Speaker
Prof.
Edward Hardy
(University of Oxford)
Description
Axions are a well-motivated candidate for new physics. If the associated Peccei-Quinn symmetry was ever restored after inflation, cosmic strings form and inevitably produce a contribution to the stochastic gravitational wave background. I will discuss the resulting gravitational wave spectrum combining effective field theory with numerical simulations. Additionally, the axions produced by strings form (at least a component of) dark matter. I will argue that such axion dark matter has interesting substructure, in particular forming solitonic “axion stars”, which lead to possible observational and experimental signals.
