The Evolution of Galaxy Fueling and Feedback in the Last 7 Billion Years

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Most of the atomic matter in the Universe courses through the dark, vast spaces between galaxies. This diffuse gas cycles into and out of galaxies multiple times. It will form new stars and become swept up in violent stellar end-of-life processes. Astronomers believe that this gaseous cycle lies at the heart of galaxy evolution. Yet, it has been difficult to observe directly. This project will include analysis of new telescope observations of hundreds of galaxies and their associated gaseous halos. Combining these data with large computer simulations will greatly advance the current picture of galaxy evolution. In addition, the analysis will track how the composition of the gas evolves over billions of years of cosmic history. This program includes an educational component focused on training University of Washington students in scientific research. Driven by recent advancements in UV instrumentation and computational capabilities, observations and simulations of the diffuse gas in the circumgalactic medium (CGM) are a new frontier of galaxy evolution studies. This study will directly address key questions about the physical connection between galaxies and their CGM. The observational dataset combines high-resolution HST/COS UV spectra of 30 z=1 QSOs with deep, optical spectroscopy and imaging from Gemini and Keck telescopes of hundreds of foreground galaxies per QSO field. The comprehensive galaxy-absorber catalogs produced by this study will: (1) be 5 times larger than all previous low-redshift samples combined; (2) cover an epoch that has never before been systematically surveyed (z = 0.3 -1; spanning approx. 5 Gyr), and (3) expand the physical distances probed in the halos from 0.5 -3 times the virial radii. In total, this program will constrain the physical properties of gas physically associated with a large, varied sample of galaxies at redshifts ranging from 0.1-1 and compare these quantities with cosmological, hydrodynamical simulations. This program will serve as a benchmark for the next decade of CGM studies. In collaboration with faculty and staff at Seattle Central College (SCC), this program will also establish a multifaceted undergraduate research program designed to facilitate STEM student transfers between local community colleges and the University of Washington and retain, mentor, and financially support transfer students. This research and mentorship program will foster education in STEM and broaden participation in science.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.