Ben Safdi (U. Michigan) “The Search for Axion Dark Matter

Abstract:

Dark matter is the dominant source of matter in our Universe.  However, while dark matter dictates the evolution of large-scale astrophysical systems through its gravitational effects, the particle nature of dark matter is unknown.  In this talk I will review the current status of the search for the particle dark matter candidate called the axion, which is both well-motivated theoretically and also relatively unexplored experimentally.  I will focus specifically on new large-scale numerical simulations of axion cosmology that lead to precise predictions for (i) the axion mass that gives the correct dark matter abundance, and (ii) the structure of dark matter on small astrophysical scales.  I will show that axion dark matter may be harder to detect directly in the laboratory than previously thought, given that the cosmological axions are mostly confined to compact minihalos, but that this dark matter scenario may still be detectable using radio telescope searches for axion-induced radio lines.