Dark Matter on the Smallest Scales

University Of North Carolina At Chapel Hill, Chapel Hill NC

Investigators

Abstract

This award funds the research activities of Professor Adrienne Erickcek at the University of North Carolina at Chapel Hill. The protons, neutrons, and electrons that compose all the elements on the periodic table account for less than sixteen percent of the matter in the Universe. The composition of the remaining eighty-four percent of matter is one of the major outstanding questions in physics. As part of this award, Professor Erickcek will investigate how the smallest dark-matter structures can be used to understand the composition and origins of dark matter. This project serves the national interest by promoting the progress of science through both the knowledge it will generate and the training it will provide undergraduate and graduate students. This project will have broader impacts as well. Professor Erickcek will continue to expose high-school physics students to the mystery of dark matter using the "How Do You Weigh a Galaxy?" curriculum that she designed in partnership with the Morehead Planetarium and Science Center. She will also share the quest to understand dark matter more widely by giving public lectures. More technically, the size of the smallest dark-matter structures depends on the origins of dark matter, and their abundance provides information about the expansion history of the Universe during its first tenth of a second. If dark matter was produced through pair production, then dark-matter annihilations within the dense centers of the smallest dark-matter clumps may finally provide a non-gravitational signature of the existence of dark matter. Under this award, Professor Erickcek will extend the scope and improve the accuracy of the method her team has developed to calculate the dark-matter annihilation rate within the smallest halos, leading to more robust constraints on thermal dark-matter production. She will also explore how observations of kiloparsec-scale density fluctuations constrain the non-thermal creation of dark matter. Finally, this award will support Professor Erickcek's investigation of the connection between the matter power spectrum and the velocity dispersion of the dark-matter particles, which aims to improve our ability to use observations of small-scale structure to learn about the fundamental properties of the dark-matter particle. 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.