Dark-Matter Interactions at Cosmic Dawn

Our view of the origin and evolution of the Universe has been progressing steadily in recent decades, but some of the deepest mysteries endure. One of these is the nature of the dark matter than permeates the Universe and is crucial for the formation of large-scale structure in the Universe.

This proposal seeks to develop the theoretical and analysis tools to capitalize upon the extraordinary potential of forthcoming measurements that will probe the distribution and physical conditions of matter in the Universe at the time that the first stars form. These "21-cm" measurements take advantage of the spectral line associated with the transition of neutral hydrogen atoms between states in which the electron spin is flipped. Although theorists have made considerable strides in modeling the expected signals, there are still several crucial physical effects that have yet to be incorporated. There is also the need to model the effects of various models of dark matter on the signal, so that these signatures can be searched for in the observational data. With ongoing experiments such as HERA, whose data we plan to analyze as part of the proposed research, there are prospects to measure the global strength of the 21-cm signal as well as its spatial fluctuations. Even in the absence of a detection, upper limits set by HERA can be used to rule out a large set of motivated dark matter models. The tools developed by the proposed research will allow results from these new measurements to be understood and interpreted properly, thus enabling an abundance of discovery space to be opened.