Neutron star quasi-normal modes as a probe of the theory of gravity
An interesting prospect in the era of gravitational-wave astronomy is to probe general relativity (GR) with strong-field asteroseismology – the observation of vibration modes of compact objects such as black holes and neutron stars. In this seminar I'll discuss how the coupling to the new degrees of freedom present in modified theories of gravity can alter the general-relativistic spectrum. These changes include not only a shift in the GR frequencies, but also entirely new families of modes with no counterpart in GR. I will discuss a realization of this idea in the context of scalar-tensor theories of gravity, a well-motivated alternative to GR with various applications in cosmology. Finally, I comment on astrophysical scenarios where these new modes could leave imprints on electromagnetic and gravitational wave observations.