Abstract

The last decades have firmly established the existence of a dark sector of our universe. Yet, details of its particle content have evaded all laboratory probes. In this talk I will describe how the cosmic-dawn era, which saw the formation of the first galaxies, holds a wealth of information about dark matter and the astrophysics of the early universe. The next decade will see detailed maps of this era with both 21-cm and space telescopes. I will show how to use the upcoming data to measure structure formation at smaller scales—and earlier times—than ever before. Moreover, I will introduce a new standard ruler to measure the expansion rate of our cosmos during unexplored eras. These studies pave the way to understanding dark matter and its role in the first structure formation, and provide us with a unique window to test the energy content of our universe.