Carnegie fellow in the fall.
- Hsiao-Wen Chen, Ph.D. advisor
Thesis Abstract: While significant progress has been made in understanding various aspects of galaxy evolution in the last few decades, a self-consistent explanation for the diffuse gaseous halos (also known as the circumgalactic medium; CGM) surrounding galaxies still eludes us. Particularly puzzling is the high incidence of cool gas in the gaseous halos of massive quiescent galaxies, which is at odds with their lack of star-formation activity and the theoretical expectation that their diffuse baryons are predominantly hot. Characterizing the physical properties of the gaseous halos of massive quiescent galaxies is necessary to build an empirical understanding of the co-evolution of galaxies and gas over cosmic time. In my thesis talk, I will present a series of observational studies that investigate the gaseous halos of intermediate-redshift (z~0.5) massive elliptical galaxies, using precision analysis of quasar absorption-line spectroscopy. I will demonstrate what the elemental abundances and abundance patterns, kinematics, and ionization states of the gas tell us about the complex baryonic processes taking place on large (~100 kpc) and small (<10 kpc) scales in the halos of these "red and dead" galaxies. The results of my work shed light on the origin and fate of the cool gas around massive ellipticals, as well as feedback mechanisms responsible for preventing star-formation in massive halos.
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