RUI: Implications of Non-Minimal Dark Sectors

One principal aim of these research activities is to better understand the origin and properties of the "dark matter" in our universe --- an as-yet mysterious form of matter that neither emits nor absorbs light, but nevertheless makes its presence felt via its gravitational pull on normal, visible matter. Over the next decade, a host of state-of-the-art laboratory experiments and telescopes will provide us with a wealth of new data. Professor Thomas will investigate novel ways in which we might be able to glean information about the dark matter --- and about other as-yet-undiscovered particles with which the dark matter might interact --- from this forthcoming data. The other principle aim of these research activities is to address fundamental questions concerning the history of our universe. To what extent could that history have differed from the canonical picture without the universe looking markedly different to us? If the history of the universe does in fact depart from the canonical picture, how could we tell? Answers to such questions would provide us with clues about the fundamental nature and properties of matter. Professor Thomas will investigate the scope of possible such departures and how they would impact the sizes and shapes of galaxies, the properties of ripples in the spacetime continuum known as gravitational waves (ripples which were discovered less than a decade ago and are now being used by astronomers as a tool to learn about black holes and other astrophysical phenomena), and other aspects of the observable universe which depend on its history. A significant portion of this award will be used to support undergraduate involvement in these research topics, thereby cultivating interest among the next generation of scientists and honing their computational skills. Stated in more technical terms, the research activities supported by this award have two principal goals. The first is to advance our collective understanding about the properties of the dark sector of our universe. This goal involves developing new methods of probing and constraining the structure of the dark sector, taking into account the full range of viable possibilities inherent within that sector. The results of these investigations will inform both theoretical efforts in dark-matter and dark-sector model-building and strategies for experimental dark-matter detection. The second goal of the project is to advance our understanding of how our universe evolved over time from the end of the reheating period following cosmic inflation to the present epoch. This goal involves developing methods for distinguishing between possible expansion histories for the universe on the basis of observational data --- data concerning, for example, the matter power spectrum or the properties of the cosmic microwave background. The results of these investigations will inform both theoretical and observational research efforts in early-universe cosmology. 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.