Despite of the weak couplings to normal matter, light axion fields can be significantly sourced by neutron stars, leaving potentially detectable signals in gravitational waves from binary neutron star inspirals. In this talk, I am going to talk about how the axions affect the inspiral waveform, and to report a recent search for such axions with GW170817. If time allows, I will also talk about a separate topic on making ansatz for black holes in generic gravitational theories.
Our group coordinated the "Numerical Relativity and High Energy Physics" IRSES network (2012-2015). Here is a list of the global network meetings organized: